Patent Application
20210370668
Fluidic devices, such as fluidic dies, for example, include a nozzle layer (e.g., an SU8 layer) disposed on a substrate (e.g., silicon). A plurality of nozzles are formed in the nozzle layer, with each nozzle including a fluid chamber formed within the nozzle layer and a nozzle orifice extending from a surface of the nozzle layer to the fluid chamber and from which fluid drops may be ejected from the fluid chamber. Some example fluidic devices may be printheads, where a fluid within the fluid chambers may be ink.
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.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.
Examples of fluidic devices, such as fluidic dies, for instance, may include fluid actuators. Fluid actuators may include thermal resistor based actuators, piezoelectric membrane based actuators, electrostatic membrane actuators, mechanical/impact driven membrane actuators, magneto-strictive drive actuators, or other suitable devices that may cause displacement of fluid in response to electrical actuation. Example fluidic dies described herein may include a plurality of fluid actuators, which may be referred to as an array of fluid actuators. An actuation event or firing event, as used herein, may refer to singular or concurrent actuation of fluid actuators of a fluidic die to cause fluid displacement.
Example fluidic dies may include fluid channels, fluid chambers, orifices, fluid holes, and/or other features which may be defined by surfaces fabricated in a substrate and other material layers of the fluidic die such as by etching, microfabrication (e.g., photolithography), micromachining processes, or other suitable processes or combinations thereof. Some example substrates may include silicon based substrates, glass based substrates, gallium arsenide based substrates, and/or other such suitable types of substrates for microfabricated devices and structures.
As used herein, fluid chambers may include ejection chambers in fluidic communication with nozzle orifices from which fluid may be ejected, and fluidic channels through which fluid may be conveyed. In some examples, fluidic channels may be microfluidic channels where, as used herein, a microfluidic channel may correspond to a channel of sufficiently small size (e.g., of nanometer sized scale, micrometer sized scale, millimeter sized scale, etc.) to facilitate conveyance of small volumes of fluid (e.g., picoliter scale, nanoliter scale, microliter scale, milliliter scale, etc.).
In some examples, a fluid actuator may be arranged as part of a nozzle where, in addition to the fluid actuator, the nozzle includes a fluid chamber in fluidic communication with a nozzle orifice. The fluid actuator is positioned relative to the fluid chamber such that actuation of the fluid actuator causes displacement of fluid within the fluid chamber that may cause ejection of a fluid drop from the fluid chamber via the nozzle orifice. Accordingly, a fluid actuator arranged as part of a nozzle may sometimes be referred to as a fluid ejector or an ejecting actuator.
In one example nozzle, the fluid actuator comprises a thermal actuator, where actuation of the fluid actuator (sometimes referred to as “firing”) heats fluid within the fluid chamber to form a gaseous drive bubble therein, where such drive bubble may cause ejection of a fluid drop from the fluid chamber via the nozzle orifice (after which the drive bubble collapses). In one example, the thermal actuator is spaced from the fluid chamber by an insulating layer. In one example, a cavitation plate may be disposed within the fluid chamber, where the cavitation plate is positioned to protect material underlying the fluid chamber, including the underlying insulating material and fluid actuator, from cavitation forces resulting from generation and collapse of the drive bubble. In examples, the cavitation plate may be metal (e.g., tantalum). In some examples, the cavitation plate may be in contact with the fluid within the fluid chamber.
In some examples, a fluid actuator may be arranged as part of a pump where, in addition to the fluidic actuator, the pump includes a fluidic channel. The fluidic actuator is positioned relative to the fluidic channel such that actuation of the fluid actuator generates fluid displacement in the fluid channel (e.g., a microfluidic channel) to convey fluid within the fluidic die, such as between a fluid supply (e.g., fluid slot) and a nozzle, for instance. A fluid actuator arranged to convey fluid within a fluidic channel may sometimes be referred to as a non-ejecting actuator. In some examples, similar to that described above with respect to a nozzle, a metal cavitation plate may be disposed within the fluidic channel above the fluid actuator to protect the fluidic actuator and underlying materials from cavitation forces resulting from generation and collapse of drive bubbles within the fluidic channel.
Fluidic dies may include an array of fluid actuators (such as columns of fluid actuators), where the fluid actuators of the array may be arranged as fluid ejectors (i.e., having corresponding fluid ejection chambers with nozzle orifices) and/or pumps (having corresponding fluid channels), with selective operation of fluid ejectors causing fluid drop ejection and selective operation of pumps causing fluid displacement within the fluidic die.
Fluidic dies may include a nozzle layer (e.g., an SU8 photoresist layer) disposed on a substrate (e.g., a silicon substrate) with the fluid chamber and nozzle orifice of each nozzle being formed in the nozzle layer. In one example, the SU8 layer has first surface (e.g., a lower surface) disposed on the substrate (facing the substrate), a second surface (e.g., an upper surface) opposite the first surface (facing away from the substrate). In one example, the fluid chambers with a corresponding nozzle orifice extending through the nozzle layer from the upper surface to each fluid chamber, where fluid drops may be ejected from each fluid chamber via the corresponding nozzle orifice. The fluid may comprise any number of fluid types including ink and biological fluids, for example.
During operation of the fluidic die, operating conditions at the upper surface of the nozzle layer can impact ejection of fluid drops from the nozzles. For example, fluid (e.g., ink) may puddle on the upper surface about a nozzle orifice and interfere with ejection of fluid from such nozzle orifice or from adjacent nozzle orifices, where such puddling may be the result of nozzle operational issues, such as damage to the nozzle layer, for example. Surface temperatures of the nozzle layer may also impact fluid ejection and, in some cases, may result in solidification of fluids which can obstruct nozzle orifices or result in a variation in properties in ejected drops.
Present techniques for monitoring nozzle operating conditions include drop detection techniques (e.g., electrical and optical), and scanning printed output for defects, for example. However, drop detection techniques are limited in the types of defects that are detectable, and scanning printed output is time consuming and expensive. Thermal sensors may also be employed, but such sensors are locating in wiring layers below the nozzle layer such that sensed temperatures represent an approximation of surface temperatures based on known thermal characteristics of the overlying material.
According to examples of the present disclosure, conductive traces are disposed so as to be exposed at the upper surface of the nozzle layer (e.g., disposed on the upper surface or partially embedded within the nozzle layer), wherein an electrical property of the conductive traces (e.g., impedance) is indicative of surface conditions of the upper surface of the nozzle layer (e.g., temperature, and presence of fluid, particles, or other surface contaminants).
Nozzle layer 34 includes a plurality of nozzles formed therein, such as illustrated by nozzle 40, with each nozzle 40 including a fluid chamber 42 disposed within nozzle layer 34 and a nozzle orifice 44 extending through the nozzle layer 34 from upper surface 35 to fluid chamber 42. In one example, substrate 32 includes a plurality of fluid feed holes 38 to supply fluid 39 (e.g., ink) from a fluid source to fluid chambers 42 of nozzles 40 (as illustrated by the arrows in
As described above, during operation, surface conditions at the upper surface 35 of nozzle layer 34 may adversely impact ejection of fluid drops 46 from nozzles 40. In one example, fluidic die 30 includes a conductive trace 50 disposed so as to be exposed to the upper surface 35 of nozzle layer 34, where an electrical property of conductive trace 50 of an operating condition at upper surface 35. In one case, an impedance of conductive trace 50 is periodically measured, where the measured impedance of conductive trace 50 is indicative of fluid puddling on upper surface 35 (e.g., a measured impedance value less than an expected value). In another case, the measured impedance of conductive trace 50 is indicative of a temperature of upper surface 35 of nozzle layer 34 (e.g., conductive trace 50 comprises a thermal resistor having a temperature dependent resistance). While described primarily in terms of an impedance, it is noted that, in other examples, a resistance of conductive trace 50 may be monitored to determine a surface operating condition.
In one example, as illustrated in
In one example, control logic 60 may be electrically connected to conductive trace 50 for monitoring the corresponding electrical property thereof. In one example, control logic 60 may be external to fluidic die 30 (e.g., as part of a printer controller), as indicated by the dashed lines in
By periodically monitoring an electrical property of a conductive trace 50 which is exposed at upper surface 35 of nozzle layer 34, an operating condition at upper surface 35, such as the presence of fluid puddling and temperature, for example, can be monitored in real time. Such real time monitoring enables early detection of potential damage and malfunctioning of fluidic die 30, thereby enabling defective components to be quickly identified and addressed which, in-turn, reduces downtime and potentially reduces an amount of defective output (e.g., printed output).
With reference to
With reference to
As described above, if nozzle layer 34 becomes damaged, such damage may adversely impact the ability of nozzles 40 to properly eject fluid drops 46, and may cause leakage and puddling of fluid 39 on upper surface 35 of fluidic die 30. Fluid puddling may also result from a particle or other obstruction on upper surface 35 interacting or interfering with ejected fluid drops 46, and from unsuitable operating conditions (e.g., improper power provided to a fluid actuator or improper actuation timing).
According to the example of
In one example, control logic 60 monitors an impedance of conductive trace 50 by injecting a fixed current through conductive trace 50 with a resulting voltage being representative of the impedance. In other cases, control logic 60 applies a fixed voltage to conductive trace 50 with a resulting current being representative of the impedance of conductive trace 50. In one example, control logic 60 may compare the measured impedance of conductive trace 50 to a set of known impedances which correlate to a temperature of conductive trace 50 and, thus, to a temperature at surface 35 of nozzle layer 34. In another case, control logic 60 may compare the measured impedance of conductive trace 50 to a set of known impedances indicative of fluid puddling on upper surface 35 and, in one example, indicative of a particular nozzle about which the fluid is puddling.
In the example of
According to one example, in operation, control logic 60 injects a fixed sense current, Is, through conductive trace 50 and measures a resulting sense voltage, Vs, across conductive trace 50 to measure the impedance thereof. According to one example, control logic 60 compares the measured impedance of conductive trace 50 to a set of known values of conducive trace 50, where a measure impedance within a first range of known impedances is indicative of a temperature of conductive trace 50, and thus a temperature at upper surface 35 of nozzle layer 34, and a measured impedance with a second range of known impedances is indicative of whether fluid puddling is present on upper surface 35 (see
During periodic monitoring, when control logic 60 impresses a known sense current, Is, through conductive trace 50, in addition to flowing through lateral segment 50c beyond the final nozzle orifice 44a, the sense current will also flow between first and second longitudinal segments 50a and 50b via puddle 62, as indicated by the arrow Is'. As a consequence, the resulting sense voltage, Vs, across conductive trace 50 as measured by control logic 60 will be less than an expected value, such that the measured impedance will be less than an expected value, indicating that a puddle is present about at least one of the nozzle orifices 44. In one example, based on a magnitude of measured impedance, control logic 60 can determine the nozzle orifice 44 about which puddle 62 has formed.
In other examples, conductive trace 50 can be employed to check an operation of selected nozzles 40. For instance, with additional reference to
With reference to
In the example implementations of
With reference to
It is noted that the configurations of
At 104, method 100 includes monitoring an impedance of the conductive trace, the impedance indicative of a surface condition at the upper surface of the nozzle layer, such as control logic 60 monitoring an impedance value of conductive trace 50 of
Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/016083 | 1/31/2019 | WO | 00 |
