Patent Publication Number: US-9895897-B2

Title: Selectively provide pressure differences between reservoirs to cause printing fluid movement

Description:
BACKGROUND 
     A printing apparatus may include a reservoir and a printing fluid applicator. The reservoir may supply printing fluid to the printing fluid applicator. The printing fluid applicator may apply the printing fluid to form images on a substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting examples are described in the following description, read with reference to the figures attached hereto and do not limit the scope of the claims. Dimensions of components and features illustrated in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily to scale. Referring to the attached figures: 
         FIG. 1  is a block diagram illustrating a printing apparatus according to an example. 
         FIGS. 2A-2C  are schematic views illustrating a printing apparatus according to examples. 
         FIG. 3  is a block diagram illustrating a printing system according to an example. 
         FIG. 4  is a block diagram illustrating the printing system of  FIG. 3  according to an example. 
         FIG. 5  is a flowchart illustrating a method of moving printing fluid within a printing apparatus according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     A printing apparatus may include a reservoir and a printing fluid applicator. The reservoir may supply printing fluid to the printing fluid applicator. The printing fluid applicator may apply the printing fluid therein to form images on a substrate. Printing fluid such as ultraviolet curing ink, however, may need to possess acceptable properties to be successfully applied by the printing fluid applicator to the substrate. At times, however, such acceptable properties may not be attained when a temperature of the printing fluid falls below an acceptable temperature, for example, due to it being idle for an un desired amount of time. Consequently, the printing fluid may possess unsatisfactory properties and may not be satisfactorily applied to the substrate. 
     In examples, a printing apparatus includes a first reservoir, a second reservoir, an applicator receiving area, and a differential pressure system. The applicator receiving area may receive a printing fluid applicator placed in fluid communication with the first reservoir and the second reservoir. The differential pressure system may selectively provide a first pressure difference between the first reservoir and the second reservoir to cause printing fluid to move from the first reservoir, and through the printing fluid applicator to the second reservoir. The differential pressure system may include a switching manifold, and the differential pressure system may selectively provide a second pressure difference between the first reservoir and the second reservoir to cause the printing fluid to move from the second reservoir, and through the printing fluid applicator to the first reservoir. 
     For example, printing fluid in the printing fluid applicator may be directed to flow in a first direction in response to the first pressure difference and flow in a reverse direction (e.g., second direction) in response to the second pressure difference. The reversing of the direction of fluid flow of the printing fluid within the printing fluid applicator may be repeated. The switching manifold may direct at least one of a first amount of pressure and a second amount of pressure to each one of the first reservoir and the second reservoir to selectively establish one of the first pressure difference and the second pressure difference between the first reservoir and the second reservoir. Consequently, the application and changing of pressure differences between respective reservoirs moves printing fluid to assist in maintaining a target temperature and acceptable properties of the printing fluid within the printing fluid applicator. Consequently, the printing fluid may possess acceptable properties to be satisfactory applied by the printing fluid applicator to a substrate. 
       FIG. 1  is a block diagram illustrating a printing apparatus according to an example. Referring to  FIG. 1 , in some examples, a printing apparatus  100  may include a first reservoir  10 , a second reservoir  11  an applicator receiving area  12 , and a differential pressure system  13 . The first reservoir  11 ) and the second reservoir  11  may provide printing fluid to the printing fluid applicator. The applicator receiving area  12  may receive a printing fluid applicator to be placed in fluid communication with the first reservoir  10  and the second reservoir  11 . In some examples, the printing fluid applicator may be removably disposed in the applicator receiving area  12 . Alternatively, the printing fluid applicator may be permanently disposed in the applicator receiving area  12 . 
     Referring to  FIG. 1 , in some examples, the differential pressure system  13  may include a switching manifold  29 . The differential pressure system  13  may selectively provide a first pressure difference between the first reservoir  10  and the second reservoir  11  to cause printing fluid to move from the first reservoir  10 , and through the printing fluid applicator to the second reservoir  11 . Additionally, the differential pressure system  13  may selectively provide a second pressure difference between the first reservoir  10  and the second reservoir  11  to cause the printing fluid to move from the second reservoir  11 , and through the printing fluid applicator to the first reservoir  10 . Accordingly, within the printing fluid applicator, printing fluid may move in a first direction from one end of the printing fluid applicator to another end of the printing fluid applicator in response to the first pressure difference. 
     Further, within the printing fluid applicator, printing fluid may move in a second direction from the other end to the one end in response to the second pressure difference. For example, the second direction may be opposite to the first direction. The switching manifold  29  may direct at least one of a first amount of pressure and a second amount of pressure to each one of the first reservoir  10  and the second reservoir  11  to selectively establish one of the first pressure difference and the second pressure difference between the first reservoir  10  and the second reservoir  11 . 
     In some examples, the differential pressure system  13  may be implemented in hardware, software including firmware, or combinations thereof. The firmware, for example, may be stored in memory and executed by a suitable instruction-execution system. If implemented in hardware, as in an alternative example, the differential pressure system  13  may be implemented with any or a combination of technologies which are well known in the art (for example, discrete-logic circuits, application-specific integrated circuits (ASICs), programmable-gate arrays (PGAs), field-programmable gate arrays (FPGAs)), and/or other later developed technologies. In other examples, the differential pressure system  13  may be implemented in a combination of software and data executed and stored under the control of a computing device. 
       FIGS. 2A-2C  are schematic views illustrating a printing apparatus according to examples. Referring to  FIGS. 2A-2C , in some examples, the printing apparatus  200  may include the first reservoir  10 , the second reservoir  11 , the applicator receiving area  12 , and the differential pressure system  13  previously discussed with respect to the printing apparatus  100  of  FIG. 1 . Referring to  FIG. 2 , in some examples, the differential pressure system  13  may also include an air movement device  25  and a control device  26 . The air movement device  25  may provide a first amount of pressure and a second amount of pressure. In some examples, the air movement device  25  may include a pressure supply  27 , and a pressure adjustment module  28 . The pressure supply  27  may supply the first amount of pressure. The pressure adjustment module  28  may also communicate with the pressure supply  27  to supply the second amount of pressure. In some examples, the first amount of pressure and the second amount of pressure may be respective vacuum pressures. In some examples, the printing apparatus  200  may include at least one fluid parameter sensor (not illustrated) in communication with printing fluid to determine at least one of respective pressures and temperatures of the printing fluid and communicate such information to the control device  26 . 
     Referring to  FIGS. 2A-2C , in some examples, the control device  26  may selectively establish the first pressure difference and the second pressure difference between the first reservoir  10  and the second reservoir  11  at a predetermined interval. The predetermined interval may correspond to a period of time between the establishment of the first pressure difference and the second pressure difference. In some examples, the period of time may be about forty seconds. The control device  26  may control whether the first reservoir  10  and the second reservoir  11  receive the first amount of pressure and the second amount of pressure. In some examples, the control device  26  may include a switching module  29  including a first switch  29   a , a second switch  29   b , and a control module  29   c.    
     Referring to  FIGS. 2A-2C , in some examples, the switching manifold  29  may establish communication paths between the pressure supply  27  and the pressure adjustment module  28  with the first reservoir  10  and the second reservoir  11 , respectively. For example, the first switch  29   a  may direct at least one of the first amount of pressure and the second amount of pressure to the first reservoir  10 . For example, the second switch  29   b  may direct at least one of the first amount of pressure and the second amount of pressure to the second reservoir  11 . The control module  29   c  may control the first switch  29   a  and the second switch  29   b  to selectively direct at least one of the first amount of pressure and the second amount of pressure to the first reservoir  10  and the second reservoir  11  and the respective timing thereof. Accordingly, the switching manifold  29  may selectively establish one of the first pressure difference and the second pressure difference between the first reservoir  10  and the second reservoir  11  at the predetermined interval. In some examples, the first pressure difference may be about eighty pascal (Pa). Accordingly, within the printing fluid applicator  24 , printing fluid may move in a first direction f 1  from one end to another end in response to the first pressure difference. Further, within the printing fluid applicator  24 , printing fluid may move in a second direction f 2  from the other end to the one end in response to the second pressure difference. 
     Referring to  FIGS. 2A-2C , in some examples, the printing apparatus  200  may also include the printing fluid applicator  24  disposed in the applicator receiving area  12 , and in fluid communication with the first reservoir  10  and the second reservoir  11 . In some examples, the printing fluid applicator  24  may include a printhead, a plurality of printhead modules, a print bar, and/or a printhead assembly, and the like. For example, the printing fluid applicator  24  may include an inkjet printhead to eject printing fluid such as ultraviolet curing ink to form images on the substrate. The printing apparatus  200  may also include a first conduit  23   a , a second conduit  23   b , and at least one heating unit  20   a  and  21   a , a replaceable printing fluid supply  22   a , and a printing fluid pump  22   b.    
     The first conduit  23   a  may place the first reservoir  10  in fluid communication with the printing fluid applicator  24  to move the printing fluid there between. The second conduit  23   b  may place the second reservoir  11  in fluid communication with the printing fluid applicator  24  to move the printing fluid there between. In some examples, in response to the first pressure difference, printing fluid flows in a first direction f 1  from the first reservoir  10 , through the first conduit  23   a , through the printing fluid applicator  24 , through the second conduit  23   b , and to the second reservoir  11  as illustrated in  FIG. 2B . Alternatively, in response to the second pressure difference, printing fluid flows in a second direction f 2  from the second reservoir  11 , through the second conduit  23   b , through the printing fluid applicator  24 , through the first conduit  23   a , and to the first reservoir  10  as illustrated in  FIG. 2C . For example, the second direction f 2  may be reversed from the first direction f 1 . 
     The at least one heating unit  20   a  and  21   a  may heat the printing fluid in at least one of the first reservoir  10 , the second reservoir  11 , the first conduit  23   a , and the second conduit  23   b . At least one heating unit  20   a  and  21   a  may include a first heater  20   a  disposed in the first reservoir  10  and a second heater  21   a  disposed in the second reservoir  11 . The first and second heater  20   a  and  21   a  may heat printing fluid to a target temperature to maintain the printing fluid in the printing fluid applicator  24  within a target temperature range. In some examples, the target temperature may be about fifty degrees Celsius and the target temperature range may be forty-nine to fifty-one degrees Celsius. The replaceable printing fluid supply  22   a  may supply the printing fluid. The printing fluid pump  22   b  may pump the printing fluid from the replaceable printing fluid supply  22   a  to at least one of the first reservoir  10  and the second reservoir  11 . 
       FIG. 3  is a block diagram illustrating a printing system according to an example. Referring to  FIG. 3 , in some examples, a printing system  300  may include a first set of reservoirs  31  including a first reservoir  10  and a second reservoir  11 , a second set of reservoirs  32  including a third reservoir  36  and a fourth reservoir  37 , a first printhead module  34   a , a second printhead module  34   b , and a differential pressure system  33 . The first printhead module  34   a  may be disposed between and in fluid communication with the first reservoir  10  and the second reservoir  11 . The second printhead module  34   b  may be disposed between and in fluid communication with the third reservoir  36  and the fourth reservoir  37 . 
     Referring to  FIG. 3 , in some examples, the differential pressure system  33  may selectively provide a first pressure difference between the first reservoir  10  and the second reservoir  11  to cause a first printing fluid to move from the first reservoir  10 , and through the first printhead module  34   a  to the second reservoir  11 . The differential pressure system  33  may also selectively provide a second pressure difference between the first reservoir  10  and the second reservoir  11  to cause the printing fluid to move from the second reservoir  11 , and through the first printhead module  34   a  to the first reservoir  10 . The differential pressure system  33  may also selectively provide the first pressure difference between the third reservoir  36  and the fourth reservoir  37  to cause a second printing fluid to move from the third reservoir  36 , and through the second printhead module  34   b  to the fourth reservoir  37 . The differential pressure system  33  may also selectively provide the second pressure difference between the third reservoir  36  and the fourth reservoir  37  to cause the second printing fluid to move from the fourth reservoir  37 , and through the second printhead module  34   b  to the third reservoir  36 . 
       FIG. 4  is a block diagram illustrating the printing system of  FIG. 3  according to an example. Referring to  FIG. 4 , in some examples, the differential pressure system  33  may include the air movement device  25  and the control device  25  as previously discussed with respect to the printing apparatus  200  of  FIG. 2 . Referring to  FIG. 4 , in some examples, the air movement device  26  may provide a first amount of pressure and a second amount of pressure. In some examples, the air movement device  25  may include the pressure supply  27  and the pressure adjustment module  28 . The pressure supply  27  may supply the first amount of pressure. The pressure adjustment module  28  may communicate with the pressure supply  27  to supply the second amount of pressure. 
     Referring to  FIG. 4 , in some examples, the control device  26  may selectively establish the first pressure difference end the second pressure difference between the first reservoir  10  and the second reservoir  11  at a predetermined interval. The predetermined interval may correspond to a period of time between the establishment of the first pressure difference and the second pressure difference. The control device  26  may control whether the first reservoir  10  and the second reservoir  11  receive the first amount of pressure and the second amount of pressure. In some examples, the control device  25  may include a switching module  29  including a first switch  29   a , a second switch  29   b , a third switch  29   d , a fourth switch  29   e , and a control module  29   c . In some examples, the printing system  300  may include at least one fluid parameter sensor (not illustrated) in communication with printing fluid to determine at least one of respective pressures and temperatures of the printing fluid and communicate such information to the control device  26 . 
     Referring to  FIG. 4 , in some examples, the switching manifold  29  may establish communication paths between the pressure supply  27  and the pressure adjustment module  28  with the first reservoir  10 , the second reservoir  11 , the third reservoir  36 , and the fourth reservoir  37 , respectively. For example, the first switch  29   a  may direct at least one of the first amount of pressure and the second amount of pressure to the first reservoir  10 . The second switch  29   b  may direct at least one of the first amount of pressure and the second amount of pressure to the second reservoir  11 . The third switch  29   d  may direct at least one of the first amount of pressure and the second amount of pressure to the third reservoir  36 . Additionally, the fourth switch  29   e  may direct at least one of the first amount of pressure and the second amount of pressure to the fourth reservoir  37 . 
     The control module  29   c  may control the first switch  29   a  and the second switch  29   b  to selectively direct at least one of the first amount of pressure and the second amount of pressure to the first reservoir  10  and the second reservoir  11 , respectively, and the respective timing thereof. The control module  29   c  may also control the third switch  29   d  and the fourth switch  29   e  to selectively direct at least one of the first amount of pressure and the second amount of pressure to the third reservoir  36  and the fourth reservoir  37 , respectively, and the respective timing thereof. Accordingly, the switching manifold  29  may also selectively establish one of the first pressure difference and the second pressure difference between the first reservoir  10  and the second reservoir  11  at a predetermined interval. Additionally, the switching manifold  29  may also selectively establish one of the first pressure difference and the second pressure difference between the third reservoir  10  and the fourth reservoir  11  at the predetermined interval. 
     Referring to  FIG. 4 , in some examples, the control device  26  may selectively establish the first pressure difference and the second pressure difference between the first reservoir  10  and the second reservoir  11  at a first predetermined interval, for example, by controlling whether the first reservoir  10  and the second reservoir  11  receive the first amount of pressure and the second amount of pressure. The control device  26  may also selectively establish the first pressure difference and the second pressure difference between the third reservoir  36  and the fourth reservoir  37  at a second predetermined interval, for example, by controlling whether the third reservoir  36  and the fourth reservoir  37  receive the first amount of pressure and the second amount of pressure. A heater may be disposed in each one of the first, second, third and fourth reservoir  10 ,  11 ,  36 , and  37  to heat printing fluid to a target temperature. 
       FIG. 5  is a flowchart illustrating a method of moving printing fluid within a printing apparatus according to an example. In block S 510 , a first reservoir is placed in fluid communication with a printing fluid applicator of the printing apparatus by a first conduit to move the printing fluid there between. In block S 512 , a second reservoir is placed in fluid communication with the printing fluid applicator by a second conduit to move the printing fluid there between. In block S 514 , a first pressure difference between the first reservoir and the second reservoir is selectively provided by a differential pressure system to cause the printing fluid to move from the first reservoir through the printing fluid applicator to the second reservoir. For example, a first amount of pressure and a second amount of pressure may be provided by an air movement device of the differential pressure system. Additionally, whether the first reservoir and the second reservoir receive the first amount of pressure and the second amount of pressure are controlled by a control device of the differential pressure system. In block S 516 , a second pressure difference between the first reservoir and the second reservoir is selectively provided by the differential pressure system to cause the printing fluid to move from the second reservoir through the printing fluid applicator to the first reservoir. 
     In block S 518 , the printing fluid in at least one of the first reservoir, the second reservoir, the first conduit and the second conduit is heated by at least one heating unit. For example, the at least one heating unit may include a first heater disposed at the first reservoir and a second heater disposed at the second reservoir to maintain the printing fluid in the fluid applicator within a predetermined temperature range. In some examples, the method may also include establishing a predetermined interval by the control device to switch between the selectively providing the first pressure difference and the selectively providing the second pressure difference. Additionally, the method may also include selectively establishing the first pressure difference and the second pressure difference between the first reservoir and the second reservoir at the predetermined interval by the control device. 
     In some examples, providing the first amount of pressure and the second amount of pressure by the air movement may include supplying the first amount of pressure by a pressure supply of the air movement device and communicating with the pressure supply by a pressure adjustment module of the air movement device to supply the second amount of pressure. In some examples, controlling whether the first reservoir and the second reservoir receive the first amount of pressure and the second amount of pressure by the control device may also include establishing communication paths between each one of the pressure supply and the pressure adjustment module with the first reservoir and the second reservoir by a switching manifold of the air movement device, respectively. 
     Additionally, controlling whether the first reservoir and the second reservoir receive the first amount of pressure and the second amount of pressure by the control device may also include communicating with the switching manifold to direct at least one of the first amount of pressure and the second amount of pressure to each one of the first reservoir and the second reservoir by the control device to selectively establish one of the first pressure difference and the second pressure difference between the first reservoir and the second reservoir at a predetermined interval. 
     It is to be understood that the flowchart of  FIG. 5  illustrates architecture, functionality, and/or operation of examples of the present disclosure. If embodied in software, each block may represent a module, segment, or portion of code that includes one or more executable instructions to implement the specified logical function(s). If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). Although the flowchart of  FIG. 5  illustrates a specific order of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be rearranged relative to the order illustrated. Also, two or more blocks illustrated in succession in  FIG. 5  may be executed concurrently or with partial concurrence. All such variations are within the scope of the present disclosure. 
     The present disclosure has been described using non-limiting detailed descriptions of examples thereof that are not intended to limit the scope of the general inventive concept. It should be understood that features and/or operations described with respect to one example may be used with other examples and that not all examples have all of the features and/or operations illustrated in a particular figure or described with respect to one of the examples. Variations of examples described will occur to persons of the art. Furthermore, the terms “comprise,” “include,” “have” and their conjugates, shall mean, when used in the disclosure and/or claims, “including but not necessarily limited to.” 
     It is noted that some of the above described examples may include structure, acts or details of structures and acts that may not be essential to the general inventive concept and which are described for illustrative purposes. Structure and acts described herein are replaceable by equivalents, which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the general inventive concept is limited only by the elements and limitations as used in the claims.