L18 Photoelectric Linear Encoder

by Precizika Metrology

The sealed linear encoder L18 is used to convert linear displacements of key machine components into electrical signals containing information about the value and direction of the displacement.

The encoder consists of a glass scale installed into a rigid hollow housing and a ball-bearing-guided reading head. To be able to work in harsh environments (lubricants and chips), the encoder has sealing lips.

Filtered air can be supplied into the housing of the encoder for extra protection.

The photoelectric unit of the reading head generates sinusoidal micro-current or TTL square-wave (standard RS422) output signals.

Three versions of output signals are available:

  • L18-A - Sinusoidal signals, with amplitude approx. 11 µApp, require external subdividing electronics.
  • L18-AV - Sinusoidal signals, with amplitude approx. 1 Vpp, require external subdividing electronics.
  • L18-F - Square-wave, with integrated subdividing electronics for interpolation x1, x2, x5, x10, x25, x50.

MECHANICAL DATA

 

Measuring lengths (ML), mm 70; 120; 170; 220; 270; 320; 370; 420; 520; 620; 720; 820; 920; 1020; 1140; 1240 (other intermediate lengths on request)
Accuracy grades to any metre within the ML (at 20°C) ±10; ±5; ±3 µm (optional)
Grating period 20 µm; 40 µm (optional)

Reference marks (RI);

-standard for ML ≤1020  mm

-standard for ML >1140 mm

-optional

35 mm from both ends of ML 45 mm from both ends of ML one RI at any location, or two or more RI's separated by distances of n x 50 mm or distance-coded

Max. traversing speed:

-when interpolation factor is 1, 2, 5, 10

-when interpolation factor is 25

-when interpolation factor is 50

-1 m/s

-0.5 m/s

-0.4 m/s

Required moving force with sealing lips < 3 N

Protection (IEC 529)

-without compressed air

-with compressed air (optional)

IP53

IP64

Weight 0.4 kg + 0.8 kg/m   
Operating temperature 0...+50 °C    
Storage temperature  -20....+70°C
Permissible vibration (40 to 2000 Hz) ≤30 m/s²
Permissible shock (11 ms) ≤100 m/s²

ELECTRICAL DATA

VERSION L18-A ∼ 11 µApp L18-AV ∼ 1 Vpp L18-F  TTL
Power supply +5V ± 5% / <90 mA +5V ± 5% <120 mA +5V ± 5% / 120 mA
Light source LED LED LED
Resolution Depends on external subdividing electronics Depends on external subdividing electronics 5; 2.5, 1; 0.5;  0.2; 0.1 µm (after 4-fold dividing in subsequent electronics)
Incremental signals

two sinusoidal l¹ and l² Amplitude at 1 kOhm load:

-l1 = 7-16 µA

-l2 = 7-16 

Differential sine +AV-A and +B/-B

Amplitude at 120 Ohm load:

-A = 0.6-1.2V

-B = 0.6-1.2V 

Differential square-wave U1/U¯1 and U2/U¯2

Signal levels at 20 mA load current: 

-low (logic "0")≤0.5V

-high (logic "1")≥2.4V

 

Reference signal One quasi-triangular lº = 2-8 µA (usable componenet)

One quasi-triangular +R and its complementary -R per revolution.  Signals magnitutde at 120 Ohms load

- R = 0.2-0.8V (usable component)

One differential square-wave U0/U0 per revolution.  Signal levels at 20 mA load current:

-low (logic "0") <0.5V

-high (logic "1") >2.4V

Maximum operating frequency 50 kHz 50 kHz

50xk kHz, when interpolation factor is 1, 2, 5, 10

1000 kHz when interpolation factor is 25, 50

Direction of signals l² lags l¹ at reading head displacement from left to right B+ lags A+at reading head displacement from left to right U2 lags U1 at reading head displacement from left to right
Standard cable length 3 m, without connector 3 m, without connector 3 m, without connector
Maximum cable length 5 m  25 m  25 m

Note:  If cable extension is used the power supply conductor section should not be smaller than 0.2 mm²