TWI895650B - 3d printer without voxel defects - Google Patents

Abstract

A 3D printer is provided to solve the problem of voxel defects on the surface of the conventional photocuring 3D printing high-resolution models. The 3D printer includes a processing vat, an LCD panel located outside the bottom of the processing vat, an optical film, a printing platform, and a light source module located under the LCD panel. The processing vat has a transparent bottom film. The processing vat is used for accommodating a photocurable material. The display screen of the LCD panel is opposite to the bottom film. The optical film is located between the bottom film and the LCD panel. The printing platform is located above the processing vat and is displaced in the vertical direction. The bottom surface of the printing platform is opposite to the bottom film. The light from the light source module illuminates the LCD panel. The light penetrates the LCD panel, the optical film and the bottom film in sequence, and irradiates the photocurable material, so that the photocurable material is cured and formed on the bottom surface of the printing platform.

Description

Pixel-free 3D printer

The present invention relates to a three-dimensional printing device, and more particularly to a pixel-free three-dimensional printer for printing high-resolution models with smooth surfaces.

3D printing technology is becoming increasingly popular and is widely used in industries such as transportation, architecture, military, industrial design, and dentistry for sample development, customized production, and mold making. The 3D printing process involves horizontally dividing a 3D image into several cross-sections, then sequentially stacking the 2D patterns of each cross-section to form a three-dimensional structure. Several 3D printing technologies can be categorized based on the layering method and materials used. Stereolithography 3D printing utilizes lasers, projectors, or LCD panels to provide light, curing the material layer by layer. This technology is suitable for producing complex precision components and can achieve high resolution and accuracy.

In the aforementioned light-curing 3D printing technology, a 3D printer using a liquid crystal display (LCD) as a patterned light source utilizes the LCD's pixel array to form a 2D image, thereby controlling the passage of light and forming a light-cured area. By sequentially switching the image displayed on the LCD, the 3D model can be cured layer by layer and stacked. Conventional LCD 3D printers are relatively inexpensive and easy to operate, making them suitable for personal or small studio use. However, the pixel array used in the conventional 3D printer is composed of several tiny blocks. Due to the diffraction properties of light, when light passes through the boundaries of pixel blocks, it produces a pattern of bright and dark patterns. This results in insufficient illumination where light curing should occur, preventing complete curing. Observing the finished model surface with a high-resolution electron microscope reveals uneven pixel marks. Even if LCD image resolution is increased to 4K or 8K, pixel mark defects on 3D models cannot be inherently eliminated.

In view of this, conventional 3D printers still need improvement.

To solve the above-mentioned problem, the purpose of the present invention is to provide a pixel mark-free 3D printer that can eliminate pixel mark defects.

A second objective of the present invention is to provide a pixel-free 3D printer that can improve printing resolution and be used to print ultra-smooth surfaces for rapid manufacturing of optical components.

Throughout this disclosure, directional terms or similar terms, such as "upper (top)", "lower (bottom)", "inner", "outer", "side", etc., are primarily used with reference to the directions in the accompanying drawings. These directional terms or similar terms are intended solely to facilitate the description and understanding of the various embodiments of the present invention and are not intended to limit the present invention.

The use of the quantifiers "a" or "an" in the elements and components described throughout this invention is merely for convenience and to provide a general understanding of the scope of the invention. They should be interpreted in this invention to include one or at least one, and the singular concept also includes the plural, unless it is obvious that it means otherwise.

Throughout this invention, similar terms such as "combination," "assembly," or "assembly" primarily encompass connection types that allow for separation without damaging the components, or connection types that render the components inseparable. Those skilled in the art will be able to select the appropriate type based on the materials of the components to be connected or the assembly requirements.

The present invention's pixel-mark-free 3D printer comprises: a working tank having an opening and a transparent base film located at the bottom of the working tank, the working tank being used to accommodate a light-curable material; a liquid crystal panel located outside the bottom of the working tank, with the display screen of the liquid crystal panel facing the base film; and an optical film located between the base film and the liquid crystal panel. The optical film has a controllable haze value and is switched to an atomized state. The atomized optical film is used to guide light paths in different directions. The system converts alternating light intensities into uniform illumination. A printing platform is located above the working tank, with its bottom surface facing the base film. The printing platform moves vertically and enters and exits the working tank through the opening. A light source module is located below the liquid crystal panel. Light from the light source module illuminates the liquid crystal panel, sequentially penetrating the liquid crystal panel, the optical film, and the base film, irradiating the photocurable material in the working tank, causing it to cure and form a layer on the bottom surface of the printing platform.

Accordingly, the pixel mark-free 3D printer of the present invention, by laminating the optical film to the image output port of the LCD panel, can modulate the atomized light through the optical film to eliminate dark image lines formed at the pixel boundaries of the LCD panel, allowing light to evenly illuminate the photocurable material. This prevents pixel mark defects on the surface of the printed product, improving 3D printing resolution and producing products with smoother surfaces.

The optical film comprises two transparent, conductive substrates and a liquid crystal material positioned between them. An electric field applied between the substrates switches the optical film's haze state and adjusts the haze value. The magnitude of the electric field between the two substrates alters the alignment of the liquid crystal molecules, causing light to be randomly reflected by the chaotically arranged liquid crystal molecules, thus varying the luminous flux and illumination uniformity.

The light is scattered by the atomized optical film and emitted in different directions. This allows for a uniform distribution of light intensity, effectively eliminating pixel marks on printed products.

The liquid crystal panel has a pixel array formed by liquid crystal molecules. The transmittance and shielding states of each pixel in the pixel array form the printed image. Increasing the pixel density of the liquid crystal panel can improve image resolution and thus enhance printing precision.

The light source module includes several LEDs, each emitting light at a wavelength of 200 to 410 nanometers. This allows the module to emit ultraviolet light to trigger the curing reaction of the photocurable material, thereby improving photocuring efficiency.

1: Work Slot

11: Base film

2: LCD panel

3: Optical Films

4: Printing Platform

5: Light source module

P:Platform

H: Opening

[Figure 1] A perspective view of a preferred embodiment of the present invention.

[Figure 2] A cross-sectional view of a preferred embodiment of the present invention.

To make the above and other objects, features, and advantages of the present invention more clearly understood, the following provides a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. Furthermore, elements marked with the same symbols in different drawings are considered identical and their descriptions will be omitted.

Please refer to Figures 1 and 2, which illustrate a preferred embodiment of the pixel-free 3D printer of the present invention. The printer comprises a working tank 1, a liquid crystal panel 2, an optical film 3, a printing platform 4, and a light source module 5. The liquid crystal panel 2 is located on the bottom outer side of the working tank 1, the optical film 3 is located between the working tank 1 and the liquid crystal panel 2, the printing platform 4 is movable vertically above the working tank 1, and the light source module 5 is located below the working tank 1, the liquid crystal panel 2, and the optical film 3.

The working tank 1 is used to hold a light-curing material, such as a liquid photosensitive resin. The working tank 1 can be fastened to a carrier P of the 3D printer, with the opening of the working tank 1 facing upward. The light-curing material can be poured from the opening into the internal storage space of the working tank 1. The working tank 1 has a base film 11 located at the bottom of the working tank 1, opposite the opening. The base film 11 can be made of fluorinated ethylene propylene (FEP) or other transparent film materials. Furthermore, the carrier P has an opening H. When the working tank 1 is fixed to the carrier P, the unfolded position of the base film 11 can correspond to the opening H. Light can enter the opening H from below the carrier P, penetrate the base film 11, and enter the internal storage space of the working tank 1, causing the light-curing material to cure.

The liquid crystal panel 2 comprises a pixel array formed by a large number of liquid crystal molecules. By switching the electric field acting on each pixel to control its light-transmitting and light-blocking states, the backlight illuminates the liquid crystal panel 2, displaying an image composed of the varying brightness of each pixel. The liquid crystal panel 2 is positioned below the working tank 1 and adjacent to the base film 11, with the display facing the base film 11. The image displayed by the liquid crystal panel 2 is projected onto the base film 11. Furthermore, the liquid crystal panel 2 can be coupled to the carrier P. In this embodiment, the liquid crystal panel 2 is embedded within the opening H of the carrier P. However, the present invention is not limited to the method of coupling the liquid crystal panel 2 to the carrier P.

The optical film 3 is a thin film device that can adjust the haze value (Haze) and light transmittance. For example, the optical film 3 can include two transparent and conductive substrates and a liquid crystal material located between the two substrates. The potential difference between the two substrates can be 0-60 volts. The electric field between the two substrates can be controlled to change the arrangement of the liquid crystal molecules. When the liquid crystal molecules are neatly arranged, light can pass directly through the optical film 3. Film 3 is in a transparent state with high transmittance. When the liquid crystal molecules are irregularly and chaotically arranged, light passing through the optical film 3 is disrupted by the randomly distributed liquid crystal molecules, causing scattering. The scattered light travels in different directions, causing the optical film 3 to enter an atomized state with increased haze and low transmittance. Furthermore, by controlling the magnitude of the electric field acting on the liquid crystal molecules, the degree of disorder can be varied, thereby adjusting the haze and light transmittance of the optical film 3. The thickness of the optical film 3 is preferably between 0.25 mm and 0.35 mm. The optimal transmittance of the optical film 3 in the transparent state is 90%. The haze value in the atomized state can be gradually increased from 3% to 90%.

The optical film 3 is positioned between the base film 11 of the working tank 1 and the liquid crystal panel 2. This allows the image light output by the liquid crystal panel 2, which selectively blocks light from the pixel array, to pass through the optical film 3 for atomization before being projected onto the base film 11. The optical film 3 redirects the light path, transforming the alternating high and low intensity at the pixel boundaries into a smooth and stable state. This allows the photocurable material to receive uniform illumination during the curing process, rather than creating alternating bright and dark patterns. This effectively eliminates pixel marks in the finished photocured product.

The printing platform 4 is positioned above the working tank 1, with its bottom surface preferably parallel and aligned with the base film 11. The printing platform 4 can be displaced vertically, allowing it to enter and exit the opening of the working tank 1 and immerse itself in the photocurable material. At its lowest position, the printing platform 4's bottom surface contacts the base film 11. As the LCD panel 2 displays the cross-section of a 3D image layer by layer, the printing platform 4 simultaneously rises, causing the exposed photocurable material to harden layer by layer and accumulate on the bottom surface of the printing platform 4, forming an inverted 3D printed model. The printing platform 4 can be constructed of aluminum alloy, which offers durability, light weight, and a smooth surface, making it suitable for repeated lifting and 3D printing.

The light source module 5 emits light that illuminates the LCD panel 2, serving as its backlight. The light source module 5 may include several light-emitting diodes (LEDs), each emitting light in the wavelength range of 200 nm to 410 nm, which is within the ultraviolet (UV) and near-UV bands. Light in this wavelength range can trigger a curing reaction in the photocurable material. The light source module 5 may also include components such as a light guide plate, a diffuser, a lampshade, and a backplane to guide the light, control the illuminated area, and improve illumination uniformity.

The printing process of the preferred embodiment of the pixel-free 3D printer of the present invention is as follows: first, the light-curing material is poured into the storage space of the working tank 1, and then the printing platform 4 is lowered to immerse it in the light-curing material, and the bottom surface of the printing platform 4 is parallel to the base film 11 and separated by a layer of thickness. When printing begins, the LCD panel 2 displays an image of the bottom cross-section of the model to be processed, and the light source module 5 irradiates the liquid with ultraviolet light from bottom to top. The image output by the LCD panel 2 is uniformly transmitted through the optical film 3 to eliminate dark lines, and then passes through the bottom mold 11, allowing the photocurable material exposed to the image area to be formed on the printing platform 4. Next, the LCD panel 2 and the printing platform 4 switch to the next cross-sectional image and rise one layer height at the same time interval, respectively, so that the bottom surface of the printing platform 4 gradually stacks the three-dimensional model to be worked.

In summary, the pixel-mark-free 3D printer of the present invention, by attaching an optical film to the image output port of the LCD panel, can eliminate dark lines formed at the pixel boundaries of the LCD panel through the atomization of light by the optical film, allowing light to evenly illuminate the photocurable material. This prevents pixel mark defects on the surface of the printed product, improving 3D printing resolution and producing products with smoother surfaces.

Although the present invention has been disclosed using the preferred embodiments described above, they are not intended to limit the present invention. Any person skilled in the art may make various changes and modifications to the above embodiments without departing from the spirit and scope of the present invention. These changes and modifications are still within the technical scope protected by the present invention. Therefore, the scope of protection of the present invention shall include all changes within the meaning and equivalent scope of the appended patent applications.

1: Working tank 11: Base film 2: LCD panel 3: Optical film 4: Printing platform 5: Light source module P: Carrier H: Opening

Claims (5)

A pixel-mark-free three-dimensional printer comprises: a working tank having an opening and a transparent base film located at the bottom of the working tank, the working tank being used to accommodate a light-curable material; a liquid crystal panel located on the outer side of the bottom of the working tank, with the display screen of the liquid crystal panel facing the base film; an optical film located between the base film and the liquid crystal panel, with a haze value of the optical film being adjusted and switched to an atomized state, the optical film in the atomized state being used to guide the light path in different directions, converting alternating high and low light intensities into uniform illumination; a printing platform located above the working tank, with the bottom surface of the printing platform facing the base film, the printing platform being displaced in a vertical direction and entering and exiting the working tank through the opening; and A light source module is located below the liquid crystal panel. The light from the light source module illuminates the liquid crystal panel. The light penetrates the liquid crystal panel, the optical film and the base film in sequence and illuminates the light-curing material in the working tank. The light-curing material is cured and formed on the bottom surface of the printing platform. As for the pixel-mark-free three-dimensional printer of claim 1, the optical film has two transparent and conductive substrates and a liquid crystal material located between the two substrates, and the electric field applied between the two substrates switches the atomization state of the optical film and adjusts the haze value. As for the pixel mark-free three-dimensional printer of claim 1, the light is scattered by the optical film in the atomized state and emitted in different directions. As for the pixel mark-free three-dimensional printer of claim 1, the liquid crystal panel has a pixel array formed by liquid crystal molecules, and the light-transmitting and light-shielding states of each pixel in the pixel array are arranged to form a printed image. As for the pixel mark-free three-dimensional printer of claim 1, wherein the light source module has a plurality of light-emitting diodes, and the light-emitting wavelength of each light-emitting diode is 200 nanometers to 410 nanometers.