Method, system, and computer program product for control of platen movement during a live scan

• US 7,162,060 B1
• Filed: 10/25/1999
• Issued: 01/09/2007
• Est. Priority Date: 08/09/1999
• Status: Expired due to Fees

• Current Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Original Assignee: Cross Match Technologies Incorporated (Assa Abloy AB)
• Inventors: Scott, Walter Guy, Carver, John F., Barton, Gary, Smith, Tillman
• Primary Examiner(s): Mancuso; Joseph
• Assistant Examiner(s): Le; Brian
• Application Number:
  US09/425,888
• Time in Patent Office: 2,633 Days
• Field of Search: 382/124, 382/126, 382/127, 382/313, 382/314, 382/315, 340/5.52, 340/5.53, 340/5.82, 340/5.83, 340/356, 358/496, 358/497, 358/486, 358/481, 358/474, 250/234, 128/774, 356/71
• US Class Current: 382/126
• CPC Class Codes: G06V 40/1335 Combining adjacent partial images (e.g. slices) to create a composite input or reference pattern; Tracking a sweeping finger movement
• CPC Class Codes: H04L 12/40117 Interconnection of audio or video/imaging devices home automation networks H04L12/2803; bitstream network arrangements specially adapted for distribution of digital video signals H04N7/24
• CPC Class Codes: H04L 12/40123 Interconnection of computers and peripherals printer information exchange with computer G06F3/1293

Abstract

A method, system, and computer program product is provided that controls platen movement during a live scan. The platen moves in response to finger movement. The present invention then applies a counter force that counters the platen movement. In one embodiment, the counter force has a magnitude which is a function of the speed of the platen movement. The platen can move in a lateral direction (right or left) in response to the finger. The direction in which the counter force is applied is a direction that counters the platen movement in a determined direction. In one example, the force is applied through a motor that drives the platen in a direction opposite the direction of movement caused by the finger or fingers during the live scan. In this way, the counter force which is applied helps prevent a user from moving a finger too rapidly during the live scan. As a result, a high-quality fingerprint image can be obtained with less training and experience in live scan fingerprinting. A user need not follow complicated live scan bars or other indications of a recommended speed or rate of platen movement.

Claims

1. A method for control of platen movement during a live scan, wherein the direction and speed of the movement is initiated in response to movement of a finger during the live scan, comprising the steps of:

(A) determining the speed of platen movement;

(B) determining the direction of platen movement;

(C) applying a variable voltage drive signal to a motor to generate a counter force when the determined speed of platen movement is above a minimum threshold value, the variable voltage drive signal having a voltage which is a function of the determined platen movement speed and a direction that counters the platen movement in the determined direction, and

(D) applying the counter fource through the motor to control the platen movement.

2. The method of claim 1, wherein the variable voltage drive signal has a magnitude which is an approximately linear function or a linear function of the determined platen movement speed.

3. The method of claim 1, wherein the variable voltage drive signal has a magnitude which is an approximately linear function or a linear function of the determined platen movement speed.

4. The method of claim 1, wherein the determined platen movement speed has a range in which a drive signal can be applied that is subdivided into n sub-divisions, where n is a whole number equal to or greater than 2, and the magnitude of drive signal, which can be applied to the motor in said applying step (C) is determined based on n respective linear functions, each of the n functions having a different slope such that the slopes of the n functions increase across the range of platen movement speed.

5. The method of claim 1, wherein the determined platen movement speed has a range in which a counter force can be applied that is subdivided into n sub-divisions, and the magnitude of drive signal which can be applied to the motor in said applying step (C) is determined based on first through fourth respective linear functions, each of the first through functions having a different slope such that the slope of the first through fourth functions increase across the range of platen movement speed at an approximately exponential function.

6. The method of claim 1, wherein said applying step (C) comprises generating a single supply drive signal having a voltage which is a function of a time interval count and a direction opposing the platen movement.

7. The method of claim 1, wherein said speed step (A) comprises reading a time interval count in response to receiving a position incremental signal.

8. The method of claim 7, wherein said applying step (C) comprises the steps of:

when the determined platen movement speed is in a first range, calculating a drive signal value equal to the difference between a maxium threshold and the read time interval count divided by 16 plus a mid-position bias offset;

when the determined platen movement speed is in a second range,

calculating a drie signal value equal to the difference between a maximum three and the read time interval count divided by 12 plus a mid-position bias offset;

when the determined platen movement speed is in a third range, calculating a drive signal value equal to the difference between maximum threshold and the read time inteval count divided by 10 plus a mid-position bias offset; and

when the determined platen movement speed is in a fourth range, calculating a drive signal value equal to the difference between a maximum threshold and the read time interval count divided by 8 plus a mid-position bias offset.

9. The method of claim 8, wherein said determining step (b) comprises reading a Boolean value set in response to a direction of platen movement along an axis perpendicular to the up-to-crease direction of a fingerprint.

10. The method of claim 1, wherein the speed of platen movement in a linear speed.

11. A system for control of platen movement during a live scan, wherein the direction and speed of the movment is initiated in response to movement of a finger during the live scan, comprising:

(A) means for determining the speeed of platen movement;

(B) means for determining the direction of platen movement;

(C) means for applying a variable voltage drive signal to a motor to generate a counter fource when the determined speed of platen movement is above the minimum theshold value, the variable voltage drive signal having a voltage which is a function of the detemined platen movement speed and a direction that counters the platen movement in the determined direction; and

(D) means for applying the counter force through the motor to control the platen movement.

12. The system of claim 11, wherein means for determining the speed of platen movement includes a means for determining the linear speed of platen movement.