3

State Width Error (

∆S): The

deviation, in electrical degrees, of

each state width from its ideal

value of 90

°e.

Phase (

φ): The number of

electrical degrees between the

center of the high state of channel

A and the center of the high state

of channel B. This value is

nominally 90

°e for quadrature

output.

Phase Error (

∆φ): The deviation

of the phase from its ideal value

of 90

°e.

Direction of Rotation:

When the

codewheel rotates in the direction

of the arrow on top of the

module, channel A will lead

channel B. If the codewheel

rotates in the opposite direction,

channel B will lead channel A.

distance from the codewheel's

center of rotation to the optical

center (O.C.) of the encoder

module.

number of electrical degrees that

an index is high during one full

shaft rotation. This value is

nominally 90

°e or 1/4 cycle.

Output Waveforms

angle which gives rise to one

electrical cycle, and the nominal

angular increment of 1/N of a

revolution.

Pulse Width (P):

The number of

electrical degrees that an output

is high during 1 cycle. This value

is nominally 180

°e or 1/2 cycle.

Pulse Width Error (

∆ P): The

deviation, in electrical degrees, of

the pulse width from its ideal

value of 180

°e.

State Width (S):

The number of

electrical degrees between a

transition in the output of channel

A and the neighboring transition

in the output of channel B. There

are 4 states per cycle, each

nominally 90

°e.

Definitions

Count (N):

The number of bar

and window pairs or counts per

revolution (CPR) of the

codewheel.

One Cycle (C):

360 electrical

degrees (

°e), 1 bar and window

pair.

One Shaft Rotation:

360

mechanical degrees, N cycles.

Position Error (

∆Θ): The

normalized angular difference

between the actual shaft position

and the position indicated by the

encoder cycle count.

Cycle Error (

∆C): An indication

of cycle uniformity. The differ-

ence between an observed shaft

Note:

1. Absolute maximums for HEDS-5140/6140 codewheels only.

Absolute Maximum Ratings

Shaft Axial Play ................................................

± 0.25 mm (± 0.010 in.)

Shaft Eccentricity Plus Radial Play ..................... 0.1 mm (0.004 in.) TIR