Editing Optical mouse (section)

== Modern optical mice ==
{{more citations needed|section|date=January 2023}}
{{cleanup|section|reason=Unclear paragraphs|date=August 2015}}

=== Optical sensor ===
[[File:ST_Microelectronics_OSMLT04_H_mouse_sensor_chip_with_vertical_and_horizontal_illumination.jpg|thumb|Microscope photograph of the IntelliMouse Explorer [[sensor]] silicon [[Die (integrated circuit)|die]]]]
[[File:Opto mouse sensor.jpg|thumb|The optical sensor from a Microsoft Wireless IntelliMouse Explorer (v. 1.0A)]]

Modern surface-independent optical mice work by using an [[optoelectronic]] [[sensor]] (essentially, a tiny low-resolution video camera) to take successive images of the surface on which the mouse operates.  As computing power grew cheaper, it became possible to embed more powerful special-purpose [[image processing|image-processing]] [[integrated circuit|chips]] in the mouse itself. This advance enabled the mouse to detect relative motion on a wide variety of surfaces, translating the movement of the mouse into the movement of the cursor and eliminating the need for a special mouse-pad. A surface-independent coherent light optical mouse design was patented by Stephen B. Jackson at Xerox in 1988.<ref>{{cite patent |country=US |number=4794384 |status=patent}}</ref>

Xerox's inventions were never massively commercially exploited, however, and optical mice would remain elusive in the personal computer market until [[Microsoft]] released the [[IntelliMouse]] with IntelliEye and IntelliMouse Explorer in 1999.<ref name="aiecv" /><ref>{{Cite web |date=1999-04-19 |title=Microsoft Press Release, April 19th 1999 |url=http://www.microsoft.com/presspass/press/1999/apr99/eyepr.mspx |url-status=dead |archive-url=https://web.archive.org/web/20111128233939/http://www.microsoft.com/presspass/press/1999/apr99/eyepr.mspx |archive-date=2011-11-28 |access-date=2011-05-11 |publisher=Microsoft}}</ref> These mice used technology developed by Hewlett-Packard under their [[Agilent Technologies]] subsidiary (see [[#Principle of operation|below]]). These mice worked on almost any surface, and represented a welcome improvement over mechanical mice, which would pick up dirt, track capriciously, invite rough handling, and need to be taken apart and cleaned frequently. Other manufacturers soon followed Microsoft's lead, including Apple for their [[Apple Pro Mouse|Pro Mouse]],<ref name="aiecv">{{Cite book |last=Lyon |first=R.&nbsp;L. |chapter-url=https://books.google.com/books?id=p_GbBQAAQBAJ&dq=%22hewlett+packard%22+%22intellimouse%22+%22agilent%22+%22optical+mouse%22&pg=PA20 |title=Advances in Embedded Computer Vision |date=2014 |publisher=Springer |isbn=9783319093871 |editor-last=Kisačanin |editor-first=Branislav |page=20 |chapter=The Optical Mouse: Early Biomimetic Embedded Vision |editor-last2=Margrit Gelautz |via=Google Books}}</ref> using components manufactured by Agilent (once they spun off from HP), and over the next several years mechanical mice became obsolete.
[[File:S5085 optical mouse IC.jpg|thumb|'''S5085''' optical sensor IC die (CMOS sensor + driver)]]
The technology underlying the modern optical computer mouse is known as [[digital image correlation]], a technology pioneered by the defense industry for tracking military targets.  A simple binary-image version of digital image correlation was used in the 1980 Lyon optical mouse.  Optical mice use image sensors to image naturally occurring texture in materials such as wood, cloth, mouse pads and [[Formica (plastic)|Formica]].  These surfaces, when lit at a grazing angle by a light emitting diode, cast distinct shadows that resemble a hilly terrain lit at sunset.  Images of these surfaces are captured in continuous succession and compared with each other to determine how far the mouse has moved.

=== Principle of operation ===
To understand how [[optical flow]] is used in optical mice, imagine two photographs of the same object except slightly offset from each other.  Place both photographs on a [[light table]] to make them transparent, and slide one across the other until their images line up.  The amount that the edges of one photograph overhang the other represents the offset between the images, and in the case of an optical computer mouse the distance it has moved.

Optical mice capture one thousand successive images or more per second.  Depending on how fast the mouse is moving, each image will be offset from the previous one by a fraction of a pixel or as many as several pixels.  Optical mice mathematically process these images using cross correlation to calculate how much each successive image is offset from the previous one.{{Citation needed|date=November 2022}} The output of the optical sensor is usually delta {{Code|X, Y}} coordinates. Some optical ICs allow to get image data as well. Mice usually embeds some kind of Image Acquisition System and [[Digital signal processor|DSP processors]] for fast data processing.

An optical mouse might use an image sensor having an 18 × 18 pixel array of monochromatic pixels. Its sensor would normally share the same [[Application-specific integrated circuit|ASIC]] as that used for storing and processing the images. One refinement would be accelerating the correlation process by using information from previous motions, and another refinement would be preventing deadbands when moving slowly by adding interpolation or frame-skipping.{{Citation needed|date=November 2022}}

The development of the modern optical mouse at Hewlett-Packard Co. was supported by a succession of related projects during the 1990s at HP Laboratories.  In 1992 William Holland was awarded US Patent 5,089,712 and John Ertel, William Holland, Kent Vincent, Rueiming Jamp, and Richard Baldwin were awarded US Patent 5,149,980 for measuring linear paper advance in a printer by correlating images of paper fibers.  Ross R. Allen, David Beard, Mark T. Smith, and Barclay J. Tullis were awarded US Patents 5,578,813 (1996) and 5,644,139 (1997) for 2-dimensional optical navigational (i.e., position measurement) principles based on detecting and correlating microscopic, inherent features of the surface over which the navigation sensor travelled, and using position measurements of each end of a linear (document) image sensor to reconstruct an image of the document.  This is the freehand scanning concept used in the HP CapShare 920 handheld scanner.  By describing an optical means that explicitly overcame the limitations of wheels, balls, and rollers used in contemporary computer mice, the optical mouse was anticipated. These patents formed the basis for US Patent 5,729,008 (1998) awarded to Travis N. Blalock, Richard A. Baumgartner, Thomas Hornak, Mark T. Smith, and Barclay J. Tullis, where surface feature image sensing, image processing, and image correlation was realized by an integrated circuit to produce a position measurement.  Improved precision of 2D optical navigation, needed for application of optical navigation to precise 2D measurement of media (paper) advance in HP DesignJet large format printers, was further refined in US Patent 6,195,475 awarded in 2001 to [[Raymond Beausoleil|Raymond G. Beausoleil]], Jr., and Ross R. Allen.