Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-05-05
2001-10-09
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C250S231130, C345S165000
Reexamination Certificate
active
06300620
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to optical sensors for pointing devices, such as mice and trackballs. In particular, it relates to the reduction of the number of components.
Typically, mice and trackballs have a ball which is either rolled across a desktop when a user moves the mouse, or is manipulated with a user's finger for a trackball. This motion is detected in both the x and y directions by the use of two rollers which are biased against the ball inside the device. The rollers are offset from each other at an angle of 90°. Each roller will typically have a shaft connected to an encoder wheel, which is a wheel with a number of slots. A light emitter, such as a light emitting diode (LED) is mounted on one side of each encoder wheel, with one or more photodetectors on the other side. Multiple photodetectors may be used for differential detection. When the encoder wheel turns, light alternately passes through the slots, and is blocked by the encoder wheel, allowing a determination of the amount of movement of the ball in the x or y direction.
Newer mice and track balls will sometimes include a separate roller wheel which the user can manipulate for scrolling. Such a roller wheel is typically also connected to a separate encoder wheel, which also has an emitter and a detector on either side for determining its movement.
Another typical input for mice and trackballs is one or more buttons to indicate a clicking function. The buttons are typically spring biased to allow the user to depress them, and then have them pop back up. The buttons will typically depress a microswitch mounted beneath the button to provide an input signal. Each button typically has its own microswitch.
One of the challenges in the design of such pointing devices is the reduction of costs and reductions in size, or fitting additional functionality in the same size device. One obvious way to reduce costs is to reduce the number of components required to build the mouse or trackball or other pointing device.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for eliminating at least one light emitter and light detector in a mouse design. This is done by using two conical shaped encoder wheels positioned so that they are almost touching each other. A single light emitter then is used to shine light at the junction, so that it passes through both cones. On the opposite side is a single chip, with two photodetectors integrated on each side. The chip is positioned so that light passing through the first conical encoder impinges on the first photodetector, while light passing through the second conical encoder impinges on the second photodetector. Thus, the two photodetectors can be integrated on a single chip, saving a separate photodetector chip. In addition, only a single LED is required.
In a preferred embodiment, encoder wheels are connected to rollers which contact the ball at 90°. The encoders are conically shaped with a cone angle of 45°. The semiconductor chip with the photosensors is mounted in the vertical plane tangent to both conical shaped encoders. The encoders alternately block and let light pass through as they rotate with their respective roller.
In an alternate embodiment, a controller or application specific integrated circuit (ASIC) for the pointing device can also be integrated on the same semiconductor chip as the photosensor. This further reduces the part count by combining these two chips into one.
In an additional embodiment, a light pipe can be used to direct light to a third sensor on the semiconductor chip, thus eliminating another photosensor chip. The third sensor could be used to detect light passing through an encoder wheel connected to a roller for scrolling. Alternately, light could be used to detect the depression of a button, rather than the microswitch. Thus, one or more light pipes can connect to multiple sensors on the same chip.
For further understanding of the nature and advantages of the invention, reference should be made to the following description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5434594 (1995-07-01), Martinelli et al.
patent: 5559534 (1996-09-01), Lin
Bidiville Marc
Nicoud Jean-Daniel
Sommer Rene
Lee John R.
Logitech Inc.
Pyo Kevin
Townsend & Townsend & Crew LLP
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