WO2018199887A1

WO2018199887A1 - Pressure regulation unit

Info

Publication number: WO2018199887A1
Application number: PCT/US2017/029110
Authority: WO
Inventors: Tian Cheng Tang; Cherng Linn Teo
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2017-04-24
Filing date: 2017-04-24
Publication date: 2018-11-01

Abstract

The subject matter discloses examples of pressure regulation units for a printing system. In an example, the pressure regulation unit comprises an input port at a bottom end of the pressure regulation unit for receiving ink from an ink reservoir of the printing system. An output port is provided at a top end of the pressure regulation unit for transferring the ink to a printhead of the printing system. Further, a porous member is placed in between the input port and the output port to allow the ink to flow through an entire length of the porous member to reach the output port. The porous member is to be saturated during operation of the printing system to provide resistance to the ink flow from input port to the output port.

Description

PRESSURE REGULATION UNIT

BACKGROUND

[0001] Printing systems include a printhead for printing a print object on a print media and ink cartridges or reservoirs for providing ink to the printhead. The ink reservoir includes at least one outlet connected to the printhead for allowing the ink to flow to the printhead. Further, to avoid a condition of ink drooling, i.e., unintended ink discharge from the printhead nozzles, generally, a predetermined value of backpressure is maintained across printhead nozzles. For maintaining the backpressure, pressure regulation techniques are used in the printing systems.

BRIEF DESCRIPTION OF DRAWINGS

[0002] The detailed description is described with reference to the accompanying figures, it should be noted that the description and figures are merely example of the present subject matter and are not meant to represent the subject matter itself.

[0003] Figure 1 illustrates a pressure regulation unit, according to an example implementation of the present subject matter.

[0004] Figure 2 illustrates a printing system having a pressure regulation unit, according to an example implementation of the present subject matter. [0005] Figure 3 illustrates a printing system having a pressure regulation unit, according to another example implementation of the present subject matter.

[0006] Figure 4 illustrates a printing system having a pressure regulation unit, according to yet another example implementation of the present subject matter.

[0007] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

DETAILED DESCRIPTION

[0008] Printing systems use pressure regulation techniques to maintain a negative pressure across printhead nozzles. One such technique discloses use of a pressure regulation unit along the printhead to provide backpressure to the printhead. The pressure regulation unit may be provided as a part of an ink supply unit which may be installed in the printhead. The ink supply unit may include two chambers, one holding a porous member and another holding ink. The porous member is partially filled with ink and as the ink is drawn away from the porous member into the printhead, the pressure inside the chamber containing the porous member becomes negative and starts drawing air from an ink supply vent hole to replace volume of the ink drawn out. As the ink is drawn out of the ink supply unit to the printhead, the porous member may initially partially release its ink owing to which ink level in the porous member may decrease. Once a predefined amount of ink of the porous member has been used up, air may make its way to a bubbler point connecting the two chambers. As the air bubbles into the ink chamber, the pressure in the chamber with ink is relieved, and ink is drawn into the chamber with porous member and to the printhead. [0009] In said technique, the porous member may be partially saturated and partially unsaturated. As the porous member has to be partially saturated to facilitate the pressure regulation, a controlled amount of ink is used to soak the porous member. Thus, the pressure regulation unit is prefilled with ink in the factory and made leak proof by sealing fluidic interconnects with a stopper and a vent hole with a sticker label. The overall cost of the ink supply unit and the printing systems' may thus increase.

[0010] Example implementations for a pressure regulation unit are described. As per an example of the present subject matter, the pressure regulation unit is to be placed between an ink reservoir and a printhead of a printing system for generating dynamic backpressure across the printhead. In said approach, the pressure regulation unit includes a porous member as a flow restrictor for restricting flow of ink through the pressure regulation unit for generating the backpressure. The porous member is saturated, owing to which the ink flowing through the porous member may face a resistance, thus generating backpressure. The pressure regulation unit with a saturated porous member thereby facilitates backpressure generation at the printhead during operation of the printing system.

[0011] in one example, the pressure regulation unit is to be connected in between the ink reservoir and the printhead. The pressure regulation unit includes a chamber having an input port at a bottom end for receiving ink from the ink reservoir. Further, an output port is provided at a fop end of the chamber of the pressure regulation unit for transferring the ink to the printhead. The porous member is placed in between the input port and the output port such that the ink flows through an entire length of the porous member to reach the output port for transfer to the printhead. As the porous member is in a saturated state during operation of the printing system, the ink flow from input port to the output port is constrained. Having the porous member in a saturated state to restrict the ink flow, facilitates backpressure generation at the printhead during operation of the printing system. [0012] The present subject matter thus facilitates in providing backpressure across the printhead nozzles during operation of the printing system. Having the saturated porous member as a flow restricfor helps in providing a cost effective and less complex technique for maintaining negative pressure to prevent ink drooling. Further, as the porous member may be automatically saturated with ease, and without user interference, once the printing system is installed and switched ON at a user location, the pressure regulation unit may be preinstalied in the printing system and shipped dry. Having the pressure regulation unit shipped in a dry state facilitates in reducing certain components previously used for making the pressure regulation units leak proof during shipping. Reducing the number of components makes the current pressure regulation unit cost effective and easier to install and maintain. Further, in comparison to the previous techniques, where backpressure is only generated by raising the printhead relative to ink tank bubbler point height, height difference between the printhead positioning and the ink reservoir may be reduced owing to the use of the pressure regulation unit for backpressure generation during operation, thus optimizing the space utilization for the printing system.

[0013] The present subject matter is further described with reference to Figures 1 to 4. it should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0014] Figure 1 illustrates a pressure regulation unit 100 for a printing system, according to an example implementation of the present subject matter.

In one implementation, the pressure regulation unit 100 is provided to generate backpressure at a printhead (not shown in this figure) of the printing system (not shown in this figure). The pressure regulation unit 100 includes a chamber 102 having an input port 104 at a bottom end and an output port 106 at a top end. The input port 104 is provided at the bottom end of the chamber 102 for receiving ink from an ink reservoir (not shown in this figure) of the printing system. The output port 106 is provided at the top end of the chamber 102 of the pressure regulation unit 100 for transferring the ink to the printhead of the printing system.

[001 S] The pressure regulation unit 100 further includes a porous member 108 placed in between the input port 104 and the output port 106. In one example, the porous member 108 is placed in the chamber 102 of the pressure regulation unit 100 to allow the ink to flow through an entire length of the porous member 108 to reach the output port 106. In one example implementation, the porous member 108 is to be saturated during operation of the printing system to provide resistance to the ink flow from input port 104 to the output port 106.

[0016] Figure 2 illustrates a printing system 202 having the pressure regulation unit 100, according to an example implementation of the present subject matter. In one example, the printing system 202 includes an ink reservoir 204, a printhead 206, and the pressure regulation unit 100, The printhead 206 is to print a print object on a print media, while the ink reservoir 204 is to hold ink for printing. The pressure regulation unit 100 is provided in between the ink reservoir 204 and the printhead 206 for generating dynamic backpressure at the printhead 206. in one example, the pressure regulation unit 100 is to receive ink from the ink reservoir 204 and transfer the ink to the printhead 206.

[0017] in one example implementation of the present subject matter, the pressure regulation unit 100 includes the chamber 102 having the porous member 108 to generate dynamic backpressure during operation of the printing system 202. The porous member 108 is positioned such that the ink received in the pressure regulation unit 100 from the ink reservoir 204 is to flow through an entire length of the porous member 108 for transfer to the printhead 206. in one example, the porous member 108 is to be saturated during operation of the printing system 202 to generate dynamic backpressure by providing resistance to the ink flow from the ink reservoir 204 to the printhead 206.

[0018] Figure 3 illustrates a printing system having a pressure regulation unit, according to another example implementation of the present subject matter. In one example, the printing system 202 includes the ink reservoir 204, the printhead 206, and the pressure regulation unit 100. The ink reservoir 204 is to hold ink to be used by the printhead 206 to print a print object on a print media. The pressure regulation unit 100 is connected to the printhead 206 and the ink reservoir 204 to resist the ink flow from the ink reservoir 204 to the printhead 206 for generating dynamic backpressure at the printhead 206.

[0019] in one example, the pressure regulation unit 100 includes the chamber 102, having the porous member 108 placed in between the input port 104 and the output port 106 of the chamber 102 of the pressure regulation unit 100. Having the porous member 108 placed in between the input port 104 and the output port 106 allows the ink received from the input port 104 to flow through an entire length of the porous member 108 to reach the output port 106. in one example implementation, the porous member 108 is to be saturated during operation of the printing system 202 to resist the ink flow to generate back pressure at the printhead 206.

[0020] Figure 4 illustrates the printing system 202 having the pressure regulation unit 100, according to yet another example implementation of the present subject matter. In one example, the printing system 202 includes the ink reservoir 204, the printhead 206, the pressure regulation unit 100, a pump assembly 402, and a service station cap 404. As previously described, the printhead 206 is provided to print a print object on a print media. To print, the printhead 206 is supplied ink from the ink reservoir 204, holding a predetermined amount of ink.

[0021] The printhead 206 is further connected to the service station cap 404 and the pump assembly 402. The pump assembly 402 and the service station cap 404 are provided to create suction at the printhead 206 for drawing ink into the printhead 206 from the ink reservoir 204 through the pressure regulation unit 100 during operation of the printing system 202. In one example, the pump assembly 402 may include a plurality of pumps connected to different nozzles of the printhead.

[0022] The pressure regulation unit 100 is connected in between the printhead 206 and the ink reservoir 204. As illustrated, the pressure regulation unit 100 is connected to the ink reservoir 204 and the printhead 206 using a first connection 406-1 and a second connection 406-2, respectively. The first connection 406-1 and the second connection 406-2, are collectively referred to as connections 406. In one example, the first connection 406-1 connects the input port 104 of the chamber 102 of the pressure regulation unit 100 to the ink reservoir 204, The second connection 406-2 connects the output port 106 of the chamber 102 of the pressure regulation unit 100 to the printhead 206.

[0023] The pressure regulation unit 100 includes the input port 104 at a bottom end of the chamber 102 for receiving ink from the ink reservoir 204. in one example, the input port 104 may be provided on a bottom wall of the chamber 102 of the pressure regulation unit 100, as illustrated in Figure 4. in another example, the input port 104 may be provided on a side wail at the bottom end of the chamber 102 of the pressure regulation unit 100. Further, the output port 106 is provided at a top end of the chamber 102 of the pressure regulation unit 100 for transferring the ink to the printhead 206. In one example, the output port 106 may be provided on a top wall of the chamber 102 of the pressure regulation unit 100, as illustrated in Figure 4. In another example, the output port 106 may be provided on a side wall at the top end of the chamber 102 of the pressure regulation unit 100.

[0024] The pressure regulation unit 100 further includes the porous member 108 placed in the chamber 102, in between the input port 104 and the output port 106, such that the ink flows through an entire length of the porous member 108 to reach the output port 106 before being transferred to the printhead 206 via the second connection 406-2. in one example, the porous member 108 has a volume equal to an inner volume of the chamber 102 of the pressure regulation unit 100. Further, the length of the porous member 108 is equal to a distance between the input port 104 and the output port 106. Further, the width of the porous member 108 is equal to an inner width of the chamber 102 of the pressure regulation unit 100.

[002S] As previously described, the porous member 108 is in a saturated state during operation of the printing system 202 to restrict the ink flow from the input port 104 to the output port 106. Having the porous member 108 in a saturated state to restrict the ink flow, facilitates backpressure generation at the printhead 208 during operation of the printing system 202.

[0026] In one example implementation of the present subject matter, the pressure regulation unit 100 is manufactured and supplied with the porous member 108 in a dry state. The porous member 108 is thus saturated with the ink once the printing system 202 is installed and switched ON for the first time at a user location. In one example, once the printing system 202 is powered up, the service station cap 404 and the pump assembly 402 may create suction for drawing ink from the ink reservoir 204 into the pressure regulation unit 100 to saturate the porous member 108. Once the porous member 108 has been saturated and an entire ink delivery system and the printhead 206 is filled with ink, the operation of the printing system 202 may be initiated, in one example, the ink delivery system may include the connections 406, the pressure regulation unit 100, and the porous member 108. Having the pressure regulation unit 100 pre- installed in the printing system 202 and shipped in a dry state facilitates in reducing certain components previously used for making the pressure regulation units 100 leak proof during shipping.

[0027] Further, to provide additional backpressure during operation as well as to provide static backpressure required during idle condition of the printing system 202, the printhead 206 may be positioned at a height above a bubbler point of the ink reservoir 204. in comparison to the previous techniques, where backpressure is only generated by raising the printhead relative to ink tank bubbler point height, the printhead 206 may be positioned at a lesser height above the ink reservoir 204 owing to the use of the pressure regulation unit 100 for backpressure generation, thus reducing the space utilization by the position of the printhead 206 and in turn the printing system 202.

[0028] In operation, as the service station cap 404 and the pump assembly 402 create suction at the printhead 206, pressure differential is created at the pressure regulation unit 100 and the ink reservoir 204, drawing the ink from the ink reservoir 204. The ink moves from the ink reservoir 204 into the first connection 406-1 and enters the pressure regulation unit 100 through the input port 104. Upon entering the pressure regulation unit 100, the ink starts to flow through the porous member 108, which is in a saturated state. The porous member 108, thus resists the flow of the ink, thereby generating backpressure at the printhead 206. Upon flowing through the entire length of the porous member 108, under restricted flow, the ink exits the pressure regulation unit 100 through the output port 106. The ink then gets transferred to the printhead 206 through the second connection 406-2.

[0029] Although examples for the present subject matter have been described in language specific to structural features and/or methods, it should be understood that the appended claims are not limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present subject matter.

Claims

What is claimed is:

1 . A pressure regulation unit for a printing system comprising:

a chamber;

an input port at a bottom end of the chamber for receiving ink from an ink reservoir of the printing system;

an output port at a top end of the chamber for transferring the ink to a printhead of the printing system; and

a porous member placed in the chamber, in between the input port and the output port, to allow the ink to flow through an entire length of the porous member to reach the output port, wherein the porous member is to be saturated during operation of the printing system to provide resistance to the ink flow from input port to the output port.

2. The pressure regulation unit as claimed in claim 1 , wherein the porous member has a volume equal to an inner volume of the chamber, wherein length of the porous member is equal to a distance between the input port and the output port, and wherein a width of the porous member is equal to an inner width of the chamber of the pressure regulation unit,

3. The pressure regulation unit as claimed in claim 1 , wherein the porous member is to be saturated with ink upon installation of the printing system.

4. A printing system comprising:

a printhead to print a print object on a print media;

an ink reservoir to hold ink for the printing; and

a pressure regulation unit to generate dynamic backpressure at the printhead, wherein the pressure regulation unit includes a chamber to receive ink from the ink reservoir and transfer the ink to the printhead, the pressure regulation unit comprising:

a porous member to be saturated during operation of the printing system to generate dynamic backpressure by providing resistance to the ink flow from the ink reservoir to the printhead, wherein the ink received in the pressure regulation unit from the ink reservoir is to flow through an entire length of the porous member for transfer to the printhead.

5. The printing system as claimed in claim 6, wherein the pressure regulation unit comprises:

an input port at a bottom end of the chamber of the pressure regulation unit for receiving ink from the ink reservoir; and

an output port at a top end of the chamber of the pressure regulation unit for transferring the ink to the printhead.

8. The printing system as claimed in claim 5, wherein the porous member is placed in between the input port and the output port to allow the ink to flow through the entire length of the porous member to reach the output port.

7. The printing system as claimed in claim 8, wherein the porous member has a volume equal to an inner volume of the chamber, and wherein length of the porous member is equal to a distance between the input port and the output port, and wherein a width of the porous member is equal to an inner width of the chamber of the pressure regulation unit.

8. The printing system as claimed in claim 4, further comprising a pump assembly connected to the printhead to create suction at the printhead for drawing ink into the printhead from the ink reservoir through the pressure regulation unit during operation of the printing system.

9. The printing system as claimed in claim 8, wherein upon installation of the printing system, the pump assembly is to create suction for drawing ink from the ink reservoir into the pressure regulation unit to saturate the porous member.

10. The printing system as claimed in claim 9, wherein the porous member is to be saturated one time when the printing system is powered up for the first time after installation.

1 1 . The printing system as claimed in claim 4, wherein the printhead is positioned at a height above a bubbler point of the ink reservoir to generate backpressure.

12. A printing system comprising:

a printhead to print a print object on a print media;

an ink reservoir to hold ink for the printing; and

a pressure regulation unit having a chamber and connected to the printhead and the ink reservoir to resist the ink flow from the ink reservoir to the printhead, the pressure regulation unit comprising:

a porous member placed in between an input port and an output port of the chamber of the pressure regulation unit, such that the ink received from the ink reservoir at the input port flows across a length of the porous member to reach the output port, wherein the porous member is to be saturated during operation of the printing system to resist the ink flow to generate back pressure at the printhead.

13. The printing system as claimed in claim 12, wherein the pressure regulation unit further comprises:

the input port at a bottom end of the chamber of the pressure regulation unit for receiving ink from the ink reservoir; and the output port at a top end of the chamber of the pressure regulation unit for transferring the ink to the printhead.

14. The printing system as claimed in claim 12, wherein the printhead is positioned at a height above a bubbler point of the ink reservoir to generate the backpressure.

15. The printing system as claimed in claim 12, further comprising a service station cap and a pump assembly connected to the printhead to create suction for drawing ink from the ink reservoir into the pressure regulation unit to saturate the porous member once the printing system is powered up after installation.