Apr. 01, 2009

Smart Cameras of the Next Generation

Innovation Focus on User Needs

  • On lot changes, the new check routine is loaded with the focus setting for the specific camera distance. On lot changes, the new check routine is loaded with the focus setting for the specific camera distance.
  • On lot changes, the new check routine is loaded with the focus setting for the specific camera distance.
  •  By means of the motor-driven focus adjustment, the device moves to the appropriate focus position, i.e. no manual focusing is necessary on the device.
  • Compared with conventional LED illumination, the image acquired by the LSIS 400i series is considerably more homogenous and more detailed.
  • The parameterization software does not need to be installed on the user‘s PC. It is ‚on board‘, and can be accessed with any web browser.
  • With the high-performance blob analysis of the LSIS 410i, a wide range of tasks in completeness and presence inspections as well as in position detection can be performed easily and reliably

Optical sensors specialist Leuze electronic has been active in the area of machine vision for over a decade. Based on the know-how acquired over this time and in numerous applications, a new high-performance series of smart cameras characterized by unique features such as web configuration, motor-driven focus adjustment, homogeneous light design and a particularly powerful blob analysis was now developed. These features simplify integration for the user, offer flexibility in the application and enable a wide usage spectrum as well as high process reliability.

In recent years various device classes, differing in flexibility and subsequent cost of integration, have established themselves for applications in machine vision, a key technology within the automation sector. PC- or controller-based vision systems are at the peak of the performance spectrum. For the majority of automation tasks, however, vision sensors - or the more-powerful, faster and flexible smart cameras - are the better choice. They can be integrated quickly and at lower cost, yet offer flexibility and performance that is sufficient for many applications. In this market segment, the new LSIS 400i series developed by Leuze electronic represents the smart camera of the next generation.

In the User's Focus
The user of machine vision knows that the focus of a vision application is not only on the processing performance or the embedded algorithms, but that the decisive factors for the success of the implementation encompass illumination, flexibility in camera adjustment and costs associated with integration. This includes mounting and alignment options as well as easy operation.
As a performance-determining element the illumination is among the most important qualitative features of such systems. Here very often LEDs are used which are normally arranged in a ring shape, whereby each individual LED emits its light at a specific angle. The light pattern is naturally round in shape: characteristically dark on the inside with an intensity that, at first, increases strongly to the outside and then again decreases with increasing distance from the center. Furthermore, the round light spot stands in contrast to the rectangular camera chip.

The inevitable result of such an arrangement is a relatively inhomogeneous illumination which, in the end, affects the quality of the image analysis.
At least just as relevant to quality for a vision system and the achievable gauging and inspection results is focusing. A wide range of solutions is available here, ranging from interchangeable to adjustable objectives. Most of these require manual access in applications that are often located in constrained spaces. As a result, exact focusing is associated with difficult alignment and is often difficult to reproduce.
Not obviously relevant to quality, yet always in the user‘s focus, is the handling of the smart camera. This involves, above all, the configuration, which generally is executed via a dedicated software program installed on a PC. And which service technician and which maintenance engineer has not yet had the painful experience that exactly this PC is not accessible when urgently needed.

Full of Innovations
Leuze electronic has taken these as well as many other requirements into account and incorporated them in the development of the new LSIS 400i smart camera series. This new series is full of high-performing innovations. The fact that the ­development incorporated extensive application know-how is apparent even externally in the industrial-suited appearance with a robust metal housing. A glass window, sealed airtight in accordance with protection class IP 65, protects the camera technology and the illumination system integrated behind the glass. Instead of using standard LEDs, Leuze developed an illumination system with special optics. It consists of eight rectangular segments fitted with precisely calculated, free-form shapes. As a result, each of the segments generates an extremely homogeneous, rectangular light pattern that is particularly intense in the range from 50 - 250 mm.
Not noticeable at first glance, but of decisive importance for the flexibility and, thus, attainable quality, is the motor-driven focus adjustment. On lot changes with different object distances, this saves the user the need to perform manual focusing. The new check routine is loaded with the focus setting for the specific camera distance. The motor-driven focus adjustment moves the lens to the corresponding focus position. An innovation that facilitates reproducible adjustments as well as improvements in quality and, particularly in applications with restricted installation space, one that results in a noticeable simplification.
Another new feature, and one that considerably eases use of the smart camera, is the integrated webConfig configuration interface. Developed by Leuze and first used in the BCL 500i barcode readers as configuration software, this program enables device configuration directly via a web browser. With the LSIS 400i, however, performance goes greatly beyond that of a configuration tool. Here, the entire image processing software is integrated in the device. An Ethernet interface provides fast and easy access to the device for simple integration. The software does not need to be installed on the user‘s PC. It is ‚on board‘, and can be accessed with any web browser. Should servicing be necessary, this means that the complete configuration software as well as an online help system, are avail­able on-site within the device - at all times and wherever it may be located.

Software Competence
A key factor for the performance of the new LSIS 400i series is the blob analysis implemented by Leuze electronic. Blob stands for binary large object and is a common and well-proven method of image processing. It identifies a continuous area of pixels in an image. By making use of blob features, such as area and circumference, individual objects or object groups can be specifically detected. An area is the summation of the pixels enclosed in a blob, optionally including any holes within the blob. The circumference is the length in pixels of the outer contour of a blob. The new LSIS 400i can check for considerably more properties, however. For example, the ratio between area and circumference of a blob can be used to determine a shape factor that classifies its geometric appearance. Furthermore, by checking the major and minor axes of a blob, the rota­tional position of an object can be determined. With the high-performance blob analysis, this new generation of smart cameras can simply and reliably perform a wide range of tasks in completeness and presence inspections as well as in position detection.

Innovations such as the illumination system developed by Leuze electronic or motor-driven focus adjustment, satisfy the highest demands in reliability, efficiency and flexibility. With its integrated webConfig configuration interface, Leuze electronic demonstrates user-oriented development know-how that considerably simplifies device integration and operation. Also worth mentioning in this context is the bilingual display on the device for simple diagnostics and status displays, the integrated connectivity with Ethernet and RS 232 interfaces - with eight digital, configurable inputs and outputs - and the intelligent fastening concept with M12 connection technology.


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