Page 1 Photoelectric sensors ifm electronic Sensors, networking and control technology for automation Training manual Photoelectric sensors Training manual...
Page 2 Photoelectric sensors For further information, data sheets, prices, etc. please go to www.ifm-electronic.com Training manual photoelectric sensors (as in March 2003) \\DEESNW01\VE\VTD\DATEN\STV\INTERN\Sc- und Se-Unterlagen alt\ENGLISCH\SC\SC200\Sc200e.doc 22.02.05 17:09 Note on guarantee Utmost care was taken when writing this manual. Nevertheless, we cannot guarantee that the contents are correct. Since it is impossible to avoid mistakes despite intensive efforts, we always appreciate indications.
Page 3: Table Of Contents
Photoelectric sensors Contents Introduction 1.1 Photoelectric sensors in industrial applications 1.2 Notation 1.3 On the contents Light 2.1 Electromagnetic waves 2.1.1 Nature of the light 2.1.2 Ranges of wave length 2.1.3 Origin of light 2.1.4 Radiation spectrum 2.2 Radiation and temperature 2.2.1 Black emitters 2.2.2 Emission 2.2.3 Reflection and colour...
Page 4 Photoelectric sensors 3.3.2.3 Prismatic reflector 3.3.2.4 Summary 3.4 Diffuse reflection sensors 3.4.1 Operating principle 3.4.2 Notes on the use of diffuse reflection sensors in practice 3.4.2.1 Range 3.4.2.2 Setting 3.4.2.3 Background suppression 3.4.2.4 Summary 3.4.3 Units with special features 3.5 Fibre optics 3.5.1 Typical applications 3.5.2 Operating principle 3.5.3 Notes on the use of fibre optics in practice...
Page 5 Photoelectric sensors 4.6 Units with special properties 4.6.1 Side or front lens 4.6.2 Separate amplifier 4.6.3 Contrast sensor 4.6.4 Colour sensor Infrared sensors 5.1 Operating principle 5.1.1 Radiation 5.1.2 Degree of emission 5.1.3 Technology 5.2 Information on practical use 5.2.1 Angle of aperture 5.2.2 Setting instructions for OWI 5.2.3 Operating conditions Applications...
Page 6: Introduction
Photoelectric sensors Introduction Photoelectric sensors in industrial applications What are they used for? Photoelectric sensors have become indispensable components in almost all automated production processes. Photoelectric sensors are used for safe and fast detection, positioning and counting of parts. We would like to start with one example of the variety of applications. Other applications can be found below (see e.g.
Page 7 Photoelectric sensors Examples Type Accessories Market segment packing industry fibre optics packing industry and automation angle brackets packing industry; food industry angle brackets with materials handling protective cover mounting components food industry Modern photoelectric sensors offer a precise lens and intelligent electronics as a standard.
Page 8: Notation
Photoelectric sensors Notation The notation is explained here to make it easier to read the text and to find information. Headwords Headwords are indicated at the left margin. They give information on the topic in the following paragraph. What does FAQ mean? It means Frequently Asked Questions.
Page 9 Photoelectric sensors Annex This manual is also meant for your own studies. Terms that are less frequently used are explained in a short technical glossary. The points that are essential for the photoelectric sensor are explained in details in the preceding chapters. The index helps to look up a topic. The glossary contains another short explanation of important terms.
Page 10: Light
Photoelectric sensors Light Is it necessary to know this? In this chapter the physical principles are described briefly. If you know this or remember what you have once learnt about it, the understanding of the operating principle and the overview of the sensor types and their use is easier.
Page 11 Photoelectric sensors Danger ! To understand the danger of radiation for human beings the following two aspects have to be taken into account. There may be two different types of danger. • Intensity If you focus for example the light of the sun in a burning glass, contact with the skin can result in burns.
Page 12: Ranges Of Wave Length
Photoelectric sensors can be imagined as a straight line. The statement "vertical to the direction of propagation" is thus ambiguous. There are two possibilities, e.g. "upwards" or "to the side". Polarisation Normally light has no preferred direction of oscillation. If the direction is however limited to one single direction by a filter, this is called polarised light.
Page 13 Photoelectric sensors Figure 3: electromagnetic radiation spectrum The upper part of Figure 3 shows the range that is of interest here. The following table defines the range in more details. Wave length range Radiation designation 100 nm - 280 nm UV - C 280 nm - 315 nm UV - B...
Page 14 Photoelectric sensors without any problems at all (diffraction . This is why radiation at very long wave lengths (IR and not UV) is used to provide protection against soiling and dust, see Figure 4 and Figure 5. • The units are less susceptible to extraneous light sources of the visible range by the use of infrared light.
Page 15: Origin Of Light
Photoelectric sensors Most objects which are normally used are much bigger than the wave length so that the principles of geometrical optics can be applied. But for fine dust or mist a longer wave length is advantageous to reduce failures caused by dust.
Page 16 Photoelectric sensors characterised by waves. Depending on the context light can also be imagined as particles. The energy (e.g. by heating) can only be absorbed in defined amounts. More precisely, the energy quantum is absorbed by the electron sheath. According to the Bohr atom model (Figure 6), the electrons cannot move along random paths since the distance between the electron and the nucleus depends on the energy.
Page 17 Photoelectric sensors Emission This state is not stable. Sooner or later the electron "falls" down to its basic level and emits its energy in form of radiation (Figure 8). Figure 8: radiation It cannot be foreseen when this will happen, sometimes sooner, sometimes later.
Page 18: Radiation Spectrum
Photoelectric sensors Figure 10: incoherent waves What is the direction of the beam? The direction of the beam is not defined either. Normally light is radiated evenly in all directions or is non-directional. The radiation, the light quantum, has a defined energy and thus a defined wave length.
Page 19 Photoelectric sensors Figure 11: spectrum of solar radiation GaAsP GaAlAsP GaAs Figure 12: Spectrum of LEDs Figure 12 shows that the light of the LEDs is emitted in a very small wave length range, it is almost monochrome. Curve 4 is in the red range of the visible light, 5 and 6 are infrared.
Page 20 Photoelectric sensors Figure 13: spectrum of the laser diode made of InGaAlP The spectrum of the laser diode is almost a line at 675 nm. This light is completely monochrome. This is explained below (2.3). The laser diode used in the current units consists of InGaAlP. For a better overview the spectres were shown separately.
Page 21: Radiation And Temperature
Photoelectric sensors 880 nm. Another favourable coincidence is that especially in this range the solar radiation, curve 1, is less intensive. In the complete infrared range it is less intensive than in the visible range. Most artificial light sources such as bulbs or fluorescent tubes have similar characteristics. This confirms that interference by extraneous light can be reduced by the selection of these sensor components.
Page 22: Reflection And Colour
Photoelectric sensors What is the correlation? In this paragraph the correlation between temperature and measured signal is described briefly. The two influencing factors are as follows: • differences compared to the black emitter Not all materials have a curve along the complete wave length range like the black emitter.
Page 23 Photoelectric sensors Colour filter Most materials have an effect similar to a colour filter. If light strikes for example sensors of a well-known manufacturer, most wave lengths are absorbed. Only wave lengths in the orange range are reflected. We say that the object is orange.
Page 24: Laser
Photoelectric sensors In principle three colours are enough, instead of the example of red, yellow, blue the colours orange, green, violet could have been taken as basic colours. There are high-quality printers with 6 colours. A better printing quality is reached because the ratio of mixture cannot be reproduced with the required precision if only three colours are used.
Page 25: Features
Photoelectric sensors And this is different for the laser? Correct! To understand the special features of the laser, it is important to understand what "normal" radiation is first. 2.3.2 Features Snowball effect First of all it should be described what stimulated radiation is. You can imagine two atoms.
Page 26 Eyelid closing reflex Laser sensors of ifm electronic are classified in laser protection class II. This is for example also the class of the laser pointer. The laser power, even in the setting mode, is max. 1mW. In this class it is assumed that the eyelid closing reflex is sufficient to protect the eye.
Page 27: Terms
Photoelectric sensors 2.3.3 Terms Some terms that are often mentioned with regard to lasers will be explained briefly in this chapter. Where is the pump? Such a term is "pumping". The meaning of the term is as follows. If the laser material, gases or solids, is excited e.g.
Page 28: Laser Sensors
Photoelectric sensors 2.3.4 Laser sensors Precision For the reasons given in 2.3.2 laser units are especially suited for applications that require high precision. We cannot imagine e.g. geodesy without laser units. For the use of binary sensors this high precision can however be disadvantageous if such high precision is not necessary.
Page 29: Refraction
Photoelectric sensors Refraction Why do I have to know this? This phenomenon is important for the understanding of the operating principle of fibre optics (see 3.5). Figure 17: refraction transparent -> more opaque Rays of light which pass from a transparent medium into another more opaque medium are refracted, i.e.
Page 30 Photoelectric sensors Refraction index The material characteristic "refraction index" is the ratio of light velocity in vacuum and light velocity in the medium. It is always higher than 1. Shortest time One might ask why the light path is no longer straight in this case? It is an interesting law of nature that light moves in a way that it goes from point A to point B at the shortest possible time.
Page 31 Photoelectric sensors the start. This is also the case if the fibre is bent. The bending must however not be too strong, among others because the fibre may break (see 3.5). Light Core glass Sheathing Figure 19: Total reflection in fibre Attenuation The total reflection is almost without any losses.
Page 32: Characteristics Of Photoelectric Sensors
Photoelectric sensors Characteristics of photoelectric sensors At the beginning of this chapter the photoelectric principle of the detection of objects is compared with other principles. Then the three individual sensor systems as well their special features with additional information on applications etc. are described. Comparison with other types of sensors 3.1.1 Definition What does photoelectric actually mean?
Page 33: Immunity To Interference Of Different Sensor Types
Photoelectric sensors 3.1.2 Immunity to interference of different sensor types Sensor Tempe- Moisture Dust Light Noise el.-magn. rature infrared fields (HF) inductive capacitive photoelectric (diffuse) ultrasonic high mean Figure 20: Influence of interfering factors on different sensor types The table shows the advantages and disadvantages of the sensing principles listed.
Page 34: Through-Beam Sensors
It is the intention to eliminate all possible sources of interference, such as moisture and extraneous light, and this is why photoelectric sensors, the photoelectric sensor, called here "efector 200", represents a very good system for the safe detection of objects.
Page 35 Photoelectric sensors Figure 22: through-beam sensor principle This principle of the through-beam sensor is one method of detecting objects which is used for the units. Transmitter (S) and receiver (E) The two components are briefly designated with S for transmitter and E for receiver (also in the type key).
Page 36 Photoelectric sensors 0.04° and ± 5° depending on the design). Laser units have the smallest angle of aperture. There is no clear limit between the area illuminated by the transmitter and the dark area. The highest intensity can be found in the centre.
Page 37 Photoelectric sensors α Angle of aperture (receiver or transmitter Misalignement of the geometrical axis (receiver) Working sensing range α = α + α Maximal permissible angular misalignement I = RW x tan E Maximal permissible lateral misalignement Figure 24: arrangement of transmitter and receiver arrangement of transmitter and receiver Size and duration The objects to be detected must have at least the size of the active zone...
Page 38: Information On The Use Of Through-Beam Sensors In Practice
Photoelectric sensors The values for the smallest detectable object, for the maximum diameter of the light spot etc. depend on the type and are given in the data sheets. An example is given in 2.3.4. 3.2.2 Information on the use of through-beam sensors in practice Mutual interference of several through-beam sensors When two or more of these through-beam sensors are to be mounted...
Page 39 Photoelectric sensors Figure 26: mutual interference of through-beam sensors Figure 27: alternate mounting of transmitter and receiver Also, caps or screens between the beam sensor pairs avoid interference. When using caps note that too long a cap reduces the range (excess gain)(see Figure 32).
Page 40 Photoelectric sensors Figure 29: screens for through-beam sensor 1 Interference by extraneous light To exclude interference which may be caused by extraneous light during mounting already, the units should be mounted in a way that extraneous light is prevented from directly striking the receiver lens. Figure 30: interference by extraneous light What can be done? This can for example be prevented by transversely arranging the optical...
Page 41 Photoelectric sensors Figure 32: cap on receiver Another less adequate solution is to reduce the receiver sensitivity. But this also reduces the sensing range of the system and thus the excess gain. Reflections in the environment Other problems may arise from a reflective surface. Figure 33: reflective surface What can be done? Possible solutions are:...
Page 42 Photoelectric sensors Figure 34: spacers Figure 35: screens for through-beam sensor 2 Characteristics of the through-beam sensors The following overview summarises the main characteristics. • long range because the light covers only one direct way from the transmitter to the receiver. •...
Page 43: The Retro-Reflective Sensor
Photoelectric sensors The retro-reflective sensor 3.3.1 Operating principle Another method for an optical detection of objects is the so-called retro- reflective sensor. The principle is similar to the through-beam sensor but transmitter and receiver are incorporated into one single housing. The transmitted beam is reflected by means of a reflector so that it strikes the receiver.
Page 44 Photoelectric sensors Figure 37: reflector for retro-reflective sensor 15° Simple mounting is possible since the prismatic reflector can be installed up to 15 degrees transversely to the transmitted beam without big reflection losses. A prismatic reflector consists of many small prisms, i.e. triples, which you can imagine as the cut-off edges of a cube (rectangular prisms).
Page 45 Photoelectric sensors You can also see that it is difficult to show the reflection in three dimensions. To understand the functioning of a prismatic reflector, the two-dimensional drawing of Figure 38 is sufficient. Figure 39: structure of a prismatic reflector Prismatic reflectors and laser units Here the special characteristics of the laser have to be taken into consideration.
Page 46 Photoelectric sensors Transmitter (light source) Receiver (photocell) Figure 41: light beam when a reflective foil is used Nowadays reflective foils with better reflective quality are available. For these foils triples are used instead of glass beads. The characteristics of the prismatic reflector are given in Figure 42 below. Reflection from prismatic reflector Reflection from white paper α...
Page 47 Photoelectric sensors As in Figure 23 for the through-beam sensor the following Figure 43 shows the characteristics of the retro-reflective sensor. Prismatic reflektor Sensing area = active zone Useful area = receiver characteristics α Angle of aperture Figure 43: receiver characteristics of a retro-reflective sensor The size of the active zone of retro-reflective sensors changes along the optical axis.
Page 48: Use Of Retro-Reflective Sensors In Practice
Photoelectric sensors Please note that the sensitivity of the receiver of through-beam sensors or retro-reflective sensors should always be set to maximum in order to guarantee maximum operational reliability. Reflective objects may not be sensed. • 3.3.2 Use of retro-reflective sensors in practice 3.3.2.1 Sensors with polarisation filter How can reflective objects be detected? There are two possibilities...
Page 49 Photoelectric sensors tins, glasses, mirrors), the direction of polarisation of the reflected light does not change. This light is reflected in the direction of the receiver. A second polarisation filter (analyser) is incorporated into the housing in front of the receiver with a filter which is aligned vertically to the first filter.
Page 50: Laser Units And Prismatic Reflectors
Photoelectric sensors polarisation. In order to achieve the highest range or excess gain, the foil must always be aligned vertically to the lens, that is in accordance with the alignment of the polarisation filter. Most of the units with polarisation filter are equipped with a red light diode since the polarisation filters used guarantee good functioning only in the range of visible radiation.
Page 51: Prismatic Reflector
Photoelectric sensors Overview ranges In the annex on page 160 you will find a table with range values for the different types of sensors on the different reflectors. Summary Reflector at a small distance special reflector (“laser reflector”) Reflector at a greater distance standard reflector “Small”...
Page 52 Photoelectric sensors Autocollimation The types OCP, OCPG, OCPL, OJP and OJPL are not affected by the problem posed by the dead zone. These units operate to the so-called principle of autocollimation. Here the transmitters and receivers “see” through a lens. The transmitter and receiver beam are only separated in the unit by a semipermeable reflector.
Page 53: Summary
Photoelectric sensors Counting bottles This application is critical because the light beam is only slightly attenuated if it penetrates the surface of a transparent object made of glass or plastic (foil) vertically. Unexpected effects can also result at the edges of the object. A unit with special features, the OCPG, has been especially designed for this particular application.
Page 54: Diffuse Reflection Sensors
Photoelectric sensors Diffuse reflection sensors 3.4.1 Operating principle The diffuse reflection sensor is another photoelectric sensor for the detection of objects. The basic sensing principle corresponds to a retro- reflective sensor. Transmitter and receiver are also incorporated into one single unit. Figure 49: operating principle diffuse reflection sensor Similar to the retro-reflective sensor the diffuse reflection sensor evaluates the reflected light.
Page 55 Photoelectric sensors reflective quality, that is the surface characteristics and the colour of the object (e.g. smooth, reflective, white, grey, black). • Since the reflective quality of the objects is in general lower than that of the prismatic reflector for example (see Figure 42), the maximum possible range for sensing objects is shorter than for through-beam or retro sensors (active zone).
Page 56: Notes On The Use Of Diffuse Reflection Sensors In Practice
Photoelectric sensors Figure 51: switch-on curve 3.4.2 Notes on the use of diffuse reflection sensors in practice 3.4.2.1 Range What does "range" mean in practice? The range given in the data sheets refers to a reference material. No exact values for materials with other characteristics can be calculated on this basis.
Page 57 Photoelectric sensors Figure 52: range and surface Colour In general light colours have a better reflective quality than dark colours. Paragraph 2.2.3 explained that the colour of an object results from the fact that certain ranges of wave lengths have better reflective quality than others.
Page 58: Setting
Photoelectric sensors Surface characteristics It is not so easy to enter the correlation between the range and the surface characteristics in a graph. A thumb rule is: smooth surfaces have better reflective quality than rough surfaces. In practice both influences can occur at the same time. It is obvious that a polished metal surface has better reflective quality than black velvet for example.
Page 59 Photoelectric sensors Setting in practice There are two types of setting: • manual • automatic Manual This type of setting is used for sensors with potentiometer. Proceed as follows: 1. Place the object within the normal sensing range. 2. Increase the sensitivity with the potentiometer until the diffuse- type sensor senses the object (output switches) and remember the position.
Page 60: Background Suppression
Photoelectric sensors As a consequence almost all units of the new generation only have buttons and no potentiometers. Prerequisite is the use of microprocessors in the unit. In this case buttons enable easier and better setting as well as more reliable sealing which leads to a better operational reliability. We have now completed describing the optimum setting.
Page 61 Photoelectric sensors Short-range diffuse reflection sensor and diffuse reflection sensor with background suppression What is the difference? The operating principle is similar. The short-range diffuse reflection sensor that is described first is simpler and has fewer features. The diffuse reflection sensor with background suppression enables a better adaptation to different conditions.
Page 62 Photoelectric sensors In the case of the retro-reflective sensor the dead zone only has to be taken into account for the distance of the reflector (see 3.3.2.3). The position of the object or whether it interrupts the transmitted or received light is of no importance.
Page 63 Photoelectric sensors Triangulation principle This triangulation principle evaluates the reflection of the remote light and the close light by means of two receivers, thus also obtaining a background suppression. this principle is used for the units OCH, OAH and OTH. The angle between the receivers can be changed by means of an adjustable mechanism.
Page 64: Summary
Photoelectric sensors Diode array In the meantime it has been found out that even better results can be achieved using an array of receiver diodes. It can be deduced from Figure 56 that a modification of the object distance causes a change of the angle.
Page 65: Units With Special Features
Photoelectric sensors 3.4.3 Units with special features A number of units with special features are offered for special applications. They will not be discussed as thoroughly as standard units. Foreground suppression In most cases interference of a diffuse-type sensor is caused by light objects in the background.
Page 66 Photoelectric sensors LED is used for this unit. At 565 nm it lights green (see 2.1.4). The sensing range is programmed to 13.5 mm (see Figure 129). Colours If the contrast sensor does not function satisfactorily, the use of the ODC colour sensor would be an alternative.
Page 67: Fibre Optics
Photoelectric sensors Fibre optics 3.5.1 Typical applications For what? Here, once again, the advantages of photoelectric sensors: - compact Compared to their sensing range the types are of very small design. This was already the case in the past. The use of microprocessors supports the trend towards more compact housings.
Page 68: Operating Principle
Photoelectric sensors glass fibres protective tube made of steel fibres metal-clad sheathing silicone sheathing Figure 57: Structure of fibre optics with metal and silicone sheathing Summary Special units have been developed for special operating conditions such as higher temperatures, splash water or installation in places which are not easily accessible: the photocells with fibre optics.
Page 69: Operating Principle
Photoelectric sensors Fibre optic The material they consist of is either glass or plastic. The characteristics of the different materials are described below. Sensing head This is a short overview of the different sensing heads. The complete technical data and dimensions are given in the catalogue or in the data sheets.
Page 70 Photoelectric sensors Figure 58: fibre optic as through-beam sensor Figure 59: fibre optic as diffuse reflection sensor Figure 60: principle of fibre optics as through-beam sensor Training manual...
Page 71: Notes On The Use Of Fibre Optics In Practice
Photoelectric sensors Figure 61: principle of fibre optics as diffuse reflection sensor 3.5.3 Notes on the use of fibre optics in practice Selection It has been explained in 3.5.1 under which special conditions the use of fibre-optic units is recommended. However, not every fibre optic is suited for every application.
Page 72 Photoelectric sensors optical characteristics during bending until they almost break. Glass fibres are chemically resistant. Glass fibres are more difficult to produce and thus more expensive. The sensing surface must be polished. Glass fibres cannot be cut to size by the user himself.
Page 73: Light-On And Dark-On Mode
Photoelectric sensors Irrespective of which material is used for the fibres the following points must be observed for handling fibre optics: 1. Do not bend fibre optics - risk of breakage for individual fibres or complete bundles of fibres. Consider the minimum bending radius (see data sheets) 2.
Page 74 Photoelectric sensors Dark If the light beam between transmitter and receiver is interrupted, i.e. no light strikes the receiver and the output switches - dark-on switching unit. Light If the light beam is however not interrupted, i.e. light strikes the receiver and the output is switched - light-on switching mode.
Page 75 Photoelectric sensors The different switching characteristics must be taken into account, in particular for the selection of units if a normally open or normally closed function is required at the output. Not all types have a programmable output signal (e.g. not type OU)! Once again Since experience has shown that in this context misunderstandings often occur the context will be explained and summarised once again in other...
Page 76: Excess Gain
Photoelectric sensors Excess gain 3.7.1 Meaning The operational reliability of the photoelectric sensors usually depends on the selected sensing range, on the application and on the selected type of unit. A good help for the selection of a certain type is provided by the excess gain graph.
Page 77 Photoelectric sensors Figure 62: Excess gain curve excess gain factor for step operating conditions diffuse retro- through reflection reflective beam sensors sensors sensors clean environments, lab rooms office rooms 2 for each 1.4 for each side = 4 side = 2 normal industrial environ- 4 for each 2 for each...
Page 78: Setting
Photoelectric sensors 3.7.2 Setting In general it is possible to set the sensitivity of photoelectric sensors, for some units by means of a potentiometer, for the units of the new generation by means of pushbuttons. The difference between these methods is to be explained below. Maximum sensitivity At the factory the sensitivity (of the receiver) is set to the maximum value.
Page 79 Photoelectric sensors Background The background provides the measured signal value 1. This should not affect the safe detection of the object. "Medium" In case of manual setting, whether by means of an electronic potentiometer such as for OB or a mechanical one for other units, the medium position is selected (see description above or 3.4.2.2).
Page 80: Switching Frequency
Photoelectric sensors or transformed: ( 7) has the index g because this formula is also called geometric mean. 2.24 For this example the result is approximately f = 2.24. This is the optimum switch point at which the excess gain factors with regard to object and background are the same.
Page 81 Photoelectric sensors Operational reliability In general, it has to be taken into consideration that the faster an optical system, the more it becomes sensitive to extraneous light. A photoelectric sensor using constant light reacts faster to an interruption of the light beam than a comparable unit using pulsed light.
Page 82 Photoelectric sensors 2. The mark-to-space ratio is not constant and the marks / spaces differ significantly (small objects and long spaces or large objects and short spaces). In this case a unit has to be chosen whose switching frequency still allows to safely detect the smallest pulse length or the shortest pause length.
Page 83: Examples Of Photoelectric Sensors
Photoelectric sensors Examples of photoelectric sensors Technology 4.1.1 Circuitry Processing and evaluation of signals What happens in the photoelectric sensors electronically? Figure 65: Block diagram through beam sensor Through-beam sensor The block diagram shows the functioning of a through-beam sensor. The transmitter unit contains the power supply, the cycle generator and the transmitter.
Page 84 Photoelectric sensors • For the through-beam sensor a high-pass filter in the receiver ensures that only high-frequency signals from the cycle generator of the transmitter are accepted by the receiver and amplified. So this excludes interference from extraneous light, e.g. the 100 Hz flickering of a fluorescent tube.
Page 85: Operational Reliability And Failure Warning
Photoelectric sensors Figure 67: block diagram diffuse reflection sensor Diffuse reflection sensor When comparing the block diagram of the diffuse reflection sensor with that of the retro-reflective sensor no difference can be seen. The only difference is that the light is not reflected by a prismatic reflector but by the object itself.
Page 86 Photoelectric sensors Let us now go to the technical implementation. The OV 310 / OV 110 amplifiers feature a digital noise suppression which increases the operational reliability even more. Figure 68: digital noise suppression 1 Figure 69: digital noise suppression 2 Via the pulsed transmitted light the signals which are reflected by the object or the reflector reach the receiver as pulses.
Page 87 Photoelectric sensors Switching frequency The price to pay for the gain in operational reliability is a reduction of the switching frequency. The shortest possible period is 2 x (time for 6 pulses), see below, example OF. Function display The units which are made in such a way (apart from the OV type also the OP which is no longer available today) also feature a special switching status display.
Page 88 Photoelectric sensors Figure 71: pulse diagram function display 4 states The binary standard sensor can only provide two pieces of information (0,1): • object detected • object not detected It is obvious to use another bit for the additional two pieces of information, that is to provide the unit with a second output for function check.
Page 89 Photoelectric sensors new units the function check output can be selected as an option or is even provided as a standard (see 4.2.2). Why not always? If it is so easy to increase the operational reliability, why not use units with function check output only? This has several reasons.
Page 90 Photoelectric sensors Evaluation of the signals The OF does not only detect whether an input signal has been received but it also evaluates its intensity and differentiates between 4 classes of input signals: Signal Output Range 1 no signal output not switched Range 2 unsafe signal output not switched...
Page 91: Current And Voltage Ranges
Photoelectric sensors described here. Thus a few points from 4.2 already have to be mentioned here. Internal faults (short circuit in the switching output) • The function check output is set, at the same time the LEDs signal as follows: The red and yellow LEDs flash alternately at about 3 Hz (for cable units the yellow LED flashes at this frequency).
Page 92: Leakage Current, Minimum Load Current And Voltage Drop
Photoelectric sensors 4.2.1 Leakage current, minimum load current and voltage drop Connection technology For a detailed description please see the corresponding training manuals. Here we will only briefly discuss one aspect which is especially important for photoelectric sensors. Note that it is normal for the 2-wire universal current units that a leakage current of up to 6 mA (OI) constantly flows to keep the unit ready for operation.
Page 93 Photoelectric sensors In Figure 78 and Figure 79 the normally open or normally closed symbol is used for simplification but the switching function is different for through-beam/retro-reflective sensors and diffuse reflection sensors. In addition photoelectric sensors have special features which are described below.
Page 94 Photoelectric sensors Caution! If an incorrect socket is used, the test input of the unit can be disabled. In case of a jumper between the respective pins, voltage is applied to the test input permanently. The transmitter is then permanently switched off. Receiver The variety of types is so great that not all versions can be listed here.
Page 95 Photoelectric sensors PIN 2 = fc-output Figure 79: Wiring diagram through-beam sensor receiver DC npn Function check output Like many other units the DC units are 3-wire units. Figure 78 and Figure 79 show a special feature. In addition to the normal switching output some units have a function check output (abbreviation fc).
Page 96 Photoelectric sensors Figure 80: wiring diagram OAE 100ms fc-out fault Figure 81: fc signal OAE The output provides an oscillating signal, e.g. when the lens or the reflector is soiled. A signal such as in Figure 81 is provided if for example a cloud of vapour passes between the object and the receiver.
Page 97: Handling
Photoelectric sensors The wiring diagram for the relay output of the OL (Figure 82) is also equivalent to that of the retro-reflective sensor. Diffuse reflection sensor As regards the switching output there is almost no difference between a diffuse reflection sensor and a retro-reflective sensor. The difference with regard to dark-on and light-on mode must be taken into account.
Page 98: Og As Through-Beam Sensor
Photoelectric sensors 4.3.1.1 OG as through-beam sensor transmitter receiver push button LED green LEDs red, yellow, green Figure 83: OGS, OGE Since the setting of the through-beam sensor is rare, it is not described here. The procedure is almost the same as for the retro-reflective sensor that is described below.
Page 99 Photoelectric sensors Yellow and green LEDs flash alternately (= unit is in the Press until the red LED flashes. programming mode). Place the object into the detection area*. The yellow and green LEDs go out for approx. 1s, then flash again alternately.
Page 100: Og As Diffuse Reflection Sensor
Photoelectric sensors 4.3.1.3 OG as diffuse reflection sensor Background For diffuse reflection sensors interference by the background is possible. In practice it is better to use a unit with background suppression. In cases where this is not possible, e.g. because of the shorter range with background suppression, it can however be necessary to set the range.
Page 101 Photoelectric sensors Activate the programming mode of the unit. Press for about 2s until the red LED flashes. The red LED goes out; the yellow and green LEDs flash alternately. The unit is in the programming mode. Set the sensitivity with object. Press once.
Page 102: Ogh As Diffuse Reflection Sensor With Background Suppression
Photoelectric sensors Activate the programming mode of the unit. Press for about 2s until the red LED flashes. The red LED goes out; the yellow and green LEDs flash alternately. The unit is in the programming mode. During the measurement (approx. 1s) allow at least two objects to move through the sensing area of the lens.
Page 103 Photoelectric sensors LED green is lit unit is ready for operation LED yellow is lit output is switched error in object detection, e.g. maladjustment, LED red is lit soiling of the lenses flashing alternately, 2 Hz: output short-circuited LEDs flashing alternately, 1 Hz: internal malfunction yellow + red (output is not switched) Display of the OF...
Page 104 Photoelectric sensors Latching The unit can be latched so that the switching threshold cannot be changed. The red LED lights for a short time, then the yellow and green LEDs flash alternately; after 10s the LEDs go out, Press for 10s. the unit is locked.
Page 105 Photoelectric sensors Yellow and green LEDs transmitter flash alternately; the intensity of the trans-mitted Press until the red LED flashes. light is increased. Align the transmitter precisely. transmitter The green LED is on; the transmitted light is set to normal intensity. Press once.* Figure 93: OGSL setting aid The first unit with standard function check output was the OA.
Page 106: Timers
Photoelectric sensors 4.3.2 Timers Timers, for what purpose? Since any timer function can be achieved by means of an electronic controller and sensors are normally connected to such a controller, this question is justified. The answer is to be summarised briefly. •...
Page 107 Photoelectric sensors One programming feature of the OS is to set an on or off delay for the output signal or to program that the output signal is always given as a pulse of the same length. The respective delays can be continuously set from 0.01 to 5 seconds by means of a second potentiometer on the unit (see Figure 96).
Page 108 Photoelectric sensors Figure 97: timer and output functions of the OV 310 Old and new The size of the OS and the OV 310 already shows that analogue circuitry is still used. The units of the new generation however have a processor which enables the same functions in much smaller housings (as for OB).
Page 109 Photoelectric sensors green LEDs: - in operating mode: excess gain in % - in programming mode: strength of input signal red LED: lights in the uncertain reception zone (maladjustment, soiling of the lens) delay T2: starts the setting of the pulse stretching yellow LED: switching status, lights when the output is switched green LED:...
Page 110 Photoelectric sensors This type still belongs to the generation of units with analogue circuitry. The dimensions or the volume of the unit already show this. As an option the OA provides a timer function which is set on the back of the unit: potentiometer 1 S1: output function sensitivity...
Page 111 Photoelectric sensors Objekt S1 = S1 = t' -t- Figure 102: OA position b This type also offers a timer function as an option. It is equivalent to that of the OA. The timer diagrams, Figure 101 and Figure 102, are the same. The setting is slightly different: programming switch delay...
Page 112: Mechanical Properties
Photoelectric sensors Mechanical properties 4.4.1 Designs and ranges The range is actually no mechanical but an optical property. But since it is related to the design, it makes no sense to treat this feature separately. 4.4.2 Mounting Is this important? You can take the following view: The manufacturer supplies a complete range of products.
Page 113 Photoelectric sensors Mounting arrangements First, the mounting types used in practice were analysed. It was found out that there are mainly three types of mounting. Many people use rods for mounting photoelectric sensors. When the mechanical layout of a plant is planned their use is intended right from the start.
Page 114 Photoelectric sensors Aluminium extrusion The aluminium extrusion is a frequently used component. To be able to use rod mounting again a cube type mounting component was developed. Since the actual cube (c) with the threaded hole shown in Figure 106 can be oriented in different directions another flexible and universal type of mounting was implemented with few components.
Page 115 Photoelectric sensors The clamp is fastened again around the bolt. Figure 108: Aluminium extrusion and clamp The following figures illustrate the versatility of the mounting system and what is meant by adapting free-standing and aluminium extrusion mounting to rod mounting with clamp. Figure 109: Rod for the aluminium extrusion Training manual...
Page 116 Photoelectric sensors Crank It can be seen in Figure 109 that this type of mounting poses no problem when the rod is longer than the aluminium extrusion. If this is not the case, i.e. more space is required for the clamp, a crank-shaped rod can be used.
Page 117 Photoelectric sensors Figure 111: Angle bracket (1) and clamp The sensor, here at the example of the type OG, is fixed using the angle bracket. Figure 112: Sensor and angle bracket (1) 2 fixing angles The clamp can be turned around the rod (of course before it is fixed with (b)).
Page 118 Photoelectric sensors Figure 113: Angle bracket (2) Figure 114: Angle bracket (3) Laser sensors Precise alignment is specially important for laser sensors. There is a special angle bracket which enables fine adjustment. Figure 115: Angle bracket for fine adjustment Training manual...
Page 119 Photoelectric sensors Figure 116: Angle bracket for fine adjustment with the sensor Other sensor types are mounted by means of other angle brackets. Figure 117: Angle bracket for OL Figure 118: Angle bracket for OL with sensor Training manual...
Page 120 Photoelectric sensors This example shows the angle bracket with protective shroud. Figure 119: Angle bracket for OL with protective shroud Prismatic reflector The same system can also be used to mount prismatic reflectors. For fixing suitable angle brackets are used. Two examples: Figure 120: Angle bracket for rectangular prismatic reflector Training manual...
Page 121 Photoelectric sensors Figure 121: Angle bracket for round prismatic reflector Fixture of OJ There is no space for drill holes etc. for fixing on the housing of the very compact new type OJ. Here type the housing has to be slid onto the fixture first.
Page 122: Lens Attachment
Photoelectric sensors There are more accessories for this fixture, e.g. a ball joint which is known in the field of photography. Figure 123: Swivel-mount for OJ 4.4.3 Lens attachment For the cylindrical designs OF and OJ a minimum length has to be taken into account.
Page 123 Photoelectric sensors Designation Type T/B Ret. Dif. LED IR LED R Laser Fibre rectangular ● ● 50*30*19 ● ● ● ● ● rectangular 51*16*28 ● ● ● 60*36*15 ● ● ● ● ● ● 42*49*15 ● ● ● ● ● 30*67*19 ●...
Page 124 Photoelectric sensors Designation Type T/B Ret. Dif. LED IR LED R Laser Fibre ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Notes The ● stands for "existing" or "available". To keep the table clear it is not shown which options exclude each other or can be combined.
Page 125: Units With Special Properties
Photoelectric sensors Units with special properties 4.6.1 Side or front lens A special characteristic of the OJ family is that virtually all units are available both with side and front lens. The very compact design is thus most effective. front lens* side lens* push button LED push button...
Page 126 Photoelectric sensors The following mistakes are often made when these units are used: 1. Wrong units are connected to the amplifier. 2. The opto efectors are connected to wrong amplifiers. 3. For reasons of cost the users try to build the amplifier themselves. 4.
Page 127: Contrast Sensor
Photoelectric sensors • Connection of 2 opto efectors, dark-on mode (D), light-on mode (H) and programmable (H*) • Connection of inductive and capacitive 2 or 3-wire efectors • Blocking the output signal on terminal 8 of the amplifier, e.g. as start- up delay for a machine •...
Page 128: Colour Sensor
Photoelectric sensors setting potentiometer sensitivity Figure 129: Setting of the contrast sensor Proceed as follows: 1. Set the potentiometer to the least sensitivity 2. Place the lighter of the two materials within the sensing range (light 3. spot must be on the object) 4.
Page 129 Photoelectric sensors LED operation display rotary switch colour tolerance teach button programming selector switch Out/OK Delay LED function display Figure 131: Operating panel of the colour sensor Set the rotary switch colour tolerance (Tolerance) to the requested colour resolu- tion. 1 = small tolerance range for detecting small colour shades 3 = basic setting...
Page 130 Photoelectric sensors After a successful teach-in operation the function display (Out/OK) comes on. If it flashes, the intensity is too high. Incline the sensor by 10 ... 30° and repeat the teach-in operation. If the function display is not lit, the inten- sity is too low.
Page 131: Infrared Sensors
How? (brief explication) In principle, the efector 200 infrared sensors are photoreceivers which receive the heat radiation of the object to be detected and convert it into a switching signal.
Page 132: Degree Of Emission
Photoelectric sensors which indicate: "object detected" or "object not detected" with the only difference that they emit no rays. To enable detection the object only needs to emit a sufficient amount of heat radiation. But they can also be used similar to a photoelectric sensor. If they are set to a warmer background and the light beam is interrupted by a colder object, they can operate as described above, only with the function being reversed.
Page 133: Technology
Photoelectric sensors Some values for emission degrees are indicated in the attached table. Note the wide range of the values between 0.01 and 0.95! Due to the different degrees of emission it is possible in practice that the switching response of the infrared sensors is not the same for different objects despite the same surface temperature.
Page 134 Photoelectric sensors Figure 133: Overview of the infrared sensors The electronics of the infrared sensors consist of a photoelement with a preamplifier, an evaluation and an output stage. The photoelement of the types OWS, OWL and OWF with a temperature range of 350 °C to 500 °C consists of Germanium elements, silicon elements are used for the range from 750 °C to 900 °C.
Page 135: Information On Practical Use
Photoelectric sensors Information on practical use One advantage of the non-contact temperature detection as compared to other methods is that there is no mechanical connection between the sensor and the surface of the object, and thus the chemical compatibility between sensor and medium is more or less no problem. Non-contact temperature sensors detect temperature radiation as it is registered by our skin when a hot object is nearby.
Page 136 Photoelectric sensors What is the angle of aperture? It is up to you to decide which angle (α or α/2) is referred to as angle of aperture. There is no need to lay this down in standards. For small angles it is not necessary to be too precise.
Page 137 Photoelectric sensors An infrared sensor with a switching temperature of 350 °C and an angle of aperture of 1° is selected. If the object to be detected is much bigger than the calculated sensing zone, this results in a high excess gain (e.g. to compensate for a dirty lens).
Page 138 Photoelectric sensors Figure 136: Diagram angle of aperture - sensing distance – diameter Degree of coverage If the degree of coverage is below 100%, the following measures must be taken to enable correct switching: select another sensor with a lower switching temperature reduce the range increase the object temperature The temperature response diagram below shows by how many degrees...
Page 139: Setting Instructions For Owi
Photoelectric sensors 5.2.2 Setting instructions for OWI The units with a variable temperature setting have an angle of aperture of 7°. The following diagram represents the sensing area depending on the range. For a reference emitter (E=0.99) the switch point can be set in a temperature range of +50 °C to +500 °C.
Page 140: Operating Conditions
Photoelectric sensors Output 1 is to switch at 130 °C. Output 2 is to switch at 150 °C. Figure 139 demonstrates the switching response of the sensor depending on the temperature. The outputs 1 and 2 can be logically combined as follows: •...
Page 141 Photoelectric sensors Mounting For easy mounting a robust mounting base can be obtained as an accessory. High operating temperatures For operating temperatures above +60 °C a fibre optic must be used which can withstand up to +250 °C. For the fibre optics attachment lenses with an angle of aperture of 2°...
Page 142 Photoelectric sensors Hot steel sheets In rolling mills hot steel sheets are detected using infrared sensors. Figure 140: Detection of hot steel sheets The high temperature poses a problem when a sheet which is still glowing passes the sensor very slowly. Dust trickling down can settle on the lens.
Page 143: Applications
Photoelectric sensors Applications Photoelectric sensors Strictly speaking, the infrared sensors also belong to this group. Since their function and applications are different from those of the other sensors they are treated in a separate chapter (see 6.2) as was done with their technical features.
Page 144: Application Examples
Photoelectric sensors Size The size of the objects also is a selection criterion. For very small objects or little mounting space units with fibre optics or separate amplifiers are well suited. Lasers are particularly suited for small objects. 6.1.2 Application examples The following figures show a few examples of the numerous applications of photoelectric sensors.
Page 145 Photoelectric sensors Edge monitoring For paper, plastic or textile webs through-beam and diffuse reflection sensors are used for edge and sag monitoring. Figure 142: Edge monitoring Monitoring the filling operation The sensors check whether the cartons on a conveyor belt are filled. Empty cartons are rejected.
Page 146 Photoelectric sensors Monitoring a conveyor Photoelectric sensors detect objects at a larger distance, e.g. on a conveyor for metal plates. Figure 144: Monitoring a conveyor Storage technology Use of a retro-reflective sensor to monitor the height of a pile. Figure 145: Retro-reflective sensor in storage technology Training manual...
Page 147 Photoelectric sensors Anti-collision protection Photoelectric sensors are used as anti-collision detectors on a crane. The beam is oriented obliquely. Thus the beam only hits the prismatic reflector when the distance between the objects is too close. Doubling the sensors results in double safety. Note! The description of Figure 146 only concerns the safety of the machine.
Page 148 Photoelectric sensors Figure 147: Background suppression Monitoring material on cutting machines Diffuse reflection sensors type OI used to monitor material on an automatic cutting machine. A fault is signalled in case of a tear. Figure 148: Monitoring material on a cutting machine Training manual...
Page 149 Photoelectric sensors Monitoring the supply of material Control of an automatic saw with a diffuse reflection sensor type OU. It monitors the material supply and controls activation of the drive. Figure 149: Monitoring the material supply Detection of contact lugs Photoelectric sensors with fibre optics are suitable for the detection of minute parts due to their optical properties.
Page 150: Infrared Sensors
Photoelectric sensors Infrared sensors Examples In chapter 5 the properties and operating conditions of the infrared sensors have already been described. Since there are only few infrared types and applications, it is not necessary to give a summary, some examples are given straight away. Infrared sensors are used where a non-contact safe detection of very hot and glowing parts is required.
Page 151 Photoelectric sensors Figure 151: Continuous casting machine Length monitoring Infrared sensors monitor the length of hot steel pipes. Figure 152: Length monitoring Training manual...
Page 152 Photoelectric sensors Slabs Infrared sensors are used to monitor slabs and hot rolled sheets in the steel industry. Figure 153: Slabs Flames Infrared sensors monitor open flames of burners and waste gas burners. Figure 154: Flames Note This should be taken into account: •...
Page 153 Photoelectric sensors Products from induction furnaces Detection of hot production goods from an induction furnace. Figure 155: Goods from an induction furnace Hot rolled wires Infrared sensors with fibre optics monitor hot rolled wires for break. Figure 156: Hot rolled wires Training manual...
Page 154 Photoelectric sensors Glass bottles Infrared sensors count hot glass bottles in the hollow glass industry. Figure 157: Glass bottles Note This should be taken into account: • The cycle frequency can increase due to the various bottle sizes and thus bottle diameters. •...
Page 155 Photoelectric sensors Note This should be taken into account: • Glass dust can soil the lens in the long term. • The operating temperature in the background should be much lower than that of the objects. • The background should be free from reflections caused by interfering heat sources.
Page 156 Photoelectric sensors Jam bottling Temperature monitoring during food bottling is important because of the best before date guarantee. Figure 160: Jam bottling . Note This should be taken into account: • Different compositions of food may lead to different radiation intensities at identical temperatures due to different degrees of emission.
Page 157 Photoelectric sensors Soldering systems Infrared sensors are used to detect the position of PCBs in a soldering system. Figure 161: Soldering system Note This should be taken into account: • The temperature within the cover of the soldering system can exceed 100 °C.
Page 158 Photoelectric sensors Coating of profiled rails When profiled rails are coated with plastic infrared sensors are used for temperature monitoring. Figure 162: Coating of profiled rails Edge banding For edge banding of wooden boards and pressboards in the furniture industry it is quickly monitored without contact whether glue is applied to the edge.
Page 159: Type Keys
Photoelectric sensors Appendix Type keys Type key opto efectors Pos. Designation Contents Sensing principle O = optical Design 1 = distance sensor 2 = 2D sensor 5 = rectangular housing 55,9 x 18,2 x 46,7 A = rectangular housing 90 x 70 x 30 B = rectangular housing 60 x 36 x 15 C = rectangular housing 50 x 43 x 15 D = rectangular housing 53 x 30 x 96...
Page 160 Photoelectric sensors Type key opto efectors Output system B = semiconductor output for AC or AC/DC units C = semiconductor output PNP and NPN N = semiconductor output negative switching P = semiconductor output positive switching K = contact output (relay) O = no output function (transmitter) S = serial interface 1 = analogue output 4 ...
Page 161 Photoelectric sensors Type key fibre optics Pos. Designation Contents System fibre optics Mode of operation T = diffuse-type sensor E = through-beam sensor U = universal Reserve Amplifier to be connected 00 = OKF, OUF 11 = OBF 18 = OGF 30 = OIF 50 = ODF, OMF, (OBF) X = special type...
Page 162 Photoelectric sensors Type key infrared heat sensors Pos. Designation Contens System O = Infrared heat sensor Function W = heat Type I = infra sensor (M30) L = long type S = short type Additional designation - = standard Switching temperature 35 = 350 °C 50 = 500 °C 75 = 750 °C...
Page 163: Production Code
Photoelectric sensors Explanation production code The coding is indicated on the type and box labels of our products or on an alternative type of labelling, e.g. 'direct laser labelling' as it is used with the units in modular technology. The coding covers information about Legend 'production site' ifm ecomatic, Kressbronn production site...
Page 164: Table Degree Of Emission
Photoelectric sensors Table degree of emission The specifications in the table are only average values because the degree of emission of a material is influenced by different factors such as: temperature sensing angle geometry of the surface (flat, concave, convex) thickness surface characteristics (polished, rough, oxidised, sandblasted, etc.) Material...
Page 165 Photoelectric sensors Material Aluminium not oxidised 0.02...0.10 oxidised 0.02...0.40 Aluminium alloy A 3003 oxidised roughened 0.10...0.30 polished 0.02...0.10 Brass polished 0.01...0.05 high-polished 0.30 oxidised 0.50 Copper polished 0.03 roughened 0.05...0.10 oxidised 0.40...0.80 Gold 0.01...0.10 Haynes alloy 0.30...0.80 Inconel oxidised 0.70...0.95 sandblasted 0.30...0.60 electropolished...
Page 170: Glossary Of Technical Terms
Photoelectric sensors Glossary of technical terms Absorption When a ray of light passes through a medium, radiation (or part of it) is converted into another form of energy (e.g. heat) and is thus "lost". This process is called absorption. Background suppression For applications with interfering high-contrast background behind the object to be sensed diffuse reflection sensors with background suppression are used.
Page 171 Photoelectric sensors Infrared Radiation with a wave length greater than that of visible light is called infrared radiation (IR), often also denoted as ultrared radiation. Three ranges are differentiated: IR - A 780 nm to 1400 nm IR - B 1400 nm to 3000 nm IR - C 3000 nm to 25000 nm.
Page 172 Photoelectric sensors Operating temperature The operating temperature of the opto efector must be within the range specified in the data sheet. It must not exceed the maximum value or fall below the minimum value. Operating voltage The nominal operating voltage is a value for which electrical equipment is rated.
Page 173 Photoelectric sensors Retro-reflective sensor A light barrier where the light of the transmitter-receiver is reflected by a reflector located within the optical axis is called a retro-reflective sensor (IEC 60947-5-2). The optical means of the transmitter can also serve for receiving the reflected light.
Page 174: Index
Photoelectric sensors Index 13,5 mm ............... 127 cable length ............125 cap................39 Caution ..............94 ceramics industry........... 150 4 stati...............88 changeover contacts ..........96 characteristics..........35, 47, 55 characteristics of diffuse reflection sensors ....58 6 pulses..............86 characteristics of the retro-reflective sensor ..47, 53 characteristics of the through-beam sensors....
Page 175 Photoelectric sensors digital ..............85 digital noise suppression ..........86 GaAlAsP..............19 DIN 5031 ..............13 GaAs................19 directional..............25 GaAsP ..............19 discharge monitoring ..........150 gate circuit ...............85 dispersion ............11, 170 geometrical optics............14 display ..............102 glass.................69 distance ............36, 135 glass bottles ............154 duality..............10 glass fibre..............71 dust .................15 glossary..............170 dynamic .............59, 80, 101 glowing hot spots ..........150...
Page 176 Photoelectric sensors object..............79 object size ............. 135 lacquer ..............141 OC ................ 127 laser ........24, 25, 34, 37, 104, 112 OCK ................ 65 laser and prismatic reflector ........50 OCNL ..............65 laser diod ..............20 OCPG..............53 laser diode ...............25 OCV ................
Page 177 Photoelectric sensors slabs...............150, 152 slot.................114 quality of a prismatic reflector........51 small objects ..........28, 65, 67 quantum..............15 socket ..............94 quenching assemblies ..........150 soiling ..............14, 88 solar radiation ............19 soldering systems ...........157 radiation ..............172 spacers..............41 range ..34, 47, 51, 56, 63, 64, 65, 136, 140, 172 spectral curves ............20 ratio on/off ..............83 spectral distribution..........18...
Page 178 Photoelectric sensors wave ............... 10 wave length ........11, 12, 13, 14, 132 velocity of light..........11, 29 wear and tear............83 versatile..............67 wet areas ..............71 voltage drop............ 92, 173 white............... 23 wiring diagram ............97 wafers ..............150 waste gas burners ..........

IFM Electronic Efector 200 Training Manual

1 Introduction

2 Light

3 Characteristics of Photoelectric Sensors

4 Examples of Photoelectric Sensors

6 Applications

5 Infrared Sensors

Index

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