Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1999-05-03
2001-07-10
Grant, William (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S118000, C700S182000
Reexamination Certificate
active
06259962
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to three-dimensional modeling in general and to apparatus for controlling the build up of layers during three-dimensional printing.
BACKGROUND OF THE INVENTION
Three-dimensional (3-D) printing, which works by building parts in layers, is a process used for the building up of three-dimensional models. 3-D printing is relatively speedy and flexible allowing for the production of prototype parts and tooling directly from a CAD model, for example.
Using 3-D printing enables the manufacturer to obtain a full 3-D model of any proposed product before tooling thereby possibly substantially reducing the cost of tooling and leading to a better synchronization between design and manufacturing. A lower product cost and improved product quality can also be obtained.
Various systems have been developed for computerized three-dimensional printing. Known systems include a system developed by 3D Systems Inc. of California, USA, which operates on the basis of stereo-lithography wherein a focused ultra-violet laser is scanned over the top of a bath of photopolymerizable liquid polymer plastic material. The surface of the bath is polymerized on contact with the UV laser creating a solid plastic layer at or just below the surface.
U.S. Pat. No. 5,387,380 to Cima et al. describes a technique for providing layered parts by depositing a layer of powder material and then depositing a binder material in selected regions to produce a layer of bonded powder material at the selected regions. These steps are repeated for successive layers to form a desired component. Following heat treatment, unbound powder is removed, leaving the fabricated part.
U.S. Par. No. 5,287,435 to Cohen et al describes apparatus for producing three-dimensional models which includes apparatus for depositing layer-by-layer, a photopolymer material in a selectable configuration and apparatus for curing each layer prior to deposition of the succeeding layer.
A disadvantage of this system is that it is difficult to achieve a flat uniform surface for each layer. U.S. Pat. No. 5,287,435 utilizes a machining unit for trimming the surface of each layer to remove excessive thickness.
In standard two-dimensional printing, the ink jet printer prints parallel ink dot lines on a substrate by displacing its print head relative to a substrate in one direction during the actuation of its ink jet heads.
In order to print an image of a desired line resolution, each ink jet head is required to print a number of ink dot lines equal to the ratio between the separation gap between ink jet heads and the desired line resolution. In practice, this is achieved by intermittently advancing the print head relative to a substrate in a second direction perpendicular to the first direction through one or more steps and actuating the ink jet nozzles at each of their new positions whilst displacing the print head relative to a substrate in the first direction. Unfortunately, if one or more nozzles are blocked, the image will be imperfect, having unprinted bands.
Patent WO 97/31781 assigned to Idanit Technologies Ltd of Israel describes a method for operating an ink-jet printer, having a linear row of nozzles, which displaces the print head relative to the substrate in a direction which is transverse to the line being printed and repeating the printing steps. This method reduces the visual effect of an unprinted band due to a blocked nozzle by the displacement of the print head but does not compensate for the blocked nozzle completely.
SUMMARY OF THE INVENTION
The present invention provides a 3-D printing system for constructing 3-D models using a printing head having at least one row of ink-jet nozzles for ejecting interface material.
It is a further object of the invention to provide a method of printing 3-D models which is unaffected by the blockage of any of the nozzles.
It is a yet further object of the invention to provide a system and method for compensating for over and under deposition from any of the nozzles.
There is thus provided, in accordance with a preferred embodiment of the present invention, apparatus for three-dimensional printing of a three-dimensional model. The apparatus includes a printing head having a plurality of nozzles, a dispenser connected to the printing head for selectively dispensing interface material in layers and curing means for optionally curing each of the layers deposited. The depth of each deposited layer is controllable by selectively adjusting the output from each of the plurality of nozzles.
Furthermore, in accordance with a preferred embodiment of the present invention, the control means includes a dispenser connected to the printing head, a process controller coupled to the printing head and a Computer Aided Design (CAD) system coupled to the process controller.
Furthermore, in accordance with a preferred embodiment of the present invention, the plurality of nozzles includes an array of nozzles.
In addition, in accordance with a preferred embodiment of the present invention, the apparatus further includes positioning apparatus coupled to the process controller for selectively positioning the printing head by commands from the process controller.
Furthermore, in accordance with a preferred embodiment of the present invention, the interface material is a photopolymer material curable by the application of ultra-violet or infra red radiation.
In addition, in accordance with a preferred embodiment of the present invention, the apparatus further includes a reference sensor coupled to the process controller, sensor positioning apparatus coupled to the process controller for positioning the sensor; and means for calculating the variation in the height of the deposited layer from each of the nozzles.
There is thus provided, in accordance with a preferred embodiment of the present invention, a method for three-dimensional printing of a three-dimensional model. The method includes the steps of:
positioning a printing head to a first pre-selected position, the printing head having a plurality of nozzles along a longitudinal axis;
selectively dispensing interface material in layers from the printing head;
re-positioning the printing head to a second pre-selected position; and
repeating the step of selective dispensing.
The second pre-selected position is displaced axially along the longitudinal axis from the first pre-selected position.
In addition, in accordance with a preferred embodiment of the present invention, the method further includes the step of:
selectively adjusting the output from each of the plurality of ink-jet nozzles to control the amount of the interface material dispensed from each of the plurality of nozzles.
In addition, in accordance with a preferred embodiment of the present invention, the interface material is a photopolymer material and the method further includes the step of curing the deposited layers by the application of ultra-violet radiation or infra red radiation.
The method further includes the step of calibrating the nozzles.
Furthermore, in accordance with a preferred embodiment of the present invention, the step of calibrating includes the steps of:
depositing a single layer by selectively dispensing interface material from all of the nozzles;
comparing the height of the deposit from each of the nozzles with a reference level;
calculating the variation from the reference level; and
adjusting the dispensing of the interface material from each of the nozzles.
Furthermore, in accordance with a preferred embodiment of the present invention, the method further includes the step of compensating for a variation in each of the layers prior to depositing the succeeding layer.
In addition, the step of compensating includes the steps of:
comparing the height of the last deposited layer with a reference level;
calculating the variation from the reference level;
adjusting the dispensing of the interface material from each of the nozzles.
Additionally, in accordance with a preferred embodiment of the present invention, the step of comparing includes the ste
Bahta Kidest
Eitan Pearl Latzer & Cohen-Zedek
Grant William
Objet Geometries Ltd.
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