KR20230174793A - Image processing method for high-precision ceramic 3d printing and high-precision ceramic 3d printing method using the same - Google Patents

Abstract

The present invention relates to an image processing method for high-precision ceramic 3D printing and a high-precision ceramic 3D printing method using the same. According to one aspect of the present invention, a 3D image for 3D printing a 3D structure is cut into a cross section perpendicular to the stacking direction. A 2D slice image generating step of generating a 2D slice image by slicing at intervals corresponding to the stack thickness, a primary correction target pixel selection step of selecting a pixel corresponding to the border of the 2D slice image as a primary correction target pixel, A pixel additional correction condition determination step of determining whether a pixel to be corrected firstly meets a pixel additional correction condition; additionally correcting the brightness value of the pixel to be firstly corrected corresponding to the pixel additional correction condition; and adding the pixel. It includes a pixel correction step of first correcting the brightness values of the remaining primary correction target pixels that do not meet the correction conditions.

Description

Image processing method for high-precision ceramic 3D printing and high-precision ceramic 3D printing method using the same {IMAGE PROCESSING METHOD FOR HIGH-PRECISION CERAMIC 3D PRINTING AND HIGH-PRECISION CERAMIC 3D PRINTING METHOD USING THE SAME}

The present invention relates to an image processing method for high-precision ceramic 3D printing and a high-precision ceramic 3D printing method using the same. More specifically, an image processing method for high-precision ceramic 3D printing that improves the precision of photocuring 3D printing. and a high-precision ceramic 3D printing method using the same.

3D printing is a machine that molds 3D objects based on 3D images, and has recently been actively used in various industrial fields. In particular, research is actively underway to apply 3D printing to the manufacture of products that require customized manufacturing, such as artificial teeth.

Artificial teeth replace natural teeth in the oral cavity and play an important role in mastication, so they must have the same excellent durability as natural teeth, and must be manufactured in the same shape as existing natural teeth to minimize the feeling of heterogeneity in the oral cavity. , high precision molding is required.

In addition, recently, the demand for artificial teeth made of ceramic materials that have aesthetics similar to actual natural teeth and have excellent biostability and durability has been increasing. However, artificial teeth made of ceramic raw materials must undergo sintering after molding, and sintering shrinkage is induced during the sintering process, and microscopic defects generated during the molding process may appear as cracks after sintering, so high precision control during the molding process. is required.

Meanwhile, among 3D printing methods, photocuring 3D printing, which allows for high-precision molding, is being widely studied as an artificial tooth forming technology. Artificial teeth made of ceramic materials through photocuring 3D printing are formed by laminating a raw material mixed with photocurable resin and ceramic raw materials. This is done by curing to produce the primary molding, and then sintering it to complete the secondary molding made of pure ceramic material.

On the other hand, if the photocurable resin is not sufficiently cured, the shape of the primary molding may collapse and cracks may occur during the sintering process. Accordingly, it is required to cure the raw material with a sufficient amount of light. However, as sufficient light is irradiated, a problem may occur in which the size of the primary molding becomes larger than the size of the initially designed molding.

Therefore, there is a need for the development of 3D printing technology that can suppress the occurrence of cracks during the sintering process and at the same time accurately print the size of the primary molded product at the intended size.

Meanwhile, the above-described background technology is technical information that the inventor possessed for deriving the present invention or acquired in the process of deriving the present invention, and cannot necessarily be said to be known technology disclosed to the general public before filing the application for the present invention. .

Korean Patent No. 10-2149934 (2020.08.25)

One embodiment of the present invention provides an image processing method for high-precision ceramic 3D printing that can improve the molding precision of the molded product even when the molded product is made of ceramic material with a sufficient amount of light, and a high-precision ceramic 3D printing method using the same. There is a purpose to it.

In addition, an embodiment of the present invention is an image processing method for high-precision ceramic 3D printing that can minimize cracking problems that may occur during the sintering process after manufacturing a molded product of ceramic material, and a high-precision ceramic 3D printing method using the same. The purpose is to provide.

As a technical means for achieving the above-described technical problem, according to one aspect of the present invention, a 3D image for 3D printing a 3D structure is sliced in a cross section perpendicular to the stacking direction at intervals corresponding to the stack thickness to generate a 2D slice image. A 2D slice image generation step, a primary correction target pixel selection step of selecting a pixel corresponding to the border of the 2D slice image as a primary correction target pixel, and whether the pixel additional correction conditions are met for the primary correction target pixel. A pixel additional correction condition determination step for determining and additionally correcting the brightness value of the primary correction target pixel corresponding to the pixel additional correction condition, and the brightness value of the remaining primary correction target pixel that does not correspond to the pixel additional correction condition. It includes a pixel correction step of first correction.

According to another aspect of the present invention, the step of selecting the primary correction target pixel includes selecting the outermost and innermost border pixels of the 2D slice image as the primary correction target pixel, and the pixel correction step It includes setting the brightness value of the primary correction target pixel to be the first correction as a first brightness value, and the first brightness value may be a brightness value of less than 20% of the brightness value of the pixel before correction. .

According to another aspect of the present invention, the pixel additional correction condition determining step includes determining whether the primary correction target pixel is a 2x2, 3x3, or 4x4 pixel, and the pixel correction step includes determining whether the pixel to be corrected is a 2x2, 3x3, or 4x4 pixel. It may include setting the brightness value of the 4x4 pixel to a second brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value.

According to another aspect of the present invention, the step of determining the pixel additional correction conditions includes determining whether three or more other primary correction target pixels exist adjacent to one of the primary correction target pixels. It includes a step of determining, wherein the pixel correction step is performed when there are more than 3 pixels of other primary correction target pixels adjacent to the one primary correction target pixel. It may include setting the brightness value of the pixel to a third brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value.

According to another aspect of the present invention, the step of determining pixel additional correction conditions includes determining whether the primary correction target pixels are arranged horizontally or vertically in a continuous line, and the pixel correction step includes: It may include setting the brightness value of the first correction target pixel, which is arranged horizontally or vertically in only one row, to a fourth brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value. .

As a technical means for achieving the above-mentioned technical problem, according to another aspect of the present invention, a layer providing step of providing a raw material layer to a plate for 3D printing a 3D structure, and a layer photocuring step of irradiating the layer with light. , the light is irradiated based on a corrected 2D slice image generated by slicing the 3D image of the 3D structure at intervals corresponding to the stacking thickness, as a plane perpendicular to the stacking direction, and correcting the 2D slice image according to correction conditions. , the corrected 2D slice image selects a pixel corresponding to the border of the 2D slice image as a primary correction target pixel, determines whether the primary correction target pixel meets a pixel additional correction condition, and Partially irradiating light to the layer created by additionally correcting the brightness value of the primary correction target pixel corresponding to additional correction and performing primary correction on the remaining primary correction target pixels that do not correspond to the pixel additional correction conditions. It includes a layer photocuring step and a lamination step of repeating the layer providing step and the cross-section forming step until the 3D structure is manufactured.

According to another aspect of the present invention, the layer photocuring step is to change the brightness value of the primary correction target pixel to a first brightness value that is less than 20% of the brightness value applied to the pixel before correction. , and irradiating light with a first amount of light to an area corresponding to the primary correction target pixel set to the first brightness value, wherein the first amount of light is 20 times the amount of light applied to the pixel before correction. The amount of light may be less than %.

According to another aspect of the present invention, the layer photocuring step determines whether the primary correction target pixel is a 2x2, 3x3, or 4x4 pixel, and determines the brightness value of the 2x2, 3x3, or 4x4 pixel. is set to a second brightness value that is smaller than the brightness value of the pixel before correction and greater than the first brightness value, and is applied to the pixel before correction in an area corresponding to the 2x2, 3x3, or 4x4 pixel set to the second brightness value. It may include irradiating light with a second light quantity that is smaller than the applied light quantity and greater than the first light quantity.

According to another aspect of the present invention, the layer photocuring step determines whether three or more other primary correction target pixels exist adjacent to one of the primary correction target pixels. And, when there are three or more other primary correction target pixels adjacent to the one primary correction target pixel, the brightness value of the one primary correction target pixel is equal to the brightness of the pixel before correction. A third brightness value is set to a third brightness value that is smaller than the value and larger than the first brightness value, and is smaller than the amount of light applied to the pixel before correction in the area corresponding to the one primary correction target pixel set to the third brightness value. , It may include the step of irradiating light with a third light quantity greater than the first light quantity.

According to another aspect of the present invention, the layer photocuring step determines whether the primary correction target pixels are arranged horizontally or vertically in a continuous line only, and the pixels are arranged horizontally or vertically in a continuous line only in one line. The brightness value of the corrected pixel is set to a fourth brightness value that is smaller than the brightness value of the pixel before correction and greater than the first brightness value, and the pixels that are set to the fourth brightness value are arranged horizontally or vertically in only one line. It may include irradiating light to the area corresponding to a fourth light quantity that is smaller than the light quantity applied to the pixel before correction and greater than the first light quantity.

According to one of the means for solving the problems of the present invention described above, the image processing method for high-precision ceramic 3D printing and the high-precision ceramic 3D printing method using the same include the step of first correcting the border pixels, so that the input 3D When a sufficient amount of light is irradiated to the structure, the problem that the size of the primary molded product differs from the design size of the 3D image for 3D printing due to over-curing is solved, so the primary molded product can be molded with a sufficient amount of light and at the same time, the precision of the primary molded product is maintained. There is an advantage to improving .

In addition, according to one of the means for solving the problem of the present invention, the image processing method for high-precision ceramic 3D printing and the high-precision ceramic 3D printing method using the same include a pixel additional correction condition determination step and a pixel correction step, so that the image This prevents parts of the thin structure from being deleted during the processing process, and solves the problem of reduced forming precision.

The effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

1 is a flowchart of an image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention.
Figures 2 (a) to (d) are diagrams for explaining an image processing method for high-precision ceramic 3D printing.
Figures 3 (a) to (d) are diagrams for explaining an example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.
Figures 4 (a) to (d) are diagrams for explaining another example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.
Figures 5 (a) to (d) are diagrams to explain another example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.
Figures 6 (a) and (b) are 2D slice images before and after image processing is completed according to the image processing method for high-precision ceramic 3D printing.
Figure 7 is a flowchart of a high-precision ceramic 3D printing method according to an embodiment of the present invention.

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are given similar reference numerals throughout the specification.

Throughout the specification, when a part is said to be “connected” to another part, this means not only the case where it is “directly connected” but also the case where it is “indirectly connected” with another member or element in between. Includes. Additionally, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

Hereinafter, the present invention will be described in detail with reference to the attached drawings.

1 is a flowchart of an image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention.

Referring to FIG. 1, the image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention first divides a 3D image for 3D printing a 3D structure into a cross section perpendicular to the stacking direction at intervals corresponding to the stack thickness. Create a 2D slice image by slicing (S11).

A 3D image is a digital 3D image that provides information about the dimensions and shape of a 3D structure in order to 3D print the 3D structure. It is created by scanning the structure to be manufactured with a 3D scanner, or is created using 3D software such as CAD (Computer Aided Design). It can be created by directly designing it through a rendering program.

A 2D slice image refers to a cross-sectional image of a 3D structure in the stacking direction, and the 2D slice image is created by slicing the 3D image of the 3D structure into a cross section perpendicular to the stacking direction.

In this case, slicing may be performed at predetermined intervals. For example, a 2D slice image can be created by slicing a 3D image in a cross section perpendicular to the stacking direction at intervals of 1 μm or more and 100 μm or less.

The above-described slicing is done through slicing software, and the slicing software can be installed as a separate module in the above-described 3D rendering program. As described above, since the 2D slice image is created by slicing the 3D image at predetermined intervals, a 3D image of the same shape and size as the 3D structure can be generated by stacking the 2D slice images sequentially according to the slicing order.

When a 2D slice image is created by slicing the 3D image, the pixel corresponding to the border of the 2D slice image is selected as the primary pixel to be corrected (S12).

The primary correction target pixel selection (S12) step includes selecting the outermost and innermost border pixels of the 2D slice image as the primary correction target pixels. The selected primary correction target pixels may be 1 to 3 pixels from the outermost and innermost sides of the 2D slice image depending on the resolution of the light source. That is, the outermost border pixels of the 2D slice image correspond to the first to third outermost pixels on the 2D slice image, and the innermost pixels of the 2D slice image correspond to the first to third innermost pixels of the 2D slice image.

When the primary correction target pixel is selected, a pixel additional correction condition determination (S13) is performed to determine whether the pixel to be corrected first correction meets the pixel additional correction condition.

The step of determining pixel additional correction conditions (S13) determines whether to perform additional correction for the pixels subject to primary correction with respect to the outermost and innermost border pixels of the 2D slice image selected through the selection of primary correction target pixels (S12). This is the stage where you decide whether to do it or not.

Afterwards, pixel correction (S14) is performed. The pixel correction (S14) step is performed by additionally correcting the pixel subject to primary correction if it meets the pixel additional correction conditions, and performing primary correction of the pixel subject to primary correction if it does not meet the pixel additional correction condition. You can.

To describe in detail how to perform the pixel additional correction condition determination (S13) step and the pixel correction (S14) step, refer to FIGS. 2 to 5 together.

Figures 2 (a) to (d) are diagrams for explaining an image processing method for high-precision ceramic 3D printing.

Figure 2(a) illustrates an example of a 2D slice image. First, in the first correction target pixel selection (S12) step, the outermost and innermost border pixels of the 2D slice image may be selected. In the case of Figure 2(b), this is an example in which one pixel at the outermost and innermost side of the 2D slice image is selected as the primary correction target pixel.

Thereafter, in the pixel additional correction condition determination step (S13), it is determined whether the selected primary correction target pixel satisfies the pixel additional correction condition and it is decided whether to perform primary correction or additional correction.

Next, in the pixel correction (S14) step, additional correction is performed on pixels subject to primary correction that meet the pixel additional correction conditions, and primary correction is performed on pixels subject to primary correction that do not meet the pixel additional correction conditions. do. If all pixels subject to primary correction do not meet the pixel additional correction conditions, all pixels subject to primary correction are subjected to primary correction. In other words, the brightness value of the primary correction target pixel that does not meet the pixel additional correction determination conditions is corrected to a first brightness value that is less than 20% of the brightness value of the pixel before correction (or a normal pixel that is not a primary correction target pixel). . Figure 2(c) shows an example in which the brightness values of all primary correction target pixels are first corrected to the first brightness value. That is, all primary correction target pixels that are primarily corrected to the first brightness value because they do not meet the pixel additional correction determination conditions are shown as solid lines.

Afterwards, actual cross-section hardening is performed based on the 2D slice image on which the pixel correction (S14) step has been performed. Figure 2(d) shows a cross-section of a 3D structure formed by photocuring based on a 2D slice image on which a pixel correction (S14) step was performed.

First, a sufficient amount of light is irradiated to pixels (white pixels) that are not primary correction target pixels. Here, “sufficient light quantity” refers to the light quantity set by the user for 3D printing, and refers to the light quantity used to harden pixels before correction (or normal pixels that are not primary correction target pixels) on a 2D slice image. Accordingly, overhardening occurs in the area corresponding to the pixel that is not the primary correction target pixel, and the hardened area extends to the surrounding area of the pixel that is not the primary correction target pixel.

On the other hand, the cross-sectional hardening of the primary correction target pixel, whose brightness value has been first corrected because it does not meet the pixel additional correction judgment conditions, is the amount of light applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel). It may be performed in such a way that a first amount of light less than 20% is irradiated. At this time, the first light quantity of less than 20% irradiated to the primary correction target pixel means a very low light quantity compared to the sufficient light quantity of less than 20% of the sufficient light quantity, assuming that the sufficient light quantity is 100% of the sufficient light quantity. Accordingly, the first correction target pixel is cured with a relatively very low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and overcuring may not occur.

A sufficient amount of light is irradiated to pixels that are not primary correction target pixels, and a relatively very low amount of light compared to the sufficient light amount is irradiated to pixels to be primarily corrected. Accordingly, over-hardening occurs in the area corresponding to a pixel that is not a primary correction target pixel, and over-hardening does not occur in an area corresponding to a primary correction target pixel. Therefore, as finally shown in (d) of FIG. 2, a cross-section with the same shape as the initially intended slice image ((a) of FIG. 2) can be formed. Figure 2(d) shows a cross-section of a 3D structure formed by photocuring with a sufficient amount of light.

Figures 3 (a) to (d) are diagrams for explaining an example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.

Figure 3(a) illustrates an example of a 2D slice image. First, in the first correction target pixel selection (S12) step, the outermost and innermost border pixels of the 2D slice image are selected. The selected primary correction target pixel is shown in (b) of FIG. 3.

Thereafter, in the pixel additional correction condition determination step (S13), it is determined whether the selected primary correction target pixel satisfies the pixel additional correction condition and it is decided whether to perform primary correction or additional correction.

Specifically, it is determined whether the primary correction target pixels are arranged in a 2x2, 3x3, or 4x4 matrix. For convenience of explanation, the case of determining whether the pixels subject to primary correction are arranged in a 2x2, 3x3, or 4x4 matrix is defined as the “first additional correction judgment condition.” In this case, a mask corresponding to a 2x2, 3x3, or 4x4 pixel size can be applied to the slicing image, and it can be determined whether the primary correction target pixel is filled in the 2x2, 3x3, or 4x4 mask.

Next, in the pixel correction (S14) step, primary correction is performed on pixels subject to primary correction that do not meet the first additional correction determination condition. In other words, the brightness value of the primary correction target pixel that does not meet the first additional correction judgment condition is first adjusted to a first brightness value that is less than 20% of the brightness value of the pixel before correction (or a normal pixel that is not a primary correction target pixel). Correct.

Meanwhile, additional correction is performed on the primary correction target pixel that satisfies the first additional correction determination condition. In other words, the brightness value of the first correction target pixel that satisfies the first additional correction judgment condition is lower than the brightness value of the pixel before correction (or a normal pixel that is not the first correction target pixel) and a second brightness that is greater than the first brightness value. Correct with value. For example, when the pixels subject to primary correction are arranged in a 2x2 arrangement, the brightness value of the pixels in the 2x2 array may be corrected to a second brightness value of 20% to 100% of the brightness value of the pixel before correction. In Figure 3(c), the brightness values of the primary correction target pixels arranged in a 2x2 matrix that satisfy the first additional correction judgment condition are additionally corrected to the second brightness value, and the remaining first correction target pixels that do not satisfy the additional correction condition are additionally corrected. An example of first correcting the brightness value of a pixel to the first brightness value is shown. That is, pixels that were first corrected to the first brightness value because they did not meet the first additional correction conditions are shown in solid lines, and pixels that were additionally corrected to the second brightness value by meeting the first additional correction judgment conditions are shown in dark gray. , pixels that are not subject to primary and additional correction are shown in white.

Afterwards, actual cross-section hardening is performed based on the 2D slice image on which the pixel correction (S14) step has been performed. Figure 3(d) shows a cross-section of a 3D structure formed by photocuring based on a 2D slice image on which a pixel correction (S14) step was performed.

First, a sufficient amount of light is irradiated to pixels (white pixels) that are not primary correction target pixels. Accordingly, overhardening occurs in the area corresponding to the pixel that is not the primary correction target pixel, and the hardened area extends to the surrounding area of the pixel that is not the primary correction target pixel.

Meanwhile, the cross-sectional hardening of the primary correction target pixel (solid line pixel) whose brightness value was first corrected because it did not meet the pixel additional correction judgment conditions is applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel). It may be performed in a way that light is irradiated with a first light amount that is less than 20% of the applied light amount. Accordingly, the first correction target pixel is cured with a relatively very low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and overcuring may not occur.

Finally, the cross-sectional hardening of the primary correction target pixel, whose brightness value has been additionally corrected by satisfying the first additional correction judgment condition, is less than the amount of light applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel) , it can be performed in a way that light is irradiated with a second light quantity that is greater than the first light quantity. For example, cross-section hardening of the primary correction target pixel (dark gray pixel) that satisfies the first additional correction judgment condition and the brightness value of the pixel is corrected to a second brightness value of 20% to 100% of the brightness value of the pixel before correction. may be performed in such a way that a second light amount of 20% or more but less than 100% of the light amount applied to the pixel before correction is irradiated. At this time, the second light quantity of 20% to less than 100% irradiated to the primary correction target pixel is a lower light quantity compared to the sufficient light quantity of 20% to less than 100% of the sufficient light quantity, assuming that the sufficient light quantity is 100% of the light quantity. means. Accordingly, the primary correction target pixel, whose brightness value of the pixel has been additionally corrected by satisfying the first additional correction judgment condition, is cured with a relatively low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and over-curing does not occur. It may not be possible.

A sufficient amount of light is irradiated to pixels that are not primary correction target pixels, and a relatively very low amount of light compared to the sufficient light amount is irradiated to the primary correction target pixels that have been primarily corrected, and the additionally corrected primary correction target pixels A relatively low amount of light is irradiated compared to the sufficient amount of light. Accordingly, overhardening occurs in the area corresponding to the pixel that is not the primary correction target pixel, and overhardening occurs in the area corresponding to the primary correction target pixel and the area corresponding to the additionally corrected primary correction target pixel. It doesn't work. Therefore, as finally shown in (d) of FIG. 3, a cross-section with the same shape as the initially intended slice image ((a) of FIG. 3) can be formed. Figure 3(d) shows a cross-section of a 3D structure formed by actual photocuring.

Figures 4 (a) to (d) are diagrams for explaining another example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.

Figure 4(a) illustrates another example of a 2D slice image. First, in the first correction target selection (S12) step, the outermost and innermost border pixels of the 2D slice image are selected. The selected primary correction target pixel is shown in (b) of FIG. 4.

Thereafter, in the pixel additional correction condition determination step (S13), it is determined whether the selected primary correction target pixel satisfies the pixel additional correction condition and it is decided whether to perform primary correction or additional correction.

At this time, the first correction target pixel determines whether there is a pixel that satisfies the first additional correction determination condition, as in FIG. 3. Next, a second additional correction judgment condition is determined for pixels subject to primary correction except for pixels that satisfy the first additional correction judgment condition. The second additional correction judgment condition determines whether there are at least 3 pixels of other primary correction target pixels adjacent to one of the primary correction target pixels that do not satisfy the first additional correction judgment condition. It means judging. For example, pixels located at 'top, bottom, right', 'top, bottom, left', 'top, left, right', and 'left, right, bottom' based on one primary correction target pixel. The second additional correction determination condition may be determined based on whether all pixels are composed of different primary correction target pixels. In this case, it can be determined whether the second additional correction determination condition is met by applying a mask having the shapes of 'ㅏ', 'ㅓ', 'ㅗ', and 'ㅜ'. Referring to (b) of FIG. 4, when a mask having the shape of 'ㅓ' is applied to the slicing image, the primary correction target pixel 100 is adjacent to the primary correction target pixel 100 and an 'image' is formed adjacent to the primary correction target pixel 100. Since all pixels located in the 'bottom, left' are comprised of pixels subject to primary correction, the second additional correction judgment condition step is satisfied. In addition, the primary correction target pixel 200 is a pixel adjacent to the primary correction target pixel 200 and located 'up, down, and right' when a mask having the shape of 'ㅏ' is applied to the slicing image. Since they all consist of primary correction target pixels, the second additional correction judgment condition step is satisfied.

Next, in the pixel correction (S14) step, the first correction target pixel that satisfies the first additional correction judgment condition has its brightness value changed to the brightness value of the pixel before correction (or a normal pixel that is not the first correction target pixel) as shown in FIG. It is corrected to a second brightness value that is smaller and larger than the first brightness value. In addition, excluding pixels that satisfy the first additional correction judgment condition, the brightness value of the primary correction target pixel that satisfies the second additional correction judgment condition is equal to the brightness value of the pixel before correction (or a normal pixel that is not the first correction target pixel). It is corrected to a third brightness value that is smaller and larger than the first brightness value. For example, when there are three or more other primary correction target pixels adjacent to one primary correction target pixel, the brightness value of any one primary correction target pixel is equal to the brightness of the pixel before correction. It can be corrected to a third brightness value of 50% or more and less than 100% of the value. Except for pixels that satisfy the first and second additional correction determination conditions, the remaining pixels subject to primary correction that do not meet the additional correction conditions may be subjected to primary correction. In Figure 4(c), the brightness value of the pixel that satisfies the first additional correction judgment condition is additionally corrected to the second brightness value, and the brightness value of the pixel that satisfies the second additional correction judgment condition is additionally corrected to the third brightness value. , an example is shown in which the brightness values of the remaining primary correction target pixels that do not meet the first and second additional correction conditions are first corrected to the first brightness value. That is, pixels that were first corrected to the first brightness value because they did not meet the first and second additional correction conditions are shown in solid lines, and pixels that were additionally corrected to the second brightness value by meeting the first additional correction judgment conditions are shown in dark gray. Pixels that meet the second additional correction judgment condition and are additionally corrected to the third brightness value are shown in light gray, and pixels that are not the primary correction target pixels are shown in white.

Afterwards, actual cross-section hardening is performed based on the 2D slice image on which the pixel correction (S14) step has been performed. Figure 4(d) shows a cross-section of a 3D structure formed by photocuring based on a 2D slice image on which a pixel correction (S14) step was performed.

First, a sufficient amount of light is irradiated to pixels (white pixels) that are not primary correction target pixels. Accordingly, overhardening occurs in the area corresponding to the pixel that is not the primary correction target pixel, and the hardened area extends to the surrounding area of the pixel that is not the primary correction target pixel.

Meanwhile, the cross-sectional hardening of the primary correction target pixel (solid line pixel) whose brightness value was first corrected because it did not meet the pixel additional correction judgment conditions is applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel). It may be performed in such a way that a first amount of light less than 20% of the amount of light applied is irradiated. Accordingly, the first correction target pixel is cured with a relatively very low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and overcuring may not occur.

Meanwhile, the cross-sectional hardening of the primary correction target pixel (dark gray pixel) whose brightness value has been additionally corrected by meeting the first additional correction judgment condition is similar to FIG. 3, as shown in FIG. It may be performed in such a way that a second amount of light, which is smaller than the amount of light applied to the pixel and greater than 20% but less than 100% of the first amount of light, is irradiated. Accordingly, the primary correction target pixel, whose brightness value of the pixel has been additionally corrected by satisfying the first additional correction judgment condition, is cured with a relatively low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and over-curing does not occur. It may not be possible.

Finally, the cross-sectional hardening of the primary correction target pixel, whose brightness value has been additionally corrected by satisfying the second additional correction judgment condition, is less than the amount of light applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel). , It can be performed in a way that a third amount of light that is greater than the first amount of light is irradiated. For example, cross-section curing of the second additionally corrected target pixel (light gray pixel) may be performed by irradiating a third amount of light that is 50% to 100% of the amount of light applied to the pixel before correction. Accordingly, the primary correction target pixel, whose brightness value of the pixel has been additionally corrected by satisfying the second additional correction judgment condition, is cured with a relatively low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and over-curing does not occur. It may not be possible.

A sufficient amount of light is irradiated to pixels that are not primary correction target pixels, and a relatively very low amount of light compared to the sufficient light amount is irradiated to the primary correction target pixels that have been primarily corrected, and the additionally corrected primary correction target pixels A relatively low amount of light is irradiated compared to the sufficient amount of light. Accordingly, overhardening occurs in the area corresponding to the pixel that is not the primary correction target pixel, and overhardening occurs in the area corresponding to the primary correction target pixel and the area corresponding to the additionally corrected primary correction target pixel. It doesn't work. Therefore, ultimately, as shown in (d) of FIG. 4, a cross-section with the same shape as the initially intended slice image ((a) of FIG. 4) can be formed. Figure 4(d) shows a cross-section of a 3D structure formed by actual photocuring.

Figures 5 (a) to (d) are diagrams to explain another example of determining correction conditions and performing correction in an image processing method for high-precision ceramic 3D printing.

Figure 5(a) illustrates another example of a 2D slice image. First, in the first correction target pixel selection (S12) step, the outermost and innermost border pixels of the 2D slice image are selected. The selected primary correction target pixel is shown in (b) of FIG. 5.

Thereafter, in the pixel additional correction condition determination step (S13), it is determined whether the selected primary correction target pixel satisfies the pixel additional correction condition and it is decided whether to perform primary correction or additional correction.

At this time, it is determined whether the primary correction target pixel, among the primary correction target pixels that do not satisfy the first additional correction judgment condition and the second additional correction judgment condition, is arranged horizontally or vertically and in only one line. For convenience of explanation, the case of determining whether the pixels subject to primary correction are arranged in only one line horizontally or in only one line vertically is defined as the “third additional correction judgment condition.”

Next, in the pixel correction (S14) step, additional correction is performed on the primary correction target pixel that satisfies the third additional correction determination condition among the primary correction target pixels. In other words, the brightness value of the primary correction target pixel that is arranged horizontally or vertically in only one line and satisfies the third additional correction judgment condition among the primary correction target pixels is divided into the pixel before correction (or the normal pixel that is not the primary correction target pixel). ) is corrected to a fourth brightness value that is smaller than the brightness value and larger than the first brightness value. For example, if the primary correction target pixels are arranged horizontally or vertically in one continuous line, the brightness value of the primary correction target pixels, which are horizontally or vertically continuous in only one line, is set to 50% of the brightness value of the pixel before correction. It can be corrected to a fourth brightness value of less than 100%. Accordingly, the primary correction target pixel, whose brightness value of the pixel has been additionally corrected by meeting the third additional correction judgment condition, is cured with a relatively low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and over-curing does not occur. It may not be possible. Figure 5 (c) shows an example of additional correction of the brightness value of the first correction target pixel that satisfies the third additional correction determination condition. That is, pixels that satisfy the third additional correction determination condition and are additionally corrected to the fourth brightness value are shown in light gray.

Afterwards, actual cross-section hardening is performed based on the 2D slice image on which the pixel correction (S14) step has been performed. Figure 5(d) shows a cross-section of a 3D structure formed by photocuring based on a 2D slice image on which a pixel correction (S14) step was performed.

Meanwhile, the cross-sectional hardening of the primary correction target pixel, whose brightness value of the pixel has been additionally corrected by satisfying the third additional correction judgment condition, is less than the amount of light applied to the pixel before correction (or a normal pixel that is not a primary correction target pixel), It may be performed in such a way that a fourth light quantity greater than the first light quantity is irradiated. For example, cross-sectional curing of a pixel (light gray pixel) that has been additionally corrected by meeting the third additional correction judgment condition is performed by irradiating light with a fourth light amount of 50% to 100% of the light amount applied to the pixel before correction. It can be. Accordingly, the primary correction target pixel, whose brightness value of the pixel has been corrected by satisfying the third additional correction judgment condition, is cured with a relatively low amount of light compared to the sufficient amount of light, so that only the area corresponding to the pixel can be selectively cured, and over-curing will not occur. You can. A relatively low amount of light compared to the sufficient amount of light is irradiated to the additionally corrected primary correction target pixel. Therefore, as finally shown in (d) of FIG. 5, a cross-section with the same shape as the initially intended slice image ((a) of FIG. 5) can be formed. Figure 5(d) shows a cross-section of a 3D structure formed by actual photocuring.

Figures 6 (a) and (b) are 2D slice images before and after image processing is completed according to the image processing method for high-precision ceramic 3D printing.

Figure 6 shows a 2D slice image of an artificial molar tooth, Figure 6(a) shows a 2D slice image before border pixel correction, and Figure 6(b) shows a 2D slice image after border pixel correction.

In the 2D slice image in (a) of Figure 6, the outermost and innermost pixels are selected as the primary correction target pixels, and it is determined whether the above-described correction conditions are met for the selected primary correction target pixel, and the correction conditions are determined. Pixel brightness values are corrected for pixels that meet the requirements. A 2D slice image with complete brightness value correction is shown in (b) of FIG. 6. As can be seen with reference to Figures 6 (a) and (b), it can be seen that the brightness value of the border pixel of the 2D slice image is lowered as pixel correction is performed.

Figure 7 is a flowchart of a high-precision ceramic 3D printing method according to an embodiment of the present invention.

Referring to FIG. 7, the high-precision ceramic 3D printing method according to an embodiment of the present invention provides a raw material layer on a plate for 3D printing a 3D structure (S21).

Specifically, in the layer provision (S21) step, raw materials for 3D printing a 3D structure may be provided as a layer on the upper part of the stage. A method of providing raw materials in the form of a layer can be performed, for example, by discharging the raw materials on the outside of the stage and then applying them to the front of the stage with a blade. However, it is not limited to this, and may be performed by discharging the raw material in a line form and applying it to the stage.

At this time, the raw material provided in the form of a layer can be applied to the front of the stage at a thickness of 1㎛ or more and 100㎛ or less. In the present invention, the raw material provided in layer form can preferably be produced with a thickness of 50㎛.

Raw materials for 3D printing can be created by mixing ceramic pigments and photocurable resin.

The ceramic pigment may be made of at least one of oxide ceramics, carbide ceramics, nitride ceramics, and non-oxide ceramics. For example, the ceramic pigment of the present invention may be an oxide ceramic such as zirconia (ZrO ₂ ), yttria (Y ₂ O ₃ ), etc.

Photocurable resin is a resin that undergoes polymerization by light and includes a photocurable monomer and a photoinitiator.

The photocurable monomer is a diluent that crosslinks the photopolymerization reaction of oligomers and may be composed of an organic material containing one or more acrylate groups. For example, Neopentylglycoldiacrylate (NPGDA), Pentaerythritoltriacrylate (PETIA), and Dicyclopentenyl-oxy-ethyl-Methacrylates. can be used

A photoinitiator is a substance that initiates photopolymerization by generating radicals or cations by light, and includes acrylphosphine oxides (APO), benzyl-dialkylketal (BDK), and diphenyl (2 , 4,6-trimethylbenzoyl) phosphine oxide (TPO), etc. can be used.

Layer photocuring (S22) is a step of irradiating light to the raw material for 3D printing provided on the upper part of the stage based on a 2D slice image generated by an image processing method for high-precision ceramic 3D printing.

Layer photocuring (S22) can be performed in a top-down method, in which light is irradiated from the top of the stage to the bottom, and in a bottom-up method, in which light is irradiated from the bottom to the top of the stage. there is. In the present invention, layer photocuring can preferably be performed in a top-down manner.

The raw materials for 3D printing provided on the stage can be selectively photocured only in the irradiated portion by an irradiation device that selectively irradiates light only to a specific portion. For example, if the brightness value of a pixel is set to 20% or more but less than 100%, the area corresponding to the pixel is irradiated with a light amount of 20% or more but less than 100% of the sufficient light amount, and the brightness value of the pixel is set to 50%. If it is set to less than 100%, a light amount of 50% to 100% of the sufficient light amount is irradiated to the area corresponding to the pixel.

Lamination (S23) can be done by applying a new layer-shaped raw material on top of a layer photocured by an irradiation device and repeating the method of photocuring the applied layer to stack multiple layers.

Specifically, the lamination (S23) step may repeat the layer provision (S21) step and the layer photocuring step (S21) until a primary molded product having the same shape as the 3D image is manufactured.

The primary molding produced through the lamination (S23) step may further include a sintering step. The sintering step can be performed by exposing the primary molding to temperatures above 1000°C. If the sintering step is performed at a temperature of less than 1000°C, the physical properties of the first molded product may deteriorate due to insufficient densification between materials.

The sintering process may be performed within a sintering chamber, and may be performed while maintaining the temperature within the chamber at a constant temperature or may be performed while gradually changing the temperature within the chamber.

With the above-described method, high-precision ceramic 3D structures can be created.

The image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention can prevent the first molded product from differing from the original 3D image due to overcuring.

Specifically, the image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention involves first correction corresponding to the outermost and innermost sides of the 2D slice image selected as the border pixel through the first correction target pixel selection step. It includes the step of first correcting the target pixel to a first brightness value. Accordingly, even if an uncorrected pixel that is not a correction target pixel adjacent to the first correction target pixel is overbrightened by a sufficient amount of light, the first correction target pixel emits a relatively low amount of light compared to the sufficient light amount. Because it is irradiated, the size of the original 3D image and the first molded product can be output the same way. In other words, a sufficient amount of light is provided to the uncorrected pixels rather than the pixels to be corrected, so that the original 3D image and the size of the primary molded product can be output the same even if overcuring due to light scattering occurs.

Meanwhile, an image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention includes a pixel additional correction condition determination step of determining whether the primary correction target pixel meets the additional correction condition and an additional correction target pixel. Since it includes the step of additionally correcting the brightness value of the determined primary correction target pixel, it is determined whether additional correction is required for the pixel selected as the primary correction target pixel, and the pixel can be additionally corrected. Specifically, the brightness value of the primary correction target pixel that satisfies the additional correction condition may be corrected to a brightness value that is different from the brightness value of the first correction target pixel that does not satisfy the additional correction condition. In this case, when the pixel for the thin area of the 3D image is selected as the primary correction target pixel, it is determined that additional correction is satisfied and the brightness value of the primary correction target pixel is corrected, so the brightness value of the primary correction target pixel is corrected. It is possible to prevent pixels from undergoing primary correction.

In addition, a high-precision ceramic 3D printing method using an image processing method for high-precision ceramic 3D printing according to an embodiment of the present invention is a cross-section that satisfies the pixel additional correction determination conditions through various pixel additional correction condition determination methods. It is possible to suppress primary correction of thin areas, and at the same time, it is possible to effectively suppress over-hardening from occurring in thin areas. Specifically, pixels corresponding to areas that should not undergo primary correction are additionally corrected by determining pixel additional correction judgment conditions, and the brightness value of the pixel is corrected. The area corresponding to the primary correction target pixel whose brightness value has been corrected may be irradiated with an amount of light that is the same as the brightness value of the primary correction target pixel whose brightness value has been corrected according to the pixel additional correction determination condition. Accordingly, the thin structure of the primary molded product can be printed without being deleted, and the thin structure is irradiated with an appropriate amount of light that does not cause overcuring, so overcuring cannot be induced in the thin structure of the primary molded product. Therefore, it is possible to improve the forming precision of the primary molded product and at the same time sufficiently induce hardening of the thin structure to suppress cracks generated during the sintering process.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

Claims (10)

A 2D slice image generation step of generating a 2D slice image by slicing the 3D image for 3D printing a 3D structure at an interval corresponding to the thickness of the stack with a cross section perpendicular to the stacking direction;
A primary correction target pixel selection step of selecting a pixel corresponding to an edge of the 2D slice image as a primary correction target pixel;
A pixel additional correction condition determination step of determining whether the pixel subject to primary correction meets a pixel additional correction condition; and
A pixel correction step of additionally correcting the brightness value of the primary correction target pixel corresponding to the pixel additional correction condition, and performing primary correction on the brightness value of the remaining primary correction target pixel that does not correspond to the pixel additional correction condition. An image processing method for high-precision ceramic 3D printing. According to clause 1,
The first correction target pixel selection step is,
A step of selecting outermost and innermost border pixels of the 2D slice image as primary correction target pixels,
The pixel correction step is,
Setting the brightness value of the primary correction target pixel to be the first brightness value,
An image processing method for high-precision ceramic 3D printing, wherein the first brightness value is a brightness value of less than 20% of the brightness value of the pixel before correction. According to clause 2,
The pixel additional correction condition determination step is,
It includes determining whether the primary correction target pixel is a 2x2, 3x3, or 4x4 pixel,
The pixel correction step is,
An image processing method for high-precision ceramic 3D printing, comprising setting the brightness value of the 2x2, 3x3, or 4x4 pixel to a second brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value. . According to clause 2,
The pixel additional correction condition determination step is,
A step of determining whether three or more other primary correction target pixels exist adjacent to one of the primary correction target pixels,
The pixel correction step is,
If there are three or more other primary correction target pixels adjacent to the one primary correction target pixel, the brightness value of the one primary correction target pixel is set to be higher than the brightness value of the pixel before correction. An image processing method for high-precision ceramic 3D printing, comprising setting a third brightness value that is small and greater than the first brightness value. According to clause 2,
The pixel additional correction condition determination step is,
A step of determining whether the primary correction target pixels are arranged horizontally or vertically in a single line,
The pixel correction step is,
Comprising the step of setting the brightness value of the first correction target pixels, which are arranged horizontally or vertically in only one row, to a fourth brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value, Image processing method for high-precision ceramic 3D printing. A layer providing step of providing a raw material layer to a plate for 3D printing a 3D structure;
As a layer photocuring step of irradiating the layer with light,
The light is irradiated based on a corrected 2D slice image obtained by correcting the 3D image of the 3D structure according to correction conditions, which is generated by slicing the 3D image of the 3D structure at intervals corresponding to the stacking thickness as a plane perpendicular to the stacking direction,
The corrected 2D slice image is,
Selecting a pixel corresponding to the border of the 2D slice image as a primary correction target pixel,
Determine whether the pixel subject to primary correction meets pixel additional correction conditions,
Light is partially transmitted to the layer created by additionally correcting the brightness value of the primary correction target pixel corresponding to the pixel additional correction and performing primary correction on the remaining primary correction target pixels that do not correspond to the pixel additional correction conditions. Irradiating layer photocuring step; and
A high-precision ceramic 3D printing method comprising a lamination step of repeating the layer providing step and the cross-section forming step until the 3D structure is manufactured. According to clause 6,
The layer photocuring step is,
Setting the brightness value of the primary correction target pixel to a first brightness value that is less than 20% of the brightness value applied to the pixel before correction,
Comprising the step of irradiating light with a first amount of light to an area corresponding to the primary correction target pixel set to the first brightness value,
The first light quantity is a light quantity less than 20% of the light quantity applied to the pixel before correction,
High-precision ceramic 3D printing method. According to clause 7,
The layer photocuring step is,
Determine whether the primary correction target pixel is a 2x2, 3x3, or 4x4 pixel,
Setting the brightness value of the 2x2, 3x3, or 4x4 pixel to a second brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value,
High precision, comprising the step of irradiating light with a second light quantity smaller than the light quantity applied to the pixel before correction and greater than the first light quantity to an area corresponding to the 2x2, 3x3 or 4x4 pixel set to the second brightness value. Ceramic 3D printing method. According to clause 7,
The layer photocuring step is,
Determine whether 3 or more other primary correction target pixels exist adjacent to one of the primary correction target pixels,
If there are three or more other primary correction target pixels adjacent to the one primary correction target pixel, the brightness value of the one primary correction target pixel is set to be higher than the brightness value of the pixel before correction. set to a third brightness value that is smaller and larger than the first brightness value,
Comprising the step of irradiating light with a third light quantity smaller than the light quantity applied to the pixel before correction and greater than the first light quantity to the area corresponding to the one primary correction target pixel set to the third brightness value. , high-precision ceramic 3D printing method. According to clause 7,
The layer photocuring step is,
Determine whether the primary correction target pixels are arranged horizontally or vertically in only one line,
Setting the brightness value of the pixels arranged horizontally or vertically in a single line to a fourth brightness value that is smaller than the brightness value of the pixel before correction and larger than the first brightness value,
Irradiating light with a fourth light quantity smaller than the light quantity applied to the pixel before correction and greater than the first light quantity to an area corresponding to the pixels arranged in only one horizontally or vertically continuous line set to the fourth brightness value. A high-precision ceramic 3D printing method including.

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