The history of the computer mouse dates back to December 9, 1968, when it was presented at an exhibition of interactive devices in California. The patent for this gadget was received by Douglas Engelbart 2 years later. The first computer, which included a mouse, was a mini-computer Xerox 8010 Star Information System, introduced in 1981. The Xerox mouse had three buttons and cost $ 400, which is equivalent to the current $ 1000. In 1983, Apple released its own one-button mouse for Lisa computer, the cost of which was reduced by 16 times. The computer mouse has gained wide popularity thanks to use in computers Macintosh. How does a modern computer mouse work? This is in today's issue.
Modern mice come in two types – optical and laser. Regardless of the type, the mouse perceives its movement in the working plane (for example, on a portion of the table surface) and transmits this information to the computer. The program running on the computer, in response to moving the mouse, produces on the screen an action corresponding to the direction and distance of this movement.
In modern optical mice, the so-called optical correlation technology is used. Using a light-emitting diode and a system of light focussing it under the mouse, the surface area is highlighted. Reflected from this surface, light is collected by another lens and falls on the receiving sensor chip – image processor. It, in turn, takes pictures of the surface under the mouse at a high frequency (usually more than 1 kHz) and processes them, incrementally comparing the images. Based on the analysis of successive images, which represent a square matrix of pixels of different brightness, the integrated processor calculates the resultant indicators by determining the direction of movement of the mouse.
The surface on which the mouse moves is usually microrough. Lighting a bright LED, installed at a small angle to the surface, microroughness casts shadows, which are fixed by the sensor. Optical mice usually use red LEDs because of their low cost. In addition, silicon photodetectors are more sensitive to red color. The lack of optical mice is an increased power consumption compared to laser devices.
In laser mice, not an LED is used to illuminate the surface, but an infrared laser diode that illuminates the surface. Because of coherence (that is, consistency) of laser radiation with focusing on the working surface, the latter is much more accurate. In addition, laser mice require much smaller microroughness than required for an optical mouse.
The laser mouse was first released in 1998, being produced by Sun Microsystems. However, at that time it was not widely spread. Unlike an optical mouse, the laser mouse is capable of operating on mirror and transparent surfaces, such as glass, which is a significant advantage.