overview Sensors are differentiated depending on applied edia. Light, one of the edia, is also utilized for a which is called a photoelectric. It is a non-contact type which is applicable to sensing presence, passing, size, color and brightness of the object. Classification by sensing ethod s can be classified into three categories depending on sensing type. Through-bea photoelectric Through-bea bea type is to detect a using the difference of light intensity depending on presence of with placing an eitter and a receiver face to face. Long sensing distance is available and it is not affected by background. Eitted light Retroreflective photoelectric Retroreflective type(standard type) Retroreflective type uses a photoelectric which is integrated with eitter and receiver, and a reflector with high light radiant in order to detect a by coparing difference of light aount deterined by the presence of between the and reflector. Eitted light Eitted light Using highly reflective objects is liited but depends on install ethod, it could be available to use. Retroreflective type(built-in polarized filter) Like standard type of retroreflective photoelectric, polarized filter type uses a photoelectric which is integrated with eitter and receiver and reflector. The eitter part and receiver part in the have each polarized filter for receiving reflected light fro the reflector which ake the light polarized at 90. filter A Eitted part Horizontal polarized filter filter B part Mirror surface object filter A Vertical polarized filter filter B Diffuse reflective photoelectric Diffuse reflective is to detect a by direct reflection off the object. ( / in one body) Standard diffuse reflective type Light source is diffused after passing the lens, detects a by coparing difference of light aount which depends on size, color and brightness of the object. Narrow bea type Narrowed bea spot size after passing the lens has little effect on background. It is suitable for sensing in narrow space or sensing sall size of the object. Convergent reflective type Convergent reflective type sensed liited area (checked part) where optical source across. In the figure below, the sensing at (A) can be detected while the at (B) cannot. Due to detecting liited area by optical source, there is little effect by background but it is not siple to odify sensing distance and sensing in a specific area (within 50). BGS(Background Suppression) type It detects range of set distance which is applied the algorith of triangulation principle which is for easuring the place where the reflected light fors an iage on the receiving or the optical syste. Also it has little effect by size, color and surface condition of the sensing and no effect on the background. Strong at teperature, power and voltage changes and available detect to sensing distance over 10. Triangulation : light fors an iage on the receiving light after being reflected on the sensing. In case sensing is located at (B), sae aount of reflected light will be received on both N and F part of receiving. In case sensing is located closer (A), larger aount of reflected light will be received on N part and less aount of light on F part. In case sensing is located further (C), both N and F part will receive the reflected light vice versa. Therefore, sensing distance can be deterined with calculating the aount of reflected light on both parts of receiving (Two-segent photodiode). N F (Two-segent photodiode) LED Received part Eitted part range (A) Aount of incident light on F = Aount of incident light on F + range Aount of incident light on N range (B) Setting distance (A) (B) (C) A-72
Glossary LED : Light Diode A seiconductor diode that eits light when an electric current passes through it. The color and brightness of LED is deterined by the coponent, construction ratio, ipurities of PN junction for iproving single crystal which is ade with galliu(ga) to ixed crystal. Infrared LED : Using P-N junction for GaAs Red LED : Adding ipurities Zn, O to GaP Green LED : GaP/Green light eitting/ Yellowish green eitting is used due to low efficiency. Yellowish green LED : Adding N to GaP / Higher eitting efficiency than Green eitting. The ost coon eitting for photoelectric is IRED having high eitting efficiency and large outputs. Red or green LED is also frequently used according to applications. Photo diode A photo diode is a type of diode capable of converting light into either current or voltage when light reached to P layer. PN or PIN junction used. Si is generally used for seiconductor. PIN photodiode is coonly used as receiving s to catch optical signal with high response and frequency. Applicable to photoelectric s receiving s, PCM transission for optical counication, and TV/ VTR reote s receiving parts. Photo transistor Copared to photo diodes, photo transistor has aplifying action by transistor. Control easily due to high receiving sensitivity for Base current. Thus it is available in a wide range of photoelectric s. The sensing serves as a reference for easuring basic perforance. Bea angle Angle range for noral sensing by the s. s bea angle Operation ode Light ON Output switching s (transistor or Relay) becoe ON when the receiver receives eitting light fro the eitters. Dark ON Output switching s (transistor or Relay) becoe ON when the receiver receives ON lights fro the eitters. Retroreflective Diffuse reflective Through-bea Hysteresis (Reflective type) Distance difference between operating distance and returning distance. Response tie The tie lag between light received point and the point on which output operation becoes ON.(Light ON) Generally, response tie is represented as operation tie (Ton). [Operating tie (Ton) Returning tie (Toff)] Output / Interrupted light ON OFF Light ON Operating tie (Ton) Major features Returning distance Operating distance Returning tie (Toff) Dark ON ON OFF Hysteresis Non-contact detection is a non-contact type which does not have any ipact on the sensing. Wide range of sensing Applicable to a wide range of aterials including transparent glass, etal, plastic, wood and liquid. High speed response tie Using light as the ediu, it is able to sensing high speed oving object. Superior distinction perforance Using several characteristics of light, various kinds of s are developed. They are able to detect presence, passing, size, color, and brightness of the sensing. Easy to control application environent Easy to control sensing range and environent of photoelectric using lens such as half irror, shield boards, slit. (A) Photo electric (B) Fiber optic (C) Door/Area (D) Proxiity (E) Pressure (F) Rotary encoder (G) Connector/ Socket (H) Tep. (I) SSR/ Power (J) Counter (K) Tier (L) Panel (M) Tacho/ Speed/ Pulse (N) Display unit (O) Sensor (P) Switching ode power supply (Q) Stepper otor& Driver&Controller (R) Graphic/ Logic panel (S) Field network device (T) Software (U) Other A-73
Low influence fro agnetic field and vibration Using light when photoelectric detect the sensing, it is less affected by agnetic and vibration. Color identification The rate at which an object reflects or absorbs light depends on both the wavelength of the eitted light and the color of the object. This property can be used to detect colors. objects of diffuse reflective type s distance according to color Relative sensing distance(%) 850 350 170 100 100 100 90 50 20 40 110 350 170 A B C D E F G H I J K L It shows ratio of sensing object each detection distance based on non-glossy white paper is 100%. Relative sensing distance depends on the odel and sensing object size. Convergent reflective type is not affected by color or aterial within range of sensing distance as specified in chart. distance and range against the sensing condition As the reflectivity of the sensing surface is high, the sensing distance is long. As the size of the sensing is big, the sensing distance is long. As the rate of reflection of the sensing is low, the sensing area is narrow. However in the case of white non-glossy paper, it has lower reflectivity than glossy SUS or aluinu, but the property of sensing area is better by diffused reflection of the surface of the white paper. 70 A: Non-glossy white paper(standard) B: Corrugated card board with yellow color C: Veneer board D: Non-glossy black paper(brightness 3) E: Bakelite board with yellow color Acrylic board (black) Vinyl resin (red) 850 28 35 42 F: Vinyl resin (orange) G: Rubber board H: Aluinu board I: Reflective bar J: Rusty steel bar ø10 K: Black cloth (towel) L: Dark Blue cloth(towel) Feature data The following describes about the feature data. Exaple of parallel shifting characteristic (Through-bea type) This characteristic for through-bea type, indicates about width of light for the eitter. As shown in the figure, the receiver 1, 2, 4 operate norally but the receiver No. 3 does not operate norally because it is out of the width of light. Refer to this data when placing several s in parallel, it is able to prevent utual inference. In case installing the receiver at 9 point (as 2 in the figure), there ust be 110 interval between each unit in order to prevent utual interference. distance characteristic (Diffuse reflective type) This is feature data of diffuse reflective type s sae as the parallel shifting characteristic. Angle characteristic (Through-bea type, Retroreflective type) After fixing the eitter(or reflector), and the receiver() oves towards the center axis fro right or left, up or down until operation becoes OFF. distance L () 15 12 9 6 3 0 200 150 100 50 0 50 100 150 200 ❶ Left Right Operation position() angle characteristic (Retroreflective type) Move a reflector towards center axis fro right or left, up or down with fixing the receiver until operation becoes OFF. Retroreflective type ❷ ❹ ❸ : distance, : Sensor angle Retroreflective type : distance, : angle A-74
Proper usage Precaution for proper installation Make sure enough sensing space(sensing stability) when selecting and installing the. Make sure that dia of lens (Ø) is saller than sensing when selecting the. If there are any possibilities to be daaged by sensing s, use protection covers for protecting photoelectric s. In case the is applied to high frequency achines, such as ultrasonic welding achine, etc, insulate the and high frequency achines using insulating boards to prevent alfunction fro induced current. Keep the cable as short as possible. In case of cable extension, ake sure that thickness of the cable shall be over 0.3 2. Be careful of voltage drop. is generally applied for achine, or equipent. It is easy to have the effect of vibration or shock. In order to prevent this effect, please following countereasures before using. 1 Do not ake s ain body touch the sensing directly. 2 Use sturdy aterial supports in order not to be affected by vibration or shock. 3 Tighten fixed bracket s bolts and nuts. If photoelectric lens are dirty by dust, clean with a dried towel softly. Do not use organic solvent, such as thinners, etc. Avoid dust or any corrosion causing environents. Countereasures for utual interference In the case of using the photoelectric s closely, you should ake countereasures because of interference which affects each other s operation. Through-bea type 1 Increase the separation distance with referring to parallel shifting feature data. distance L () L Left Right area [Parallel shifting characteristic feature data] 2 or ore 2 or ore 2 Place the eitter and the receiver alternately. In this case, if the install distance of the photo is close like [Figure 1], it can cause alfunction. User needs to install a shield like [Figure 2]. 3 Narrow the light by using slits on the receiver. Diffuse reflective type, convergent reflective type 1 Check the install distance which has no interference at the sensing area characteristics of the. Install the with the 2 ties longer operating position(l1) than sensing distance(l). 2 Install shield between s. 2 or ore distance L () [Figure 1] [Figure 2] Slit(BYD3M-ST) Placing a shield Left Right area L (A) Photo electric (B) Fiber optic (C) Door/Area (D) Proxiity (E) Pressure (F) Rotary encoder (G) Connector/ Socket (H) Tep. (I) SSR/ Power (J) Counter (K) Tier (L) Panel (M) Tacho/ Speed/ Pulse (N) Display unit (O) Sensor (P) Switching ode power supply (Q) Stepper otor& Driver&Controller (R) Graphic/ Logic panel (S) Field network device (T) Software (U) Other [ area feature data] A-75
Influence of surroundings Through-bea type Eitted light is not copletely interrupted by a sensing because soe aount of eitted light gets reflected fro the ounting board and enters into the receiver. Optical axis 2. Attach slits or protection cover on the receiver. Disturbance light Slit [Countereasure 1] [Countereasure 2] Optical axis Diffuse reflective type 1. Effect of install surface In case a diffuse reflective is ounted on a rough ounting plate, the reflected light causes photoelectric s alfunction. For prevent this, please ount the with bracket. Mounting board 2. Effect of the surrounding object Even though the surrounding object such as wall is far apart fro the sensing, the object is able to affect the detection. Countereasure: 1 Paint the background in black color to reduce reflected light. 2 Increase the distance fro the background. 3 Select convergent reflective type. Influence of disturbance light There are two types of photoelectric s which are odulated type and non-odulated type. Modulated type is not affected by noral disturbance light. But it can be affected by strong disturbance light or odulated disturbance light. Strong disturbance light : Direct rays of sunlight Modulated disturbance light : Arc welding spark, Inverter fluorescent. 1. Set the optical axis of the receiver ore than 30 difference with the entering light direction of disturbance light. (Set exceed the range of light width) Operation power and grounding In case of coercial power, use power supply with low noise/voltage variations. Avoid using the unit around the power generators or high voltage lines. Do not connect high voltage power source line and s cable power line together. It ay cause product daage or alfunction. Please wire lines separately. < Iproper connections > In case of DC power photoelectric s, use insulation transforer for rectified power supply with ±10% ripple. Secondary Priary In case power is supplied fro switching ode power supply, ensure that the frae ground (F.G.) terinal of the power supply is connected to an ground and connect a condenser for noise reoval between 0V and F.G. terinal. (Usually the condenser is equipped in switching ode power supply units) Switching ode +V power supply 0V (S.M.P.S.) F.G Insulation transforer < Proper connections > Condenser for noise:0.001 to 0.1 μf /400V Frae High voltage line/ Power supply line Metallic pipe +V 0V In case of s aterial is etal, ground the etal case to prevent electrostatic or product alfunction due to noise. + - + - High voltage line/ Power supply line Metallic pipe Min. 30 Disturbance light Precaution for power supply Please do not operate the s ON/OFF by power. It is required at least 500s for stable operations after power supply is ON. A-76