Patent Publication Number: US-11654678-B2

Title: Nozzle characteristics

Description:
BACKGROUND 
     Fluid ejection dies may eject fluid drops via nozzles thereof. Nozzles may include fluid ejectors that may be actuated to thereby cause ejection of drops of fluid through nozzle orifices of the nozzles. Some example fluid ejection dies may be printheads, where the fluid ejected may correspond to ink. 
    
    
     
       DRAWINGS 
         FIG.  1    is a block diagram that illustrates some components of an example fluid ejection device. 
         FIG.  2    is a block diagram that illustrates some components of an example fluid ejection device. 
         FIGS.  3 A and  3 B  are block diagrams that illustrate some components of an example fluid ejection device. 
         FIG.  4    is a flowchart that illustrates an example sequence of operations that may be performed by an example fluid ejection device. 
         FIG.  5    is a flowchart that illustrates an example sequence of operations that may be performed by an example fluid ejection device. 
         FIG.  6    is a flowchart that illustrates an example sequence of operations that may be performed by an example fluid ejection device. 
         FIG.  7    is a flowchart that illustrates an example sequence of operations that may be performed by an example fluid ejection device. 
         FIG.  8    is a flowchart that illustrates an example sequence of operations that may be performed by an example fluid ejection device. 
     
    
    
     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. 
     DESCRIPTION 
     Examples of fluid ejection devices may comprise at least one fluid ejection die. Example fluid ejection dies may comprise a plurality of ejection nozzles that may be arranged in a set, where such plurality of nozzles may be referred to as a set of nozzles. In some examples, each nozzle may comprise a fluid chamber, a nozzle orifice, and a fluid ejector. A fluid ejector may include a piezoelectric membrane based actuator, a thermal resistor based actuator (which may be referred to as a thermal fluid ejector), an electrostatic membrane actuator, a mechanical/impact driven membrane actuator, a magneto-strictive drive actuator, or other such elements that may cause displacement of fluid responsive to electrical actuation. Furthermore, example fluid ejection dies may comprise at least one temperature sensor disposed thereon. In some examples, a fluid ejection die may comprise at least one temperature sensor for each set of nozzles. In some examples, a fluid ejection die may comprise at least one temperature sensor for each nozzle. 
     In such examples, for a respective nozzle, an actuation signal may be transmitted to the respective nozzle to cause actuation of a fluid ejector disposed in the respective nozzle. Due to actuation of the fluid ejector, the nozzle may eject a drop of fluid. As used herein, an ejection event may refer to the actuation and subsequent ejection of at least one fluid drop from at least one nozzle. Moreover, it may be noted that in some examples, a plurality of nozzles may be actuated concurrently such that a plurality of fluid drops may be ejected concurrently. Accordingly, in these examples, an ejection event refers to the concurrent actuation and ejection of fluid drops from a plurality of respective nozzles. 
     In some example fluid ejection systems, as fluid is ejected via nozzles, a temperature change may occur. For example, if fluid ejectors of the nozzles correspond to thermal fluid ejectors, a temperature of a fluid ejection die may increase responsive to actuation of the thermal fluid ejector. In addition, when fluid drops are ejected from the nozzle, a temperature decrease/cooling effect may occur. Accordingly, an ejection event for a fluid ejection die may facilitate a temperature change of the fluid ejection die. In addition, a volume of fluid ejected for a particular nozzle (i.e., a size of a fluid drop) may correspond to the cooling effect achieved by the ejection action. Therefore, due to the actuation of the fluid ejector and/or the ejection of a fluid drop, a temperature associated with the nozzle may change in an expected manner. Furthermore, a temperature change may further include a rate of change of the temperature of a nozzle or a set of nozzles over time. In other examples, a temperature change may include a rate of change of the temperature of a nozzle or a set of nozzles over a number of ejection events. 
     Example fluid ejection devices may include a control engine, where the control engine may monitor temperatures of the nozzles of the fluid ejection die during operation of the fluid ejection die. Based on the temperature of the nozzles associated with ejection events, the control engine may determine nozzle characteristics for nozzles of the fluid ejection die. In some examples, a nozzle characteristic that may be determined may include an operational status of at least one respective nozzle, where an operational status may include whether a nozzle is operative or non-operative. In some examples, a nozzle characteristic that may be determined may include a volume of fluid ejected for fluid drops of at least one ejection event. In some examples, a nozzle characteristic that may be determined may include whether at least one respective nozzle is at least partially blocked. These and other nozzle characteristics may be determined as described herein. 
     As shown herein, example fluid ejection devices may comprise engines, where such engines may be any combination of hardware and programming to implement the functionalities of the respective engines. In some examples described herein, the combinations of hardware and programming may be implemented in a number of different ways. For example, the programming for the engines may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the engines may include a processing resource to process and execute those instructions. 
     In some examples, a fluid ejection device implementing such engines may include the machine-readable storage medium storing the instructions and the processing resource to process the instructions, or the machine-readable storage medium may be separately stored and accessible by the system and the processing resource. In some examples, engines may be implemented in circuitry. Moreover, processing resources used to implement engines may comprise a processing unit (CPU), an application specific integrated circuit (ASIC), a specialized controller, and/or other such types of logical components that may be implemented for data processing. 
     Some examples contemplated herein may compare temperatures and/or temperature changes associated with nozzles of a fluid ejection die to an expected temperature or an expected range of temperatures. In such examples, at least one nozzle characteristic of at least one respective nozzle may be determined based at least in part on whether temperature and/or temperature changes associated with the at least one nozzle are within an expected range. An expected temperature or an expected temperature range may be predefined, or such expected temperature or expected temperature range may be determined by the device during performance of operations by the device. 
     For example, temperatures of a nozzle may be monitored during ejection of fluid drops with the nozzle for a set of 10 ejection events. Based on previous performances of the set of 10 ejection events, examples may have an expected range of temperature changes that occur for nozzles when performing the 10 ejection events. In other examples, an example fluid ejection device may have an expected temperature change range for a given duration when performing ejection events, such as one minute. In such examples, the fluid ejection device may compare a measured temperature change over one minute to the expected temperature change range. In some examples, the fluid ejection device may determine nozzle characteristics based at least in part on a rate of change of a temperature associated with a nozzle. In such examples, an expected rate of change of a temperature associated with a nozzle may be compared to a determined rate of change for the nozzle during one ejection event or a set of ejection events when determining nozzle characteristics. These and other similar examples are contemplated herein. 
     Turning now to the figures, and particularly to  FIG.  1   , this figure provides a block diagram that illustrates some components of an example fluid ejection device  10 . As shown, the fluid ejection device may comprise at least one fluid ejection die  12 . The at least one fluid ejection die  12  may comprise nozzles  14  and at least one temperature sensor  16 . In addition, the fluid ejection device  10  further comprises a control engine  24 . As described previously, the control engine  24  may monitor temperature of the nozzles  14  during ejection events with the temperature sensors  16 , and the control engine  24  may determine nozzle characteristics of nozzles  14  based at least in part on the temperature. 
       FIG.  2    provides a block diagram that illustrates some components of an example fluid ejection device  50 . In this example, the fluid ejection device  50  may comprise fluid ejection dies  54 . Each fluid ejection die  54  comprises nozzles  56  with fluid ejectors  58  disposed therein, and the fluid ejection dies  54  further comprise at least one temperature sensor  60 . As described in previous examples, the fluid ejection device  50  further comprises a control engine  66 . As shown, the control engine may comprise at least one processing resource  68  and at least one memory resource  70  that stores executable instructions  72 . Execution of instructions  636  may cause the processing resource  68  and/or fluid ejection system  50  to perform functionalities, processes, and/or sequences of operations described herein. Notably, the memory resource  70  may be non-transitory. 
     The control engine  66  may monitor temperatures associated nozzles  56  with the temperature sensors  60  thereof. Based at least in part on the temperatures associated with the nozzles of the fluid ejection dies  54  associated with at least one ejection event, a temperature change associated with nozzles  56  actuated for the at least one ejection event may be determined. Based on such temperature changes, nozzle characteristics of at least one respective nozzle  56  may be determined. 
       FIGS.  3 A-B  provide block diagrams that illustrate some components of an example fluid ejection device  100 . In these examples, the fluid ejection device  100  comprises nozzles  102 , where each nozzle includes an ejection chamber  104 , a fluid ejector  106  disposed in the ejection chamber  104 , and a nozzle orifice  106  formed in a portion of the ejection chamber  104 . Examples described herein may include thermal fluid ejectors, such that actuation of a respective fluid ejector  106  of a respective nozzle  104  may cause formation of a vapor bubble proximate the fluid ejector  106 . The vapor bubble may cause displacement of fluid in the ejection chamber  104  such that the displaced fluid may be ejected via the nozzle orifice  108  as a fluid drop. As mentioned previously, actuation of the respective fluid ejector  106  may cause a temperature increase in the respective nozzle  102 . 
     In the example of  FIG.  3 A , the fluid ejection device  100  includes a respective temperature sensor  110  positioned proximate each respective nozzle  102 . Accordingly, in this example, a control engine  112  of the fluid ejection device  100  may monitor a temperature of each nozzle  102  with at least the respective temperature sensor  110  disposed proximate the respective nozzle  102 . In some examples, the control engine may further determine a temperature for a respective nozzle  102  based at least in part on temperatures sensed by temperature sensors  110  disposed proximate neighboring nozzles  102 . Accordingly, as described herein, a temperature associated with a respective nozzle  102  may correspond to a temperature sensed by a temperature sensor  110  disposed proximate the respective nozzle  102 . In the example of  FIG.  3 B , the fluid ejection device comprises a temperature sensor  110  for a group of neighboring nozzles  102 . Accordingly, in this example, a temperature associated with a respective nozzle  102  may be monitored and determined by the respective temperature sensor  110  for the group of neighboring nozzles  102 . The examples of  FIGS.  3 A and  3 B  are provided to illustrate example configurations of nozzles and temperature sensors. Other examples may include various other arrangements of nozzles and temperature sensors, where such other examples may include more or less temperature sensors per nozzle. 
       FIGS.  4 - 7    provide flowcharts that provide example sequences of operations that may be performed by an example fluid ejection device and/or a processing resource thereof to perform example processes and methods. In some examples, the operations included in the flowcharts may be embodied in a memory resource (such as the example memory resource  70  of  FIG.  2   ) in the form of instructions that may be executable by a processing resource to cause the an example fluid ejection device and/or a control engine thereof to perform the operations corresponding to the instructions. Additionally, the examples provided in  FIGS.  4 - 7    may be embodied in device, machine-readable storage mediums, processes, and/or methods. In some examples, the example processes and/or methods disclosed in the flowcharts of  FIGS.  4 - 7    may be performed by one or more engines. Moreover, performance of some example operations described herein may include control of components and/or subsystems of the fluid ejection device by a control engine thereof to cause performance of such operations. For example, ejection of fluid drops with a fluid ejection die of the device may include control of the fluid ejection die by the control engine to cause such ejection of fluid drops. 
     Turning now to  FIG.  4   , this figure provides a flowchart  150  that illustrates an example sequence of operations that may be performed by an example fluid ejection device. The fluid ejection device may eject fluid drops with a nozzle or a set of nozzles of a fluid ejection die for at least one ejection event (block  152 ). During ejection of the fluid drops, the fluid ejection device may monitor temperatures associated with the nozzle or set of nozzles with temperature sensors of the fluid ejection die (block  154 ). Based at least in part on temperature changes of temperatures associated with the nozzle corresponding to the at least one ejection event, the fluid ejection device may determine at least one nozzle characteristic of the nozzle (block  156 ). 
     For example, if a particular nozzle is actuated (i.e., the fluid ejector of the nozzle is electrically actuated) for a set of ejection events, an example fluid ejection device may monitor the temperature change of at least one temperature sensor disposed proximate the nozzle due to the actuation. As discussed previously, the temperature associated with the nozzle may increase due to actuation of the nozzle for ejection, and the temperature associated with the nozzle may decrease due to fluid drop ejection. Accordingly, over the set of ejection events for which the nozzle is actuated, a temperature change may occur. Based on the temperature change for the nozzle, the fluid ejection device may determine whether the nozzle is operative (e.g., ejecting fluid drops), whether the nozzle is partially or fully blocked, an average drop volume of the fluid drops ejected for the set of ejection events, and/or other such nozzle characteristics. 
       FIG.  5   , provides a flowchart  200  that illustrates an example sequence of operations that may be performed by an example fluid ejection device. In this example, fluid ejectors of nozzles of a fluid ejection die of the fluid ejection device may be actuated for at least one ejection event (block  202 ). A temperature change associated with each nozzle actuated for the at least one ejection event may be determined (block  204 ). A volume of fluid ejected for the at least one ejection event may be determined based at least in part on the temperature change associated with each nozzle (block  206 ). Based at least in part on the volume of fluid ejected for the at least one ejection event, examples herein may determine an operational status of the nozzles (block  208 ). 
     In this example, it may be appreciated that a plurality of nozzles may be actuated concurrently for one ejection event or a set of ejection events. Accordingly, in this example, the fluid ejection system may determine that some nozzles of the plurality ejected are non-operative without determining the specific nozzles. In other similar examples, the fluid ejection device may determine the operational status of specific nozzles by analyzing temperature changes associated with the nozzles for a set of ejection events in which different combinations of nozzles are ejected concurrently. In other examples, the fluid ejection device may determine the operational status of each nozzle based on a respective temperature change associated with the respective nozzle. 
       FIG.  6    provides a flowchart  250  that illustrates an example sequence of operations that may be performed by an example fluid ejection device. The fluid ejection device may monitor temperatures associated with nozzles of a fluid ejection die thereof for fluid ejection events (block  252 ). The fluid ejection device may compare the determined temperature change for a nozzle to an expected temperature change for the nozzle (block  254 ). If the temperature change for a respective nozzle is different than an expected temperature change (‘Y’ branch of block  254 ), the fluid ejection device may determine that the nozzle is non-operative (block  256 ). If the temperature change of a respective nozzle is approximate the expected temperature change (‘N’ branch of block  254 ), the example fluid ejection device may determine that the respective nozzle is operative (block  258 ). In some examples, the fluid ejection device may determine that a nozzle or a group of nozzles are non-operative if the temperature change is greater than an expected temperature change. As used herein, a temperature change for a respective nozzle or group of nozzles may be determined to be approximate an expected temperature change if the temperature change is within a range of ±10%. 
       FIG.  7    provides a flowchart  300  that illustrates a sequence of operations that may be performed by an example fluid ejection device. In some examples, the fluid ejection device may perform servicing operations associated with fluid ejection dies thereof. Some examples of servicing operations include nozzle ejection operations to reduce nozzle clogging, crusting, and/or other issues that may occur. In such examples, a servicing operation may define particular nozzles to be ejected in a specified order for a set of ejection events corresponding to the servicing operation. Accordingly, in these examples, the fluid ejection device may eject fluid drops via nozzles of fluid ejection dies thereof for a set of ejection events corresponding to the servicing operation with (block  302 ). The system may determine at least one nozzle characteristic for at least one nozzle based at least in part on the determined temperature change associated with the at least one nozzle (block  306 ). 
     Turning now to  FIG.  8   , this figure provides a flowchart  350  that illustrates an example sequence of operations that may be performed by an example fluid ejection device. The fluid ejection device may eject fluid drops with a nozzle or a set of nozzles of a fluid ejection die for at least one ejection event (block  352 ). During ejection of the fluid drops, the fluid ejection device may monitor temperatures associated with the nozzle or set of nozzles with temperature sensors of the fluid ejection die (block  354 ). Based at least in part on a rate of change of temperature associated with the nozzle corresponding to the at least one ejection event, the fluid ejection device may determine at least one nozzle characteristic of the nozzle (block  356 ). 
     Accordingly, examples provided herein may provide a fluid ejection device in which nozzle characteristics of nozzles of fluid ejection dies thereof may be monitored and determined based at least in part on measured temperatures associated with the nozzles. Moreover, examples described herein may monitor temperature changes for nozzles associated with ejection events. By monitoring temperature and temperature change with temperature sensors proximate nozzles, examples may determine characteristics and conditions of the nozzles. 
     The preceding 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. Many modifications and variations are possible in light of the description. In addition, while various examples are described herein, elements and/or combinations of elements may be combined and/or removed for various examples contemplated hereby. For example, the example operations provided herein in the flowcharts of  FIGS.  4 - 8    may be performed sequentially, concurrently, or in a different order. Moreover, some example operations of the flowcharts may be added to other flowcharts, and/or some example operations may be removed from flowcharts. In addition, the components illustrated in the examples of  FIGS.  1 ,  2 ,  3 A, and  3 B  may be added and/or removed from any of the other figures. Therefore, the foregoing examples provided in the figures and described herein should not be construed as limiting of the scope of the disclosure, which is defined in the Claims.