Navigation and fingerprint sensor

• US 20050083310A1
• Filed: 10/20/2003
• Published: 04/21/2005
• Est. Priority Date: 10/20/2003
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Avago Technologies ECBU IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Safai, Max, Uebbing, John Julian
• Granted Patent: US 7,460,109 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/0338 Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing

Abstract

A pressure sensitive cursor control suitable for applications that include cellular phones and personal data assistants includes a pressure sensor array suitable to detect a human fingerprint. Cursor control is provided by subtle finger movement. Sequential images of the finger are captured and compared to determine planar movement or data entry. Performance may be improved by sampling zones within the captured image and comparing the zones with those in an earlier image. Performance could also be improved by subsampling the array. While the full resolution of the pressure-sensing array is needed to capture ones fingerprint and execute an authentication function only a subsampled image from the array is needed to derive meaningful navigation data. The pressure sensor array is designed on a glass substrate in order to drive down the unit cost. The silicon companion chip where the data is interpreted also drives the array and can therefore sub-sample the array when navigating and/or get a full resolution image when authenticating.

Claims

1. A device comprising:

a mobile embedded device having a cursor manipulator including,

the cursor manipulator including,

a sensing surface operative to sense contact by the human finger,

the contact corresponding to applied pressure,

a pressure sensor array disposed on the sensing surface, wherein a measurement of the plurality of pressure sensors corresponds to an image, and

an image detector, receiving images from the pressure sensor array, generating cursor manipulation corresponding to changes between the images.

2. The device, as defined in claim 1, wherein the cursor manipulation corresponds to planar directional movement.

3. The device, as defined in claim 1, wherein the cursor manipulation corresponds to data entry.

4. The device, as defined in claim 1, the image detector including:

a controller;

a multiplex driver, transceiving data from the controller;

an image array, receiving data from the multiplex driver;

sense amplifiers, connected to the image array, transceiving data from the controller;

a port transceiving data with the controller;

current read access memory (RAM) connected to the sense amplifiers;

reference RAM, connected to the current RAM;

a predictor;

a cross-correlator receiving data from the current RAM, reference RAM, and the predictor; and

an interpolator, receiving data from the cross-correlator, transmitting data to the predictor and the controller.

5. The device, as defined in claim 1, wherein the mobile embedded device is selected from a group comprising personal data assistants and cellular phones.

6. A system for providing cursor manipulation when using a human finger comprising:

sensing surface operative to sense contact by the human finger, the contact corresponding to applied pressure;

a pressure sensor array disposed on the sensing surface, wherein a measurement of the plurality of pressure sensors corresponds to an image; and

an image detector, receiving images from the pressure sensor array, generating cursor manipulation corresponding to changes between the images.

7. The system, as defined in claim 6, wherein the cursor manipulation corresponds to planar directional movement.

8. The system, as defined in claim 6, wherein the cursor manipulation corresponds to data input.

9. The system, as defined in claim 6, the image detector including:

a controller;

a multiplex driver, transceiving data from the controller;

an image array, receiving data from the multiplex driver;

sense amplifiers, connected to the image array, transceiving data from the controller;

a serial port transceiving data with the controller;

current read access memory (RAM) connected to the sense amplifiers;

reference RAM, connected to the current RAM;

a predictor;

a cross-correlator receiving data from the current RAM, reference RAM, and the predictor; and

an interpolator, receiving data from the cross-correlator, transmitting data to the predictor and the controller.

10. A method for finger navigation comprising:

sampling a portion of an array of pressure sensors to generate a first sample;

re-sampling the portion of the array to generate a second sample; and

comparing the first and second samples to determine navigational movement.

11. A method, as defined in claim 10, wherein the portion is a subset of the array.

12. A method, as defined in claim 11, wherein the subset is a periodic selection of pressure sensors.

13. A method, as defined in claim 11, wherein the subset is a region of pressure sensors.

14. A method, as defined in claim 13, wherein the region has an area comparable to a fingerprint.

15. A method, as defined in claim 13, wherein the subset further comprises a second region of pressure sensors.