developing roller

Abstract

A developer roller is disclosed, comprising: a first portion including a first outer surface, wherein the first outer surface comprises a conductive material; and a second portion including a second outer surface, wherein the second outer surface is non-conductive. The second portion is axially aligned with the first portion and provided at a first longitudinal end of the first portion.

Description

Technical Field

[0001] The present disclosure generally relates to developer rollers. Background Art

[0002] In electrostatic printers, a conductive developer roller is charged by electrodes within a binary ink developer. To enhance the transfer of printing fluid to and from the developer roller, a non-conductive coating is provided on the surface of the developer roller. As the coating dries on the surface, it may begin to retract from the longitudinal ends of the developer roller. This may expose the longitudinal ends of the developer roller surface to the electrodes. Subsequently, electrical breakdown (also known as arcing) may occur between the longitudinal ends of the surface and the electrodes, which may cause the developer roller to begin to melt and undergo gelation. This gelation may cause the printing fluid to splash during use, which may lead to undesirable inconsistencies in the printing process. Summary of the Invention

[0003] According to a first aspect of the present disclosure, a developing roller is provided, comprising: a first portion comprising a first outer surface, wherein the first outer surface comprises a conductive material; a second portion comprising a second outer surface, wherein the second outer surface is non-conductive; and a non-conductive coating provided on the first outer surface, wherein the second portion is axially aligned with the first portion and provided at a first longitudinal end of the first portion.

[0004] According to a second aspect of the present disclosure, there is provided a roller for use in an electrostatic printing device, the roller comprising: a conductive portion; non-conductive caps at longitudinal ends of the conductive portion; and a non-conductive layer on an outer surface of the conductive portion.

[0005] According to a third aspect of the present disclosure, there is provided a method for making a developer roller for a printing device, the method comprising: attaching a non-conductive cap to a conductive element so that the conductive element and the non-conductive cap are axially aligned to form a subassembly; and providing a non-conductive coating on an outer surface of the subassembly, the outer surface being partially defined by the conductive element and partially defined by the non-conductive cap. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The various features of the present disclosure will be apparent from the following detailed description taken in conjunction with the accompanying drawings. Figure 1 The following illustrates features of the present disclosure, and wherein:

[0007] Figure 1 A schematic view of an example image development unit is shown.

[0008] Figure 2 A schematic view of an example developer roller is shown.

[0009] Figure 3 Shown Figure 1 A schematic close-up view of a portion of the developer roller.

[0010] Figure 4 A schematic view of an example cap is shown.

[0011] Figure 5 A schematic view of an example cap mold is shown.

[0012] Figure 6 A flow chart of an example method is shown. DETAILED DESCRIPTION

[0013] In some liquid electrophotographic printers, a transfer element is used to transfer a developed liquid printing fluid (e.g., ink) to a print medium. For example, a developed image comprising the liquid printing fluid aligned with a latent image can be transferred from a photo imaging plate (PIP) to a transfer blanket on a transfer drum, and from the transfer blanket to a desired substrate placed in contact with the transfer blanket. At least two different approaches can be used to print multicolor images in liquid electrophotographic printers. Both approaches involve the generation of multiple color separations, each of which is a single-color partial image. When these color separations are superimposed, the desired full-color image can be formed. In the first approach, a color separation layer is generated on the PIP, transferred to a transfer drum, and ultimately transferred to the substrate. Subsequent color separation layers are similarly formed and successively transferred to the substrate on top of the previous layer(s). This is sometimes referred to as a "multi-shot color" imaging sequence. In the second approach, a "one-shot color" process is used. In these systems, the PIP transfers a series of color separations to a transfer blanket on a transfer drum, building each color separation layer on the blanket. Once a certain number of color separations are formed on the transfer blanket, they are all transferred to the substrate together. Both methods result in the formation of a full-color image.

[0014] In some electrophotographic printers, an image development unit (such as a binary ink developer (BID)) contains a printing fluid (e.g., liquid ink) to be transferred to the PIP. The liquid ink comprises ink particles and a carrier fluid. More than one image development unit may be used, each containing a different color of printing fluid. The printing fluid or pigment particles are electrically charged and can be arranged on the PIP based on the charge pattern of the latent image. Once the liquid printing fluid is applied to the latent image on the PIP, an image is formed on the PIP. When the printing fluid is ink, the image comprises ink particles aligned according to the latent image.

[0015] Figure 1 An example image development unit 100 is shown. Figure 1 The image developing unit 100 is part of an electrophotographic printer and is removably connected or connectable to the PIP 101. Figure 1As shown in FIG, the image developing unit 100 is in the form of a BID 100, including a developing roller 1 (eg, Figure 2 ), which contacts PIP 101 to transfer printing fluid (eg, ink) during printing. In other examples, image development unit 100 may take different forms.

[0016] Figure 2 An example developing roller (or rollers) 1 is shown. The developing roller 1 is used to Figure 1 In the image developing unit 100. Figure 1 and Figure 2 Like reference numerals in the drawings indicate like features. The developing roller 1 comprises a first portion 2 and a second portion 3. Figure 2 In the example shown in , the first portion 2 and the second portion 3 are cylindrical. The first portion 2 includes a first outer surface 4, which includes a conductive material. In some examples, the first portion 2 is also referred to as a conductive portion. The second portion 3 includes a second outer surface 5, wherein the second outer surface 5 is non-conductive. For example, the second outer surface 5 is made entirely of a non-conductive material. Figure 2 In the example shown in , the first outer surface 4 and the second outer surface 5 are the circumferential surfaces of the first portion 2 and the second portion 3, respectively. In some examples, the second portion 3 is also referred to as a non-conductive cap. Figure 2 In some examples, the second outer surface 5 comprises a non-conductive material. In other examples, the second portion 3 is made entirely of a non-conductive material. Figure 2 In some examples, the non-conductive material is polyurethane or rubber. In other examples, other non-conductive materials are used. Figure 2 As shown in FIG, the second portion 3 is axially aligned with the first portion 2 and is provided at a first longitudinal end 6 of the first portion 2 .

[0017] exist Figure 2 In the example shown in FIG, the developing roller 1 comprises a third portion 7 which is axially aligned with the first portion 2 and provided at a second longitudinal end 8 of the first portion 2. In this way, the first portion 2 can be considered as an intermediate portion. The third portion comprises a non-conductive third outer surface 9. Figure 2 In the example of , the third portion 7 is the same as the first portion 2. For example, the third portion 7 has the same size as the second portion 3 and includes the same material as the second portion 3. In other examples, the third portion 7 has different properties from the second portion 3. For example, the third portion 7 may include a different material than the second portion 3 or have a different size than the second portion 3. In some examples, the third portion 7 is also referred to as a non-conductive cap. Figure 2As shown in FIG, the second portion 3 at least partially defines a first longitudinal end 16 of the developing roller 1. The third portion 7 at least partially defines a second longitudinal end 17 of the developing roller 1. The second longitudinal end 17 of the developing roller 1 is opposite to the first longitudinal end 16 of the developing roller 1. Alternatively, the third portion 7 is omitted.

[0018] exist Figure 2 In the example shown in FIG, first part 2 is formed on second part 3. For example, second part 3 is formed in a mold (as discussed later), and the first part is subsequently formed on second part 3. For example, once second part 3 is formed, first part 2 can be applied to second part 3 in a non-solid form, such that when first part 2 solidifies, first part 2 is attached to second part 3. In this example, first part 2 is formed on third part 7 in the same manner. In other examples, first part 2 is attached to second part 3 and third part 7 in any other suitable manner. For example, an adhesive can be used to attach first part 2 to second part 3 and third part 7. In some examples, first part 2 and / or third part 7 are formed on second part 3. In some examples, when first part 2 is formed on second part 3 or third part 7, there may be mixing of materials between first part 2 and second part 3 or between first part 2 and third part 7. Such mixing may occur due to diffusion of materials from the respective parts before the respective parts have fully solidified.

[0019] Figure 3 Shown Figure 2 A close up view of a portion of the developing roller 1. Figure 3 As shown in FIG, the developer roller 1 includes a non-conductive coating 15 (or layer) on a first outer surface 4 and a second outer surface 5. Figure 2 In the example shown in , the coating 15 is also provided on the third outer surface 9. In other examples, the coating 15 is provided on at least the first outer surface 4. For example, in some examples, the coating 15 is provided on the first outer surface 4, but not on the second outer surface 5 or the third outer surface 9. In other examples, the coating 15 is provided on the first outer surface 4 and on at least a portion of the second outer surface 5 and / or on at least a portion of the third outer surface 9. Figure 2 and 3 In the example of , coating 15 comprises polyurethane. In other examples, coating 15 comprises any other suitable material. Figure 3In the example shown in , the coating 15 is retracted from the first longitudinal end 16 and the second longitudinal end 17 of the developer roller 1. In other examples, the coating 15 extends completely across the second outer surface 5 to the first longitudinal end 16 of the developer roller 1. The coating 15 helps release the printing fluid from the developer roller 1 and also helps control the conductivity of the developer roller 1. For example, the coating 15 has a formulation that includes ingredients that balance the adhesion and release of the printing fluid. In some examples, the conductivity of the developer roller 1 is determined by the thickness of the coating 15. Figure 2 and 3 In the example shown in , the coating 15, the second outer surface 5, and the third outer surface 9 together define the entire circumferential surface of the developer roller 1. In other examples where the coating 15 completely covers the first outer surface 4, the second outer surface 5, and the third outer surface 9 (i.e., extends from the first longitudinal end 16 of the developer roller 1 to the second longitudinal end 17 of the developer roller 1), the coating 15 defines the entire circumferential surface of the developer roller 1.

[0020] As discussed above, when the coating 15 applied to the developer roller 1 dries, it may retract from the longitudinal ends 16, 17 of the developer roller 1. Figure 3 As shown in , this exposes a portion of the second outer surface 5 to the circumferential surface of the developer roller 1 during use. However, because the second outer surface 5 is non-conductive, when the developer roller 1 is provided in an electrostatic printing device, arcing is less likely to occur between the electrodes of the printing device and the second outer surface 5. Thus, the second outer surface 5 is less likely to soften and melt during use, and the chance of gelation is reduced, thereby improving the printing consistency of the printing device. As discussed above with respect to the second outer surface 5, the same effect can also occur at the third outer surface 9.

[0021] like Figure 2 As shown in FIG, the developing roller 1 includes a rod 10 passing through the center of each of the first portion 2, the second portion 3, and the third portion 7. Figure 1 In the example shown in , the developer roller 1 is intended to rotate about the longitudinal axis of the rod 10 in use.

[0022] In some examples, such as the present example, the first outer surface 4, the second outer surface 5, and the third outer surface 9 (when provided) comprise the same substrate. For example, the first outer surface 4, the second outer surface 5, and the third outer surface 9 comprise rubber or polyurethane. In this example, the first outer surface 4 also comprises a conductive material, while the second outer surface 5 and the third outer surface 9 are substantially free of conductive material. In other examples, the first outer surface 4, the second outer surface 5, and the third outer surface 9 comprise any other suitable material.

[0023] Figure 4An example of the second portion 3 (or cap) discussed above is shown before any processing of the second outer surface 5 has occurred. The second portion 3 includes a hole 11 to receive the rod 10. The second outer surface 5 of the second portion 3 is non-conductive. In some examples, the second portion 3 is made entirely of a non-conductive material. In other examples, the second outer surface 5 is non-conductive, while a portion of the second portion 3 distal to the second outer surface 5 is conductive. The third portion 7 is substantially identical to the second portion 3 and has the same properties as discussed above.

[0024] Figure 5 Shown for forming Figure 2 The mold 12 of the second part 3 (or cap) is shown in FIG. Figure 5 As shown in , the use of the mold 12 allows the second part 3 (or end cap) to be pre-produced separately from the first part 2. Figure 5 As shown in FIG, the mold 12 includes a space 13 into which the material for forming the second portion 3 is inserted. Figure 5 The space 13 shown in FIG has an elongated "D" profile, but other shaped profiles may also be used. In one example, the space 13 has a circular profile. The mold 12 also includes a shaped protrusion 14 corresponding to the hole 11 of the second part 3. In some examples, such as Figure 5 The mold 12 shown in FIG. 1 is also used to form the third part 7 .

[0025] Although the use of a mold 12 to form the second portion 3 is discussed above, in other examples, other manufacturing methods are used. In some examples, the second portion 3 and / or the third portion 7 are formed using a three-dimensional printer. In other examples, other forms of computer-aided manufacturing can be used, such as using a computer numerical control (CNC) machine.

[0026] Figure 6 A flow chart is shown of a method 20 for making a developer roller 1 for a printing device according to one example. The method 20 includes attaching 21 a non-conductive cap to a conductive element such that the conductive element and the cap are axially aligned to form a subassembly. The method 20 also includes providing 22 a non-conductive coating on an outer surface of the subassembly, the outer surface being defined in part by the element and in part by the cap.

[0027] In some examples, the subassembly is Figure 2 The developer roller 1 (or roller) is described. For example, the conductive element is equivalent to the first portion 2, and the cap is equivalent to the second portion 3 and / or the third portion 7.

[0028] like Figure 6 As shown in , the method 20 also includes treating 23 the outer surface of the subassembly to create a substantially uniform surface. In this example, the treating 23 occurs before providing 22 the non-conductive coating. Figure 6In the example of , processing 23 comprises grinding the outer surface so that the subassembly has a substantially circular cross-section. In other examples, other processes that produce a substantially circular cross-section of the subassembly, such as milling or filing, may be used. Figure 2 The developing roller 1 shown in FIG has a generally cylindrical shape with a circular cross section. Figure 2 In the example of FIG, the developer roller 1 is initially formed with a non-circular cross section and is processed to have a circular cross section by, for example, grinding the first outer surface 4, the second outer surface 5, and the third outer surface 9. In other examples, the developer roller 1 is formed with a circular cross section without requiring further processing to change the cross-sectional shape of the developer roller 1.

[0029] As discussed above, the first portion 2, the second portion 3, and the third portion 7 comprise the same substrate. A conductive material is added to the first outer surface 4, making the first outer surface 4 conductive. No conductive material is added to the second outer surface 5 and the third outer surface 9, making the second outer surface 5 and the third outer surface 9 non-conductive.

[0030] like Figure 1 As shown in , the image developing unit 100 includes a developer roller 1 (or rollers) as discussed in any of the examples above. In some examples, the image developing unit 100 is a binary ink developer. In other examples, a printing device (such as a liquid electrophotographic printer) includes the image developing unit 100.

[0031] As discussed in the examples above, a developer roller 1 (or roller) is provided that helps reduce the chance of the developer roller 1 melting during use by providing portions of non-conductive material at the longitudinal ends 16, 17 of the developer roller 1. The non-conductive portions reduce the chance of arcing between the electrode and the developer roller 1 during use, thereby reducing changes in the melting of the developer roller 1. This helps reduce the chance of the developer roller 1 becoming damaged, thereby increasing the life of the developer roller 1, while also improving print quality and / or consistency.

[0032] The foregoing description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. In light of the above teachings, many modifications and variations are possible. It should be understood that any feature described with respect to any example may be used alone or in combination with other features described, and may also be used in combination with any feature of any other example, or with any feature of any combination of any other examples.

Claims

1. A developing roller comprising: a first portion comprising a first exterior surface, wherein the first exterior surface comprises an electrically conductive material; a second portion comprising a second outer surface, wherein the second outer surface is non-conductive; and providing a non-conductive coating on the first outer surface, said non-conductive coating also being provided on at least a portion of said second outer surface, The second portion is axially aligned with the first portion and is provided at a first longitudinal end of the first portion. 2 . The developer roller of claim 1 , wherein the second outer surface comprises polyurethane.

3. The developer roller of claim 1, wherein the non-conductive coating comprises polyurethane. The developer roller according to claim 1 , wherein the second portion is entirely made of a non-conductive material.

5. The developer roller of claim 1, wherein the second portion at least partially defines a first longitudinal end of the developer roller.

6. The developer roller of claim 1 , comprising a third portion comprising a third outer surface, wherein the third outer surface is non-conductive, and wherein the third portion is axially aligned with the first portion and provided at a second longitudinal end of the first portion, opposite the first longitudinal end of the first portion.

7. A developer roller according to claim 5, comprising a third portion, wherein the third portion is axially aligned with the first portion and is provided at a second longitudinal end of the first portion, opposite to the first longitudinal end of the first portion, and wherein the third portion at least partially defines the second longitudinal end of the developer roller, opposite to the first longitudinal end of the developer roller.

8. A roller for use in an electrostatic printing device, the roller comprising: Conductive part; non-conductive caps at longitudinal ends of the conductive portion; and A non-conductive layer is provided on the outer surface of the conductive portion, the non-conductive layer also being provided on at least a portion of the outer surface of the non-conductive cap.

9. The roller of claim 8, wherein the non-conductive cap defines a portion of the outer surface of the roller.

10. An image developing unit comprising the roller according to claim 8.

11. A method for manufacturing a developing roller for a printing device, the method comprising: attaching the non-conductive cap to the conductive element such that the conductive element and the non-conductive cap are axially aligned to form a subassembly; and A non-conductive coating is provided on an outer surface of the subassembly, the outer surface being defined in part by the conductive element and in part by the non-conductive cap, wherein the non-conductive coating is provided on at least a portion of the conductive element and the non-conductive cap.

12. The method of claim 11, comprising treating an outer surface of the subassembly to create a substantially uniform surface.

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