A length-measuring device includes a scanning carriage for scanning a measuring graduation that is to be guided longitudinally in the measurement direction on a guide surface. A coupling couples the scanning carriage to a drive dog rigidly in the measurement direction and resiliently transversely to the measurement direction. A first spring is disposed between a connecting element of the coupling and the drive dog and exerts a pressure force on the scanning carriage at a first position so as to press the scanning carriage against the guide surface. A second spring is disposed between the connecting element and the scanning carriage. The second spring is spaced apart from the first spring in the measurement direction and exerts a pressure force on the scanning carriage at a second position spaced apart from the first position in the measurement direction so as to press the scanning carriage against the guide surface.

A linear piezoelectric motor and a slider drive system thereof are disclosed. The linear piezoelectric motor includes a piezoelectric ceramic element and a base structure. The piezoelectric ceramic element includes a first region, a second region and an interval region located between the first and the second region, wherein the first and the second region may be formed by a first and a second power signal supplied by a power supply to form a first and a second standing wave, respectively. The interval region is a quarter wavelengths. The first and the second standing wave have a phase difference so as to form a traveling wave. The base structure disposes the piezoelectric ceramic element and has a pectinate structure to increase the amplitude of the first and the second standing wave, thereby enabling the piezoelectric motor to be driven.

An encoder apparatus comprising a scale and a readhead assembly comprising a scale signal receiver. The scale and the scale signal receiver are located within a protective housing which is configured to protect them from contamination located outside the protective housing and comprises a seal through which the scale signal receiver can be connected to a part outside the protective housing. The arrangement of the scale signal receiver inside the protective housing is independent of the scale and protective housing.

A sealed encoder module for mounting onto a machine so as to measure relative displacement of first and second parts of the machine. The sealed encoder module can comprise, a scale, a readhead comprising a scale signal receiver, and an integral protective housing which encapsulates at least the scale and said scale signal receiver. The sealed encoder module can be configured to determine and output diagnostic information regarding a scale signal detected by the readhead.

A scale and related method for a length-measuring system for recording the absolute values of angles or distances. The scale includes a printed circuit board, at least one track for identifying length information or angle information and a coding for identifying the scale. The coding has at least one coding element comprising at least two electrodes and a conductive connection between the electrodes on an insulator substrate. The electrical connection is configured to be irreversibly destroyed when an electrical current is applied.

A linear rotary encoder includes a pair of rotational surfaces. A contact belt has a first end coupled to a first rotational surface in the pair and a second end coupled to a second rotational surface in the pair. The contact belt is driven to rotate around the pair of rotational surfaces by a driving force applied to media to move the media from the first end toward the second end. An encoding scale is coupled to an inner surface of the contact belt. A reader is positioned to read the encoding scale as the contact belt rotates around the pair of rotational surfaces. The reader generates an output signal indicating a position of the media based on reading of the encoding scale.

There is provided a linear displacement measuring apparatus which notifies a user when being installed defectively. A slider includes a traveling body which travels along a main scale on the main scale, a carriage part mounted on an object, and coupling means which couples the traveling body with the carriage part. The coupling means allows relative displacement between the traveling body and the carriage part and biases the traveling body towards the main scale. The coupling means has a connecting rod arranged so as to couple the traveling body with the carriage part via a ball joint. The slider further has misalignment detecting means which detects that the relative displacement between the traveling body and the carriage part exceeds a prescribed allowable range. The misalignment detecting means is a pair of projecting pieces arranged in a vicinity of the connecting rod so that the displacement of the connecting rod is regulated within a predetermined range.

There is provided a mounting tool, for a linear displacement measuring apparatus, which is capable of reducing thermal stress of a scale housing case and is detachable while having a simple structure.

The mounting tool includes a cylindrical bush inserted into a through hole drilled in the scale housing case, an O-ring interposed between an inside wall of the through hole and the bush, a mounting screw inserted into a cylindrical hole of the bush and screwed into a mounting face, and a plate spring arranged between a head part of the mounting screw and an outside face of the scale housing case, and biasing the scale housing case toward the mounting face.

To provide a linear encoder including a scale unit and a slider that slides along the scale unit, wherein the slider includes a slider enclosure including a slider holding unit, a detection head holding unit mounted inside a scale enclosure of the scale unit, and a pillar extending between the outside and inside of the scale enclosure to connect these two holding units, and a part of the pillar closer to the detection head holding unit and a part of the detection head holding unit closer to the pillar are bored by a thickness larger than a thickness of the pillar.

A double ball-bar measuring system includes a calibration unit, at least two double ball-bars and a measuring module. Among the double ball-bars, at least one is a measuring double ball-bar and at least one is a reference double ball-bar. The measuring double ball-bar is installed on a measurement apparatus to measure or calibrate a target machine. The reference double ball-bar is disposed on the calibration unit to measure thermal errors. When the target machine is driven for measurement or calibration, the geometric and thermal errors of the measuring double ball-bar are compensated so that the measurement apparatus can achieve highly accurate measurement.