212 is positioned within the container 108 such that excess polymeric material within the container 108 can migrate downward from upper portions of the container 108, e.g., portions adjacent to the opening 310, into the collection element 212. In examples, one or more of the containment walls 352a-352d may be movable such that the removable collection element 212 can be accessible to a user for emptying. In other examples, one or more of the containment walls 352a-352d may include a door to provide a user with access to the removable collection element 212.

FIG. 4 is a simple schematic diagram that illustrates another example of a system to service a print blanket. The example of a print blanket service system 100 illustrated at FIG. 4 is substantially similar to the system as described with respect to FIG. 3, except that in the example of FIG. 4 the system includes a flexible containment blade 210. As with the example of FIG. 3, the container 108 of FIG. 4 is positioned to collect a portion of polymeric material that is scraped from the layer 304 of residue polymeric material on the ECS 102 by the doctor blade 104. The containment blade 210 is to hold within the container 108 the scraped portion of polymeric material, and to hold liquified polymeric material. In examples, the liquified polymeric material is a product of the heating element 106 having caused heating of the container and the solid or semi-solid polymeric material previously scraped from the ECS 102 that is situated within the container. As with the example of FIG. 3, the container 108 of FIG. 4 is positioned to make heated polymeric material in a liquid state available to be picked up by the ECS 102 as the ECS 102 is rotated adjacent to the container 108. In examples wherein the polymeric material is a high viscosity polymeric material (e.g., a thermoplastic print agent), the containment blade 210 is to guide the scraped polymeric material away from the ECS 102, and to prevent cold and solid material from being pulled back to the ECS 102.

In this example, the containment blade 210 is attached to containment wall 352a of the container 108, and a first surface 210a of the containment blade 210 is positioned to hold scraped and liquid polymeric material within the container 108. In examples, the doctor blade 104 may be attached to a doctor blade holder element that is a component of the containment wall 360. In examples, the containment blade 210 may be attached to the containment wall 352a via one or more of a clamp, bolt, screw, welding, or glue.

Continuing with the example of FIG. 4, a gap 402 exists between the containment blade 210 leading edge 210b and the ECS 102. The gap 402 is of a width that is close enough such that the containment blade will be effective in containing the scraped and liquified polymeric material, and yet wide enough to avoid the leading edge 210b colliding with and/or displacing polymeric material deposited on the ECS 102, or the ECS itself. In examples the gap may be between 0.25 mm and 2.00 mm. The gap 402, in combination with a flexible containment blade 210, is advantageous to avoid damage to the ECS 102 and to the cleaning system 100 that might otherwise by caused by the containment blade 210 leading edge 210b colliding with the polymeric material deposited on the ECS 102 to cause scattering of polymeric material outside the container 108, or by contact with the ECS 102.

FIG. 5 is a simple schematic diagram that illustrates another example of a system to service a print blanket. The example of a print blanket service system 100 illustrated at FIG. 5 is substantially similar to the system as described with respect to FIG. 3, with exceptions noted in this paragraph. In the example of FIG. 5 the container 108 has containment walls 552a-552d. Returning to FIG. 3, in that example a floor structure 506 of the container is situated substantially horizontally beneath the ECS 102 such that scraped polymeric material can fall directly onto the floor structure 506. In the present example of FIG. 5, however, the floor structure 506 of the container 108 is situated at approximately a forty-five-degree angle and a similar height and alongside the ECS 102. In the example of FIG. 5, notwithstanding that the floor structure 506 is not beneath the ECS 102, the container 108 is positioned to receive polymeric material scraped from the ECS 102 by the doctor blade 104. Further, in the example of FIG. 5 notwithstanding that the floor structure 506 is not beneath the ECS 102, the container 108 is positioned to make heated polymeric material, in a liquified form, accessible to be picked up by the ECS 102 as the ECS 102 is rotated adjacent to an opening 310 of the container 108.

FIG. 6 is a simple schematic diagram that illustrates another example of a system to service a print blanket. The example of a print blanket service system 100 illustrated at FIG. 6 is substantially similar to the system as described with respect to FIG. 5, except that in the example of FIG. 6 the system includes a flexible containment blade 210. As with the example of FIG. 5, the floor structure 506 of the container 108 is situated at approximately a forty-five-degree angle and a similar height and alongside the ECS 102. The container 108 is positioned to collect a portion of polymeric material that is scraped from scraped from the layer 304 of residue polymeric material on the ECS 102 by the doctor blade 104.

In this example, the containment blade 210 is attached to a containment wall 552e of the container 108, and a first surface 210a of the containment blade 210 is positioned to hold within the container 108 solid or semi-solid polymeric material recently scaped by the doctor blade 104 into the container 108. The first surface 210a of the containment blade 210 is likewise positioned to hold within the container 108 polymeric material that was previously scraped from the ECS 102 by the doctor blade 104, and that was subsequently liquified as a result of heat applied to the floor portion 506 by the heating element 106. As with the example of FIG. 5, the container 108 of FIG. 6 is positioned to make heated polymeric material in a liquid state available to be picked up by the ECS 102 as the ECS 102 is rotated adjacent to the container 108.

A gap 402 exists between the containment blade 210 leading edge 210b and the ECS 102. The gap 402 is advantageous to avoid damage to the ECS 102 and to the cleaning system 100 that could occur if the containment blade 210 leading edge 210b were to contact the polymeric material deposited on the ECS 102. Such contact could cause a messy dispersion of polymeric material outside the container 108. Such contact, with sufficient force, could likewise cause damage to the ECS 102. As discussed with respect to FIG. 4, the risk of damaging the ECS 102 can be mitigated somewhat by utilizing a containment blade 210 that is capable of flexing or bending should there be an unintended contact between the containment blade 210 and the ECS 102.

FIG. 7A is a simple schematic diagram and FIG. 7B is a perspective view diagram that illustrate another example of a system to service a print blanket. The print blanket servicing system 100 includes an ECS 102, a doctor blade 104, a heating element 106, and a container 108. The print blanket 302 is situated to be rotatable, e.g., is situated upon a drum or belt (not depicted in FIGS. 7A and 7B. The print blanket 302 is in a position to receive from a photoconductive surface, during contact as the print blanket 302 and the photoconductive surface are rotated in opposition to one another, a layer of polymeric material, e.g., a thermoplastic print agent. In examples the layer of polymeric material received at the print blanket 302 is a one separation of multiple separations in a printing process that are to be successively applied by the print blanket to a substrate to form a printed image.

In this example the ECS 102 is wrapped around a drum 702. The drum 702 is to revolve and cause the ECS 102 to engage the revolving print blanket 302. As a result of this engagement, the ECS 102 is to receive a layer 304 of residue polymeric material from the print blanket 302. In an example the polymeric material on the blanket 302 is residue that remains after the print blanket 302 had deposited print agent upon a substrate to form an image separation on the substrate. The ECS 102 is to remove excess residue from print blanket 302 via a rotating contact with the print blanket 302.

A doctor blade 104 is situated at a position wherein the doctor blade can scrape a portion of polymeric material from the ECS 102 into the container 108. In this example the heating element 106 is a convection heater situated adjacent to a floor structure 306 of the container 108 to heat the container and thereby heat the polymeric material held in the container 108.

Continuing at FIGS. 7A and 7B, the system 100 includes a biasing device 718. The biasing device 718 is to bias the doctor blade 104 towards the ECS 102 to cause the doctor blade 104 to scrape the ECS with a pressure that is to remove of a portion of the polymeric material while leaving an operative layer of polymeric material on the ECS. As used herein an “operative layer” of polymeric material upon an ECS refers generally to a layer of polymeric material that has a predetermined thickness and that is to be utilized by an ECS to remove residue from a print blanket as the ECS and the print blanket are rotated in contact with one another. In examples, the biasing device 718 may be, or may include, a spring, such that doctor blade 104 is spring-loaded to bias towards ECS 102 and thereby cause the doctor blade 104 to scrape the ECS 102. In examples, the biasing device 718 may be a compression spring. In other examples, the biasing device may be a tension spring any other type of spring or any other device that causes the doctor blade 104 to bias towards the ECS 102.

In examples, the amount of polymeric material to be scraped from the ECS 102 by the doctor blade 104 is a function of the attack angle and the applied force of the doctor blade relative to the ECS. In a particular example the doctor blade scraping is achieved by having a doctor blade 104 with an attack angle of between 15 and 45 degrees, a length of approximately 2 mm, a blade thickness of 0.2 mm, and a biased deflection of 3±1 mm. In this example the force applied by the biased doctor blade to the ECS 102 is between 6 Nmm and 2 Nmm. In this example, the operative layer of polymeric material to remain on the ECS after scraping by the doctor blade 104 is between 10 microns and 50 microns. In yet another example, the doctor blade may have a length of between 9 mm and 15 mm, with an attack angle between 15 and 45 degrees, and an applied force between 4 Nmm and 17 Nmm. In this example, the operative layer of polymeric material to remain on the ECS after scraping by the doctor blade 104 is between 10 microns and 50 microns.

The container 108 is positioned to collect the portions of polymeric material print agent scraped by the doctor blade 104 from the layer 304 of residue polymeric material on the ECS 102. The container 108 is positioned to make a liquified portion of the polymeric material 308 in the container 108 accessible to be picked up by the ECS 102 as the ECS 102 is rotated adjacent to an opening 310 of the container 108.

Continuing at FIGS. 7A and 7B, the system 100 includes a removable collection element 212. In this example, the collection element 212 is positioned within the container 108 such that excess polymeric material within the container 108 can migrate into the collection element 212. In examples, one or more of the containment walls 352a-352d may be movable, or include a door, such that the removable collection element 212 can be accessible to a user for emptying.

In the example of FIGS. 7A and 7b, the system 100 includes a sensor 720 to measure a level or amount of polymeric material held within the removable collection element 212. Based upon the measurement of the level or amount of polymeric material at the collection element 212, the system 100 may determine a “full” condition. Upon determination of the full condition, system 100 may send an instruction to cause emptying of the collection element 212. In examples the instruction may be an instruction for display to a user. In other examples, the instruction may be an instruction sent to a component of system 100, or another system, to cause automatic emptying of collection element 212.

FIG. 8 is a simple schematic diagram illustrating an LEP printer implementing a system to service a print blanket, according to another example of the principles described herein. In this example, a LEP printer 800 includes a photoconductive surface 802, a charging element 804, an imaging assembly 806, a print blanket 302, an impression cylinder 808, a set of five developer assemblies 810, and a system 100 to service the print blanket.

According to the example of FIG. 8, a pattern of electrostatic charge is formed on the photoconductive surface 802 by rotating a clean, bare segment of the photoconductive surface 802 under a charging element 804. The photoconductive surface 802 in this example is cylindrical in shape, e.g., is attached to a first cylindrical drum 812, and rotates in a direction of arrow 814. In other examples, a photoconductive surface may planar or part of a belt-driven system.

The charging element 804 may include a charging device, such as a charge roller, corona wire, scorotron, or any other charging device. A uniform static charge is deposited on the photoconductive surface 802 by the charging element 804. As the photoconductive surface 802 continues to rotate, it passes an imaging assembly 806 where one or more laser beams dissipate localized charge in selected portions of the photoconductive surface 802 to leave an invisible electrostatic charge pattern (“latent image”) that corresponds to the image to be printed. In some examples, the charging element 804 applies a negative charge to the surface of the photoconductive surface 802. In other implementations, the charge is a positive charge. The imaging assembly 806 then selectively discharges portions of the photoconductive surface 802, resulting in local neutralized regions on the photoconductive surface 802.

Continuing with the example of FIG. 8, a set of five developer assemblies 810 is disposed adjacent to the photoconductive surface 802 and may correspond to various print fluid colors such as cyan, magenta, yellow, black, a custom spot color, and the like. There may be one developer assembly 810 for each print fluid color. In other examples, e.g., black and white printing, a single developer assembly 810 may be included in LEP printer 800. During printing, the appropriate developer assembly 810 is engaged with the photoconductive surface 802. The engaged developer assembly 810 presents a uniform film of print fluid to the photoconductive surface 802. The print fluid contains electrically charged pigment particles which are attracted to the opposing charges on the image areas of the photoconductive surface 802. As a result, the photoconductive surface 802 has a developed image on its surface, i.e., a pattern of print fluid corresponding with the electrostatic charge pattern (also sometimes referred to as a “separation”).

The print fluid is transferred from the photoconductive surface 802 to print blanket 302. The print blanket 302 may be in the form of a print blanket attached to a rotatable second cylindrical drum 816. In other examples, the print blanket may be in the form of a belt or other transfer system. In this particular example, the photoconductive surface 802 and print blanket 302 are on drums 812 and 816, respectively, that rotate relative to one another, such that the color separations are transferred during the relative rotation. In the example of FIG. 8, the print blanket 302 rotates in the direction of arrow 818. The transfer of a developed image from the photoconductive surface 802 to the print blanket 302 may be known as the “first transfer”, which takes place at a point of engagement between the photoconductive surface 802 and the print blanket 302.

Once the layer of print fluid has been transferred to the print blanket 302, it is next transferred to a print substrate 820. In this example, print substrate 820 is a web substrate moving along a substrate path in a substrate path direction 822. In other examples, the print substrate may a sheet substrate that travels along a substrate path. This transfer from the print blanket 302 to the print substrate 820 may be deemed the “second transfer”, which takes place at a point of engagement between the print blanket 302 and the print substrate 820. The impression cylinder 808 can both mechanically compress the print substrate 820 into contact with the print blanket 302 and also help feed the print substrate 820. In examples, the print substrate 820 may be a conductive or a non-conductive print substrate, including, but not limited to, paper, cardboard, sheets of metal, metal-coated paper, or metal-coated cardboard. In examples, the print substrate 820 with a printed image may be moved to a position to be scanned by an inline color measurement device 824, such as a spectrometer or densitometer, to generate optical density and/or background level data.

Continuing with the example of FIG. 8, the LEP printer includes a system 100 for servicing print blankets utilizing thermoplastic print agent that is similar to the example system 100 of FIG. 3 in that it includes the rotatably mounted ECS 102, a doctor blade 104, a heating element 106, and a container 108. In other examples the system 100 may include a containment blade (e.g., a containment blade such as containment blade 210 FIGS. 2, 4, 6), and/or a liquid level sensor (e.g., a liquid level sensor such as sensor 720 of FIGS. 7A and 7B).

In this example the LEP printer 800 includes a controller 830 operatively connected to components of the LEP printer, including system 100. Controller 830 represents the processing and memory resources and the programming, electronic circuitry and components needed to control the operative elements of LEP printer 800. Controller 830 may include distinct control elements for individual printer components. In the example shown in FIG. 8, controller 830 includes a processing resource 840 and a computer readable medium 850 with control instructions 860 that represent programming to control the voltage level applied by a voltage source, e.g., a power supply, to the imaging assembly 806, the charging element 804, one or more of the developer assemblies 810, the print blanket 302, and any other components of a LEP printer 800.

In this example, the controller 830 is also to control the system 100 for servicing print blankets. In particular, the processing resource 840 on the controller 830 executing control instructions 860 is to control the operative the elements of LEP printer 800 to cause a transfer of a portion of residue thermoplastic print agent from the print blanket 302 to the ECS 102 as the print blanket and ECS are rotated, with contact, in opposition to one another.

The processing resource 840 on the controller 830 executing control instructions 860 to control the operative the elements of LEP printer 800, e.g., by controlling rotation of the ECS 302 to contact the doctor blade 104, is to cause a scraping of a portion of the thermoplastic print agent from the rotating ECS 102. The doctor blade 104 is positioned adjacent to the ECS 102 to cause the portion of thermoplastic print agent to move into the container 108.

Continuing with the example of FIG. 8, the processing resource 840 on the controller 830 executing control instructions 860 to control the operative the elements of LEP printer 800 (e.g., heating element 106) to cause heating of the container such that thermoplastic print agent therein does not solidify.

The processing resource 840 on the controller 830 executing control instructions 860 to control the operative the elements of LEP printer 800 (e.g., by controlling rotation of the ECS 302) tis to cause the heated thermoplastic print agent in the container 108 to be picked up by the ECS 102 as the ECS is rotated adjacent to opening (e.g., an opening such as opening 310 FIG. 3) of the container 108.

In certain examples, the processing resource 840 on the controller 830 executing control instructions 860 to is control the operative the elements of LEP printer 800 (e.g., by controlling rotation of the ECS 302) to cause the doctor blade 104 to scrape the ECS 102 concurrent with the ECS 102 rotating to clean the print blanket 302. In certain examples, the controller 830 is to cause the doctor blade 104 to scrape the ECS 102 concurrent with the print blanket 302 being utilized in a printing operation (e.g., the print blanket 302 rotating receiving a thermoplastic print agent from the photoconductive surface 802 or the print blanket 302 transferring thermoplastic print agent to the print substrate 820).

FIG. 9 is a simple schematic diagram illustrating another example of a LEP printer implementing a system to service a print blanket. The example of a print blanket service system 100 illustrated at FIG. 9 is substantially similar to the system as described with respect to FIG. 8. In this example the print blanket 302a to be serviced is in the form of a belt, rather than being disposed upon a drum 816 as in FIG. 8. In examples, the print blanket may be in the form of an endless belt. In other examples, the print blanket may be otherwise disposed upon, or attached, to a belt.

In the example of FIG. 9 print blanket 302a is positioned to engage multiple photoconductive surfaces 802a-802d, rather than a single photoconductive surface 802 as presented in FIG. 8. In this example, each of the photoconductive surfaces 802a-802d is positioned to engage with a respective set of two developer assemblies 810a-810d, and has a dedicated imaging assembly 806a-806d and charging elements 804a-804d. In other examples, the sets of developer assemblies may be sets of one developer assembly or sets of more than two developer assemblies. In examples, each of the photoconductive surfaces 802a-802d may engage with a set of developer assemblies where not all of the sets have the same number of developer assembles.

Each instance of the combination of developer assembly, an imaging assembly, a photoconductive surface, and a charging element may be referred to as an “imaging engine.” With this FIG. 9 example architecture having four inline imaging engines with photoconductive surfaces 802a-802d engaged with a single blanket belt 302a, the LEP printer 900 is capable of printing up to four separations, e.g., four colors, with a single revolution of the blanket belt 302a at a continuous process speed. In other examples, LEP printer 900 may have more or less inline imaging engines.

According to the example of FIG. 9, a pattern of electrostatic charge is formed on each of the photoconductive surfaces 802a-802d by rotating a clean, bare segment of the photoconductive surface under its respective charging element 804a-804d.

Continuing with the example of FIG. 9, during a single revolution of the print blanket 302a print fluid is successively transferred from each of the photoconductive surfaces 802a-802d to print blanket 302a. Separations, e.g., color separations, are transferred to the print blanket 302a during the relative rotations of the print blanket 302a and the photoconductive surfaces 802a-802d. In the example of FIG. 9, the print blanket belt 302a rotates in the direction of arrow 818. The transfer of a developed image from each of the photoconductive surfaces 802a-802d to the print blanket belt 302a are successive “first transfers”, which takes place at a point of engagement between each of the photoconductive surfaces 802a-802d and the print blanket belt 302a.

Once the layers of print fluid have been transferred to the print blanket belt 302a (via a “first transfer” from each of the photoconductive surfaces 802a-802d), the layers are next transferred to a print substrate. In this example, print substrate 820 is a web substrate moving along a substrate path in a first substrate path direction 822a, and then in a second substrate path direction 822b. In other examples, the print substrate may a sheet substrate that travels along a substrate path. This transfer from the print blanket belt 302a to the print substrate 820 may be deemed the “second transfer”, which takes place at a point of engagement between the print blanket belt 302a and the print substrate 820. The impression cylinder 808 can both mechanically compress the print substrate 820 into contact with the print blanket 302a and also help feed the print substrate 820.

In this example the LEP printer includes a system 100 for servicing print blankets utilizing thermoplastic print agent that is similar to the example system 100 of FIG. 3 in that it includes the rotatably mounted ECS 102, a doctor blade 104, a heating element 106, and a container 108. In other examples the system 100 may include a containment blade (e.g., a containment blade such as containment blade 210 FIGS. 2, 4, 6), and/or a liquid level sensor (e.g., a liquid level sensor such as sensor 720 of FIGS. 7A and 7B).

Continuing with the example of FIG. 9, controller 930 represents the processing and memory resources and the programming, electronic circuitry and components needed to control the operative elements of LEP printer 900. Controller 930 may include distinct control elements for individual printer components. In the example shown in FIG. 8, controller 930 includes a processing resource 940 and a computer readable medium 950