Static charge dissipation for an active circuit surface

#The present invention relates in general to the field of static discharge dissipation, and more particularly, to a structure and method for protecting active circuits on sensor surfaces from the environment of intended use.

#Without limiting the scope of the invention, its background is described in connection with the protection of integrated circuit fingerprint sensors from the environment during regular use, as an example.

#Heretofore, in this field, the detection of fingerprint patterns, composed of lines or ridges and valleys, has been useful for the identification of specific individuals based on the observation that each individual person has a unique fingerprint. Fingerprints, therefore, can be used not only to positively identify individuals, but to exclude individuals whose fingerprint profile does not match a pre-existing set of patterns.

#For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:

#FIG. 1 is a block diagram of a sensor array according to the present invention;

#FIG. 2 illustrates the physical structure of the individual sensor cells and their electrical operation according to the present invention;

#While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of ways to make and use the invention and do not delimit the scope of the invention.

#By way of background, referring now to FIG. 1, there is shown a block diagram of a user input device 1. User input device 1 is preferably integrated into a single chip, and it includes an array 2 of sensors or pixel cells 3. For purposes of illustration, array 2 is shown comprising nine cells 3. In an actual device, more than nine cells would more likely be included. Each individual sensing cell 3 represents one pixel of the array 2 and is generally smaller than the width of a fingerprint ridge. Enough cells 3 are included in array 2 so that several ridges and valleys of a fingerprint may be detected. In a preferred embodiment, pixel cells 3 are on a pitch of approximately 50 μm, which corresponds to a resolution of approximately 508 dots per inch (dpi) for a fingerprint image.

#Device 1 includes a horizontal scanning stage 4 and a vertical scanning stage 5. Scanning stages 4 and 5 enable detection from one cell in array 2 at a time according to a predetermined scanning pattern.