This section provides an overview for linear encoders as well as their applications and principles. Also, please take a look at the list of 26 linear encoder manufacturers and their company rankings.
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A linear encoder is a device that uses a sensor to read the linear position of a moving device. In contrast, the type that detects the rotation angle is called a rotary encoder.
There are two types of encoders: an incremental type that outputs the distance traveled according to the amount traveled and an absolute type that outputs the absolute position. Absolute encoders can determine the current position when the power is turned on again, no matter under what conditions the equipment is turned off. Still, they are more complicated and expensive in comparison.
Linear encoders are used in industrial equipment and other devices that require motors, hydraulic pressure, or pneumatic pressure and require multiple high-precision positioning. Rotary encoders are often used with motors, etc. However, the stop position of the motor does not always correspond to the stop position of the equipment due to backlash, twisting, deflection of parts, etc., in the process of converting rotational motion into linear motion. For equipment where these errors cannot be tolerated, linear encoders directly determine the stop position of the equipment.
Another example of use that is relatively familiar is digital calipers. In addition to reliably measuring in digital form, these calipers can be connected to a PC or other device to record measurement results easily and reliably.
A linear encoder consists of two parts: a linear scale with a built-in scale for position detection and a sensor that reads the scale.
There are two detection methods: optical and magnetic.
In the case of the optical method, the scale has a slit or reflector at the scale position, and the position is determined by whether or not light passes through the slit or, in the case of the reflector, whether or not light reflects back.
It uses high precision and high resolution but requires a cover in environments where water, oil, or dust may be generated. The structure is complex and large because the sensor needs to move while covered.
In the case of the magnetic type, the scale is magnetized at the scale position. The position is determined by sensing changes in the magnetic force. Because of its magnetic sensing structure, the scale is resistant to water, oil, and dust, and because of its simple structure, many of them are small in size.
Absolute-type sensors have a specific pattern of slits, reflectors, and magnetic force on the scale side to determine absolute position by combining patterns.
The incremental type generates a pulse signal when it moves a certain distance. Since position misalignment may occur when the encoder is operated continuously, there are methods such as periodically inserting a homing operation.
In recent years, there has been rapid progress in semiconductors, and the semiconductor industry has developed with higher integration, according to Moore's Law. This progress in the semiconductor industry has spilled over into various electronic devices, and electronic control and higher precision are applied to various products. As integration and density increase, so does position detection accuracy in semiconductor manufacturing equipment and machine tools that manufacture mechanical parts with high precision.
Precise position control in semiconductor manufacturing equipment and machine tools requires an actuator to move an object and a detection method to detect the exact position of the actuator. Currently, laser interferometers and encoders are used for precise position detection.
In designing an actuator, it is common to configure an actuator based on linear motion in the three axes (X, Y, and Z) and spatial motion by combining these three axes. Therefore, linear encoders are used for precise linear position detection. Scales and detectors are installed on the moving and fixed parts to precisely detect the distance.
Linear encoders are widely used in precision equipment for machine tools and semiconductor manufacturing because they can accurately measure positions. Still, they are commonly used with resolutions on the micron order or lower.
Therefore, the mounting method and mounting accuracy are essential when designing to maintain that accuracy. The mounting accuracy of linear encoders is described in the instruction manual of each product and manufacturer. The mounting method depends on the structure of the equipment in which the linear encoder will be mounted and must be considered by the designer.
As the accuracy of the linear encoder itself is on the order of microns, for example, mounting accuracy of 1 mm or less is required for the distance between the sensor and the scale, yaw, roll, and pitch, respectively. Depending on the need, it may be necessary to design and manufacture a precision jig or manually adjust the encoder during mounting.
*Including some distributors, etc.
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ONExia Inc is based in Exton, Pennsylvania and is a robotics integrator, custom machine builder, and industrial distributor. ONExia specializing in manual process automation and assists manufacturers of all sizes increase throughput with cutting edge technology. ONExia works with customers to develop turnkey custom machines including 2D & 3D vision system integration, software design & development, and machine safety services. ONExia uses robotics to automate line packaging. ONExia also offers robot palletizers that are compatible with new or existing packaging lines.
Kinequip, Inc. was founded in 1946 in Buffalo, NY as a distributor of industrial parts, accessories, and kits. Today these offerings have grown to include motors, compressors, blower systems, clams, pumps, various fittings, gauges, and sensors, as well as pneumatic and high-pressure devices. Kinequip also serves as a distributor for individual device and parts manufacturers. Kinequip additionally offers custom-designed solutions ranging from R&D to unique components and special-made parts, as well as value added designs on demand.
Pilz is headquartered in Ostfildern, Germany. Pilz designs components, systems, and services to assist industrial plant and machinery customers globally. Customers include many industries such as metals, pharmaceutical, food, presses, and robotics. Pilz serves customers through 4 venues: products and industries, services, support, and training. Products and services include everything from sensor technology and small controllers to robotics to software and operation monitoring. Services include machinery and workplace safety and international compliance. Support is offered 24/7. Training is available through courses and qualification programs.
Pepperl+Fuchs, Inc. was founded in Mannheim, Germany in 1945 developing the forerunner of the proximity switch. Pepperl+Fuchs continues to develop proximity sensors as well as other industrial sensors including ultrasonic sensors, rotary encoders, positioning systems, display and signal processing, vibration monitoring, industrial communication, and signal processing as well as related accessories and software. Explosive protection products include safety barriers, surge protection, wireless solutions, HMI systems, power supplies, electrical explosion protection equipment, level measurement, and related software.
Ranking as of March 2023 GloballyDerivation Method
Derivation MethodThe ranking is calculated based on the click share within the linear encoder page as of March 2023. Click share is defined as the total number of clicks for all companies during the period divided by the number of clicks for each company.
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