Methods for photo-curing photo-sensitive material for printing and other applications
Methods and systems for forming objects through photo-curing of a liquid resin in a tank by selective exposure (through a mask) to radiation, in which during printing operations the liquid resin in the tank is displaced relative to the build area along an axis orthogonal to that along which the object is extracted from the liquid resin in the tank. A volume of the photo-curing liquid resin may be cycled through a cooling arrangement by being extracted from the tank, cooled, and then reintroduced into the tank as printing of the object is taking place. The mask is preferably one in which charged colorant particles are dispersed in an optically transparent fluid within a plurality of bi-state cells.
1. A method, comprising:
controlling a light source and a mask so as to form a first layer of photo-cured liquid resin of an object by passing light through a telecentric lens system towards and through the mask while various ones of pixels of the mask are biased to be transparent or opaque, the object located within a tank containing a photo-curing liquid resin, the tank including a tank opening, and the tank opening sealed by a radiation-transparent flexible member;
controlling a height adjustor so as to displace an extractor plate, and through the displacement of the extractor plate to further displace the object coupled to the extractor plate, along a first axis, with respect to a first surface of the radiation-transparent flexible membrane facing into the tank;
controlling the light source and the mask so as to form a second layer of photo-cured liquid resin of the object by passing light through the telecentric lens system towards and through the mask while the various ones of pixels of the mask are biased to be transparent or opaque; and
controlling a pumping arrangement to circulate a volume of the photo-curing liquid resin through the tank while forming said first and second layers of photo-cured liquid resin of the object such that the photo-curing liquid resin is introduced into the tank through a first sidewall opening and is extracted from the tank through a second sidewall opening distinct from the first sidewall opening,
wherein the first sidewall opening and the second sidewall opening are located on opposite lateral sides of the tank defining a shortest lateral dimension of the tank, and
wherein the pumping arrangement is configured to circulate the volume of the photo-curing liquid resin across the shortest lateral dimension of the tank and in a direction orthogonal to the first axis.
2. The method of claim 1 , further comprising cooling, with a cooling arrangement, the volume of the photo-curing liquid resin after it has been extracted from the tank through the second sidewall opening and before it is introduced into the tank through the first sidewall opening.
3. The method of claim 2 , wherein the cooling arrangement comprises a length of tubing for transporting the volume of the photo-curing liquid resin, the length of tubing being in contact with a heat sink.
4. The method of claim 3 , wherein the pumping arrangement includes a peristaltic pump in contact with the length of tubing and a reservoir for storing the photo-curing liquid resin.
5. The method of claim 2 , wherein the cooling arrangement comprises a Peltier element.
6. The method of claim 1 , further comprising:
receiving a temperature measurement of the photo-curing liquid resin in a build area of the tank; and
controlling the pumping arrangement to circulate the volume of the photo-curing liquid resin through the tank at a rate that is responsive to the measured temperature.
7. The method of claim 6 , wherein the temperature measurement is received from a temperature sensor disposed in the tank.
8. The method of claim 6 , wherein the temperature measurement is received from a thermal imaging device oriented to observe the build area through the mask.
9. The method of claim 8 , wherein the mask is a liquid crystal display (LCD) panel disposed adjacent to the tank opening.
10. The method of claim 1 , further comprising:
monitoring using a thermal imaging device the first and second layers of photo-cured liquid resin; and
altering an intensity of radiation from the light source in response to the monitoring.
11. The method of claim 10 , wherein the intensity of radiation is altered using one or more light filters.
12. The method of claim 10 , wherein altering the intensity of radiation comprises varying an exposure time.
13. The method of claim 10 , wherein altering the intensity of radiation comprises varying an exposure intensity.
14. The method of claim 10 , wherein altering the intensity of radiation comprises varying an exposure wavelength.
15. The method of claim 1 , further comprising:
monitoring using a thermal imaging device the first and second layers of photo-cured liquid resin; and
based on the monitoring, detecting possible points of failure in the object being formed.
16. The method of claim 1 , further comprising cooling an underside of the mask using a cooling arrangement.
17. The method of claim 16 , wherein cooling the underside of the mask comprises blowing chilled air on the underside of the mask.
18. The method of claim 1 , wherein the light source is configured to emit collimated ultraviolet light towards the tank opening and through the mask.
19. The method of claim 1 , wherein the first sidewall opening and the second sidewall opening face one another.
20. The method of claim 1 , wherein the first sidewall opening and the second sidewall opening are disposed at an identical vertical elevation as one another.