Shiva Electronics Nashik, Maharashtra

Slot Sensors also called as Fork Switches because of their forked shape, detect objects that pass between the two arms one is the Transmitter & the other is the Receiver. These sensors operate on a through beam design, they combine the transmitter & receiver into a fixed housing so alignment is never an issue. The transmitter emits pulsed light in the infrared wavelength range. The receiver detects the light beam and immediately converts a beam interruption caused by an object in the sensing zone into a switched signal. Fork Width is defined as the height between the transmitter & receiver. Depth is defined as the distance between the transmitter & receiver area and back of the opening.

A diffuse reflection sensor is used for the direct detection of objects. As with a retro-reflective sensor transmitter and receiver are incorporated into one housing. The transmitter emits light which is reflected by the object to be detected and seen by the receiver. This system does not evaluate the interruption of the light beam but the reflected light of an object. In the use of these photo sensors, it is important to bear in mind the color and the type of surface of the object. With opaque surfaces, the sensing distance is affected by the color of the object. Light colors correspond to the maximum distances and vice-a-versa. In the case of shiny objects, the effect of the surface is more important than the color. The sensing distance in the technical data is related to matte white paper. The switching function referred to light-on (NO) dark-on (NC) mode is therefore reversed. The transmitted light of this system is also pulsed. Since transmitter and receiver are integrated into one housing only one voltage supply and thus only one cable are necessary in contrast to through beam sensors. The sensitivity of a diffuse reflection sensor is very high.

In all automated processes sensors are absolutely necessary to provide the PLC with information. They supply the necessary signals on positions, limits or serve as pulse pick-ups for counting tasks or for monitoring rotational speed. Inductive & Capacitive Proximity Switches are useful in industries for non-contact operation free from any wear & tear with high switching frequencies and accuracy. They are insensitive to vibration, dust & moisture. Inductive Sensors detect all metals without contact. Capacitive Sensors detect almost all solid and liquid media such as metal, glass, wood, plastic, water, oil etc. Inductive Proximity Switches take advantage of the physical effect of the change in the quality factor in a resonant circuit caused by eddy current losses in conductive materials. This is how it works: ALC tuned circuit generates a high frequency electromagnetic field. This field is radiated from the active face of the oscillator. This reduce the oscillation amplitude. The change is converted into a switching signal. The operating principle permits detection of all metals irrespective of whether they are moving or not. Important: the high frequency field causes no measurable heat in the object nor is there any magnetic interference. The operation of the sensors is without interaction.  The distance to the active face at which an electrically conductive material causes a change of signal in the sensor is called sensing range. The sensing range of an Inductive Proximity Switch is defined by means of a target of mild steel (Fe 360). If the switch is damped by other metals, e.g. aluminium or copper, this is reduced. Using correction factors for every kind of metal the user can calculate the attainable sensing ranges.

For a retro-reflective sensor the transmitter and receiver are incorporated into one housing. By means of a reflector the transmitted light is returned to the receiver. An object in the beam path interrupts the beam and triggers a switching operation.  Features   Transparent objects such as bottles or foils can be detected better than with a through beam sensor because the light beam must pass the object twice and is thus weakened twice as much as with the through beam sensor. Since the transmitter and receiver are integrated into one housing only one voltage supply and thus only one cable are necessary. Compared to a through beam sensor, a retro-reflective sensor has an average excess gain. An object must have the size of the optics directly in front of the optics and the size of the reflector directly in front of the reflector.