Digital printing system

1. A digital printing system, comprising:

an intermediate transfer member (ITM), which is configured to receive a printing fluid so as to form an image;

a continuous target substrate, which is configured to engage with the ITM at an engagement point for receiving the image from the ITM, wherein, at the engagement point, the ITM is configured to move at a first velocity and the continuous target substrate is configured to move at a second velocity;

an electrical motor configured to move one or both of the ITM and the target substrate; and

a processor, which is configured to: (i) receive one or more measurements of an electrical current flowing through the electrical motor, (ii) evaluate a trend in the measured electrical current, and (iii) match the first velocity and the second velocity at the engagement point, based on the evaluated trend.

2. The system according to claim 1 , and comprising first and second drums, wherein the first drum is configured to rotate at a first direction and first rotational velocity so as to move the ITM at the first velocity, and wherein the second drum is configured to rotate at a second direction and at a second rotational velocity so as to move the continuous target substrate at the second velocity, and wherein the processor is configured to engage and disengage between the ITM and the continuous target substrate at the engagement point by displacing one or both of the first drum and the second drum.

3. The system according to claim 2 , wherein the processor is configured to receive an electrical signal indicative of a difference between the first and second velocities, and, based on the electrical signal, to match the first and second velocities.

4. The system according to claim 2 , wherein the processor is configured to set at least one operation selected from a list consisting of (a) timing of engagement and disengagement between the first and second drums, (b) a motion profile of at least one of the first and second drums, and (c) a size of a gap between the disengaged first and second drums.

5. The system according to claim 1 , wherein the processor is configured to match the first velocity and the second velocity by reducing the evaluated trend of the measured electrical current.

6. The system according to claim 5 , wherein the evaluated trend comprises a slope of the electrical current as a function of time, across a predefined time interval.

7. The system according to claim 5 , wherein the processor is configured to compensate for a thermal expansion of at least one of the first and second drums by reducing the evaluated trend in of the measured electrical current.

8. The system according to claim 5 , wherein the continuous target substrate comprises a first substrate having a first thickness, or a second substrate having a second thickness, different from the first thickness, and wherein the processor is configured to compensate for the difference between the first thickness and the second thickness by reducing the evaluated trend of the measured electrical current.

9. The system according to claim 1 , wherein the ITM is formed of a loop that is closed by a seam section, and wherein the processor is configured to prevent physical contact between the seam section and the continuous target substrate, by:

causing temporary disengagement between the ITM and the continuous target substrate during time intervals in which the seam section traverses the engagement point; and

backtracking the continuous target substrate during the time intervals, so as to compensate for the temporary disengagement.

10. The system according to claim 9 , and comprising a backtracking mechanism, which is configured to backtrack the continuous target substrate, and which comprises at least first and second displaceable rollers having a physical contact with the continuous target substrate and configured to backtrack the continuous target substrate by moving the rollers relative to one another.

11. A method for matching velocities between substrates in digital printing, the method comprising:

receiving a printing fluid on an intermediate transfer member (ITM), so as to form an image;

engaging a continuous target substrate with the ITM at an engagement point for receiving the image from the ITM, and, at the engagement point, using an electrical motor for moving the ITM at a first velocity and moving the continuous target substrate at a second velocity, and receiving one or more measurements of an electrical current flowing through the electrical motor;

evaluating a trend in the measured electrical current; and

matching the first velocity and the second velocity at the engagement point, based on the evaluated trend.

12. The method according to claim 11 , and comprising rotating a first drum at a first direction and first rotational velocity so as to move the ITM at the first velocity, and rotating a second drum at a second direction and second rotational velocity so as to move the continuous target substrate at the second velocity, and engaging and disengaging between the ITM and the continuous target substrate at the engagement point by displacing one or both of the first drum and the second drum.

13. The method according to claim 12 , wherein matching the first velocity and the second velocity comprises receiving an electrical signal indicative of a difference between the first and second velocities, and, based on the electrical signal, matching the first and second velocities.

14. The method according to claim 12 , wherein matching the first and second velocities comprises setting at least one operation selected from a list consisting of (a) timing of engagement and disengagement between the first and second drums, (b) a motion profile of at least one of the first and second drums, and (c) a size of a gap between the disengaged first and second drums.

15. The method according to claim 11 , wherein matching the first velocity and the second velocity comprises reducing the evaluated trend of the measured electrical current.

16. The method according to claim 15 , wherein the evaluated trend comprises a slope of the electrical current as a function of time, across a predefined time interval.

17. The method according to claim 15 , wherein matching the first velocity and the second velocity comprises compensating for a thermal expansion of at least one of the first and second drums by reducing the evaluated trend of the measured electrical current.

18. The method according to claim 15 , wherein the continuous target substrate comprises a first substrate having a first thickness, or a second substrate having a second thickness, different from the first thickness, and wherein matching the first velocity and the second velocity comprises compensating for the difference between the first thickness and the second thickness by reducing the evaluated trend of the measured electrical current.

19. The method according to claim 11 , wherein the ITM is formed of a loop that is closed by a seam section, and comprising preventing physical contact between the seam seam section and the continuous target substrate, by:

causing temporary disengagement between the ITM and the continuous target substrate during time intervals in which the seam section traverses the engagement point; and

backtracking the continuous target substrate during the time intervals, so as to compensate for the temporary disengagement.

20. The method according to claim 19 , and comprising a backtracking mechanism that comprises at least first and second displaceable rollers having a physical contact with the continuous target substrate, wherein backtracking the continuous target substrate comprises moving the rollers relative to one another.