The SMARTEYE® MARK II sensor is one of TRI-TRONICS’ most popular photoelectric sensors. The SMARTEYE® MARK II features extremely high gain combined with very high speed. These high performance sensors were designed to resolve the most difficult sensing tasks...the hallmark of all TRI-TRONICS SMARTEYE® sensors. In addition to superior high gain/high speed, the SMARTEYE® MARK II is equipped with many new improvements. Among the many features included in the design of the SMARTEYE® MARK II , none is more important than the EDR® circuit. Now, thanks to the addition of EDR® (Enhanced Dynamic Range), the dynamic operating range has been extended and background suppression has been enhanced. Also included in the design of the new SMARTEYE® MARK II are all of the proven features included in all SMARTEYE® sensors, including our unique Contrast Indicator.
Without question, the SMARTEYE® MARK II sets a “new standard of performance” in photoelectric sensing. When the sensing task involves resolving critical identifying features such as size, texture, distance, opacity, depth, or color, the SMARTEYE® MARK II will give you that extra measure of performance that is often required to ensure proper operation. Marginal performance cannot be tolerated when the entire operation of an automated machine process relies on the ability of a photoelectric sensor to perform its sensing task.
The EDR® circuit extends the dynamic operating range to provide unequaled performance at very bright light levels.
Every photoelectric sensor has a saturation point – a point at which any further increase in received light level to its detector (from its own pulsing LED light source) will not result in any further internal signal level increase. This is apparent on the SMARTEYE’s Contrast Indicator. For example, in an object sensing task, if the background (i.e., white conveyor belt) is reflecting enough light back to the sensor’s detector to reach the sensor’s saturation level, the arrival of an object (such as a cookie) will not result in any signal level increase as displayed on the Contrast Indicator. This undesirable condition is referred to as saturation.
To avoid saturation and enhance background suppression, the EDR® circuit monitors the offset adjustment during setup to determine when the sensor’s operating level is approaching the sensor’s light level saturation point. Before saturation occurs, the EDR® circuit adjusts the sensor in such a unique manner so as to prevent saturation and extends the overall dynamic range of the SMARTEYE® MARK II sensor.
Proximity Sensing Mode Advantages
Another performance benefit provided by the EDR® circuit when operating in the proximity mode is that the SMARTEYE® MARK II does not typically require the use of convergent or triangulating optics to resolve objects resting on shiny or highly reflective backgrounds. Instead, the optics can be divergent, allowing a wider field of view. The larger the area in view of the sensor’s optics, the greater the contrast deviation. Convergent or triangulating optics results in pinpoint spots of light. These optical sensing methods can result in falsely switching the sensor’s output by responding to minute surface variations or imperfections. A wider field of view offered by divergent optics (i.e., wide angle proximity lens or large bundle fiberoptic guides) allows the SMARTEYE® MARK II to overlook most minor surface irregularities.
Beam Break Sensing Mode Advantages
When operating in the Beam Break (opposed) mode of sensing, the EDR® circuit once again prevents saturation. This is particularly advantageous when attempting to detect the presence of splices, overlapping materials, container contents, or adhesive labels on backing materials. Saturation can easily occur particularly when the materials involved are translucent or transparent. Example: In label detection, if the intensity of light penetrating through the label has reached the saturation level of the sensor, the arrival of the gap between labels will not increase the signal level as displayed on the Contrast Indicator. If this is allowed to occur, detection of the label is impossible. The new EDR® circuit built into the SMARTEYE® MARK II prevents this from occurring by compensating during the setup procedure to prevent saturation.