Optical sensor, in particular for a cylinder, and application

#The present invention relates to the technical field of optical sensors, particularly optical position sensors, for example fluid cylinders, such as for hydraulic or pneumatic cylinders.

#For measuring the actual length of fluid cylinders, particularly hydraulic or pneumatic cylinders, there are various technical options available; in particular there are various ways of stroke measurement in a cylinder using sensors, with the sensors being classified as internal sensors and external sensors.

#In case of internal sensors the stroke is measured inside the cylinder. Here, for example magnetostrictive sensors, magnetic field sensors, or in case of larger cylinders also cable sensors are used. The advantage of internal sensors is given in that they are very well protected from external influences; however, the expense for integrating them in the cylinders is high. Additionally, the installation is only possible at a certain minimum size, and the length of the completely retracted cylinder (block length) is increased.

#As already explained above, there are various options to advantageously implement the teaching of the present invention and to further develop it. For this purpose, additional embodiments, features, and advantages of the present invention are explained in greater detail based on the exemplary embodiments illustrated in FIGS. 1A to 3B.

#Shown are:

#FIG. 1A in a schematic illustration of the concept, a first exemplary embodiment for the sensor according to the invention, which operates based on the principle of absolute length measurement of the present invention;

#Identical or similar embodiments, elements, and features are provided with identical reference characters in FIGS. 1A to 4.

#A preferred exemplary embodiment of the present invention is illustrated based on FIG. 1A.

#The sensor S comprises a lighting unit and two camera units, in addition to an integrated or allocated evaluation unit, particularly an evaluation electronic, which may be realized for example via a DSP or CPU. Each of the two camera units, essentially arranged linearly in reference to the longitudinal extension of a piston rod 6, comprises a lens system 1 and a photosensitive sensor element 3 arranged on a circuit board 4, with the lens system 1 and the sensor element 3 being provided in an optic housing 2. Optic housings 2 and circuit boards 4 are in turn arranged in a housing 5. The sensor elements 3 are particularly embodied as CCD-image sensors (CCD: charge-coupled device), which comprise a matrix of light-sensitive elements, such as photodiodes, and which can record a two-dimensional image.