“Sensors” have now become crucial to improve productivity.There is a wide variety of sensors, each has its strengths and weaknesses.
A photoelectric sensor emits a light beam (visible or infrared) from its light-emitting element. A reflective-type photoelectric sensor is used to detect the light beam reflected from the target. A thru-beam type sensor is used to measure the change in light quantity caused by the target crossing the optical axis.
The fiber-optic sensor has an optical fiber connected to a light source to allow for detection in tight spaces or where a small profile is beneficial.
A laser sensor uses a “laser” to emit light in a straight line. Its visible beam spot makes alignment and positioning very easy. Since the light beam is focused, the sensor can be installed without worries about stray light.
The laser displacement sensor built into the camera represents a new concept in laser sensors, in which the camera identifies the target object using an image, and by tracking a specified point the laser can measure the height of that point and any height
differences in relation to it.
A color sensor is a type of “photoelectric sensor” which emits light from a transmitter, and then detects the light reflected back from the detection object with a receiver. A color sensor can detect the received light intensity for red, blue and green respectively, making it possible to determine the color of the target object. There are two types of color sensors. One illuminates the object with broad wavelength light and differentiates the three types of colors in the receiver. The other type illuminates the object with the three types of light (red, blue, and green) independently. In both scenarios, the received light intensity of red, blue and green are detected, and the ratio of light received is calculated.
A proximity sensor can detect metal targets approaching the sensor, without physical contact with the target. Proximity sensors are roughly classified into the following three types according to the operating principle: the high-frequency oscillation type using electromagnetic induction, the magnetic type using a magnet, and the capacitance type using the change in capacitance.
As the name indicates, this is a sensor measuring the position of a target by directly contacting it. When the height of the spindle changes as shown in the figure on the right, the sensor internally calculates the amount of displacement. Contact displacement sensors are mainly used for detecting the height, thickness, or warpage of the target. Since measurement is possible with the sensor head being fixed, no mechanism is required to move the sensor head. This saves installation space and greatly reduces man-hours during installation.
As the name indicates, ultrasonic sensors measure distance by using ultrasonic waves.
The sensor head emits an ultrasonic wave and receives the wave reflected back from the target. Ultrasonic sensors measure the distance to the target by measuring the time between the emission and reception. An optical sensor has a transmitter and receiver, whereas an ultrasonic sensor uses a single ultrasonic element for both emission and reception. In a reflective model ultrasonic sensor, a single oscillator emits and receives
ultrasonic waves alternately. This enables miniaturization of the sensor head.
Vision sensors use images captured by a camera to determine presence, orientation, and accuracy of parts. These sensors differ from image inspection “systems” in that the camera, light, and controller are contained in a single unit, which makes the unit’s construction and operation simple. There are differences between these sensors and other general-purpose sensors. For example, many things – such as multi-point inspections – can be done with a single sensor. In addition, thanks to the wide field of view images, detection is possible even when the target position is not consistent.
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