JP6322868B2 - Illumination system, license plate recognition system, illumination method and program - Google Patents

Description

  The present invention relates to an illumination system, a license plate recognition system, an illumination method, and a program using an illumination device that projects light toward a road surface on which a vehicle travels.

  2. Description of the Related Art In recent years, at a toll gate such as a highway, a vehicle monitoring system (a license plate recognition system) that captures a license plate of a traveling vehicle with an imaging device and acquires vehicle number information or the like described on the license plate has been operated. . In addition, in such a license plate recognition system, an illumination device such as an LED (Light Emitting Diode) illumination is separately arranged so that the imaging device can clearly pick up the license plate (for example, Patent Document 1). reference). Such an illuminating device is installed together with an imaging device so that a vehicle traveling on a road surface such as an expressway can be irradiated from the front side or the rear side in the traveling direction. Thereby, even at night, the imaging device can clearly image the license plate attached to the front or rear surface of the vehicle.

  In the above-described license plate recognition system, consideration is given so that as many vehicle license plates as possible can be imaged clearly by the imaging device. Specifically, the light distribution of the illuminating device is adjusted so as to have substantially uniform brightness (illuminance) in the imaging range of the imaging device. If it does so, the imaging device can image uniformly and clearly even if it is the license plate of the vehicle imaged in any area | region of the imaging range.

JP 2002-260165 A

However, the material and surface state of a license plate that is attached to a traveling vehicle and that is to be imaged may vary from vehicle to vehicle. For example, the license plate of a vehicle may differ in the material etc. which are used for every vehicle model, for example. If the material and surface condition of the license plate are different, the reflectance of light on the surface of the license plate will also be different. Therefore, even if an image is captured within an imaging range adjusted to have a uniform illuminance, depending on the vehicle, there may be a difference in the intensity of the reflected light that is collected on the imaging device, and clear imaging may not be possible. is there.
In addition, the mounting angle of the license plate may differ depending on the vehicle. For example, in the case of a motorcycle, the license plate may be attached slightly upward. Then, the specularly reflected light of the light projected from the illumination device may be collected in the imaging device, and the imaging may be out of focus.

  As described above, even if the light distribution of the illuminating device is adjusted so that the illuminance distribution in the imaging range is as uniform as possible, the material, surface state, and mounting angle of the license plate are different. There are vehicles that are not imaged.

  The present invention has been made in view of the above problems, and provides a lighting system, a license plate recognition system, a lighting method, and a program capable of acquiring clear imaging data for an imaging target with respect to more vehicles. Objective.

One aspect of the present invention is provided by a plurality of light source units that are provided so as to correspond to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on a road surface, each of which can independently adjust irradiation conditions. The illumination condition of the light source unit is set on the basis of state information indicating a state of a lighting device including a light emitting unit configured and the road surface acquired corresponding to the irradiation section or a vehicle traveling on the road surface. And an irradiation condition setting unit.

  According to another aspect of the present invention, the illumination system includes an imaging state determination unit that determines an imaging state of a license plate imaged by an imaging device that can capture a predetermined imaging range on the road surface. The irradiation condition setting unit sets the irradiation condition as the state information based on the imaging state determined by the imaging state determination unit.

  One embodiment of the present invention may further include a position specifying unit that specifies a position on the road surface of the license plate imaged by the imaging device in the illumination system, and the irradiation condition setting unit includes the position specifying unit. The irradiation condition of the light source unit corresponding to the irradiation section to which the position of the license plate specified by the unit belongs is set based on the imaging state.

  Further, according to one aspect of the present invention, in the above-described lighting system, the position specifying unit specifies a position at the time of the second and subsequent imaging of the license plate captured at the first time based on the traveling speed of the vehicle. It is characterized by that.

  Further, according to one aspect of the present invention, in the illumination system described above, the irradiation condition setting unit sets the irradiation condition based on a vehicle type determined by a vehicle type determination unit that can determine a vehicle type of a traveling vehicle. Features.

  Further, according to one aspect of the present invention, in the above-described lighting system, the irradiation condition setting unit is based on statistical information indicating a vehicle type composition ratio for each time zone of a vehicle traveling on the road surface as the state information. The irradiation conditions are set.

  According to another aspect of the present invention, there is provided a license plate recognition comprising: the above-described illumination system; and an imaging device capable of imaging a predetermined imaging range on the road surface and imaging a license plate of a vehicle traveling on the road surface. System.

In one embodiment of the present invention, a plurality of light sources are provided so as to irradiate corresponding to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on the road surface, each of which can independently adjust the irradiation conditions. An irradiation condition of a lighting device including a light emitting unit configured by a unit is set based on state information indicating a state of the road surface or a vehicle traveling on the road surface acquired in correspondence with the irradiation section. Lighting method to do.

In one embodiment of the present invention, a plurality of light sources are provided so as to irradiate corresponding to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on the road surface, each of which can independently adjust the irradiation conditions. The light source obtained in correspondence with the irradiation section based on state information indicating a state of the road surface or a vehicle traveling on the road surface is obtained by a computer of an illumination system having a lighting device including a light emitting unit configured by a unit. This is a program that functions as irradiation condition setting means for setting the irradiation conditions of the unit.

  According to the above-described illumination system, license plate recognition system, illumination method, and program, it is possible to acquire clear imaging data for an imaging target for more vehicles.

It is a figure showing the whole license plate recognition system composition concerning a 1st embodiment. It is a figure which shows the function structure of the license plate recognition system which concerns on 1st Embodiment. It is a figure which shows the structure of the illuminating device which concerns on 1st Embodiment. It is a figure which shows the function structure of the illuminating device which concerns on 1st Embodiment. It is a figure explaining the irradiation range of the illuminating device which concerns on 1st Embodiment. It is a 1st figure explaining the function of the imaging data analysis part which concerns on 1st Embodiment. It is a 2nd figure explaining the function of the imaging data analysis part which concerns on 1st Embodiment. It is a flowchart figure which shows the processing flow of the information collection apparatus which concerns on 1st Embodiment. It is a figure explaining the function of the imaging data analysis part which concerns on 2nd Embodiment. It is a figure explaining the function of the imaging data analysis part which concerns on the modification of 2nd Embodiment. It is a figure which shows the whole structure of the license plate recognition system which concerns on 3rd Embodiment. It is a figure which shows the function structure of the license plate recognition system which concerns on 3rd Embodiment. It is a flowchart figure which shows the processing flow of the information collection apparatus which concerns on 3rd Embodiment. It is a figure which shows the function structure of the license plate recognition system which concerns on 4th Embodiment. It is a figure explaining the statistical information storage part which concerns on 4th Embodiment. It is a flowchart figure which shows the processing flow of the information collection apparatus which concerns on 4th Embodiment. It is a 1st figure which shows the structure of the illuminating device which concerns on other embodiment. It is a 2nd figure which shows the structure of the illuminating device which concerns on other embodiment. It is a figure which shows the function structure of the illuminating device which concerns on other embodiment. It is a figure which shows the whole structure of the license plate recognition system which concerns on 5th Embodiment. It is a figure which shows the structure of the to-be-imaged reference member which concerns on 5th Embodiment. It is a figure explaining the arrangement | positioning method of the to-be-imaged reference member which concerns on 5th Embodiment. It is a figure which shows the function structure of the information collection apparatus which concerns on 5th Embodiment. It is a 1st figure explaining the process of the irradiation condition determination part which concerns on 5th Embodiment. It is a 2nd figure explaining the process of the irradiation condition determination part which concerns on 5th Embodiment. It is a figure which shows the processing flow of the information collection apparatus which concerns on 5th Embodiment.

  The license plate recognition system described below has a lighting device capable of adjusting irradiation conditions for each of a plurality of small areas (for example, three vertically and three horizontally) on a light emitting surface, and a road surface or a state of a vehicle traveling on the road surface The irradiation conditions for each of the small areas are appropriately controlled according to the state information indicating Hereinafter, each embodiment will be described in detail.

<First Embodiment>
Hereinafter, a license plate recognition system according to a first embodiment will be described with reference to the drawings.
The license plate recognition system according to the first embodiment includes an illumination device that can adjust the light emission intensity for each of the three small areas in the vertical and horizontal directions on the light emitting surface, and emits light for each small area according to the imaging state of the license plate. Control strength.

[Overall configuration of license plate recognition system]
FIG. 1 is a diagram showing an overall configuration of a license plate recognition system according to the first embodiment.
The license plate recognition system 100 includes an imaging device 1, a lighting device 2, a mounting column 3 that supports them, and an information collection device 4 installed in another area.

  The license plate recognition system 100 is a facility installed on a lane such as a general road or a toll road. The license plate recognition system 100 images, for example, the number plate on the rear surface side of the vehicle 101 from the rear side in the traveling direction of the vehicle 101 traveling on the road surface S of the lane 102, and obtains vehicle number information of the vehicle 101 from the captured data. get.

As shown in FIG. 1, the imaging device 1 is installed on the attachment column 3 so as to capture a predetermined imaging range on the road surface S, and is imaged from the rear side in the traveling direction of the vehicle 101 traveling on the lane 102. The rear surface including the license plate is imaged. Here, the “imaging range” is a range on the road surface S included in the imaging data generated by the imaging device 1. The imaging range of the imaging device 1 is set in a region on the back side of the mounting column 3 in the lane 102 (region after the vehicle 101 passes through the mounting column 3). Thereby, the imaging device 1 enables imaging of the license plate on the rear surface side of the vehicle 101 traveling in the imaging range. Further, the imaging device 1 generates imaging data continuously at a predetermined time interval (for example, every several tens of milliseconds).
Imaging data (imaging data P described later) obtained by imaging the license plate of the vehicle 101 is output to the information collecting device 4 installed in another area via wired or wireless communication.

As shown in FIG. 1, the illumination device 2 is installed on the mounting column 3 together with the imaging device 1 so that a predetermined irradiation range on the road surface S can be irradiated. Here, the “irradiation range” is a range in which the illumination device 2 can illuminate the road surface S brightly. The illumination range of the illumination device 2 is arranged so as to include the entire imaging range of the imaging device 1, and the light distribution is adjusted so that the imaging device 1 can acquire a clear image of the vehicle in the imaging range. Has been. Thereby, the imaging device 1 can generate clear imaging data of the license plate even if the vehicle is imaged at any location in the imaging range.
In addition, the specific structure of the illuminating device 2 which enables irradiation so that the imaging device 1 can acquire a clear image of the vehicle in the imaging range will be described later.

The mounting column 3 is a support column whose base end is fixedly installed on the road surface outside the lane 102 and extends upward inside the lane 102. The mounting column 3 is provided with the imaging device 1 and the illumination device 2 described above.
As an example, the mounting column 3 may be a cantilever cantilever as shown in FIG. 1 or a gantry installed so as to straddle the lane 102 in the width direction.

  The information collection device 4 performs a process of extracting vehicle number information and the like drawn on the imaged license plate with respect to the input image data. Further, the information collecting device 4 stores and accumulates the extracted vehicle number information together with information such as time information and an imaged area (an identifier of the imaging device 1). The vehicle number information collected in this way is useful for, for example, vehicle identification and traffic survey.

[Functional structure of license plate recognition system]
FIG. 2 is a diagram illustrating a functional configuration of the license plate recognition system according to the first embodiment.
As shown in FIG. 2, the license plate recognition system 100 according to the present embodiment includes an imaging device 1, a lighting device 2, and an information collection device 4. In addition, the information collection device 4 includes a communication unit 400, an imaging data analysis unit 401, an irradiation condition setting unit 402, and a storage unit 403.

  The communication unit 400 is a communication module that transmits and receives information to and from the imaging device 1 and the illumination device 2 via wireless or wired communication. For example, the information collection device 4 receives input of imaging data P generated by the imaging device 1 via the communication unit 400. Further, the information collection device 4 outputs the irradiation condition information D toward the illumination device 2 via the communication unit 400.

  The imaging data analysis unit 401 performs a predetermined analysis process on the imaging data P acquired by the imaging device 1. As illustrated in FIG. 2, the imaging data analysis unit 401 includes a position specifying unit 401a, an imaging state determination unit 401b, and a vehicle information extraction unit 401c.

The position specifying unit 401a performs a process of determining whether or not the license plate of the vehicle is captured in the captured image data P, and when determining that one or more license plates are captured, The position (position on the road surface S) is estimated.
The imaging state determination unit 401b acquires the imaging state of the license plate. Note that the imaging state determination unit 401b according to the present embodiment classifies the imaging state of the license plate as one of “good”, “dark”, and “bright” as described later.
When the imaging state of the license plate imaged in the imaging data P is “good” (that is, when the imaging is performed clearly), the vehicle information extraction unit 401c performs OCR (Optical Character) on the imaging data P. Recognition) processing and the like are performed to extract vehicle number information and the like. Further, the vehicle information extraction unit 401c stores and accumulates in the storage unit 403 while associating time information, area information, and the like with the extracted vehicle number information and the like. Thereby, the information collection device 4 can sequentially collect vehicle number information and the like regarding the passing vehicle.
Specific processing contents of the position specifying unit 401a and the imaging state determination unit 401b will be described in detail with reference to FIGS.

  The irradiation condition setting unit 402 changes the irradiation condition (described later) of the illumination device 2 according to the analysis result (number plate position and imaging state) of the imaging data P by the imaging data analysis unit 401. Specifically, the irradiation condition setting unit 402 creates information (irradiation condition information D) having the irradiation conditions of the illumination device 2 according to the analysis result by the imaging data analysis unit 401, and the irradiation condition information D is The data is output to the lighting device 2 via the communication unit 400. As will be described later, when the illumination apparatus 2 receives the irradiation condition information D created by the irradiation condition setting unit 402, the illumination apparatus 2 immediately changes the irradiation condition based on the irradiation condition information D.

  Note that the imaging data analysis unit 401 and the irradiation condition setting unit 402 described above may be realized by a CPU (Central Processing Unit) included in the information collection device 4. In this case, the CPU exhibits functions as the imaging data analysis unit 401 and the irradiation condition setting unit 402 by operating according to a predetermined program read into the memory.

  As shown in FIG. 2, the imaging device 1 and the illumination device 2 are directly connected by a predetermined signal line. In this case, the imaging device 1 outputs a predetermined synchronization signal (trigger) to the illumination device 2 at the start of the imaging process. The illumination device 2 irradiates only during the exposure time of the imaging process by the imaging device 1 in response to the input of the synchronization signal. Thereby, the illuminating device 2 can suppress power consumption rather than the case where it always irradiates.

[Configuration of lighting device]
FIG. 3 is a diagram illustrating the structure of the illumination device according to the first embodiment.
As shown in FIG. 2, the lighting device 2 according to the present embodiment has a configuration in which a planar light emitting unit 21 is provided on the front surface of a substantially rectangular housing 20. The light emitting unit 21 is configured by arranging a large number of infrared LEDs 21a capable of emitting light in the infrared wavelength region on one surface of a planar mounting substrate 21b. The light emitting unit 21 can irradiate a predetermined irradiation range (an irradiation range A described later) by supplying a direct current to the infrared LED 21a. The light emitting unit 21 includes nine plate-like light source units 210 that are divided into lattice-like small regions by three sections vertically and horizontally. The nine light source units 210 are integrally formed on a single mounting board 21b. However, as will be described later, the current adjustment unit 23 (FIG. 4) independently converts the infrared light source 210 to each of the light source units 210. The emission intensity can be adjusted. Here, “emission intensity” is a degree of intensity of light emitted from the light source unit 210 (that is, the infrared LED 21a), and a general physical quantity is indicated by “radiant flux” (unit: W) or the like. Is. When the light source unit 210 emits visible light, the “light emission intensity” may be indicated by “light flux” (unit: lumen) or the like.
The plurality of light source units 210 irradiate each of irradiation sections (irradiation sections a1 to a9 described later) obtained by dividing the irradiation range A of the illumination device 2 into a plurality of parts.

FIG. 4 is a diagram illustrating a functional configuration of the illumination device according to the first embodiment.
As illustrated in FIG. 4, the lighting device 2 according to the present embodiment includes a planar light emitting unit 21, a setting input unit 22, a current adjustment unit 23, and a power supply unit 24 inside the housing 20. .

  As shown in FIG. 3, the light emitting unit 21 includes nine plate-like light source units 210. Each light source unit 210 constituting the light emitting unit 21 emits light (radiates infrared light) when supplied with a direct current from the current adjusting unit 23. Note that the light emission intensity of the light source unit 210 (infrared LED 21a) increases or decreases in proportion to the supplied direct current.

  The setting input unit 22 is a communication module that accepts input of irradiation condition information D from the information collection device 4 via wired or wireless. Here, in the present embodiment, the irradiation condition information D indicates a direct current value for adjusting the light emission intensity for each light source unit 210. When receiving the input of the irradiation condition information D, the setting input unit 22 immediately reflects the direct current value indicated by the irradiation condition information D as a direct current value to be newly supplied.

The current adjustment unit 23 generates a direct current based on the power supplied from the power supply unit 24 and supplies the direct current to each light source unit 210. Here, the current adjustment unit 23 supplies the direct current value set for each light source unit 210 in the setting input unit 22 (the direct current value indicated in the input irradiation condition information D) to the corresponding light source unit 210. To do.
With the above configuration, the lighting device 2 can receive the irradiation condition information D and independently adjust the emission intensity, which is the irradiation condition of each of the nine light source units 210 from the outside.

  The power supply unit 24 supplies the current adjustment unit 23 with the power that is the source of irradiation. The power supply unit 24 includes, for example, a power receiving circuit that receives power input from a connected external power system, a rectifier circuit that generates DC power, and the like. Moreover, the electric power supply part 24 may supply electric power from the internal storage battery.

FIG. 5 is a diagram for explaining an irradiation range of the illumination device according to the first embodiment.
As shown in FIG. 5, the imaging device 1 is arranged in the attachment column 3 so that an imaging range R that is within a predetermined range on the road surface S of the lane 102 can be captured. Moreover, the illumination device 2 is arranged so that the irradiation range A that covers the entire imaging range R of the imaging device 1 can be irradiated on the mounting column 3 together with the imaging device 1.

The nine plate-like light source units 210 (see FIG. 3) constituting the light emitting unit 21 of the illumination device 2 mainly irradiate the nine irradiation sections a1 to a9 included in the irradiation range A, as shown in FIG. To do. As described above, since the illumination device 2 can adjust the light emission intensity for each light source unit 210, the illumination intensity of the irradiation sections a1 to a9 corresponding to each of the light source units 210 can be individually adjusted. Here, each light source part 210 of the illuminating device 2 irradiates each irradiation so that the imaging device 1 can obtain a clear image of the vehicle in the entire range of the irradiation sections a1 to a9 (that is, the entire range of the imaging range R). Conditions are adjusted.
In the following description, the supply current for each light source unit 210 is based on each supply current value [A] in a state where the illuminance of the entire range of the irradiation sections a1 to a9 is adjusted to be substantially uniform (100 %), And the magnitude relationship is expressed as a percentage [%].

[Function of imaging data analysis unit]
6 and 7 are a first diagram and a second diagram illustrating functions of the imaging data analysis unit according to the first embodiment.
As described above, the imaging data analysis unit 401 according to the present embodiment determines whether or not a license plate is captured in the imaging data P, and when the license plate is captured, the position of the license plate is determined. And an imaging state is acquired.
FIG. 6 shows an example of the imaging data P captured by the imaging device 1 at a certain time. In this imaging data P, an ordinary automobile 101a traveling in the right lane and a large vehicle 101b traveling in the left lane are imaged. Hereinafter, details of processing performed on the imaging data P will be described.

The position specifying unit 401a extracts a license plate image while performing image processing such as edge detection on the imaging data P shown in FIG. As a result, the position specifying unit 401a specifies the position (imaging position) where the license plates of the vehicles 101a and 101b are imaged on the imaging data P (see markers Ma and Mb shown in FIG. 6).
Next, the position specifying unit 401 a specifies the position of each license plate on the road surface S of the lane 102 from the imaging position of the license plate (the positions of the markers Ma and Mb on the imaging data P). Here, the position specifying unit 401a stores in advance a correspondence relationship between the imaging position on the imaging data P and the position in the imaging range R (see FIG. 5) of the imaging device 1. The position specifying unit 401a estimates the mounting height of the license plate for each vehicle according to the vehicle type and the like, and based on the imaging position on the imaging data P of the license plate and the correspondence relationship, the lens of the imaging device 1 A straight line connecting the principal point position and the license plate is specified. And the position specific | specification part 401a specifies the position on the road surface S from which the distance from the road surface S becomes the estimated height of the license plate on the specified straight line. Thereby, the position specifying unit 401a determines which of the irradiation sections a1 to a9 (see FIG. 5) on the road surface S of the lane 102 the license plate specifying the imaging position in the imaging data P belongs to. . For example, the position specifying unit 401a determines that the license plate indicated by the marker Ma belongs to the irradiation section a6 and that the license plate indicated by the marker Mb belongs to the irradiation section a1 (see FIG. 6).
Although the number plate mounting height for the vehicle is strictly different for each vehicle, in practice, the number plate is mounted at a substantially constant height for each vehicle type. Therefore, the position specifying unit 401a estimates the mounting height by referring to a predetermined estimated value determined in advance for each vehicle type, for example.

  Next, the imaging state determination unit 401b acquires the imaging state of the license plate specified by the position specification unit 401a. Here, the “imaging state” is an index indicating the degree of whether or not the license plate is clearly imaged. In addition, the state of being “clearly imaged” specifically refers to the background of the plate and the characters to the extent that the vehicle number drawn on the license plate can be correctly extracted by the OCR process in the imaging data P. The contrast is obtained.

  The imaging state determination unit 401b extracts an area in which the license plate to be analyzed is imaged from the imaging data P, and acquires a density distribution for each pixel constituting the area. Then, two densities of the density La of the pixels constituting the background of the license plate and the density Lb of the pixels constituting the drawn character are detected as main density distributions constituting the area (FIG. 7). (See (a) to (c)). Here, the imaging state determination unit 401b acquires the density distribution of all pixels in the target region, and calculates the average values of the two main types of densities as the densities La and Lb, respectively.

When the density difference | La−Lb | between the density La and the density Lb is equal to or greater than the first threshold Lth1, the imaging state determination unit 401b assumes that the characters drawn on the license plate are clearly imaged. The imaging state is determined to be “good” (see FIG. 7A).
On the other hand, when the density difference | La−Lb | between the density La and the density Lb is less than the first threshold value Lth1, and both the density La and the density Lb are less than the second threshold value Lth2. The imaging state determination unit 401b determines that the imaging state is “dark” on the assumption that characters are not clearly captured because the intensity of the received light is insufficient (see FIG. 7B).
Further, when the density difference | La−Lb | between the density La and the density Lb is less than the predetermined threshold value Lth and both the density La and the density Lb are equal to or greater than the second threshold value Lth2, The imaging state determination unit 401b determines that the imaging state is “bright” on the assumption that characters are not clearly captured because the intensity of received light is too strong (see FIG. 7C).
When the imaging state determination unit 401b determines that the imaging state is “good”, the vehicle information extraction unit 401c immediately performs an OCR process to extract information such as a vehicle number.

  Through the processing described above, the imaging state determination unit 401b determines that the imaging state is “dark” for the license plate indicated by the marker Ma in the example illustrated in FIG. Determines that the imaging state is “good” (see FIG. 6).

[Processing flow of information collection device]
FIG. 8 is a flowchart showing a processing flow of the information collecting apparatus according to the first embodiment.
Hereinafter, the processing flow of the information collection device 4 according to the present embodiment will be described in order.
As illustrated in FIG. 8, first, the imaging data analysis unit 401 of the information collection device 4 acquires the imaging data P generated by the imaging device 1 via the communication unit 400 (step S01), and then the imaging data P The analysis process is performed (step S02). Specific analysis processing performed by the imaging data analysis unit 401 in step S02 is as described above with reference to FIGS. By this analysis processing, the imaging data analysis unit 401, for each license plate imaged in the imaging data P, the position (irradiation sections a1 to a9), the imaging state (“good”, “dark” or “bright”), Is identified. When the imaging state is “good”, the imaging data analysis unit 401 (vehicle information extraction unit 401c) performs processing for extracting vehicle number information and the like.

Next, the irradiation condition setting unit 402 according to the present embodiment repeatedly performs the process described below for each license plate extracted in the imaging data P (step S03: NO).
First, the irradiation condition setting unit 402 determines an imaging state for one extracted license plate (step S04). When the imaging state is “good” (step S04: “good”), for the license plate, the imaging data analysis unit 401 has already completed extraction processing of vehicle number information and the like in step S02. Therefore, the irradiation condition setting unit 402 does not perform any particular processing.

On the other hand, when the imaging state is determined to be “dark” (step S04: “dark”), the irradiation condition setting unit 402 refers to the irradiation sections a1 to a9 to which the position of the target license plate belongs, and Irradiation condition information D for increasing the light emission intensity of the light source unit 210 corresponding to the irradiation section is created (step S05).
For example, the license plate indicated by the marker Ma in FIG. 6 belongs to the irradiation section a6, and the imaging state is determined to be “dark”. In this case, the irradiation condition setting unit 402 creates irradiation condition information D in which the supplied direct current is changed from 100% to 200%, for example, so as to increase the light emission intensity of the light source unit 210 corresponding to the irradiation section p6. .
When the imaging state is determined to be “bright” (step S04: “bright”), the irradiation condition setting unit 402 refers to the irradiation sections a1 to a9 to which the position of the target license plate belongs, and Irradiation condition information D for reducing the light emission intensity of the light source unit 210 corresponding to the irradiation section (for example, changing the supplied direct current from 100% to 50%) is created (step S06).

  The irradiation condition setting unit 402 illuminates the newly created irradiation condition information D via the communication unit 400 when the processing of steps S04 to S06 is completed for all extracted license plates (step S03: YES). The data is output to the device 2 (step S07), and the series of processes is terminated. Note that when no license plate is captured in the imaging data P acquired in step S01, the irradiation condition setting unit 402 may omit the process in step S07.

  The information collection device 4 that has completed the processing executes the processing flow again, acquires new imaging data P generated by the imaging device 1 (step S01), and repeats the subsequent processing.

[Function and effect]
According to the above-described processing, the information collection device 4 realizes feedback control that adjusts the illuminance at an appropriate position (irradiation section) in accordance with the imaging state of the license plate acquired for the first time. For example, the position of the license plate that is determined to be “dark” in the first imaging is brightly illuminated. Thereby, in the second imaging, the probability that the license plate is clearly imaged is improved.

  Further, as described above, the illumination device 2 according to the present embodiment can adjust the illuminance for each small region (irradiation section) to which the position of the license plate belongs. Therefore, even if a plurality of vehicles are imaged within the imaging range R, it is possible to set irradiation conditions suitable for each license plate of each vehicle. For example, even when a “dark” license plate and a “bright” license plate are imaged simultaneously in one imaging data P, the emission intensity is increased or decreased for each irradiation section to which each license plate belongs. Thus, both of them can be imaged clearly at the same time.

As described above, the license plate recognition system 100 according to the present embodiment includes the imaging device 1, the illumination device 2, the position specifying unit 401a, the imaging state determination unit 401b, and the irradiation condition setting unit 402. Is incorporated.
According to such an illumination system, the illuminance for each irradiation section is appropriately adjusted based on the state information of the vehicle traveling on the road surface S (that is, the imaging state of the license plate imaged by the first imaging process). Therefore, clear imaging data of the license plate can be acquired for more vehicles regardless of the material and surface state of the license plate for each vehicle.

  Note that the license plate recognition system 100 according to the present embodiment has been described as having one imaging device 1 and one illumination device 2, but is not limited to this aspect in other embodiments. That is, the license plate recognition system 100 may include two or more imaging devices 1 or lighting devices 2. In this case, the position specifying unit 401 a specifies which irradiation section a <b> 1 to a <b> 9 for each irradiation range A by the plurality of illumination devices 2 the position of the license plate imaged in the imaging data P belongs to. Further, the irradiation condition setting unit 402 creates a plurality of irradiation condition information D corresponding to each of the plurality of illumination devices 2 based on the position of the license plate specified by the position specifying unit 401a, and the irradiation condition information D is generated. Output to each of the corresponding lighting devices 2.

In addition, the imaging state determination unit 401b according to the present embodiment displays the license plate imaging state in the imaging data P in three ways: “good”, “dark”, and “bright” according to the density distribution of the pixels constituting the image. However, the present invention is not limited to this aspect in other embodiments. For example, the imaging state determination unit 401b according to another embodiment sets the threshold values (first threshold value Lth1, second threshold value Lth2 (see FIG. 7)) that are the determination criteria of the imaging state in more detail, and the type of classification ( For example, “slightly dark”, “slightly bright”, etc.) may be increased. Further, in this case, the irradiation condition setting unit 402 may change the degree of change of the emission intensity (DC current to be supplied) according to the type of the classification. For example, the irradiation condition setting unit 402 changes the direct current supplied to the corresponding light source unit 210 from 100% to 125% when the target license plate is “slightly dark”, and 100% to 150% when it is “dark”. You may make it change to. By doing in this way, since more exact irradiation conditions are set according to the imaging state classified in detail, the probability that a license plate can be imaged further improves further.
When the light emission intensity for each light source unit 210 can be adjusted more finely, the irradiation condition setting unit 402 uses the densities La and Lb and the density difference | La−Lb | acquired by the imaging state determination unit 401b. The irradiation condition (supplied DC current) may be calculated using a predetermined function as a variable.

  Further, in the above-described embodiment, the lighting device 2 has an example in which the planar light emitting unit 21 is configured by nine plate-like light source units 210 that are divided into three vertical and horizontal sections (3 × 3). However, in other embodiment, it is not limited to such an aspect. For example, the light emitting unit 21 of the lighting device 2 according to another embodiment may be divided into a smaller number of sections such as 2 × 2, 3 × 2, or divided into a larger number of sections such as 4 × 3. May be. In addition, the plurality of light source units 210 are not necessarily arranged in a grid pattern, and for example, a plurality of light source units 210 may be arranged only in one vertical or horizontal row, or arranged in a staggered manner in the light emitting unit 21. Also good.

<Second Embodiment>
Next, a license plate recognition system according to the second embodiment will be described.
The license plate recognition system 100 according to the first embodiment identifies an area (irradiation sections a1 to a9) to which the license plate of the vehicle 101 actually belongs, and determines the emission intensity of the light source unit 210 corresponding to the area as the license plate. In the above description, the adjustment is made according to the imaging state. However, since the vehicle 101 is always traveling, the position of the license plate when the first imaging data P is acquired and the position of the license plate when the second (after feedback) imaging data P is acquired. Therefore, it is assumed that the illuminance zones a1 to a9 to be adjusted are changed and the feedback control does not function as intended for some vehicles 101.
Therefore, the license plate recognition system 100 according to the second embodiment is based on the traveling speed v of the vehicle 101, and is an area (irradiation sections a1 to a9) to which the license plate of the vehicle 101 belongs in the second and subsequent imaging. ) Is specified, and the light emission intensity of the light source unit 210 corresponding to the region based on the estimation is adjusted.

Since the overall configuration and functional configuration of the license plate recognition system 100 according to the second embodiment are the same as those in the first embodiment (FIGS. 1 and 2), illustration is omitted. However, the position specifying unit 401a of the imaging data analysis unit 401 according to the present embodiment is based on the imaging data P acquired by the first imaging and the traveling speed v of the vehicle 101. Estimate the license plate position.
Hereinafter, specific functions of the position specifying unit 401a according to the present embodiment will be described.

[Function of imaging data analysis unit]
FIG. 9 is a diagram illustrating the function of the imaging data analysis unit according to the second embodiment.
The position specifying unit 401a of the imaging data analysis unit 401 according to the present embodiment is based on the position (imaging position) where the license plate is imaged in the imaging data P and the vehicle speed information Dv of the vehicle 101 having the license plate. The position of the license plate on the road surface S at the time of the next imaging is specified.

  Specifically, as illustrated in FIG. 9, the position specifying unit 401a extracts the imaging position of the license plate NP1 of the vehicle 1011 from the imaging data P1 generated by the first imaging, and the road surface S of the license plate NP1. Specify the position on the top. This process is equivalent to the position specifying unit 401a according to the first embodiment.

Next, the position specifying unit 401a according to the present embodiment acquires the traveling speed information Dv of the vehicle 1011 that is grasped in advance, and the vehicle at the time of the second imaging by the imaging device 1 based on the traveling speed information Dv. The position of 1011 (the position of the vehicle 1012 shown in FIG. 9) is estimated. Here, assuming that the traveling speed indicated by the traveling speed information Dv is v and the time interval of imaging by the imaging apparatus 1 is Δt, the position specifying unit 401a travels within the time interval until the next imaging (estimated traveling). The distance Δd) is calculated by Δd = v × Δt. Then, the position specifying unit 401a adds the estimated travel distance Δd to the traveling direction of the vehicle 1011 with respect to the current position (position of the license plate NP1 shown in FIG. 9) to estimate the position (of the license plate NP2 shown in FIG. 9). Position). Further, the position specifying unit 401a specifies the irradiation sections a1 to a9 to which the specified estimated position belongs. In the example shown in FIG. 9, since the license plate NP2 of the vehicle 1012 belongs to the irradiation section a9, the position specifying unit 401a specifies the irradiation section a9.
The irradiation condition setting unit 402 changes the irradiation condition of the light source unit 210 corresponding to the irradiation sections a1 to a9 specified by the position specifying unit 401a based on the estimated travel distance Δd. Further, the irradiation condition setting unit 402 changes the irradiation condition according to the imaging state of the license plate as in the first embodiment.

  In the present embodiment, the traveling speed v indicated by the traveling speed information Dv is acquired by, for example, measuring the average speed of the vehicle in the lane 102 in advance.

[Function and effect]
According to the above-described imaging data analysis unit 401 (position specifying unit 401a), the position of the license plate at the time of the second imaging is estimated based on the position of the license plate acquired at the first time, and the estimated position Feedback control that adjusts the illuminance of (irradiation section) is realized. For example, even if the position of the license plate at the time of the first imaging belongs to the irradiation section a6, when the position of the license plate at the next (second time) imaging is estimated to belong to the irradiation section a9, Feedback is performed on the light emission intensity of the light source unit 210 corresponding to the irradiation section a9, and the second imaging is performed. Thereby, the probability that the license plate is clearly imaged in the second imaging is further improved.

  As described above, according to the license plate recognition system according to the second embodiment, it is possible to realize highly accurate feedback control by considering the movement of the vehicle (number plate) from the first imaging to the second and subsequent imaging. Therefore, clear imaging data of the license plate can be acquired for more vehicles.

<Modification of Second Embodiment>
The imaging data analysis unit 401 (position specifying unit 401a) according to the second embodiment described above is a number at the time of the next imaging based on the traveling speed (average speed, etc.) of the vehicle previously grasped by the previous measurement or the like. It was described as estimating the position of the plate. However, actually, the traveling speed of each vehicle 101 traveling on the lane 102 varies depending on the degree of congestion of the lane 102 and the like. Then, when the position of the license plate is estimated based on the uniformly determined traveling speed v (average speed or the like), it may be assumed that the estimation accuracy is lowered for some vehicles 101.
Therefore, the imaging data analysis unit 401 according to the modification of the second embodiment calculates the actual traveling distance dr of the vehicle 101 that has traveled between the two imaging processes, and based on the calculated traveling distance dr. Thus, the position of the license plate at the next imaging is estimated.

The position specifying unit 401a of the imaging data analysis unit 401 according to this modification acquires two imaging data P1 and P2 generated by two consecutive imaging processes, and each of the two imaging data P1 and P2 is acquired. The actual travel distance dr of the vehicle 101 is calculated from the difference in the position of the number plate picked up at (1). Then, the position specifying unit 401a estimates the position of the license plate at the time of the next (third) imaging based on the calculated travel distance dr.
Hereinafter, specific functions of the position specifying unit 401a according to the present embodiment will be described.

[Function of imaging data analysis unit]
FIG. 10 is a diagram illustrating the function of the imaging data analysis unit according to a modification of the second embodiment.
As described above, the position specifying unit 401a of the imaging data analysis unit 401 according to the present modification calculates the actual travel distance dr of the vehicle 101 based on the two imaging data P1 and P2, and the number at the next imaging. The position of the plate on the road surface S is specified.

  Specifically, first, the position specifying unit 401a acquires two pieces of imaging data P1 and P2 generated by the first and second imaging of the imaging device 1. Then, the position specifying unit 401a specifies the position of the license plate NP1 on the road surface S from the imaging position of the license plate NP1 of the vehicle 1011 in the first imaging data P1. Similarly, the position specifying unit 401a specifies the position of the number plate NP2 on the road surface S from the imaging position of the license plate NP2 of the vehicle 1012 in the second imaging data P2 (see FIG. 10). Note that these processes are equivalent to the processes of the position specifying unit 401a according to the first embodiment.

Next, the position specifying unit 401a calculates the difference between the specified position of the license plate NP1 and the position of the license plate NP2 (that is, the travel distance dr from the first imaging to the second imaging). Subsequently, the position specifying unit 401a adds the travel distance dr to the current position (the position of the license plate NP2 shown in FIG. 10) in the traveling direction of the vehicle 1012 to obtain the estimated position (the vehicle 1013 and the number shown in FIG. 10). The position of the plate NP3 is specified. The positions of the vehicle 1013 and the license plate NP3 obtained in this way are the positions of the vehicle and the license plate that are estimated to be reached at the time of the third imaging.
Further, the position specifying unit 401a specifies the irradiation sections a1 to a9 to which the specified estimated position belongs. In the example shown in FIG. 10, since the license plate NP3 of the vehicle 1013 belongs to the irradiation section a9, the position specifying unit 401a specifies the irradiation section a9.

[Function and effect]
As described above, the imaging data analysis unit 401 (position specifying unit 401a) calculates the actual travel distance dr of the vehicle 101 based on the difference between the positions of the license plates NP1 and NP2 acquired the first time and the second time. . Then, based on the actual travel distance dr of the vehicle 101 obtained by the first and second imaging, the position specifying unit 401a calculates the position of the license plate at the next (third) imaging. Here, the travel distance dr specified by the position specifying unit 401a is a numerical value that reflects the actual travel speed of the traveling vehicle 101. Therefore, the position specifying unit 401a can accurately estimate the position at the time of the next imaging for a vehicle traveling at any traveling speed. Thereby, the probability that the traveling license plate is clearly imaged is further improved.

  As described above, according to the license plate recognition system according to the modified example of the second embodiment, the travel distance for each traveling vehicle is calculated from the first and second imaging data, and the vehicle (number in the third and subsequent imaging) is calculated. By accurately estimating the position of the plate, feedback control with higher accuracy can be realized. Therefore, clear imaging data of the license plate can be acquired for more vehicles.

Note that the information collection device 4 (irradiation condition setting unit 402) according to the first and second embodiments described above performs irradiation conditions at the next imaging based only on the imaging state of the license plate obtained by the previous imaging. Was explained as a change. However, the irradiation condition setting unit 402 according to another embodiment is not limited to this aspect. For example, the irradiation condition at the next imaging is changed based on a plurality of imaging states obtained by one or more previous imaging processes. It is good also as what to do.
Specifically, the irradiation condition setting unit 402 according to the other embodiment includes the imaging data Pα acquired two times before and the imaging data Pβ acquired one time before for the same vehicle 101. Based on the imaging state of the license plate in both and the irradiation conditions when the imaging data Pα and Pβ are imaged, a process for adjusting the irradiation conditions more optimally is performed.

  For example, in the imaging data Pα at a certain time point (first time), the imaging state of the license plate is “dark”, so the irradiation condition setting unit 402 changes the irradiation condition (light emission intensity) from 100% to 200%. However, in the next (second) imaging data Pβ, the license plate imaging state is “bright”, and vehicle number information cannot be extracted. That is, in this case, the feedback control of the irradiation condition changed in the second imaging process is too strong, and the illuminance is too bright. Therefore, at the time of the third imaging, the irradiation condition setting unit 402 changes the irradiation condition (emission intensity) to 150%, which is an intermediate value between 100% and 200%, for example.

  Thus, according to the license plate recognition system 100 according to the other embodiment, in the next (third and subsequent) imaging based on a plurality of imaging states acquired one or more times before for the same vehicle 101. A process is performed to match the irradiation conditions that ensure that clear imaging data can be acquired. As a result, the feedback control is performed so that the irradiation condition is finally optimized through a plurality of imaging operations, so that the probability of clearly imaging the license plate can be further improved.

  In addition, although the above-mentioned position specific | specification part 401a demonstrated as what calculates the driving distance dr of the vehicle 101 based on the position of license plates NP1 and NP2 acquired in the 1st time and the 2nd time, in other embodiment. Is not limited to this embodiment. For example, the position specifying unit 401a according to another embodiment may acquire two images showing the head portion of the vehicle and calculate the travel distance dr based on the difference in the imaging position of the head portion. . By doing in this way, the travel distance dr can be acquired before the license plate enters the imaging range, and more rapid feedback processing can be realized. Similarly, the position specifying unit 401a may calculate the travel distance dr based on the difference in the imaging position of a part that moves in the same manner as the vehicle, such as another specific part of the vehicle or the shadow of the vehicle.

<Third Embodiment>
Next, a license plate recognition system according to the third embodiment will be described.
The license plate recognition system 100 according to the first and second embodiments includes a light source unit 210 corresponding to a region (irradiation sections a1 to a9) to which the license plate of the vehicle 101 currently belongs, or a region based on estimation considering travel. In the above description, the emission intensity is adjusted according to the imaging state of the license plate.
On the other hand, the license plate recognition system 100 according to the third embodiment adjusts the irradiation condition (light emission intensity) of the illuminating device 2 (light source unit 210) based on the vehicle type information acquired from the separately provided vehicle type discriminating means. To do.

[overall structure]
FIG. 11 is a diagram illustrating an overall configuration of a license plate recognition system according to the third embodiment.
As shown in FIG. 11, the license plate recognition system 100 according to the present embodiment newly includes a wireless communication device 6 as a vehicle type discrimination unit. The wireless communication device 6 is attached to the attachment column 3 together with the imaging device 1 and the illumination device 2.
The wireless communication device 6 performs wireless communication with an on-vehicle device (on-vehicle device 101D described later) mounted on the vehicle 101, and acquires information (on-vehicle device information E) necessary for billing processing or the like from the on-vehicle device. The wireless communication device 6 outputs the acquired in-vehicle device information E to the information collecting device 4, and the information collecting device 4 performs a predetermined charging process based on the on-vehicle device information E.

In the present embodiment, the communicable range of the wireless communication device 6 is set to an area on the near side of the mounting column 3 in the lane 102 (an area before the vehicle 101 passes through the mounting column 3). On the other hand, the imaging range R of the imaging device 1 and the irradiation range A of the illuminating device 2 are in a region on the back side in the lane 102 (region after the vehicle 101 passes through the mounting column 3), as in the above-described embodiments. The rear surface including the license plate can be imaged from the rear side in the traveling direction of the vehicle 101 that is set and travels on the lane 102. Thereby, in the license plate recognition system 100 according to the present embodiment, the traveling vehicle 101 is imaged by the imaging device 1 after completing the charging process or the like by wireless communication.
In the present embodiment, a specific aspect of the billing process performed by the wireless communication device 6 and the vehicle-mounted device is, for example, a conventional electronic toll collection system (ETC: Electronic Toll Collection System (registered trademark)) or It may also be called “automatic fee collection system”).

[Functional structure of license plate recognition system]
FIG. 12 is a diagram illustrating a functional configuration of a license plate recognition system according to the third embodiment. In this figure, the same functional configurations as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 12, the license plate recognition system 100 according to the present embodiment includes a vehicle-mounted device 101D mounted on a traveling vehicle 101 and a wireless communication device 6 mounted on the mounting column 3 (FIG. 1). Communication is performed, information recorded in the vehicle-mounted device 101D (vehicle-mounted device information E) is acquired, and the vehicle-mounted device information E is output to the information collecting device 4.

In the vehicle-mounted device 101D, registered vehicle type information and registered vehicle number information about the vehicle 101 are recorded in advance. Here, the registered vehicle type information is information indicating the vehicle type classification (light vehicle, ordinary vehicle, large vehicle, etc.) of the vehicle 101, and the registered vehicle number information is information indicating the vehicle number of the vehicle 101. In addition, a dedicated IC card used for electronic payment is inserted into the vehicle-mounted device 101D. This dedicated IC card records electronic payment information (card identification information, personal information) and the like necessary for electronic payment.
The wireless communication device 6 acquires registered vehicle type information, registered vehicle number information, and electronic payment information recorded on the dedicated IC card by wireless communication with the vehicle-mounted device 101D.

The information collection device 4 according to the present embodiment includes a billing processing unit 404 and a vehicle type identification unit 405 in addition to the imaging data analysis unit 401 and the irradiation condition setting unit 402.
The imaging data analysis unit 401 according to the present embodiment includes only the vehicle information extraction unit 401c, extracts vehicle number information and the like from the imaging data P generated by the imaging device 1, and stores and stores the vehicle number information in the storage unit 403.
The irradiation condition setting unit 402 according to the present embodiment changes the irradiation condition of the lighting device 2 according to the vehicle type specified by the vehicle type specifying unit 405 described later for the vehicle 101. Specific irradiation condition changing processing by the irradiation condition setting unit 402 will be described later.

  The billing processing unit 404 performs electronic payment processing based on the on-vehicle device information E acquired from the on-vehicle device 101D via the wireless communication device 6. Specifically, when the registered vehicle type information, registered vehicle number information, and electronic payment information described above are input from the wireless communication device 6, the billing processing unit 404 calculates a fee to be collected based on these information. And perform electronic payment processing. Then, the billing processing unit 404 creates usage details information and traffic history information, performs transmission to the card issuer, recording on the dedicated IC card, and the like, and completes the electronic payment processing.

  The vehicle type identification unit 405 identifies the vehicle type of the vehicle 101 based on the registered vehicle type information among the vehicle-mounted device information E (registered vehicle type information, registered vehicle number information, electronic payment information) used by the charging processing unit 404 for the accounting process. To do. The vehicle type identification unit 405 outputs vehicle type identification information indicating the vehicle type identified for the vehicle 101 to the irradiation condition setting unit 402.

FIG. 13 is a flowchart illustrating a processing flow of the information collection apparatus according to the third embodiment.
Hereinafter, the processing flow of the information collection device 4 according to the present embodiment will be described in order.
The processing flow shown in FIG. 13 is started when the vehicle 101 equipped with the vehicle-mounted device 101D travels on the lane 102 and enters the communicable range of the wireless communication device 6.

First, the billing processing unit 404 and the vehicle type identification unit 405 of the information collection device 4 are connected to the vehicle-mounted device information E (registered vehicle type information, registered vehicle) recorded in the vehicle-mounted device 101D of the vehicle 101 via the wireless communication device 6 and the communication unit 400. Number information, electronic payment information) is acquired (step S11).
When the billing processing unit 404 acquires the in-vehicle device information E, the billing processing unit 404 immediately performs billing processing. Further, the vehicle type identification unit 405 identifies the vehicle type of the vehicle 101 based on the registered vehicle type information included in the in-vehicle device information E (step S12). The vehicle type identification unit 405 further outputs vehicle type identification information indicating the identified vehicle type to the irradiation condition setting unit 402.

The irradiation condition setting unit 402 according to the present embodiment refers to the vehicle type identification information received from the vehicle type identification unit 405 (step S13), and performs a process according to the vehicle type indicated by the vehicle type identification information.
Here, when the vehicle type of the vehicle 101 is “ordinary vehicle” (step S13: “ordinary vehicle”), the irradiation condition setting unit 402 optimizes the irradiation condition of the illuminating device 2 for a normal vehicle. Irradiation condition information D as Ta is created (step S14). Here, the “irradiation condition type Ta” is a basic irradiation condition (for example, an irradiation condition in which the direct current supplied to all the light source units 210 is “100%”) of the lighting device 2 that is employed during normal operation. . Thereby, the imaging device 1 can image the license plate attached to the “ordinary vehicle” clearly with high probability.

  On the other hand, when the vehicle type of the vehicle 101 is “two-wheeled vehicle” (step S13: “two-wheeled vehicle”), the irradiation condition setting unit 402 performs irradiation with the irradiation condition type Tb optimized for the two-wheeled vehicle. Condition information D is created (step S15). Here, the “irradiation condition type Tb” means an irradiation condition (for example, a direct current supplied to all the light source units 210 that is lower than the basic irradiation condition (irradiation condition type Ta) “50%”. Irradiation conditions). That is, since the number plate is often mounted upward in a two-wheeled vehicle, the imaging apparatus 1 collects the specularly reflected light, and there is a high probability that clear imaging cannot be performed under the irradiation condition type Ta. Therefore, the irradiation condition setting unit 402 creates irradiation condition information D having a light emission intensity lower than the basic irradiation condition (type Ta) as the irradiation condition Tb optimized in advance for a motorcycle.

  When the vehicle 101 is a “large vehicle” (step S13: “large vehicle”), the irradiation condition setting unit 402 is an irradiation condition type Tc in which the irradiation condition of the lighting device 2 is optimized for a large vehicle. Is created (step S16). Here, the “irradiation condition type Tc” means an irradiation condition (for example, 150% of the direct current supplied to all the light source units 210) that has a light emission intensity higher than the basic irradiation condition (irradiation condition type Ta) as a whole. Irradiation conditions). That is, in a large vehicle, since it is often attached to a slightly deep place such as the lower part of the loading platform, the number plate is often imaged darkly in the shadow of sunlight. Therefore, the probability that a license plate of a large vehicle cannot be clearly imaged increases. Therefore, the irradiation condition setting unit 402 creates irradiation condition information D having an emission intensity higher than the basic irradiation condition (type Ta) as the irradiation condition Tc optimized in advance for a large vehicle.

Next, the irradiation condition setting unit 402 outputs the irradiation condition information D newly created in any of steps S14 to S16 to the illumination device 2 via the communication unit 400 (step S07). When the illumination device 2 (the setting input unit 22 (FIG. 2)) receives the input of the irradiation condition information D, it immediately changes the irradiation condition to one of the irradiation condition types Ta to Tc indicated in the irradiation condition information D. To do.
Next, when the vehicle 101 continues to travel and enters the imaging range R of the imaging device 1, the imaging device 1 generates imaging data P of the vehicle 101 under the newly set irradiation condition. And the imaging data analysis part 401 performs OCR process etc. with respect to the acquired imaging data P, and extracts the vehicle number information etc. of the vehicle 101 (step S18).

[Function and effect]
According to the processing of the information collecting apparatus 4 described above, the imaging data P acquired by the imaging data analysis unit 401 in step S18 is imaged under irradiation conditions optimized according to the vehicle type of the vehicle 101. Therefore, the license plate is imaged with high probability.
As described above, the license plate recognition system 100 according to the present embodiment is connected to the vehicle type discriminating means (in the present embodiment, the vehicle-mounted device 101D and the wireless communication device 6 used in the electronic toll collection system or the like). Thus, the vehicle type for each vehicle 101 is grasped, and the imaging is performed after the irradiation condition of the illumination device 2 is optimized for the vehicle type. By doing in this way, the imaging device 1 can image a license plate under illumination optimized for the vehicle type of the vehicle 101.

As described above, the license plate recognition system 100 according to the present embodiment incorporates an illumination system that includes the vehicle type discrimination means (the vehicle-mounted device 101D and the wireless communication device 6), the illumination device 2, and the irradiation condition setting unit 402. It is set as the mode.
According to such an illumination system, an image is taken under illumination optimized for the vehicle type of the traveling vehicle based on the state information of the vehicle traveling on the road surface S (that is, the vehicle type determined by the vehicle type determining means). Therefore, clear imaging data of the license plate can be acquired for more vehicles.

  In addition, the license plate recognition system 100 according to the present embodiment sets optimal irradiation conditions for the vehicle type of the vehicle 101 from the stage before the vehicle 101 enters the imaging range R. Therefore, the probability that the license plate of the vehicle 101 can be clearly imaged by only one imaging increases, and the processing load on the information collecting device 4 can be reduced.

Note that the license plate recognition system 100 according to the present embodiment is based on registered vehicle type information acquired in advance by wireless communication between the vehicle-mounted device 101D constituting the electronic toll collection system and the wireless communication device 6 as vehicle type determination means. The aspect which specifies the vehicle type for every traveling vehicle 101 has been described. However, the license plate recognition system 100 according to another embodiment is not limited to this mode.
For example, as another vehicle type discriminating means, a vehicle type discriminating device capable of discriminating the vehicle type of a passing vehicle based on various detection signals detected from various sensors such as a vehicle separator, a vehicle type discrimination tread, a vehicle height detector, etc. May be used. In this case, it is assumed that the vehicle type identification device is installed on the front side of the lane 102 (for example, a region before the vehicle 101 passes through the mounting column 3). Then, when the vehicle type determination device performs the vehicle type determination process of the passed vehicle 101, the vehicle type determination device outputs vehicle type determination information indicating the determined vehicle type to the irradiation condition setting unit 402 of the information collection device 4.

  The processing flow shown in FIG. 13 is an example, and is not limited to the case where the above-described irradiation condition types Ta to Tc are applied to each of “ordinary vehicle”, “two-wheeled vehicle”, and “large vehicle”. In other words, the irradiation condition setting unit 402 only needs to have a function that can be changed to an irradiation condition recognized as optimal for each vehicle type by a demonstration experiment or the like performed in advance.

Further, the license plate recognition system 100 according to the present embodiment may be a mode in which the functions of the license plate recognition system 100 according to the first and second embodiments are provided at the same time. In other words, the license plate recognition system 100 changes to the optimum irradiation condition according to the vehicle type acquired in advance, but in the second and subsequent imaging when it is not clearly irradiated in the first imaging. You may perform feedback control of irradiation conditions.
In this case, the information collection device 4 includes an imaging data analysis unit 401 including the position specifying unit 401a and the imaging state determination unit 401b described in the first and second embodiments, and a vehicle type specifying unit 405 according to the present embodiment. It is set as the aspect provided with both.

<Fourth Embodiment>
The irradiation condition setting unit 402 according to the above-described third embodiment has been described as specifying the vehicle type of the vehicle 101 in advance via a predetermined vehicle type determination unit, and changing the irradiation condition to be optimal for the vehicle type. .
On the other hand, the irradiation condition setting unit 402 according to the fourth embodiment changes to the optimal irradiation condition for each time zone based on statistical information indicating the configuration ratio of the vehicle type acquired in advance.

FIG. 14 is a diagram illustrating a functional configuration of a license plate recognition system according to the fourth embodiment. In this figure, the same functional configurations as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 14, the information collection device 4 according to this modification is newly provided with a statistical information storage unit 406. Further, the irradiation condition setting unit 402 according to the present modification has a built-in clock 402 a separately, and refers to the date and time indicated by the built-in clock 402 a and the vehicle type composition ratio statistical information H stored in advance in the statistical information storage unit 406. Set the optimal irradiation conditions for each time zone.

FIG. 15 is a diagram illustrating a statistical information storage unit according to the fourth embodiment.
The statistical information storage unit 406 stores vehicle type composition ratio statistical information H indicating the statistics of the vehicle type composition ratio acquired in advance for each time zone. Here, in the vehicle type composition ratio statistical information H, for example, as shown in FIG. 15, the vehicle type composition ratio for each day of the week and time zone in the lane 102 is recorded. This vehicle type composition ratio statistical information H is statistical information specific to the lane 102 obtained by extracting the number of vehicles used for each vehicle type measured in the past by day of the week (or weekday or holiday) or by time zone. According to the vehicle type composition ratio statistical information H shown in FIG. 15, it is possible to grasp the vehicle type composition ratio of the vehicle 101 for each weekday, holiday, or time zone. In general, since the number of vehicles such as large vehicles greatly varies depending on the lane, the vehicle type composition ratio statistical information H may further record a vehicle type composition ratio for each lane.
The vehicle type composition ratio is a ratio of the number of vehicles of each vehicle type to the total number of vehicles passed by time zone (or lane). Thereby, for example, a change in the composition ratio such as a relatively large proportion of large vehicles can be grasped in the midnight time zone.

FIG. 16 is a flowchart illustrating a processing flow of the information collection apparatus according to the fourth embodiment.
Hereinafter, the processing flow of the information collection device 4 according to this modification will be described in order.

The irradiation condition setting unit 402 performs a process of changing the irradiation condition of the illumination device 2 at regular time intervals (for example, every hour) (step S21). For example, as shown in FIG. 15, when the vehicle type composition ratio for each hour is recorded in the vehicle type composition ratio statistical information H, the irradiation condition setting unit 402 refers to the current time indicated by the built-in clock 402a. A process of changing the irradiation condition is performed with reference to the vehicle type composition ratio statistical information H for each time.
Here, when a predetermined time (for example, 1 hour) has elapsed (step S21: YES), the irradiation condition setting unit 402 changes the vehicle type composition ratio statistical information H recorded in the statistical information storage unit 406 to the current date and time. Corresponding vehicle type composition ratio data h is acquired (step S22).

  Next, the irradiation condition setting unit 402 calculates an optimal irradiation condition based on the acquired vehicle type composition ratio data h (step S23). As an optimal irradiation condition calculation method, the irradiation condition setting unit 402 has an optimal irradiation condition (output intensity determined by a prior demonstration experiment) for each vehicle type (for example, a normal vehicle, a two-wheeled vehicle, a large vehicle). It calculates so that it may become a mixed value according to the composition ratio for every time zone. For example, it is assumed that the optimal emission intensity (supplied direct current) for each of a normal vehicle, a motorcycle, and a large vehicle is 100%, 50%, and 200%, respectively. On the other hand, the vehicle type composition ratio data h acquired by the irradiation condition setting unit 402 is normal vehicle: two-wheeled vehicle: large vehicle = Q1: Q2: Q3 (Q1, Q2, Q3 are values of 0 to 100%, Q1 + Q2 + Q3 = 100%). In this case, the irradiation condition setting unit 402 sets the value calculated by 100% × Q1 + 50% × Q2 + 200% × Q3 as the optimal irradiation condition (light emission intensity). By doing in this way, for example, in a time zone in which a large vehicle occupies a large number, the emission intensity is relatively high, and the irradiation condition approaches the optimal for a large vehicle. Further, in a time zone in which there are many motorcycles, the light emission intensity is relatively low, and the irradiation condition approaches the optimum for the motorcycle.

  The irradiation condition setting unit 402 creates irradiation condition information D indicating the irradiation condition of the lighting device 2 calculated in step S23, and outputs the irradiation condition information D to the lighting device 2 (step S24). When the illumination device 2 (the setting input unit 22 (FIG. 2)) receives the input of the irradiation condition information D, it immediately changes the irradiation condition to the irradiation condition indicated in the irradiation condition information D.

[Function and effect]
According to the processing of the information collecting apparatus 4 described above, in step S23, the optimum irradiation condition according to the vehicle type composition ratio is set for each time zone (and for each weekday and holiday). For example, the irradiation condition setting unit 402 sets the emission intensity relatively high in a time zone in which a large number of large vehicles occupy a large number and approaches the optimal irradiation condition for the large vehicle. The probability of clear imaging increases.

As described above, the license plate recognition system 100 according to the present embodiment includes an illumination system including the statistical information storage unit 406 in which the vehicle type composition ratio statistical information H is recorded, the illumination device 2, and the irradiation condition setting unit 402. It is set as the aspect integrated.
According to such an illumination system, based on the state information of the road surface S (that is, the statistical information indicating the vehicle type composition ratio for each time zone of the vehicle traveling on the road surface S), the irradiation condition of the illumination device 2 is set to the vehicle type. Imaging is performed after optimization according to the composition ratio. By doing in this way, since the illumination system according to the present embodiment performs imaging under illumination optimized according to the vehicle type composition ratio for each time zone, clear imaging of the license plate for more vehicles Data can be acquired.

  In addition, the irradiation condition setting unit 402 according to the present embodiment sets an optimal irradiation condition according to the vehicle type composition ratio every predetermined time (for example, one hour). Therefore, the irradiation conditions of the illumination device 2 are not frequently changed, and the processing load on the information collection device 4 can be reduced.

  In addition, although the irradiation condition setting part 402 mentioned above demonstrated changing to optimal irradiation conditions for every fixed time period (for example, every hour) with reference to the vehicle type composition ratio statistical information H, other The embodiment is not limited to this aspect. For example, the irradiation condition setting unit 402 may change the irradiation condition every predetermined time (for example, 10 am, 5 pm, etc.).

  Moreover, the vehicle type composition ratio statistical information H described above is an example, and is not limited to that shown in FIG. 15 in other embodiments. That is, the irradiation condition setting unit 402 may refer to statistical information or prediction information obtained for a special period such as a large consecutive holiday as well as just a time zone and a holiday.

[Other aspects of lighting device]
In each of the above-described embodiments, as shown in FIG. 3, the illumination device 2 has a plurality of (9) plate-like light source units 210 whose emission intensity can be controlled independently, so that the irradiation range A can be controlled. It demonstrated as an aspect which can adjust illuminance distribution finely according to irradiation division a1-a9. However, the illuminating device 2 which concerns on other embodiment may be the aspect which enables adjustment of the light projection direction for every light source part 210 as irradiation conditions.

17 and 18 are first and second diagrams showing the structure of a lighting device according to another embodiment.
As shown in FIG. 17, the illuminating device 2 according to the other embodiment has a configuration in which a planar light emitting unit 21 is provided inside a substantially rectangular box-shaped housing 20 as in the first embodiment. The light emitting unit 21 is composed of nine plate-like light source units 210 that are divided into lattice-like small regions by three sections vertically and horizontally. The configuration of the light source unit 210 is the same as that of the first embodiment.

  As shown in FIG. 17, each light source part 210 (mounting board 21b) can change the light projection direction independently. Specifically, the mounting board 21b can be rotated to a predetermined angle from the initial arrangement (a plane parallel to the XZ plane in FIG. 6) with the ± X direction and the ± Z direction as axes.

As shown in FIG. 18, each light source unit 210 includes a first axis movable unit 25 and a second axis movable unit 26 on the back surface (surface on the −Y direction side) side of the mounting substrate 21 b.
The first axis movable portion 25 is provided with a horizontal insertion port 25a formed along the ± X direction and a vertical insertion port 25b formed along the ± Y direction. A horizontal insertion shaft 20 a fixed to the housing 20 is inserted into the horizontal insertion port 25 a of the first shaft movable unit 25. Thereby, the 1st axis | shaft movable part 25 can be rotated to the periphery of the extending | stretching direction of the horizontal insertion axis | shaft 20a on the basis of the housing | casing 20. As shown in FIG.
Further, a vertical insertion shaft 26 a that is a part of the second shaft movable portion 26 is inserted into the vertical insertion port 25 b of the first shaft movable portion 25. Thereby, the second axis movable part 26 can be rotated about the axis in the extending direction of the vertical insertion axis 26a with the first axis movable part 25 as a reference. Further, as shown in FIG. 18, the second shaft movable portion 26 is fixed to the back surface side of the mounting substrate 21b with the joint surface 26b.
The mounting substrate 21b is connected to the housing 20 via the first-axis movable unit 25 and the second-axis movable unit 26 described above, so that the direction in which the surface faces is both around the ± X axis and around the ± Y axis. Can be rotated.
The first shaft movable unit 25 and the second shaft movable unit 26 described above are connected to a drive mechanism (gear, stepping motor, etc.) (not shown) and rotated via the drive mechanism by a drive mechanism control unit 23A described later. The position is controlled.

FIG. 19 is a diagram illustrating a functional configuration of a lighting device according to another embodiment.
As illustrated in FIG. 19, the lighting device 2 according to another embodiment includes the drive mechanism 210 </ b> A described above for each light source unit 210. In addition, the illumination device 2 includes a setting input unit 22 that receives an input of irradiation condition information D and sets an irradiation condition, and a drive mechanism control unit 23A that can control each drive mechanism 210A independently. Note that the power supply unit 24 according to the other embodiment supplies a uniform direct current to each light source unit 210.

In the other embodiment, the irradiation condition information D received by the setting input unit A includes setting values (± X axis rotation position θx, ± Y axis rotation position θy) for each drive mechanism 210A. When receiving the irradiation condition information D, the setting input unit 22 outputs the setting values (θx, θy) for each driving mechanism 210A indicated in the irradiation condition information D to the driving mechanism control unit 23A. The drive mechanism control unit 23A, to which the set value for each drive mechanism 210A is input, performs drive control so that each rotational position of each drive mechanism 210A is set to a set value (θx, θy).
Thereby, the illuminating device 2 which concerns on the said other embodiment can change "light projection direction" as desired as an irradiation condition for every light source part 210 based on the irradiation condition information D input.

The license plate recognition system 100 according to the first and second embodiments may perform feedback control using the illumination device 2 according to the other embodiment. Specifically, the irradiation condition setting unit 402 of the information collection device 4 irradiates the license plate when the imaging state of the license plate of the vehicle 101 is “dark” in the process of step S05 (FIG. 8). Irradiation condition information D for changing the light projection direction of each light source unit 210 is created so that the light intensity increases. For example, when the position of the target license plate belongs to the irradiation section a6 (FIG. 5), the irradiation condition setting unit 402 moves the irradiation range of the light source unit 210 that irradiates the irradiation section a3 to the irradiation section a6 side. Thus, the angle of the horizontal insertion shaft 20a is changed. Thereby, since the light from the two light source units 210 is projected onto the irradiation section a6, the intensity of the light irradiated to the license plates belonging to the irradiation section a6 increases.
Similarly, when the imaging state of the license plate of the vehicle 101 is “bright” in the process of step S06 (FIG. 8), the irradiation condition setting unit 402 reduces the intensity of light irradiated on the license plate. In addition, the irradiation condition information D for changing the light projection direction of each light source unit 210 is created. For example, when the position of the target license plate belongs to the irradiation section a6, the irradiation condition setting unit 402 sets the horizontal insertion axis 20a so that the irradiation range of the light source unit 210 that irradiates the irradiation section a3 is away from the irradiation section a6. Change the angle. Thereby, since the light projected from the light source unit 210 corresponding to the irradiation section a3 toward the irradiation section a6 is moved away from the irradiation section a6, the intensity of the light irradiated to the license plates belonging to the irradiation section a6 is reduced.

  As described above, the “irradiation condition” of the illumination device 2 may be not only “light emission intensity” for each light source unit 210 but also “light projection direction”. Further, the illumination device 2 may be configured such that both “light emission intensity” and “light projection direction” can be adjusted as irradiation conditions. In this case, it is assumed that the irradiation condition information D created by the irradiation condition setting unit 402 indicates both the light emission intensity (DC current) and the rotation position setting values (θx, θy) for each light source unit 210. .

In another embodiment, the plurality of light source units 210 that can independently control the light emission intensity or the light projecting direction may not necessarily be provided in a single housing (housing 20). In other words, a plurality of light source units 210 may be provided in each individual housing (illumination device). For example, in FIG. 5, nine housings (lighting devices) are each attached to the mounting support column 3 while having a single light source unit 210, and the light source units 210 for each of the housings are respectively provided in the irradiation sections a1 to a9. May be a mode of irradiating.
In this case, the setting input unit 22, the current adjustment unit 23, or the drive mechanism control unit 23A is provided for each case, and the irradiation condition setting unit 402 outputs the irradiation condition information D for each corresponding case. It may be a thing.
Moreover, the light with which the illumination device 2 irradiates is not limited to infrared light, and may be visible light, for example.

In the first and second embodiments, a functional configuration (position specifying unit 401a, imaging state determination unit 401b, irradiation condition setting unit 402, etc.) for performing feedback control is incorporated in the information collection device 4. Although described as a thing, in other embodiment, it is not limited to this aspect. For example, the position specifying unit 401a, the imaging state determination unit 401b, and the irradiation condition setting unit 402 according to the first and second embodiments may be incorporated in either the imaging device 1 or the illumination device 2. Moreover, the aspect with which another information processing apparatus installed in another area (the roadside of the lane 102, etc.) is provided may be sufficient.

Further, the illumination device 2 may be able to adjust “irradiation time” during the imaging process of the imaging device 1 in addition to the above-described “light emission intensity” and “light projection direction” as the irradiation condition. In this case, the illumination device 2 may be adjusted by combining a part or all of “light emission intensity”, “light projection direction”, and “irradiation time”. Thus, the illuminance distribution in the irradiation range can also be adjusted by adjusting the irradiation time during the imaging process.
Since the adjustment range of the emission intensity itself is finite, a case where a desired illuminance distribution cannot be obtained only by adjusting the emission intensity is assumed. However, as described above, the adjustment range of the illuminance distribution can be expanded by adjusting the “light emission time” as the irradiation condition.

<Fifth Embodiment>
[Irradiation distribution adjustment function]
In each of the above-described embodiments, it is desirable that the illumination device 2 sets the imaging range R of the imaging device 1 to a desired irradiation condition in advance. Therefore, the license plate recognition system 100 according to the fifth embodiment determines the irradiation conditions (light emission intensity, light projection direction, or irradiation time) of the illumination device 2 so that the imaging range R has a desired illuminance distribution. Further, it may have a lighting device adjustment function. In the following description, the license plate recognition system 100 according to the fifth embodiment will be described as an example in which the irradiation distribution adjustment function is added to the license plate recognition system 100 according to the first embodiment. .

[overall structure]
FIG. 20 is a diagram illustrating an overall configuration of a license plate recognition system according to the fifth embodiment.
As shown in FIG. 20, the license plate recognition system 100 includes an imaging device 1, a lighting device 2, a mounting column 3 that supports them, and an information collection device 4 installed in another area.
The license plate recognition system 100 according to the present embodiment is an “irradiation condition adjustment mode” which is an operation mode for supporting the adjustment operation of the irradiation condition of the lighting device 2 in addition to the normal process (vehicle number information collection process). Can be selected.
In this irradiation condition adjustment mode, a plurality of imaging reference members 41 are arranged on the road surface S as shown in FIG. The structure and arrangement of the imaged reference member 41 will be described below.

[Description of imaging reference member]
FIG. 21 is a diagram illustrating the structure of the imaged reference member according to the fifth embodiment.
As shown in FIG. 21, the imaged reference member 41 has an imaged surface 41a formed in a rectangular shape and a support surface 41b that contacts the road surface S and supports the entire housing. The imaging surface 41a and the support surface 41b are integrally formed so as to be bent at a right angle, and the imaging surface 41a stands perpendicular to the road surface S by placing the support surface 41b in contact with the road surface S. Installed.
The imaged surfaces 41a of the imaged reference member 41 installed on the road surface S are made of the same material and surface state, and are formed so as to have the same reflectance. For example, the imaged surface 41a may be made of the same material or surface state as a generally used license plate.

FIG. 22 is a diagram for explaining a method of arranging the imaging target reference member according to the fifth embodiment.
The lighting device according to the present embodiment is the same lighting device as the lighting device according to the first embodiment. That is, the light emitting unit 21 of the lighting device 2 includes nine plate-like light source units 210 that are divided into three vertically and horizontally, and the irradiation condition can be changed independently for each light source unit 210.
For example, the case where the lighting device 2 shown in FIG. In this case, the plurality of light source units 210 constituting the light emitting unit 21 of the illumination device 2 irradiates the corresponding nine irradiation sections a1 to a9 in the irradiation range A. In this case, a plurality of imaging reference members 41 are provided for each of the irradiation sections a1 to a9 in the irradiation range A on the road surface S while being arranged so as to face the imaging surface 41a to be imaged by the imaging device 1. (See FIG. 22). By arranging in this way, each irradiation condition of the plurality of light source units 210 and the imaging state of each imaging target reference member 41 can be associated approximately one-to-one.

[Configuration of information collection device]
FIG. 23 is a diagram illustrating a functional configuration of the information collection device according to the fifth embodiment. In this figure, the same functional configurations as those of the above-described embodiments are denoted by the same reference numerals, and description thereof is omitted.
As shown in FIG. 23, the information collection device 4 according to the present embodiment further includes a mode selection unit 407 and an irradiation condition determination unit 408.

The mode selection unit 407 receives an input operation by an operator via predetermined input means (keyboard, touch panel, etc.), and determines the operation mode of the license plate recognition system 100 according to the input. Specifically, the mode selection unit 407 captures the “vehicle information collection mode” in which the traveling vehicle (number plate) is imaged and the vehicle information and the like are extracted by the operator's input operation, and the irradiation condition of the illumination device 2 The “irradiation condition adjustment mode” for performing the adjustment work can be selected.
When it is desired to perform the adjustment operation of the irradiation condition of the illumination device 2, the worker selects the “irradiation condition adjustment mode” via the input means.

The irradiation condition determination unit 408 receives imaging data P ′ generated by the imaging apparatus 1 via the communication unit 400 when the “irradiation condition adjustment mode” is selected in the mode selection unit 407. Here, the imaging data P ′ is imaging data obtained by imaging a plurality of imaging target reference members 41 arranged on the road surface S. The irradiation condition determination unit 408 acquires the imaging data P ′ obtained by imaging the plurality of imaging target reference members 41, and whether or not the brightness in the area where the imaging surface 41a is imaged is uniform among the imaging data P ′. Determine. In addition, the irradiation condition determination unit 408 notifies the determination result to the operator via a notification means such as a display monitor.
Specific determination processing of the irradiation condition determination unit 408 will be described later.

[Function of irradiation condition judgment unit]
24 and 25 are first and second diagrams illustrating processing of the irradiation condition determination unit according to the fifth embodiment.
Each of FIG. 24 and FIG. 25 shows an example of imaging data P ′ acquired by the imaging apparatus 1 in the irradiation condition adjustment mode. As shown in FIGS. 24 and 25, the imaging surface 41a (FIG. 21) of nine imaging reference members 41 installed on the road surface S is imaged in the imaging data P ′.
The irradiation condition determination unit 408 extracts nine areas (determination areas p1 to p9) in which the imaging target surface 41a is imaged from the imaging data P ′ and 9 determinations for the imaging data P ′. A determination process is performed as to whether or not the brightness of each of the regions p1 to p9 is within a predetermined range (fixed brightness range Bc). The fixed brightness range Bc is determined by a difference (Bc = Bcmax−Bcmin) between a predetermined maximum determination threshold Bcmax and a minimum determination threshold Bcmin.

First, the process of the irradiation condition determination unit 408 when the input of the imaging data P ′ shown in FIG. 24 is received will be described.
When the irradiation condition determination unit 408 receives the input of the imaging data P ′, the imaging target surface of the imaging reference member 41 in the acquired imaging data P ′ through predetermined image processing (for example, edge detection processing or the like). Determination areas p1 to p9, which are areas where 41a is imaged, are extracted. Then, the irradiation condition determination unit 408 calculates the lightness for each of the determination regions p1 to p9 based on the lightness information for each pixel constituting the imaging data P ′.
Here, in the imaging data P ′ shown in FIG. 24, the brightness of the determination areas p1 to p9 in which the imaging surface 41a is imaged is different. Specifically, the determination area p1 has a relatively high brightness, while the determination areas p6 to p9 have a relatively low brightness. In this case, it is assumed that only the brightness of the determination areas p2 to p5 is within a predetermined range (fixed brightness range Bc).
In this case, the irradiation condition determination unit 408 determines that the lightness in the determination region p1 and the determination regions p6 to p9 is not within the fixed lightness range Bc, and does not have a desired illuminance distribution in the imaging region of the imaging device 1. Notify that.

Next, the process of the irradiation condition determination unit 408 when the input of the imaging data P ′ illustrated in FIG. 25 is received will be described.
As in the case of FIG. 24, the irradiation condition determination unit 408 receives the input of the imaging data P ′ and extracts the determination areas p1 to p9 from the acquired imaging data P ′ and also determines the determination areas p1 to p9. The brightness of each is calculated.
Here, in the imaging data P ′ shown in FIG. 25, the brightness of the determination areas p1 to p9 in which the imaging surface 41a is imaged is uniform. In this case, it is assumed that all the brightness values of the determination areas p1 to p9 are within the fixed brightness range Bc.
In this case, the irradiation condition determination unit 408 determines that all the brightness values in the determination areas p1 to p9 are within the fixed brightness range Bc, and notifies that the desired illumination distribution is obtained in the imaging area of the imaging device 1. To do.

[Processing flow of information collection device]
FIG. 26 is a diagram illustrating a processing flow of the information collecting apparatus according to the fifth embodiment.
First, the mode selection unit 407 of the information collection device 4 refers to the currently selected operation mode (step S31). Here, when the “vehicle information collection mode” is selected (step S31: NO), the communication unit 400 of the information collection device 4 uses the information collection device 4 as a normal process of the license plate recognition system 100. A vehicle information collection process is performed (step S32). Here, the vehicle information collection process is, for example, a series of processes (steps S01 to S07 shown in FIG. 8) of the information collection apparatus 4 according to the first embodiment.

On the other hand, when the “irradiation condition adjustment mode” has been selected (step S31: YES), the communication unit 400 receives input of imaging data P ′ from the imaging device 1 (step S33). In this case, in the pre-imaging stage, the imaging reference member 41 is arranged in advance for each irradiation section corresponding to the illumination device 2 to be adjusted, and the imaging data P ′ includes the imaging reference member. 41 imaging surfaces 41a are imaged.
The mode selection unit 407 outputs the input imaging data P ′ to the irradiation condition determination unit 408. The irradiation condition determination unit 408 performs an extraction process of the determination areas p1 to p9 (see FIGS. 24 and 25) and a lightness calculation process in the determination areas p1 to p9 for the imaging data P ′ (Step S34). .

The irradiation condition determination unit 408 determines whether or not the lightness in all the extracted determination areas p1 to p9 is within a predetermined range (fixed lightness range Bc) (step S35). Here, when it is determined that the lightness in the plurality of determination regions p1 to p9 is within the fixed lightness range Bc (step S35: YES, see FIG. 25), the irradiation condition determination unit 408 uses predetermined notification means (display monitor). Etc.), a notification that the desired illuminance distribution is not obtained in the irradiation range A irradiated by the illumination device 2 is made (step S36), and the process is terminated.
On the other hand, when it is determined that the brightness does not fall within the fixed brightness distribution Bc in at least one of the plurality of determination regions p1 to p9 (step S35: NO, see FIG. 24), the irradiation condition determination unit 408 passes through the notification unit. A notification that the desired illuminance distribution is not obtained in the irradiation range A irradiated by the illumination device 2 is given (step S37), and the process returns to step S33 (image data P ′ acquisition process).

  According to such a processing flow, when the brightness does not fall within the predetermined range in any of the determination regions p1 to p9 (step S35: NO), the processing of step S33 to step S37 is repeated. During this time, the operator adjusts the irradiation conditions (light emission intensity, light projecting direction, or irradiation time) of the illumination device 2 (light emitting unit 21). Then, when the irradiation conditions are appropriately adjusted and the lightness falls within the predetermined range in all the determination regions p1 to p9 (step S35: YES), a notification that the illuminance becomes uniform is given. The process ends.

[Function and effect]
According to the license plate recognition system 100 as described above, the irradiation condition of the illumination device 2 can be adjusted based on the imaging data P ′ actually acquired by the imaging device 1. That is, it is possible to determine the optimum irradiation condition with reference to the imaging state (brightness) of the imaging target reference member 41 arranged on the road surface S, with these imagings being uniformly captured.
Thereby, the burden at the time of determining the said irradiation condition about the illuminating device 2 which can set an irradiation condition finely can be reduced significantly.

  As described above with reference to FIG. 22, when the imaging device 1 acquires the imaging data P ′, a plurality of imaging target reference members 41 are installed for each of the plurality of irradiation sections included in the irradiation range A of the illumination device 2. Has been. If it does in this way, according to the irradiation conditions of one light source part 210, the brightness of one judgment field p1-p9 corresponding to the irradiation division of the light source part 210 will change greatly. Therefore, the operator can adjust the brightness for each region (determinations p1 to p9) in which the imaging target surface is imaged in the imaging data P ′ and the irradiation condition for each light source unit 210 to correspond to some extent. Thus, the burden on the operator's adjustment work can be further reduced.

In the above description, the irradiation condition adjustment function (irradiation condition determination unit 408) in the fifth embodiment is incorporated in the license plate recognition system 100 and exhibits its function by operating in the “irradiation condition adjustment mode”. However, in other embodiments, the present invention is not limited to such an aspect. For example, the irradiation condition determination unit 408 may be provided in a device (irradiation condition determination device) different from the information collection device 4. In this case, the irradiation condition determination device acquires the imaging data P ′ for irradiation condition determination from the imaging device 1 and performs the illuminance distribution determination processing in the imaging range R.
In this case, the installation location of the irradiation condition determination device is not limited to the installation location of the information collection device 4, and is installed at a location where the operator can check the determination result in real time while adjusting the irradiation conditions, for example. It may be done.

  Further, the irradiation condition adjustment system according to the fifth embodiment performs “absolute evaluation” of lightness in each of the determination areas p1 to p9 of the imaging data P ′, that is, each lightness is within a predetermined range. It has been described that it is determined whether or not it is within the (fixed brightness range Bc). However, the irradiation condition adjustment system according to another embodiment is not limited to this mode. For example, the irradiation condition determination unit 408 according to another embodiment may perform “relative evaluation” of lightness in the determination regions p1 to p9 of the imaging data P ′.

  Specifically, the irradiation condition determination unit 408 obtains the maximum brightness Bmax and the minimum brightness Bmin among the brightnesses in the determination regions p1 to p9, and calculates the maximum brightness difference ΔB (ΔB = Bmax−Bmin). To do. When the maximum lightness difference ΔB is equal to or smaller than the predetermined determination threshold Bth (ΔB ≦ Bth), the irradiation condition determination unit 408 substantially uniformizes the lightness in the imaging data P ′, and the illumination intensity desired by the irradiation range Notification of distribution is made (step S36). On the other hand, when the maximum brightness difference ΔB exceeds the predetermined determination threshold value Bth (ΔB> Bth), the irradiation condition determination unit 408 does not equalize the brightness in the imaging data P ′, so that the irradiation range is Notification that the desired illuminance distribution is not achieved is made (step S37).

In the case of “absolute evaluation”, there may be a case where the irradiation condition of the lighting device 2 alone cannot be accurately evaluated due to the influence of sunlight, ambient lighting (such as a streetlight), or the like. Further, depending on the surrounding environment as described above, the distance between the position of the main body of the lighting device 2 and the imaging range, or the like, there is a possibility that an illuminance distribution that satisfies the determination criterion cannot be obtained. On the other hand, by using the “relative evaluation” as described above, it is determined whether or not the brightness is uniform based on the light distribution of the lighting device 2 alone, even under the influence of sunlight or ambient lighting. can do.
Note that the irradiation condition determination unit 408 may further perform the determination process by combining the above-described “absolute evaluation” and “relative evaluation”. Specifically, the irradiation condition determination unit 408 determines whether or not the lightness in each of the determination regions p1 to p9 is within the fixed lightness range Bc, and further, the maximum lightness difference ΔB within the fixed lightness range Bc. It may be determined whether or not is equal to or less than the determination threshold Bth.

  In the above description, the license plate recognition system 100 according to the fifth embodiment sets the irradiation condition for each of the illumination devices according to the first and second embodiments, that is, the light source unit 210 finely divided. Although the example which adjusts irradiation conditions was demonstrated about the illuminating device which enables, in other embodiment, it is not limited to this aspect. For example, the above-described irradiation condition adjustment system may use a conventional illumination device that cannot finely change the irradiation condition of the light emitting surface as an adjustment target. For example, when a plurality of the conventional illumination devices are installed and the imaging range of one imaging device 1 is irradiated, the imaging reference member 41 is arranged for each irradiation range A irradiated by each of the plurality of conventional illumination devices. Then, each irradiation condition of the conventional illumination device may be adjusted according to the determination result of the lightness distribution of the imaging data P ′ acquired by the imaging device 1.

  Further, in the present embodiment, the irradiation condition adjustment system includes an irradiation condition determination unit 408 that determines whether or not the brightness of the determination regions p1 to p9 in the imaging data P ′ is within a predetermined range. Although described as a thing, the aspect which does not require this irradiation condition determination part 408 may be sufficient as the irradiation condition adjustment system which concerns on other embodiment. For example, the operator may simply adjust the irradiation condition of the illumination device 2 while visually determining whether or not the brightness of the determination areas p1 to p9 included in the imaging data P ′ is uniform. Good.

  In the above description, the imaging reference member 41 is described as being arranged for each irradiation section corresponding to each of the light source units 210. However, the imaging reference member 41 is not necessarily arranged for each irradiation section. Not necessary. That is, the imaged reference member 41 functions as an index for setting the illuminance within the imaging range R of the imaging device 1 to a predetermined illuminance, even if not arranged so as to correspond to each of the light source units 210. It only has to be arranged.

  Moreover, although the above-described imaged reference member 41 has been described as being installed such that the imaged surface 41a stands perpendicular to the road surface S, the present invention is not limited to this aspect in other embodiments. For example, in consideration of a license plate of a motorcycle, the imaging surface 41a may be formed so as to face upward by about 30 ° with respect to the vertical direction of the road surface S. In addition, the imaging reference member 41 may be in any form as long as the imaging reference member 41 is imaged by the imaging device 1 and serves as a reference in determining the irradiation conditions of the illumination device 2.

  Each process of the information collection device 4 in each of the above-described embodiments is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. An aspect may be sufficient. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM (Compact Disc Read Only Memory), a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof, as long as they are included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 ... Imaging device 100 ... License plate recognition system 101 ... Vehicle 101a ... Ordinary car 101b ... Large car 101D ... Onboard equipment 102 ... Lane 2 ... Illumination device 20 ..Case 20a ... Horizontal insertion shaft 21 ... Light emitting part 210 ... Light source part 210A ... Drive mechanism 21a ... Infrared LED
21b: Mounting board 22: Setting input unit 23: Current adjusting unit 23A ... Drive mechanism control unit 24 ... Power supply unit 25 ... First axis movable unit 25a ... Horizontal insertion Port 25b ... Vertical insertion port 26 ... Second axis movable portion 26a ... Vertical insertion shaft 26b ... Joint surface 3 ... Mounting column 4 ... Information collecting device 400 ... Communication unit 401 ... Imaging data analysis unit 401a ... Position specifying unit 401b ... Imaging state determination unit 401c ... Vehicle information extraction unit 402 ... Irradiation condition setting unit 402a ... Built-in clock 403 ... Storage unit 404 ... billing processing unit 405 ... vehicle type identification unit 406 ... statistical information storage unit 407 ... mode selection unit 408 ... irradiation condition determination unit 41 ... imaged reference member 41a ... Imaging surface 41b ... support surface

Claims (9)

Provided so as to irradiate corresponding to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on the road surface, each having a light emitting unit composed of a plurality of light source units capable of independently adjusting the irradiation conditions A lighting device;
An irradiation condition setting unit configured to set the irradiation condition of the light source unit based on state information indicating a state of the road surface or a vehicle traveling on the road surface acquired corresponding to the irradiation section;
A lighting system comprising: An imaging state determination unit for determining an imaging state of a license plate imaged by an imaging device capable of imaging a predetermined imaging range on the road surface;
With
The illumination system according to claim 1, wherein the irradiation condition setting unit sets the irradiation condition based on the imaging state determined by the imaging state determination unit as the state information. A position specifying unit for specifying a position on the road surface of the license plate imaged by the imaging device;
The irradiation condition setting unit sets the irradiation condition of the light source unit corresponding to the irradiation section to which the position of the license plate specified by the position specifying unit belongs based on the imaging state. The lighting system described. The position specifying unit includes:
The lighting system according to claim 3, wherein a position at the time of the second and subsequent imaging of the license plate captured at the first time is specified based on a traveling speed of the vehicle. The said irradiation condition setting part sets the said irradiation condition based on the vehicle type which the vehicle type discrimination | determination means which can discriminate | determine the vehicle type of the vehicle which travels as said state information. The lighting system according to any one of the above. The irradiation condition setting unit
The irradiation condition is set as the state information based on statistical information indicating a vehicle type composition ratio for each time zone of a vehicle traveling on the road surface. The lighting system according to one item. The illumination system according to any one of claims 1 to 6,
An imaging device capable of imaging a predetermined imaging range on the road surface, and imaging a license plate of a vehicle traveling on the road surface;
License plate recognition system. Provided so as to irradiate corresponding to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on the road surface, each having a light emitting unit composed of a plurality of light source units capable of independently adjusting the irradiation conditions The illumination method characterized by setting the irradiation conditions of an illuminating device based on the state information which shows the state of the said road surface acquired corresponding to the said irradiation division, or the vehicle which drive | works the said road surface. Provided so as to irradiate corresponding to each of a plurality of irradiation sections obtained by dividing a predetermined irradiation range on the road surface, each having a light emitting unit composed of a plurality of light source units capable of independently adjusting the irradiation conditions A computer of a lighting system having a lighting device;
Irradiation condition setting means for setting the irradiation condition of the light source unit based on state information indicating the state of the road surface or the vehicle traveling on the road surface acquired corresponding to the irradiation section;
Program to function as.

Images