METHOD FOR FORMING BRAILLE TEXT AND INKJET PRINTER

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2017-092895 filed on May 9, 2017 and Japanese Patent Application No. 2018-056874 filed on Mar. 23, 2018. The entire contents of each application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION
1. Field of the Invention

The present invention relates to a method for forming braille text and an inkjet printer.

2. Description of the Related Art

ADA (Americans with Disabilities Act of 1990)-compliant braille text and 3D signage have been used in the art. Braille text is produced by, for example, embossing, and 3D signage is produced by machining, molding, or any other of various techniques.

For example, Japanese Laid-Open Patent Publication No. Hei8-175029 discloses a technique for producing braille text, albeit Japanese braille, by heating a thermal transfer sheet having a thermal expansion layer by means of a thermal head.

It is difficult to produce braille text in a simple and quick manner because it requires embossing a recording medium, etc. It is also difficult to produce 3D signage in a simple and quick manner because the production requires machine tools, molding machines, molds, etc.

SUMMARY OF THE INVENTION

A method for forming braille text on a recording medium according to a preferred embodiment of the present invention is a method for forming braille text on a recording medium, the braille text including a plurality of cells including one or more dots arranged in each cell, at least one of the cells including a plurality of dots arranged therein, the method including discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium; and discharging a photocurable ink onto the print layer and curing with light the discharged photocurable ink, thus forming one or more additional print layer on the print layer. The step of forming at least one of the print layer and the additional print layer includes the step of repeating the discharging and curing of the photocurable ink and an operation of moving the recording medium in a first direction over a first distance; and the first distance is greater than an intra-cell dot-to-dot spacing in the first direction.

With methods for forming braille text according to preferred embodiments of the present invention, it is possible to easily form braille text using a method for forming a plurality of print layers with a photocurable ink.

An inkjet printer for forming braille text on a recording medium according to a preferred embodiment of the present invention, the braille text including a plurality of cells with one or more dots arranged in each cell, at least one of the cells including a plurality of dots arranged therein, includes an ink head including a plurality of nozzles arranged in line in a first direction that discharge a photocurable ink onto the recording medium; a conveyor that moves the ink head in a second direction that is perpendicular or substantially perpendicular to the first direction; a photoirradiator that outputs light to cure the photocurable ink onto the recording medium; a feeder that moves the recording medium in the first direction; and a controller configured or programmed to include a print controller that controls the ink head, the conveyor, the photoirradiator, and the feeder so as to produce the braille text with the photocurable ink on the recording medium. The print controller is configured or programmed to include a feed amount setter, a feed controller, a discharge controller, a moving controller and an irradiation controller. The feed amount setter sets an amount by which the recording medium is fed per one iteration. The feed controller controls the feeder so as to feed the recording medium in the first direction by the feed amount set by the feed amount setter per one iteration. The discharge controller controls the ink head so as to discharge the photocurable ink onto the recording medium between a feed operation and another feed operation by the feeder. The moving controller controls the conveyor so as to move the ink head in the second direction between a feed operation and another feed operation by the feeder. The irradiation controller controls the photoirradiator so as to output light onto the photocurable ink having been discharged onto the recording medium between a feed operation and another feed operation by the feeder. The feed amount setter is configured or programmed so that it is possible to set the feed amount to be greater than an intra-cell dot-to-dot spacing in the first direction.

With the inkjet printers according to preferred embodiments of the present invention described above, it is possible to easily and quickly form braille text using a method for forming a plurality of print layers with a photocurable ink.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an inkjet printer according to a preferred embodiment of the present invention.

FIG. 2 is a front view of a main portion of the inkjet printer.

FIG. 3 shows a configuration of the bottom surface of the carriage.

FIG. 4 shows a configuration of braille text.

FIG. 5 is a vertical cross-sectional view of a dot of braille text.

FIG. 6A is a vertical cross-sectional view of a second print layer in the first step after the start of formation.

FIG. 6B is a vertical cross-sectional view of the second print layer at the time of a pass following that of FIG. 6A.

FIG. 6C is a vertical cross-sectional view of the second print layer upon completion of the layer-stacking printing in the first area.

FIG. 7 shows the relationship between the recording medium feed length and the dot arrangement.

FIG. 8 shows an exemplary 3D print.

FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8.

FIG. 10 is a block diagram of an inkjet printer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described with reference to the drawings. The preferred embodiments described herein are not intended to limit the scope of the present invention. Elements or components having the same or similar function will be denoted by the same reference signs, and redundant descriptions will be omitted or simplified. In the following description, when an inkjet printer is seen from the front side, the direction away from the inkjet printer will be referred to as “front” and the direction towards the inkjet printer as “rear”. The character “Y” in the figures denotes the primary scanning direction and the character “X” the secondary scanning direction perpendicular or substantially perpendicular to the primary scanning direction Y. Of the primary scanning direction Y, the direction that corresponds to the leftward direction of the inkjet printer is denoted as “first primary scanning direction Y1” and the direction that corresponds to the rightward direction thereof as “second primary scanning direction Y2”. Of the secondary scanning direction X, the direction that corresponds to the rearward direction of the inkjet printer is denoted as “upstream X1” and the direction that corresponds to the forward direction thereof as “downstream X2”. The designations F, Rr, L, R, U and D, as used in the figures, refer to front, rear, left, right, up and down, respectively. Note, however, that these designations of direction are used merely for the purpose of illustration, and do not limit how the inkjet printer is installed or configured.

First Preferred Embodiment

FIG. 1 is a perspective view of an inkjet printer 10 according to a first preferred embodiment of the present invention. The inkjet printer 10 includes a casing 2, and a platen 4 that supports a recording medium 5.

FIG. 2 is a front view showing the main portion of the inkjet printer 10. The main portion is arranged inside the casing 2. The inkjet printer 10 includes a guide rail 3 provided in the casing 2. The guide rail 3 extends in the primary scanning direction Y and is secured on the left wall and the right wall of the casing 2. A carriage 1 is in engagement with the guide rail 3. The carriage 1 includes an ink discharge head 21 mounted thereon.

FIG. 3 shows a configuration of the bottom surface of the carriage 1. As shown in FIG. 3, the ink discharge head 21 is mounted on the bottom surface of the carriage 1. The ink discharge head 21 includes six ink heads 21C, 21M, 21Y, 21K, 21W and 21C1. The ink heads 21C, 21M, 21Y, 21K, 21W and 21C1 are arranged in line in the primary scanning direction Y. Each of the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1 includes a plurality of nozzles 24 that are arranged in line in the secondary scanning direction X. The pitch of the nozzles 24 is preferably the same or substantially the same for all of the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1. The number of nozzles 24 is also preferably the same or substantially the same for all of the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1. The positions of the nozzles 24 in the secondary scanning direction X are preferably the same or substantially the same for the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1.

As shown in FIG. 3, each of the ink heads 21C to 21C1 includes a plurality of nozzles 24 arranged in line in the secondary scanning direction X with the pitch P1. The pitch P1 is preferably about 0.14 mm, for example. However, the pitch P1 of the nozzles 24 on each of the ink heads 21C to 21C1 is not limited thereto.

As shown in FIG. 2, the inkjet printer 10 includes an ink tank 11 storing ink therein. The inks stored therein are UV-curable inks that cure when irradiated with UV light. The ink tank 11 includes ink tanks 11C, 11M, 11Y, 11K, 11W and 11C1 preferably storing therein a cyan ink, a magenta ink, a yellow ink, a black ink, a white ink and a clear ink, respectively, for example. Note, however, that there is no particular limitation on the colors of the inks. Although inks of four colors are preferably used as color inks in the present preferred embodiment, the number of color inks used in the inkjet printer 10 is not limited to four. While two types of inks, i.e., a white ink and a clear ink, for example, are preferably used as special color inks other than color inks, the special color inks to be used in the inkjet printer 10 are not limited thereto. There is no particular limitation on the number of ink tanks 11.

The ink heads 21C, 21M, 21Y, 21K, 21W and 21C1 are connected to the ink tanks 11C, 11M, 11Y, 11K, 11W and 11C1, respectively, through ink paths 14. The inkjet printer 10 includes an ink path 14 connected to the ink head 21C and the ink tank 11C, an ink path 14 connected to the ink head 21M and the ink tank 11M, an ink path 14 connected to the ink head 21Y and the ink tank 11Y, an ink path 14 connected to the ink head 21K and the ink tank 11K, an ink path 14 connected to the ink head 21W and the ink tank 11W, and an ink path 14 connected to the ink head 21C1 and the ink tank 11C1. While there is no particular limitation on the structure and the material of the ink paths 14, resin tubes, for example, are preferably used in the present preferred embodiment. The ink paths 14 supply inks from the ink tanks 11C, 11M, 11Y, 11K, 11W and 11C1 to the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1, respectively. The ink paths 14 include pumps 15 that pump the inks from the ink tanks 11C, 11M, 11Y, 11K, 11W and 11C1 towards the ink heads 21C, 21M, 21Y, 21K, 21W and 21C1, respectively. Note, however, that the pumps 15 may not be necessary and may be omitted. A portion of the ink paths 14 extends in the left-right direction and is wrapped around by a cable protecting/guiding device 7.

The carriage 1 includes a first UV lamp 25a and a second UV lamp 25b. The first UV lamp 25a is disposed on the left side of the ink discharge head 21. The second UV lamp 25b is disposed on the right side of the ink discharge head 21.

The carriage 1 is capable of being slid by a carriage conveyor 8 in the primary scanning direction Y along the guide rail 3. The carriage conveyor 8 includes pulleys 8b and 8c disposed at the right end side and the left end side, respectively, of the guide rail 3. A carriage motor 8a is linked to the pulley 8b. The pulley 8b is driven and rotated by the carriage motor 8a. An endless belt 6 is wound around the pulleys 8b and 8c. The carriage 1 is secured on the belt 6. The belt 6 runs as the pulleys 8b and 8c rotate, thus moving the carriage 1 in the primary scanning direction Y.

The recording medium 5 is fed by a feeder 9 downstream X2 in the secondary scanning direction X. The platen 4 is provided under the carriage 1. A pinch roller 9b that holds down the recording medium 5 is provided over the platen 4. A grid roller 9c is provided under the pinch roller 9b. The grid roller 9c is linked to a feed motor 9a. The grid roller 9c is driven and rotated by the feed motor 9a. As the grid roller 9c rotates with the recording medium 5 sandwiched between the grid roller 9c and the pinch roller 9b, the recording medium 5 is fed downstream X2 in the secondary scanning direction X.

The recording medium 5 is a medium on which the discharged ink lands, thus forming a print on the surface thereof. There is no particular limitation on the material and the configuration of the recording medium 5. For example, the recording medium 5 may be a sheet or film of paper or resin, or may be a plate of wood, metal or resin.

The inkjet printer 10 includes a controller 30. Although there is no particular limitation on the hardware configuration thereof, the controller 30 may preferably be a computer including a CPU, a ROM, a RAM, and other components. The controller 30 is connected to the carriage motor 8a, the feed motor 9a, the ink discharge head 21 and the first and second UV lamps 25a and 25b so that the controller 30 is able to communicate with, and control, these elements. The controller 30 controls the carriage motor 8a, the feed motor 9a, the ink discharge head 21, and the first and second UV lamps 25a and 25b in order to print on the recording medium 5.

FIG. 10 is a block diagram of an inkjet printer 10. As shown in FIG. 10, the controller 30 is connected to the carriage motor 8a, the feed motor 9a, the ink discharge head 21, and the first and second UV lamps 25a and 25b, and controls the operation of these components. The controller 30 preferably is configured or programmed to include a print controller 31 and a size setter 32. The print controller 31 controls the ink heads 21C to 21C1, the carriage conveyor 8, the first UV lamp 25a, and the second UV lamp 25b, which are photoirradiators, and the feeder 9 so as to form braille text on the recording medium 5 with the photocurable ink. The print controller 31 may also control these various components so as to form a 3D print on the recording medium 5 with the photocurable ink. Note that the print controller 31 may not be a single processor that controls the ink heads 21C to 21C1, the carriage conveyor 8, the first UV lamp 25a and the second UV lamp 25b, and the feeder 9, but may be a plurality of processors that respectively control these components. The size setter 32 is a processor that sets the size of the photocurable ink discharged from the nozzles 24. As shown in FIG. 10, the print controller 31 preferably is configured or programmed to include a feed amount setter 31A, a feed controller 31B, a discharge controller 31C, a moving controller 31D and an irradiation controller 31E.

The feed amount setter 31A sets the amount by which the recording medium 5 is fed per one iteration.

The feed controller 31B controls the feeder 9 so as to feed the recording medium 5 in the secondary scanning direction X by the feed amount set by the feed amount setter 31A per one iteration.

The discharge controller 31C controls the ink heads 21C to 21C1 so as to discharge the photocurable ink onto the recording medium 5 between a feed operation and another feed operation by the feeder 9.

The moving controller 31D controls the carriage conveyor 8 so as to move the ink heads 21C to 21C1 in the primary scanning direction Y between a feed operation and another feed operation by the feeder 9.

The irradiation controller 31E controls the first UV lamp 25a and the second UV lamp 25b so as to output light onto the photocurable ink having been discharged onto the recording medium 5 between a feed operation and another feed operation by the feeder 9.

The controller 30 may include processors, which will not be described herein, other than the print controller 31 and the size setter 32.

In the first preferred embodiment, the inkjet printer 10 forms braille text on the recording medium 5. FIG. 4 shows a configuration of braille text formed by the inkjet printer 10 according to the present preferred embodiment. Each letter 100 of braille text shown in FIG. 4 includes a maximum of six dots 101. The dots 101 are formed three-dimensionally on the recording medium 5. Braille text represents an alphabet letter based on the presence/absence of a dot 101 at each of the six predetermined positions. Each circle in FIG. 4 that is hatched and delimited by a solid line represents a position at which the dot 101 is formed on the recording medium 5. Each circle in FIG. 4 that is delimited by a two-dot-chain line represents a position at which the dot 101 is absent on the recording medium 5. Adjacent dots 101 in each letter are spaced apart from each other by a predetermined distance (the dot-to-dot spacing L1) in the primary scanning direction Y and in the secondary scanning direction X. In the description of the present preferred embodiment, the rectangular shape that circumscribes six dots 101 is referred to as a cell 102. Adjacent cells 102, i.e., adjacent letters 100, are spaced apart from each other by a predetermined distance (the inter-cell spacing L2) in the primary scanning direction Y and in the secondary scanning direction X.

Braille text shown in FIG. 4 is formed from ink discharged from the ink discharge head 21 of the inkjet printer 10. Braille text is a print produced by the inkjet printer 10. While there is no particular limitation on the types of ink used for braille text, a white ink and a clear ink, for example, are preferably used herein.

FIG. 5 is a vertical cross-sectional view of a dot 101 of braille text. Note, however, that FIG. 5 is a schematic view, and may not necessarily represent the actual proportions of the various portions. Braille text of FIG. 5 includes three print layers. A first print layer Ly1, of the three print layers, is formed directly on the recording medium 5. The first print layer Ly1 is the lowermost layer of the three print layers. The first print layer Ly1 is formed from the clear ink. A second print layer Ly2 is formed directly on the first print layer Ly1. The second print layer Ly2 is also formed from the clear ink. A third print layer Ly3 is formed directly on the second print layer Ly2. The third print layer Ly3 is the uppermost layer of the three print layers. The third print layer Ly3 is formed from the white ink.

The first print layer Ly1 according to the present preferred embodiment is preferably a “matte” print layer of the clear ink. The matte print layer has relatively large surface irregularities, thus resulting in a glossless finish. During the formation of the first print layer Ly1, the controller 30 causes the clear ink to be discharged from the ink head 21C1 while moving the carriage 1 in the primary scanning direction Y. The controller 30 causes the clear ink to be discharged from the ink head 21C1 while moving the carriage 1 in the first primary scanning direction Y1 (leftward). The print direction of the inkjet printer 10 according to the present preferred embodiment is the first primary scanning direction Y1. When discharging the clear ink, the second UV lamp 25b outputs UV light towards the recording medium 5. The second UV lamp 25b is disposed on the second primary scanning direction Y2 (rightward) side relative to the ink discharge head 21. That is, the second UV lamp 25b is disposed rearward in the print direction. When forming the first print layer Ly1, the clear ink is cured by UV light output from the second UV lamp 25b immediately after being discharged. Thus, the clear ink is cured while its graininess still remains. Therefore, relatively large irregularities remain on the surface of the matte print layer. In this process, the first UV lamp 25a does not need to be lit. The controller 30 moves the carriage 1 over the print area, scanning the print area in the first primary scanning direction Y1, thus forming a print layer for one scanning line. Then, the carriage 1 is returned in the second primary scanning direction Y2. The inkjet printer 10 according to the present preferred embodiment does not discharge ink at this point. The second primary scanning direction is the return direction.

During the discharge operation of the ink head 21C1, the discharge controller 31C of the controller 30 controls the ink head 21C1 so that ink dots are formed with an intended resolution in the primary scanning direction Y. The ink dot resolution is included in the braille text print data, for example. In other words, the resolution is the density with which ink dots are formed. The ink dot formation density may be represented by the minimum landing spacing of photocurable ink in the primary scanning direction Y (the shortest spacing between photocurable ink droplets upon landing). For example, where two ink dots include a first ink dot and a second ink dot, the discharge controller 31C is configured or programmed such that the photocurable ink is discharged so as to form a first ink dot and the photocurable ink is discharged so as to form a second ink dot with at least the minimum landing spacing therebetween in the primary scanning direction Y. The minimum landing spacing is determined by the moving speed of the carriage 1 and the time interval at which photocurable ink droplets are discharged. The discharge controller 31C controls the minimum landing spacing to an intended distance by controlling the time interval at which ink droplets are discharged from the ink heads 21C to 21C1. The minimum landing spacing is preferably about 0.07 mm, for example.

After forming a print layer for one scanning line, the controller 30 drives the feed motor 9a to feed a predetermined length of the recording medium 5 downstream X2. The predetermined length is the length Lh shown in FIG. 3. The length Lh is equal or substantially equal to the pitch of the nozzles 24 multiplied by the number of nozzles 24. The controller 30 feeds a length Lh of the recording medium 5 downstream X2 per one iteration. Thus, an unprinted area of the recording medium 5 is moved under the ink discharge head 21. The controller 30 similarly discharges and cures ink on this unprinted area of the recording medium 5. The inkjet printer 10 forms the first print layer Ly1 by repeating this operation until the carriage 1 scans across the entire print area. Thus, for the thickness direction, the first print layer Ly1 is formed from a single shot of clear ink.

The length Lh is preferably about 25.4 mm, for example. However, the length Lh is not limited thereto. Herein, the length Lh is the maximum value of the length over which the recording medium 5 is able to be fed downstream X2. The feed amount by which the recording medium 5 is fed downstream X2 per one feed is Lh/N (N is a natural number). Under print conditions for forming the first print layer Ly1, N is 1. Under print conditions for a different print layer, N may be set to a different value. Note that N may hereinafter also be referred to as the “number of layers”.

The second print layer Ly2 is formed on the first print layer Ly1. The second print layer Ly2 according to the present preferred embodiment is preferably a “glossy” print layer of the clear ink, for example. The surface irregularities of the glossy print layer are relatively small, and the surface of the glossy print layer therefore has a glossy finish. Between the formation of the first print layer Ly1 and the formation of the second print layer Ly2, the recording medium 5 is once returned to the upstream X1 side. Then, the formation of the second print layer Ly2 is started. During the formation of the second print layer Ly2, the first UV lamp 25a is lit. The second UV lamp 25b is turned off. The first UV lamp 25a is disposed on the first primary scanning direction Y1 (leftward) side relative to the ink discharge head 21. The first UV lamp 25a is disposed on the front side in the print direction. In other words, the first UV lamp 25a is disposed on the rear side in the return direction. During the formation of the second print layer Ly2, the controller 30 causes the clear ink to be discharged from the ink head 21C1 while moving the carriage 1 in the first primary scanning direction Y1. The discharged ink is cured by UV light output from the first UV lamp 25a while the carriage 1 is being returned in the second primary scanning direction Y2. In the formation of the second print layer Ly2, an amount of time that is one scanning period or longer passes between discharging ink and curing ink. The first amount of time refers to the amount of time to pass since the ink is discharged until the ink is irradiated with UV light when forming the first print layer Ly1, for example, and the second amount of time is the amount of time to pass since the ink is discharged until the ink is irradiated with UV light when forming the second print layer Ly2. The second amount of time is preferably longer than the first amount of time. The clear ink flattens by virtue of gravity over the second amount of time, thus forming a relatively smooth surface.

As described above, even if print layers are formed from the same clear ink, the texture will differ between the print layers depending particularly on the amount of time between discharging the ink and curing the ink. In order to obtain an even smoother surface for the glossy print layer, the amount of clear ink per shot may be less than that for the matte print layer. Decreasing the droplet size of the discharged clear ink will make the surface of the cured ink even smoother. However, by decreasing the amount of ink to be discharged and by waiting for the ink to flatten before the ink is cured, the print layer to be formed from a single shot of ink will be thin.

When forming the second print layer Ly2, the controller 30 moves the recording medium 5 downstream X2 over a predetermined distance that is shorter than that when forming the first print layer Ly1. For example, the feed length is preferably about 1/10 the feed length Lh used when forming the first print layer Ly1.

FIG. 6A is a vertical cross-sectional view of the second print layer Ly2 in the first step after the start of formation. A first area A1 of FIG. 6A is an area of the second print layer Ly2 that is located at the downstream X2 end. In the first step, the controller 30 causes the clear ink to be discharged from a subset of nozzles 24 of the ink head 21C1 that are provided at the upstream X1 end, and the discharged clear ink is cured, thus forming the first area A1. The length of the first area A1 in the secondary scanning direction X is preferably about Lh/10, for example. The height of the first area A1 from the upper surface of the first print layer Ly1 is Tu as shown in FIG. 6A. The height Tu is the height of a layer to be formed from a single shot of ink. In the following second step, the controller 30 moves the recording medium 5 downstream X2 over the feed length of about Lh/10.

FIG. 6B is a vertical cross-sectional view of the second print layer Ly2 at the time of a pass following that of FIG. 6A. A second area A2 is an area of the second print layer Ly2 that is located upstream X1 of the first area A1. In the third step, following the second step, the second area A2 is formed from the clear ink discharged from the subset of nozzles 24 of the ink head 21C1 that are provided at the upstream X1 end in the secondary scanning direction X. The subset of nozzles 24 are those nozzles 24 that have discharged ink onto the first area A1 in FIG. 6A. The length of the second area A2 in the secondary scanning direction X is preferably about Lh/10, for example. The height of the second area A2 from the upper surface of the first print layer Ly1 is Tu. In the third step, simultaneously with the formation of the second area A2, an additional shot of the clear ink is discharged also onto the first area A1 and is cured. The subset of nozzles 24 that discharge ink onto the first area A1 in this step are provided downstream X2 of the subset of nozzles 24 that are discharging ink onto the second area A2. Thus, the subset of nozzles that discharge ink onto the first area A1 in the first step are different from the subset of nozzles that discharge ink onto the first area A1 in the third step. Conversely, the subset of nozzles that discharge ink onto the first area A1 in the first step are preferably the same as the subset of nozzles that discharge ink onto the second area A2 in the third step. As a result of the third step, a layer having the height Tu is further stacked on the first area A1. At the time of FIG. 6B, the height of the first area A1 is 2Tu. The height of the first area A1 at the time of FIG. 6B is greater, by the height Tu, than the height of the second area A2.

The second print layer Ly2 is formed by repeating these three steps preferably ten times, for example. FIG. 6C is a vertical cross-sectional view of the second print layer Ly2 upon completion of the layer-stacking printing in the first area A1. At the time of FIG. 6C, ten layers are stacked together in the first area A1. The height of the first area A1 is about 10Tu. The height of the second area A2 is about 9Tu. Until the stacking of ten layers is completed in the first area A1, there will always be one more layer in the first area A1 than in the second area A2. Accordingly, the height of the first area A1 will always be higher by Tu than the height of the second area A2. This similarly holds true for the difference between the height of the second area A2 and the height of a third area A3 that is located upstream X1 of the second area A2. This also holds true for a fourth area A4 to a tenth area A10. The second print layer Ly2 is cascaded down towards the upstream X1 side in the secondary scanning direction X. In practice, however, every step portion sags down, so as to form a smooth slope. After the point in time shown in FIG. 6C, the first area A1 is moved downstream X2 of the ink head 21C1. Thereafter, during the formation of the second print layer Ly2, no ink is discharged onto the first area A1. Thus, for the thickness direction, the second print layer Ly2 is formed from ten shots of the clear ink. For the length Lh, the controller 30 moves the recording medium 5 downstream X2 ten times.

In the formation of the second print layer Ly2, a glossy print layer is formed so as to give a smooth finish to the surface of the braille text. By giving a glossy finish, a print layer to be formed from a single shot will be thin, but this is compensated for by stacking ten layers.

The feed amount to form the second print layer Ly2 is set by the feed amount setter 31A of the controller 30. Herein, the feed amount setter 31A sets the feed amount to form the second print layer Ly2 based on the number of layers N. The feed amount to form the second print layer Ly2 is set to the length Lh/N. The number of layers N is included in the braille text print data. In the example described above, N is preferably 10.

The third print layer Ly3 is formed from the white ink on the second print layer Ly2. As is the second print layer Ly2, the third print layer Ly3 is glossy. Note, however, that as opposed to the second print layer Ly2, the third print layer Ly3 is formed in a single scan. For the thickness direction, the third print layer Ly3 is formed from a single shot of the white ink. The controller 30 moves the recording medium 5 downstream X2 over the length Lh per one iteration. The controller 30 intermittently repeats the operation described above, thus forming the third print layer Ly3.

Through the process described above, braille text including three print layers is formed on the recording medium 5. In the formed braille text, dots 101 in each cell 102 are formed so that the dot-to-dot spacing L1 (see FIG. 4) is preferably about 0.5 mm or more and about 1.2 mm or less, for example. The dimension has a tolerance of about 0.12 mm, for example. Therefore, with the dimension and the tolerance combined together, the dot-to-dot spacing L1 is preferably about 0.38 mm or more and about 0.62 mm or less, for example.

The height T of the dot 101 (see FIG. 5) is preferably about 0.55 mm or more and about 0.95 mm or less, for example. The height has a tolerance of about 0.095 mm. Therefore, with the dimension and the tolerance combined together, the height T of the dot 101 is preferably about 0.455 mm or more and about 1.045 mm or less, for example.

Moreover, the diameter D1 of the dot 101 (see FIG. 4 and FIG. 5) is preferably about 1.4 mm or more and about 1.7 mm or less, for example. The diameter has a tolerance of about 0.2 mm. Therefore, with the dimension and the tolerance combined together, the diameter D1 of the dot 101 is preferably about 1.2 mm or more and about 1.9 mm or less, for example.

The diameter D1 of the dot 101 may be greater than the pitch P1 of the nozzles 24 on the ink heads 21C to 21C1. The diameter D1 of the dot 101 is set by the print controller 31 based on the print data of the braille text 100. For example, when the pitch P1 is about 0.14 mm and the diameter D1 of the dot 101 is about 1.2 mm or more and about 1.9 mm or less, the diameter D1 of the dot 101 is greater than the pitch P1.

Letters 100 are formed so that the distance therebetween, i.e., the inter-cell spacing L2 (see FIG. 4), is preferably about 2.5 mm or more and about 5.0 mm or less. The inter-cell spacing L2 has a tolerance of about 0.2 mm. Therefore, with the dimension and the tolerance combined together, the inter-cell spacing L2 is preferably about 2.3 mm or more and about 5.2 mm or less, for example.

Each dot 101 of the braille text includes ink dots, each of which is smaller than the diameter D1 of the dot 101. The diameter of an ink dot upon landing is smaller than the diameter D1 of the dot 101. Since an ink dot is not necessarily circular, the diameter of an ink dot upon landing herein is an equivalent diameter that is obtained as the diameter of a circle whose area is equal or substantially equal to the area of the ink dot upon landing. The diameter of an ink dot upon landing is preferably about one half or less of the diameter D1 of the dot 101, for example. Alternatively, the diameter of an ink dot upon landing is one third or less of the diameter D1 of the dot 101. Settings may be changed so that the diameter of an ink dot upon landing is about one tenth or less of the diameter D1 of the dot 101. Conversely, each dot 101 of braille text is composed of a plurality of ink dots that are made when ink discharged from the ink discharge head 21 is cured.

The diameter of an ink dot upon landing is set by the size setter 32 of the controller 30. The diameter of an ink dot upon landing refers to the diameter of a photocurable ink droplet discharged from the ink heads 21C to 21C1 upon landing on the recording medium 5 or upon landing on photocurable ink on the recording medium 5. The diameter of an ink dot upon landing is preferably about 0.08 mm, for example. Herein, the size setter 32 sets the diameter of a photocurable ink droplet upon landing to be less than the diameter D1 of the dot 101. However, the diameter of an ink dot upon landing is not limited thereto. The diameter of an ink dot upon landing may vary depending on the print conditions. For example, for each set of print conditions, one or more ink dot size may be selected from among a plurality of predetermined ink dot sizes.

During the formation of the second print layer Ly2, the inkjet printer 10 according to the present preferred embodiment preferably feeds a length Lh/10 of the recording medium 5 per one iteration, wherein the feed length Lh/10 is set to be greater than the diameter D1 of the dot 101. In other words, a natural number N (N is a natural number of 2 or more) is preferably set such that Lh/N is greater than the diameter D1 of the dot 101, where the length Lh of the ink discharge head 21 is a predetermined length. N is the number of layers of the second print layer Ly2. In the present preferred embodiment, N is preferably 10, for example. It is understood that N may preferably be set to any other natural number that satisfies the conditions described above. For example, N may be set to 15, or other suitable values. FIG. 7 shows the relationship between the feed length Lh/N of the recording medium 5 (herein, N=10) and the arrangement of dots 101. As shown in FIG. 7, the feed length Lh/10 is greater than the diameter D1 of the dot 101. Note that the hatched portion of a dot 101 of FIG. 7 represents a portion of the dot 101 that has been formed at the time of FIG. 7.

As shown in FIG. 7, the feed length Lh/N during the formation of the second print layer Ly2 is set to be shorter than the dot-to-dot spacing L1 in the secondary scanning direction X. Moreover, the feed length Lh/N is shorter than the inter-cell spacing L2 in the secondary scanning direction X. And, the feed length Lh/N is shorter than the distance between a dot 101 in a cell 102 and a corresponding dot 101 in an adjacent cell 102, i.e., a pitch L3 of the cells 102 (see also FIG. 4), in the secondary scanning direction X. Thus, the length Lh/N is set so as to be greater than the diameter D1 of the dot 101 and less than the dot-to-dot spacing L1, the inter-cell spacing L2 and the cell pitch L3. Note, however, that this is one exemplary setting, which does not always need to be satisfied. Alternatively, only one or more of the diameter D1 of the dot 101, the dot-to-dot spacing L1, the inter-cell spacing L2, and the inter-cell pitch L3 may satisfy the above setting.

For example, the amount Lh/N by which the recording medium 5 is fed per one iteration when forming one print layer may be set to be greater than the dot-to-dot spacing L1 in the secondary scanning direction X. For example, when the length Lh is about 25.4 mm and the number of layers N is 16, for example, the feed amount Lh/N per one iteration is preferably about 1.59 mm, for example. This length is greater than the dot-to-dot spacing L1 (about 0.38 mm or more and about 0.62 mm or less, for example). Note, however, that the amount Lh/N by which the recording medium 5 is fed per one iteration when forming one print layer may be less than the dot-to-dot spacing L1 in the secondary scanning direction X. For example, when the length Lh is about 25.4 mm and the number of layers N is 96, the feed amount Lh/N per one iteration is preferably about 0.26 mm, for example. This length is less than the dot-to-dot spacing L1 (about 0.38 mm or more and about 0.62 mm or less, for example). The amount Lh/N by which the recording medium 5 is fed per one iteration may be greater than the inter-cell spacing L2 in the secondary scanning direction X. For example, when the length Lh is about 25.4 mm and the number of layers N is 4, the feed amount Lh/N per one iteration is preferably about 6.35 mm, for example. This length is greater than the inter-cell spacing L2 (about 2.3 mm or more and about 5.2 mm or less). The Lh/N by which the recording medium 5 is fed per one iteration may be greater than the diameter D1 of the dot 101. For example, when the length Lh is about 25.4 mm and the number of layers N is 8, the feed amount Lh/N per one iteration is preferably about 3.18 mm, for example. This length is greater than the diameter D1 of the dot 101 (about 1.2 mm or more and about 1.9 mm or less). Note, however, that the amount Lh/N by which the recording medium 5 is fed per one iteration may be less than the diameter D1 of the dot 101. For example, when the length Lh is about 25.4 mm and the number of layers N is 16, the feed amount Lh/N per one iteration is preferably about 1.59 mm, for example. This length may be less than the diameter D1 of the dot 101 (about 1.2 mm or more and about 1.9 mm or less).

The minimum landing spacing of photocurable ink in the primary scanning direction Y may be less than the diameter D1 of the dot 101. For example, when the minimum landing spacing of photocurable ink is about 0.07 mm, it is less than the diameter D1 of the dot 101 (about 1.2 mm or more and about 1.9 mm or less, for example). Moreover, the minimum landing spacing of photocurable ink in the primary scanning direction Y may be less than the dot-to-dot spacing L1. For example, when the minimum landing spacing of photocurable ink is about 0.07 mm, it is less than the dot-to-dot spacing L1 (about 0.38 mm or more and about 0.62 mm or less, for example).

Note that the number of print layers is preferably three, for example, in the method for forming braille text described above, but the number is not limited to three. The number of additional print layers to be formed over the first print layer may be one, for example. Then, the total number of print layers is two.

In the method for forming braille text described above, N-layer-stacking printing is performed when forming the second print layer Ly2, but the present invention is not limited thereto. The print layer for which layer-stacking printing is performed is not limited to the second print layer. The print layer for which layer-stacking printing is performed may be a print layer other than the second print layer or may be a plurality of print layers. No print layer may be formed by layer-stacking printing, and every print layer may be formed in a single scan. In any case, it is believed that eight is sufficient for the number of print layers. That is, the number of print layers may preferably be eight or less, and the number of additional print layers may preferably be seven or less, for example. Moreover, the type of ink used to form braille text is not limited to a clear ink and a white ink, but may include a color ink, for example. For example, preferably, in another preferred embodiment, preferably, the first print layer is a matte clear ink layer (single-layer), the second print layer is a glossy clear ink layer (multi-layer), and the third print layer is a color ink layer (single-layer). In still another preferred embodiment, preferably, the first print layer is a matte clear ink layer (single-layer), the second print layer is a glossy clear ink layer (multi-layer), the third print layer is a glossy clear ink layer (multi-layer), and the fourth print layer is a white ink layer (single-layer), for example. In yet another preferred embodiment, preferably the first print layer is a matte clear ink layer (single-layer), the second print layer is a glossy clear ink layer (multi-layer), the third print layer is a glossy clear ink layer (multi-layer), and the fourth print layer is a color ink layer (single-layer), for example. Moreover, one may employ any combination of the number, type and order of print layers.

Second Preferred Embodiment

In a second preferred embodiment of the present invention, the inkjet printer 10 forms a 3D print on the recording medium 5. FIG. 8 shows an exemplary 3D print formed by the inkjet printer 10 according to the present preferred embodiment. The 3D print shown in FIG. 8 is a 3D signage 110. The entirety of the 3D signage 110 shown in FIG. 8 is raised from the recording medium 5. Moreover, non-hatched portions are sunken relative to hatched portions. The 3D signage 110 represents a predetermined sign by the planar shape defined by boundaries between hatched portions and non-hatched portions. The boundaries are preferably rounded. The inkjet printer 10 according to the present preferred embodiment preferably forms a 3D print, such as the 3D signage 110 of FIG. 8, for example. There is no particular limitation on the type of ink used to form a 3D print, but a color ink and a clear ink are preferably used in the example to be discussed below.

FIG. 9 is a cross-sectional view of the 3D signage 110 taken along line IX-IX of FIG. 8. Note, however, that FIG. 9 is a schematic view, and may not necessarily represent the actual proportions of the various portions. As shown in FIG. 9, the 3D signage 110 includes four print layers. Of the four print layers, a first print layer Ly11 is formed directly on the recording medium 5. The first print layer Ly11 is the lowermost layer of the four print layers. The first print layer Ly11 is formed from the clear ink. A second print layer Ly12 is formed directly on the first print layer Ly11. The second print layer Ly12 is also formed from the clear ink. A third print layer Ly13 is formed directly on the second print layer Ly12. The third print layer Ly13 is also formed from the clear ink. A fourth print layer Ly14 is formed directly on the third print layer Ly13. The fourth print layer Ly14 is the uppermost layer of the four print layers. The fourth print layer Ly14 is formed from the color ink.

The first print layer Ly11 according to the present preferred embodiment is preferably a matte print layer of the clear ink, for example. In the formation of the first print layer Ly11, the controller 30 causes the clear ink to be discharged from the ink head 21C1 while moving the carriage 1 in the first primary scanning direction Y1, as in the first preferred embodiment. The controller 30 causes UV light to be output from the second UV lamp 25b to cure the discharged clear ink immediately. The inkjet printer 10 according to the present preferred embodiment forms the first print layer Ly11 by repeating the operation described above, as in the first preferred embodiment. After printing is completed for one scanning line, the recording medium 5 is moved downstream X2 over the length Lh, as in the first preferred embodiment. For the thickness direction, the first print layer Ly11 is formed from a single shot of the clear ink.

The second print layer Ly12 is formed on the first print layer Ly11. The second print layer Ly12 according to the present preferred embodiment is preferably a glossy print layer of the clear ink, for example. Between the formation of the first print layer Ly11 and the formation of the second print layer Ly12, the recording medium 5 is once returned to the upstream X1 side. Then, the second print layer Ly12 is formed on the first print layer Ly11. The controller 30 causes the clear ink to be discharged from the ink head 21C1 while moving the carriage 1 in the first primary scanning direction Y1, as in the first preferred embodiment. The discharged ink is cured by UV light output from the first UV lamp 25a while the carriage 1 is being returned in the second primary scanning direction Y2.

The controller 30 forms the second print layer Ly12 bit by bit while moving the recording medium 5 downstream X2 preferably over Lh/10 per one iteration, for example, as in the first preferred embodiment. The second print layer Ly12 is formed by a process similar to that used for forming the second print layer Ly2 in the first preferred embodiment. For the thickness direction, the second print layer Ly12 is formed from a plurality of shots of the clear ink. The second print layer Ly12 defines the relatively sunken portions of the upper surface of the 3D signage 110. In view of this, the second print layer Ly12 is preferably formed to be glossy with a smooth surface.

The third print layer Ly13 defines the relatively raised portions of the 3D signage 110. The third print layer Ly13 is also preferably a glossy print layer, for example. The third print layer Ly13 is formed in a plurality of scans, as is the second print layer Ly12. The boundary between the side surface and the upper surface of the third print layer Ly13 is rounded, as shown in FIG. 9. The roundedness is obtained by the stepped shape. In FIG. 9, the upper two layers of the third print layer Ly13 define the stepped shape. The edge portion E of FIG. 9 is where ink is not discharged during the formation of the upper two layers. The print data for the upper two layers is different from that for the other lower layers. During the formation of an actual 3D signage, every step portion sags down, thus forming a smooth curved surface. In the formation of the third print layer Ly13, it is possible to provide rounded corners as described above. Note that the “two layers” are merely illustrative, and it does not need to be two layers.

The fourth print layer Ly14 forms a color layer on the surface of the 3D signage 110. The fourth print layer Ly14 is formed from the color ink, giving a predetermined color or colors to the surface layer of the 3D signage 110 formed from the first print layer Ly11, the second print layer Ly12 and the third print layer Ly13. The fourth print layer is printed in a single scan.

Thus, with the inkjet printer 10 according to the present preferred embodiment, it is possible to effectively produce a 3D print. Note, however, that the method for producing a 3D signage using four print layers as described above is merely an example, and one may again use any combination of the number, type and order of print layers. For example, a clear ink (glossy) may be further formed as an overcoat on the color layer in order to give a glossy finish to the upper surface of the 3D signage. The shape of the 3D signage is also not limited to that shown in FIG. 8.

While preferred embodiments of the present invention have been described above, the present invention is not limited to the preferred embodiments above, and the present invention can be carried out in various other preferred embodiments.

For example, while the inkjet printer 10 according to the preferred embodiments described above prints while the carriage 1 is being moved in the first primary scanning direction Y1, it may also print while the carriage 1 is being moved in the second primary scanning direction Y2. That is, the inkjet printer 10 may perform two-way printing. When printing is performed while the carriage 1 is being moved in the second primary scanning direction Y2, UV light is output from the first UV lamp 25a during matte printing, and UV light is output from the second UV lamp 25b during gloss printing.

The inkjet printer 10 according to the preferred embodiments described above includes the carriage 1 that moves in the primary scanning direction Y, with the ink discharge head 21 mounted on the carriage 1. However, the carriage 1 may not be necessary. The inkjet printer may be a line-head inkjet printer in which the ink discharge head 21 does not move in the primary scanning direction Y. The inkjet printer may include ink discharge heads extending in the primary scanning direction Y and arranged next to each other in the secondary scanning direction X, and may be configured so that the recording medium is transported in the secondary scanning direction X. Alternatively, the inkjet printer may include ink discharge heads extending in the primary scanning direction Y and arranged next to each other in the secondary scanning direction X, and may be configured so that the ink discharge head moves in the secondary scanning direction X.

While the inkjet printer 10 according to the preferred embodiments described above continuously feeds the recording medium 5, it may alternatively be a “flat-bed” inkjet printer.

According to a method for forming braille text on a recording medium according to another preferred embodiment of the present invention, the braille text including a plurality of cells with one or more dots arranged in each cell, at least one of the cells including a plurality of dots arranged therein, the method includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging a photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer. Resultant braille text is formed by the print layer and the one or more additional print layer, and the resultant braille text preferably has an intra-cell dot-to-dot spacing of about 0.38 mm or more and about 1.32 mm or less, for example.

According to a method for forming braille text on a recording medium according to another preferred embodiment of the present invention, the braille text including a plurality of cells with one or more dots arranged in each cell, the method includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging a photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer. Resultant braille text is formed by the print layer and the one or more additional print layer, and the resultant braille text has preferably a dot diameter of about 1.2 mm or more and about 1.9 mm or less, for example.

According to a method for forming braille text on a recording medium according to another preferred embodiment of the present invention, the braille text including a plurality of dots, the method includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging a photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer, wherein resultant braille text is formed by the print layer and the one or more additional print layer, and ink dots of the photocurable ink upon landing preferably have a diameter that is about one half or less of a dot diameter of the resultant braille text, for example.

According to a method for forming braille text on a recording medium according to another preferred embodiment of the present invention, the braille text including a plurality of dots, the method includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging a photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer, wherein resultant braille text is formed by the print layer and the one or more additional print layer, and ink dots of the photocurable ink upon landing preferably have a diameter that is about one third or less of a dot diameter of the resultant braille text, for example.

According to a method for forming braille text on a recording medium according to another preferred embodiment of the present invention, the braille text including a plurality of cells with one or more dots arranged in each cell, the method includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging the photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer. The formation of at least one of the print layer and the one or more additional print layer includes a step of repeating the discharging and curing of the photocurable ink and an operation of moving the recording medium in a first direction over a first distance, wherein the first distance is preferably greater than a dot diameter of resultant braille text.

With the methods for forming braille text described above, it is possible to easily form braille text using a method for forming a plurality of print layers with a photocurable ink.

A method for forming a print on a recording medium according to a preferred embodiment of the present invention includes discharging the photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a first print layer on the recording medium, and discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a second print layer over the first print layer. The discharging and curing of the photocurable ink and an operation of moving the recording medium in a first direction are repeated a first number of iterations per a predetermined distance in the first direction, thus forming the first print layer, and the discharging and curing of the photocurable ink and an operation of moving the recording medium in the first direction are repeated a second number of iterations, different from the first number of iterations, per the predetermined distance in the first direction, thus forming the second print layer.

A method for forming a print on a recording medium according to a preferred embodiment of the present invention includes discharging a photocurable ink onto the recording medium and curing the discharged photocurable ink with light, thus forming a print layer on the recording medium, and discharging a photocurable ink onto the print layer and curing the discharged photocurable ink with light, thus forming one or more additional print layer on the print layer. The formation of at least one of the print layer and the one or more additional print layer includes a first step of discharging the photocurable ink onto a first area on the recording medium, a second step, after the first step, of moving the recording medium in a first direction, and a third step, after the second step, of discharging the photocurable ink onto a second area on the recording medium and further discharging the photocurable ink onto the first area, the second area being located in a second direction, which is opposite to the first direction, from the first area. Upon completion of the third step, a height of the first area is greater than a height of the second area.

With the methods for forming a print described above, it is possible to form a 3D signage using a method for forming a plurality of print layers with a photocurable ink. Regarding the formation of a plurality of print layers, by repeating the discharging and curing of the ink an intended number of iterations, it is possible to easily form a thick 3D signage.

The terms and expressions used herein are used for explanation purposes and should not be construed as being restrictive. It should be appreciated that the terms and expressions used herein do not eliminate any equivalents of features illustrated and mentioned herein, but include various modifications falling within the claimed scope of the present invention. The present invention may be embodied in many different forms. The present disclosure is to be considered as providing examples of the principles of the present invention. These examples are described herein with the understanding that such examples are not intended to limit the present invention to preferred embodiments described herein and/or illustrated herein. Hence, the present invention is not limited to the preferred embodiments described herein. The present invention includes any and all preferred embodiments including equivalent elements, modifications, omissions, combinations, adaptations and/or alterations as would be appreciated by those skilled in the art on the basis of the present disclosure. The limitations in the claims are to be interpreted broadly based on the language included in the claims and not limited to examples described in the present specification or during the prosecution of the application.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Number	Date	Country	Kind
2017-092895	May 2017	JP	national
2018-056874	Mar 2018	JP	national

METHOD FOR FORMING BRAILLE TEXT AND INKJET PRINTER

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