Feature Machine Vision
characteristic of the family of Balluff BVS Vision Sensors is that they are equipped on the software side with such a vari- ety of tools for performing multiple inspection functions simultaneously or in rapid succession. A Vision Sensor can replace several standard sensors and can switch from one inspection to another. This saves hard- ware costs and constant set-up when products are changed.
Reducing cost, increasing quality A
The Balluff BVS Vision Sensor family includes a model for detecting and identifying 1D codes (barcode) and 2D codes (data matrix). The BVS-E Identification reads the commonly found codes and can verify texts and number sequences. It also reads multiple codes in one pass and works reliably under challenging conditions
The same is true of the new BVS-E Identification, which has been designed for reading and detecting barcodes and data matrix codes. In their outward appearance the new sen- sors do not differ significantly from the successful BVS-E Standard and BVS-E Advanced models. The con- struction similarity of the sensor family offers the advantage that when inspection tasks change or when dif- ferent combinations of inspection and checking are required, a uniform series of devices can be used. They are flexi- bly interchangeable and make use of the same line of accessories, from con- nection cable to mounting brackets to auxiliary lights - leading to cost saving benefits for the user.
As simple as a sensor Balluff Vision Sensors the size of a credit card are generally available with built-in processing electronics, lighting and digital outputs. Once configured they run autonomously. The results ‘Inspection OK’ or ‘Inspection NOK’ are, in the case of the BVS-E Identification, available directly on the digital outputs. If the code data which was read is required, this can be output via RS232 or through an Ethernet interface. This makes it possible to trace which parts have been processed.
The range of readable codes includes the usual suspects and includes in terms of barcodes, the pop- ular Interleaved 2-of-5, Code 39, Code 128, Pharmacode, Codabar, and EAN 8 to EAN 13 UPC-E. Using OCV even texts or number sequences can be veri- fied based on learned pixel patterns. The new BVS-E Identification shows its special ability when reading multiple codes simultaneously. This feature is often used in applications where, in addition to barcode, Data Matrix code and plain text marking are
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used. This situation used to require multiple sensors, each of which was specialised in reading only barcode or only data matrix. Since Balluff Vision Sensors can read 1D and 2D codes as well as multiple codes in a single inspection, they save repeated read cycles and eliminate the need for sev- eral sensors. Their read performance is also boosted by the 360° Locator tool. This means products and labels do not have to be exactly aligned, vastly sim- plifying system design.
BVS-E Identification sensors also handle reading of direct imprinted codes with outstanding reliability. Such markings can often represent a special challenge, for example when they are applied to cast materials or on reflective surfaces. Even in these applications the Balluff sensors oper- ate reliably. The reason lies in the algorithms used and in the fact that the sensor requires a smaller number of pixels than with traditional devices to recognise the individual symbol elements (points) in data matrix code.
Optimal light
What also optimises process reliability in certain applications is individually tailored lighting. This maximizes the contrast between good and bad fea- tures. Like all Vision Sensors from Balluff, the new BVS-E Identification is equipped with an internal incident light source (red LED). To supplement or replace the built-in light, various external lights are offered in the BVS accessory line, including red light, white light or infrared. One type often
Above and below: Balluff’s new Vision Sensors provide high quality code detection
used in code reading is the ring light. This is used as an auxiliary incident light source, or to replace the inte- grated light when the application requires an infrared or white light. With their high brightness LEDs, ring lights provide virtually shadow- free, high intensity illumination. They are especially useful when the dis- tance between the BVS and the target code is greater than 300mm. Thanks to their brightness they also suppress the effects of varying ambient light. The right light and Vision Sensor are attached and aligned using the spe- cially designed Balluff Mounting System. Other optional light types include line, spot and dark field designs. Background illumination, helpful for situations where transmit- ted light is used, is used in special applications for code reading. Integrating BVS-E Identification in automation applications, regardless of whether existing or new equip- ment, is simple. Operation and start- up are handled using the free, ConVis software, used with all BVS-E models. The first step is to connect the Vision Sensor to a PC through an Ethernet port. The integrated soft- ware assistant then guides the user through successful configuration. Brightness and the lighting setting, as well as the desired inspection fea- tures, are determined using a teach- ing procedure. Then the output signals are configured. Using the ‘tool’ for code detection, barcodes or data matrix codes within the field of view are quickly read. In the last step the code reading is checked on the screen. Here adjustments or correc- tions can be made.
The BVS-E Identification extends the versatility of vision sensors to code detection and identification. Using the mature technology even the most chal- lenging conditions can be handled economically and reliably. Users of EPLAN CAD and CAE software can download the macros for the BVS Vision Sensors from the Balluff web- site and use drag-and-drop for 1D and 2D code detection, reducing costs and increasing quality.
Balluff
www.balluff.co.uk T: 0161 282 4726
Enter 232 OCTOBER 2013 Machine Vision
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