ANPR Systems

ANPR systems combine lighting and cameras to capture the number or license plate details on vehicles through optical character recognition (OCR). The system software identifies the characters which are then compared to a database. Any existing information attached to the registration number is then flagged.

ANPR Systems Applications

ANPR systems were initially developed in the late 1970’s for stolen vehicle detection but their use is now common in a wide array of law enforcement applications across the globe. In addition, other types of applications have developed as the technology has matured including the use of ANPR systems in parking, road tolling and journey time measurement applications.

Some of the earliest major installations of ANPR systems occurred with the introduction of the “Congestion Charge” zone in London and the installation of the “Ring of Steel” in the City of London. Countries around the world have rapidly adopted this technology and new applications continue to be identified.

Considerations for LED Lights for ANPR

Illumination is critical in ANPR applications as inadequate lighting will result in reduced accuracy and reliability of the overall system. Key considerations in developing the optimum illumination include wavelength, form factor, intensity and lifetime.

Wavelength

Generally, IR illumination is used in ANPR applications as it is invisible to the human eye, preventing distraction of drivers and also creates high quality images from the retro-reflective coatings on the plates. A recent development to expand the capability of ANPR systems, enabling high definition color recognition, is the incorporation of multiple carefully selected wavelengths.

Form Factor

In mobile and covert applications, the size or form factor of illumination is critical. A compact solution allows the light to be positioned closer to the camera which reduces the overall size of the system and also provides an improved angle of illumination.

Robustness and Reliability

ANPR lights must be robust and rugged. The systems are typically used outdoors and therefore can be exposed to extreme weather conditions. A robust system is required to ensure repeatable, reliable results.

ANPR systems typically operate at a significant working distance from the target requiring a high level of intensity to provide adequate illumination. In many applications, ANPR systems are used at heights where replacement of illumination would be difficult and hazardous. The long lifetime provided by LED lights are ideally suited to these applications.

ANPR Lights from ProPhotonix

ProPhotonix has a wealth of experience in developing LED lights for ANPR applications. Our products have been integrated in systems installed globally. Our 15 years of experience is testament to the reliability of our products and our ability to innovate as new trends develop. During these 15 years, we have continued to support our market-leading customers as they have developed more advanced systems, improving system capabilities and developing new applications.

For more information visit the our ANPR page or download the case study.

The post LED Lights for ANPR Applications: Infrared Illumination appeared first on Prophotonix.

A leading US and UK-based manufacturer of Automatic License/Number Plate Recognition (ANPR) systems approached ProPhotonix requiring an illuminator for integration into fixed & mobile ANPR systems. The requirement was for a compact, high intensity, strobable IR light source in a range of wavelengths for use in different geographic regions.

There were a number of challenges for providing the solution for this application:

The Correct IR Wavelengths

Number plates are often made with retro-reflective materials designed to reflect IR radiation. Infrared light is also ideal for this application as it is invisible to the human eye and won’t distract drivers. License plates differ from one geographic region to another and for this reason the customer wanted the product in several different wavelengths. 870 nanometer (nm) is the most suitable wavelength for ANPR systems in Europe. However, in the United States, where license plate regulations vary by region, alternative IR wavelengths e.g. 940 nm, are sometimes found to be more suitable for use. ProPhotonix developed solutions to provide output wavelengths of 810nm, 870nm and 940nm.

Delivering enough intensity for a 25m range

To achieve established accuracy and reliability standards, the customer required illumination components to provide adequate illumination over a 15-25 meter (m) working range. To maximize source intensity, ProPhotonix designed a Chip-on-Board (COB) array consisting of tightly spaced, high-intensity LEDs and beam shaping.

Enabling a Compact IR Illuminator

An additional requirement was for an illuminator for both mobile and stationary ANPR systems. The customer required a compact form factor, confined by the small size of the system. In addition, as IR light is retro-reflected by target number plates, the gain factor of the system camera is maximized by aligning the camera and IR source as closely as possible, further restricting the mechanical design of the solution.

Strobe Capability

ALPR/ANPR systems send a signal to the illumination source to provide a series of IR strobe pulses which synchronize with the image capture by the system camera. Typically, to accommodate a variety of environmental conditions, both the duration and intensity of the IR pulse is varied by the ANPR system. Strobe capability was a key requirement of the project.

The Solution

ProPhotonix considered all of the customer requirements in the development of a range of customized SpecBright Spotlights. The SpecBright has been successfully incorporated into the camera systems, which are currently utilized in a large number of applications in the security sector. For more information, download the case study.

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