Typewriting machines – Means auxiliary to typewriting function – Frame – casing – or support for typewriter
Reexamination Certificate
2000-01-28
2001-03-20
Hilten, John S. (Department: 2854)
Typewriting machines
Means auxiliary to typewriting function
Frame, casing, or support for typewriter
C400S691000
Reexamination Certificate
active
06203224
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to a color proofing apparatus and methods of manufacture and more particularly to a print engine chassis fabricated using sheet metal reinforced with castable polymer concrete.
BACKGROUND OF THE INVENTION
Pre-press color proofing is a procedure used by the printing industry for creating representative images of printed material. This procedure avoids the high cost and time required to produce printing plates and also avoids setting-up a high-speed, high-volume printing press to produce a representative sample, as a proof, of an intended image for printing. Otherwise, in the absence of pre-press proofing, a production run may require several corrections and be reproduced several times to satisfy customer requirements. This results in lost time and profits. By utilizing pre-press color proofing, time and money are saved.
A laser thermal printer having half-tone color proofing capabilities is disclosed in commonly assigned U.S. Pat. No. 5,268,708 titled “Laser Thermal Printer With An Automatic Material Supply” issued Dec. 7, 1993 in the name of R. Jack Harshbarger, et al. The Harshbarger, et al. device is capable of forming an image on a sheet of thermal print media by transferring dye from a roll of dye donor material to the thermal print media. This is achieved by applying thermal energy to the dye donor material to form the intended image on the thermal print media. This apparatus generally comprises a material supply assembly; a lathe bed scanning subsystem, which includes a lathe bed scanning frame, a translation drive, a translation stage member, a laser printhead; and a rotatable vacuum imaging drum; and exit sports for exit of thermal print media and dye donor material from the printer.
The operation of the Harshbarger, et al. apparatus comprises metering a length of the thermal print media in roll form from a material supply assembly. The thermal print media is then measured and cut into sheet form of the required length, transported to the vacuum imaging drum, registered, and then wrapped around and secured onto the vacuum imaging drum. Next, a length of dye donor roll material is also metered out of the material supply assembly, measured and cut into sheet form of the required length. The cut sheet of dye donor roll material is then transported to and wrapped around the vacuum imaging drum, such that it is superposed in registration with the thermal print media.
After the dye donor material is secured to the periphery of the vacuum imaging drum, the scanning subsystem and printhead exposes the thermal print media while the vacuum imaging drum rotates past the printhead. The translation drive then traverses the print head and translation stage member axially along the rotating vacuum imaging drum in coordinated motion with the rotating vacuum imaging drum to produce the intended image on the thermal print media.
Although the printer disclosed in the Harshbarger, et al. patent performs well, there is a long-felt need to reduce manufacturing costs for this type of printer and for similar types of imaging apparatus. With respect to the lathe bed scanning frame disclosed in the Harshbarger, et al. patent, the machined casting used as the frame represents significant cost relative to the overall cost of the printer. Cost factors include the design and fabrication of the molds, the casting operation, and subsequent machining needed in order to achieve the precision necessary for a lathe bed scanning engine used in a printer of this type.
Castings present inherent problems in modeling, making it difficult to use tools such as finite element analysis to predict the suitability of a design. Moreover, due to shrinkage, porosity, and other manufacturing anomalies, it is difficult to obtain uniform results when casting multiple frames. In the assembly operation, each frame casting must be individually assessed for its suitability to manufacturing standards and must be individually machined. Further, castings also exhibit frequency response behavior, such as to resonant frequencies, which are difficult to analyze or predict. For this reason, the task of identifying and reducing vibration effects can require considerable work and experimentation. Additionally, the overall amount of time required between completion of a design and delivery of a prototype casting can be several weeks or months.
The combined weight of the imaging drum, motor and encoder components, and print head translation assembly components, plus the inertial forces applied when starting and stopping the drum require a frame having substantial structural strength. For this reason, a sheet metal frame, by itself, would not provide a solution. Alternative methods used for frame fabrication have been tried, with some success. For example, welded frame structures have been used. However, these welded structures require significant expense in manufacture and do not provide the structural stability available from castings.
Alternatives to metal castings have been used by manufacturers of machine tools. In particular, castable polymers, manufactured under a number of trade names, have been employed to provide support structures that are at least equivalent to castings for apparatus such as machine tool beds and optical tables. These castable polymers also provide improved performance when compared with castings, with respect to expansion and contraction due to heat and with respect to vibration damping.
Castable polymers have been employed to provide substitute structures for metal castings and weldments. One example is disclosed in U.S. Pat. No. 5,415,610 (Schutz et al.) which discloses a frame for machine tools using castable concrete to form a single casting of a bed and a vertical wall for a machine tool. U.S. Pat. Nos. 5,678,291 (Braun) and 5,110,283 (Bluml et al.) are just two of a number of examples in which castable polymer concrete is used as a machine tool bed or for mounting guide rails in machining environments. Castable polymers are also used in the machine tool environment for damping mechanisms, as is disclosed in U.S. Pat. No. 5,765,818 (Sabatino et al.) In these and similar applications, castable polymer concrete is used to provide a substantial mass of material, such as for the bed of a machine tool. These patents do not disclose selective use of castable polymers to supplement a metal structure with additional structural integrity.
There has been a long-felt need to reduce the cost and complexity of printer fabrication without compromising the structural strength required for the lathe bed scanning assembly. However, up to this time, printer solutions have been limited to the use of conventional machined castings or weldments.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a reinforced sheet metal structure for a print engine chassis has high structural rigidity, is economical, and which can be manufactured easily.
According to one aspect of the present invention a print engine chassis supports a vacuum imaging drum and a printhead translation assembly. The chassis comprises a sheet metal frame of interlocking rigid members and a filler material which is poured into the sheet metal frame to provide rigidity at points where the rigid members interlock.
According to one embodiment of the present invention, sheet metal cut to form the interlocking rigid members have an arrangement of tabs and slots that allow the interlocking rigid members to be quickly assembled by hand to form the sheet metal frame of the chassis. A filler material, preferably of castable polymer concrete, is poured into selective cavities formed within the sheet metal frame formed by the rigid members.
An advantage of the present invention is that individual interlocking rigid members can be modified in order to change the design of the chassis, even to modify the size or configuration of the overall structure. This contrasts with methods using a casting, which cannot be easily modified or scaled dimensionally. This scalable feature is particularly benefi
Blish Nelson Adrian
Eastman Kodak Company
Hilten John S.
Nguyen Anthony H.
LandOfFree
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