- Principle of optical encoder operation
- Scale list for encoder evaluation
- Evaluation tools information download
Principle of optical encoder operation
Optical encoders are sensor products to measure the position and either linear displacement or rotational angle
Linear Encoders (Linear movement)
Rotary Encoders (Rotation)
Structure of optical encoder
【SMD-01B】
Encoder structure example
To measure the amount of movement, LED light is irradiated onto a pattern on a linear or rotary scale fixed to the object, the reflection of which is received by the *light-receiving element(Photo diode array) converted into an electronic signal and output.
Photo diode array is includes in OEIC
Difference between "Reflective" and "Transmissive" encoder
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Reflective encoder
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A Light emitting element and a light-receiving element will be located on the same surface. LED light is irradiated onto a pattern on a linear or rotary scale fixed to the object, the reflection of which is received by the light-receiving element.
Seiko NPC optical encoder is reflective encoder.AdvantageSmaller size/Less component and thin.
Easy to assemble due to less componentsDisadvantage-
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Transmissive encoder
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A light-receiving device(Photo diode) will detect the light emitted from LED passed through the slit located on the code wheel.
AdvantageNo special design technology required
・Matured tecnology designDisadvantageIncreasing the number of components
Complex manufacturing skill required.
Incremental encoders & Absolute encoders
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Incremental encoders : Relative position detection
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Relative displacement/angle from original position will be measured
After system shut off, information of original position will be lost. When system is resumed, information of original position needs to be restored by using Z-phase signal.
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Absolute encoders : Absolute position detection
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Displacement/angle from original position can be directly measured
Not only displacement but also position can be determined
Linear encoders & Rotary encoders
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Linear Encoder
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Measure the linear movement
Example SMD-01B : 20μm/cycle
By counting the number of cycles, total amount of displacement can be calculated.【Application】
XY-stage, Measuring Gauge
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Rotary Encoder
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Measure the rotational movement
By counting the number of cycles, total amount of rotational angles can be calculated.【Application】
Motor, Robotics
Scale list for encoder evaluation
| Product Name | Rotary/Linear | Scale Material | Size |
|---|---|---|---|
|
SMD-01B
|
Rotary
|
Glass
|
AB(Z) 4000PPR
φ30/13.4mm |
|
Linear
|
Glass
|
AB L=30mm
ABZ L=30mm
|
|
|
SMD-04B
|
Rotary
|
Glass
|
ABZ 4000PPR
φ30/13.4mm |
|
Linear
|
Glass
|
AB L=30mm
ABZ L=30mm
|
|
|
SME-08A/B
|
Rotary
|
Metal
|
865/500PPR
φ26/4mm |
|
Linear
|
PET
|
L=100mm
|
|
|
SM3414B
|
Linear
|
PET
|
L=52.5mm
|
If you have any inquiry about evaluation scale, please contact us through below inquiry form.
Scale Vendors
Scale vendors who support Seiko NPC encoders are like following
| Vendor | Address | Phone# | URL | |
|---|---|---|---|---|
|
Koshibu Precision Co.,Ltd.
|
2-20-11 Hayamiya, Nerima-ku,
Tokyo 179-0085, Japan |
|||
|
Meltec Corporation
Sales Dept. |
1038 Nagareyama,
Nagareyama City, Chiba 270-0164, Japan |
|||
|
ALPHASEIKO CO.,LTD
Sales Department, Encoder Unit |
315-1
Shimo-ongatamachi, Haptiolish, Tokyo, 192-0154, Japan |
Evaluation tools information download
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