Motion induced blur minimization in a portable image reader
The invention describes a method and apparatus for reducing motion-induced blur inherent in portable image readers. The method consists of adding a time delay to the operation of the reader after the trigger has been activated, in order to delay the start of the acquisition cycle. When the trigger or button on a portable imaging reader is pulled or pressed, the motion imparted on the reader can be excessive. Images acquired during this time generally suffer from excessive blurring. Incorporating a short delay between trigger and acquisition, allows the image acquisition to occur at an optimal time when the reader motion is at a minimum. The time delay may be of a fixed duration in the range of 50 ms to 250 ms. In another arrangement, the time delay may determined by the time it takes for the reader motion to decelerate below a predetermined threshold.
1 . A portable image reader comprising;
a trigger for providing an activation signal to initiate an image acquisition sequence;
a delay device coupled to said trigger for delaying said activation signal for a predetermined delay time to reduce the effect of image blur on image acquisition by the image reader; and
acquisition circuitry coupled to said delay device for receiving said delayed activation signal for initiating said image acquisition sequence.
2 . A portable image reader as claimed in claim 1 wherein the delay device comprises a monostable multivibrator.
3 . A portable image reader as claimed in claim 1 wherein the delay device comprises a central processing unit (CPU).
4 . A portable image reader as claimed in claim 1 wherein the delay device provides a delay in the order of 50 ms to 250 ms.
5 . A portable image reader as claimed in claim 1 wherein the delay device provides a delay between 100 ms and 150 ms.
6 . A portable image reader as claimed in claim 1 wherein the delay device comprises an accelerometer for measuring velocity of the image reader and a comparator for determining when the reader has decelerated below a predetermined threshold.
7 . A portable image reader comprising:
a trigger for providing an activation signal to initiate an image acquisition sequence;
a delay device coupled to said trigger for delaying said activation signal until motion imparted on said portable image reader has substantially decelerated to reduce the effect of image blur on image acquisition by the image reader; and
acquisition circuitry coupled to said delay device for receiving said delayed activation signal for initiating said image acquisition sequence.
8 . A portable image reader as claimed in claim 7 wherein the delay device comprises an accelerometer for measuring velocity of the image reader and a comparator for determining when the reader has decelerated below a predetermined threshold.
9 . A method of reducing the blurring effects of motion in a portable image reader comprising the steps of:
a) triggering an activation signal for the image reader;
b) delaying the activation signal for a predetermined period of time; and
c) applying the delayed activation signal to the portable imager reader for initiating an image acquisition sequence.
10 . A method of reducing the blurring effects of motion in a portable image reader wherein the predetermined delay time is in the order of 50 ms to 250 ms.
11 . A method of reducing the blurring effects of motion in a portable image reader wherein the predetermined delay time is between 100 ms and 150 ms.
12 . A method of reducing the blurring effects of motion in a portable image reader comprising the steps of.
a) triggering an activation signal for the image reader;
b) delaying the activation signal for the image reader until motion imparted to the portable image reader has substantially decelerated below a predetermined threshold; and
c) applying the delayed activation signal to the portable imager reader for initiating an image acquisition sequence.