Patent Application
20170151783
Inkjet technology is widely used for precisely and rapidly dispensing small quantities of fluid. Inkjet printheads eject drops of fluid, such as, for example, ink, from a nozzle by creating a short pulse of increased pressure within a firing chamber. During printing, this ejection operation can repeat thousands of time per second. One way to create pressure in the firing chamber is by heating the fluid in the firing chamber. A thermal inkjet (TIJ) device may include a heating element, such as, for example, a firing resistor, in the firing chamber. To eject a drop of the fluid, an electrical current may be passed through the heating element, and as the heating element generates heat, a portion of the fluid within the firing chamber may be vaporized. The vapor may rapidly expand, forcing a drop of fluid out of the firing chamber and through the nozzle. The electrical current across the heating element may then be turned off, allowing the heating element to cool. As the vapor bubble rapidly collapses, more fluid my be drawn into the firing chamber.
The detailed descriptive section references the drawings, wherein:
all in which various embodiments may be implemented.
Examples are shown in the drawings and described in detail below. The drawings are not necessarily to scale, and various features and views of the drawings may be shown exaggerated in scale or in schematic for clarity and/or conciseness. The same part numbers may designate the same or similar parts throughout the drawings.
There remains continued interest in increasing print speeds, print quality, and printing versatility. Among the solutions to increasing print speeds is increased printhead swath, but this solution may pose a cost challenge for printheads using an increased printhead silicon area to achieve the increased printhead swath. A solution to high-quality, versatile printing may include dual drop weight configurations including individual fluid chambers and associated nozzles having different drop volumes. For example, a printhead may include some fluid chamber/nozzle sets designed to eject drops having a smaller size than other ones of the fluid chamber/nozzle sets. While this configuration may allow for different drop characteristics for large and small drops from a single inkjet printhead, the print speed and nozzle density may be reduced given the nozzle redundancy.
Described herein are various implementations of a fluid ejection apparatus including a first firing resistor and a second firing resistor to selectively cause fluid to be ejected through a single nozzle, and a parasitic resistor arranged to add a parasitic resistance to the first firing resistor. In various implementations, the first firing resistor may produce a fluid drop having a first size and the second firing resistor may produce a fluid drop having a second size larger than the first size. In various ones of these implementations, the fluid ejection apparatus may include a single firing line arranged to provide a same firing voltage to the first firing resistor and the second firing resistor, and the parasitic resistor may operate to control an amount of energy, and associated stress, across the first firing resistor, which may increase the life of the first firing resistor as compared to apparatuses not including the parasitic resistor.
Turning now to
The printhead assembly 102 may include at least one printhead 114. The printhead 114 may include one or more printhead dies to supply a fluid, such as ink, for example, to a plurality of nozzles 116. At least one of the printhead dies may include a first firing resistor 122a and a second firing resistor 122b to selectively cause fluid to be ejected through a single one of the nozzles 116, and a parasitic resistor 123 arranged to add a parasitic resistance to the first firing resistor 122a, as described more fully herein.
The plurality of nozzles 116 may eject ejects drops of the fluid toward a print media 118 so as to print onto the print media 118. The print media 118 may be any type of suitable sheet or roll material, such as, for example, paper, card stock, transparencies, polyester, plywood, foam board, fabric, canvas, and the like. The nozzles 116 may be arranged in one or more columns or arrays such that properly sequenced ejection of fluid from nozzles 116 may cause characters, symbols, and/or other graphics or images to be printed on the print media 118 as the printhead assembly 102 and print media 118 are moved relative to each other.
The fluid supply assembly 104 may supply fluid to the printhead assembly 102 and may include a reservoir 120 for storing the fluid. In general, fluid may flow from the reservoir 120 to the printhead assembly 102, and the fluid supply assembly 104 and the printhead assembly 102 may form a one-way fluid delivery system or a recirculating fluid delivery system. In a one-way fluid delivery system, substantially all of the fluid supplied to the printhead assembly 102 may be consumed during printing. In a recirculating fluid delivery system, however, only a portion of the fluid supplied to the printhead assembly 102 may be consumed during printing. Fluid not consumed during printing may be returned to the fluid supply assembly 104. The reservoir 120 of the fluid supply assembly 104 may be removed, replaced, and/or refilled.
The mounting assembly 106 may position the printhead assembly 102 relative to the media transport assembly 108, and the media transport assembly 108 may position the print media 118 relative to the printhead assembly 102. In this configuration, a print zone 124 may be defined adjacent to the nozzles 116 in an area between the printhead assembly 102 and print media 118. In some implementations, the printhead assembly 102 is a scanning type printhead assembly. As such, the mounting assembly 106 may include a carriage for moving the printhead assembly 102 relative to the media transport assembly 108 to scan the print media 118. In other implementations, the printhead assembly 102 is a non-scanning type printhead assembly. As such, the mounting assembly 106 may fix the printhead assembly 102 at a prescribed position relative to the media transport assembly 108. Thus, the media transport assembly 108 may position the print media 118 relative to the printhead assembly 102.
The electronic controller 110 may include a processor 138, memory 140, firmware, software, and other electronics for communicating with and controlling the printhead assembly 102, mounting assembly 106, and media transport assembly 108. Memory 140 may include both volatile (e.g., RAM) and nonvolatile (e.g., ROM, hard disk, floppy disk, CD-ROM, etc.) memory components comprising computer/processor-readable media that provide for the storage of computer/processor-executable coded instructions, data structures, program modules, and other data for the printing system 100. The electronic controller 110 may receive data 130 from a host system, such as a computer, and temporarily store the data 130 in memory 140. Typically, the data 130 may be sent to the printing system 100 along an electronic infrared, optical, or other information transfer path. The data 130 may represent, for example, a document and/or file to be printed. As such, the data 130 may form a print job for the printing system 100 and may include one or more print job commands and/or command parameters.
In various implementations, the electronic controller 110 may control the printhead assembly 102 for ejection of fluid drops 117 from the nozzles 116. Thus, the electronic controller 110 may define a pattern of ejected fluid drops 117 that form characters, symbols, and/or other graphics or images on the print media 118. The pattern of ejected fluid drops 117 may be determined by the print job commands and/or command parameters from the data 130.
In various implementations, the printing system 100 is a drop-on-demand thermal inkjet printing system with a thermal inkjet (TIJ) printhead 114 suitable for implementing a printhead die 114 such that the firing resistors 122a/b thermally eject the fluid from the fluid chamber of the fluid ejection apparatus 100 through the respective nozzle 116. In some implementations, the printhead assembly 102 may include a single TIJ printhead 114. In other implementations, the printhead assembly 102 may include a wide array of TIJ printheads 114.
In various implementations, the printhead assembly 102, fluid supply assembly 104, and reservoir 120 may be housed together in a replaceable device such as an integrated printhead cartridge.
In addition to one or more printheads 114, inkjet cartridge 200 may include electrical contacts 205 and an ink (or other fluid) supply chamber 207. In some implementations, the cartridge 200 may have a supply chamber 207 that stores one color of ink, and in other implementations it may have a number of chambers 207 that each store a different color of ink. The electrical contacts 205 may carry electrical signals to and from a controller (such as, e.g., the electrical controller 110 described herein with reference to
As illustrated, the first firing resistor 122a and the second firing resistor 122b are arranged to receive the same firing voltage and the same firing pulse from the firing line 142. Select circuitry 144, which may operate by direct addressing, matrix addressing, or smart drive chip, may facilitate, at least in part, ejection of the fluid by the first firing resistor 122a and/or the second firing resistor 122b, by selectively opening or closing drive transistors 146a, 146b coupled between the selected resistor 122a, 122b, respectively, and ground, thereby allowing current to flow across the selected resistor. For example, the select circuitry 144 may select the first firing resistor 122a to fire, the second firing resistor 122b to fire, or both the first firing resistor 122a and the second firing resistor 122b to fire. Selection of which resistor to fire by the select circuitry 144 may be carried out by a processor (such as, e.g., the processor 138 described herein with reference to
In various implementations, the first firing resistor 122a and the second firing resistor 122b may have different resistances. For at least some of these implementations, the resistors 122a, 122b may be configured with differing resistances in order to produce fluid drops of differing sizes. For example, the first firing resistor 122a may be a low drop-weight resistor and the second firing resistor 122b may be a high drop-weight resistor, with the second firing resistor 122b having a resistance greater than a resistance of the first firing resistor 122a such that the second firing resistor 122b is to produce a fluid drop having a size larger than a fluid drop produced by the first firing resistor 122a. In various implementations, the differing resistances may be achieved by forming the first firing resistor 122a with an area/size greater than the area/size of the second firing resistors 122b.
In various implementations, producing fluid drops of differing sizes may allow the fluid ejection apparatus to produce images across a wider range of resolution, saturation, or speed, or a combination thereof. For example, printing using the low drop-weight first firing resistor 122a may produce smaller fluid drops to print with higher resolution, while printing using both the low drop-weight first firing resistor 122a and the high drop-weight first firing resistor 122b may eject a larger amount of fluid for higher speed printing or higher color saturation.
In the configuration shown in
where P is power, PW is pulse width, V is voltage across the resistor, Rbb is bulk resistance, R122 is the resistance of the resistor 122a or 122b, and Rparasitic is the parasitic resistance of resistor 122a or 122b. As such, introducing a parasitic resistance in the electrical path of the smaller first firing resistor 122a may reduce the energy delivered to the first firing resistor 122a when both the first firing resistor 122a and the second firing resistor 122b are fired simultaneously. The reduced energy may result in an increased life of the first firing resistor 122a than that experienced for configurations without the added parasitic resistance.
To increase the parasitic resistance of the first firing resistor 122a to control the energy delivered to the first firing resistor 122a when both the first firing resistor 122a and the second firing resistor 122b are fired simultaneously, the parasitic resistor 123 may be arranged in the electrical path of the first firing resistor 122a. In some of these implementations, the parasitic resistor 123 may have a resistance to reduce or eliminate R-life failure of the first firing resistor 122a. In some implementations, the parasitic resistor 123 may have a resistance smaller than the resistance of the first firing resistor 122a. For example, the parasitic resistor 123 may have a resistance about half that of the first firing resistor 122a. In some implementations, the first firing resistor 122a may have a resistance of about 100Ω and the parasitic resistor 123 may have a resistance of about 50Ω. In other implementations, the first firing resistor 122a and the parasitic resistor 123 may be configured with other resistances and other resistance ratios.
Turning now to
The substrate 450 may be a semiconductor substrate having doped regions, such as a doped region 460 and a doped region 462, and the thin-film stack 452 may be formed over the substrate 450. The thin-film stack 452 may include an oxide layer 464, a polysilicon layer 466 on the oxide layer 464, an insulating layer 468 over the patterned oxide layer 464 and polysilicon layer 466, a conductive layer 470 over the insulating layer 468, and insulating layer 472. The thin-film stack 452 may include multiple layers deposited on the substrate 450 in a pattern. The layers in the thin-film stack 452 can be deposited and patterned using known semiconductor deposition and processing techniques. It is to be understood that
A portion of the oxide layer 464 may form a gate oxide layer and a portion of the polysilicon layer 466 may form a gate of a drive transistor 446a. The doped regions 460 and 462 may form a source and drain of the drive transistor 446a. Other portions of the oxide layer 464 and the polysilicon layer 466 may form the parasitic resistor 423. Although the parasitic resistor 423 could be formed using a different material or materials, either on the substrate 450, s shown, or on another layer, forming the parasitic resistor 423 using the same polysilicon layer 466 used for forming the driver transistor 446a may have some benefits. Polysilicon may have a high sheet resistivity of about 28-30 Ω/sq and the process for forming the drive transistor 446a, or any other transistor on the substrate 450 during the same operation, generally has tight process controls for thickness, critical dimension (CD), and resistivity, and so forming the parasitic resistor 423 during the same operation may facilitate forming the parasitic resistor 423 with the desired resistance and footprint with tight process control. In addition, forming the parasitic resistor 423 under the dielectric layer 428 may result in the layers of the parasitic resistor 423 having less thermal impact and smaller surface adhesion impact on the barrier layer 456 in the downstream process operations than if the parasitic resistor 423 were located elsewhere. Furthermore, forming the parasitic resistor 423 of polysilicon may allow the parasitic resistor 423 to experience less leakage current, with the capability to carry enough current density during nozzle firing, than might be achieved if the parasitic resistor 423 were formed of another material.
The insulating layers 468, 472 may comprise any type of insulating layer, such as silicon oxide, phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), undoped silicate glass (USG), silicon carbide (SiC), silicon nitride (SiN), tetraethyl orthosilicate (TEOS), or the like, or combinations thereof. The insulating layers 468, 472 may comprise the same or different materials.
The conductive layer 470 may comprise any type of conductive layer or layers, such as tantalum (Ta), aluminum (Al), copper (Cu), tungsten (W), gold (Au), silicon (Si), or the like, or combinations thereof (e.g., Ta and Au), including alloys or combinations thereof (e.g., TaAl, AlCu, WSiN, AlCuSi, etc.). For example, conductive layers 482 and 484 are shown, and in some examples, the first conductive layer 482 may comprise WSiN and the second conductive layer 484 may comprise AlCu. In another example, the first conductive layer 482 may comprise TaAl and the second conductive layer 484 may comprise AlCu. Other combinations may be possible within the scope of the present disclosure.
In various implementations, the conductive layers 482, 484 may have different sheet resistances. For example, the conductive layer 482 may have a higher sheet resistance than the conductive layer 484 such that, where the conductive layer 484 is present, the majority of the current goes through the conductive layer 484. Thus, the conductive layer 484 may act as a conducting line and may be used to route signals, and the conductive layer 482 may act as a resistive line and may be used as a resistor. A portion of the conductive layer 482 may be exposed at the surface facing the fluid chamber 454, as shown, which may provide of surface of the first firing resistor 422a.
Conductive paths 476, 478, 480 may be formed in the insulating layer 468 to electrically couple the doped region 460 to the metal layer 470, the doped region 462 to the first resistor 422a, and the parasitic resistor 423 to the first resistor 422a, respectively, as shown.
Although the second firing resistor (see, e.g., second firing resistor 122b described herein with reference to
The conductive layer 474 may comprise any type of conductive layer or layers, similar to the conductive layer 470, such as, for example, Ta, Al, Cu, W, Au, Si, or the like, or combinations thereof (e.g., Ta and Au), including alloys or combinations thereof (e.g., TaAl, AlCu, WSiN, AlCuSi, etc.). As shown, for example, the conductive layer 474 may include a conductive layer 488 and a conductive layer 490. The conductive layer 490 may be used to provide a bond pad 492 for receiving electrical signals from an external source (not shown).
It is to be understood that the layers of the thin-film stack 452 may not be shown to scale. The layers may have various thicknesses depending on particular device configuration and processes used. In an example, the oxide layer 464 may have a thickness on the order of 750 Angstroms (A); the polysilicon layer 466 on the order of 3600 A; the dielectric layer 468 on the order of 13000 A; the metal layer 470 on the order of 5000 A; the dielectric layer 472 on the order of 3850 A; and the metal layer 474 on the order of 4600 A. These thicknesses are merely examples and other configurations may be possible.
Additionally, the particular configuration of layers in the thin-film stack 452 is also provided by way of example. It is to be understood that additional dielectric and/or metal layers may be provided in different configurations.
As shown in
Turning now to
The method 700 may proceed to block 703 with forming a first firing resistor and a second firing resistor over the substrate such that the parasitic resistor is electrically coupled to the first firing resistor to add a parasitic resistance to the first firing resistor. The firing resistors may be formed such that the parasitic resistor and/or drive transistor, and one more insulating layers, are between the firing resistors and the substrate. In various implementations, the substrate may comprise a semiconductor substrate and the method 700 may include doping the substrate, prior to forming the firing resistors, to form doped regions that provide source and drain regions of the drive transistor.
The method 700 may proceed to block 705 with forming a fluid chamber over the firing resistors, and then forming a nozzle fluidically coupled to the fluid chamber at block 707. The fluid chamber may be defined, at least in part, by a barrier layer and a nozzle plate layer. The nozzle may be formed in the nozzle plate layer.
Turning now to
The method 800 may proceed to block 811 with forming at least one insulating layer over the parasitic resistor and drive transistor, and then to block 813 with forming, in the at least one insulating layer, a first conductive path electrically coupled to the drive transistor and a second conductive path electrically coupled to the parasitic resistor.
The method 800 may proceed to block 815 with forming a first firing resistor and a second firing resistor over the substrate such that the parasitic resistor is electrically coupled to the first firing resistor to add a parasitic resistance to the first firing resistor. In various implementations, forming the first firing resistor may comprise forming the first firing resistor over the at least one insulating layer such that the first firing resistor is electrically coupled to the first conductive path and the second conductive path. In this configuration, the first firing resistor may be electrically coupled to the parasitic resistor and the drive transistor.
The method 800 may proceed to block 817 with forming a fluid chamber over the firing resistors, and then forming a nozzle fluidically coupled to the fluid chamber at block 819. The fluid chamber may be defined, at least in part, by a barrier layer and a nozzle plate layer. The nozzle may be formed in the nozzle plate layer.
Although certain implementations have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the implementations shown and described without departing from the scope of this disclosure. Those with skill in the art will readily appreciate that implementations may be implemented in a wide variety of ways. This application is intended to cover any adaptations or variations of the implementations discussed herein. It is manifestly intended, therefore, that implementations be limited only by the claims and the equivalents thereof.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2014/032834 | 4/3/2014 | WO | 00 |
