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Circular touch sensorCircular touch sensor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060227117, Circular touch sensor. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] This disclosure relates to touch sensors, and particularly circular touch sensors. BACKGROUND [0002] Touch sensors are used in many electronic and computing devices. Many laptops, for example, are equipped with a rectangular touch sensor that functions like a computer mouse to control pointer positioning on a screen and permit entry of commands. The touch sensor detects the user's touch and generates signals representing a location of contact on the sensor. [0003] FIG. 1 shows a conventional linear touch sensor 100. For discussion purposes, the sensor 100 is illustrated with four rectangular sensor pads 102(1), 102(2), 102(3), and 102(4) that are linearly aligned. This arrangement allows detection of a user's touch within four discrete zones 1-4 that correspond with the four sensor pads 102(1)-102(4). [0004] To increase precision, additional detection zones may be created by changing the shape of the sensor pads. FIG. 2 shows another conventional linear touch sensor 200 having five discrete sensor pads 202(1)-202(5), where each sensor pad has a non-rectangular shape. Edges between adjacent sensor pads are discontinuous or jagged. This shape allows adjoining sensor pads to interlace with one another to define additional detection zones, so that there are more zones than sensor pads. In this example, there are nine detection zones 1-9 for five sensor pads. With this arrangement, a single touch in zone 2 is detected by adjacent sensor pads 202(1) and 202(2), whereas a touch in zone 1 is detected solely by the top sensor pad 202(1). [0005] Many devices today use non-rectangular touch sensors. For instance, some popular audio devices (e.g., MP3 players) employ circular touch sensors. These sensors have traditionally followed the same design as linear sensors, with multiple discrete sensor pads (e.g., 12-16 sensors) aligned side-by-side. FIG. 3 shows a conventional circular sensor 300 having sixteen discrete sensor pads 302 extending radially outward from the center. To increase precision, the edges between the sensor pads may be made jagged. FIG. 4 shows one example circular sensor 400 having multiple sensor pads 402 with jagged edges. Sixteen pads 402 are shown, but there may be fewer (e.g., 12). [0006] These conventional sensors detect presence or absence of a finger on each sensor pad. Past solutions to increase precision have been to increase the number of sensor pads or make the edges jagged to define extra detection zones. However, larger numbers of sensor pads requires more expensive and complex interfaces to convert the detection signals to a smaller number of output pins on circuit chips. Moreover, even as the number of sensor pads increase, the sensors still detect only a finite number of contact positions. [0007] In addition to precision, manufacturing cost is another important consideration for designers of touch sensors. These designers continually look for ways to reduce cost. Conventional circular touch sensors employ anywhere from 12 to 16 sensors, thereby increasing component costs. [0008] Accordingly, there remains a need for an improved circular touch sensor that is inexpensive to produce, yet provides high accuracy and precision similar to that of conventional 16-pad sensors. SUMMARY [0009] A circular touch sensor has three or more sensors arranged in an iris pattern. Each pad is defined by continuous edges that spiral outward about a center point. The unique geometric shape allows measurement of relative amounts of contact on adjoining sensors. In one implementation, the sensors measure relative capacitance of two or more sensors, thereby enabling high precision identification of the point of contact. With as few as three pads, the circular touch sensor is less expensive than traditional 12-pad to 16-pad circular sensors. BRIEF DESCRIPTION OF THE CONTENTS [0010] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. [0011] FIG. 1 illustrates a conventional linear touch sensor with straight edges between adjacent sensor pads. [0012] FIG. 2 illustrates a conventional linear touch sensor with jagged edges between adjacent sensor pads. [0013] FIG. 3 illustrates a conventional circular touch sensor with straight edges between adjacent sensor pads. [0014] FIG. 4 illustrates a conventional circular touch sensor with jagged edges between adjacent sensor pads. [0015] FIG. 5 illustrates a portable entertainment device that implements a circular touch sensor. [0016] FIG. 6 illustrates the circular touch sensor implemented in a system architecture, which may be implemented, for example, in the portable entertainment device of FIG. 5. The circular touch sensor has three sensor pads arranged according to a first implementation. [0017] FIG. 7 illustrates the circular touch sensor of FIG. 6 as it would appear if uncoiled and stretched out linearly. [0018] FIG. 8 illustrates a circular touch sensor in which the pad arrangement shown in FIG. 7 is replicated multiple times. [0019] FIG. 9 illustrates a circular touch sensor having three sensor pads arranged according to a second implementation. [0020] FIG. 10 illustrates the circular touch sensor of FIG. 9 as it would appear if uncoiled and stretched out linearly. Continue reading about Circular touch sensor... Full patent description for Circular touch sensor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Circular touch sensor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Circular touch sensor or other areas of interest. ### Previous Patent Application: Keyboard to be inside page of notebook Next Patent Application: Digital notepad with changeable writing style Industry Class: Computer graphics processing, operator interface processing, and selective visual display systems ### FreshPatents.com Support Thank you for viewing the Circular touch sensor patent info. 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