JP6838927B2 - Tablet printing device and tablet printing method - Google Patents

Description

Embodiments of the present invention relate to a tablet printing apparatus and a tablet printing method.

A device using an inkjet head is known as a device for printing characters, marks, and the like on the surface of a tablet.

In this inkjet head, as in Patent Document 1, in order to use the ink supplied to the inkjet head without waste, the inkjet head is provided with supply and discharge, and the ink that has passed through the inkjet head can be returned from the discharge to the supply tank. It is done.

Japanese Unexamined Patent Publication No. 2003-275569

However, in tablet printing, cleaning is performed as maintenance of the printing apparatus for several hours or one day from the viewpoint of hygiene, or at the timing of switching varieties or switching lots. In particular, in cleaning the inkjet head and piping through which ink passes, it takes time not only in a complicated piping system as in Patent Document 1, but also confirmation of whether complicated parts such as valves in various places are surely cleaned. It is difficult.

Further, depending on the ink, agglutination of ink components is likely to occur. If there is such an agglomerated aggregate of ink components, the flow path may be narrowed in the inkjet head or the ejection nozzle of the inkjet head may be clogged, resulting in ejection failure.

The present invention is to provide a tablet printing apparatus and a tablet printing method capable of easily and surely performing maintenance and appropriately printing on a tablet.

The tablet printing apparatus according to the embodiment is
Conveyor and
An inkjet head that prints by ejecting ink from a nozzle on tablets transported by the transfer device.
An ink bottle containing ink supplied to the inkjet head via a supply tube connected to the inkjet head, and an ink bottle.
An discharge bottle provided separately from the ink bottle and accommodating ink discharged from the inkjet head via a discharge pipe connected to the inkjet head.
An on-off valve provided in the discharge pipe and
And at least the conveying device, the control unit controlling each part of the on-off valve provided in the ink jet head and the discharge pipe,
The control unit
A first state in which the end face of the supply pipe on the ink bottle side is arranged so as to be located in the ink contained in the ink bottle.
Emissions formed and the height of the nozzle forming surface of the nozzle of the ink-jet head is formed by a height of the liquid level of the ink in the height of the end face of the discharge bottle side of the ink discharge tube or discharge bottle water head difference of the side is, the the height of the liquid surface of the ink in the ink bottle, the height of the nozzle surface, the second that provided greater than the water head difference between the supply side, which is formed by the state,
Water head difference between the discharge side and the water head difference between the supply side, the so ambient air from the nozzle is less than the water head difference will be drawn, the height of the end face of the discharge bottle side of the ink of the discharge tube is Ru is set Third state,
With all the states of is maintained at the same time, discharge of the off valve in Rukoto be controlled to from the closed to the open, into the discharge bottle of the ink in the ink-jet head by using only the water head difference When, and carrying out the supply of the ink from the ink bottle into the ink jet head, simultaneously.

The tablet printing method according to the embodiment is
In a tablet printing method in which printing is performed on a conveyed tablet using an inkjet head that ejects ink from a nozzle.
To the inkjet headThrough the connected supply pipeThe ink from the ink bottle To the inkjet headWith the steps to supply
The step of printing with the inkjet head and
The step of timing the time based on the printing process and
When the timed time reaches a predetermined time, the printing process is stopped.The ink jet From ToheadThe ink, In a discharge bottle different from the ink bottleSteps to discharge and
The step of timing the time when the ink is discharged and
When the time for discharging the timed ink reaches a predetermined time, the step of stopping the discharge of the ink and restarting the printing process is provided.
In the step of ejecting the ink,
The end face of the supply pipe on the ink bottle side is housed in the ink bottle. The first state, which is located so that it is located in the ink,
Of the inkjet head,The head difference on the discharge side formed on the ink discharge side is provided to be larger than the head difference on the supply side formed on the ink supply side.Second state,
The head difference on the supply side and the head difference on the discharge side are provided so as to be smaller than the head difference in which outside air is sucked from the nozzle.Third state,
The on-off valve provided in the discharge pipe is opened from the closed state while all the states are maintained at the same time. By using only the head difference, the ink in the inkjet head is said to be in the ink. Discharge to the discharge bottle and the ink from the ink bottle to the inkjet head. It is characterized by supplying and performing at the same time...

According to the present invention, it is possible to provide a tablet printing apparatus and a tablet printing method capable of easily and surely performing maintenance and appropriately printing on a tablet.

It is a front view which shows the whole structure of the tablet printing apparatus which concerns on embodiment of this invention. It is a block diagram which shows the structure of the inkjet printing part of the 1st printing part which concerns on 1st Embodiment of this invention. It is a flowchart which shows the flow of tablet printing which concerns on embodiment of this invention. It is a figure which shows the state which the ink in the ink bottle shown in FIG. 2 is consumed. It is a flowchart which shows the flow of the ink discharge process which concerns on embodiment of this invention. It is a figure which shows the state of the liquid level of the ink in the discharge bottle shown in FIG. It is a block diagram which shows the structure of the inkjet printing part of the 1st printing part which concerns on other embodiment of this invention. It is a block diagram which shows the structure of the inkjet printing part of the 1st printing part which concerns on other embodiment of this invention.

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

(First Embodiment)
FIG. 1 is a front view showing the overall configuration of the tablet printing apparatus S according to the first embodiment. The tablet printing device S includes a transport device C for transporting tablets (not shown) to be printed, and a printing unit P for printing on the tablets transported by the transport device C.

As shown in FIG. 1, the transfer device C is composed of a first transfer device 1 and a second transfer device 2, and the first transfer device 1 and the second transfer device 2 thereof are arranged vertically. ing.

The printing unit P is composed of a first printing unit 3 and a second printing unit 4.

That is, the first printing unit 3 is provided on the upper portion of the first transport device 1, and the second printing unit 4 is provided on the upper portion of the second transport device 2, respectively, and the tablet printing device S is provided as a whole. It is configured.

In the first embodiment, the first transfer device 1 and the second transfer device 2, or the first printing unit 3 and the second printing unit 4 have the same basic configurations. To do.

The first transfer device 1 includes a first pulley 11, a second pulley 12, an endless transfer belt 13, and a suction chamber 14.

The first pulley 11 is the left pulley of the two pulleys shown in a circular shape on the first transfer device 1 in FIG. The second pulley 12 is the right pulley of the above-mentioned two pulleys in FIG.

The transport belt 13 has an endless shape that is hung on the first pulley 11 and the second pulley 12 and has no end portion. Therefore, the transport belt 13 rotates when the first pulley 11 and the second pulley 12 rotate.

The transport belt 13 is provided with a suction hole (not shown) for sucking air in order to hold the tablet to be printed during transport. The tablets are sucked and held on the surface of the transport belt 13 by suction through the suction holes. A suction chamber 14 is provided on the back surface of the transport belt 13 for this suction.

The suction chamber 14 applies a suction force to the suction holes of the transport belt 13. When the suction chamber 14 sucks air, the tablets are sucked and held by the transport belt 13 through the suction holes. By providing such a function, the suction chamber 14 is configured to be able to apply a suction force to the suction holes at an arbitrary position on the entire circumference of the transport belt 13.

The first transfer device 1 adopts the above-described configuration, and both the first pulley 11 and the second pulley 12 rotate clockwise. Therefore, in the first transfer device 1, the transfer belt 13 advances in the direction of the arrow indicated by the solid line in the upper horizontal region, that is, to the right from the first pulley 11 to the second pulley 12.

On the upper side of the first transfer device 1, the first printing unit 3 is positioned at a position facing the surface of the transfer belt 13 that advances from the first pulley 11 to the second pulley 12. .. Therefore, when printing on a tablet in the first printing unit 3, the tablet is placed on the transport belt 13 and transported below the first printing unit 3.

The first printing unit 3 is an inkjet printing unit 31 that prints on a tablet, a position detecting device 32 that detects a position of the tablet (for example, a position on a transport belt 13 on which the tablet is adsorbed and held), and a tablet. It has a print state confirmation device 33 for confirming the print state.

The inkjet printing unit 31 prints on the upper surface of the tablet. The inkjet printing unit 31 includes, for example, an inkjet head 311 which is an inkjet printing head. The ink used is an edible ink as described above.

The position detection device 32 is provided on the upstream side of the transfer belt 13 in the traveling direction with respect to the inkjet head 311 included in the inkjet printing unit 31, and the position and orientation (direction, inclination, etc.) of the tablet held on the surface of the transfer belt 13 ) Is a device that detects. The position detection device 32 includes a photographing device 321 for photographing a tablet and an illumination 322 for illuminating the tablet to be photographed. The photographing device 321 photographs the tablet, captures the photographed image, and transmits the photographed image to the control unit 5. That is, the control unit 5 plays a part of the configuration of the first printing unit 3 (position detection device 32) as an example. The control unit 5 detects the position and orientation of the tablet based on the captured image, and prints appropriately based on the detection result (if there is a misalignment, the misalignment is corrected and printed). It determines and controls whether to drive the printing unit 31 or not to print.

The print state confirmation device 33 is provided on the downstream side of the transport belt 13 in the traveling direction with respect to the inkjet head 311 and is a device for confirming the print state on the upper surface of the tablet by the inkjet head 311.

The print state confirmation device 33 includes a photographing device 331 for photographing the printed state of the tablet and an illumination 332 for illuminating the tablet to be photographed. The photographing device 331 photographs the tablet, captures the photographed image, and transmits the photographed image to the control unit 5. Therefore, the control unit 5 plays a part of the configuration of the first printing unit 3 (printing state confirmation device 33) as an example.

The control unit 5 detects the printing state based on the image captured by the photographing device 331, and determines whether the printing is good or bad. Tablets judged to be defective in printing are transferred to a defective product collection box as described later.

Further, a hopper 15 is provided on the left side of the first pulley 11 of the first transfer device 1. A large number of tablets are housed in the hopper 15, and the tablets can be supplied to the transport belt 13.

Further, on the lower side of the transport device 1, a drying device 16 for drying the ink of the tablet after printing is provided. More specifically, the drying device 16 is a region in which the transport belt 13 advances from the second pulley 12 to the first pulley 11 (located between the reference numerals E and F in FIG. 1 and is horizontal on the lower side of the transport device 1). It is provided at a position facing the portion). That is, the drying device 16 is provided at a position facing the transport belt 13, and for example, the ink printed on the tablet is dried by blowing hot air on the tablet.

Regarding the placement position of the drying device 16, any position can be used as long as the ink printed on the tablet can be dried without interfering with other mechanisms constituting the tablet printing device S. good.

As shown in FIG. 1, the first transport device 1 is arranged in the upper portion of the tablet printing device S, and the second transport device 2 is arranged in the lower portion thereof. The second transport device 2 prints the tablet printed on one side by the first printing unit 3 on the other side of the tablet by the second printing unit 4 provided on the upper side of the tablet. It is a device that conveys tablets for this purpose.

As described above, the second transfer device 2 is basically the same as the first transfer device 1. That is, the second transfer device 2 includes a first pulley 21, a second pulley 22, an endless transfer belt 23, and a suction chamber 24.

The first pulley 21 is the right pulley of the two pulleys shown in a circular shape on the second transport device 2 in FIG. The second pulley 22 is the left pulley of the above-mentioned two pulleys in FIG.

The transport belt 23 transports tablets by rotating the first pulley 21 and the second pulley 22. Further, the transport belt 23 is formed with suction holes for sucking tablets on the belt surface.

The suction chamber 24 applies a suction force to the suction holes of the transport belt 23. When the suction chamber 24 sucks air, the tablets are sucked and held by the transport belt 23 through the suction holes. Since the suction chamber 24 has such a function, the suction chamber 24 is configured to be able to apply a suction force to the suction holes at any position on the entire circumference of the transport belt 23.

The second transfer device 2 adopts the above-described configuration, and both the first pulley 21 and the second pulley 22 rotate counterclockwise. Therefore, in the second transfer device 2, the transfer belt 23 moves to the left in the direction of the arrow indicated by the solid line in the upper horizontal region, that is, from the first pulley 21 to the second pulley 22. ..

A second printing unit 4 is provided on the upper side of the second transfer device 2 at a position facing the surface of the transfer belt 23 that advances from the first pulley 21 to the second pulley 22. .. Therefore, when printing a tablet in the second printing unit 4, the tablet is placed on the transport belt 23 and transported below the second printing unit 2.

The second printing unit 4 includes an inkjet printing unit 41 that prints on tablets, a position detecting device 42 provided on the upstream side of the transport belt 23 in the traveling direction of the inkjet head 411 included in the inkjet printing unit 41, and an inkjet head 411. It has a print state confirmation device 43 provided on the downstream side in the traveling direction of the transfer belt 23.

The position detection device 42 includes a photographing device 421 for photographing a tablet and an illumination 422 for illuminating the tablet to be photographed. Further, the print state confirmation device 43 is composed of a photographing device 431 for photographing the printed state of the tablet and an illumination 432 for illuminating the tablet to be photographed.

The roles and functions of the inkjet printing unit 41, the position detecting device 42, and the printing state confirmation device 43 here are the same as those of the components of the first printing unit 3 described above.

Further, on the lower side of the transport device 2, a drying device 25 for drying the ink of the tablet after printing is provided. More specifically, the drying device 25 is a region in which the transport belt 23 advances from the second pulley 22 to the first pulley 21 (located between the reference numerals I and J in FIG. 1 and is horizontal on the lower side in the transport device 2). It is provided at a position facing the portion).

As for the arrangement position of the drying device 25, the ink printed on the tablet can be dried without interfering with other mechanisms constituting the tablet printing device S, as in the arrangement position of the drying device 16 described above. If there is, it may be arranged at any position.

Boxes 26 and 27 are provided at positions on the downstream side of the drying device 25 in the second transport device 2 to collect tablets that have been printed on the surfaces of both the upper and lower surfaces according to the quality of printing. Based on the confirmation results from the print state confirmation device 33 and the print state confirmation device 43, the control unit 5 determines the quality of printing for each tablet.

For example, if it is determined that the printing condition is appropriate, the tablets are sent from the transport belt 23 to the non-defective product collection box 26. On the other hand, when it is determined that the printing state is inappropriate, the tablets are sent as defective products from the transport belt 23 to the defective product collection box 27. As an example of the defective product collection means, the tablets can be stored in the defective product collection box 27 by blowing air on the tablets while falling from the transport belt 23 to the non-defective product collection box 26.

(Printing operation)
Next, a printing operation for performing a printing process on a tablet using the tablet printing device S using FIG. 1 will be described step by step.

First, the tablets stored in the hopper 15 are supplied toward the first pulley 11 of the first transport device 1 that rotates clockwise.

The tablet is supplied from the hopper 15 at the position as shown in FIG. 1, but a suction force is applied to the suction hole from the suction chamber 14, and the tablet is sucked and held by the transport belt 13 without falling.

The tablet is conveyed while being attracted to and held by the transfer belt 13 by the suction chamber 14, and characters, figures, etc. are printed on the upper surface of the tablet by the first printing unit 3 provided on the upper side of the first transfer device 1. Will be done. Characters, figures, etc. are set in advance.

Specifically, first, the position detection device 32 confirms the position and orientation of the tablet on the transport belt 13. Specifically, the image of the tablet taken by the photographing device 321 of the position detecting device 32 is transmitted to the control unit 5, and the position, posture, and printability are determined.

The posture is a case where it is necessary to determine the printing direction because the tablet transport belt 13 is tilted with respect to the belt surface, the tablet is provided with a dividing line, or the outer shape is elliptical or rectangular. It is suitable.

If it is determined that printing is not possible, processing such as passing under the first printing unit 3 as it is is performed without printing. On the other hand, when the position of the tablet is held in a printable position or posture, the tablet is directly conveyed under the inkjet printing unit 31 by the conveying belt 13.

The inkjet head 311 prints on the upper surface of the conveyed tablet. When printing is completed, the tablets are conveyed as they are, and then moved to the bottom of the printing state confirmation device 33.

The print state confirmation device 33 photographs the conveyed tablet and transmits the captured image to the control unit 5. The control unit 5 determines whether the print state is good or bad based on the information sent from the print state confirmation device 33.

After that, the tablet is inverted by the second pulley 12 while being sucked and held by the transport belt 13, and moves from the upper side to the lower side of the first transport device 1.

A drying device 16 is provided while the transport belt 13 moves from the second pulley 12 to the first pulley 11 to the left in FIG. Since the printed surface of the tablet moving to the left faces the drying device 16, the ink adhering to one side of the tablet is dried by the drying device 16.

Further, on the downstream side of the drying device 16, the transport belt 13 faces the transport belt 23 of the second transport device 2. The first pulley 21 and the second pulley 22 in the second transfer device 2 are rotating counterclockwise. Therefore, the transport belt 23 hung on these pulleys rotates to the left. That is, the transport belt 23 moves to the left in FIG. 1 in the upper horizontal region.

Therefore, in the region where the transport belt 13 of the first transport device 1 meets the transport belt 23 of the second transport device 2, both move in the same direction, that is, to the left in FIG.

Here, the first pulley 11 of the first transfer device 1 and the first pulley 21 of the second transfer device 2 are aligned so that their axes coincide with each other in the vertical direction. Therefore, the tablet is at the position F where the transfer belt 13 comes into contact with the first pulley 11 of the first transfer device 1 and at the position F where the transfer belt 23 is separated from the first pulley 21 of the second transfer device 2. Is handed over.

However, the positional relationship between the first pulley 11 of the first transfer device 1 and the first pulley 21 of the second transfer device 2 is not fixed to the positional relationship as in the first embodiment. However, the positions of the two may be displaced within the range in which the tablets can be delivered.

When the transfer belt 23 is viewed from above, the tablet transferred from the first transfer device 1 to the second transfer device 2 has the surface printed by the first printing unit 3 on the surface of the transfer belt 23. It is attracted to and held by the transport belt 23 in a state where the surface facing the opposite side can be seen.

In the second transport device 2, printing is performed on one side of the tablet that has not been printed. The printing flow is the same as described above. After the position and orientation of the tablet are confirmed by the position detecting device 42 and printing is performed by the inkjet head 411, the printing state confirmation device 43 is used as the basis for printing. The print status is confirmed.

In the printed tablet, the ink is dried by the drying device 25 in the lower horizontal region of the second transport device 2. In this case, one side of the tablet printed by the second printing unit 4 faces the drying device 25, and while the transport belt 23 moves from the second pulley 22 toward the first pulley 21. The ink is dried.

The dried tablets are stored in collection boxes 26 and 27 and collected. That is, the tablets determined by the control unit 5 that printing has been appropriately performed based on the confirmation results from the print state confirmation device 33 and the print state confirmation device 43 are stored in the non-defective product collection box 26. On the other hand, the tablet determined by the control unit 5 to be improperly printed is collected by the defective product collection box 27. In the first embodiment, tablets determined not to be printed based on the detection results of the position detection devices 32 and 42 are also sent to the defective product collection box 27.

(Printing department)
Next, the printing unit P according to the first embodiment will be described. As described above, since the first printing unit 3 and the second printing unit 4 constituting the printing unit P adopt substantially the same configuration, the first printing unit 3 is also used as an example here. Will be described below.

FIG. 2 is a configuration diagram showing a configuration of an inkjet printing unit 31 of the first printing unit 3 according to the first embodiment of the present invention.

As shown in FIG. 2, the inkjet printing unit 31 includes an inkjet head 311 located facing the tablet on the transport belt 23. The inkjet head 311 includes a nozzle N, and printing is performed on a tablet by ejecting ink from the nozzle N. Ink is also ejected from the nozzle N when maintenance processing such as purging or dummy ejection is performed.

An ink supply tube 34 for receiving the ink supply from the ink bottle B is connected to the inkjet head 311. That is, one end of the ink supply tube 34 is connected to the inkjet head 311 via the ink supply port IN of the inkjet head 311 and the other end is connected to the ink bottle B. As the ink supply tube 34, for example, a tube having flexibility can be preferably used.

Further, in general, a valve is provided in the middle of the ink supply pipe 34 so that the ink can be supplied from the ink bottle B to the inkjet head 311 or the supply can be stopped. However, in the first embodiment, such a valve is not provided.

The ink bottle B is a bottle that houses ink used in a printing process or a maintenance process (hereinafter collectively referred to as a printing process or the like). The ink bottle B contains, for example, an amount of ink that is used in a printing process for one day and can be used up without replenishment.

In addition, in the tablet printing apparatus S according to the first embodiment, printing is also performed on a tablet that a person puts in the mouth. Therefore, for example, in order to prevent various foreign substances from being mixed into the ink or the ink itself from deteriorating, it is desirable to use up the ink in, for example, a day's printing process. Further, in some cases, by replenishing the ink bottle B with ink from another tank or the like, it becomes easy for foreign matter to be mixed into the ink in the ink bottle B, and it becomes difficult to manage the expiration date. Therefore, it is desirable to use up the ink bottle B.

Therefore, the ink bottle B in the first embodiment contains, for example, an amount of ink that can be used up in a day's printing process or the like, or an amount that allows an extra error or the like to be used up. Ink is stored.

Therefore, for example, a new ink bottle B is prepared before the printing process or the like is started, and the amount of ink required for the printing process or the like is used. Then, when the printing process for one day is completed, the ink bottle B will be replaced even if the ink remains. The replaced ink bottle B can be reused by cleaning it. If cleaning is difficult, the ink bottle B can be disposable.

At this time, not only the ink bottle B but also the ink supply pipe 34 is replaced. This is because the ink itself remaining in the ink supply pipe 34 is always used up. Therefore, if there is an on-off valve in the ink supply pipe 34, the on-off valve and the on-off valve are replaced together.

That is, the on-off valve is also discarded every time the ink is replaced, which increases the running cost. Further, when the on-off valve is cleaned and reused, it is necessary to confirm whether the cleaning has been performed reliably, and the running cost will also increase by such a cleaning and cleaning confirmation process.

A tube B1 is connected to the upper part of the ink bottle B, and a valve B2 is provided in the tube B1. These tubes B1 and valve B2 are used when the inside of the ink bottle B is opened to the atmosphere.

Further, a tube 351 connected to a pressurizing device (not shown) for applying pressure to the ink contained in the ink bottle B is also connected to the upper portion of the ink bottle B. A valve 352 is provided in the middle of the pipe 351 connecting the ink bottle B and the pressurizing device, and the valve 352 is opened and closed according to the pressurizing process.

The opening and closing of both the valve B2 and the valve 352 may be controlled manually or based on an instruction from the control unit 5.

The ink bottle B is placed on a moving device 36 for maintaining the height L2 of the liquid level L of the ink contained in the ink bottle B at a predetermined height. The moving device 36 includes a mounting table 361 on which the ink bottle B is placed, a moving mechanism 362 for moving the mounting table 361, and a driving device 363 for driving the moving mechanism 362.

Although not particularly shown in FIG. 2, for example, an instrument, a device, or the like for preventing the ink bottle B placed on the mounting table 361 from tipping over may be provided.

The mounting table 361 moves in the Z-axis direction shown in FIG. 2 when the moving mechanism 362 is driven by the driving force from the driving device 363. By moving the mounting table 361 in the Z-axis direction in this way, the ink bottle B also moves.

Here, as the moving mechanism 362, various mechanisms can be adopted as long as the ink bottle B can be moved in the Z-axis direction, such as a ball screw.

The driving device 363 applies a driving force to the moving mechanism 362 to move the ink bottle B in the Z-axis direction. The drive device 363 is electrically connected to the control unit 5 shown in FIG. 1, and drives the movement mechanism 362 based on the control signal from the control unit 5.

As the drive device 363, for example, when the moving mechanism 362 employs a ball screw, a motor or the like that rotates the ball screw can be adopted. However, any device may be adopted as long as it is possible to provide a driving force capable of moving the mounting table 361 (ink bottle B) in the Z-axis direction by the moving mechanism 362.

A discharge pipe 37 is connected to the inkjet head 311. A valve 371 is provided in the middle of the discharge pipe 37. The opening and closing of this valve 371 is also controlled manually or based on an instruction from the control unit 5.

One end of the discharge pipe 37 is connected to the inkjet head 311 via the ink discharge port OUT of the inkjet head 311 and the other end is connected to the discharge bottle BE that receives the discharged ink. Then, the height of the other end of the discharge pipe 37, that is, the height of the end surface of the discharge pipe 37 on the discharge bottle BE side is set to be lower than the liquid level L in the ink bottle B.

In the first embodiment, it is premised that the ink contained in the ink bottle B is used up in, for example, a printing process for one day. Therefore, the ink remaining in the inkjet head 311 is not returned to the ink bottle B, and when the printing process or the like is completed, the ink in the inkjet head 311 is drained from the drain pipe 37. That is, the ink remaining in the inkjet head 311 or in the pipe is discharged to the discharge bottle BE. A pipe B3 that opens the inside of the discharge bottle BE to the atmosphere is connected to the upper part of the discharge bottle BE.

As the discharge pipe 37, for example, a flexible pipe can be preferably used.

Further, in the middle of the discharge pipe 37, a sensor KE for observing the color and turbidity of the liquid flowing through the discharge pipe 37 is provided.

As will be described later, this sensor KE detects whether or not the ink has reached the discharge pipe 37 when, for example, the ink bottle B is replaced and the ink is filled in the inkjet head 311 or the pipe in preparation for printing. When it is detected that the filling is completed or the inside of the inkjet head 311 or the inside of the pipe is cleaned, the cleaning liquid such as pure water is mixed with the ink and is colored or turbid. This is for detecting that the cleaning is completed.

Conventionally, the completion of such cleaning has been judged visually or by time, etc., but the cleaning condition also varies due to the influence of the ink concentration and the solubility in the cleaning liquid. In addition, there were variations in the judgment visually. In this regard, by detecting the transparency and turbidity of the pipe or the liquid in the pipe with the sensor KE as described above, the variation in the determination of the completion of cleaning can be suppressed.

It should be noted that such detection can be performed depending on the absorbance, transmittance, reflection state, etc. of the detection target, and any sensor that can detect such a state can be applied. Further, the transparency and the turbid state may be detected by imaging with a camera or the like.

As described above, the ink bottle B contains ink used in printing processing and the like. Then, in order to enable the ink to be ejected from the inkjet head 311 in the printing process or the like, the ink is supplied from the ink bottle B to the inkjet head 311 through the ink supply tube 34. It is necessary to maintain a predetermined head difference so that ink can be appropriately supplied from the ink bottle B to the inkjet head 311.

(Head difference)
In the first embodiment, as shown in FIG. 2, the height L1 of the nozzle forming surface 312 on which the nozzle N of the inkjet head 311 is formed and the height of the liquid level L of the ink contained in the ink bottle B The difference from L2 is the head difference to be controlled, and the above-mentioned defined head difference that needs to be maintained. In FIG. 2, it is indicated by reference numeral h1 (head difference on the supply side). The water head difference h1 is set so that the height L2 of the liquid level L of the ink in the ink bottle B is lowered with reference to the height L1 of the nozzle forming surface 312 of the inkjet head 311 during the printing process. Therefore, also in FIG. 2, it is shown that the height of the liquid level L in the ink bottle B is lower than the height of the nozzle forming surface 312.

The h1 of the water head difference is for generating a negative pressure in the inkjet head 311, and in relation to the surface tension M due to the meniscus of the ink generated in the nozzle N of the inkjet head 311. The outside air will enter the head 311 and if the negative pressure is small, the ink will leak from the nozzle N. Therefore, after the inkjet head 311 is filled with ink, the water head difference (predetermined water head difference) is maintained so that the outside air does not enter from the nozzle N and the ink does not leak out.

Further, if the change in h1 of the head difference is large during the printing process, the amount of ink ejected from the nozzle N also changes significantly. When printing on a tablet in the tablet printing apparatus S, since the amount of ink used for printing is very small, if the amount of ink ejected changes significantly, printing faintness or bleeding will occur. Therefore, printing on tablets is not performed properly. Therefore, in order to stabilize the amount of ejected ink, h1 of the head difference is maintained at a predetermined value at least during the printing process.

The height L2 of the ink liquid level L in the ink bottle B (hereinafter referred to as the height L2 of the ink liquid level L) is the height L3 from the reference surface to the bottom surface of the ink bottle B and the bottom surface of the ink bottle B. It is the sum of the height from the ink to the liquid level L of the ink in the ink bottle B. The reference surface is, for example, the upper surface of a common base such as a base plate in the first printing unit 3. A drive device 363 and the like are mounted on the upper surface.

The predetermined value of h1 of the head difference is determined within a predetermined allowable range having a width of the head difference suitable for printing on tablets. Specifically, the head difference h1, which is the difference between the height L1 of the nozzle forming surface 312 of the inkjet head 311 and the height L2 of the ink liquid surface in the ink tank B, is, for example, between -5 mm and +5 mm. Is set within a predetermined allowable range that is allowed with a certain width. Regarding h1 and its range of the head difference that can be tolerated for use in printing processing, etc., the flow path configuration and shape in the inkjet head 311, the cross-sectional shape and hole diameter of the nozzle N, the composition of the ink used, the viscosity and the specific gravity, etc. Since it is affected by the characteristics of the ink, the loss on the flow path, etc., it is determined by experiments. Further, the h1 of the head difference is required to be within a certain range, but this range also differs depending on the above-mentioned conditions of the inkjet head 311.

Further, the inkjet head 311 maintains the head difference h1 between the height L1 of the nozzle forming surface 312 on which the nozzle N is formed and the height L2 of the liquid surface L of the ink in the ink bottle B. The inkjet head 311 does not move. Of course, the inkjet head 311 may move in order to adjust the ink ejection distance from the tablet to be printed, but the inkjet head 311 does not move in maintaining the water head difference h1. As a result, the distance between the tablet and the inkjet head 311 does not fluctuate during printing, and the reach of the ejected ink to reach the tablet is constant. Therefore, even when printing on a small tablet, clean printing can be performed. it can.

(How to maintain the head difference during printing)
In the first embodiment, h1 of the head difference is maintained as constant as possible at least during the printing process.

Therefore, a method of maintaining the head difference h1 at a predetermined value during a printing process or the like will be described below while appropriately using drawings.

FIG. 3 is a flowchart showing the flow of tablet printing according to the first embodiment. Here, for example, the flow of printing processing on tablets in one day is shown.

As shown in FIG. 3, first, when starting the printing process or the like, the ink bottle B is placed on the mounting table 361 (ST1).

An ink supply pipe 34 is connected to the ink bottle B mounted on the mounting table 361 so that the ink can be supplied to the inkjet head 311. Further, the tube 351 connected to the pressurizing device is also connected to the upper part of the ink bottle B. Further, a tube B1 provided with a valve B2 is also connected to the upper portion of the ink bottle B.

When the ink bottle B is ready, the inkjet head 311 is then filled with ink (ST2). In this ink filling process, first, the valve 352 provided in the pipe 351 connecting the pressurizing device and the ink bottle B and the valve 371 provided in the discharge pipe 37 are opened. At this time, the valve B2 is closed. Then, pressure is applied to the ink in the ink bottle B using a pressurizing device.

In response to this pressure application, the ink in the ink bottle B is filled in the inkjet head 311 through the ink supply tube 34. When the ink is filled in the inkjet head 311, the ink overflowing from the inside of the inkjet head 311 after that is discharged to the outside of the inkjet head 311 via the discharge pipe 37.

While the filling process is being performed, the control unit 5 checks at any time whether or not the inside of the inkjet head 311 is filled with ink, that is, whether or not the ink filling process is completed (ST3). This indicates that when the ink reaches the discharge pipe 37, the flow path in the inkjet head 311 (indicated by the broken line in the inkjet head 311 in FIG. 2) is filled with the ink, and it is determined that the filling process is completed. can do. Therefore, for example, the filling process is completed by detecting whether or not there is ink in the discharge pipe 37 or detecting the discharge of ink from the discharge pipe 37 by the sensor KE provided in the discharge pipe 37. It can be regarded (YES in ST3). When it is determined that the filling operation is completed, the valve 371 of the discharge pipe 37 is closed.

Although the filling process has been described here with an example of using a pressurizing device, for example, the liquid level in the ink bottle B itself is at least higher than the nozzle forming surface 312. It is also possible to carry out the filling process by raising the amount to. Of course, purging treatment and cleaning treatment can also be performed using these methods.

Next, whether or not the control unit 5 needs to adjust the head difference in relation to the height L1 of the nozzle forming surface 312 of the inkjet head 311 and the height L2 of the liquid level L of the ink in the ink bottle B. Confirm (ST4).

Here, as shown in FIG. 2, the sensor K is installed in the moving path of the mounting table 361 of the moving mechanism 362. This sensor K is for detecting the height L2 of the ink liquid level in the ink bottle B. Therefore, it suffices if the liquid level L can be detected, and it may be provided in addition to the moving mechanism 362. The height L4 at which the sensor K detects the liquid level L is such that the height L2 of the ink liquid level in the ink bottle B is lower than the height at which the head difference h1 becomes a predetermined value.

The control unit 5 confirms whether or not the liquid level L in the ink bottle B is detected by the sensor K when the filling process is completed. If the liquid level is not detected by the sensor K (YES in ST4), the control unit 5 controls the mounting table 361 to move up or down in the Z direction until it is detected. For example, if the liquid level is not detected even if the mounting table 361 is raised for a preset distance or time, the mounting table 361 is lowered. When the sensor K detects the liquid level, the control unit 5 stops the mounting table 361. At this time, the installation height (liquid level detection height) L4 of the sensor K becomes the height L2 of the ink liquid level in the ink bottle B. That is, it is possible to calculate the predetermined value h1 in head differential between (a predetermined water head difference), and the water head difference is calculated from the height L2 of the ink surface of the current, the difference of. The control unit 5 drives the mounting table 361 so that this difference becomes zero. As a result, the height L2 of the ink liquid level in the ink bottle B is adjusted to a height at which the head difference h1 becomes a predetermined value (ST5).

As described above, the valve 371 of the discharge pipe 37 is closed when the filling process is completed. Then, in order to start ejecting ink from the inkjet head 311, the valve 352 provided in the tube 351 connecting the pressurizing device and the ink bottle B is further closed. On the other hand, in the filling process, the valve B2 provided on the upper part of the closed ink bottle B is opened and opened to the atmosphere. In this state, ink is supplied from the ink bottle B to the inkjet head 311 so that the ink can be ejected, and the tablet printing apparatus S starts ejecting the ink from the nozzle N to the tablet (ST6).

It is better not to release to the atmosphere when the filling process is completed. By continuing to pressurize the inside of the ink tank B, it is possible to prevent the ink from returning from the inkjet head 311 to the ink tank B even if the liquid level of the ink in the ink tank B drops too much.

Here, regarding the amount of ink consumed, for example, it is possible to grasp in advance the amount of ink consumed by the daily printing process or the like. For example, the number of tablets to be printed in a daily printing process or the like is predetermined. The amount of ink used for one tablet is also predetermined from the printed content of the tablet. From this information, for example, the amount of ink consumed by the daily printing process or the like can be grasped. Then, it becomes possible to grasp the amount of ink consumed per number of tablets printed or per unit time of the printing process.

The number of such prints and the amount of ink consumed per unit time are, that is, the amount of ink consumed from the inside of the ink bottle B. Since the inner diameter of the ink bottle B can be grasped in advance, as a result, it is possible to grasp the number of prints and the change in the height of the liquid level L in the ink bottle B per unit time. Therefore, it is possible to grasp the change in the number of prints and the change in the head difference h1 per unit time.

FIG. 4 is a diagram showing a state in which the ink in the ink bottle B shown in FIG. 2 is consumed and the ink tank B is raised. Therefore, there is no change in the configuration of FIG. 2 used when explaining the configuration of the first printing unit 3, but the height L3 of the ink bottle B is different.

FIG. 2 shows a state in which the new ink bottle B is placed on the mounting table 361 as described in step ST1 of FIG. Therefore, the ink is sufficiently contained in the ink bottle B, and the height L3 of the ink bottle B is set so that the head difference h1 becomes a predetermined value according to the height L2 of the liquid level L at that time. The positioned state is shown.

On the other hand, FIG. 4 shows a state in which the height of the liquid level L in the ink bottle B is lowered due to the use of the ink in the ink bottle B due to the progress of the printing process and the ejection of the ink from the nozzle N. There is. Then, the liquid level L of the ink in the lowered ink tank B is moved upward by using the moving device 36, and the state where the head difference h1 is positioned to be a predetermined value is shown. Has been done. That is, it is shown that even if the printing process progresses and the ink is consumed, the head difference h1 is maintained at a predetermined value.

As shown in step ST7 of FIG. 3, the state of the decrease in the liquid level L in the ink bottle B in the number of prints and the unit time is predicted from the amount of ink used in the printing process or the like that is grasped in advance. Can be done. Therefore, by moving the ink bottle B itself upward in accordance with the predicted state of the decrease in the liquid level L, the change in the height of the liquid level L, that is, the height L2 of the ink liquid level is canceled out, and the head difference is increased. Keep h1 at a predetermined value.

By grasping the change in the height of the ink liquid level L in the ink bottle B in advance in this way, the ink is consumed by the printing process or the like, and the liquid level L in the ink bottle B gradually decreases. Te can be Rukoto so as not to change the height L2 of the ink surface in the ink bottle B to maintain the h1 water head difference to a predetermined value. For example, the mounting table 361 is controlled to be raised by the change in the height of the liquid level L in the ink bottle B described above for each predetermined number of tablets or for each predetermined unit time.

Moreover, instead of simply changing the height of the ink bottle B, the ink liquid in the ink bottle B is used by utilizing the information on the change in the height of the ink liquid level L in the ink bottle B that is grasped in advance. It is possible to move the ink bottle B so as to maintain the height of the surface L as unchanged as possible.

As described above, the ink bottle B is such that the height of the liquid level L in the ink bottle B maintains the head difference h1 based on the information regarding the amount of ink consumed in the unit time that is grasped in advance. Ink can be stably supplied to the inkjet head 311 by controlling the height of the ink to be gradually changed.

After the above-mentioned step ST5, when the ink ejection is started from the nozzle N of the inkjet head 311 by a printing process or the like, the ink bottle B is moved upward according to the amount of ink used which is known in advance. The control unit 5 controls the drive device 363 of the mobile device 36 (ST7).

At this time, the amount of ink consumed is grasped in advance, and based on the information on the amount of ink, the amount of ink contained is reduced by using the ink for printing processing or the like, and the inside of the ink bottle B Even if the height of the liquid level L becomes low, the moving device 36 is used to control the movement of the ink bottle B upward so that the height L3 of the ink bottle B becomes high according to the change. .. As a result, even if the ink in the ink bottle B is used by the printing process or the like and the height of the liquid level L is lowered, the head difference h1 can always be maintained at a predetermined value.

The control unit 5 determines at any time whether or not the printing process or the like is completed (ST8). For example, the control unit 5 determines that the printing process or the like is completed when the supply of tablets from the hopper 15 is completed or when the operator presses an operation button. The control unit 5 instructs the moving device 36 to finish moving the ink bottle B when the tablet printing device S finishes printing the tablet.

When the printing process or the like is completed, the ink bottle B used so far is removed from the mounting table 361, and the mounting table 361 moves downward again to prepare for the next ink bottle B to be placed (). ST9). Regarding the downward movement of the mounting table 361, the control unit 5 takes into consideration the height of the liquid level L of the ink (h1 of the head difference) in the ink bottle B for storing the ink to be used next. The moving distance is instructed to the drive device 363.

As described above, according to the first embodiment, it is possible to grasp the number of prints and the amount of ink consumed per unit time by grasping the amount of ink used in advance. Therefore, by adjusting the height of the ink bottle B itself based on the consumption amount, when the ink is supplied from the ink bottle to the inkjet head 311, the nozzle forming surface 312 of the set inkjet head 311 It is possible to maintain h1 of the water head difference between the height L1 and the height L2 of the liquid level L of the ink in the ink bottle B at a predetermined value. As a result, the amount of ink ejected from the inkjet head 311 can be stabilized, and printing on tablets can be performed satisfactorily. Therefore, it is possible to provide a tablet printing apparatus and a tablet printing method capable of appropriately printing on a small printing object such as a tablet.

Further, in printing on a small tablet, a slight change in h1 of the head difference appears as a large change in the amount of ink to be ejected. In the first embodiment, since the head difference h1 can be maintained at a predetermined value in almost real time, there is no significant change in the amount of ink ejected, and printing on tablets can be performed without causing faintness or bleeding of printing. It is done properly.

Further, in the first embodiment, the inkjet head 311 is not moved in order to maintain the head difference h1. That is, the inkjet head 311 is fixed during printing on the tablet. Therefore, the distance between the tablet and the inkjet head 311 is the optimum distance for printing, and the distance does not change. Therefore, the distance from the ink ejection to the tablet is constant, and even printing on a small tablet can be performed beautifully.

By the way, depending on the components of the ink, the composition portion thereof may aggregate in the ink to form an agglomerate. The presence of such agglomerates increases resistance in the flow path in the inkjet head 311 and impedes the flow of ink. Further, if the size of the aggregate is larger than the nozzle diameter of the inkjet head 311, the nozzle N may be clogged and ejection may not be possible.

The agglomerates that have agglomerated in the ink bottle B can be filtered out so as not to reach the inkjet head 311 by providing the filter F on the ink supply tube 34. (See Fig. 8)
For example, when the size of the agglomerates is about 15 μm to 30 μm, it affects the ejection of ink. Therefore, it is advisable to prevent agglomerates of 10 μm or more from passing through the filter.

However, agglomeration may proceed even during the printing process, and agglomerates may be generated and grow in the supply tube 34 and the inkjet head 311. It is necessary to remove it from the inside of the head 311. That is, the ejection process for ejecting the ink in the inkjet head 311 is performed periodically while the size of the agglomerates does not affect the ejection.

Therefore, the time (discharge interval time) at which the size of the agglomerates grows to a size that affects the ejection for each type of ink used in advance is obtained by an experiment or the like and stored in the control unit 5. Such a discharge interval time is, for example, about 1 minute to 30 minutes.

At the same time that the printing process by the inkjet head 311 is started, the control unit 5 starts counting the printing processing time (printing time). When the discharge interval time is reached, the printing process is stopped. Next, the valve 371 of the discharge pipe 37 is opened. As a result, the ink in the supply pipe 34 and the inkjet head 311 is discharged via the discharge pipe 37.

As described above, one end of the discharge pipe 37 is connected to the discharge port OUT of the inkjet head 311 and the other end is installed so as to be below the liquid level L of the ink in the ink bottle B.

Therefore, the ink in the inkjet head 311 is discharged due to the head difference of the ink in the ink bottle B from the liquid level L.

The control unit 5 keeps time when a predetermined time elapses from the start of ink discharge, and closes the valve 371 when the predetermined time is discharged. This predetermined time may be at least a time for the ink between the ink supply port IN and the ink discharge port OUT of the inkjet head 311 to move from the ink discharge port OUT into the discharge pipe 37. More preferably, it is sufficient that the time is sufficient to move the ink in the ink supply pipe 34 into the ink discharge pipe 37. Further, as shown in FIG. 8 described later, when the filter F is provided in the ink supply tube 34, the ink in the ink supply tube 34 on the inkjet head 311 side of the filter F is in the ink discharge tube 37. It may be just time to move to. That is, the ink discharge in the inkjet head 311 includes the ink in the ink supply tube 34.

Specifically, as shown in FIG. 5, while the printing process (ST10) is being performed, the control unit 5 measures the elapsed time until the agglomerates are discharged (ST11). When this elapsed time reaches the discharge interval time, that is, when the printing time elapses for a predetermined time, the printing process is stopped (ST12) and the valve 371 of the discharge pipe 37 is opened (ST13). Then, the ink in the discharge pipe 37 flows into the discharge bottle BE due to the differential pressure due to h2, which is the water head difference from the liquid level L in the ink bottle B to the end face on the discharge bottle BE side of the discharge pipe 37, so that the discharge process is performed. It is done (ST14). Therefore, the ink in the inkjet head 311 and the ink supply tube 34 also flows toward the discharge bottle BE.

When this discharge process is started, the control unit 5 measures the discharge time (discharge time). Then, after a predetermined discharge time, for example, a time for ink to flow from the supply port IN to the discharge port OUT of the inkjet head 311 confirmed in advance by an experiment or the like has elapsed, the valve 371 is closed to end the discharge process. (ST15, ST16). When the ejection process is completed, the printing process is restarted (ST17).

In order to perform the discharge process, as shown in FIG. 2, the height (head difference) of the ink in the ink bottle B to the liquid level L is set with reference to the nozzle forming surface 312 for ejecting the ink of the inkjet head 311. h1 (water head difference on the supply side), the height (water head difference) from the liquid level L of the ink in the ink bottle B to the discharge side end face of the discharge pipe 37 is h2, and the discharge side end face of the discharge pipe 37 from the nozzle forming surface 312. When the height up to (head difference) is h3 (head difference on the discharge side), each height (head difference) is arranged so as to have the following relationship. For ease of understanding, the illustration of each head difference in the figure is exaggerated.

In the first embodiment, the end face of the ink supply tube 34 on the ink bottle B side is arranged so as to be located in the ink in the ink bottle B. Further, the discharge side end surface of the discharge pipe 37 is arranged so as to be located on the drain surface in the discharge bottle BE.

Then, at least during the printing process, the liquid level L of the ink in the ink bottle B is located at the same level as the nozzle forming surface 312 of the inkjet head 311 or below the nozzle forming surface 312. Further, the discharge side end surface of the discharge pipe 37 is located below the nozzle forming surface 312 of the inkjet head 311 and below the liquid level L of the ink in the ink bottle B. Therefore, h1 of the head difference and h3 of the head difference are larger than h1 (h3> h1).

Therefore, h1 of the head difference from the nozzle forming surface 312 of the inkjet head 311 to the liquid level L in the ink bottle B, and h2 of the water head difference from the liquid level L of the ink in the ink bottle B to the discharge side end face of the discharge pipe 37. The relationship of h3 of the head difference from the nozzle forming surface 312 of the inkjet head 311 to the discharge side end surface of the discharge pipe 37 is that h2 of the head difference is the difference between h3 and h1 of the head difference, and h2 = h3-h1. Become.

Further, by the above-mentioned filling process, the inside of the ink supply pipe 34, the inside of the inkjet head 311 and the inside of the discharge pipe 37 are filled with ink, and then the valve 371 of the discharge pipe 37 is closed, so that the filling process is completed. In the state, the nozzle forming surface 312 of the inkjet head 311 is subjected to the back pressure generated by h1, which is the head difference from the liquid level L in the ink bottle B.

By the way, a surface tension M is generated on the liquid surface (meniscus) in each nozzle of the nozzle forming surface 312 of the inkjet head 311, and the surface tension M and the pressure P in the inkjet head 311 (the inkjet head 311 in FIG. 2). Depending on the relationship (pressure in the flow path shown by the broken line), ink may drip from the nozzle N or outside air may be sucked into the inkjet head 311. That is, when the pressure P becomes a positive pressure and becomes larger than the surface tension M, ink drips from the nozzle N, and when the pressure P becomes a negative pressure and becomes larger than the surface tension M, the outside air is sucked into the inkjet head 311 through the nozzle N. As a result, air bubbles may be generated in the inkjet head 311.

Therefore, the head difference is adjusted so that the surface tension M and the pressure P (back pressure) are about the same.

The pressure P in the inkjet head 311 becomes a positive pressure when the liquid level L in the ink bottle B is located (higher) above the nozzle forming surface 312. Then, let α be the head difference at which the pressure P becomes the pressure at which the ink drips from the nozzle N.

Further, let β be the head difference at which the pressure P becomes the negative pressure in which the ink is drawn into the inkjet head 311 from the nozzle N of the inkjet head 311 and the outside air invades.

The α and β of these head differences are not zero. Therefore, the relationship between the surface tension M and the pressure P (back pressure) has a width from the state where the ink does not drip from the nozzle N to the time when the outside air is drawn from the nozzle N. This width is (α + β) in absolute value.

In the first embodiment, the back pressure in the inkjet head 311 is always a negative pressure, and the height of the liquid level L of the ink in the ink bottle B is set to be the height of the inkjet head 311 in order to simplify the control of ink ejection. The printing process is performed so as not to be higher than the nozzle forming surface 312. Therefore, α = 0 can be set, and the width from the state where the ink does not drip from the nozzle N to the drawing of outside air from the nozzle N can be simply β. That is, during the printing process, the back pressure (pressure P) in the inkjet head 311 is controlled so that the head difference h1 is set within β, the ink does not drip from the nozzle N, and the outside air is not sucked in. Will be done.

When performing the discharge process, the valve 371 of the discharge pipe 37 is opened. Then, since h3 and h1 of the head difference are set in the relationship of h3> h1, the difference due to h2, which is the head difference from the liquid level L in the ink bottle B to the end face of the discharge pipe 37 on the discharge bottle BE side. Due to the pressure, the ink in the discharge pipe 37 flows into the discharge bottle BE.

By this flow, the agglomerates in the inkjet head 311 and in the ink supply pipe 34 and the discharge pipe 37 can be discharged from the inkjet head 311 together with the ink.

At this time, in order that the ink does not drip from the nozzle N and the outside air is not drawn in, the pressure P in the inkjet head 311 needs to be smaller than the pressure due to the head difference at β as described above. is there.

That is, it is necessary that both h1 and h3 of the head difference are within β of the head difference. That is, (h1 <β, h3 <β).

As described above, in the first embodiment, h1 has a height at which the inside of the inkjet head 311 of the printing process has a predetermined back pressure, and h3 has a relationship of h3> h1 and h3 <β during the discharge processing. Is placed in.

Then, by periodically performing the ink ejection process, it is possible to prevent the occurrence of ejection defects due to the agglomerates. At this time, due to the above-mentioned head difference, the discharge process can be performed only by opening and closing the valve 371 provided in the discharge pipe 37, and the control can be simple. In addition, the ejection process can be performed without dripping ink from the nozzle N of the inkjet head 311 and without sucking outside air into the inkjet head 311. Therefore, after the ejection process, the printing process can be returned immediately by simply closing the valve 371, so that the printing process can be performed efficiently.

Further, since the discharge treatment can be performed only by the head difference, there is no need to prepare a drive source for another discharge or control the discharge, and the configuration can be simplified. Further, it is not necessary to consume the driving energy of the driving source, and the device can be a low-cost device and a low running cost device.

Further, since the on-off valve on the ink flow path is only on the discharge side and does not have to be on the supply side, the piping route and the on-off valve control can be simplified. In particular, on the supply side, when the ink pipe is also replaced for hygienic reasons, the on-off valve is not included, so the running cost does not increase as in the case where the on-off valve is disposable.

In addition, when reusing an on-off valve, it takes time to reliably clean the inside of a valve with a complicated shape, and it also takes time to inspect whether it has been properly cleaned, so the cost of reuse is high. , This running cost can also be deleted.

In addition, the risk of elution of impurities from the metal parts of the on-off valve can be eliminated.

In addition, in the case of tablets that are taken orally such as foods and drugs, germs should not propagate on the pipes. In this respect, not providing a valve can certainly eliminate the risk.

Since the ink is only discarded after the valve 371 on the discharge side, there is no problem even if the contamination remains.

In the above description, the height (head difference) from the nozzle forming surface 312 to the discharge side end surface of the discharge pipe 37 is set to h3. That is, in the first embodiment, the end face of the discharge pipe 37 on the discharge bottle BE side is set at a position higher than the liquid level in the discharge bottle BE. As described above, since the amount of ink used per day is known, the amount of ink discharged also corresponds to the amount of ink used. In addition, the amount of ink or cleaning liquid discharged by filling or cleaning the ink can also be set in advance. Therefore, the height of the liquid level in the finally reached discharge bottle BE can also be calculated. Therefore, the size and arrangement of the discharge pipe 37 and the discharge bottle BE may be set so that the end surface of the discharge pipe 37 on the discharge bottle BE side is located above the liquid level that finally reaches.

Further, the liquid level in the discharge bottle BE is not limited to such an arrangement, and even when the liquid level in the discharge bottle BE rises and the end surface of the discharge pipe 37 is below the liquid level, the liquid level in the discharge bottle BE is headed. It may be used as the standard of h3. That is, as shown in FIG. 2, when the end surface of the discharge pipe 37 is above the liquid level in the discharge bottle BE, the head difference h3 on the discharge side is from the nozzle forming surface 312 of the inkjet head 311 to the discharge pipe 37. It is the height to the end face on the discharge side, and when the end face of the discharge pipe 37 is below the liquid level in the discharge bottle BE as shown in FIG. 6, it is from the nozzle forming surface 312 of the inkjet head 311 to the inside of the discharge bottle BE. It is the height to the liquid level.

In any case, the head difference h3, the head difference h1, and β, which is the width of the head difference at which outside air is not drawn from the nozzle N, are h3> h1, h3 <β, and h1 <β as described above. It suffices if it is a relationship.

The total amount of drainage such as ink and cleaning liquid in the drainage bottle BE is detected by detecting the liquid level height of the drainage bottle BE, which is the limit of this relationship, with a sensor (not shown) or by detecting the weight of the drainage bottle BE. The liquid level height may be calculated from the above, and when the limit value at which the above relationship is broken is reached, a warning prompting the replacement of the discharge bottle BE or the discharge of the drainage from the discharge bottle BE may be issued.

Since h1 of the head difference on the supply side is a predetermined value that is generally fixed, the bottle is set so that the liquid level of the drainage liquid in the drain bottle BE is at a height located below h1 of the head difference and is the storage limit of the bottle. You may decide the arrangement and size of.

By doing so, it is not always necessary for the end face of the drainage pipe 37 to be located above the liquid level in the drainage bottle BE, the freedom of arrangement of the drainage pipe 37 and the drainage bottle BE is increased, and the tablet printing apparatus can be further operated. It can be made small, and the degree of freedom in the installation location of the tablet printing device is increased.

Further, in the first embodiment, it has been described that the valve 371 of the discharge pipe 37 is closed when the filling operation is completed. The end of this filling operation is, for example, by detecting the ink with the sensor KE provided in the discharge pipe 37 shown in FIG. At this time, the end face (liquid level) of the ink in the discharge pipe 37 is the end face on the discharge side of the discharge pipe 37, and it is desirable that the inside of the discharge pipe 37 is filled with ink. Alternatively, at least the sensor KE detects and closes the valve 371 so that the liquid level of the ink in the discharge pipe 37 at that time is below h1 of the head difference. By doing so, the reference for the water head difference h3 on the discharge side is the liquid level of the ink in the discharge pipe 37, but the water head difference h3 due to this liquid level becomes larger than h1. Therefore, when the valve 371 is opened at the discharge timing, h3> h1 and the ink is discharged from the discharge pipe 37 to the discharge bottle BE. Of course, the sensor KE may detect the ink on or below the discharge side end face of the discharge pipe 37. It can be reliably detected that the inside of the discharge pipe 37 is filled with ink.

(Other embodiments)
By the way, when the printing process is performed so as to coat the entire surface to be printed on the tablet surface, the amount of ink used is large, and as described above, the ink may be consumed before the aggregation of the composition portion of the ink progresses. In such a case, the time during which printing cannot be performed, that is, the time during which printing is stopped, is the time for ink to aggregate in the printing process due to the supply of tablets being stopped. Therefore, as the ejection interval time in the first embodiment, the printing stop time may be measured, and the ink may be ejected when the printing stop time reaches a predetermined time, that is, the ejection interval time. By doing so, it is possible to reduce the consumption of ink because the ink is not discharged in a state where the ink does not need to be discharged. In this case, in ST11 shown in FIG. 5, it is determined whether or not the print stop time has elapsed for a predetermined time.

As described above, the ejection interval time is determined based on the printing processing time or the printing stop time within the printing processing time, and the ejection timing is controlled based on the ejection interval time.

In the first embodiment, the on-off valve is not provided on the ink supply pipe 34, but if the material of the ink supply pipe 34 is flexible and it can be crushed from the outside to block the flow path, it is pinched. It is possible to open and close the flow path with a valve or the like. In this case, since the pinch valve is not replaced even when the ink supply pipe 34 is replaced, the running cost for discarding or cleaning the on-off valve does not increase.

Of course, the opening and closing of such a pinch valve may be controlled manually or based on an instruction from the control unit 5.

By providing the pinch valve on the ink supply pipe 34 in this way, for example, due to equipment trouble or maintenance, the ink bottle B can be temporarily removed or its height can be changed to h1 of the water head difference. However, even if a state deviates from the range defined in the first embodiment of the present invention, the pressure P in the inkjet head 311 can be set to a predetermined value by closing the pinch valve before the device trouble or maintenance process. Be maintained. Therefore, it is possible to prevent ink from dripping from the inkjet head 311 and outside air being sucked into the inkjet head 311 even during equipment troubles and maintenance.

Further, in the first embodiment described above, the moving device 36 that moves up and down by a drive source such as a motor has been described, but the present invention is not limited to this, and the height of the liquid level L of the ink in the ink bottle B can be adjusted. Any configuration may be used as long as it is used.

For example, the mounting table of the ink bottle B that moves up and down may be supported by an elastic body such as a spring.

As described above, the amount of ink consumed per unit time can be grasped by grasping the amount of ink used in advance. Therefore, when the height of the ink bottle itself is adjusted by using a spring manufactured with a spring constant set based on this consumption amount, the ink is supplied from the ink bottle B to the inkjet head 311. By maintaining h1 of the water head difference between the nozzle forming surface 312 of the set inkjet head 311 and the liquid level L of the ink in the ink bottle B at a predetermined value as constant as possible, the ink can be stably supplied. Can be done.

Further, instead of maintaining the head difference h1 by adjusting the height of the ink bottle B, a predetermined amount of ink set based on the amount of ink consumed in advance is supplied to the ink bottle. By doing so, h1 may be maintained. The moving device 36 that moves the ink bottle B up and down can be eliminated, and the cost of the device can be reduced.

Further, if the ink bottle B is made flexible, the height of the liquid level L of the ink inside the ink bottle itself can be adjusted by deforming the ink bottle itself. In this case, the ink bottle B can be deformed by a simple aperture mechanism or the like instead of a large-scale vertical movement mechanism.

Further, not only the vertical movement but also the ink bottle B itself may be rotated. With such rotation, the inclination of the bottle changes according to the consumption of ink, so that the operator can visually check the consumption state of ink more easily than operating the device. In the vertical movement of the ink bottle B accompanying the consumption of ink as described above, the movement is very slight, and it is difficult to visually grasp the amount of ink consumed depending on the shape of the bottle. By tilting the ink bottle B as in this modification, the arrangement of the bottles is magnified according to the amount of ink consumed, so that observation is easy. Moreover, since it is only rotated, it can be made into a simple mechanism instead of a large-scale vertical movement mechanism, it can be made more compact than the vertical movement, and the equipment cost is reduced. Furthermore, since it has a simple mechanism, the failure rate can be reduced.

Further, in the above-described first embodiment, the number of the inkjet heads 311 has been described as a single number, but a plurality of the inkjet heads 311 may be used. In this case, for example, an ink flow path as shown in FIG.

Even in this case, h1 of the head difference due to the pressure in each inkjet head 311 and the height of the liquid level L in the ink bottle B, and the end surface of the discharge pipe 37 from the nozzle forming surface 312 of each inkjet head 311 to the discharge bottle BE side. The relationship between h3, which is the head difference due to the height, and β, which is the width of the head difference where ink does not drip from the nozzle forming surface 312 and outside air is not drawn from the nozzle N, is the same as in the first embodiment.

Even if there are two inkjet heads 311 as shown in FIG. 7 and only one of them needs to be discharged, the valve of the discharge pipe 37 connected to the inkjet head 311 that needs to be discharged should be opened. Therefore, only the inkjet head 311 that requires the discharge treatment is discharged. That is, even if the ink supply pipe 34 is common to each of the inkjet heads 311 but does not flow from the ink supply path connected to the inkjet head 311 on the side where the valve is not opened. This is because the ink on the flow path cannot move to the side where the discharge treatment is performed because the valve is closed. At this time, since the pressure inside the inkjet head 311 that is not discharged is also within β of the head difference, no dripping or suction of outside air occurs.

Examples of tablets include bare tablets (bare tablets), sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-encapsulated tablets, multi-layer tablets, and nucleated tablets for pharmaceutical use and food and drink. In addition, various capsule tablets such as hard capsules and soft capsules can also be included in the tablets. These tablets will be described with the medicinal and eating habits in mind, but also include those used for washing, bathing, and fragrance.

When the tablet to be printed is for pharmaceutical use or food and drink, the ink used is preferably edible ink. Specifically, as edible pigments, amaranth, erythrosine, ponceau (above, red), tartrazine, sunset yellow FCF, β-carotene, crocin (above, yellow), brilliant blue FCF, indigo carmine (above, blue). ) And the like, and these are dispersed or dissolved in a vehicle, and if necessary, a dye dispersant (surfactant) is blended. Further, as the edible ink, any of synthetic dye ink, natural dye ink, dye ink, and pigment ink may be used.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Therefore, the described embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 1st transfer device 2 2nd transfer device 3 1st printing unit 4 2nd printing unit 5 Control unit 31, 41 Ink printing unit 311 Ink head 312 Nozzle forming surface 34 Supply pipe 36 Moving device 37 Discharge pipe 371 Valve L Liquid level B Ink bottle BE Discharge bottle S Tablet printing device C Transport device P Printing section K, KE sensor

Claims (4)

Conveyor and
An inkjet head that prints by ejecting ink from a nozzle on tablets transported by the transfer device.
An ink bottle containing ink supplied to the inkjet head via a supply tube connected to the inkjet head, and an ink bottle.
An discharge bottle provided separately from the ink bottle and accommodating ink discharged from the inkjet head via a discharge pipe connected to the inkjet head.
An on-off valve provided in the discharge pipe and
And at least the conveying device, the control unit controlling each part of the on-off valve provided in the ink jet head and the discharge pipe,
The control unit
A first state in which the end face of the supply pipe on the ink bottle side is arranged so as to be located in the ink contained in the ink bottle.
Emissions formed and the height of the nozzle forming surface of the nozzle of the ink-jet head is formed by a height of the liquid level of the ink in the height of the end face of the discharge bottle side of the ink discharge tube or discharge bottle water head difference of the side is, the the height of the liquid surface of the ink in the ink bottle, the height of the nozzle surface, the second that provided greater than the water head difference between the supply side, which is formed by the state,
Water head difference between the discharge side and the water head difference between the supply side, the so ambient air from the nozzle is less than the water head difference will be drawn, the height of the end face of the discharge bottle side of the ink of the discharge tube is Ru is set Third state,
With all the states of is maintained at the same time, discharge of the off valve in Rukoto be controlled to from the closed to the open, into the discharge bottle of the ink in the ink-jet head by using only the water head difference If, tablet printing apparatus characterized by performing the supply of the ink from the ink bottle into the ink jet head, simultaneously. The control unit
When the printing process is performed by the inkjet head, the on-off valve provided in the discharge pipe is closed, the time based on the printing process is measured by the inkjet head, and the time measured is a predetermined time. The tablet printing apparatus according to claim 1, wherein the on-off valve provided in the discharge pipe is sometimes opened. The tablet printing apparatus according to claim 1 or 2, wherein the supply pipe is not provided with an on-off valve. In a tablet printing method in which printing is performed on a conveyed tablet using an inkjet head that ejects ink from a nozzle.
To the inkjet headThrough the connected supply pipeThe ink from the ink bottle To the inkjet headWith the steps to supply
The step of printing with the inkjet head and
The step of timing the time based on the printing process and
When the timed time reaches a predetermined time, the printing process is stopped.The ink jet From ToheadThe ink, In a discharge bottle different from the ink bottleSteps to discharge and
The step of timing the time when the ink is discharged and
When the time for discharging the timed ink reaches a predetermined time, the step of stopping the discharge of the ink and restarting the printing process is provided.
In the step of ejecting the ink,
The end face of the supply pipe on the ink bottle side is housed in the ink bottle. The first state, which is located so that it is located in the ink,
Of the inkjet head,The head difference on the discharge side formed on the ink discharge side is provided to be larger than the head difference on the supply side formed on the ink supply side.Second state,
The head difference on the supply side and the head difference on the discharge side are provided so as to be smaller than the head difference in which outside air is sucked from the nozzle.Third state,
The on-off valve provided in the discharge pipe is opened from the closed state while all the states are maintained at the same time. By using only the head difference, the ink in the inkjet head is said to be in the ink. Discharge to the discharge bottle and the ink from the ink bottle to the inkjet head. Supply and at the same timeA tablet printing method characterized by that.

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