CONTROLLING A PRINTING PROCESS
A printing system ( 10, 11 ) includes (i) an intermediate transfer member (ITM) ( 44 ), which is configured to receive ink droplets from an ink supply subsystem to form an ink image thereon, and to absorb at least part of an optical radiation ( 81 ) directed to the ITM ( 44 ) for heating the ITM ( 44 ), and (ii) an optical assembly ( 33 ) having one or more sensors ( 25 ), which are facing the ITM ( 44 ), and in response to sensing an optical signal emitted from at least one of the ITM ( 44 ) and a substance being carried by the ITM ( 44 ), the optical assembly ( 33 ) is configured to produce a signal indicative of the substance.
1 . A printing system, comprising:
an intermediate transfer member (ITM), which is configured to receive ink droplets from an ink supply subsystem to form an ink image thereon, and to absorb at least part of an optical radiation directed to the ITM for heating the ITM; and
an optical assembly having one or more sensors, which are facing the ITM, wherein, in response to sensing an optical signal emitted from at least one of the ITM and a substance being carried by the ITM, the optical assembly is configured to produce a signal indicative of the substance.
2 . The printing system according to claim 1 , and comprising a processor, which is configured to control an operation of the printing system responsively receiving the signal.
3 . The printing system according to claim 1 , wherein the ITM is configured to transfer the ink image to a target substrate, wherein the substance comprises at least a portion of the target substrate that remains on the ITM after the image has been transferred to the target substrate, and wherein the signal is indicative of the at least portion of the target substrate that remains on the ITM.
4 . The printing system according to claim 1 , wherein the optical assembly comprises one or more light sources, which are facing the ITM and are configured to direct the optical radiation to a surface of the ITM.
5 . The printing system according to claim 4 , wherein at least one of the light sources comprises an infrared (IR) light source, the optical radiation comprises one or more IR beams, and the optical signal comprises an IR radiation, and wherein at least one of the sensors is configured to sense the IR radiation emitted from at least one of the ITM and the substance responsively to directing the one or more IR beams.
6 . (canceled)
7 . The printing system according to claim 5 , wherein in response to directing the one or more IR beams: (i) when facing the substance being carried by the ITM, at least a sensor among the sensors is configured to produce a first signal indicative of a first portion of the sensed IR radiation, and (ii) when facing the ITM, the sensor is configured to produce a second signal indicative of a second portion of the sensed IR radiation.
8 . The printing system according to claim 7 , wherein the optical assembly comprise at least first and second sensing assemblies, which: (i) are mounted on the printing system at first and second locations, respectively, along an axis of the ITM, and (ii) are configured to direct first and second IR beams to first and second positions, respectively, on the surface of the ITM.
9 . The printing system according to claim 8 , wherein at least part of the first and second IR beams overlap one another.
10 . The printing system according to claim 8 , wherein at least one of the first and second sensing assemblies comprises the IR light source and the sensor integrated together.
11 . The printing system according to claim 7 , wherein the ITM is configured to absorb the IR beams, and wherein the second signal is indicative of zero IR radiation emitted from the ITM.
12 . (canceled)
13 . The printing system according to claim 1 , wherein the ITM is moved along a first axis, and the one or more sensors of the optical assembly are arranged along a second axis, different from the first axis.
14 . (canceled)
15 . The printing system according to claim 13 , and comprising at least an impression station, which is configured to transfer the image from the ITM to the target substrate, and wherein the optical assembly is positioned, along the first axis, subsequent to the impression station.
16 . (canceled)
17 . The printing system according to claim 1 , and comprising one or more magnetic sensors, which are facing the ITM and are configured to produce an additional signal in response to sensing an altered magnetism from the ITM.
18 . (canceled)
19 . The printing system according to claim 1 , wherein the substance comprises at least a portion of a first target substrate configured to receive the ink image from the ITM, and comprising a processor, which is configured to receive an additional signal indicative of a second target substrate being introduced into the printing system, and wherein the processor is configured to stop the operation of the printing system when: (i) the signal is indicative of the substance being carried by the ITM, and (ii) the additional signal is indicative of the second target substrate being introduced into the printing system.
20 . The printing system according to claim 19 , wherein the processor is configured to present an alert when: (i) the signal is indicative of the substance being carried by the ITM, and (ii) no additional target substrate being introduced into the printing system.
21 . A method for detecting a substance in a printing system, the method comprising:
positioning an optical assembly having one or more sensors, to face an intermediate transfer member (ITM), which is adapted to be moved and receive ink droplets from an ink supply subsystem to form an ink image thereon, and to absorb at least part of an optical radiation directed to the ITM for heating the ITM; and
sensing an optical signal emitted from at least one of the ITM and the substance being carried by the ITM, and producing a signal indicative of the substance.
22 . (canceled)
23 . The method according to claim 21 , wherein the ITM is configured to transfer the ink image to a target substrate, and wherein the substance comprises at least a portion of the target substrate that remains on the ITM after the image has been transferred to the target substrate, and wherein the signal is indicative of the at least portion of the target substrate that remains on the ITM.
24 . The method according to claim 21 , and comprising positioning one or more light sources to face the ITM, and directing the optical radiation to a surface of the ITM.
25 . The method according to claim 24 , wherein at least one of the light sources comprises an infrared (IR) light source, the optical radiation comprises one or more IR beams, and the optical signal comprises an IR radiation, and wherein sensing the optical signal comprises sensing the IR radiation emitted from at least one of the ITM and the substance responsively to directing the one or more IR beams.
26 . (canceled)
27 . The method according to claim 25 , wherein in response to directing the one or more IR beams: (i) when facing the substance being carried by the ITM, producing a first signal indicative of a first portion of the sensed IR radiation, and (ii) when facing the ITM, producing a second signal indicative of a second portion of the sensed IR radiation.
28 - 39 . (canceled)