Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
1998-03-13
2001-05-01
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S2140RC, C250S221000, C250S231130, C345S158000
Reexamination Certificate
active
06225617
ABSTRACT:
INCORPORATION BY REFERENCE
Incorporated herein by reference is the entire disclosure of U.S. patent application Ser. No. 08/424,125, filed Apr. 19, 1995 now U.S. Pat. No. 5,703,356 and assigned to Logitech, Inc., the assignee of the present invention.
FIELD OF THE INVENTION
The present invention relates to optical pointing devices for use with personal computers, workstations and other computing devices, and more particularly relates to optical pointing devices having no mechanically moving parts and which operate without the need for a specially patterned surface.
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.
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.
While optical mice in the prior art have typically required a reference pad, two methods are known in the general optical art for detecting movement of a scattering surface illuminated by coherent illumination. The first such approach employs illumination of the surface with two light sources and using a single detector; the second includes illumination with only a single beam but using a grating filter in front of a single detector. In both these cases, forward and backward movement cannot be distinguished, in what is referred to as sign ambiguity. Likewise, in both case the detection is sensitive to one direction of movement in the plane. Further, in the case of the first prior art approach, the two illuminating beams have to be rotated to be sensitive to another direction of movement; that is, for each direction of movement an independent detection system of illuminating beams and detector has to be used. In the case of the second prior art approach, the grating filter in front of the detector has to be rotated to be sensitive to another direction of movement.
There has therefore been a need for a device which includes a detection system which is sensitive to different directions of movement without alteration of the detection system.
SUMMARY OF THE INVENTION
The present invention overcomes substantially all of the foregoing limitations of the prior art, and provides an improved method and apparatus for optical detection of motion of a detector relative to an irregularly speckled or patterned surface, such as the surface of a common office desk. The desk surface has no special characteristics except that it produces a sufficient amount of diffusely scattered light in response to coherent illumination. In particular, when illuminated by coherent light, for example a laser diode, the illuminated surface has a granular appearance which appears essentially as randomly distributed light and dark speckles. A specially configured detector is combined with novel signal processing techniques to decode bidirectional movement of the speckle pattern. Alternatively, the specially configured detector of the present invention can be combined with a printed pattern on a pad or ball in order to generate the speckles or dots without the requirement for a coherent light source—i.e., a simple diode could be used.
In particular, the detection system of the present invention produces sinusoidal signals in quadrature for forward-backward detection using specially configured photodetectors. The detection system is sensitive to different directions of movement by the use of differently oriented detectors which use the same coherent illumination of the surface. More specifically, a first significant aspect of the invention is a quadruple comb array of photodetectors which senses a component (either x or y) of the movement and produces quasi-sinusoidal quadrature signals. The sinusoidal properties of the signals produced by the photodectors are obtained through optical matching by which the optical system is matched to the period of the photodetector array. Movement of the detector relative to the surface is then detected by a bidirectional counter in a manner similar to a rotational encoder. By combining a plurality of such quadrature encoders at different angles, motion in both the x and y directions can be detected. A microprocessor can be used to combine the signals from the various detectors.
It is therefore one object of the present invention to provide a pointing device which optically detects movement relative to a conventional speckled or patterned surface such as the surface of a desk.
It is another object of the present invention to provide a comb photodetector which is capable of generating quasi-quadrature signals in response to relative motion between the array and a surface capable of diffusely scattering light.
It is a further object of the present invention to provide a pointing device which uses one or more comb photodetectors to detect motion of the pointing device relative to a surface capable of diffusely scattering light.
It is a still further object of the present invention to provide a pointing device which uses a comb photodetector together with a non-coherent light source and a patterned surface to detect relative motion between the photodetector and the patterned surface.
These and other objects of the present invention may be better appreciated from the following Detailed Description of the Invention, taken in combination with the accompanying Figures.
REFERENCES:
patent: 4546347 (1985-10-01), Kirsch
patent: 4720631 (1988-01-01), Lapeyre
patent: 4751380 (1988-06-01), Victor et al.
patent: 4794384 (1988-12-01), Jackson
patent: 4799055 (1989-01-01), Nestler et al.
patent: 4920260 (1990-04-01), Victor et al.
patent: 5015070 (1991-05-01), Montgomery et al.
patent: 5288993 (1994-02-01), Bidiville et al.
patent: 5703356 (1997-12-01), Bidiville et al.
patent: 5729009 (1998-03-01), Dändliker et al.
patent: 6031218 (2000-02-01), Piot et al.
patent: 0 420 172 A1 (1994-04-01), None
patent: 0 614 086 A1 (1994-09-01), None
Anonymous, “Bucket Brigade Charge Packet Diverter. Jan. 1976”, IBM Technical Disclosure Bulletin; vol 18, No. 8, Jan. 1, 1976.
Bidiville Marc
Dandliker Rene
Fenwick & West LLP
Lee John R.
Logitech Inc.
LandOfFree
Method for generating quasi-sinusoidal signals does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for generating quasi-sinusoidal signals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for generating quasi-sinusoidal signals will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2527220