Optical mice have a number of advantages over conventional bead mice. By not relying on mechanical parts, the probability of failure is lower, but at the same time, it reduces the ability to repair. We also don’t have to worry about annoying dirt building up on the mouse and for performance they’re much more precise when it comes to capturing gear changes and don’t require use. special rugs.
What is an optical sensor?
In order to understand how mice with optical sensors work, the first thing we will need to know is how these types of sensors work. As for its simplified description, all that an optical sensor does is convert light rays into an electronic signal that a processor can measure. Optical sensors are not only used in mice, for example your smartphone’s automatic brightness system uses one of these sensors to automatically lower the screen brightness.
Optical sensors have many other uses beyond their use in PC mice. Among its utilities are photocopiers and document scanners, as well as for detecting the presence of moving objects. These are used for automatic photography and alarm systems, especially to detect the presence of animals in nature.
But what interests us is how these types of sensors work in the mice that we use daily on our PCs, since since the launch of Microsoft’s Intellimouse in 1999, these mice have supplanted the classic ball mice and have seen appear mouse based on laser lighting, where the first of these in history was the MX 1000 from Logitech.
The optical sensor of PC mice
In the case of optical mice, these do not emit any type of light, so the mouse usually comes with a light emitter, usually an LED light, although it could also be a laser, with which the surface on which it is placed is illuminated, move the mouse. When in the specifications of a mouse, they don’t say that its sensor has a certain amount of IPS, they are actually talking about the amount of frames per second produced by the photodetector.
Said information is processed by a processor which can be digital signal, DSP, or be a fixed function unit. Her task? Compare the images with each other to see if there has been any displacement. For this, we use an internal mesh in which all the “pixels” of the image are aligned and identified. When there has been a shift in the next frame, the DSP knows it by comparing the position of each pixel from one frame to another.
It must be taken into account that knowing the displacement between two points and taking into account the time, the speed of movement of a body and also the acceleration can be known. After the DSP has processed the data, the conclusion of the data is sent to the PC. This is done at very high speed and therefore at a time when the user sees a direct movement correlation between movement with their mouse and the cursor on the screen. Reality? It is an illusion produced by the high frequency at which the optical sensor operates and the images it captures are processed.
LED lighting versus laser lighting
A laser mouse is the same as an optical mouse, the principle of operation is the same, but they differ in the type of light used to illuminate the surface. In the case of LED lighting, this has the problem that it cannot penetrate many surfaces. The results ? If it turns out that you are using the mouse on a highly reflective surface, such as a glass table, then what will happen is that the pattern the optical sensor picks up will be wrong.
This is why mice with an optical sensor that use a laser to illuminate have higher accuracy than those that use LED lighting, although this accuracy can be counterproductive, as they can capture unnecessary overinformation, leading to errors. in its interpretation by part. of the DSP. As a result, movement with the mouse is not interpreted correctly and can lead to errors in programs such as graphic design, where high precision is required with the mouse.
There are therefore situations in which an optical sensor with LED illumination is better than a laser, the cost being the highest of them, but also the fact that a laser is a part much more sensitive to breakage than it is. an LED light. Also, the only handicap is its use on highly reflective surfaces.
Laser or LED, which technology is better?
Faced with this question, each manufacturer will give a different answer, some will tell you that an optical sensor with LED light is much better and others with laser. The former are generally recommended for conventional uses, unless you move the mouse over glass or a highly reflective surface. On the other hand, lasers are typically used in professional gaming mice, and as a result, they tend to be generally much more expensive.
It should be taken into account that an important part of the process is how the DSP built into the mouse interprets the captured images. This is crucial and different brands of mice are developing their own proprietary technologies, based on the use of their own DSPs. After all, the optical sensor photodetector, laser, LED light, and the rest of the components for different types of mice are pretty standard, with DSP being the most unknown and at the same time the most important hardware. of an optical mouse. .