Projects Inspection & Verification Of LED Panel Displays
BACKGROUND
Hanover Displays designs and manufactures passenger information systems for the public transport industry.
Satisfied customers in over 75 countries worldwide use a range of Hanover products, attracted by high levels of quality, reliability and customer service. Two fully equipped production facilities in the United Kingdom and the United States enable Hanover to produce more than 45,000 units annually across the product range. These are shipped to customers in over 75 countries throughout the world on a client list that includes transport authorities, fleet operators, and vehicle manufacturers.
Destination display on bus
Building display panels
SOLUTION
Hanover Displays worked with Scorpion Vision to develop a machine vision-based process for 100% panel inspection, capable of identifying any LEDs that do not illuminate as well as checking the colour and intensity of illumination of those that do. This was part of a co-ordinated approach to increase levels of automation during the testing phase which now also includes the use of COBOTs (Collaborative Robots) in some areas.
A phased development program for the vision system featured the design and development of a prototype which was evaluated and improved over a period of several months before construction of the final production systems. The vision solution consists of a self-contained inspection station housing a high resolution area scan camera with a matched 2/3" 5mm F1.8 Manual Iris C-Mount Lens for the board inspection, an embedded industrial PC and a specially designed fixture onto which the panels are loaded for inspection. A hand-held bar code scanner and touch screen display are positioned by the side of the inspection station. The high-resolution camera ensures that very small LEDs (2mm and 3mm pitch) on densely populated panels can be imaged.
The system is also integrated with Hanover’s test system which carries out electrical and thermal tests. The inspection process starts by loading the panel into the fixture and using the hand held scanner to read a QR code located near the edge of the panel. The QR code data include information on the specific panel type, allowing the vision system to automatically load the necessary inspection parameters. These include the number of rows and columns on the panel, LED size and intensity threshold and deviation in the X and Y axes which can be used to detect the exact LED(s) turning on during test. The test then begins automatically, running five illumination sequences, where firstly odd columns are illuminated, then even columns are illuminated, followed by odd rows, even rows and finally all LEDs are illuminated simultaneously.
Inspection system
Results display screen
In the event of a failure, the image of the failed panel is also saved, overlaid with markers to clearly show the location of any failed LEDs. A simple panel training process was also included in the design to allow the system to be quickly trained to produce product profile files for any new products.
Image of failed LED panel
GET IN TOUCH
We are always delighted to hear from our customers. If you’d like to ask a question, make an enquiry or request support, please contact us through one of the methods below or by using the enquiry form.
Telephone: +44 (0) 1590 679333
Sales: [email protected]
Technical: [email protected]