JP2013208845A - Three-dimensional surface printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional surface printing technology which is easy in rewriting and does not need electric power for maintaining display.SOLUTION: A printing method for performing printing on a three-dimensional surface being a non-plane includes: a preparation process for preparing the three-dimensional surface on which a bistability thermochromic material changeable in a color development state and a color fading state which are generated by a difference of heating temperatures and a difference of cooling speeds after heating is arranged; and a printing process for performing printing by selectively heating the three-dimensional surface. It is preferable that a laser may be used in the heating. Furthermore, the printing of an arbitrary color becomes possible by coating a plurality of colors of inks by patterning them and controlling color development and color fading at each sub-pixel unit. When the plurality of colors of the inks are sub-pixelated, the positioning of a radiation position can accurately be performed by measuring a color of a laser-radiated position.

Description

  The present invention relates to a technique for printing on a three-dimensional surface.

In recent years, research on spatial augmented reality has been underway. For example, a method for providing information by projecting an image on a three-dimensional object has been proposed (Non-Patent Document 1). According to this method, the information to be presented can be easily changed by changing the projected image. This effect cannot be obtained by conventional non-planar printing that performs permanent printing on a non-planar surface.

  However, there is a problem that it cannot be applied to daily necessities because it requires electric power to project an image and the surroundings need to be dark. Furthermore, there is a problem that the object cannot be moved from a predetermined projection position.

  There is an electronic paper technology as a technology that can be easily rewritten and does not require power to maintain the display. In electronic paper, an electric field is required for rewriting an image (changing the pixel black and white), so that power is required. However, power is not required to maintain the display state. However, since such a display needs to be manufactured by arranging electronic circuits in a grid pattern, the size of the display area is limited, and the display surface is also a flat surface or a developable surface (a surface that can be expanded into a flat surface without expansion and contraction). ).

JP 2011-525445 A International Publication No. 2005/121072 JP-A-5-124360 JP 2007-182004 A

Dalsgaard, P., and Halskov, K., "3D Projection on Physical Objects: Design Insights from Five Real Life Cases", Proceedings of the 2011 annual conference on Human factors in computing systems, ACM, pp. 1041-1050, 2011 Pfister, H., et. Al., "Surfels: Surface Elements as Rendering Primitives", Proceedings of the 27th annual conference on Computer graphics and interactive techniques, ACM, pp. 335-342, 2000

  An object of the present invention is to provide a three-dimensional surface printing technique for performing printing on a non-planar surface, which is easy to rewrite and does not require electric power to maintain display.

  In order to solve the above-described problem, the printing method according to the first aspect of the present invention provides a bistable thermochromic material on the surface of a printing object, and develops color by selectively heating the bistable thermochromic material. The state and the color erasing state are switched to perform printing on the surface of the printing object.

More specifically, the printing method according to the first aspect of the present invention is a printing method in which printing is performed on a non-planar three-dimensional surface, and coloring is caused by a difference in heating temperature or a cooling rate after heating. A preparatory step of preparing a three-dimensional surface provided with a bistable thermochromic material capable of changing a state and a decoloring state; and a printing step of selectively heating the three-dimensional surface to perform printing.

  According to the present invention, printing can be performed on a surface having an arbitrary shape. In addition, since the bistable thermochromic material does not require electric power to maintain a colored state or a decolored state, the printing object can be moved freely after printing. Furthermore, if heating or cooling is performed again after printing, the printed content can be easily rewritten.

  In the preparation step, a three-dimensional surface provided with the bistable thermochromic material can be prepared by applying the bistable thermochromic material to the three-dimensional surface. Another method is to create a three-dimensional surface to be printed with a material containing a bistable thermochromic material. For example, an object to be printed (for example, clothes or shoes) may be created using fibers having bistable color development characteristics.

  The selective heating in the printing process according to the first aspect of the present invention can be performed by any means, but in order to enable printing with high resolution, it is preferable to perform heating using a laser. . This is because the irradiation area can be reduced by using a laser. However, you may heat by methods other than a laser. For example, the surface of the printed material may be heated by focusing electromagnetic waves or light with a lens, or heated by blowing warm air. In addition, selective heating may be performed by moving the heat source itself in the vicinity of the surface of the printing object. Alternatively, selective heating can be realized by superimposing a material having different specific heat on a metal film or the like on the print object and heating the entire print object.

  In the first aspect of the present invention, a scanning step of scanning a three-dimensional surface of an object to be printed, and the scanned image of the three-dimensional surface taken into the texture editing software are printed on the three-dimensional surface. It is also preferable to perform heating by controlling a laser based on the image data in the printing step.

  By scanning the three-dimensional surface of the printing object, the accurate surface shape can be acquired. Then, by performing printing based on the image data edited using the texture editing software, it is possible to perform printing that faithfully reproduces the image data. In addition, the laser spot diameter is controlled according to the distance between the laser light source and the object to be printed, and the laser irradiation scanning interval is controlled according to the laser irradiation direction and the direction of the three-dimensional surface to make the surface resolution uniform. Or more suitable printing can be performed.

  As the bistable thermochromic material as described above, a material that becomes colored when cooled below the first temperature and becomes decolored when heated above the second temperature higher than the first temperature is used. be able to. When such a bistable thermochromic material is used, the bistable thermochromic material in a colored state is applied in the preparation step, or the bistable thermochromic material is applied after the preparation step. The dimensional surface is cooled to the first temperature or lower, and in the printing process, the portion to be erased is irradiated with a laser to be heated to the second temperature or higher. In this way, it is possible to print an arbitrary print pattern on the three-dimensional surface. In addition, even after printing once, the contents of the print can be easily rewritten.

In addition, as the bistable thermochromic material, a material capable of changing the coloring state and the decoloring state according to the cooling rate after heating can be used. When such a bistable thermochromic material is used, the coloring state and the decoloring state of the bistable thermochromic material can be changed by irradiating lasers having different pulse patterns. For example, heating with a high cooling rate can be realized by irradiating a pulse laser with high intensity for a short time. In addition, irradiation with a pulse laser whose intensity gradually decreases can realize heating with a low cooling rate. According to such a method, it is not necessary to perform cooling when rewriting the print content, and it is only necessary to irradiate the laser only at the position where the coloring and decoloring are rewritten, so that the rewriting of the print content becomes easier. .

  As the bistable thermochromic material, only one color may be used, but a plurality of types of bistable thermochromic materials that develop colors in different colors may be used. When a plurality of types of bistable thermochromic materials are used, it is preferable to pattern these bistable thermochromic materials and apply them to a three-dimensional surface. For example, three colors of red, blue and green (RGB) are applied in a pattern such as a delta arrangement, a stripe arrangement, or a mosaic arrangement, and an arbitrary color can be expressed by controlling color development and decoloration in units of dots. it can.

  When the bistable thermochromic material of a plurality of colors is used in a pattern as described above, the printing process measures the reflected light intensity on the surface when the laser is irradiated on the three-dimensional surface, and the laser irradiation position is measured. It is preferable to include a step of measuring the color of the bistable thermochromic material and a calibration step of determining the irradiation position of the laser based on the measurement. By measuring the color of the bistable thermochromic material by laser irradiation, the laser irradiation position can be accurately grasped. Therefore, accurate printing can be performed.

  The second aspect of the present invention is a three-dimensional surface printing apparatus for suitably carrying out the above-described printing method for printing on a three-dimensional surface provided with a bistable thermochromic material. The three-dimensional surface printing apparatus according to the second aspect of the present invention includes a mounting table for placing a printing object having a non-planar three-dimensional surface, a light source for irradiating a laser, a photosensor, and the laser. A shape acquisition unit that scans a three-dimensional surface to acquire the shape of the three-dimensional surface; a texture editing unit that captures the scanned three-dimensional surface and allows image data to be printed on the three-dimensional surface to be edited by a user; Printing means for controlling the laser based on the image data to heat the three-dimensional surface.

  Since printing is performed on the three-dimensional surface by laser irradiation in this way, printing can be performed on an object having an arbitrary shape. In addition, printing can be performed on an object of any size by increasing the size of the printing apparatus itself.

  The second aspect of the present invention further includes a moving mechanism that relatively moves the mounting table and the light source, and the printing unit heats the three-dimensional surface from a plurality of different directions. It is also preferable. In this way, even if the object cannot be printed entirely by laser irradiation from one direction, the entire surface can be printed. The relative movement of the mounting table and the light source may be realized by moving only one of them, or may be realized by moving both of them.

  In the second aspect of the present invention, the color of the three-dimensional surface at the laser irradiation position is measured based on the reflected light intensity when the three-dimensional surface is irradiated with the laser, and based on the measured color. It is also preferable to further include calibration means for determining the laser irradiation position. By determining the color of the irradiation position, the irradiation position can be grasped more accurately.

  The present invention can be understood as a printing method or a three-dimensional surface printing apparatus including at least a part of the above processes and means. Moreover, it can also be grasped as a program for executing the above method on a computer.

  According to the present invention, it is possible to realize three-dimensional surface printing that is easy to rewrite and does not require power to maintain display.

It is a figure which shows the two stable states of a bistable thermochromic ink. It is a figure which shows the external appearance of a three-dimensional printer. It is a figure which shows the functional block of a three-dimensional printer. It is a flowchart which shows the flow of a three-dimensional printing process. It is a figure which shows the application pattern of a bistable thermochromic ink. It is a figure which shows the pulse pattern of the laser to irradiate. It is a figure which shows another example for implement | achieving color printing.

  Hereinafter, embodiments of a three-dimensional printing method and a three-dimensional printing apparatus according to the present invention will be described with reference to the drawings.

<Bistability thermochromic ink>
In the present embodiment, printing is performed by applying a bistable thermochromic ink to the surface of a printing object and selectively heating the surface. First, the bistable thermochromic ink will be described.

  The bistable thermochromic ink is an ink that can change the color development state according to a temperature change, and has at least two stable states and maintains the color development state unless a new phase change occurs.

  As an example of such an ink, an ink using a material disclosed in Patent Document 2 as an electron-accepting compound (developer) or a ballpoint pen sold under the name of “friction ball” by Pilot Corporation. The ink used is known. As shown in FIG. 1A, this ink changes to a decolored state when heated to 70 ° C. or higher. Once in the decolored state, the decolored state is stably maintained even when cooled to 70 ° C. or lower. And if it cools to -10 degrees C or less, it will change to a coloring state again. After the colored state is reached, the colored state is stably maintained even when heated to -10 ° C or higher.

  It has been confirmed that there is no particular deterioration in the state even when switching between the coloring state and the decoloring state with such an ink is repeated a plurality of times (10 times or more). In addition, as for this ink, inks of various colors such as red, blue, green, yellow, magenta, and black are manufactured. From such a viewpoint, it can be said that the ink described in Patent Document 2 is an ink useful for the present invention. In this specification, this type of ink is referred to as “friction ink”.

  As another example of such a bistable thermochromic ink, it is used for inks using the materials disclosed in Patent Documents 3 and 4 and RECO-View (registered trademark) thermal rewritable film sold by Ricoh Co., Ltd. Ink is known. As shown in FIG. 1B, this ink changes to a colored state when heated to 180 ° C. and rapidly cooled, and stably maintains the colored state. Moreover, it changes to a decoloring state by heating to 120 degreeC and slow-cooling, and maintains a decoloring state stably.

This ink can be said to be an ink useful for the present invention because the coloring state and the decoloring state can be controlled only by heating. Also, the colors that can be used are limited to blue, green, black, and the like as compared with friction ink. However, since it is transparent in the decolored state, printing with various colors can be realized by using this ink as a filter on top of normal ink. In this specification, this type of ink is referred to as “Reco ink”.

  The above two types of inks can be said to be inks that can be suitably used in the present invention. However, even with other inks, dual inks that can control the coloring state and the decoloring state by the difference in heating temperature and cooling rate after heating. Any ink may be adopted as long as it is a stable thermochromic ink.

<Overview>
Here, the outline of the printing method according to the present invention will be described. Basically, the printing method according to the present invention includes the following two steps. The first step is a step of applying the bistable thermochromic ink as described above to the surface of the printing object. The second step is a step of performing printing by selectively heating the surface of the object to be printed on which the bistable thermochromic ink has been applied, and switching between the coloring state and the decoloring state of the bistable thermochromic ink.

  In the step of applying the ink to the printing object, any color ink may be applied. When printing in a single color, only one type of ink needs to be applied. In order to perform multicolor printing, an ink that can change the reflection spectrum may be used, but such a bistable thermochromic ink does not exist at present. Therefore, for example, bistable thermochromic inks of three colors of red (R), green (G), and blue (B) are applied to the subpixels in a pattern. As the sub-pixel pattern, a delta arrangement can be adopted, but a mosaic arrangement or a stripe arrangement may be used. An arbitrary color can be printed by individually controlling the coloring / decoloring state of these subpixels.

  In the step of performing printing by selective heating, it is preferable that the heating region can be finely controlled in order to enable printing with high resolution. From such a viewpoint, it is desirable to heat the surface of the printing object by laser irradiation. Although it varies depending on the performance of the laser light source and the optical system and the irradiation distance, laser irradiation with a spot diameter of several tens of μm to 100 μm can be practically used, and printing can be performed with a resolution of about 250 dpi to 1000 dpi.

  When using ink that switches between the colored state and the decolored state due to the difference in heating temperature, such as friction ink, the printing object can be printed by heating the portion to be decolored with a laser after it is cooled once. Yes. When using an ink that switches between the colored state and the decolored state depending on the difference in the cooling rate after heating, such as the Reco ink, all the state is changed to the decolored state (or colored state) once in the same way as the friction ink. However, the state may be changed as necessary by measuring the color of the irradiation position by irradiating a laser.

  As will be described later, the image data to be printed may be created on the texture editing software as a texture to be pasted on the three-dimensional model of the print target. Then, printing may be performed while moving the laser irradiation position according to the texture data. Since the printing object has a three-dimensional shape, if the entire surface of the object cannot be printed from only one direction, the position of the laser and the printing object may be relatively moved.

<Device configuration>
Next, a three-dimensional printing apparatus suitable for carrying out the three-dimensional printing method of the present invention will be described. FIG. 2 is an external view of the three-dimensional printing apparatus 1 according to this embodiment. FIG. 3 is a block diagram of the three-dimensional printing apparatus 1 according to the present embodiment.

The three-dimensional printing apparatus main body 10 according to the present embodiment includes an RGB laser 12, a galvanometer 13, a photosensor 14, and a turntable 15. The three-dimensional printing apparatus 1 includes a computer 20 and a microcontroller 30, and is controlled according to instructions from the computer 20 via the microcontroller 30. The computer 20 is a normal computer including an arithmetic device, a main storage device, an auxiliary storage device, an input / output device, and the like. The computer 20 functions as a shape acquisition unit 21, a shape data storage unit 22, a texture editing unit 23, a UV texture storage unit 24, and a print control unit 25 when the arithmetic device executes a program.

  In this embodiment, a blue laser diode 12B (405 nm), a red laser diode 12R (650 nm), and a green laser diode 12G (532 nm) are used as the light source of the RGB laser 12. The three color lasers are coupled via a kinematic mount (not shown) and dichroic mirrors 17 and 18 so that the surface of the printing object 100 can be scanned by the biaxial galvanometer 13. If only the surface of the printing object 100 is heated, only one color laser (for example, a blue laser) may be used. In this embodiment, 3 is used to measure the color of ink at the laser irradiation position. Color laser is adopted. As will be described in detail later, the color of the laser irradiation position surface is measured by irradiating each of the three RGB lasers and measuring the wavelength of the reflected light by the photosensor 14.

  The turntable 15 is for placing the printing object 100 and rotates to relatively move the positions of the printing object 100 and the laser 12. This is because the entire surface of the printing object 100 can be printed. In the present embodiment, the distance between the laser 12 and the turntable 15 is 450 to 550 mm.

  The description of each functional unit realized by the computer 20 will be collectively performed in the following description of the printing method.

<Processing method>
FIG. 4 is a flowchart showing a flow of processing for performing printing on a three-dimensional surface using the three-dimensional printing apparatus 1 according to the present embodiment.

  First, the printing object 100 is prepared (S1). The print object 100 is an object to which bistable thermochromic ink can be applied, and may be any object as long as it can be stored in the three-dimensional printing apparatus. The surface of the printing object 100 does not have to be a flat surface, and may have an arbitrary shape.

  Next, the printing object 100 is three-dimensionally scanned to obtain three-dimensional shape data (S2-S3). In the present embodiment, scanning is performed using the same laser used for printing. The shape acquisition unit 21 controls the laser or the like to acquire the three-dimensional shape of the printing object 100 and stores the three-dimensional shape data in the shape data storage unit 22. However, it is not necessary to obtain the shape data of the printing object 100 using the three-dimensional printing apparatus 1, and the three-dimensional shape data may be taken into the computer 20 by being executed by another apparatus.

  Next, the user edits the image data (texture data) to be printed on the surface of the printing object by the texture editing unit 23 (S4 to S5). The texture editing unit 23 can be realized by an existing software program for creating and editing a texture for a three-dimensional surface. When the UV texture data is created by the user, the data is stored in the UV texture storage unit 24.

Further, the bistable thermochromic ink is applied to the surface of the printing object 100 (S6). In this embodiment, in order to realize color printing, three colors of ink of red, blue, and green are applied in a pattern. Here, as shown in FIG. 5, the three colors of RGB are applied in a delta arrangement. The size of each sub-pixel may be adjusted as appropriate according to the resolution required for printing. Here, the size is about 0.1 mm (250 dpi) in diameter. The application of the bistable thermochromic ink can be realized by, for example, a conventional inkjet three-dimensional printing method. Depending on the material and shape of the surface of the printing object, a film coated with bistable thermochromic ink may be attached. Then, the printing object 100 to which the bistable thermochromic ink is applied is placed on the turntable 15 (S8). Here, it has been described that the ink application is performed after the shape is scanned, but the printing object 100 after the ink application may be scanned.

  The print control unit 25 determines an irradiation view suitable for performing laser irradiation on the print object 100 from the three-dimensional shape data and the UV texture data (S9). In addition, in each irradiation view, it is also determined which point of the UV texture is subjected to laser irradiation. The irradiation view suitable for performing laser irradiation is such that the entire surface of the printing object 100 can be irradiated with laser with the smallest possible number of views, and the laser can be irradiated as perpendicularly to the surface of the printing object 100 as possible. It is a view. By appropriately determining the irradiation view, it is possible to shorten the printing time and improve the printing accuracy.

  The following steps S10 to S14 are executed for each irradiation view by the print control unit 25. First, the print control unit 25 rotates the turntable 15 via the microcontroller 30 so as to coincide with the irradiation view obtained in step S9 (S10).

  The following steps S11 to S13 are one-point printing processes by laser heating. These steps are repeated for the number of drawing points in the illuminated view.

  First, the print control unit 25 controls the galvanometer to match the laser irradiation position with a point in the UV texture data. Then, at the irradiation position, a blue laser (10 mW), a red laser (0.4 mW), and a green laser (0.5 mW) are irradiated, and the reflected light is measured by the photosensor 14 (S11). By this process, the RGB value of the irradiation position can be obtained.

  If there is no error, the laser irradiation position can be accurately determined in units of subpixels by controlling the galvanometer based on the irradiation view and the three-dimensional shape data. However, if the resolution of the subpixel is increased, accurate positioning becomes difficult. Therefore, the laser irradiation position control is calibrated by measuring the color of the laser irradiation position. The print control unit 25 can determine how many subpixels the laser irradiation position is based on the color of the laser irradiation position obtained by the above measurement. By including such a calibration process, the laser irradiation position can be controlled with high accuracy.

  The print control unit 25 compares the obtained color (RGB value) with the color at the target point of the UV texture data (S12), and determines whether laser irradiation is necessary. If it is necessary to change the coloring / decoloring at the laser irradiation position, the laser is irradiated to the irradiation position to change the color according to the UV texture data (S13). When using friction ink whose color development state can be controlled by heating temperature, laser is irradiated (50 mW, 50 ms) when changing the ink to the decolored state, and laser irradiation is performed when maintaining the color development state. Not performed. Unlike the calibration process, the laser irradiation for the coloring state may use only one color laser. Any color may be used, but in this embodiment, heating is performed with a blue laser.

When Reco ink that can control the coloring state at the cooling rate after heating is used, the coloring state is changed by changing the pulse pattern of the laser to be irradiated. Specifically, in order to change from the decolored state to the colored state, as shown in FIG.
Are irradiated only once for 100 ms. Thereby, rapid cooling after heating is realized, and the Reco ink changes from a decolored state to a colored state. On the other hand, when erasing ink, as shown in FIG. 6B, five pulses gradually weakening from 150 mW are irradiated at a pulse interval of 50 ms. Thereby, slow cooling after heating is realized, and the Reco ink changes from the colored state to the decolored state. In addition, when the color developing state or the color erasing state is maintained, the laser irradiation is not performed.

  In the laser irradiation described above, the focal spot diameter of the laser and the distance between the spots (laser irradiation density) must be constant even if the distance or angle between the laser light source and the surface to be printed changes. This is because when the focal spot diameter is increased, the heating amount is decreased and the color development state cannot be controlled. This is also because good printing cannot be performed unless the distance between spots is constant. Therefore, in the present embodiment, the print control unit 25 does not perform rasterization processing in the image space, but performs rasterization processing in the object space in the same manner as the method disclosed in Non-Patent Document 2. By controlling the laser spot diameter and the laser scanning interval in consideration of the distance and angle between the laser light source and the surface to be printed in this way, better printing can be achieved.

  It is determined whether or not the processing of S11 to S13 has been executed for all points to be printed in the current irradiation view (S14), and when all of the points are completed, the turntable is rotated to perform laser irradiation in the next irradiation view. Start (S10).

  It is determined whether the processes of steps S10 to S14 have been executed for all the irradiation views (S15). If all the irradiation views are completed, the printing process is completed, and the print target is taken out from the turntable (S16).

  In the above description, the process of applying ink to a print object has been described. However, when printing is performed again on an already printed object, it is not necessary to apply ink. When using ink that can change the coloring state by heating and cooling, such as friction ink, the printing object is cooled before reprinting, and the entire surface is colored, and then the above printing process is performed. Can be done again. In the case of using an ink that can change the color development state due to the difference in the cooling rate after heating, such as the Reco ink, the above-described printing process may be performed again without preprocessing. Of course, also in the case of the Reco ink, the printing process may be started after the entire surface has been colored or decolored in advance.

<Operation / Effect of Embodiment>
In this embodiment, printing is performed by irradiating a laser beam to a bistable thermochromic ink, so that printing can be performed on a non-planar surface and rewriting is also possible. The feature of being rewritable is effective for creating a prototype of a design, for example. In addition, since the coloring state by laser irradiation can be controlled at a relatively high speed, printing can also be realized at a high speed.

  No power or special equipment is needed to hold the printed image. Therefore, the printed object can be moved. Therefore, it is possible to print daily commodities and use them as they are. In general households, the appearance of shoes and bags can be changed relatively easily. In addition, in restaurants and the like, if used for printing advertisements on cups and pens, the contents of advertisements can be changed frequently.

In addition, since the color development state is controlled by laser irradiation, there is an advantage of this embodiment in that there is virtually no restriction on the size of the print object. For example, it is possible to print on the surface of the vehicle. In addition, it is possible to print on road signs, building walls, floors and ceilings.

<Modification>
In the above description, in order to realize color printing, a plurality of colors of ink are applied in a pattern in a delta arrangement. However, the same effect can be obtained even if subpixels are formed by a stripe arrangement or a mosaic arrangement other than the delta arrangement.

  Further, the color printing can be realized by a method different from the above. For example, color printing can be realized using a bistable thermochromic ink that can change between white and black. As shown in FIG. 7 (a), a bistable thermochromic ink is applied to the surface of the printed material, and a color filter formed into sub-pixels is provided thereon. As a result, the portion where the bistable thermochromic ink is white is the color of the color filter, and the portion where the bistable thermochromic ink is black is black.

  Color printing can also be realized using a bistable thermochromic ink that can change between transparent and opaque (black). As shown in FIG. 7B, a pattern formed by sub-pixels using a normal color ink is printed on the surface of the printed material, and a bistable thermochromic ink is applied thereon. As a result, the transparent portion of the bistable thermochromic ink becomes the color of the ink below it, and the opaque portion of the bistable thermochromic ink becomes black.

  In addition, when performing printing in a single color instead of color printing, it is only necessary to apply one color of bistable thermochromic ink to the entire surface of the printing object. The printing process in this case differs from the above embodiment in that the calibration in step S11 in the flowchart of FIG. 4 is not necessary.

  In the above-described embodiment, the bistable thermochromic ink is applied to the surface of the print object. However, if the bistable thermochromic material is included in the print object surface, printing by selective heating can be executed. Therefore, in addition to applying the bistable thermochromic ink to the surface of the printing object, the printing object may be made of a material containing a bistable thermochromic material. For example, clothing or the like can be created using fibers having bistable color development characteristics, and printing can be performed on this.

  In the above embodiment, the print object is moved with respect to the laser using the turntable, but the irradiation view may be changed by other methods. For example, the laser light source may be moved. A reflecting mirror may be installed around the print target so that the entire surface can be irradiated with laser. In the above embodiment, the laser can be irradiated from only one place, but the laser may be irradiated from a plurality of places. By doing in this way, even a larger printing object can be set as a printing object. In particular, for a large printing surface, a form in which the printing apparatus itself moves is considered preferable.

DESCRIPTION OF SYMBOLS 10 3D printing apparatus 12R, 12G, 12B Laser diode 13 Galvanometer 14 Photo sensor 15 Turntable 20 Computer 21 Shape acquisition part 23 Texture edit part 25 Print control part 30 Microcontroller

Claims (11)

A printing method for printing on a non-planar three-dimensional surface,
A preparation step of preparing a three-dimensional surface provided with a bistable thermochromic material capable of changing a colored state and a decolored state by a difference in heating temperature or a cooling rate after heating;
A printing step of selectively heating the three-dimensional surface for printing;
Including printing method. In the printing step, heating is performed using a laser.
The printing method according to claim 1. A scanning step of scanning the shape of the three-dimensional surface;
An editing step of taking the scanned 3D surface into texture editing software and generating image data to be printed on the 3D surface using the texture editing software;
Further including
In the printing step, heating is performed by controlling the laser based on the image data.
The printing method according to claim 2. The bistable thermochromic material is a material that enters a colored state when cooled below the first temperature, and is decolored when heated above the second temperature higher than the first temperature,
Applying the bistable thermochromic material in a colored state in the preparation step, or cooling the three-dimensional surface on which the bistable thermochromic material is applied after the preparation step to the first temperature or less,
In the printing process, the portion to be decolored is irradiated with a laser to be heated to the second temperature or higher.
The printing method according to claim 3. The bistable thermochromic material is a material that can change the colored state and the decolored state according to the cooling rate after heating,
The printing step changes the color development state and the color erasure state of the bistable thermochromic material by irradiating lasers having different pulse patterns.
The printing method according to claim 3. In the preparation step, the bistable thermochromic material is applied to the three-dimensional surface.
The printing method according to claim 1. In the preparation step, a plurality of types of bistable thermochromic materials that develop different colors are patterned and applied to the three-dimensional surface.
The printing method according to claim 6. The printing process includes
Measuring the reflected light intensity on the surface when the laser is irradiated on the three-dimensional surface, and measuring the color of the bistable thermochromic material at the laser irradiation position;
A calibration step of determining an irradiation position of the laser based on the measurement;
including,
The printing method according to claim 7. A mounting table for mounting a printing object having a non-planar three-dimensional surface;
A light source for irradiating a laser;
A photo sensor,
Shape acquisition means for acquiring the shape of the three-dimensional surface by scanning the three-dimensional surface with the laser;
Texture editing means for capturing a scanned three-dimensional surface and enabling a user to edit image data to be printed on the three-dimensional surface;
Printing means for heating the three-dimensional surface by controlling the laser based on the image data;
A three-dimensional surface printing apparatus comprising: A moving mechanism for relatively moving the mounting table and the light source,
The printing means heats the three-dimensional surface from a plurality of different directions.
The three-dimensional surface printing apparatus according to claim 9. Calibration means for measuring the color of the three-dimensional surface at the laser irradiation position based on the reflected light intensity when the laser is irradiated on the three-dimensional surface, and determining the laser irradiation position based on the measured color In addition,
The three-dimensional surface printing apparatus according to claim 9 or 10.

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