Pressure regulating valve with dual valve member

Abstract

A pressure regulating valve for an inkjet printhead is disclosed. The valve includes a valve inlet connected to a valve outlet, a fluid flow path, a first orifice positioned in the flow path having a sealable first seat, a moveable first valve member configured for sealing engagement with the first seat, a second orifice positioned in the flow path, a moveable second valve member configured for regulating fluid flow rate through the second orifice, a regulating chamber having the valve outlet and including a diaphragm operatively connected to the second valve member such that movement of the diaphragm moves the second valve member relative to the second orifice, and a biasing mechanism for resiliently biasing the diaphragm away from the second orifice.

Description

Invention Field

[0001] This invention relates to a pressure regulating valve for controlling the pressure at an inkjet printhead. This pressure regulating valve is primarily developed to supply ink to the inkjet printhead at a relatively constant pressure and to reduce the cost of the ink delivery system. Background of the Invention

[0002] Inkjet printers using Memjet® technology are commercially available for many different printing formats, including printers for home office (“SOHO”) use, label printers, and wide-format printers. ® Printers typically include one or more fixed inkjet printheads that are user-replaceable. For example, SOHO printers include a single user-replaceable multicolor printhead, high-speed inkjet printers include multiple user-replaceable monochrome printheads aligned along the media feed direction, and wide-format printers include multiple user-replaceable printheads arranged in an overlapping manner to span the width of a wide page.

[0003] As the number of printheads increases, supplying ink to multiple printheads can become problematic. To maintain high print quality, each printhead should receive ink from a shared ink reservoir at approximately the same ink pressure.

[0004] US Patent 10,252,540 describes an ink delivery system for a digital inkjet printer with multiple printheads, the contents of which are incorporated herein by reference. This system uses overall pressure control in a shared ink delivery module and local fine pressure control in each print module containing the respective printheads. Due to the high ink flow requirements of multiple inkjet printheads and the need to control the pressure in both positive and negative pressure ink lines, two diaphragm pumps are required to control the ink pressure in the ink delivery module. These diaphragm pumps are necessarily large, high-quality pumps operating in combination with local electronically controlled pressure regulators in each print module. Consequently, the ink delivery system is an expensive system due to the high cost of these two diaphragm pumps and the electronically controlled pressure regulators in each print module.

[0005] For inkjet printing systems with a small number of printheads (e.g., one or two printheads), expensive ink delivery modules designed for larger systems are undesirable and significantly increase the overall system cost. U.S. Patent Application No. 17 / 180,401, filed February 19, 2021, describes an ink delivery module suitable for inkjet printing systems with a small number of printheads. This ink delivery module uses a low-cost air pump in conjunction with a flow limiter as a device for regulating the pressure in the ink supply tank and ink return tank, which are connected to the ink supply line and ink return line, respectively.

[0006] Passive pressure regulating valves have been proposed as suitable devices for controlling ink pressure in inkjet printing systems. For example, US 7,712,880 (granted to Memjet Technology Ltd) describes a pressure regulating valve with a diaphragm and a biasing mechanism that cooperate to open the valve member in response to changes in ink pressure and to seal the valve member against a valve seat. US 7,862,138 (granted to Hewlett-Packard Development Company, LP) describes a pressure regulating valve that operates on a similar principle: a biased diaphragm is connected to the valve member via a lever mechanism to seal the orifice closed or open.

[0007] The advantages of pressure regulating valves are low cost and localized pressure control near the printhead. However, the disadvantages of the valves described in the prior art are hysteresis caused by the sealing of the orifice and pressure fluctuations. Furthermore, high flow rates cannot be easily achieved via the on / off valve.

[0008] Therefore, it is desirable to provide a low-cost device for regulating ink pressure, which at least improves some of the disadvantages of the aforementioned prior art pressure regulation systems. Invention Overview

[0009] In a first aspect, a pressure regulating valve for an inkjet printhead is provided, the valve comprising:

[0010] Entry port;

[0011] Export port;

[0012] A fluid flow path that is defined between an inlet port and an outlet port;

[0013] A first orifice, the first orifice being positioned in the flow path, the first orifice having a sealable first seat;

[0014] A movable first valve member configured for sealing engagement with a first seat;

[0015] A second orifice, which is located in the flow path;

[0016] A movable second valve component configured to regulate the fluid flow rate through a second orifice;

[0017] A regulating chamber having an outlet port and including a diaphragm operatively connected to a second valve member, such that movement of the diaphragm causes movement of the second valve member relative to a second orifice; and

[0018] A biasing mechanism for elastically biasing the diaphragm away from the second orifice.

[0019] The advantage of the pressure regulating valve according to the first aspect is that it controls the fluid flow to the printhead without requiring the valve component to act as a shut-off valve during the printhead's idle period. Advantageously, the shut-off function is handled by an actuated (e.g., solenoid-actuated) first valve component, while the pressure regulating function is handled by a second valve component controlled by a diaphragm that does not have a sealing or shut-off function.

[0020] Preferably, the second orifice is located downstream of the first orifice.

[0021] Preferably, the first valve component includes a compliant plug for sealing engagement with the first seat.

[0022] Preferably, the first valve member is operatively connected to an actuator (such as a solenoid) for opening and sealingly closing the first orifice. Typically, when the solenoid is de-energized, the first valve member seals against the first orifice.

[0023] Preferably, the biasing mechanism includes a spring operatively connected to the diaphragm, wherein the spring biases the second valve member toward closing the second orifice.

[0024] Preferably, in use, the diaphragm and spring cooperate to passively control the flow rate through the second orifice. For example, a decrease in pressure in the regulating chamber causes the diaphragm to contract toward the second orifice, thereby tending to move the second valve member toward opening the second orifice. Simultaneously, the contraction of the diaphragm is offset by the bias of the spring, thereby providing passive regulation of the flow rate through the second orifice via force balance between the diaphragm and the spring.

[0025] Preferably, the second valve member and the second orifice have rigid mating surfaces. Rigid mating surfaces (e.g., metal, rigid plastic, etc.) are typically non-sealed to prevent surface adhesion during use and to avoid pressure management lag.

[0026] Preferably, the movement of the diaphragm toward the second orifice gradually opens the second orifice, thereby increasing the flow rate through the second orifice, and the movement of the diaphragm away from the second orifice gradually closes the second orifice, thereby reducing the flow rate through the second orifice. Typically, the second orifice is not completely closed (i.e., closed) during printing.

[0027] Preferably, the pressure in the regulating chamber is reduced, causing the diaphragm to move toward the second orifice.

[0028] Preferably, the outer surface of the second valve component opens away from the diaphragm.

[0029] Preferably, the outer surface of the second valve component opens non-linearly.

[0030] Preferably, the linear movement of the second valve component causes a linear change in the closed area of ​​the second orifice, such that the flow rate through the second orifice is linearly proportional to the distance the second valve component moves.

[0031] In a related aspect, an inkjet printer is provided, the inkjet printer comprising:

[0032] The pressure regulating valve described above;

[0033] Ink cartridge, which is connected to the inlet port; and

[0034] An inkjet printhead that is connected to an output port.

[0035] Preferably, the ink tank is positioned at a certain height above the pressure regulating valve to supply ink to the inlet port under positive pressure under gravity.

[0036] Preferably, the inkjet printhead draws out ink under negative pressure at the exit port during printing.

[0037] Preferably, the vacuum source connected to the inkjet printhead draws out negative pressure at the exit port during at least some non-printing periods.

[0038] Preferably, during use, the pressure regulating valve maintains the negative pressure of the ink at the printhead within a predetermined pressure range.

[0039] Preferably, the ink level in the ink tank is at a height above the orifice. h 1 The orifice is positioned at a height relative to the print head. h 2 Furthermore, the back pressure of the ink supplied to the printhead is controlled by the following: h 1 , h 2 The position of the valve component relative to the orifice, and the pump speed of the pump connected to the printhead outlet port.

[0040] In a second aspect, an ink delivery system is provided for supplying ink to an inkjet printhead at a predetermined back pressure, the ink delivery system comprising:

[0041] A pressure regulating valve having a valve outlet connected to the printhead inlet port and a passive control valve component for controlling the ink flow rate through the orifice;

[0042] An ink reservoir connected to the valve inlet of a pressure regulating valve, positioned above the pressure regulating valve and printhead, the ink reservoir having an air vent to the atmosphere for supplying ink to the pressure regulating valve under gravity; and

[0043] The pump is connected to the printhead outlet port.

[0044] in:

[0045] The ink level in the ink can is at a height above the orifice. h 1 Place;

[0046] The orifice is positioned at a height relative to the print head. h 2 Furthermore, the back pressure of the ink supplied to the printhead is controlled by the following: h 1 , h 2 The position of the valve component relative to the orifice, and the pump speed.

[0047] Preferably, the pump is connected to the ink tank via an ink return line.

[0048] Preferably, the pressure regulating valve includes:

[0049] A regulating chamber having a diaphragm operatively connected to a valve member, such that movement of the diaphragm causes movement of the valve member relative to an orifice; and

[0050] A biasing mechanism for elastically biasing the diaphragm away from the orifice.

[0051] Preferably, the pressure regulating valve is as described above in conjunction with the first aspect and its preferred embodiments.

[0052] Preferably, height h 1 Controlled by one or more ink level sensors in conjunction with a refill pump that receives ink from a bulk ink reservoir.

[0053] Preferably, the pressure regulating valve is positioned above the printhead. Alternatively, the pressure regulating valve is positioned below the printhead or at the same height as the printhead.

[0054] In a third aspect, a pressure regulating valve for an inkjet printhead is provided, the valve comprising:

[0055] Valve inlet;

[0056] Valve outlet;

[0057] Fluid flow path, which is defined between the valve inlet and the valve outlet;

[0058] The orifice is located in the flow path;

[0059] A movable valve component configured to regulate the fluid flow rate through an orifice;

[0060] A regulating chamber having a valve outlet and including a diaphragm operatively connected to a valve member such that movement of the diaphragm causes movement of the valve member relative to an orifice; and

[0061] A biasing mechanism for elastically biasing a diaphragm away from an orifice, wherein the outer surface of the valve member opens non-linearly away from the diaphragm.

[0062] Preferably, the linear movement of the valve member relative to the orifice causes a linear change in the closed area of ​​the orifice, such that the flow rate through the orifice is linearly proportional to the distance the valve member moves.

[0063] Preferably, the biasing mechanism includes a spring operatively connected to the diaphragm, wherein the spring biases the valve member toward the closing orifice.

[0064] Preferably, during use, the diaphragm and spring work together to passively control the flow rate through the orifice.

[0065] Preferably, the valve component and the orifice have rigid mating surfaces.

[0066] Preferably, the movement of the diaphragm toward the orifice gradually opens the orifice, thereby increasing the flow rate through the orifice, and the movement of the diaphragm away from the orifice gradually closes the orifice, thereby reducing the flow rate through the orifice.

[0067] Preferably, the pressure in the regulating chamber is reduced to move the diaphragm toward the orifice.

[0068] In a related aspect, an inkjet printing system is provided, which includes a pressure regulating valve as described above in conjunction with the first aspect.

[0069] As used herein, the term "ink" is considered to refer to any printing fluid that can be printed from an inkjet printhead. Ink may or may not contain colorants. Accordingly, the term "ink" can include conventional dye-based or pigment-based inks, infrared inks, fixatives (such as pre-coatings and finishing agents), 3D printing fluids (such as binder fluids), functional fluids (such as solar inks, sensing inks, etc.), and so on. In the context of reference to fluids or printing fluids, this is not intended to limit the meaning of "ink" as used herein. Attached Figure Description

[0070] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0071] Figure 1 An ink delivery system with a single printhead is shown;

[0072] Figure 2 An ink delivery system with two printheads is shown;

[0073] Figure 3 It is a 3D view of a pressure regulating valve;

[0074] Figure 4 It is a three-dimensional cross-sectional view of a pressure regulating valve; and

[0075] Figure 5 This is a side view of a valve component used to regulate the flow rate through an orifice. Detailed Implementation

[0076] Ink delivery system

[0077] refer to Figure 1 The diagram schematically illustrates an ink delivery system 1 for an inkjet printing system having a printing module 2 including an inkjet printhead 4. The printhead 4 is typically a user-replaceable page-width (or “line header”) printhead of the type described, for example, in US2011 / 0279566, US 9,950,527, or US 10,717,282, the contents of which are incorporated herein by reference.

[0078] Ink is fed to printhead 4 via intermediate ink reservoir 6, which has a supply port 7 connected to printhead inlet port 8 via ink supply line 12. Intermediate ink reservoir 6 has a vent 14 to the atmosphere and feeds ink into ink supply line 12 under gravity. Intermediate ink reservoir 6 can be configured to handle degassed ink, as described in US10,639,903, the contents of which are incorporated herein by reference.

[0079] The return port 13 of the intermediate ink tank 6 is connected to the printhead outlet port 16 via the ink return line 18. Therefore, the intermediate ink tank 6, the ink supply line 12, the printhead 4, and the ink return line 18 together form a closed fluid loop. Typically, the ink supply line 12 and the ink return line 18 are made of flexible tubing of a certain length.

[0080] The ink return line 18 has a circulation pump 20 (e.g., a diaphragm pump) located downstream of the printhead 4 for circulating ink around a closed fluid loop.

[0081] The closed fluid loop further includes: a deaerator 22 located downstream of pump 20 in ink return line 18 for degassing ink; a filter 23 located downstream of intermediate ink tank 6 in ink supply line 12 for filtering ink supplied to printhead 4; and a compliance device 25 located in ink return line between printhead outlet port 16 and circulation pump 20 for suppressing ink pressure fluctuations. Filter 23 may be of the type described, for example, in US 10,369,802, the contents of which are incorporated herein by reference. Alternatively, filter 23 may be integrated into intermediate ink tank 6 as described in U.S. Provisional Application No. 62 / 990,911, filed March 17, 2020, the contents of which are incorporated herein by reference.

[0082] Ink delivery system 1 is designed to deliver ink as... Figure 1 The ink supply line 12 and the ink return line 18, as shown, circulate in a clockwise direction around a closed fluid loop. In this way, the ink can be continuously degassed and filtered to maintain optimal print quality by minimizing air bubbles and particles entering the printhead 4.

[0083] Ink consumed by printhead 4 during normal printing or maintenance operations is replenished from bulk ink reservoir 24, which feeds ink into return line 18 via ink refill line 26 equipped with refill pump 28. Actuation of refill pump 28 is controlled by feedback from "high" ink level sensor 27A and "low" ink level sensor 27B of intermediate ink tank 6. When ink in intermediate ink tank 6 is sensed to be at a predetermined "high" level, refill pump 28 is deactivated; and when ink in intermediate ink tank 6 is sensed to be at a predetermined "low" level, refill pump is activated to replenish ink in the closed fluid loop from bulk ink reservoir 24.

[0084] For purging, isolating, and / or replacing printhead 4, print module 2 includes a printhead shut-off valve 30 located on the outlet side of printhead 4 and an air inlet line 32 controlled by an air shut-off valve 34 located on the inlet side. An upstream pressure regulating valve 50 (described in detail below) is positioned in the ink supply line 12 between the intermediate ink tank 6 and print module 2; this upstream pressure regulating valve also functions as an ink shut-off valve. Therefore, when printhead 4 needs to be purged (e.g., for printhead replacement), pressure regulating valve 50 is closed, while air shut-off valve 34 is opened. Circulation pump 20 is actuated, drawing air through printhead 4, thereby removing ink from the internal ink supply passages. After ink has been removed from printhead 4, outlet shut-off valve 30 is closed, thereby isolating the printhead and allowing for clean removal and replacement. Typically, printhead 4 is also isolated via shut-off pressure regulating valve 50 and outlet shut-off valve 30 when the printing system is not in use.

[0085] For printhead filling operations, a vacuum cap (not shown) may be used in conjunction with a circulation pump 20 to draw ink through the ink supply channels of the printhead and into the nozzles, as described in U.S. Application No. 17 / 174,090, filed February 11, 2021, the contents of which are incorporated herein by reference.

[0086] Pressure regulation

[0087] As those skilled in the art will understand, for optimal operation, it is important that the printhead 4 receives ink under a predetermined back pressure. If the ink pressure is too negative, the ink confined inside the inkjet nozzles may be drawn back into the printhead channel, thereby emptying the printhead; if the ink pressure is too positive, the ink may overflow from the inkjet nozzles onto the nozzle plate of the printhead.

[0088] Gravity-feed ink delivery systems (such as those described in US 10,639,903) offer the advantage of passively controlling back pressure. However, positioning the intermediate ink tank below the printhead is generally inconvenient. In most inkjet printing systems, this space is occupied by maintenance systems, media feeding systems, etc. Furthermore, intermediate ink tanks that feed ink to multiple printheads cannot achieve accurate local pressure control for each printhead.

[0089] Active pressure control systems (such as the active pressure control system described in US 10,252,540) offer the advantage of accurate local pressure control without design limitations on the positioning of system components. However, such systems require expensive pumps and sensing circuitry, which may be economically infeasible for smaller inkjet printing systems.

[0090] Figure 1The ink delivery system 1 shown implements localized passive adjustment of the back pressure in the printhead 4, while employing an intermediate ink tank 6 positioned above the printhead. The back pressure experienced by the printhead 4 is controlled by a combination of the following factors: the height of the intermediate ink tank 6 relative to the pressure regulating valve 50. h 1 The passively controlled flow rate through the orifice in the pressure regulating valve 50, and the height of the pressure regulating valve relative to the print head 4. h 2 And the pumping speed of downstream pump 20. Pressure regulating valve 50 is a key component of the system and has the following dual functions: passive pressure regulation via the relative closure of the orifice; and ink shut-off valve for isolating printhead 4, purging operations, etc.

[0091] Furthermore, since the pressure regulating valve 50 is designed as a compact and inexpensive component of the ink delivery system 1, it can be placed close to the printhead 4, and in some embodiments, it can be included in the printing module 2, which itself is a replaceable module containing a replaceable printhead 4. (See reference...) Figure 2 The ink delivery system, comprising two printheads 4 connected in parallel, has a corresponding pressure regulating valve 50 for each printhead, thereby providing local pressure control for each printhead from a shared intermediate ink tank 6. In this way, if one printhead 4 has a higher ink demand than the other, the operation of the corresponding pressure regulating valve 50 can be used to keep both printheads at relatively equal ink pressures.

[0092] Now refer to Figure 3 and Figure 4 A pressure regulating valve 50 is described in detail. The pressure regulating valve 50 includes a valve inlet 52, a valve outlet 54, and a fluid flow path defined between the valve inlet and the valve outlet. A first orifice 56 is located downstream of the valve inlet 52 in the flow path. The first orifice 56 has a first seat 58 that is sealable by means of a movable first valve member 60 having a compliant plug 62 configured for sealing engagement with the first seat. Figure 4 As shown, the first valve member 60 is shown in the closed position, whereby the compliant plug seals against the first seat 58. The first valve member 60 is located away from the first seat (e.g., Figure 4The downward movement of the first valve member 60 (as shown) disengages the valve member from the first seat and opens the first orifice, allowing fluid to flow through the first orifice under positive pressure from the valve inlet 52. The movement of the first valve member 60 between the open and closed positions is controlled by an actuator in the form of a solenoid 66. When the solenoid 66 is actuated, the first valve member 60 moves away from the first seat 58 to open the first orifice 56; and when the solenoid 66 is retracted, the first valve member 60 seals against the first seat 58 to close the first orifice 56. The solenoid 66 operates under the control of a separate controller (not shown) operatively connected to an electrical terminal 68. Thus, the first orifice and the first valve member, under the control of the solenoid 66, function as a shut-off valve in the ink supply line 12.

[0093] A second orifice 70 is positioned downstream of the first orifice 56 in the flow path, and the first and second orifices are connected via an intermediate flow channel 72. The second orifice 70 is defined in the base of a regulating chamber 74, which forms the upper portion of the pressure regulating valve 50. The regulating chamber 74 includes a valve outlet 54 located in its sidewalls and a diaphragm 76 located in its top. The diaphragm 76 is operatively connected to a second valve member 78, which is slidably movable relative to the second orifice 70 to gradually close or gradually open the second orifice. The second valve member 78 is biased away from the second orifice 70 by means of a spring 80, one end of which is connected to the diaphragm 76 (and the second valve member 78), and the opposite end is connected to a fixed support 82. Figure 3 and Figure 4 In the illustrated embodiment, the fixed support 82 is an external structure; however, it should be understood that the fixed support 82, to which one end of the spring 80 is attached, can be integrated into the top of the adjustment chamber 74, wherein the spring extends through the inner top cavity (not shown).

[0094] As the second valve member 78 opens away from the diaphragm 76, the second valve member faces the second orifice 70 (i.e., as shown in the image). Figure 4 The downward movement (as shown) causes the second orifice to gradually open, and the second valve component moves away from the second orifice (i.e., as shown downward). Figure 4 The upward movement (as shown) gradually closes the second opening. Figure 4 As shown, the second orifice 70 is depicted in the closed position, with the diaphragm 76 not flexed. However, the second orifice 70 and the second valve member 78 do not function as a shut-off pressure regulating valve 50, but are only used to regulate the fluid flow rate through the second orifice. Therefore, the second valve member 78 and the second orifice 70 have rigid mating surfaces without a sealing function. Typically, the second valve member 78 and the second orifice 70 are formed of metal and / or rigid plastic.

[0095] During printing, the first orifice 56 is opened by the actuation of the solenoid 66, and the flow rate through the pressure regulating valve 50 is passively controlled by the position of the second valve member 78 relative to the second orifice 70. When ink demand is high, the printhead 4 draws a relatively large negative pressure at the valve outlet 54, thereby reducing the fluid pressure in the regulating chamber 74. This reduced fluid pressure tends to cause the diaphragm 76 to flex towards the second orifice 70 against the bias of the spring 80, thereby increasing the fluid flow rate through the second orifice. Conversely, when the fluid pressure in the regulating chamber 74 increases, the diaphragm flexes away from the second orifice 70, thereby reducing the fluid flow rate through the second orifice. Therefore, the ink pressure experienced at the printhead 4 is determined at least in part by the balance of forces between the flexing diaphragm 76 and the spring 80.

[0096] Advantageously, since the second valve component 78 that controls the ink pressure at printhead 4 does not have a shut-off function, the hysteresis problem caused by the opening and closing of the valve and the valve jamming problem are minimized.

[0097] exist Figure 5 In the preferred embodiment shown, the outer surface of the second valve member 78 opens non-linearly. For example, the second valve member 78 may be generally bell-shaped or flared, whereby its curved outer surface determines the degree of closure of the second orifice 70. In this way, linear movement of the second valve member 78 relative to the second orifice 70 causes a linear change in the unclosed area of ​​the second orifice. The unclosed area of ​​the second orifice 70 is proportional to the flow rate through the second orifice, such that the flow rate is linearly proportional to the distance the, for example, flared second valve member 78, moves.

[0098] Of course, it should be understood that the invention has been described by way of example only, and modifications to the details are possible within the scope of the invention as defined in the appended claims.

Claims

1. A pressure regulating valve for an inkjet printhead, the valve comprising: Valve inlet; Valve outlet; A fluid flow path, the fluid flow path being defined between the valve inlet and the valve outlet; A first orifice, the first orifice being positioned in the flow path, the first orifice having a sealable first seat; A movable first valve member, the movable first valve member being configured for sealing engagement with the first seat; A second orifice is located in the flow path; A movable second valve component, the movable second valve component being configured to regulate the fluid flow rate through the second orifice; A regulating chamber having the valve outlet and including a diaphragm operatively connected to the movable second valve member, such that movement of the diaphragm causes the movable second valve member to move relative to the second orifice; as well as A biasing mechanism for elastically biasing the diaphragm away from the second orifice. in: The movable second valve member is bell-shaped or horn-shaped, and the curved outer surface of the movable second valve member determines the degree of closure of the second orifice; and In use, the movement of the diaphragm toward the second orifice gradually opens the second orifice, thereby increasing the flow rate through the second orifice, and the movement of the diaphragm away from the second orifice gradually closes the second orifice, thereby reducing the flow rate through the second orifice.

2. The pressure regulating valve as described in claim 1, wherein, The second orifice is located downstream of the first orifice.

3. The pressure regulating valve as described in claim 1, wherein, The movable first valve component includes a compliant plug for sealing engagement with the first seat.

4. The pressure regulating valve as described in claim 1, wherein, The movable first valve component is operatively connected to the actuator for opening and sealingly closing the first orifice.

5. The pressure regulating valve as described in claim 1, wherein, The biasing mechanism includes a spring operatively connected to the diaphragm, wherein the spring biases the movable second valve member toward closing the second orifice.

6. The pressure regulating valve as described in claim 5, wherein, In use, the diaphragm and the spring work together to passively control the flow rate through the second orifice.

7. The pressure regulating valve as described in claim 1, wherein, The movable second valve component and the second orifice have rigid engagement surfaces.

8. The pressure regulating valve as described in claim 1, wherein, The pressure reduction in the regulating chamber causes the diaphragm to move toward the second orifice.

9. The pressure regulating valve as claimed in claim 1, wherein, The outer surface of the movable second valve component opens non-linearly.

10. The pressure regulating valve as claimed in claim 9, wherein, The linear movement of the movable second valve component relative to the second orifice causes a linear change in the closed area of ​​the second orifice, such that the flow rate through the second orifice is linearly proportional to the distance the movable second valve component moves.

11. An inkjet printing system, comprising: The pressure regulating valve according to claim 1; Ink reservoir, the ink reservoir being connected to the valve inlet; An inkjet printhead having a printhead inlet port connected to the valve outlet.

12. The inkjet printing system of claim 11, wherein, The ink tank is positioned at a certain height above the pressure regulating valve to supply ink to the valve inlet under positive pressure under gravity.

13. The inkjet printing system of claim 11, wherein, During printing, the inkjet printhead draws out negative pressure of ink at the valve outlet.

14. The inkjet printing system of claim 11, wherein, A pump or vacuum source connected to the inkjet printhead draws negative pressure at the valve outlet during at least some non-printing periods.

15. The inkjet printing system of claim 11, wherein, During use, the pressure regulating valve maintains the negative pressure of the ink at the printhead within a predetermined pressure range.

Images