Benefits of an Optical Encoder

The optical zoom function on cell phone cameras avoids the degradation in top quality brought on by digital zoom, but existing implementations are inclined to be noisy, bulky, and power hungry.



Introduction



A wide selection of commercial applications use cameras with a zooming mechanism. Maybe probably the most ubiquitous application is definitely the camera phone. Essential design criteria for camera zooming consist of low-power consumption and, not surprisingly, space constraints. This short article describes an optical encoder technologies that offers a brand new method to camera zooming designs to meet these challenges. Get far more info about optical shaft encoder



Optical and digital zoom



Camera phones may have an optical zoom, a digital zoom, or each. An optical zoom changes the effective focal length from the camera lens such that the original image is magnified and can be captured by the CCD or CMOS image sensor. With greater magnification, the light is spread across the complete image sensor and all the pixels is often used. An optical zoom may be interpreted as a true zoom that can enhance the high-quality of photographs captured.



Digital zoom, on the other hand, can be a bit diverse. In this case, a software algorithm is applied as opposed to a hardware movement (i.e., adjustments in lens positioning) to magnify the image. Such magnification involves only a certain portion in the captured image. That is known as the interpolation strategy. Using such a strategy, or algorithm, calls for facts to become added as a way to enlarge the corresponding image portion. It might appear that the captured image is getting magnified. However, only a specific portion with the real image data is being utilized and the rest of the image is coming in the interpolation outputs.



One thing worth mentioning is the fact that the higher the digital zoom, the smaller sized the portion of real information that may be taken. Thus, quite a few in the initially captured pieces of facts on the image sensor might be discarded and more interpolated image data will likely be incorporated in the resultant image.



As a result, optical zooming is definitely an significant mechanism in figuring out the true zooming power of a camera phone with no losing any image data. Accurate lens positioning control in optical zoom is critical to making sure top quality in an enlarged image. Figure 1 illustrates a standard instance with the zooming mechanism from a camera module inside a camera phone. Lenses are aligned such that an image might be focused onto the image sensor. The zooming mechanism involves synchronous movement of two or additional lenses. By varying the distance involving the lenses, the actual helpful focal length with the camera lens adjustments accordingly. Therefore, a magnified image would be captured by an image sensor.



To simplify the wiring process, encoders are mounted around the camera module shell and remain inside a fixed position. The moving portion is the codestrip, which acts because the translator for the lens' linear movement. Casting the window and bar image back for the encoder gives feedback on all the essential information and facts for prompt and correct lens positioning. With a traditional zooming mechanism, a mixture of mechanical cam and gearing is actually a common method for lens position control. Having said that, such an method will endure unavoidable put on and tear problems, along with the accuracy of lens positioning will degrade over time and straight influence towards the excellent of zoomed images.



An AEDR-8400 encoder Technologies might help to resolve these zooming difficulties. The feedback from the encoder provides vital information and facts for real-time calibration whenever there is any back-lashing from gears and mechanical cams. This can support assure precise and correct lens positioning. In addition, in some customized camera module designs, removing the mechanical cam is possible (see Figure 2).



Incorporating the AEDR-8400 encoder into a piezo-actuator camera module, for instance, can essentially get rid of the use of mechanical cams. And, simply because there is no mechanical cam involvement, there is certainly no fixed zooming position and the new camera module system can utilize a continuous zooming function (see Figure 3).



In terms of power consumption, piezo-actuator systems are likely to consume less power in comparison with voice coil and servo solutions. Also, a piezo-actuator solution could assist maintain the noise and vibration level to a minimum, which a stepper motor or voice coil solution can't accomplish.



The reflected pictures of the window and bar are focused around the photodiodes. As the codestrip moves, an alternating pattern of light and shadow cast by the window and bar, respectively, falls upon the photodiodes. The detector IC converts this pattern into digital, TTL-compatible outputs representing the codestrip linear motion and hence, the lens' movements. An important parameter is resolution, that is defined as the density of window/bar inside a unit distance and is commonly defined as lines per inch or lines per millimeter. Higher resolution signifies finer control in the linear motion.



The AEDR-8400 encoder is made so that the LED and detector IC from the encoder should really be placed parallel towards the window/bar orientation. As such, the encoder is robust against radial play. This idea is illustrated in Figure 5.



The all round camera module design is usually shrunk in comparison with a stepper motor solution or possibly a voice coil solution. The motor size is comparable to the piezo-actuator. On the other hand, the removal of mechanical cams and gearing enables the general camera module dimension to become decreased further to meet existing industry demands.