Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL Reed Switch Basics OKI Sensor Device Corporation
Engineering Department 2015 0961 1/11
Slide 2
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 2 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.
Slide 3
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 3 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. Inert gasor vacuumGlass
tubeHermetic seal PB-free lead solder Permalloy (Fe+Ni) Gold (Au)
Rhodium (Rh)+[Iridium (Ir)] A layer of Au & a PG metal is
applied upon the pressed permalloy 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.
Slide 4
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 4 OFF State Operation ON State Operation N poleS pole
N pole Inert gasor vacuum Reed blade contacts PB-free lead solder
Glass tubeHermetic seal
Slide 5
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 5 Shipment Permalloy leads Glass tube Reed blade
Sealing Machine Plating Machine Sealing portion (Both top and
bottom) Undercoat Surface Plating Reed blade Permalloy lead Cut and
Press Cut & Press Magnetic Annealing Contact surface plating
Surface treatment Glass sealing Solder dip Electrical inspection
Physical inspection Packaging Final inspection K1 K2 Annex
Slide 6
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 6 Sealing Machine Sorting MachineCut & Pressing
Machine
Slide 7
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 7 Glass sealing is achieved using in-house designed
and produced automated sealing machines [Surface Treatment] After
plating on the reed blades 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 switchs 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
MeasurementPhysical Examination] All reed switches under electrical
characteristics and physical examination [Glass Sealing Automation]
[Magnetic Flux Scanning]
Slide 8
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 8 ORD229 / ORD2210 / ORD2210V ORD325 ORD324H ORD324
ORD2211 ORD2211H ORD228VL Rh Ir
Slide 9
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 9 ORT551 ORD211 ORD311 ORD213 ORD2221 ORD221 ORD219
ORD312
Slide 10
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 10 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.
Slide 11
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 11
Slide 12
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 12 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 Position 3: Lines of
magnetic force flow through ON When magnetic drive is applied,
depending on the magnet position the ON & OFF operating
position may vary. Depending on the magnetic fields direction, the
ON and OFF ON & OFF operating position may vary. With a strong
magnet OR with a high sensitivity reed switch(AT is small) there
are areas on the far edges of the terminals that are ON operating
positions(3 point operation).
Slide 13
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 13 Case 1: X-Y Characteristic (Horizontal)Case 2: X-Z
Characteristic (Horizontal) 90Clockwise Case 3: X-Y Characteristic
(Vertical) Magnet 90Clockwise
Slide 14
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 14 AT is big Low Sensitivity AT is small High
Sensitivity
Slide 15
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 15
Slide 16
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 16 Stop Lamp Switch Lamp Expiration Sensor Seatbelt
Sensor Engine Temperature Sensor Power Seat Position Sensor Fuel
Tank Level Indicator Seat Position Sensor Brake Fluid Level
Indicator (FLI) Airbag Sensor Speed Sensor 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(NO X ) in exhaust gas. Liquid Ammonia Tank
Dosing Control Engine Oxidation SCR Post treatment Temperature
Sensor Selective Catalytic Reduction System Window Wash Tank Level
Indicator Liquid Ammonia Tank Level Indicator Brake Fluid Level
Indicator (FLI) Engine Oil Level Indicator Fuel Tank Level
Indicator
Slide 17
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 17 Rice Cooker Washing Machine Air Conditioner Dish
Washer Refrigerator Temperature Sensor Oneba Sensor Pot Sensor
Open/Close Sensor Cleaner Position Sensor Open/Close Sensor
Temperature Sensor Open/Close Sensor
Slide 18
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 18 Bidet Toilet Seat Coffee Maker Electric Shaver
Humidifier Electric Toothbrush Electric Hot Pot Water Level Sensor
Power ON/OFF Switch Water Level Sensor Power ON/OFF Switch
Slide 19
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 19 Electric Thermometer Open/Close Sensor Flow Sensor
Reset Switch Gas Meter Water Heater Capacity Sensor Rotation Sensor
Magnetic Sensor Bicycle Meter Slot Machine Electric Reel IC Tester
Security Systems Reed Relay Power ON/OFF Switch
Slide 20
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 20 Airbag Shock SensorFlow Sensor Float Level
SensorPinball Sensor
Slide 21
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 21 End of line Sensor Speed Sensor Seat Belt Sensor
Rotation Sensor
Slide 22
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 22 Reed Switch Traits Advantages ON State resistance
is low, OFF state resistance is high No operating electricity
needed Can handle direct loads of DC/AC Usable in any
environment
Slide 23
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 23 Thanks for your support!
Slide 24
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL Supplemental Information 24
Slide 25
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 25 Example of Reed Switch operation
Slide 26
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 26 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
Slide 27
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 27 Washing Machine Lid Open/Close sensor Reed switch
installed in unit Magnet enclosed in lid
Slide 28
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 28 Smart Meters (Gas, Water) Flow of water/gas is
measured by the rotation of the magnet triggering counting over the
reed switch circuit. Magnet mm
Slide 29
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 29 Water Level Sensor Coffee Maker/Electric Water Pot)
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. 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.
Magnet Float Full Empty Pump Heater
Slide 30
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 30 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.
Slide 31
Copyright 2015 Oki Electric Industry Co., Ltd. S OSDC
CONFIDENTIAL 31 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.