Reed Switch Basics OKI Sensor Device Corporation Engineering
Reed Switch Basics OKI Sensor Device Corporation Engineering Department 2015 技管資‐ 0961 1/11 © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL
Products A switch composed of two (reed) blades created from magnetic material and sealed with inert gas. The switching mechanism relies on external magnetic waves to magnetize the blades and initiate contact. Common Applications © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 2
Reed Switch Structure & Operational Theory Glass tube(Hermetic seal) Inert gas(or vacuum) Permalloy (Fe+Ni) PB-free lead solder A layer of Au & a PG metal is applied upon the pressed permalloy Gold (Au) Rhodium (Rh)+[Iridium (Ir)] A reed switch consists of; Two reed blades made from ferromagnetic permalloy Glass Tube Plating applied to the contact surfaces Nitrogen based inert gas pumped into the glass tube Pb-free solder dipped terminals • Contact surface are plated with platinum group metals, such as iridium and rhodium. • Contact surfaces also go under oxygen treatment to stabilize contact resistance. • The fusing machine brings two reeds and a glass tube together to form the reed switch. Placing a magnetic field close to the reed switch induces a magnetic north and south pole in the ferromagnetic permalloy leads. The contact surfaces attract and close in what is considered the ON state. As the magnetic field is removed the contacts are restored and open into the OFF state. © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 3
Reed Switch Operation OFF State Operation Reed blade contacts PB-free lead solder Inert gas(or vacuum) Glass tube(Hermetic seal) ON State Operation N pole S N S pole © Copyright 2015 Oki Electric Industry Co. , Ltd. S pole N pole S OSDC CONFIDENTIAL 4
Reed Switch Production Flow Permalloy leads Glass tube Cut & Press Magnetic Annealing K 1 Glass tube Contact surface plating Permalloy lead Sealing Machine Surface treatment Reed blade Cut and Press K 2 Glass sealing Solder dip Reed blade Sealing portion (Both top and bottom) Electrical inspection Physical inspection An ne Undercoat x Packaging Final inspection Shipment Plating Machine © Copyright 2015 Oki Electric Industry Co. , Ltd. Surface Plating S OSDC CONFIDENTIAL 5
Production Equipment Sealing Machine Sorting Machine © Copyright 2015 Oki Electric Industry Co. , Ltd. Cut & Pressing Machine S OSDC CONFIDENTIAL 6
Propriety engineering that ensures quality [Glass Sealing Automation] Glass sealing is achieved using in-house designed and produced automated sealing machines [Surface Treatment] [Magnetic Flux Scanning] After plating on the reed blade’s contact surface, the blades undergo high temperature oxidation treatment. This treatment removes moisture and carbon particles from the surface, leading to stable electrical resistance throughout the reed switch’s lifespan. As the reed switch contains ferromagnetic leads there is a probability that particles end up inside the glass of the reed switch. Alongside electrical characteristics measurement, the below process of magnetic flux scanning removes particles from all reed switches. [Electrical Measurement・Physical Examination] All reed switches under electrical characteristics and physical examination © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 7
Reed Switch Lineup (1/2) Rh Ir ORD 324 ORD 229 / ORD 2210 V ORD 325 ORD 324 H ORD 2211 ORD 228 VL ORD 2211 H © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 8
Reed Switch Lineup (2/2) ORT 551 ORD 2221 ORD 211 ORD 221 ORD 219 ORD 213 ORD 311 ORD 312 © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 9
The sensitivity of OKI Reed Switches are measured using the OKI Standard Coil. ↓ Other brands of reed switches have sensitivities which may not be equivalent. © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 10
© Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 11
・When magnetic drive is applied, depending on the magnet position the ON & OFF operating position may vary. ・Depending on the magnetic field’s direction, the ON and OFFで、ON & OFF operating position may vary. Case 1: X-Y Characteristic (Horizontal) Position 1: Lines of magnetic force flow through → ON Position 2: Lines of magnetic force do not flow through → OFF With a strong magnet OR with a high sensitivity reed switch(AT is small) there areas on the far edges of the terminals that are ON operating positions(3 point operation). © Copyright 2015 Oki Electric Industry Co. , Ltd. Position 3: Lines of magnetic force flow through → ON S OSDC CONFIDENTIAL 12
Case 1: X-Y Characteristic (Horizontal) Case 2: X-Z Characteristic (Horizontal) 90°Clockwise Case 3: X-Y Characteristic (Vertical) Magnet 90°Clockwise © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 13
AT is small (High Sensitivity) © Copyright 2015 Oki Electric Industry Co. , Ltd. AT is big (Low Sensitivity) S OSDC CONFIDENTIAL 14
© Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 15
Seatbelt Sensor Airbag Sensor Stop Lamp Switch Engine Temperature Sensor Lamp Expiration Sensor Window Wash Tank Level Indicator Brake Fluid Level Indicator (FLI) Seat Position Sensor Speed Sensor Fuel Tank Level Indicator Power Seat Position Sensor 【 Selective Catalytic Reduction System 】 Oxidation Engine Dosing Control SCR Post treatment Temperature Sensor Liquid Ammonia Tank Equipped with a liquid ammonia tank, this liquid is sprayed into the exhaust gas to produce ammonia gas. This ammonia gas is then used in the treatment of nitrogen oxides(NOX) in exhaust gas. © Copyright 2015 Oki Electric Industry Co. , Ltd. Brake Fluid Level Indicator (FLI) Engine Oil Level Indicator Liquid Ammonia Tank Level Indicator S OSDC CONFIDENTIAL Fuel Tank Level Indicator 16
Rice Cooker Refrigerator Washing Machine Temperature Sensor O・ne・ba Sensor Pot Sensor Temperature Sensor Open/Close Sensor Air Conditioner Dish Washer Open/Close Sensor Cleaner Position Sensor © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 17
Bidet Toilet Seat Coffee Maker Power ON/OFF Switch Water Level Sensor Electric Shaver Electric Hot Pot Electric Toothbrush Water Level Sensor Humidifier Power ON/OFF Switch © Copyright 2015 Oki Electric Industry Co. , Ltd. Water Level Sensor S OSDC CONFIDENTIAL 18
IC Tester Reed Relay Security Systems Electric Thermometer Open/Close Sensor Power ON/OFF Switch Electric Reel Rotation Sensor Slot Machine Bicycle Meter Magnetic Sensor © Copyright 2015 Oki Electric Industry Co. , Ltd. Gas Meter Water Heater Flow Sensor Reset Switch Capacity Sensor Rotation Sensor S OSDC CONFIDENTIAL 19
Airbag Shock Sensor Flow Sensor Float Level Sensor © Copyright 2015 Oki Electric Industry Co. , Ltd. Pinball Sensor S OSDC CONFIDENTIAL 20
Rotation Sensor Speed Sensor End of line Sensor Seat Belt Sensor © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 21
Reed Switch Traits (Advantages) ・ ON State resistance is low, OFF state resistance is high ・ Can handle direct loads of DC/AC ・ Usable in any environment ・ No operating electricity needed © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 22 -
Thanks for your support! © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 23
Supplemental Information © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL 24
Example of Reed Switch operation © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 25 -
Refrigerator door open/close sensor With the reed switch set in the main unit, opening the door opens the reed switch beginning a timer. When the timer reaches a certain count an alarm sounds. Magnet enclosed in the door © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 26 -
Washing Machine Lid Open/Close sensor Magnet enclosed in lid Reed switch installed in unit © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 27 -
Smart Meters (Gas, Water) Flow of water/gas is measured by the rotation of the magnet triggering counting over the reed switch circuit. Magnet m3 © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 28 -
Water Level Sensor(Coffee Maker/Electric Water Pot) Pump Heater Float Full Magnet ・As the float with magnet inside goes down with the water level, the [Empty] switch turns ON to stop the heater. ・As the water empties, water is pumped in and stops when the [Full] switch turns ON. Empty © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 29 -
Multiple point fluid level sensor (Gasoline/Diesel Tank) With magnets fitted into the floats, as the fluid level fluctuates the multiple switches turn off and on to indicate the level of fluid. © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 30 -
Power Windows detection sensor 2 Reed switches on the motor detect the change in rotation speed. Magnets on the motor gear turn the switches to the ON state allowing detection of the rotation direction and rotation speed. © Copyright 2015 Oki Electric Industry Co. , Ltd. S OSDC CONFIDENTIAL - 31 -
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