Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-12-08
2001-04-17
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C345S165000, C345S166000, C345S167000
Reexamination Certificate
active
06218659
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to dual layer optical balls for use with pointing devices for cursors on displays for personal computers, workstations and other computing devices having cursor control devices, and more particularly relates to optical devices and methods for translating rotation of a patterned ball over optical elements or movement of an optical device over a patterned surface into digital signals representative of such movement.
BACKGROUND OF THE INVENTION
Pointing devices, such as mice and trackballs are well known peripherals for personal computers and workstations. Such pointing devices allow rapid relocation of the cursor on a display screen, and are useful in many text, database and graphical programs. Perhaps the most common form of pointing device is the electronic mouse; the second most common may well be the trackball.
With a mouse, the user controls the cursor by moving the mouse over a reference surface; the cursor moves a direction and distance proportional to the movement of the mouse. Although some electronic mice use reflectance of light over a reference pad, and others use a mechanical approach, most prior art mice use a ball which is on the underside of the mouse and rolls over the reference surface (such as a desktop) when the mouse is moved. In such a prior art device, the ball contacts a pair of shaft encoders and the rotation of the ball rotates the shaft encoders, which historically includes an encoding wheel having a plurality of slits therein. A light source, often an LED, is positioned on one side of the encoding wheel, while a photosensor, such as a phototransistor, is positioned substantially opposite the light source. Rotation of the encoding wheel therebetween causes a series of light pulses to be received by the photosensor, by which the rotational movement of the ball can be converted to a digital representation useable to move the cursor.
The optomechanical operation of a trackball is similar, although many structural differences exist. In a trackball, the device remains stationary while the user rotates the ball with the thumb, fingers or palm of the hand; one ergonomic trackball is shown in U.S. Pat. No. 5.122,654, assigned to the assignee of the present invention. As with the mouse. the ball in a conventional trackball typically engages a pair of shaft encoders having encoding wheels thereon. Associated with the encoding wheels are tight sources and photosensors, which generate pulses when the movement of the ball causes rotation of the shaft encoders. One prior art trackball using this approach is shown in U.S. Pat. No. 5,008,528.
Although such a prior art approach has worked well for some time, with high quality mice and trackballs providing years of trouble-free use, the mechanical elements of such pointing devices necessarily limit the useful life of the device.
Optical mice which illuminate a reference pad, while having few or no mechanical parts, have historically been limited due to the need for the reference pad to have a regular pattern, as well as many other limitations.
Additionally, in conventional electronic mice, a quadrature signal representative of the movement of the mouse is generated by the use of two pairs of LED's and photodetectors. However, the quality of the quadrature signal has often varied with the matching of the sensitivity of the photosensor to the light output of the LED. In many instances, this has required the expensive process of matching LED's and photodetectors prior to assembly. In addition, varying light outputs from the LED can create poor focus of light onto the sensor, and extreme sensitivity of photosensor output to the distance between the LED, the encoding wheel, and the photosensor.
There has therefore been a need for a photosensor which does not require matching to a particular LED or batch of LED's, while at the same time providing good response over varying LED-to-sensor distances.
In addition, many prior art mice involve the use of a mask in combination with an encoder wheel to properly distinguish rotation of the encoder wheel. Because such masks and encoder wheels are typically constructed of injection molded plastic, tolerances cannot be controlled to the precision of most semiconductor devices. This has led, effectively, to a mechanical upper limit imposed on the accuracy of the conventional optomechanical mouse, despite the fact that the forward path of software using such mice calls for the availability of ever-increasing resolution. There has therefore been a need for a cursor control device for which accuracy is not limited by the historical tolerances of injection molding.
SUMMARY OF THE INVENTION
The present invention substantially overcomes the foregoing limitations of the prior art by providing an optical sensing system which eliminates entirely the use of shaft encoders, the encoding wheels associated with shaft encoders, masks or other mechanical elements normally associated with optomechanical pointing devices. The present invention can be implemented with either a mouse or a trackball, although the exemplary embodiments described hereinafter will discuss primarily trackball implementations. In addition, while most embodiments require a patterned ball, some embodiments of the present invention do not require any ball at all.
For those embodiments which use a ball, the present invention employs a ball having a pattern of spots (which are typically but not necessarily irregular in location and may be randomly sized within a suitable range) in a color which contrasts with the background color, such as black spots on an otherwise white ball. One or more light sources, typically LED's, illuminate a portion of the ball and a portion of that light illuminates a sensor array comprising a plurality of individual sensor elements to create an image of a portion of the ball. An optical element such as a lens or diffractive optical element may be provided to focus the image of the ball on the array. The signals generated by the array are then acted upon by logic and analog circuits, for example employing a biologically inspired VLSI circuit, such that the movement of the ball is converted into X and Y components for movement of the cursor on the video display. Except for the mechanical aspects of the ball itself (and in some instances the bearings on which the ball is supported), the electronic trackball of the present invention is entirely optical: when the ball is included, the trackball of the present invention may reasonably be thought of as an optomechanical pointing device although it has no mechanical moving parts other than the ball. It will be apparent that the techniques used herein may readily be adapted to other types of pointing devices, particularly electronic mice.
It is an object of the present invention to utilize a dual-layer optical ball for use in a cursor control pointing device. The ball is illuminated by a light source that emits light signals at, at least, a first wavelength, the ball having an inner layer surface that is capable of diffusing a light signal and an outer layer having a substantially smooth surface that surrounds the inner layer. The outer layer is substantially transparent to light at the first frequency. The inner layer diffuses the light signals at different intensities depending upon an the area of the inner surface that is illuminated.
Another object of the present invention is to provide a pointing device in which light illuminating a surface is directed to a sensor through a mirror and lens combination.
It is yet another object of the present invention to provide an electronic pointing device employing a random pattern of randomly sized and shaped spots on a ball in combination with an optical array to provide signals for generating cursor control signals.
It is a still further object of the present invention to provide an electronic pointing device using a light source in combination with an optical element and a photosensitive array to provide signals for generating cursor control signal
Arreguit Javier
Bauduin Francois
Bidiville Marc
Buczek Harthmuth
O'Keeffe Denis
Fenwick & West LLP
Lee John R.
Logitech Inc.
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