Method of reading coded data from a print medium before printing

1 . A method of using a mobile device to read coded data from a print medium configured to be printed on by the mobile device in a print direction, the mobile device including a printer, a sensor and processing means, the print medium comprising a laminar substrate defining first and second opposite faces, the first face bearing coded data, the method comprising the steps of:

using the sensor to sense at least some of the coded data from the print medium;

using the processing means to decode the coded data; and

printing onto the print medium only after the coded data has been decoded.

2 . A method according to claim 1 , wherein the coded data is indicative of a plurality of locations associated with the print medium, the decoding step including determining at least one of the locations.

3 . A method according to claim 2 , wherein the decoding step includes determining a position of the print medium relative to the sensor at the time the coded data was sensed, based at least partly on the determined location.

4 . A method according to claim 2 , wherein the coded data takes the form of a two-dimensional array of data, the sensor being configured to capture an image of a subset of the coded data, the subset of the coded data being sufficient to enable the location to be determined.

5 . A method according to claim 4 , the processing means being configured to determine a position of the print medium relative to the sensor at the time the coded data was sensed, based at least partly on the determined location and a position of the captured coded data in a capture field of the sensor.

6 . A method according to claim 5 , the mobile device further including a light emitting device, the method including the step of using the light emitting device to illuminate the print medium while the sensor senses the coded data.

7 . A method according to claim 1 , including the steps, performed during printing onto the print medium, of:

using the sensor to determine a clock signal; and

using the clock signal to synchronize the printing onto the print medium.

8 . A method according to claim 13 , wherein the step of using the sensor to sense the coded data includes capturing a first image of the coded data, and the step of generating the clock signal includes using the processor to perform the steps of;

determining a position of the print medium relative to the sensor at the time the coded data was sensed, based at least partly on the determined location;

using the sensor to capture subsequent images of the coded data as the printhead is being printed;

determining movement of the print medium during printing based on the subsequently captured images; and

deriving the clock signal based on the movement.

9 . A method according to claim 8 , wherein determining the movement during printing includes using the processing means to perform the steps of:

decoding the coded data captured in at least some of the subsequently captured images;

determining a position of the print medium relative to the sensor at the time each of the images was captured; and

determining the movement of the print medium based on the positions determined over time.

10 . A method according to claim 8 , wherein determining the movement during printing includes the step of performing pattern recognition on at least some of the coded data in at least some of the captured images to determine movement of the print medium relative to initial position.

11 . A method according to claim 1 , further including the step of determining movement of the print medium relative to sensor, based on the coded data sensed by the sensor.

12 . A method according to claim 11 , wherein determining the movement includes capturing a plurality of images of the coded data as the print medium moves past the sensor, and determining the movement based on the plurality of images.

13 . A method according to claim 12 , wherein determining the movement includes the steps of:

using the processing means to decode the coded data captured in at least some of the plurality of captured images;

determining a position of the print medium relative to the sensor at the time each of the images was captured; and

determining the movement of the print medium based on the positions determined over time.

14 . A method according to claim 12 , wherein determining the movement includes the step of performing pattern recognition to determine movement of the print medium relative to at least one absolute position of the print medium.

15 . A method according to claim 14 , including the step of obtaining the absolute position by using the processing means to decode the coded data in at least one of the captured images and obtaining the at least one absolute position from the decoded data.

16 . A method according to claim 15 , the mobile device further including a light emitting device, the method including the step of using the light emitting device to illuminate the print medium while the sensor senses the coded data.

17 . A method according to claim 12 , further including the steps of generating a clock signal based on the movement, and using the clock signal to synchronize the printing onto the print medium.

18 . A method according to claim 1 , wherein the medium includes at least one orientation indicator indicative of an orientation of the print medium, the method comprising determining the orientation from the orientation indicator before commencing printing.

19 . A method according to claim 18 , wherein the at least one orientation indicator is disposed at or adjacent an edge of the print medium.

20 . A method according to claim 19 , the print medium having a leading edge and a trailing edge defined relative to intended feed direction of the print medium through a media feed path, at least one of the at least one orientation indicators being disposed on or in the print medium at or adjacent the leading edge.