CN111801084B

CN111801084B - Printing apparatus and printing method

Info

Publication number: CN111801084B
Application number: CN201980017099.7A
Authority: CN
Inventors: 中野信行
Original assignee: Screen Holdings Co Ltd
Current assignee: Screen Holdings Co Ltd
Priority date: 2018-03-05
Filing date: 2019-01-21
Publication date: 2022-08-02
Anticipated expiration: 2039-01-21
Also published as: JP6921769B2; JP2019150359A; KR102505696B1; WO2019171791A1; CN111801084A; KR20200111786A

Abstract

A printing apparatus (1) includes a conveyance mechanism (10), an imaging mechanism (20), and a head (30). The conveying mechanism (10) reciprocally conveys tablets (9) as granules between a first position (P1) and a second position (P2). The imaging mechanism (20) images the tablet (9) at an imaging position (Pa) between a first position (P1) and a second position (P2). The head (30) ejects ink droplets onto the surface of the tablet (9) at a printing position (Pb) between the imaging position (Pa) and the second position (P2). By reciprocating the tablet (9), the tablet (9) before printing and the tablet (9) after printing can be photographed by one photographing mechanism (20). This facilitates the miniaturization of the printing apparatus (1).

Description

Printing apparatus and printing method

Technical Field

The present invention relates to a printing apparatus and a printing method for printing an image on a surface of a particulate matter by an inkjet method.

Background

Characters and codes for identifying products are printed on the surface of tablets as pharmaceutical products. Further, marks and illustrations may be printed on the candy tablet such as a margarine. Conventionally, there is known a technique of printing an image on the surface of such a granular material such as a tablet or a candy by an ink jet method. For example, patent document 1 describes a tablet printing apparatus that performs a printing process on a tablet that is randomly supplied by an inkjet printer.

The device of patent document 1 includes: a line sensor camera (detection imaging means) for detecting the image of the tablet before printing; and an inspection line sensor camera (inspection imaging means) for imaging the printed tablet. The device of patent document 1 prints on each tablet based on the position, posture, front and back surfaces, and the like of the tablet detected by the line sensor camera for detection. Further, the inspection line sensor camera is used to inspect the printing state of each tablet.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-121432

Disclosure of Invention

Problems to be solved by the invention

However, in the configuration described in patent document 1, at least two image pickup units, i.e., a line sensor camera for detection and a line sensor camera for inspection, are required. Therefore, it is difficult to miniaturize the printing apparatus. Further, the manufacturing cost of the printing apparatus increases due to the plurality of imaging units.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique capable of reducing the number of imaging mechanisms in a printing apparatus for printing an image on the surface of a particulate matter by an inkjet method.

Means for solving the problems

In order to solve the above problems, a first aspect of the present invention is a printing apparatus for printing an image on a surface of a granular object by an ink jet method, the printing apparatus including: a conveying mechanism that performs outbound conveyance for conveying the pellets from a first position to a second position and loop conveyance for conveying the pellets from the second position to the first position; an imaging mechanism that images the granular object at an imaging position between the first position and the second position; a head that ejects ink droplets onto the surface of the particulate matter at a printing position between the imaging position and the second position; and a control unit that controls the transport mechanism, the imaging mechanism, and the head, wherein the control unit executes: a) shooting the granular objects in the outgoing transport by the shooting mechanism; b) ejecting ink droplets from the head onto the surface of the particulate matter during the outward transport or the return transport after the step a); and c) after the step b), shooting the granular objects in the loop by the shooting mechanism.

A second aspect of the present invention is the printing apparatus according to the first aspect, wherein in the step b), the control unit ejects ink droplets from the heads onto the surface of the particulate matter being conveyed in the outward path.

A third aspect of the present invention is the printing apparatus according to the first or second aspect, wherein the conveyance mechanism includes: a holding plate having an adsorption hole for adsorbing the particulate matter; and a plate moving mechanism that moves the holding plate between the first position and the second position.

A fourth aspect of the present invention is the printing apparatus according to any one of the first to third aspects, wherein the control unit performs the pre-printing inspection of the particulate matter based on the image obtained in the step a), and the control unit performs the post-printing inspection of the particulate matter based on the image obtained in the step c).

A fifth aspect of the present invention is the printing apparatus of any one of the first to fourth aspects, further comprising a cover that covers at least a part of the transport path between the first position and the second position, the imaging mechanism, and the head, wherein the cover has an opening for carrying in and out the particulate matter at the first position.

A sixth aspect of the present invention is the printing apparatus of any one of the first to fifth aspects, further comprising a turnover mechanism for turning over front and back sides of the particulate matter, wherein the control unit, after executing the steps a) to c), turns over the front and back sides of the particulate matter by the turnover mechanism and executes the steps a) to c) again.

A seventh aspect of the present invention is the printing apparatus of any one of the first to sixth aspects, wherein the granular material is a tablet.

An eighth aspect of the present invention is a printing method for printing an image on a surface of a particulate matter by an inkjet method, the printing method including: a) shooting the granular objects in the outward path conveying from the first position to the second position by a shooting mechanism; b) ejecting ink droplets from a head onto the surface of the particulate matter being conveyed in the outward path or in the return path from the second position to the first position after the step a); and c) after the step b), shooting the granular objects in the loop by the shooting mechanism.

A ninth aspect of the present invention is the printing method according to the eighth aspect, wherein in the step b), ink droplets are ejected from the head onto the surface of the particulate matter being conveyed in the outward path.

A tenth aspect of the present invention is the printing method according to the eighth or ninth aspect, wherein the granular material is a tablet.

Effects of the invention

According to the first to tenth aspects of the present invention, by reciprocating the granular objects, it is possible to perform imaging of the granular objects before printing and imaging of the granular objects after printing by one imaging means. This facilitates downsizing of the printing apparatus.

In particular, according to the second and ninth aspects of the present invention, the position of the particulate matter is less likely to be displaced from the imaging of the particulate matter in the step a) to the ejection of the ink droplets in the step b). Therefore, based on the imaging result of the particulate matter in the step a), an image can be printed on the surface of the particulate matter with high accuracy.

Drawings

Fig. 1 is a plan view of a printing apparatus.

Fig. 2 is a side view of the printing apparatus.

Fig. 3 is a block diagram showing connections between the control unit and each unit in the printing apparatus.

Fig. 4 is a flowchart showing a flow of processing in the printing apparatus.

Fig. 5 is a flowchart showing a processing flow of the modification.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, a direction in which a plurality of granular materials are conveyed is referred to as a "conveyance direction", a direction perpendicular and horizontal to the conveyance direction is referred to as a "width direction", and a direction perpendicular to the conveyance direction and the width direction is referred to as a "height direction".

<1 > Structure of printing apparatus

Fig. 1 is a plan view of a printing apparatus 1 according to an embodiment of the present invention. Fig. 2 is a side view of the printing apparatus 1. The printing apparatus 1 is an apparatus that prints an image on the surface of each tablet 9 by an inkjet method while conveying a plurality of tablets 9 as granules. The tablet 9 may be an uncoated tablet (bare tablet) or a coated tablet such as a sugar-coated tablet or a film-coated tablet (FC tablet). In addition, the tablet 9 may be a capsule including a hard capsule and a soft capsule. The "granules" in the present invention are not limited to tablets as a pharmaceutical, and may be tablets as a health food, and tablets such as marjoram candy.

As shown in fig. 1 and 2, the printing apparatus 1 of the present embodiment includes a conveyance mechanism 10, an imaging mechanism 20, a head 30, a cover 40, and a control unit 50.

The conveying mechanism 10 is a mechanism that holds and conveys a plurality of tablets 9. The conveying mechanism 10 of the present embodiment includes a holding plate 11, a suction mechanism 12, and a plate moving mechanism 13. The holding plate 11 is a flat plate-like holding portion that holds the plurality of tablets 9. The holding plate 11 is configured such that its upper surface is in a horizontal posture. A plurality of suction holes 110 are provided in the upper surface of the holding plate 11. The plurality of suction holes 110 are arranged at equal intervals in the conveyance direction and the width direction, for example. One tablet 9 is disposed on each of the adsorption holes 110.

The suction mechanism 12 is a mechanism for generating a negative pressure in the plurality of suction holes 110. As shown in fig. 2, the suction mechanism 12 includes a suction pipe 121 and an airflow generating device 122. One end of the suction pipe 121 is connected to the plurality of suction holes 110. The other end of the intake pipe 121 is connected to an airflow generating device 122. The airflow generating device 122 uses a fan, for example. When the air flow generator 122 is driven, an air flow flowing from the plurality of adsorption holes 110 to the air flow generator 122 is generated in the air intake pipe 121. This generates a negative pressure lower than the atmospheric pressure in the plurality of adsorption holes 110. The tablet 9 is sucked and held by the suction hole 110 due to the negative pressure.

The plate moving mechanism 13 is a mechanism for moving the holding plate 11. The plate moving mechanism 13 uses, for example, a linear motor. However, a mechanism that converts the rotational motion of the motor into linear motion by a ball screw may be used instead of the linear motor.

When the plate moving mechanism 13 is operated, the holding plate 11 horizontally reciprocates between a first position P1 indicated by a solid line in fig. 1 to 2 and a second position P2 indicated by a two-dot chain line in fig. 1 to 2. The first position P1 is a position where the holding plate 11 carries the tablet 9 in and out. The second position P2 is a retracing position of the reciprocating movement. By the movement of the holding plate 11, the conveyance (forward conveyance) of the plurality of tablets 9 from the first position P1 to the second position P2 and the conveyance (return conveyance) of the plurality of tablets 9 from the second position P2 to the first position P1 are realized.

As described above, the holding plate 11 holds the tablet 9 by suction under negative pressure, instead of simply placing the tablet 9. This can suppress the position and posture of the tablet 9 from changing or the tablet 9 from falling off when the tablet 9 is conveyed. In particular, when switching from the outward conveying to the return conveying, a large inertial force in the conveying direction acts on the tablets 9. However, in the present embodiment, since the tablet 9 is held by adsorption, the position and posture of the tablet 9 can be maintained.

The imaging mechanism 20 is a mechanism that images the upper surface of the tablet 9 at an imaging position Pa between the first position P1 and the second position P2. As shown in fig. 1 and 2, the imaging mechanism 20 of the present embodiment includes a mirror 21 and a camera 22. The mirror 21 is disposed above the imaging position Pa in an inclined posture with respect to the height direction and the width direction. The camera 22 is a digital camera having an imaging element such as a CCD or a CMOS. The camera 22 takes an image of the tablet 9 reflected by the mirror 21. Thereby, digital data of multi-gradation including the image of tablet 9 is obtained. As in the present embodiment, if the mirror 21 is used, the camera 22 can be disposed on the side of the mirror 21 rather than above the imaging position Pa. This can suppress the height of the printing apparatus 1.

The head 30 is a mechanism for ejecting ink droplets onto the upper surface of the tablet 9 at a printing position Pb between the imaging position Pa and the second position P2. A plurality of nozzles are provided on the lower surface of the head 30. The head 30 ejects ink droplets from the respective nozzles based on print data input from the control section 50. Thereby, an image is printed on the upper surface of the tablet 9. The printing apparatus 1 of the present embodiment prints a single color image on the upper surface of the tablet 9 by one head 30. However, the printing apparatus 1 may be provided with a plurality of heads 30, and a multicolor image may be recorded on the upper surface of the tablet 9 by ejecting ink of different colors from the heads 30. Further, edible ink manufactured from raw materials approved by japanese pharmacopoeia, food hygiene law, and the like is used as ink ejected from the head 30.

The printing apparatus 1 may further include a mechanism for cleaning a cover covering the lower surface of the head 30 and the lower surface of the head 30 when printing is stopped.

The cover 40 constitutes a part of the housing of the printing apparatus 1. The shooting mechanism 20, the head 30, and at least a part of the conveyance path between the first position P1 and the second position P2 are covered by the cover 40. In addition, the cover 40 has an opening 41 in the vicinity of the first position P1. When the tablet 9 is fed, the holding plate 11 is placed at the first position P1, and the tablet 9 is placed on the upper surface of the holding plate 11 exposed to the outside through the opening 41. When the tablet 9 is fed out, the holding plate 11 is placed at the first position P1, and the tablet 9 is taken out from the upper surface of the holding plate 11 exposed to the outside through the opening 41.

The control unit 50 is a unit for controlling the operation of each unit of the printing apparatus 1. Fig. 3 is a block diagram showing the connection between the control unit 50 and each unit in the printing apparatus 1. As schematically shown in fig. 1, the control unit 50 is constituted by a computer having a processor 51 such as a CPU, a memory 52 such as a RAM, and a storage unit 53 such as a hard disk drive. The storage unit 53 stores therein a computer program CP and data D for executing a printing process and an inspection process, which will be described later.

As shown in fig. 3, the control unit 50 is communicably connected to the suction mechanism 12, the plate moving mechanism 13, the camera 22, and the head 30 by wire or wirelessly. The control unit 50 temporarily reads out the computer program CP and the data D stored in the storage unit 53 to the memory 52, and the processor 51 performs operation control of the above-described units by performing arithmetic processing based on the computer program CP. Thereby, the printing process and the inspection process for the plurality of tablets 9 are performed.

In addition, the printing apparatus 1 includes the display unit 60 in addition to the above configuration. The display unit 60 is communicably connected to the control unit 50 by wire or wirelessly. The display unit 60 uses, for example, a liquid crystal display. The display unit 60 displays various information related to a printing process and an inspection process, which will be described later, on a screen based on a signal input from the control unit 50.

<2 > regarding printing process and inspection process

The printing apparatus 1 performs the pre-printing inspection, the printing, and the post-printing inspection on the tablets 9 in this order while reciprocating the plurality of tablets 9 between the first position P1 and the second position P2. The flow of these processes will be described below with reference to the flowchart of fig. 4.

In the initial state, the holding plate 11 is arranged at the first position P1. A user of the printing apparatus 1 first places the tablet 9 on the plurality of suction holes 110 of the holding plate 11. The tablet 9 is sucked and held in each suction hole 110 by the negative pressure generated by the suction mechanism 12 (step S1).

When the plurality of tablets 9 are held by the holding plate 11, the control section 50 starts the operation of the plate moving mechanism 13. Thereby, the holding plate 11 and the outward conveying of the plurality of tablets 9 held by the holding plate 11 from the first position P1 to the second position P2 are started (step S2).

When the plurality of tablets 9 reach the imaging position Pa, the control unit 50 operates the camera 22 of the imaging mechanism 20. Thereby, the camera 22 photographs the upper surfaces of the plurality of tablets 9 being conveyed on the way (step S3). The acquired image data is transmitted from the camera 22 to the control unit 50. Further, the control unit 50 checks the state of each tablet 9 before printing (pre-printing check) based on the image data received from the camera 22 (step S4). Specifically, the presence or absence of the tablet 9 in each suction hole 110, the front-back posture of each tablet 9, the rotational posture of each tablet 9 about the vertical axis, the positional deviation of each tablet 9 with respect to the suction hole 110, the presence or absence of shape defects in each tablet 9, and the like are determined. The result of the check at step S4 is displayed on the display unit 60.

Next, when the plurality of tablets 9 reach the printing position Pb, the control section 50 operates the head 30. Thereby, ink droplets are ejected from the plurality of nozzles of the ejection head 30 toward the tablet 9. As a result, an image is printed on the upper surface of each tablet 9 being conveyed in the outward path (step S5). At this time, the control unit 50 adjusts the image to be printed on each tablet 9 based on the result of the check at step S3. For example, the control section 50 selects an appropriate image from the front side image and the back side image in accordance with the front and back side postures of the respective tablets 9, and rotates the selected image in accordance with the rotation posture of the respective tablets 9. Then, the control unit 50 inputs a print signal to the head 30 based on the adjusted image. As a result, an appropriate image is printed on the upper surface of each tablet 9 in an appropriate posture.

After that, when the tablet 9 reaches the second position P2, the control unit 50 stops the operation of the plate moving mechanism 13. Thereby, the holding plate 11 and the outward conveying of the plurality of tablets 9 held by the holding plate 11 are completed (step S6). Thereafter, the controller 50 operates the board moving mechanism 13 in the direction opposite to the steps S2 to S6. Thereby, the holding plate 11 and the loop conveyance of the plurality of tablets 9 held on the holding plate 11 from the second position P2 to the first position P1 are started (step S7).

In the circuit conveyance, the ejection of ink droplets from the head 30 is not performed, and the plurality of tablets 9 pass through the printing position Pb. When the plurality of tablets 9 reach the imaging position Pa, the control unit 50 operates the camera 22 of the imaging mechanism 20. Thereby, the camera 22 photographs the upper surfaces of the plurality of tablets 9 in the circuit conveyance (step S8). The acquired image data is transmitted from the camera 22 to the control unit 50.

Further, the control section 50 performs an inspection (post-printing inspection) of the printing state of each tablet 9 based on the image data received from the camera 22 (step S9). Specifically, the control unit 50 compares the image data received from the camera 22 with data of a normal image prepared in advance, for example, to determine whether or not the image printed on the upper surface of each tablet 9 is normal. The result of the check at step S9 is displayed on the display unit 60.

After that, when the tablet 9 reaches the first position P1, the control unit 50 stops the operation of the plate moving mechanism 13. This completes the circuit conveyance of the holding plate 11 and the plurality of tablets 9 held by the holding plate 11 (step S10). After that, the control unit 50 stops the operation of the suction mechanism 12. Thereby, the adsorption of the tablet 9 on each adsorption hole 110 is released. The user of the printing apparatus 1 takes out the plurality of printed tablets 9 from the holding plate 11 (step S11).

As described above, in the printing apparatus 1, the imaging of the tablet 9 before printing (step S3), the printing (step S5), and the imaging of the tablet 9 after printing (step S8) are sequentially performed while the tablet 9 is being transported back and forth. The photographing of the tablet 9 before printing (step S3) and the photographing of the tablet 9 after printing (step S8) are performed by the same photographing mechanism 20 at the same photographing position Pa. Therefore, the number of imaging means can be reduced compared to the case where the imaging of the tablet 9 before printing (step S3) and the imaging of the tablet 9 after printing (step S8) are performed by different imaging means. Therefore, if the configuration of the present embodiment is adopted, the printing apparatus 1 can be easily downsized.

In particular, in the present embodiment, the printing of the tablets 9 is performed during the outward conveyance. In this way, immediately after the photographing of tablet 9 before printing (step S3) and the inspection before printing (step S4), the printing can be performed (step S5). Further, the imaging of the tablet 9 before printing (step S3), the inspection before printing (step S4), and the printing (step S5) can be performed without switching the conveying direction of the tablet 9. Therefore, during the period from the imaging of the tablet 9 before printing (step S3) and the inspection before printing (step S4) to the printing, the positional displacement of the tablet 9 is less likely to occur. Therefore, based on the inspection result of step S4, an image can be printed on the upper surface of each tablet 9 with high accuracy.

<3. modification >

While one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

In the above embodiment, the printing of the tablet 9 is performed during the outgoing transport. However, the printing of the tablets 9 can also be carried out in a loop transport. Fig. 5 is a flowchart when printing is performed during loop conveyance. In the example of fig. 5, in the outgoing transport, only the photographing of the tablet 9 (step S3) and the pre-printing inspection (step S4) are performed. Then, when the conveying direction is switched at the second position P2 (steps S6 to S7), ink droplets are ejected from the head 30 onto the upper surface of the tablet 9 being conveyed in the circuit, and printing is performed (step S5). After that, photographing of the tablet 9 in the loop conveyance (step S8) and post-printing inspection (step S9) are performed.

In the above embodiment, a plurality of tablets 9 are directly placed on the upper surface of the holding plate 11. However, a plurality of tablets 9 may be placed on the upper surface of the holding plate 11 via a separate tray. The tray may have a shape that can be attached to and detached from the holding plate 11, and may have through holes at positions corresponding to the suction holes 110. In addition, a recess may be provided in a position corresponding to the suction hole 110 on the upper surface of the holding plate 11 or the upper surface of the tray. Then, the tablet 9 may be embedded in the recess. Thus, the positional deviation of the tablet 9 accompanying the conveyance can be further suppressed.

In addition, in the above embodiment, the tablet 9 is horizontally conveyed between the first position P1 and the second position P2. However, the direction of conveying the tablet 9 between the first position P1 and the second position P2 may be an oblique direction or a vertical direction. In addition, in the above embodiment, the tablets 9 are linearly conveyed between the first position P1 and the second position P2. However, the conveying path of the tablet 9 between the first position P1 and the second position P2 may be curved or broken.

In addition, in the above embodiment, the conveying mechanism 10 conveys the tablet 9 through the holding plate 11. However, the conveying mechanism of the present invention may convey the tablets 9 by other methods. For example, the tablet 9 may be conveyed by rotating the conveyor belt while holding the tablet 9 by suction on the surface of the conveyor belt of the belt conveyor. Further, the tablet 9 may be conveyed by rotating a drum (drum) while holding the tablet 9 by suction on the surface of the drum having a cylindrical shape.

In addition to the configuration of the printing apparatus 1 according to the above embodiment, a turning mechanism may be provided to turn the front and back sides of the tablet 9 on the holding plate 11. The turning mechanism may be, for example, a mechanism that turns over the tablets 9 from one holding plate or tray to another holding plate or tray. When printing is performed on the tablet 9, for example, steps S1 to S10 in fig. 4 are executed, then the front and back sides of the tablet 9 are reversed, and steps S2 to S11 in fig. 4 are executed. If such a turnover mechanism is added, images can be automatically printed on both the front and back surfaces of the tablet 9. Therefore, the inspection before printing, the inspection after printing, and the inspection before printing on one surface of tablet 9 can be performed by the same mechanism as the inspection before printing, the inspection after printing, and the inspection after printing on the other surface of tablet 9. This enables the printing apparatus 1 to be significantly reduced in size.

In addition to the configuration of the printing apparatus 1 according to the above embodiment, a drying mechanism for drying the ink adhering to the surface of the tablet 9 may be provided. The drying means may be configured to blow hot air to the upper surface of the tablet 9, for example, to vaporize the solvent in the ink adhering to the upper surface of the tablet 9. The drying mechanism may be disposed at the second position P2, for example.

The configuration of the details of the printing apparatus may be appropriately modified without departing from the spirit of the present invention. In addition, the respective elements appearing in the above embodiments and the modified examples may be appropriately combined within a range in which no contradiction occurs.

Description of the symbols

1 printing device

9 tablets

10 conveying mechanism

11 holding plate

12 suction mechanism

13 board moving mechanism

20 shooting mechanism

21 reflector

22 Camera

30 spray head

40 cover

41 opening

50 control part

60 display part

110 adsorption hole

121 air intake pipe

122 airflow generating device

P1 first position

P2 second position

Pa imaging position

Pb printing position.

Claims

1. A printing apparatus for printing an image on a surface of a particulate matter by an inkjet method, the printing apparatus comprising:

a conveying mechanism that performs outbound conveyance for conveying the pellets from a first position to a second position and loop conveyance for conveying the pellets from the second position to the first position;

an imaging mechanism that images the granular object at an imaging position between the first position and the second position;

a head that ejects ink droplets onto the surface of the granular object at a printing position between the imaging position and the second position; and

a control unit that controls the transport mechanism, the imaging mechanism, and the head,

the control unit executes the following steps:

a) shooting the granular objects in the outgoing transport by the shooting mechanism;

b) ejecting ink droplets from the head onto the surface of the particulate matter during the outward transport or the return transport after the step a); and

c) after the step b), the granular object being conveyed in the loop is photographed by the photographing means.

2. Printing device according to claim 1,

in the step b), the control unit ejects ink droplets from the ejection head onto the surface of the particulate matter being conveyed in the outward path.

3. Printing device according to claim 1 or 2,

the conveying mechanism is provided with:

a holding plate having an adsorption hole for adsorbing the particulate matter; and

a plate moving mechanism that moves the holding plate between the first position and the second position.

4. Printing device according to claim 1 or 2,

the control unit performs a pre-printing inspection of the particulate matter based on the image obtained in the step a),

the control unit performs post-printing inspection of the particulate matter based on the image obtained in the step c).

5. Printing device according to claim 1 or 2,

the printing apparatus further includes: a cover that covers at least a part of the transport path between the first position and the second position, the photographing mechanism, and the ejection head,

the hood has an opening for carrying in and out the pellets at the first location.

6. Printing device according to claim 1 or 2,

the printing apparatus further includes: a turnover mechanism for turning over the front and back sides of the granular material,

the control unit may perform the steps a) to c) again by reversing the front and back sides of the granular material by the reversing mechanism after performing the steps a) to c).

7. Printing device according to claim 1 or 2,

the granulate is a tablet.

8. A printing method for printing an image on the surface of a granular object by an ink jet method, the printing method comprising the steps of:

a) shooting the granular objects in the outward path conveying from the first position to the second position by a shooting mechanism;

b) ejecting ink droplets from a head onto the surface of the particulate matter being conveyed in the outward path or in the return path from the second position to the first position after the step a); and

9. The printing method according to claim 8,

in the step b), ink droplets are ejected from the head onto the surface of the particulate matter being transported in the outward path.

10. The printing method according to claim 8 or 9,

the granulate is a tablet.