Photoelectric Sensors Technical Guide

Transcription

1 Explanation of Terms Photoelectric Technical Guide Item Explanatory diagram Meaning distance Set range/ range Directional angle Through-beam Retro-reflective Diffuse-reflective Limited-reflective Mark (Contrast scanner) Distance-settable and and and and distance distance distance Upper end of the sensing distance range Lower end of the sensing distance range Center sensing distance and range range Set range Directional angle of the Reflector beam θ θ Reception area beam The maximum sensing distance that can be set with stability for Through-beam and Retro-reflective, taking into account product deviations and temperature fluctuations. Actual distances under standard conditions will be longer than the rated sensing distances for both types of Sensor. The maximum sensing distance that can be set with stability for the Diffuse-reflective, taking into account product deviations and temperature fluctuations, using the standard sensing (white paper). Actual distances under standard conditions will be longer than the rated sensing distance. As shown in the diagram at left, the optical system for the Limited-reflective is designed so that the axis and the axis intersect at the surface of the detected at an angle θ. With this optical system, the distance range in which regular-reflective light from the can be detected consistently is the sensing distance. As such, the sensing distance can range from 10 to mm depending on the upper and lower limits. (See page 7.) As shown in the diagram of the optical system at the left, a coaxial optical system is used that contains both an emitter and a receiver in one lens. This optical system provides excellent stability against fluctuations in the distance between the lens and the sensing (i.e., marks). (With some previous models, the emitter lens and receiver lens are separated.) The sensing distance is specified as the position where the spot is smallest (i.e., the center sensing distance) and the possible sensing range before and after that position. Limits can be set on the sensing position of s with Distance-settable. The range that can be set for a standard sensing (white paper) is called the "set range." The range with the set position limits where a sensing can be detected is called the "sensing range." The sensing range depends on the sensing mode that is selected. The BGS mode is used when the sensing is on the Sensor side of the set position and the FGS mode is used when the sensing is on the far side of the set position. (See page 6.) Through-beam, Retro-reflective The angle where operation as a Photoelectric Sensor is possible. Differential travel and Reset distance Operating distance ON OFF Diffuse-reflective and Distance-settable The difference between the operating distance and the reset distance. Generally expressed in catalogs as a percentage of the rated sensing distance. Differential travel Dead zone Example for Diffuse-reflective Sensor Dead zone Emission area Reception area The dead zone outside of the emission and reception areas near the lens surface in Mark, Distance-settable, Limited-reflective, Diffuse-reflective, and Retro-reflective. Detection is not possible in this area. Response time Light input Control output Operating time (Ton) Reset time (Toff) The delay time from when the light input turns ON or OFF until the control output operates or resets. In general for Photoelectric, the operating time (Ton) reset time (Toff). 9

2 Photoelectric Technical Guide Item Explanatory diagram Meaning Dark-ON operation DARK ON Through-beam, Retro-reflective Diffuse-reflective and Present Operation Operation Not present The "Dark-ON" operating mode is when a Through-beam Sensor produces an output when the light entering the is interrupted or decreases. Light-on operation LIGHT ON Through-beam, Retro-reflective Diffuse-reflective and The "Light-ON" operating mode is when a Diffuse-reflective Sensor produces an output when the light entering the increases. Not present Operation Operation Present Ambient operating illumination Difference between Ambient Operating Illumination and Operating Illumination Limit Operation illumination limit Received light output 100% Ambient operating illumination Received Illumination paper ±0% Reflector lamp Received light output for 00 lx 00 1,000 10, ,000 Illumination (lx) The ambient operating illumination is expressed in terms of the surface illuminance and is defined as the illuminance when there is a ±0% change with respect to the value at a light reception output of 00 lx. This is not sufficient to cause malfunction at the operating illuminance limit. Lux meter Standard sensing Through-beam Retro-reflective and Retroreflector Diffuse-reflective and paper Emission beam The length of the diagonal of the lens or lens The length of the diagonal of the Reflector A bigger piece of blank paper than the diameter of the beam The standard sensing for both Through-beam and Retro-reflective is an opaque rod with a diameter larger than the length of a diagonal line of the optical system. In general, the diameter of the standard sensing is the length of the diagonal line of the / lens for Through-beam, and the length of a diagonal line of the Reflector for Retro-reflective. Size of Standard Object Using Reflector Reflector models Diagonal line of optical system E9-R1/R1S/R1K 7. mm 7-mm dia. E9-R mm 10-mm dia. E9-R mm 4-mm dia. E9-R mm 0-mm dia. E9-R6 6.7 mm 60-mm dia. E9-R9 4.7 mm 4-mm dia. E9-R mm 70-mm dia. E9-RS1 6.4 mm 40-mm dia. E9-RS.1 mm -mm dia. E9-RS 106. mm 110-mm dia. E9-R7 1.4 mm 1-mm dia. For Diffuse-reflective, the standard sensing is a sheet of white paper larger than the diameter of the emitted beam. 10

3 Photoelectric Technical Guide Item Explanatory diagram Meaning Through-beam Minimum sensing Retro-reflective and Diffuse-reflective Reflector Typical examples are given of the smallest that can be detected using Through-beam and Retro-reflective with the sensitivity correctly adjusted to the light-on operation level at the rated sensing distance. For Diffuse-reflective, typical examples are given of the smallest s that can be detected with the sensitivity set to the highest level. and Minimum sensing with slit attached Slit Through-beam Typical examples are given of the smallest that can be detected using Through-beam with a Slit attached to both the and the as shown in the figure. The sensitivity is correctly adjusted to the Light-ON operating level at the rated sensing distance and the sensing is moved along the length and parallel to the slit. 11

4 Photoelectric Technical Guide Application and Data (1) Relationship of Lens Diameter and Sensitivity to the Smallest Detectable Object With a Through-beam Sensor, the lens diameter determines the size of the smallest that can be detected. With a Through-beam Sensor, a small can be more easily detected midway between the and the that it can be off center between the and. As a rule of thumb, an 0% to 80% of the lens diameter can be detected by varying the sensitivity level. Check the Ratings and Specifications of the Sensor for details. Maximum sensitivity Lens diameter 80% of the lens diameter Adjusted sensitivity Lens diameter 0% of lens diameter The size given for the smallest that can be detected with a Reflective Photoelectric Sensor is the value for detection with no s in the background and the sensitivity set to the maximum value. Detects s 80% of the lens diameter. Detects s up to 0% of the lens diameter. () Detecting Height Differences Selecting Based on Detectable Height Differences and Set Distances (Typical Examples) distance Difference in height 40 Appearance to 00 mm ±1.8mm 11 to 1 mm 0 ±mm 40 to 00 mm Features 0.7 to 0.4 mm mm 0.8 to 1.0 mm 4 to 0 mm min. 0.8 to 4 mm Optical Fiber Built-in Amplifier Microsensors Separate Amplifier Built-in Amplifier Built-in Amplifier Model E-LL ET-SL1@ EC-LSR EZ-LS ES-CL1 14

5 Photoelectric Technical Guide () MSR (Mirror Surface Rejection) Function [Principles] This function and structure uses the characteristics of the Retroreflector and the polarizing filters built into the Retro-reflective to receive only the light reflected from the Retroreflector. The waveform of the light transmitted through a polarizing filter in the changes to polarization in a horizontal orientation. The orientation of the light reflected from the triangular pyramids of the Retroreflector changes from horizontal to vertical. This reflected light passes through a polarizing filter in the to arrive at the. [Purpose] This method enables stable detection of s with a mirror-like surface. Light reflected from these types of s cannot pass through the polarizing filter on the because the orientation of polarization is kept horizontal. Retroreflector Corner Cube Vertically polarizing filter Longitudinal wave [Examples] A sensing with a rough, matte surface (example ()) can be detected even without the MSR function. If the sensing has a smooth, glossy surface on the other hand (example ()), it cannot be detected with any kind of consistency without the MSR function. Transverse wave Horizontally polarizing filter (1) No Object The light from the hits the Reflector and returns to the. () Non-glossy Object Light from the is intercepted by the, does not reach the Reflector, and thus does not return to the. () Object with a Smooth, Glossy Surface (Example: battery, can, etc.) Light from the is reflected by the and returns to the. [Caution] Stable operation is often impossible when detecting s with high gloss or s covered with glossy film. If this occurs, install the Sensor so that it is at an angle off perpendicular to the sensing. 1

6 Photoelectric Technical Guide Retro-reflective with MSR function Retro-reflective with MSR function Classification by Configuration Model Optical Fiber E-R1, E-R16 EZ-R61/R66/R81/R86 Built-in Amplifier EZM-R61/R66/R81/R86/B61/B66/B81/B86 EZM-CR61(-M1TJ)/CR81(-M1TJ) ES-CR11(-M1J)/CR61(-M1J) Separate Amplifier EC-LR11/LR1 Built-in Power Supply Note: When using a Sensor with the MSR function, be sure to use an OMRON Reflector Vertically polarizing filter Reflected light (longitudinal wave) OMRON Retroreflector Vertically polarizing filter Reflected light (transverse wave) Glossy OMRON Retroreflector Horizontally polarizing filter Emitted light (transverse wave) Horizontally polarizing filter Emitted light (transverse wave) Retro-reflective without MSR Function When detecting a glossy using a Retro-reflective Sensor without the MSR function, mount the Sensor diagonally to the so that reflection is not received directly from the front surface. Retro-reflective without MSR Function Classification by Configuration Model Transparent Object EZ-B61/B6/B66/B67/B81/B8/B86/B87 16

7 Photoelectric Technical Guide (4) Surface Color and Light Source Reflectance Surface Color Reflectance Reflectance of Various Colors at Different Wavelengths of Light 70 Reflectance (%) Blue LED LED Red LED Violet Blue Yellow Red Blue LED (470 nm) LED (6 nm) Red LED (680 nm) Wavelength (nm) Identifiable Color Marks Sensor Light Color : Blue Sensor Light Color : Sensor Light Color : Red Red Yellow Blue Violet Black 8 Red Yellow Blue Violet Black The numbers express the degree of margin (percentage of received light for typical examples). Models with an RGB light source support all combinations Sensor light color Product classification Model EX-HD EX-SD Optical Fiber EX-NA Red light source EX-DA-S EX-MDA EC-VSR Separate Amplifier EC-VMR EC-VS7R Blue light source Optical Fiber EX-DAB-S Red Yellow Blue Violet Black 8 Red Yellow Blue Violet Black Red Yellow Blue Violet Black Red Yellow Blue Violet Black light source light source Optical Fiber Separate Amplifier Optical Fiber EX-DAG-S EX-NAG EC-VS1G EX-DAC-S 17

8 Photoelectric Technical Guide () Self-diagnosis Functions The self-diagnosis function checks for margin with respect to environmental changes after installation, especially temperature, and informs the operator of the result through indicators and outputs. This function is an effective means of early detection of product failure, optical axis displacement, and accumulation of dirt on the lens over time. [Principles] These functions alert the operator when the Sensor changes from a stable state to an unstable state. The functions can be broadly classified into display functions and output functions. Display function Stability Indicator (green LED) The amount of margin with respect to environmental changes (temperature, voltage, dust, etc.) after installation is monitored by the self-diagnosis function and indicated by an indicator. (Illuminates steadily when there are no problems.) Operation Indicator (Orange LED) Indicates the output status. Output function The margin is indicated by an indicator light, and the state is output to alert the operator. [Purpose] Self-diagnosis functions are effective in maintaining stable operation, alerting the operator to displacement of the optical axis, dirt on the lens (Sensor surface), the influence from the floor and background, external noise, and other potential failures of the Sensor. Incident light 1.1 to to 0.9 Control output ON (L ON) OFF Self-diagnosis ON output OFF Indicator (L ON) 0. s min.* Orange 0. s min.* () 1.1 to 1. () 0.8 to 0.9 * If the moving speed of sensing is slow, the Sensor may output a self-diagnosis output. When using the Photoelectric sensor, please install an ON-delay timer circuit etc.. Operation Indicator*: Orange Stability Indicator: * Some may have an incident light indicator (red or orange), but it depends on the model. 18

9 Photoelectric Technical Guide Example: Light-ON Operation Indicator state Degree of margin with respect to temperature changes indicated by the green indicator Light-ON/Dark- ON indicated by the orange indicator Self-diagnosis output Example of diagnosed condition Stability indicator Operation indicator Orange Stable use is possible. (Margin of 10% to 0% or higher) (Stability indicator: ON) x 1.1 to 1. Stability Operation indicator indicator Light Incident orange indicator ON Example: Incident light becomes unstable. (1) When the optical axis shifts slightly due to vibration. Orange () When the lens became dirty from adhesion of dust. Dirt Stability indicator Operation indicator Orange Light Interrupted orange indicator OFF The margin is not sufficient. ( indicator: OFF) When this state continues for a certain period of time, an output alerts the operator. Example: Operation is unstable when light is interrupted. (1) Light has leaked around the sensing (Through-beam or Retro-reflective ). () Reflected light from the floor or the background has been received (Diffuse-reflective Sensor). () External noise has influenced operation. x 0.8 to 0.9 Noise Stability indicator Operation indicator Orange Stable use is possible. (Margin of 10% to 0% or higher) (Stability indicator: ON) <Applicable Models> Classification by Configuration Optical Fiber Separate Amplifier Built-in Amplifier Models Self-diagnosis function Display function Output function EX-DA-S Digital display EX-MDA Digital display --- EX-NA --- EC-LDA Digital display EC (EC-JC4P) EZ --- EZM(-C) --- ET --- ES-C --- ES-CL