L18B Photoelectric Linear Encoder

by Precizika Metrology

The sealed linear encoder L18B 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.

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:

  • L18B-A - Sinusoidal signals, with amplitude approx. 11 µApp, require an external subdividing electronics.
  • L18B-AV - Sinusoidal signals, with amplitude approx. 1 Vpp, require external subdividing electronics.
  • L18B-F - Square-wave signals, with integrated sub-dividing electronics for interpolation x1, x2, x5, x10, x25, x50.

MECHANICAL DATA

Measuring lengths (ML), mm 70; 120; 170; 220; 270; 320; 370; 420; 470; 520; 620; 720; 820; 920; 1020; 1140; 1240; 1340; 1440; 1540 1640; 1740; 1840; 1940; 2040; 2140; 2240; 2340; 2440; 2540; 2640; 2740; 2840; 2940; 3040; 3140; 3240 (other intermediate lengths on request).

Accuracy grades to any metre within the ML (at 20°C):

- for ML 70 to 2040

- for ML 2040 to 3240

 

 

 

±10; ±5 µm

 

±10 µm

 

Grating period 20 µm; 40 µm (optional)

Reference marks (Rl):

-standard for ML ≤1020 mm

-standard for ML >1141 mm

-optional

35mm from both ends of ML

45mm from both ends of ML

one Rl at any location, or two or more Rl'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

 

IP53

 

IP64 

Weight  0.4 kg + 1.0 kg/m  
Operating temperature  0...+50°C
Storage temperature  -20...+70°C
Permissible vibrations (40 to 2000 Hz) ≤30 m/s²      
Permissible shock (11 ms) ≤100 m/s²                                                                                                                   

ELECTRICAL DATA

VERSION L18B-A ∼ 11 µApp L18B-AV ∼ 1 Vpp L18B-F   TTL
Power supply +5V ± 5% /< 90 mA
Light source LED LED LED
Resolution Depends on external subdividing electronics Depends on external subdividing electronics 5; 1; 2.5; 0.5; 0.2; 0.1 µm (after 4-fol dividing in subsequent eleectronics)
Incremental signals

Two sinusoidal l¹² and l² Amplitude at 1 kOhm load:

- l¹ = 7-16 µA

- l² = 7-16 µA

Differential sine +A/-A and +B/-B Amplitude at 120 Ohm Load:

- A = 0.6-1.2 V

- B = 0.6-1.2V

Differential square-wave U1/U1¯ and U2/U2¯.  Signal levels at 20 mA load current:

 - low (logic "0") ≤0.5V

- high (logic "1") ≥2.4V

Reference signal

Quasi-triangular l°, signal magnitude at 1 kOhm load:

-l° = 2-8 µA

Quasi-triangular +R and its complementary -R. Signals magnitude at 120 Ohm load -R = 0.2-0.8V

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 

50xl 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 0.5 mm2.