Stegmann Encoder

Encoder Solutions & Technical Innovations

Encoders

STEGMANN

SICK|STEGMANN products are designed and developed using the most modern methods to ensure performance targets are met. Before and during manufacturing, they are subjected to the most stringent quality controls, using state-ofthe- art techniques, and high-precision measuring equipment. SICK|STEGMANN manufacturing plants are ISO 9001:2000 certified, ensuring that customer expectations are met in quotation, order entry, engineering, manufacturing, and after-sale service.

STEGMANN Absolute Encoders

Use absolute encoders when position data must be retained after loss of power. Examples include robotics, lead/ball screws, overhead cranes, and rack and pinion applications.

Basic Operation of Optical Rotary Absolute Encoders
As with incremental encoders, absolute optical rotary encoders use a rotating disk to interrupt the light path to a photodetector, which produces an output signal. However, absolute encoders read uniquely coded tracks to generate position information. No two adjacent positions are alike. Therefore, absolute encoders do not lose position data when power is lost. True position is available as soon as power is restored.

Conventional Optical Absolute Encoder Disks A conventional absolute encoder disk features a series of concentric tracks, each consisting of a pattern of transparent and opaque segments. These independent tracks provide a unique combination of absolute values for each resolvable position. One track is needed for each “bit” of position information that is

output as either a serial or parallel data “word.” The preferred code format is Gray Code, in which only one bit of information changes between adjacent positions on the disk. This limits the position error from the track sensors to plus or minus one count. Other available codes, such as Natural Binary or Binary Coded Decimal (BCD), may have several bits change between adjacent positions.

Magnetic Absolute Encoders Many applications require resistance to extremely high shock and vibration, wide temperature variations, or high humidity with condensation. SICK|STEGMANN magnetic absolute encoders meet these unique challenges.

Magnetic field strength of a proprietary 32-pole magnetic ring is measured using two strategically spaced magneto-resistors that pick up variation of the magnetic field intensity along the circumference of the ring. The resulting 32 sine/cosine signals per turn (5-bit) are then enhanced by 8-bit interpolation. A single north

south pole magnet, read by a Hall effect sensor, is used to assign absolute values to individual sine/cosine cycles. Thus, the 32-pole magnetic ring is calibrated for a 13-bit single-turn absolute position feedback. Additional software is used to compensate for temperature variation and resulting differential thermal expansion to insure data integrity.

Electronic Zero Position Teach With all SICK|STEGMANN absolute encoders, the zero position is electronically assigned by the user to the current mechanical position by activation of a pushbutton or set line. No mechanical detachment or rotation of the encoder is necessary.

IDEA AND INNOVATION

STEGMANN Conventional Encoders

innovative engineering, easy operation and optimised functional dependability.

STEGMANN Linear Encoders and Wire Draw Systems

Use linear encoders to measure incremental or absolute position along any axis.

SICK|STEGMANN linear encoders can be used in applications up to 1.7 kilometers long!

L 230 Magnetic (Lincoder®)

The Lincoder® system supplied by SICK|STEGMANN consists of a magnetic tape and sensor head. The magnetic tape provides the scale for measuring systems up to 40 meters long. The absolute information is magnetized onto the tape in a 12-bit sequential code. This position information is enhanced by interpolation of sine/cosine signals provided by an additional incremental track that is magnetized on the tape. The magnetic tape is laminated onto a ferromagnetic steel strip, which is used both as a magnetic return path and a dimensionally stable mounting aid. The magnetic tape is supplied with an adhesive back for mounting by the user.

A non-contact magnetic sensor with integrated electronics is mounted to the apparatus whose position is to be measured. As the sensor moves over the measuring tape, its position is output with a resolution as low as 1 μm over a 16 meter range, or 10 μm over a 40 meter range. Position data is output via real-time compensated SSI (Synchronous Serial Interface), HIPERFACE®, or RS 485. The Lincoder is also programmable via RS 485, and a number of parameters such as offset, resolution and start points can be configured by the user.

KH 53 (Pomux®) and Advanced KH 53

Long Distance Linear Encoders

This style of encoder is unique to SICK|STEGMANN and allows absolute measurement of up to 1.7 kilometers! The KH 53 consists of two basic components: Omega Profile sections and the sensor head. Each Omega Profile section contains a number of powerful permanent magnets. The separation between each magnet is unique and never repeated. These unique separations build up a code over the complete measurement path. In a working system, several Omega Profile sections are placed end to end along the complete measurement path. The total length of the system determines the number of profiles required. Each profile section is labeled with an identification number indicating the order in which the sections should be mounted.

The sensor head moves over the Omega Profile sections without contact, and produces absolute positional data. The KH 53 allows a generous vertical tolerance of ±10 mm around a 25 mm nominal value, and a horizontal tolerance of ±10 mm around the centerline. The output is available in SSI, and Profibus. Other networks can be realized using commercially available I/O modules.

In addition, this modular system offers several benefits to the user. If the measurement length of the system needs to increase in the future, the user simply needs to mount the extra profiles required. If the Omega Profile become damaged, only the damaged sections need to be replaced.

The Advanced KH 53 has 54 m or 548 m measuring lengths, a positional/mounting tolerance to ±20 mm, and an operating temperature of -30 to 70°C. The Advanced KH 53 has the added advantage of requiring less installation time than the standard KH 53.