Nidec Copal RE20F Incremental Rotary Encoder

The Rotary Encoder series includes optical and magnetic encoders. Optical models run from φ 12 to φ 30 and include small, light weight, and low cost models, as well as high resolution, and manual setting models.


The Rotary Encoder series includes optical and magnetic encoders. Optical models run from φ 12 to φ 30 and include small, light weight, and low cost models, as well as high resolution, and manual setting models. These encoders can be used to sense the angle, size and rotation speed of industrial equipment, including industrial robots, numerically controlled (NC) machine tools, elevators, production equipment, terminals at financial institutions, computer peripheral equipment, etc. They can also be used as manual setting encoders for digital equipment, such as measuring, communications and medical equipment.


Optical encoders

The light from the LED which passes through the slit of the rotating disk actuates the photo-sensor. The output of the photo-sensor which is quasi-sinusoidal is shaped into square wave by the voltage comparator and fed into a logic circuit.

Magnetic encoders

Principle structure is composed of magnetic sensor and magnetic drum (corresponding to LED and photo-sensor in an optical encoder). Without power consuming LED, total dissipation power of the magnetic encoder is far less than that optical encode

Magnetic encoders
Magnetic encoders


Quasi-sinusoidal signal output (RE20F)

Output signals of the RE20F rotary encoders are direct signals from the photo-sensor in the quasi-sinusoidal wave form. An external circuit is therefore required to shape them into square wave signals. Fig. 3 shows the output amplitude variation (ripple), ΔEs which is defined as follows.

Square wave signal output

(REC16, RES16, RES20D, REC20D, RESW20D, RECW20D, RMS20, REC20, RES20B, REC20C, RE12D, RE30E)

Output signals of the series encoders are in the form of square waves and can be fed into a digital circuit directly
without an interface. There are three versions available, for 5 V output, 12 V output and 24 V output.


Output “Z” : This is an index output of one pulse per turn and is used as a reset signal or start signal. The encoders are so designed that there will be only one rising edge on CW rotation (falling edge on CCW rotation) in the output “B” during the time period when the output “Z” is “high”. Therefore, an ideal reference position signal can be obtained by getting the outputs “B” and “Z”.
Output “A” : This is a basic output and will give as many pulses per turn as the resolutinon.
Output “B” : This output is the same as the output “A” except that there is an electrical phase difference of 90° between the output “A” and “B” and is used to sense the direction of rotation.

The rotating direction is usually determined by sensing the signal level of the output “B” at the pulse edge of the output “A”.


The maximum operating speed of the encoders is given by the following formula.
Maximum speed (min-1) = Maximum frequency response (Hz) × 60/ Resolution (P/R)
Note) Encoders exceeding the above limit may be available on a special order basis.


Nidec Copal

Nidec Copal

NIDEC COPAL ELECTRONICS was established in April 1967 in Japan as a specialty manufacturer of electronics components. The company's philosophy remains unchanged - to be a supplier of high quality products while offering competitive prices. NIDEC COPAL ELECTRONICS began by developing a wirewound trimmer. This product was enthusiastically received by many sectors in the industry. The initial success of the trimmers laid the groundwork for future development of a wide selection of manufactured products that combined electronics at the start of the electronics revolution.

Later, robust sales of cermet trimmers led to the company's remarkable expansion. Further development efforts led to the release of a succession of new product lines. These included a wide range of motors, encoders, switches and pressure sensors.


  • Two-phase output
  • Compact, dia.: 20 mm
  • Low torque, low inertia
  • RoHS compliant


  • Input equipment for lmage simulation, e.g. CAD
  • Cursol position setting for wave observation of Oscilloscope etc.
  • Level settings for ultrasound imaging devices
  • For manual setting of broadcasting system, e.g. switcher


Electrical characteristics

Output phases1 phase “A” only2 phase  “A” & “B”
Photo-sensor maximum current45 mA maximum (at 25 °C)
Output wave formQuasi-sinusoidal
Output phasesAA, B
Resolution (P/R)100, 300100
Phase difference of outputs A & B———90° ± 45°
Maximum frequency response———12 kHz
Output signal150 mVp-p minimum ※11 Vp-p minimum
Output signal amplitude variation ※240 % maximum
Light sourceLED
※ 1 Measured at CP1 in the fig.A of ‘MEASUREMENT CIRCUIT’ on the following page.
※ 2 One phase only : Measured at CP2 in the fig.A of ‘MEASUREMENT CIRCUIT’ on the following page.

Mechanical characteristics

Starting torque0.05 mN·m {0.5 gf·cm} maximum
Inertia0.2 g·cm2  maximum
Shaft loading
(When mounting)
Radial1.96 N {200 gf} maximum
Axial4.9 N {500 gf} maximum
Net weightApprox. 15 g

Environmental characteristics

Operating temp. range0 ~ 50 °C
Storage temp. range−20 ~ 80 °C
Protection gradeIP40

Reliability Test

Test itemTest conditions
VibrationPower OFFAmplitude : 1.52 mm or 98.1 m/s2 (10 G) whichever is smaller.
10 ~ 500 Hz excursion 5 min/cycle, 1 hour each for X, Y, Z, directions.
ShockPower OFF1 time each in 6 directions (X, Y, Z) at 490 m/s2 (50 G), 11 ms.
High temperature
Power OFF80 °C  96 h(To be measured after leaving samples for 1h at normal temperature and humidity after the test.)
Power ON50 °C  96 h
Low temperature
Power OFF-20 °C  96 h
Power ON0 °C 96 h
HumidityPower OFF40 °C Relative humidity 90 〜95 % 96 h
(To be measured after wiping out moisture and leaving samples for 1h at normal temperature and humidity after the test.)
Thermal shockPower OFFTo be done 10 cycles with the following condition
(To be measured after leaving samples for 1 h at normal temperature and humidity after the test.)
70 °C 1 h、‐20 °C 1 h


⦿ LED(at 25 °C)
Maximum current45 mA
Reverse voltage4 V
Power dissipation (PD)75 mW
Temp. derating of PD (25 ~ 60 °C)−1.4 mW/°C
⦿ Photo-sensor(at 25 °C)
Collector current20 mA
Collector to emitter voltage (forward)20 V
Collector to emitter voltage (reverse)5 V
Collector dissipation (PD)75 mW
Temp. derating of PD(25 ~ 60 °C)−1.0 mW/°C


Part Number Designation


Series name

Resolution (P/R)

100, 300

Output phase

1:“A” only

2:“A” & “B” (100 P/R only)

List of Part Numbers

Part numberOutput phasesResolution
RE20F-100-100“A” only100 (P/R)
RE20F-300-100“A” only300 (P/R)
RE20F-100-200“A” & “B”100 (P/R)

Additional Information


External Schematics

⦿ 2 phase 100 P/R

Internal Circuit

⦿ 1 phase 100・300 P/R

⦿ 2 phases 100 P/R

Measurement Circuit

⦿ 1 phase 100・300 P/R

⦿ 2 phases 100 P/R


Unless otherwise specified, tolerance: ± 0.4 (Unit: mm)


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