Patent Application
20080149024
This invention relates generally to the field of digitally controlled printing devices, and in particular to alignment of components that make up these devices.
Liquid ejection devices that include one or more alignment features are known, see, for example, U.S. Pat. No. 6,536,868 B1, issued on Mar. 25, 2003, to Kawamura et al. and U.S. Pat. No. 6,824,243 B1, issued on Nov. 30, 2004, to Yamaguchi et al.
U.S. Pat. No. 6,536,868 to Kawamura et al., issued Mar. 25, 2003, entitled “Liquid ejection type print head, printing apparatus provided with same and a method for producing a liquid ejection type print head,” discloses a print element unit. The print element unit includes a print element substrate, and a plate-like member having a surface to be adhered on which the print element substrate is positioned and fixedly adhered via heat-hardening adhesive. A first reference surface of the plate-like member is used as a positioning reference for the print element substrate. A holder member for holding tanks for storing liquid supplied to the print element substrate has a second reference surface that is engaged with the first reference surface of the plate-like member and with a reference surface of a mounting portion of a carriage member. When the second reference surfaces are engaged with the first surface, the print element unit and the holder member are fixedly adhered to each other via a hardening adhesive at a low (normal) temperature.
U.S. Pat. No. 6,824,243 to Yamaguchi et al., issued Nov. 30, 2004, entitled “Liquid jet print head and liquid jet printing apparatus,” discloses a liquid jet print head that includes a printing unit, a printing device substrate and a supporting substrate. Projections of the supporting substrate are used as a reference for positioning when the printing device substrate is attached to the supporting substrate and when the print head is installed in a carriage of a printer. Further, all reference portions used for positioning in the three-dimensional directions when installing the print head in the carriage are gathered in the printing unit.
Typically, the alignment features are formed in a plate, also referred to as a supporting member, to which the printing device substrate is attached to in these types of liquid ejection devices. The material used for the plate is usually a ceramic material that is expensive when compared to other materials such as plastic. As a consequence, the size and the complexity of the plate are kept to a minimum in order to reduce overall printhead cost. As a result, the distance between the alignment features is constrained. This may lead to alignment errors, for example, rotation alignment errors, when the printhead is mounted to the print carriage which can cause printed drop placement error ultimately resulting in reduced image quality.
As such, there is a need to reduce alignment errors associated with mounting of a printhead to a print carriage without significantly increasing printhead cost.
According to one feature of the invention, a marking assembly includes a substrate and a marking device. The substrate includes a first portion made from a first material and including a plurality of alignment features, and a second portion made from a second material affixed to the first portion of the substrate. The marking device is affixed to the second portion of the substrate and aligned to the alignment features of the first portion of the substrate.
According to another feature of the invention, a printer includes a marking assembly and a print carriage. The marking assembly includes a substrate and a marking device. The substrate includes a first portion made from a first material and including a plurality of alignment features, and a second portion made from a second material affixed to the first portion of the substrate. The marking device is affixed to the second portion of the substrate and aligned to the alignment features of the first portion of the substrate. The marking assembly is aligned to the print carriage with the plurality of alignment features of the first portion of the substrate.
According to another feature of the invention, a method of manufacturing a marking assembly includes providing a substrate including a first portion made from a first material and including a plurality of alignment features, and a second portion made from a second material affixed to the first portion of the substrate; positioning a marking device relative to the second portion of the substrate using the alignment features of the first portion of the substrate; and affixing the marking device to the second portion of the substrate.
In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings, in which:
The present description will be directed in particular to elements forming part of, or cooperating more directly with, apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art.
Referring to
A marking device 20 is affixed to second portion 16 of substrate 12 and is aligned to alignment features 18B, 18C of first portion 14 of substrate 12. In
Referring to
Using a ceramic material for second portion 16 of substrate 12 is advantageous because ceramic provides a mounting surface 26 for marking device 20 that is flat, stable, and thermally conductive. Using a plastic material for first portion 14 of substrate 12 is advantageous because plastic is much lower in cost when compared to other materials, for example, ceramic, particularly when first portion 14 of substrate 12 includes complex shapes. Accordingly, distances between alignment features 18B, 18C of substrate 12 can be increased when compared to alignment features formed in other materials, for example, ceramic, without significantly increasing printhead cost. Increasing the distances between alignment features 18B, 18C reduces alignment errors associated with printhead-print carriage mounting and results in reduced printed drop placement error during printer operation.
Other mechanical features can be incorporated, for example, molded into first portion 14 of substrate 12 when first portion 14 is made from a plastic material. In the example described with reference to
The materials selected for first portion 14 and second portion 16 of substrate 12 help to minimize thermal mechanical stress in marking device the silicon ejector die. When one or more of the materials selected include materials having high thermal conductive properties, heat dissipation is increased and may result in the elimination of a separate heat sink component.
First portion 14 is made from a first material and second portion 16 is made from a second material that have substantially similar thermal expansion coefficients. In the example described above, the ceramic material used for second portion 16 is 96% alumina and has a thermal coefficient of expansion (CTE) that is an adequate match to the silicon material used in ejector die 22. The plastic used for first portion 14 is glass filled plastic material, for example, Noryl GFN3 (30% glass filled), and has a thermal coefficient of expansion (CTE) that is an adequate match to the ceramic material of second portion 16. In addition to being an adequate CTE match, the plastic material of first portion 14 of substrate 12 was chosen to be a highly glass filled plastic to increase the mechanical strength of substrate 12 in order to minimize movement of the ceramic die mounting surface 26 during printhead manufacturing and use.
Second portion 16 of substrate 12 includes at least one fluid manifold 30 formed therein. Typically, fluid manifold 30 includes one or more fluid channels 32 (as shown in
Referring back to
Commonly referred to as datums, alignment features 18B, 18C are used when mounting printhead or mounting marking assembly 10 to a printer carriage of a printer (as shown in
Typically, alignment features 18B, 18C are projections molded into first portion 14 of substrate 12. The number, shape, and size of alignment features 18B, 18C can vary depending on the specific application contemplated. In
Second portion 16 of substrate 12 is accurately aligned with alignment features 18B, 18C of substrate 12 during the insert molding process. One or pins (not shown) are used in the mold to align second portion 16 to alignment features 18B, 18C of substrate 12. Typically, one or more indentations 36 are formed in first portion 14 of substrate 12 as a result of using one or more pins to align second portion 16 relative to alignment features 18B, 18C of substrate 12.
Referring to
Referring to
Referring to
Referring to
Reference features 48 each include surfaces 118B and 118C corresponding to alignment features 18B and 18C. As shown in
Using the same alignment features (or a single set of alignment features) for both purposes helps to reduce alignment errors associated with mounting marking assembly 10 to printer carriage 46 by reducing the number of sets of alignment features needed to affix ejector die 22 to substrate 12 and mount marking assembly 10 to printer carriage 46. Additionally, when compared to prior art devices, alignment errors associated with mounting marking assembly 10 to printer carriage 46 are also reduced due to the increased distances between alignment features 18B, 18C of substrate 12.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.
