Patent Description:
The present invention relates to a photocuring three-dimensional molding system for 3D printing, and in particular it relates to a vat heating device suitable for use in the above system.

3D-printing (3DP), also known as additive manufacturing (AM), has been widely used in many fields such as mechanics, biomedicine, aerospace, etc. in recent years. 3D-printing can not only reduce costs, but it also has the tendency to replace existing processes, and it is thereby becoming a manufacturing technology for the new generation. Among the various 3D-printing technologies, the stereo-lithography apparatus (SLA) best meets the manufacturing accuracy and cost requirements. Therefore, in recent years, stereo-lithography technology has occupied a considerable market share in 3D-printing technology.

The photocuring molding technology uses a photosensitive resin as the material, and irradiates the photosensitive resin with ultraviolet light to generate a polymerization reaction, thereby curing and constructing a resin layer. Then, the cured resin layer is separated by a motor, and the platform is displaced to the next layer to cure the resin thereon. The steps of exposing, curing and separating are repeated to construct the printed.

In photocuring technology, temperature is one of the most important factors affecting the reaction efficiency and the quality of the molded product. For example, the temperature has a great influence on the viscosity of the resin. The resin to be cured is separated from the bottom of the vat in the above separation step. Thus, if the viscosity of the resin is too high, the drag force of the colloidal flow is too large, which will cause the cured product on the platform to fall off, resulting in the reduced printing yield of the machine. Therefore, how to control the reaction temperature of the photocuring molding technology to obtain a molded product with high yield and high chemical stability is an important issue.

<CIT> discloses a build plate for a three-dimensional printer includes: a rigid, optically transparent, gas-impermeable planar base having an upper surface and a lower surface; and a flexible, optically transparent, gas-permeable sheet having an upper and lower surface, the sheet upper surface comprising a build surface for forming a three-dimensional object, the sheet lower surface positioned on the base upper surface. The build plate includes a gas flow enhancing feature configured to increase gas flow to the build surface.

<CIT> discloses a vat heating device comprising: a vat having a bottom plate and used to accommodate a photosensitive resin, a heater disposed on the bottom plate and adjacent to the photosensitive resin to heat the photosensitive resin wherein the heater is a transparent conductive glass and is on an optical path of a light source for curing the photosensitive resin.

In the prior art, in order not to affect the optical path of the light source, the heating device of the photocuring molding system is usually disposed at the peripheral component outside of the vat. As such, the photosensitive resin within the vat is indirectly heated by the heating device through the vat. The above heating mechanism has to be used through the component with poor thermal conductivity such as the vat, which leads to shortcomings such as poor heating efficiency, uneven temperature of the resin, etc. Therefore, a novel vat heating device of the photocuring three-dimensional molding system, which can directly and effectively control the reaction temperature of the photosensitive.

The present invention provides a vat heating device according to claim <NUM>.

According to some embodiments, the present invention may provide a photocuring three-dimensional molding system, including a carrier, a vat, a heater, a platform, and a scanner. The vat is disposed on the carrier and has a bottom plate. The vat is used to accommodate a photosensitive resin. The heater is disposed on the bottom plate, adjacent to the photosensitive resin. The heater is used to heat the photosensitive resin. the platform is disposed over the vat. The scanner is disposed below the carrier. The scanner projects a light that passes through the carrier, the vat, and the heater to irradiate and cure the photosensitive resin inside the vat.

It should be noted that, in accordance with the standard practice in the industry, various features are not drawn to scale.

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact.

Furthermore, spatially relative terms, such as "beneath," "below," "lower," "above," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures.

The embodiments of the present invention provide a photocuring three-dimensional molding system for 3D-printing, particularly a vat heating device for heating the photosensitive resin. By directly embedding the heater in the vat and/or in the platform and disposing the heater on an optical path of a light source, the photosensitive resin can be heated directly and uniformly, thereby effectively controlling the reaction temperature of the photosensitive resin to be cured.

<FIG> illustrates a schematic view of a photocuring three-dimensional molding system <NUM> in accordance with some embodiments that do not fall within the scope of the claims. In an embodiment, as shown in <FIG>, the photocuring three-dimensional molding system <NUM> includes a carrier <NUM>, a vat <NUM>, a heater 130a, a scanner <NUM> and a platform <NUM>. In this embodiment, the heater 130a is embedded in the bottom of the vat <NUM>.

First, referring to <FIG>, a vat <NUM> includes a bottom plate <NUM> disposed on the carrier <NUM>, and the vat <NUM> is used to accommodate a photosensitive resin <NUM>. The photosensitive resin <NUM> is polymerized by irradiating with a light source <NUM> to be solidified from a liquid state to a solid state. In some embodiments, the photosensitive resin <NUM> may be acrylates, epoxies, other suitable materials, or a combination thereof, but not limited thereto. The material of the bottom plate <NUM> has a low absorptivity with respect to the wavelength of the light source <NUM> for curing the photosensitive resin <NUM>, such that the light source <NUM> can pass through the bottom plate <NUM> to cure the photosensitive resin <NUM>. In some embodiments, the bottom plate <NUM> may be an inorganic material or a plastic material that is transparent to the light source <NUM>. For example, the transparent inorganic material may be glass, quartz, sapphire, or other suitable materials; the transparent plastic material may be polyoxymethylene (POM), polycarbonate (PC), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), olefin, styrene acrylonitrile (SAN), allyl diglycol carbonate (ADC, also known as CR-<NUM>), polymethylpentene (PMP), or other suitable materials.

Still referring to <FIG>, the heater 130a is embedded in the bottom of the vat <NUM> and on the bottom plate <NUM>. The heater 130a is adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. The heater 130a is a transparent conductive glass heater, and the transparent conductive glass may be, for example, an indium tin oxide (ITO) glass, a fluorine-doped tin oxide (FTO) glass, or other suitable materials. In this embodiment, a surface resistance of the heater 130a is in a range from <NUM> to 1000Ω/□ or <NUM>Ω/sq. The heater 130a is applied with a voltage and then heated as a thermal resistance to provide a high-temperature portion. The temperature of the high-temperature portion may be in a range from <NUM> to <NUM>, for example, from <NUM> to <NUM>. In this embodiment, the temperature rise efficiency per watt of the heater 130a may be in a range from <NUM> to <NUM>. For example, as shown in <FIG>, the temperature rise efficiency per watt of the indium tin oxide (ITO) glass is <NUM>, and the surface temperature of the indium tin oxide (ITO) glass rises steadily as the electric power input increases.

In the above embodiment, an isolation layer 20a may be additionally provided between the heater 130a and the photosensitive resin <NUM> as needed, such that the remaining photosensitive resin <NUM> after completing the molding can be easily removed from the heater 130a for cleaning. The material of the isolation layer 20a has a low absorptivity with respect to the wavelength of the light source <NUM> for curing the photosensitive resin <NUM>, such that the light source <NUM> can pass through the isolation layer 20a to cure the photosensitive resin <NUM>. In some embodiments, the isolation layer 20a may be an inorganic material or a transparent plastic material that is transparent to the light source <NUM>. For example, the transparent inorganic material may be glass, quartz, sapphire, or other suitable materials; the transparent plastic material may be teflon, silicone, parylene, polyoxymethylene (POM), polycarbonate (PC), polystyrene (PS), polypropylene (PP), polyethylene terephthalate (PET), olefin, styrene acrylonitrile (SAN), allyl diglycol carbonate (ADC, also known as CR-<NUM>), polymethylpentene (PMP), or other suitable materials.

In another embodiment, the heater 130a may be a water bath to provide the photosensitive resin <NUM> with a high-temperature portion. The temperature of the high-temperature portion may be in a range from <NUM> to <NUM>, for example, from <NUM> to <NUM>. In this embodiment, the water bath may be a temperature-controlled water bath. Specifically, the temperature-controlled water bath may include a bath body with a transparent bottom and a temperature control device disposed at the transparent bottom to control the temperature of the water bath. In other embodiments, the fluid used for heating may be another transparent fluid other than water. In the embodiment using the water bath, an isolation layer 20a is additionally provided between the heater 130a and the photosensitive resin <NUM> so as to separate the water bath from the photosensitive resin. The material of the isolation layer 20a may be the same as above, and details are not described herein again.

It should be noted that the heater 130a is adjacent to the photosensitive resin <NUM> so that the heater 130a may provide the photosensitive resin <NUM> with a heat source to have a planar and uniform high-temperature portion, and the heat source may directly cover the layer of the photosensitive resin to be cured (i.e., about <NUM>-<NUM> thickness of the photosensitive resin). Thus, the heater 130a can control the temperature of the layer of the photosensitive resin to be cured, and utilize the temperature gradient caused by the heat flux to stably maintain the reaction temperature of the photosensitive resin to be cured. Based on the above, unlike indirect heating with the conventional thermal resistance, the heater 130a provided by the embodiments of the present invention can provide the vat <NUM> with a stable ambient temperature. Therefore, the photocuring three-dimensional molding system <NUM> can be prevented from being affected by the ambient temperature or the climate of different latitudes so as to ensure the quality of the molded product.

In the photocuring molding technique, a print object is constructed by curing the photosensitive resin layer-by-layer through a chemical polymerization. The propagation reaction in the polymerization reaction is a key reaction that determines the polymerization characteristics, and the reaction constant is temperature dependent. Thus, the temperature will affect the polymerization rate, conversion rate and final properties of the material in the photocuring molding technique. That is, in addition to affecting the reaction efficiency of the photocuring process, the temperature also affects the material properties of the cured product.

Still referring to <FIG>, the scanner <NUM> is disposed below the carrier <NUM>. The scanner <NUM> projects the light source <NUM> which passes through the carrier <NUM>, the bottom plate <NUM> of the vat <NUM>, the heater 130a and the platform <NUM> to irradiate and cure the photosensitive resin <NUM> inside the vat <NUM>. That is, the heater 130a is on the optical path of the light source <NUM> for curing the photosensitive resin <NUM>. Furthermore, as shown in <FIG>, the platform <NUM> is disposed above the vat <NUM>, and the platform <NUM> is a lifting platform. The photosensitive resin <NUM> is cured by the light source <NUM> so as to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>.

It should be noted that, in this embodiment, since the first cured curing layer 152a is farthest from the heater 130a, the reaction temperature is lower so that the cured product is softer. In contrast, the closer the curing layers 152b, 152c, 152d and 152e are to the heater 130a, the higher the reaction temperature is, so that the harder the cured product is and the better the reaction efficiency is.

In some embodiments, the light source <NUM> may be an ultraviolet light, for example, ultraviolet light having a wavelength of <NUM>-<NUM>, but not limited thereto. In some embodiments, the heater 130a has a transmittance of <NUM>% to <NUM>% in the spectral range of ultraviolet light. For example, as shown in <FIG>, an indium tin oxide (ITO) glass has a transmittance of <NUM>% to <NUM>% in the spectral range of <NUM> to <NUM>. In some embodiments, the bottom surface of the bottom plate <NUM> and/or the heater 130a may be coated with the anti-reflection coating <NUM> and/or the anti-reflection coating <NUM> so as to reduce the energy loss of the light source <NUM> caused by passing through the bottom plate <NUM> and the heater 130a. In some embodiments, the material of the anti-reflection coating may be tetraethoxysilane (TEOS), diethoxymethylsilane (MDEOS), dimethyldiethoxylsilane (DMDEOS), diphenyldiethoxysilane (PDEOS), vinyltriethoxysilane (VTEOS), aminopropyltriethoxysilane (APTEOS), other suitable materials, or a combination thereof.

It should be noted that since the heater 130a is transparent and ultraviolet light can pass through it, the heater 130a can be disposed on the optical path of the light source <NUM> to directly heat the photosensitive resin, thereby effectively controlling the reaction temperature of the photosensitive resin.

<FIG> illustrate schematic views of a photocuring three-dimensional molding system <NUM> in accordance with other embodiments that do not fall within the scope of the claims. Referring to <FIG>, the photocuring three-dimensional molding system <NUM> is substantially similar to the photocuring three-dimensional molding system <NUM> of the above embodiments, except that the heater 130b of the photocuring three-dimensional molding system <NUM> is embedded in the platform <NUM>.

Specifically, as shown in <FIG>, the heater 130b is embedded in the platform <NUM> and adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. Then, as shown in <FIG>, the photosensitive resin <NUM> is cured by the light source <NUM> to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>.

It should be noted that in this embodiment, as shown in <FIG>, since the first cured curing layer 152a is closest to the heater 130b, the reaction temperature is higher so that the cured product is harder and the reaction efficiency is better. In contrast, the farther the curing layers 152b, 152c, 152d and 152e are from the heater 130b, the lower the reaction temperature is, so that the softer the cured product is.

<FIG> illustrate schematic views of a photocuring three-dimensional molding system <NUM> in accordance with yet other embodiments. Referring to <FIG>, the photocuring three-dimensional molding system <NUM> is substantially similar to the photocuring three-dimensional molding system <NUM> of the above embodiments, except that in the photocuring three-dimensional molding system <NUM>, in addition to embedding the heater 130a in the bottom of the vat <NUM>, the heater 130b is further embedded in the platform <NUM>.

Specifically, as shown in <FIG>, the heater 130a is embedded in the bottom of the vat <NUM> and on the bottom plate <NUM>, and the heater 130b is embedded in the platform <NUM>. Both the heater 130a and the heater 130b are adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. Then, as shown in <FIG>, the photosensitive resin <NUM> is cured by the light source <NUM> to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>.

<FIG> illustrates a schematic view of a photocuring three-dimensional molding system <NUM> in accordance with yet other embodiments. Referring to <FIG>, the photocuring three-dimensional molding system <NUM> is substantially similar to the photocuring three-dimensional molding system <NUM> of the above embodiments, except that in the photocuring three-dimensional molding system <NUM>, in addition to embedding the heater 130a in the bottom of the vat <NUM>, the heater 130c is further embedded in the sidewall of the vat <NUM>.

Specifically, as shown in <FIG>, the heater 130a is embedded in the bottom of the vat <NUM> and on the bottom plate <NUM>, and the heater 130c is embedded in the sidewall of the vat <NUM>. Both the heater 130a and the heater 130c are adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. Then, the photosensitive resin <NUM> is cured by the light source <NUM> to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>. In this embodiment, an isolation layer 20c may be additionally provided between the heater 130c and the photosensitive resin <NUM> as needed, such that the remaining photosensitive resin <NUM> after completing the molding can be easily removed for cleaning. The material of the isolation layer 20c may be the same as above, and details are not described herein again.

<FIG> illustrates a schematic view of a photocuring three-dimensional molding system <NUM> in accordance with yet other embodiments that do not fall within the scope of the claims. Referring to <FIG>, the photocuring three-dimensional molding system <NUM> is substantially similar to the photocuring three-dimensional molding system <NUM> of the above embodiments, except that in the photocuring three-dimensional molding system <NUM>, in addition to embedding the heater 130b in the platform <NUM>, the heater 130c is further embedded in the sidewall of the vat <NUM>.

Specifically, as shown in <FIG>, the heater 130b is embedded in the platform <NUM>, and the heater 130c is embedded in the sidewall of the vat <NUM>. Both the heater 130b and the heater 130c are adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. Then, the photosensitive resin <NUM> is cured by the light source <NUM> to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>. In this embodiment, an isolation layer 20c may be additionally provided between the heater 130c and the photosensitive resin <NUM> as needed, such that the remaining photosensitive resin <NUM> after completing the molding can be easily removed for cleaning. The material of the isolation layer 20c may be the same as above, and details are not described herein again.

<FIG> illustrates a schematic view of a photocuring three-dimensional molding system <NUM> in accordance with yet other embodiments. Referring to <FIG>, the photocuring three-dimensional molding system <NUM> is substantially similar to the photocuring three-dimensional molding system <NUM> of the above embodiments, except that in the photocuring three-dimensional molding system <NUM>, in addition to embedding the heater 130a in the bottom of the vat <NUM> and embedding the heater 130c in the sidewall of the vat <NUM>, the heater 130b is further embedded in the platform <NUM>.

Specifically, as shown in <FIG>, the heater 130a is embedded in the bottom of the vat <NUM> and on the bottom plate <NUM>, the heater 130b is embedded in the platform <NUM>, and the heater 130c is embedded in the sidewall of the vat <NUM>. The heater 130a, the heater 130b and the heater 130c are adjacent to the photosensitive resin <NUM> to heat the photosensitive resin <NUM>. Then, the photosensitive resin <NUM> is cured by the light source <NUM> to form the curing layers 152a, 152b, 152c, 152d, and 152e layer-by-layer below the platform <NUM>.

It should be noted that in the embodiments shown in <FIG>, since the heater 130c is additionally embedded in the sidewall of the vat <NUM>, the photosensitive resin can be heated more stably and uniformly, thereby effectively controlling the reaction temperature of the photosensitive resin.

In summary, the embodiments of the present invention provide a photocuring three-dimensional molding system for 3D-printing, particularly a vat heating device for heating the photosensitive resin. Since the heater of the vat heating device is transparent and light can pass through it, the heater can be directly disposed on the optical path of the light source for curing the photosensitive resin. Furthermore, by embedding the heater in the vat and/or in the platform and making the heater adjacent to the photosensitive resin, the photosensitive resin can be heated stably and uniformly, thereby effectively controlling the reaction temperature of the photosensitive resin to be cured.

Claim 1:
A vat heating device, comprising:
a vat (<NUM>) having a bottom plate (<NUM>) and used to accommodate a photosensitive resin (<NUM>);
a first portion (130a) of a heater disposed on the bottom plate, embedded in a bottom of the vat, and adjacent to the photosensitive resin to heat the photosensitive resin;
a platform (<NUM>) disposed above the vat;
a second portion (130b) of the heater embedded in the platform;
wherein the first portion (130a) of the heater is on an optical path (<NUM>) of a light source (<NUM>) for curing the photosensitive resin:
- wherein the first portion (130a) of the heater is a transparent conductive glass, and
wherein the transparent conductive glass is indium tin oxide (ITO) glass or fluorine-doped tin oxide (FTO) glass, and
- wherein a surface resistance of the first portion (130a) of the heater is <NUM>-1000Ω/sq.