Optical Encoders

Optical encoders are a very wide spectrum of encoders which are often referred to as optical rotary encoders. This type of device can convert angular positions or motions of the objects such as shafts or axles into analog or digital signal, rendering the precision positions. 

The absolute optical encoders and incremental encoders are two different types under this inventory. For the case of absolute encoders, this device would maintain the position information when the power is removed from the encoder, while the incremental encoder would immediately report the changes in positions, but the incremental version would not keep track of the absolute position. 
 

Essential Differentiations: Need to be Homed or not

Due to the fact that the position of the encoder is always available on applying power, the relation between then encoder values and the real-time position of the manage equipment is settled at the assembly, and the system itself does not need to return to the calibration point to keep up with the position accuracy and the precision values.

In the absolute encoding method, there are multiple code rings which are designed with many binary types of weighting, and this offers a data word. The existence of data word indicates the absolute positions of the encoder within a revolution. On the other hand, a multi turn basis absolute rotary encoder involves additional code wheels and the toothed wheel units. 

Moreover, a high resolution wheel inspects the fractional rotation, and lower resolution geared code wheels would record the number of the whole revolutions of the shafts. On the other hand, incremental encoders would report the changing state of the position immediately as this is the essential nature in some application cases. Since incremental optical encoders would not report the track of absolute positions, and the mechanical system supervised by this type of optical encoders would have to be recalibrated by homing, or say, homed. The home of this encoder means to move to a fixed reference point so it would initialize the absolute position methods. 

The need to be homed is critical to distinguish incremental from absolute optical encoders. By this feature the two are divided. The use of this technology can be applied to many industrial products, such as industrial controls, robotic items, lenses of photographic technology, computer mice as well as trackballs, controlled pressure RHEOMETERS, and some rotating radar objects. 
 

Optical Encoders and Computer Mouse

It is about the 1990s that ordinary people and users started to use the optical computer mice when they were using their computers. Before the optical computer mice were used, personal computer users used mechanical mice based on the very model invented in the late 1960s. For the mechanical based ball mice, there are two freely rotating rollers which are located ninety degrees apart from each other. Regarding the rollers, one is designed to detect the forward and backward action of the mechanical mice, and the other rollers are designed to detect the left and right actions. 

This type of mice is easy to wear out physically as the physical condition of the rollers and the balls are susceptible to the mats and table circumstances. Compared to the mechanical mice, today’s optical mice work by utilizing the optoelectronic sensing objects to take continuous images of the surface unto which the optical mouse is used. So based on these physical limitations, mechanical mice wear out easily and cause many maintenance problems, so with the invention of the optical encoder technology in the utilization application in personal computer application, those optical mice today can be used for a longer period of time compared to the former mechanical mouse designs. Furthermore, with the growth of the computing technology, now it is getting more and easier to embed more powerful image processing chips in the mice to enhance their performances for all kinds of mouse usages, delivering the convenient and resilient operation. 

In a sense, the idea of optical encoders share some common features with the dial caliper in a way that dial calipers are often used in precision inspection, such as using diameter values as the primary means for testing accuracy because of its fast and precise capability of the inspection capacity. A dial scale is a compact device that relies on visual aid to take accurate measurements of checked value between the two graduation markings on a linear scale volume by using mechanical interpolation. These features, though not identical, share some similarities with the optical encoders. 

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