CN109195803B

CN109195803B - Data processing device, tablet printing device, data processing method, and tablet printing method

Info

Publication number: CN109195803B
Application number: CN201780033667.3A
Authority: CN
Inventors: 中野信行; 内田直树
Original assignee: Screen Holdings Co Ltd
Current assignee: Screen Holdings Co Ltd
Priority date: 2016-06-28
Filing date: 2017-06-26
Publication date: 2020-11-13
Anticipated expiration: 2037-06-26
Also published as: KR102176136B1; JP2018000282A; JP6811555B2; WO2018003742A1; CN109195803A; KR20190004746A

Abstract

A data processing device (80) of the present invention is a data processing device for creating print data (D5) for causing an ink jet type printing head to perform a printing process on the surface of a tablet. A data processing device (80) is provided with a vector rotation processing unit (81) and an image conversion processing unit (82). A vector rotation processing unit (81) performs vector rotation on input vector data (D1) and generates a plurality of vector rotation data (D2) corresponding to a plurality of rotation angles. An image conversion processing unit (82) converts each of the vector rotation data (D2) in the vector rotation data (D2) into raster data (D3). This can suppress the degradation of image quality due to the rotation of the image. As a result, the occurrence of a decrease in the print quality of the tablet printing apparatus can be suppressed. Therefore, the printing quality of the ink jet tablet printing apparatus can be improved.

Description

Data processing device, tablet printing device, data processing method, and tablet printing method

Technical Field

The present invention relates to a data processing device and a data processing method for creating print data used in a tablet printing device for printing on a surface of a tablet, and a tablet printing device and a tablet printing method.

Background

The surface of a tablet as a medicine is printed with a letter or a number for identifying the product. Such letters or numbers are sometimes printed by imprinting. However, the imprint has a problem of low recognizability. In particular, in recent years, the popularization of general-purpose medicines has diversified the kinds of tablets. Therefore, in order to accurately identify the tablet, it is desirable to clearly print the surface of the tablet.

In recent years, orally disintegrating tablets which can be taken without using water have become widespread. The orally disintegrating tablets have a weak resistance to pressure. Therefore, when the orally disintegrating tablet is printed, it is preferable to print without applying pressure. Therefore, a technique of printing an image on the surface of a tablet by an ink jet method is attracting attention. The ink jet tablet printing apparatus can print an image clearer than an imprint on the surface of a tablet. Further, the image can be printed in a non-contact manner without applying pressure to the surface of the tablet.

In recent years, a dividing line piece that can be divided along a dividing line has become popular. When printing tablets having directionality such as cut line tablets or capsule tablets, it is necessary to print a plurality of tablets to be conveyed in a direction matching the orientation of each tablet. A conventional tablet printing apparatus of an inkjet system that performs printing in consideration of the orientation of tablets is described in patent document 1, for example.

Documents of the prior art

Patent document 1: japanese laid-open patent publication (JP 2015-223323)

Disclosure of Invention

Problems to be solved by the invention

In an ink jet tablet printer, an image is displayed by arranging dots in a vertical and horizontal grid pattern. Therefore, in the tablet printing apparatus of the ink jet system, an image is formed on the surface of the tablet by using print data in which whether or not ink droplets are ejected in each region arranged in a lattice shape on the surface of the tablet and the size of the ink droplets are selected.

In such an ink jet type tablet printer, when the print image is rotated in consideration of the orientation of the tablet, even if only the basic print data is rotated, the ink droplet ejection position in the print data may not coincide with the area where the ink droplet can be ejected by the ink jet print head. Therefore, if the print data obtained by rotating only the basic print data is used, the print quality may be degraded as compared with the case of using the print data without rotation.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for improving the print quality of an ink jet tablet printer.

Technical scheme for solving problems

In order to solve the above problem, the invention of claim 1 is a data processing device for creating print data for performing a print process on a surface of a tablet by an inkjet print head, the data processing device including: the image processing apparatus includes a vector rotation processing unit that performs vector rotation on input vector data and generates a plurality of vector rotation data corresponding to a plurality of rotation angles, and an image conversion processing unit that converts each of the vector rotation data into raster data.

The 2 nd aspect of the present application is the data processing device according to the 1 st aspect, wherein the data processing device further includes a thinning-out processing unit that converts each of a plurality of the raster data, which is data in which an ink ejection amount is set for each of regions arranged in a lattice shape, into thinned-out data in which the number of ink ejection pixels is smaller than that of the raster data, and the ink ejection region from which ink is ejected in the thinned-out data is smaller than that in the raster data.

The 3 rd aspect of the present application is the data processing apparatus according to the 2 nd aspect of the present application, wherein the thinning-out processing unit generates the thinned-out data by converting a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and non-ink ejection regions are alternately arranged.

In the data processing device according to claim 4 of the present application, in the thinning unit, a portion of the raster data where the ink discharge regions are continuous is converted into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged, and the thinning data is generated.

The 5 th aspect of the present invention is a tablet printing apparatus that prints on a surface of a tablet, the tablet printing apparatus including: a data processing device for creating print data, an ink jet type printing head having a plurality of nozzles for ejecting ink droplets and ejecting the ink droplets to the surface of the tablet to perform a printing process, a camera disposed upstream of the printing head for detecting a rotation angle of the tablet, and a control unit for controlling the ejection of the ink droplets from the printing head; the data processing apparatus has: a vector rotation processing unit that performs vector rotation on input vector data and generates a plurality of vector rotation data corresponding to a plurality of rotation angles, and an image conversion processing unit that converts each of the vector rotation data into raster data, the data processing device outputting a plurality of print data based on the plurality of raster data; the control unit includes: a print data holding unit that holds a plurality of print data corresponding to the rotation angle, and a print processing unit that selects the print data from the print data holding unit based on the rotation angle detected by the camera and causes the print head to perform print processing based on the selected print data; the print data holding unit holds the plurality of print data input from the data processing device before the rotation angle is detected by the camera.

The 6 th aspect of the present application is the tablet printing apparatus according to the 5 th aspect of the present application, wherein the data processing apparatus further includes a thinning-out processing unit that converts each of a plurality of the raster data, which is data in which an ink ejection amount is set for each of regions arranged in a lattice shape, into thinned-out data in which an ink ejection region from which ink is ejected is smaller than the ink ejection region in the raster data, into a smaller number of ink ejection pixels than the raster data, the data processing apparatus outputs the plurality of the thinned-out data as the print data, and the print data holding unit holds the plurality of the print data input from the data processing apparatus until the rotation angle is detected by the camera.

In the tablet printing apparatus according to claim 7 of the present application, the thinning-out processing unit generates the thinned-out data by converting a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and non-ink ejection regions are alternately arranged.

In the tablet printing apparatus according to claim 8 of the present application, in the thinning unit, a portion of the raster data where the ink discharge regions are continuous is converted into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged, and the thinning data is generated.

The 9 th aspect of the present invention is a data processing method for creating print data for performing a printing process on a surface of a tablet by an inkjet printing head, the data processing method including: a) a step of vector-rotating the input vector data and generating a plurality of vector-rotated data corresponding to the plurality of rotation angles, and b) a step of converting each of the plurality of vector-rotated data into raster data.

A 10 th aspect of the present application is the data processing method according to the 9 th aspect, wherein the data processing method further includes a c) step of converting each of the plurality of raster data into thinned data having fewer ink ejection pixels than the raster data, the raster data being data in which an ink ejection amount is set for each of regions arranged in a lattice shape, and an ink ejection region from which ink is ejected in the thinned data being smaller than the ink ejection region in the raster data.

The 11 th aspect of the present application is the data processing method according to the 10 th aspect of the present application, wherein in the c) step, the thinned-out data is generated by converting a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and non-ink ejection regions are alternately arranged.

The 12 th aspect of the present application is the data processing method according to the 11 th aspect of the present application, wherein in the c) step, the thinned-out data is generated by converting a portion of the raster data in which the ink ejection regions are continuous into a pattern in which the ink ejection regions having a quadrangular shape and the non-ink ejection regions having a quadrangular shape are alternately arranged.

The 13 th invention of the present application is a tablet printing method for performing a printing process on a surface of a tablet by an inkjet printing head, wherein the tablet printing method comprises: A) a step of performing vector rotation on input vector data and generating a plurality of vector rotation data corresponding to a plurality of rotation angles, a) a step of converting each of the plurality of vector rotation data into raster data, a C) a step of retaining a plurality of print data corresponding to the rotation angle based on the raster data obtained in the step B), a D) a step of detecting the rotation angle of the tablet after the C) a step of selecting the print data to be used for a printing process from the plurality of print data based on the rotation angle after the D) a step of printing an image on a surface of the tablet based on the print data selected in the step E).

A 14 th aspect of the present invention is the tablet printing method according to the 13 th aspect, wherein the tablet printing method further includes a step G) of converting each of the plurality of raster data into thinned data having a smaller number of ink ejection pixels than the raster data after the step B) and before the step C), and in the step C), the plurality of thinned data is held as the plurality of print data, the raster data is data in which an ink ejection amount is set for each of regions arranged in a lattice shape, and an ink ejection region of the ejected ink in the thinned data is smaller than the ink ejection region in the raster data.

In the 15 th aspect of the present application, in the tablet printing method according to the 14 th aspect, in the step G), the thinned data is generated by converting a portion of the raster data in which the ink ejection regions are continuous into a pattern in which the ink ejection regions and non-ink ejection regions are alternately arranged.

The 16 th aspect of the present application is the tablet printing method according to the 15 th aspect of the present application, wherein in the step G), the thinned data is generated by converting a portion of the raster data in which the ink discharge regions are continuous into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged.

Effects of the invention

According to the invention 1 to 16 of the present application, raster data obtained by rasterizing vector data subjected to vector rotation in advance is used as print data. This can suppress the degradation of image quality due to the rotation of the image. As a result, the occurrence of a decrease in the print quality of the tablet printing apparatus can be suppressed.

According to the inventions 2 to 4, 6 to 8, 10 to 12, and 14 to 16 of the present application, it is possible to suppress occurrence of unevenness when a tablet printing apparatus performs a printing process. Therefore, the occurrence of a decrease in the print quality of the tablet printing apparatus can be further suppressed.

Drawings

Fig. 1 is a diagram showing the structure of a tablet printing apparatus.

Fig. 2 is a perspective view of the vicinity of the conveying roller.

Fig. 3 is a bottom view of the print head.

Fig. 4 is a block diagram showing the connection of the control unit to each unit and the data processing device in the tablet printing apparatus.

Fig. 5 is a block diagram conceptually showing a configuration related to the printing process corresponding to the rotation angle in the tablet printing apparatus and the data processing apparatus 80.

Fig. 6 is a flowchart showing a flow of data processing in the data processing apparatus.

Fig. 7 is a diagram showing an example of rasterizing vector data without rotation.

Fig. 8 is a diagram showing an example in which vector data is rotated after being rasterized, and then is rasterized again.

Fig. 9 is a diagram showing an example of rasterizing vector data after vector rotation.

Fig. 10 is a conceptual diagram illustrating a state in which ink droplets are ejected to a portion where the ejection area is continuous.

Fig. 11 is a conceptual diagram illustrating a state in which ink droplets are ejected to a portion where the ejection area is continuous.

Fig. 12 is a conceptual diagram illustrating a state in which ink droplets are ejected to a portion where the ejection area is continuous.

Fig. 13 is a graph showing a relationship between the droplet size and the pattern transfer speed and the occurrence state of Mottling (Mottling) in the experiment.

Fig. 14 is a diagram illustrating an example of the sparse pattern.

Fig. 15 is a diagram showing an example of sparse data using the sparse pattern shown in fig. 14.

Fig. 16 is a diagram illustrating an example of the sparse pattern.

Fig. 17 is a diagram showing an example of sparse data using the sparse pattern shown in fig. 16.

Fig. 18 is a diagram illustrating an example of the sparse pattern.

Fig. 19 is a diagram showing an example of sparse data using the sparse pattern shown in fig. 18.

Fig. 20 is a diagram illustrating an example of the sparse pattern.

Fig. 21 is a flowchart showing a flow of a printing process in the tablet printing apparatus.

Fig. 22 is a diagram illustrating an example of print data stored in the print data holding unit.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. In the following description, a direction in which a plurality of tablets are conveyed is referred to as a "conveying direction", and a direction perpendicular to and horizontal to the conveying direction is referred to as a "width direction".

1. Structure of tablet printing device

Fig. 1 is a diagram showing a configuration of a tablet printing apparatus 1 according to an embodiment of the present invention. The tablet printing apparatus 1 is an apparatus that prints images such as a product name, a product number, a company name, and a logo on the surface of each tablet 9 while conveying a plurality of tablets 9 as a medicine. As shown in fig. 1, the tablet printing apparatus 1 of the present embodiment includes a hopper 10, a feeder 20, a transport cylinder 30, a first printing unit 40, a second printing unit 50, a carry-out conveyor 60, and a control unit 70.

The hopper 10 is a loading section for receiving a large number of tablets 9 into the apparatus together. The hopper 10 is disposed at the uppermost portion of the housing 100 of the tablet printing apparatus 1. The hopper 10 has an opening 11 located on the upper surface of the casing 100 and a funnel-shaped inclined surface 12 converging downward. The plurality of tablets 9 fed into the opening 11 flow into the straight feeder 21 along the inclined surface 12.

The feeder unit 20 conveys the plurality of tablets 9 loaded into the hopper 10 to the conveying drum 30. The feeder unit 20 of the present embodiment includes a straight feeder 21, a rotary feeder 22, and an inclined feeder 23. The linear feeder 21 has a plate-shaped vibration groove 211. The plurality of tablets 9 supplied from the hopper 10 to the vibration tank 211 are conveyed to the rotary feeder 22 side by the vibration of the vibration tank 211. The rotary feeder 22 includes a disk-shaped rotary table 221. The plurality of tablets 9 falling from the vibration groove 211 onto the upper surface of the rotary table 221 are gathered near the outer periphery of the rotary table 221 by the centrifugal force generated by the rotation of the rotary table 221.

The inclined feeder 23 has a plate-like slope 231 extending obliquely downward from the outer periphery of the rotating table 221 to the conveying roller 30. Fig. 2 is a perspective view of the vicinity of the conveying roller 30. As shown in fig. 2, a plurality of conveyance grooves 232 are provided on the upper surface of the slope 231. In the example of fig. 2, 8 conveyance grooves 232 are provided on the upper surface of the slope 231. The plurality of tablets 9 conveyed to the outer periphery of the rotary table 221 are supplied to any one of the conveying grooves 232, and slide down obliquely along the conveying groove 232. In this way, the plurality of tablets 9 are supplied to the plurality of conveying grooves 232 in a dispersed manner, and are thereby arranged in a plurality of conveying lines. Then, the plurality of tablets 9 of each conveying line are sequentially supplied to the conveying drum 30 from the leading tablet.

The conveying drum 30 is a mechanism for transferring the plurality of tablets 9 from the inclined feeder 23 to the first conveying belt 41. The conveying roller 30 has a substantially cylindrical outer peripheral surface. The conveying roller 30 is rotated in the direction of the arrow in fig. 1 and 2 around a rotation shaft extending in the width direction by power obtained from a motor, not shown. As shown in fig. 2, a plurality of suction holes 31 are provided in the outer circumferential surface of the conveying roller 30. The plurality of suction holes 31 are arranged in the circumferential direction on the outer circumferential surface of the conveying drum 30 at the widthwise positions corresponding to the plurality of conveying lines.

A suction mechanism, not shown, is provided inside the conveying roller 30. When the suction mechanism is operated, a negative pressure lower than the atmospheric pressure is generated in each of the plurality of suction holes 31. The suction holes 31 suck and hold the tablets 9 supplied from the inclined feeder 23 one by the negative pressure. An air supply mechanism, not shown, is provided inside the conveying drum 30. The air supply mechanism locally blows pressurized gas from the inner side of the transport drum 30 to the first transport conveyor 41 described later. Thus, the adsorption of the tablets 9 is released only on the adsorption holes 31 facing the first conveying belt 41 while maintaining the adsorption state of the tablets 9 on the adsorption holes 31 not facing the first conveying belt 41. The conveying drum 30 can rotate while holding the plurality of tablets 9 supplied from the inclined feeder 23 by suction in this manner, and can transfer the tablets 9 to the first conveying belt 41.

The conveying drum 30 has a first secant detection camera 32 on its outer periphery. The first dividing line detection camera 32 is an imaging unit that images the state of the tablet 9 before printing. The first split line detection camera 32 takes an image of the tablet 9 conveyed by the conveying drum 30, and sends the obtained image to the control section 70. The controller 70 detects the presence or absence of the tablet 9 in each suction hole 31 or the front and back surfaces and the rotation angle of the tablet 9 held by the suction hole 31 based on the received image.

The first printing unit 40 is a processing unit for printing an image on one surface of the tablet 9. As shown in fig. 1, the first printing unit 40 includes a first conveyance belt 41, a second cut line detection camera 42, a first print head unit 43, a first inspection camera 44, and a first fixing unit 45.

The first conveyance belt 41 is a conveyance mechanism including a pair of pulleys 411 and an endless conveyance belt 412 stretched between the pair of pulleys 411. The conveyor belt 412 is disposed so that a part thereof is close to and faces the outer peripheral surface of the conveyor roller 30. One of the pair of pulleys 411 is rotated by power obtained from a motor, not shown. Thereby, the conveying belt 412 rotates in the arrow direction of fig. 1 and 2. At this time, the other of the pair of pulleys 411 is driven to rotate in accordance with the rotation of the conveyor belt 412.

As shown in fig. 2, the conveyance belt 412 is provided with a plurality of suction holes 413. The plurality of suction holes 413 are arranged along the conveyance direction at a widthwise position corresponding to each of the plurality of conveyance lines. That is, the plurality of suction holes 413 are arranged at intervals in the width direction and the conveyance direction. The intervals in the width direction of the plurality of suction holes 413 on the conveyor belt 412 are equal to the intervals in the width direction of the plurality of suction holes 31 on the conveyor roller 30.

The conveyance belt 412 is provided with a suction mechanism, not shown. When the suction mechanism is operated, a negative pressure lower than the atmospheric pressure is generated in each of the plurality of adsorption holes 413. The suction holes 413 suck and hold the tablets 9 transferred from the transport drum 30 one by the negative pressure. Thus, the first conveying belt 41 conveys the plurality of tablets 9 while holding the plurality of tablets 9 in a state where the plurality of tablets 9 are arranged in a plurality of conveying lines spaced apart in the width direction. The conveying belt 412 is provided with an air supply mechanism, not shown. When the air supply mechanism is operated, the air pressure of the suction holes 413 facing the second conveyance belt 51 described later becomes a positive pressure higher than the atmospheric pressure. Thereby, the adsorption of the tablet 9 by the adsorption holes 413 is released, and the tablet 9 is transferred from the first conveying belt 41 to the second conveying belt 51.

The second dividing line detection camera 42 is an imaging unit that images the state of the tablet 9 before printing on the upstream side in the conveyance direction of the first print head unit 43. The second split line detection camera 42 captures an image of the tablet 9 conveyed by the first conveying conveyor 41, and sends the obtained image to the control section 70. Based on the received image, the control unit 70 detects the presence or absence of the tablet 9 in each suction hole 413, or the front and back surfaces and the rotation angle of the tablet 9 held by the suction hole 413.

The first print head unit 43 is an ink jet type print head unit that ejects ink droplets onto the surface of the tablet 9 conveyed by the first conveying conveyor 41. The first print head unit 43 has four print heads 431 arranged in the conveyance direction. The four print heads 431 eject ink droplets of different colors (for example, cyan, magenta, yellow, and black colors) onto the surface of the tablet 9. By superimposing monochromatic images formed by these respective colors, a multicolor image is recorded on the surface of the tablet 9. As the ink discharged from each of the printing heads 431, an edible ink manufactured from a material approved by the food sanitation law is used.

Fig. 3 is a bottom view of a print head 431. Fig. 3 shows the conveying belt 412 and the plurality of tablets 9 held by the conveying belt 412 by two-dot chain lines. As enlarged in fig. 3, a plurality of nozzles 430 capable of ejecting ink droplets are provided on the lower surface of the print head 431. In the present embodiment, a plurality of nozzles 430 are two-dimensionally arranged in the conveyance direction and the width direction on the lower surface of the print head 431. The nozzles 430 are arranged at positions shifted in the width direction. That is, the plurality of nozzles 430 are arranged at different positions from each other in the width direction. Thus, when the plurality of nozzles 430 are arranged two-dimensionally, the positions of the nozzles 430 in the width direction can be made close to each other. However, the plurality of nozzles 430 may be aligned in a row in the width direction.

For example, a piezoelectric method is used as an ejection method for ejecting ink droplets from the nozzles 430, and the piezoelectric method is a method in which a voltage is applied to a piezoelectric element, which is a piezoelectric element, to deform the piezoelectric element, thereby pressurizing ink in the nozzles 430 and ejecting the ink. The print head 431 of the present embodiment can switch the size of the ink droplet ejected from the nozzle 430 according to the magnitude of the voltage applied to the piezoelectric element. Specifically, any of three ink droplets, i.e., "small size" which is the smallest minute ink droplet, the "large size" which is the largest ink droplet, and the "medium size" which is the intermediate ink droplet, can be ejected. However, the size of the ink droplets that can be ejected may be one to two, or four or more. The ink droplet ejection method may be a method of ejecting ink by heating and expanding ink in the nozzle 430 by energizing a heater, that is, a so-called heating method.

Returning to fig. 1. The first inspection camera 44 is an imaging unit for confirming a printing result of the first print head unit 43. The first inspection camera 44 images the surfaces of the plurality of tablets 9 conveyed by the first conveyance conveyer 41 on the downstream side in the conveyance direction of the first print head unit 43, and sends the obtained image data to the control section 70. The control unit 70 determines whether or not there is a print defect such as a positional deviation or dot missing in the image printed on the surface of each tablet 9 based on the received image data.

The first fixing unit 45 is a mechanism for fixing the ink discharged from the first print head unit 43 to the tablet 9. In the present embodiment, the first fixing unit 45 is disposed on the downstream side in the conveyance direction of the first inspection camera 44. However, the first fixing unit 45 may be disposed between the first print head unit 43 and the first inspection camera 44. As the first fixing section 45, for example, a hot air drying heater that blows hot air to the tablet 9 conveyed by the first conveying conveyor 41 is used. The ink adhering to the surface of tablet 9 is dried by hot air, and thereby fixed on the surface of tablet 9.

The second printing unit 50 is a processing unit for printing an image on the other surface of the tablet 9 after the printing by the first printing unit 40. As shown in fig. 1, the second printing section 50 includes a second transport conveyor 51, a third cut line detection camera 52, a second print head unit 53, a second inspection camera 54, and a second fixing section 55. The second conveying conveyor 51 conveys the plurality of tablets 9 while holding the plurality of tablets 9 conveyed from the first conveying conveyor 41. The third split line detection camera 52 images the plurality of tablets 9 conveyed by the second conveyance conveyer 51 on the upstream side in the conveyance direction of the second print head unit 53. The second printing head unit 53 ejects ink onto the surface of the tablet 9 conveyed by the second conveying conveyor 51. The second inspection camera 54 images the surfaces of the plurality of tablets 9 conveyed by the second conveyance conveyer 51 on the downstream side in the conveyance direction of the second print head unit 53. The second fixing section 55 fixes the ink discharged from each print head 531 of the second print head unit 53 to the tablet 9.

The specific configuration of each of the second conveyance belt 51, the third split line detection camera 52, the second print head unit 53, the second inspection camera 54, and the second fixing section 55 is the same as that of the first conveyance belt 41, the second split line detection camera 42, the first print head unit 43, the first inspection camera 44, and the first fixing section 45, and therefore, a repetitive description thereof will be omitted.

The carrying-out conveyor 60 is a mechanism for carrying out the plurality of printed tablets 9 to the outside of the casing 100 of the tablet printing apparatus 1. The upstream end of the discharge conveyor 60 is located below the second conveyance conveyor 51. The downstream end of the discharge conveyor 60 is located outside the casing 100. For example, a belt conveying mechanism is used as the carry-out conveyor 60. After the printing process in the second printing section 50, the plurality of tablets 9 are sucked through the suction holes and fall from the upper surface of the carry-out conveyor 60 of the second conveying conveyor 51. Then, the plurality of tablets 9 are carried out to the outside of the casing 100 by the carrying-out conveyor 60.

The control unit 70 controls the operation of each unit in the tablet printing apparatus 1. Fig. 4 is a block diagram showing the connection of the control unit 70 to each unit in the tablet printing apparatus 1. As conceptually shown in fig. 1, the control unit 70 is constituted by a computer having an arithmetic processing unit 701 such as a CPU, a memory 702 such as a RAM, and a storage unit 703 such as a hard disk drive. A computer program P for executing a printing process is installed in the storage unit 703.

As shown in fig. 4, the control unit 70 is connected to the above-described straight feeder 21, rotary feeder 22, conveying drum 30 (including a motor, a suction mechanism, and an air supply mechanism), first cut line detection camera 32, first conveying conveyor 41 (including a motor, a suction mechanism, and an air supply mechanism), second cut line detection camera 42, first print head unit 43 (including a plurality of nozzles 430 of each print head 431), first inspection camera 44, first fixing unit 45, second conveying conveyor 51, third cut line detection camera 52, second print head unit 53 (including a plurality of nozzles of each print head 531), second inspection camera 54, second fixing unit 55, and carrying-out conveyor 60 so as to be able to communicate with each other. The control unit 70 is connected to the data processing device 80 so as to be able to communicate with it.

The control unit 70 controls the operations of the above-described respective units by temporarily reading the computer program P and the data D stored in the storage unit 703 into the memory 702 and causing the arithmetic processing unit 701 to perform arithmetic processing based on the computer program P. Thereby, the plurality of tablets 9 are subjected to the printing process.

The data processing device 80 processes the print data input to the tablet printing device 1. As conceptually shown in fig. 1, the data processing device 80 is constituted by a computer having an arithmetic processing unit 801 such as a CPU, a memory 802 such as a RAM, and a storage unit 803 such as a hard disk drive. A computer program Pd for executing data processing is installed in the storage unit 803.

The data processing device 80 temporarily reads the computer program Pd and the data Dd stored in the storage unit 803 into the memory 802, and causes the arithmetic processing unit 801 to perform arithmetic processing and data processing to be described later based on the computer program Pd. Thereby, data processing for creating print data is performed.

2. Data processing apparatus and control unit structure

Next, specific configurations of the data processing device 80 and the control unit 70 of the tablet printing device 1 will be described. The control unit 70 of the tablet printing apparatus 1 receives print data D5 created by the data processing device 80. The tablet printing apparatus 1 performs the printing process of the tablet 9 corresponding to the rotation angle based on the print data D5. Fig. 5 is a block diagram conceptually showing a configuration related to the printing process according to the rotation angle of the tablet printing apparatus 1 and the data processing apparatus 80.

As shown in fig. 5, the data processing device 80 of the present embodiment includes a vector rotation processing unit 81, an image conversion processing unit 82, and a thinning-out processing unit 83. The respective functions of the vector rotation processing unit 81, the image conversion processing unit 82, and the thinning-out processing unit 83 are realized by the computer as the data processing device 80 operating according to the above-described computer program Pd.

Input data D1, which is vector data representing an image to be printed, is input to the vector rotation processing unit 81 from the outside. The vector rotation processing unit 81 vector-rotates the input data D1 to a predetermined plurality of rotation angles. Thus, the vector rotation processing unit 81 generates a plurality of vector rotation data D2 corresponding to a plurality of rotation angles.

The vector rotation processing unit 81 of the present embodiment vector-rotates the input data D1 at 2 ° intervals to generate vector rotation data D2. That is, the vector rotation processing unit 81 generates 180 pieces of vector rotation data D2 of rotation angle 0 ° (no rotation), 2 °, 4 °, 6 °, …, and 358 °. In addition, the rotation angle at which the vector rotation data D2 is generated is not limited to every 2 °. The rotation angle at which the vector rotation data D2 is generated may be every 1 °, every 1.5 °, every 3 °, or every other angle.

The image conversion processing section 82 rasterizes each of the plurality of vector rotation data D2 generated by the vector rotation processing section 81, vector rotation data D2, and converts into raster data D3. Thereby, a plurality of raster data D3 corresponding to a plurality of rotation angles is generated. The raster data D3 is data for setting the ink ejection amount for each of the regions arranged in a grid.

The thinning-out processing section 83 converts each of the plurality of raster data D3 generated by the image conversion processing section 82 into the thinned-out data D4. Thereby, a plurality of sparse data D4 corresponding to a plurality of rotation angles are generated. The thinned data D4 is raster data in which the number of pixels from which ink is ejected (hereinafter referred to as "the number of ink ejected pixels") is smaller than the raster data D3. That is, the ink ejection region (hereinafter referred to as "ink ejection region") in the thinned data D4 is smaller than the ink ejection region in the raster data D3.

The data processing device 80 of the present embodiment outputs the plurality of thinned-out data D4 generated by the thinning-out unit 83 to the control unit 70 of the tablet printing apparatus 1 as the plurality of print data D5. However, the present invention is not limited thereto. The plurality of print data D5 output to the control unit 70 may be data based on the plurality of raster data D3. For example, the data processing apparatus of the present invention may not have the inter-thinning processing unit 83. In this case, the data processing device 80 outputs the raster data D3 generated by the image conversion processing unit 82 to the control unit 70 of the tablet printing device 1 as the print data D5.

Further, as in the tablet printing apparatus 1 of the present embodiment, when performing printing processing on both the front surface and the back surface of the tablet 9, the data processing device 80 needs to generate two data of the front surface printing data D5 and the back surface printing data D5 in advance.

The control unit 70 of the present embodiment includes a print data holding unit 71, a rotation angle detection unit 72, a print data selection unit 73, and an ejection control unit 74. The function of the print data holding unit 71 is realized by the above-described memory unit 703. The respective functions of the rotation angle detecting unit 72, the print data selecting unit 73, and the ejection control unit 74 are realized by the computer as the control unit 70 operating according to the computer program P described above.

The print data holding unit 71 holds the plurality of thinned-out data D4 input from the data processing device 80 as a plurality of print data D5. When the plurality of raster data D3 is input as the plurality of print data D5 from the data processing device 80, the print data holding unit 71 holds the plurality of raster data D3 as the plurality of print data D5.

The rotation angle detecting unit 72 detects the presence, front, back, and rotation angle of the tablet 9 held in each suction hole 413 of the first conveying belt 41 based on the image data D6 of the tablet 9 input from the first and second split

line detection cameras

32 and 42. The rotation angle detecting unit 72 detects the presence, front, back, and rotation angle of the tablet 9 held in each suction hole of the second conveying belt 51 based on the image data D6 of the tablet 9 input from the first cut line detecting camera 32, the second cut line detecting camera 42, and the third cut line detecting camera 52.

The print data selecting section 73 selects the print data D5 to be printed on each tablet 9 from the plurality of print data D5 held by the print data holding section 71 based on the detection result D7 of the rotation angle detecting section 72, and transmits the print data to the ejection control section 74.

The ejection control unit 74 controls the ejection of ink from the nozzles of the first print head unit 43 and the second print head unit 53 based on the print data D5 received from the print data selection unit 73, and ejects ink onto the surface of each tablet 9.

3. Flow of data processing in a data processing apparatus

Next, the flow of the printing process according to the rotation angle in the data processing device 80 and the tablet printing device 1 will be described with reference to fig. 6. Fig. 6 is a flowchart showing a flow of data processing in the data processing device 80. Before the printing process of the tablet printing apparatus 1 described later, the data processing of the data processing apparatus 80 shown in fig. 6 is performed.

As shown in fig. 6, in the data processing of the data processing device 80, first, input data D1 as vector data is input to the vector rotation processing unit 81 (step S101).

Next, the vector rotation processing unit 81 vector-rotates the input data D1 to a predetermined plurality of rotation angles to generate a plurality of vector rotation data D2 (step S102).

Next, the image conversion processing section 82 rasterizes each of the plurality of vector rotation data D2 from the plurality of vector rotation data D2, and generates a plurality of raster data D3 (step S103).

Here, the order of rotation and rasterization of vector data will be described with reference to the examples of fig. 7 to 9. Fig. 7 is a diagram showing an example of rasterizing vector data without rotation. Fig. 8 is a diagram showing an example in which vector data is rasterized, rotated, and then rasterized again. Fig. 9 is a diagram showing an example in which vector data is vector-rotated and then rasterized. In fig. 7 to 9, the data is rasterized into binary data.

The tablet printer 1 as an ink jet printer ejects ink droplets from the ink jet type printing heads 431 and 531 to each of the ink ejection areas arranged in a vertically and horizontally lattice shape. Thereby, one droplet is ejected for each ink ejection area. Therefore, in the printing process in the tablet printing apparatus 1, it is necessary to prepare print data in which the presence or absence of ink droplets and the size of the ink droplets are specified for each ink ejection area. Therefore, it is necessary to convert the input vector data into raster data which is expressed for each pixel arranged in a horizontal and vertical grid pattern.

As shown in fig. 7, when the rotation angle is 0 ° (no rotation), since it is not necessary to rotate the image data, it is possible to use raster data obtained by rasterizing only vector data as printing data.

When the rotation angle is not 0 °, it is necessary to rotate the image data at any timing and prepare raster data rasterized in a predetermined direction as final printing data.

As shown in fig. 8, when the first raster data obtained by rasterizing the vector data is rotated to generate raster rotation data, each pixel of the raster rotation data is arranged in a grid shape inclined with respect to the vertical and horizontal directions. Therefore, the raster rotation data cannot be used as the printing data. Therefore, in order to convert the raster rotation data into pixel data in the vertical and horizontal directions, rasterization needs to be performed again. The second raster data obtained by the re-rasterization has a greater jitter than the raster data obtained when the rotation angle is 0 ° (no rotation). Therefore, if printing is performed using the second raster data, there is a possibility that the printing quality may be degraded.

Therefore, as shown in fig. 9, the data processing device 80 of the present embodiment generates raster data by rasterizing vector rotation data obtained by vector-rotating vector data. This makes it possible to obtain raster data having the same quality as when the rotation angle is 0 ° (no rotation). Therefore, the degradation of the print quality is suppressed.

When the print quality is degraded due to the rotation, a strict threshold value cannot be used when the

inspection cameras

44 and 54 inspect the print result. In this way, if the degradation of the print quality due to the rotation is suppressed, a strict threshold value can be used when the

inspection camera

44 or 54 inspects the print result. Therefore, the degradation of the print quality can be further suppressed.

After the image conversion processing section 82 has generated the plurality of raster data D3 in step S103, the thinning-out processing section 83 converts each of the raster data D3 of the plurality of raster data D3 to generate a plurality of thinned-out data D4 (step S104). Then, the thinned-out data D4 is output to the control unit 70 of the tablet printing apparatus 1 as print data D5 (step S105).

Here, the conversion process performed by the thinning-out processing unit 83 will be described with reference to fig. 10 to 21. Fig. 10 to 12 are conceptual diagrams illustrating a state in which ink droplets are ejected to a portion where the ejection area of the raster data D3 is continuous. Fig. 10 is a diagram showing an example of ejecting ink droplets of "medium size" to all the ink ejection areas. Fig. 11 is a diagram showing an example of ejecting ink droplets of "small size" to all the ink ejection areas. Fig. 12 is a diagram showing an example in which after the ink ejection area is switched to an area in which ink ejection areas and non-ink ejection areas are alternately arranged, ink droplets of "medium size" are ejected to the switched ink ejection area. In fig. 10 to 12, the rectangular areas surrounded by straight lines correspond to one droplet.

When the tablet 9 is a tablet having a glossy surface such as a sugar-coated tablet, the ejected ink droplets easily move on the surface of the tablet 9. Therefore, a phenomenon in which ink droplets flow to connect with adjacent ink droplets, so-called mottle, easily occurs. The larger the conveying speed of the tablet 9, the more likely the occurrence of the unevenness. In fig. 10, an ink flow portion 92 in which the adjacent ink droplets 91 are connected to each other and flow is shown.

As shown in fig. 11, in order to reduce the occurrence of mottle, a method of reducing the size of the ink droplets 91 ejected to the respective ink ejection areas may be used. As shown in fig. 12, the present invention uses a method in which the continuous ink ejection area is switched to an area in which ink ejection areas and non-ejection areas are alternately arranged so that the ink ejection areas are discontinuous. Hereinafter, as shown in fig. 10 and 11, a Pattern in which the ink discharge area is continuous is referred to as a Solid Printing Pattern (Filled in Pattern). As shown in fig. 12, a Pattern in which the ink ejection area and the non-ejection area are alternately arranged is referred to as a checkerboard Pattern (checker).

Fig. 13 is a graph showing a relationship between a conveyance speed for each droplet size and pattern and a state of occurrence of mottle in an experiment performed using the tablet printing apparatus 1 according to the present embodiment. In fig. 13, "middle size/full plate" shows a case where a full plate pattern is printed by ink droplets of "middle size" as shown in fig. 10. As shown in fig. 11, "small size/full plate" shows a case where a full plate pattern is printed by the "small size" ink droplets. As shown in fig. 12, the "medium size/checkerboard" shows a checkerboard pattern printed by the "medium size" ink droplets. In fig. 13, "o" indicates a state where no unevenness is generated, "" Δ "indicates a state where the amount of unevenness generated is equal to or less than a predetermined amount," "x" indicates a state where the amount of unevenness generated is equal to or more than a predetermined amount, and "-" indicates that no experiment is performed.

As shown in fig. 13, the conveyance speed when the unevenness occurs is larger in the case of the "small size/full plate" than in the case of the "medium size/full plate". That is, "small size/full plate" is more difficult to mottle than "medium size/full plate". In addition, the conveyance speed when the unevenness occurs is larger in the case of the "medium size/checkerboard" than in the case of the "small size/full plate". That is, "medium size/checkerboard" is more difficult to create than "small size/full board". From this, it is understood that the pattern in which the ink ejection regions and the non-ejection regions are alternately arranged can very effectively suppress the occurrence of the mottle.

Thus, by reducing the number of ink ejection areas, the occurrence of mottle is suppressed. Therefore, in step S104, the data processing device 80 of the present embodiment converts the plurality of raster data D3 into thinned-out data D4 having fewer ink ejection pixels than the respective raster data D3. Then, by using the thinned data D4 as print data, it is possible to suppress the occurrence of mottle when the tablet printing apparatus 1 performs a printing process.

Further, by using the pattern in which the ink ejection regions and the non-ejection regions are alternately arranged as described above, occurrence of mottle is further suppressed. Therefore, in step S104, the data processing device 80 of the present embodiment converts the plurality of raster data D3 into a plurality of thinned-out data D4 in which ink ejection regions and non-ejection regions are alternately arranged. By using such sparse data D4 as print data, it is possible to further suppress the occurrence of mottle when the tablet printing apparatus 1 performs a printing process. By using the thinned-out data D4 as print data, the ink ejected onto the tablet 9 can be dried quickly. By using the thinned-out data D4 as print data, the amount of ink used can be reduced.

Here, several examples of patterns actually used as the sparse data D4 are described. Fig. 14 shows an example of a 50% sparse pattern. Fig. 15 shows an example of the sparse data D4 using the 50% sparse pattern shown in fig. 14. The pattern of the example of fig. 14 and 15 is a so-called checkerboard pattern in which one ink ejection area and one non-ejection area are alternately arranged in the vertical and horizontal directions. In the case of using such a pattern, the number of ink ejection pixels in the thinned data D4 is about 50% of the number of ink ejection pixels in the raster data D3.

Fig. 16 shows an example of a 62.5% sparse pattern. Fig. 17 shows an example of the sparse data D4 using the 62.5% sparse pattern shown in fig. 16. The patterns of the examples of fig. 16 and 17 are patterns in which 5 ink ejection regions and one non-ejection region arranged in a cross shape are alternately arranged in the vertical and horizontal directions. In the case of using such a pattern, the number of ink ejection pixels in the thinned data D4 is about 62.5% of the number of ink ejection pixels in the raster data D3. Using the 62.5% sparse pattern of the example of fig. 16 allows printing with a greater density than the 50% sparse pattern of the example of fig. 14.

Fig. 18 shows an example of a 37.5% sparse pattern. Fig. 19 shows an example of the sparse data D4 using the 37.5% sparse pattern shown in fig. 18. The patterns of the examples of fig. 18 and 19 are patterns in which one ink ejection region and five non-ejection regions arranged in a cross shape are alternately arranged in the vertical direction and the horizontal direction. When such a pattern is used, the number of ink ejection pixels in the thinned data D4 is about 37.5% of the number of ink ejection pixels in the raster data D3. Using the 35% sparse pattern of the example of fig. 18 can suppress mottle more than the 50% sparse pattern of the example of fig. 14.

Fig. 20 is an example of a 50% sparse pattern different from fig. 14. In the 50% thinning pattern of fig. 14, one ink ejection area and one non-ejection area are alternately arranged. On the other hand, the 50% thinning pattern in fig. 19 is a checkerboard-shaped pattern in which four ink ejection regions arranged in a square shape and four non-ejection regions arranged in a square shape are alternately arranged. The sparse data D4 may be constituted by such a pattern.

The sparse data D4 may be configured of a pattern other than the patterns illustrated in fig. 14 to 19. For example, in the pattern used for the thinned data D4, there may be a shape of a plurality of ink ejection groups each including adjacent ink ejection regions, or there may be a shape of a plurality of non-ejection groups each including adjacent non-ejection regions.

4. Flow of printing process in tablet printing apparatus

Next, the flow of the printing process according to the rotation angle in the tablet printing apparatus 1 will be described with reference to fig. 21. Fig. 21 is a flowchart showing a flow of the printing process of the tablet printing apparatus 1.

As shown in fig. 21, in the printing process of the tablet printing apparatus 1, first, a plurality of sparse data D4 are input from the data processing device 80 to the control unit 70. Thus, the print data holding unit 71 stores the plurality of input thinned data D4 as the print data D5 (step S201).

Fig. 22 is a diagram showing an example of the plurality of print data D5 stored in the print data holding unit 71. As shown in fig. 22, the print data holding unit 71 stores table data in which the rotation angle is associated with each print data D5.

Next, the control section 70 starts the conveyance of the tablets 9 in the tablet printing apparatus 1 (step S202). After the start of the conveyance, the first split line detection camera 32, the second split line detection camera 42, and the third split line detection camera 52 start acquiring images of the conveyed tablets 9, and output the acquired image data D6 to the control section 70. When the image data D6 is input to the control unit 70, the rotation angle detecting unit 72 detects the presence, front, back, and rotation angle of the tablet 9 held in each suction hole of the first conveying belt 41 and the second conveying belt 51 (step S203). Then, the rotation angle detecting unit 72 transmits the detection result D7 to the print data selecting unit 73.

Next, the print data selecting section 73 selects the print data D5 for printing the tablets 9 held by the first transport conveyor 41 and the second transport conveyor 51 from the print data holding section 71 based on the detection result D7, and transmits the print data to the ejection control section 74 (step S204).

Then, the discharge control unit 74 causes the first print head unit 43 and the second print head unit 53 to perform the printing process based on the print data D5 received from the print data selection unit 73 (step S205). Thereby, an image corresponding to the front and back surfaces and the rotation angle is recorded on each of the plurality of tablets 9 being conveyed.

The tablet printing apparatus 1 is provided with print data D5 for each rotation angle before the printing process. Thus, the print data D5 can be prepared without delay after the detection result D7 of the front surface, the back surface, and the rotation angle of the tablet 9 is acquired. Therefore, the processing speed of the printing process of the tablet printing apparatus 1 can be increased.

In the tablet printing apparatus 1, the simple raster data D3 is not used as the print data D5, but the thinned-out data D4 obtained by thinning out the raster data D3 is used as the print data D5. This can suppress the occurrence of the mottle and increase the processing speed of the printing process of the tablet printing apparatus 1.

5. Modification example

The main embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

The tablet printing apparatus 1 is an apparatus that prints on both sides of the tablet 9 by the first printing unit 40 and the second printing unit 50. However, the tablet printing apparatus of the present invention may be an apparatus that prints only one side of the tablet 9.

The data processing device 80 is connected to the control unit 70 of the tablet printing apparatus 1 so as to be able to communicate with each other, but the present invention is not limited thereto. For example, the print data D5 generated by the data processing device 80 may be input to the control unit 70 via a storage medium such as a CD-ROM.

The tablet printing apparatus 1 is provided separately from the data processing apparatus 80, but the present invention is not limited thereto. The tablet printing apparatus of the present invention may have the functions of the respective units of the data processing apparatus 80 in the control unit 70.

Further, the specific structure of the tablet printing apparatus 1 may be different from the drawings of the present application. In addition, the respective elements appearing in the above-described embodiments or modified examples may be appropriately combined within a range in which no contradiction occurs.

Description of the reference numerals

1 tablet printing device

9 tablets

32 first secant detection camera

40 first printing section

42 second secant detection camera

43 first print head Unit

50 second printing part

52 third secant detection camera

53 second print head Unit

70 control part

71 print data holding unit

72 rotation angle detecting part

73 print data selecting section

74 discharge control part

80 data processing device

81 vector rotation processing unit

82 image conversion processing section

83 thinning-out processing unit

431 print head

531 print head

D1 input data

D2 vector rotation data

D3 raster data

D4 sparse data

D5 print data

Claims

1. A data processing apparatus for creating print data for performing a print process on a surface of a tablet by an inkjet print head, the data processing apparatus comprising:

a vector rotation processing unit that performs vector rotation on input vector data and generates a plurality of vector rotation data corresponding to a plurality of rotation angles,

an image conversion processing section that converts each of the vector rotation data generated by the vector rotation processing section into raster data, an

A thinning-out processing unit that converts each of the plurality of raster data into thinned-out data having fewer ink ejection pixels than the raster data,

the raster data is data in which the ink ejection amount is set for each of the regions arranged in a lattice,

an ink ejection area from which ink is ejected in the thinned data is smaller than the ink ejection area in the raster data.

2. The data processing apparatus according to claim 1,

the thinning-out processing unit converts a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and the non-ink ejection regions are alternately arranged, and generates the thinning-out data.

3. The data processing apparatus according to claim 2,

the thinning-out processing unit converts a portion of the raster data where the ink discharge regions are continuous into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged, and generates the thinning-out data.

4. A tablet printing apparatus for printing on the surface of a tablet,

the tablet printing apparatus includes:

a data processing device for creating print data,

an ink jet printing head having a plurality of nozzles for ejecting ink droplets and performing a printing process by ejecting the ink droplets onto the surface of the tablet,

a camera disposed on an upstream side of the print head, detecting a rotation angle of the tablet, an

A control unit that controls ejection of the ink droplets from the print head;

the data processing apparatus has:

a vector rotation processing unit that performs vector rotation on the input vector data and generates a plurality of vector rotation data corresponding to a plurality of rotation angles, an

An image conversion processing unit that converts each of the vector rotation data into raster data;

the data processing apparatus outputs a plurality of print data based on a plurality of the raster data;

the control unit includes:

a print data holding section for holding a plurality of print data corresponding to the rotation angle, an

A print processing unit configured to select the print data from the print data holding unit based on the rotation angle detected by the camera and to cause the print head to perform print processing based on the selected print data;

the print data holding unit holds the plurality of print data input from the data processing device before the rotation angle is detected by the camera.

5. The tablet printing apparatus according to claim 4,

the data processing apparatus further includes a thinning-out processing unit that converts each of the plurality of raster data into thinned-out data having fewer ink ejection pixels than the raster data,

an ink ejection area from which ink is ejected in the thinned data is smaller than the ink ejection area in the raster data,

the data processing device outputs a plurality of the sparse data as the print data,

6. The tablet printing apparatus according to claim 5,

7. The tablet printing apparatus according to claim 6,

8. A data processing method for creating print data for performing a printing process on a surface of a tablet by an inkjet printing head, wherein the data processing method comprises:

a) a step of performing vector rotation on the input vector data and generating a plurality of vector rotation data corresponding to a plurality of rotation angles,

b) a step of converting each of the plurality of vector rotation data generated in the step a) into raster data, an

c) Converting each of the plurality of raster data into sparse data having fewer ink ejection pixels than the raster data,

9. The data processing method of claim 8,

in the step c), the thinned-out data is generated by converting a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and the non-ink ejection regions are alternately arranged.

10. The data processing method of claim 9,

in the step c), the thinned-out data is generated by converting a portion of the raster data in which the ink discharge regions are continuous into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged.

11. A tablet printing method for performing a printing process on a surface of a tablet by an inkjet printing head, wherein the tablet printing method comprises:

B) a step of converting each of the plurality of vector rotation data into raster data,

C) a step of holding a plurality of print data corresponding to the rotation angle based on the raster data obtained in the step B),

D) a step of detecting the rotation angle of the tablet after the step C),

E) a step of selecting the print data to be used for the printing process from the plurality of print data based on the rotation angle after the step D), and

F) a step of printing an image on the surface of the tablet based on the print data selected in the step E).

12. The tablet printing method according to claim 11,

the tablet printing method further includes a step G) of converting each of the plurality of raster data into thinned-out data having a smaller number of pixels to which ink is ejected than the raster data after the step B) and before the step C),

in the step C), a plurality of the sparse data are held as a plurality of the print data,

13. The tablet printing method according to claim 12,

in the step G), the thinned-out data is generated by converting a portion of the raster data where the ink ejection regions are continuous into a pattern in which the ink ejection regions and the non-ink ejection regions are alternately arranged.

14. The tablet printing method according to claim 13, wherein,

in the step G), the thinned-out data is generated by converting a portion of the raster data in which the ink discharge regions are continuous into a pattern in which the ink discharge regions having a quadrangular shape and the non-ink discharge regions having a quadrangular shape are alternately arranged.