German SPM SPA sensors, SPM SPA models, SPM SPA prices

SPM SPA sensors are devices that measure the operating speed of an object and convert it into an output signal. Speed sensors include linear speed sensors and rotational speed sensors. With technological advancements, traditional measurement equipment can no longer meet current demands and is gradually being phased out, while laser speed sensors are now widely used. They play a significant role in product manufacturing by enabling automated and intelligent measurement control through connection to computers. This represents the integration of modern measurement technology with computer technology.

SPM SPA sensor structure

It consists of two parts: the scale grating and the grating readhead. The figure on the right shows the structure of a grating ruler. The key component of the grating detection device is the grating readhead, which comprises a light source, condensing lens, index grating, photoelectric elements, and adjustment mechanisms. Grating readheads come in many structural forms, classified based on their design and application into direct-reception readheads (also known as silicon photovoltaic cell readheads), mirror-image readheads, beam-splitter readheads, and metal grating reflective readheads.

SPM SPA sensor principle

The essence of a grating displacement sensor is measuring position using the grating pitch as a standard scale. High-resolution grating rulers are generally expensive and difficult to manufacture. To improve system resolution, Moiré fringes must be subdivided; grating ruler sensor systems mostly use electronic subdivision methods. When two gratings overlap at a slight angle, Moiré fringes are generated in a direction roughly perpendicular to the grating lines. As the grating moves, the Moiré fringes move up and down accordingly. This converts the measurement of grating pitch into the measurement of the number of Moiré fringes. Within the width of one Moiré fringe, placing 4 photoelectric devices at specific intervals enables electronic subdivision and direction determination. For example, for a grating ruler with 50 line pairs per mm, the grating pitch is 0.02mm. With four-fold subdivision, counting pulses with a resolution of 5μm can be obtained, achieving high precision for general industrial measurement and control. Since displacement is a vector, both its magnitude and direction must be detected, requiring at least two photoelectric signals with different phases. To eliminate common-mode interference, DC components, and even harmonics, differential amplifiers composed of low-drift operational amplifiers are typically used. The 4 photoelectric signals obtained from 4 photosensitive devices are sent to the inputs of 2 differential amplifiers. The two signals output from the differential amplifiers have a phase difference of π/2. To obtain direction determination and counting pulses, these two signals must first be shaped into square waves with a duty cycle of 1:1. Then, by comparing the phases of the square waves, the movement direction of the grating ruler can be determined. By counting the square wave pulses, the displacement and speed of the grating ruler can be obtained.

SPM SPA sensor usage precautions

Power off before plugging or unplugging the connector between the linear scale sensor and the digital readout. Install an external protective cover whenever possible, promptly remove chips and oil that splash onto the scale, and strictly prevent any foreign matter from entering the housing of the linear scale sensor. Regularly check whether the mounting and connection screws are loose. To extend the service life of the dust-proof sealing strip, apply a thin, even layer of silicone oil to the sealing strip; take care not to let it splash onto the glass grating etched surface. To ensure reliable operation of the linear scale sensor, periodically clean and wipe the linear scale surface and the index grating surface with an ethanol mixture (50%), keeping the glass linear scale surface clean. The linear scale sensor must not be subjected to severe vibration or impact, as this may damage the linear scale; if the linear scale breaks, the sensor will fail. Do not disassemble the linear scale sensor yourself, and never arbitrarily change the relative spacing between the main scale and the secondary scale; doing so may degrade the sensor's accuracy and may cause relative friction between the main and secondary scales, damaging the chrome layer and thus the grating lines, resulting in scrapping of the linear scale. Prevent oil contamination and water from polluting the linear scale surface, as this can disrupt the distribution of the grating lines and cause measurement errors. Avoid operating the linear scale sensor in environments with severe corrosive effects, to prevent corrosion of the chrome layer and the scale surface, which would compromise the quality of the linear scale.

Weidou Intelligent Technology specializes in selling German SPM SPA sensors, SPM SPA proximity sensors, SPM SPA distance sensors, SPM SPA vision sensors, SPM SPA displacement sensors, SPM SPA load cells, SPM SPA speed sensors, SPM SPA photoelectric sensors, SPM SPA position sensors, SPM SPA angle sensors, SPM SPA tactile sensors, SPM SPA temperature sensors, SPM SPA pressure sensors, SPM SPA flow sensors, SPM SPA level sensors, SPM SPA motion sensors, and SPM SPA process sensors. All products are original imports from Germany. Customers are welcome to inquire and place orders.