JP2023094845A - Tablet printer and tablet printing method - Google Patents

Abstract

To provide a tablet printer which can efficiently resolve a failure in the tablet printer while preventing reduction in the printing efficiency.SOLUTION: A tablet printer comprises: a conveyance unit which conveys a tablet; an ink jet head which performs printing on the tablet conveyed by the conveyance unit; a maintenance unit of the ink jet head; a movement unit which moves the ink jet head in the direction orthogonal to the conveyance direction of the tablet by the conveyance unit; an imaging unit which images the printed tablet; an image processing unit which processes the image captured by the imaging unit; and a calculation unit which calculates the non-defective ratio of the tablet on the basis of the image processed by the image processing unit. When the non-defective ratio calculated by the calculation unit is less than a prescribed value, the tablet printer executes maintenance of the ink jet head by the maintenance unit. When the frequency of the maintenance of the ink jet head by the maintenance unit is greater than a prescribed frequency, the tablet printer moves the ink jet head by the movement unit.SELECTED DRAWING: Figure 1

Description

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

2. Description of the Related Art In order to print identification information (an example of information) such as characters and marks on a tablet, a technique of printing using an inkjet head is known. A tablet printing apparatus using this technology conveys tablets by a conveying device such as a conveyor, and ejects ink from each nozzle of an inkjet head arranged above the conveying device toward the tablet passing below the inkjet head, Print identification information on tablets.

By the way, such a tablet printing apparatus may have problems such as failure to properly eject ink from the inkjet head, which may result in printing defective tablets.

When such a defective tablet occurs, it is necessary to stop the operation of the entire tablet printing apparatus, identify the cause, and remove the cause. As a result, printing efficiency decreases.

JP-A-7-081050

An object of the present invention is to provide a tablet printing apparatus that can efficiently eliminate defects in the tablet printing apparatus while preventing a decrease in printing efficiency.

A tablet printing apparatus according to an embodiment includes a conveying unit that conveys tablets, an inkjet head that prints on the tablet conveyed by the conveying unit, a maintenance unit of the inkjet head, and the inkjet head by the conveying unit. a moving unit that moves the tablet in a direction orthogonal to the conveying direction of the tablet; an imaging unit that images the tablet printed by the inkjet head; an image processing unit that processes the image captured by the imaging unit; a calculation unit that calculates a non-defective product rate of the tablets based on the image processed by the image processing unit, and when the non-defective product rate calculated by the calculation unit is below a predetermined value, the maintenance unit and performing maintenance of the inkjet head by the maintenance unit, and when the maintenance of the inkjet head by the maintenance unit exceeds a predetermined number of times, the inkjet head is moved by the moving unit to be used for printing on the tablet. It is characterized by changing the nozzle of the head.

A tablet printing method according to an embodiment includes a printing step of printing on a tablet to be conveyed with an inkjet head, an imaging step of imaging the tablet printed in the printing step, and the tablet based on the image captured in the imaging step. a maintenance step of performing maintenance on the inkjet head when the non-defective product ratio is below a predetermined value; and a moving step of moving the inkjet head in a direction orthogonal to the tablet conveying direction.

ADVANTAGE OF THE INVENTION According to embodiment of this invention, the tablet printing apparatus which can solve the defect of a tablet printing apparatus efficiently can be provided, preventing decline in printing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS The whole tablet printing apparatus side view which concerns on 1st embodiment of this invention. The top view of the conveyance part which concerns on 1st embodiment of this invention. FIG. 2 is a block diagram of a control section according to the first embodiment of the present invention; 4 is a flow chart of a printing process according to the first embodiment of the present invention; The whole tablet printing apparatus side view which concerns on 2nd embodiment of this invention.

<First embodiment>
A first embodiment will be described with reference to FIGS. 1 to 4. FIG.

(Configuration example of tablet printing device)
As shown in FIGS. 1 and 2, the tablet printing apparatus 1 according to the first embodiment includes a supply unit 10, a transport unit 20, a detection unit 30, a first imaging unit 40, and a printing unit 50. , a second imaging unit 60 , a collection unit 70 , a control device 80 , a maintenance unit 90 , and a cleaning unit 100 .

The supply section 10 has a hopper 11 , a chute 12 , an alignment feeder 13 and a transfer feeder 14 . The supply unit 10 is positioned on one end side of the transport unit 20 and is configured to be able to supply tablets T, which are objects to be printed, to the transport unit 20 . The hopper 11 accommodates a large number of tablets T and sequentially supplies the accommodated tablets T to the shooter 12 . The shooter 12 has a structure in which a vibration exciter is provided on the conveying path, conveys the tablets T supplied from the hopper 11 by vibration, and supplies them to the alignment feeder 13 . The alignment feeder 13 aligns the tablets T in a line and supplies them to the delivery feeder 14 . The transfer feeder 14 sequentially supplies the tablets T aligned in a line to the transport section 20 . The supply unit 10 is electrically connected to the control device 80 and its driving is controlled by the control device 80 .

The transport section 20 has a transport belt 21 , a drive pulley 22 , a plurality of driven pulleys 23 , a motor 24 , a position detector 25 and a suction chamber 26 . The conveying belt 21 is an endless belt, and is stretched over the drive pulley 22 and the driven pulleys 23 . The drive pulley 22 and the driven pulleys 23 are rotatably provided in an apparatus main body (not shown), and the drive pulley 22 is connected to a motor 24 . The motor 24 is electrically connected to the control device 80 and its driving is controlled by the control device 80 . The position detector 25 is a device such as an encoder and attached to the motor 24 . This position detector 25 is electrically connected to the control device 80 and transmits a detection signal to the control device 80 . The transport unit 20 rotates the transport belt 21 together with the driven pulleys 23 by rotating the driving pulley 22 by the motor 24, and transports the tablets T on the transport belt 21 in the rotation direction of the arrow H1 in FIG. 1, that is, the transport direction H1. do.

The conveyor belt 21 is formed with a plurality of circular suction holes 21a (see FIG. 2). These suction holes 21a are through holes for sucking tablets T, and are arranged in a line along the transport direction H1 so as to form a single transport path. Each suction hole 21a is connected to the inside of the suction chamber 26 via a suction path (not shown) formed in the suction chamber 26 (see FIG. 1), so that a suction force can be obtained by the suction chamber 26. It's becoming A pump is connected to the suction chamber 26 via a suction pipe (both not shown), and the pressure inside the suction chamber 26 is reduced by the operation of the pump. The suction pipe is connected to substantially the center of the side surface of the suction chamber 26 (the surface parallel to the conveying direction H1). In addition, the pump is electrically connected to the control device 80 and its drive is controlled by the control device 80 . When the suction chamber 26 is decompressed, the tablets T placed on the suction holes 21 a of the conveyor belt 21 are sucked by the suction holes 21 a and held on the conveyor belt 21 .

The detection unit 30 is positioned downstream in the transport direction H<b>1 from the position where the supply unit 10 is provided, and is provided above the transport belt 21 . The detection unit 30 detects the positions of the tablets T on the conveyor belt 21 in the X direction (see FIG. 2) by projecting and receiving laser light. As the detection unit 30, for example, a displacement sensor, a proximity sensor, or the like is used. As the displacement sensor, for example, various laser sensors such as a reflective laser sensor are used. The detection unit 30 is electrically connected to the control device 80 and transmits detection signals to the control device 80 .

The first imaging unit 40 is positioned downstream in the transport direction H<b>1 from the position where the detection unit 30 is provided, and is provided above the transport belt 21 . Based on the position information of the tablet T in the X direction detected by the detection unit 30, the first imaging unit 40 detects the position of the tablet T at the first imaging timing when the tablet T reaches the imaging position directly below the first imaging unit 40. An image is captured to acquire a first image including the upper surface of the tablet T, and the acquired first image is transmitted to the control device 80 . The first image is used to detect the positions of the tablet T in the X direction, Y direction and θ direction (see FIG. 2). As the first imaging unit 40, various cameras having imaging elements such as CCD (charge-coupled device) and CMOS (complementary metal oxide semiconductor) are used. The first imaging section 40 is electrically connected to the control device 80 and its drive is controlled by the control device 80 . In addition, illumination for imaging is also provided as needed.

Here, the positions of the tablet T in the X direction and the Y direction are, for example, the positions of the XY coordinate system with respect to the center (reference position) of the imaging area of the first imaging unit 40 . Further, the position in the θ direction is, for example, the position indicating the degree of rotation of the tablet T with respect to the center line in the Y direction of the imaging area of the first imaging unit 40 . The position in the θ direction is detected when the tablet T has a directional shape, such as when the tablet T is provided with a dividing line, or when the tablet T is molded in an elliptical, oval, or rectangular shape. be done.

The printing unit 50 has an inkjet head 51 . The inkjet head 51 is positioned downstream in the transport direction H<b>1 from the position where the first imaging unit 40 is provided, and is provided above the transport belt 21 . The inkjet head 51 has a plurality (for example, several hundred to several thousand) of nozzles 51a (see FIG. 2), and the direction in which the nozzles 51a are arranged in a row (nozzle row) is perpendicular to (intersects) the transport direction H1 in the horizontal plane. example). The inkjet head 51 is provided so as to be movable in the direction in which the nozzles 51a are arranged (the direction orthogonal to the transport direction H1) by the moving unit 52 . The inkjet head 51 ejects ink individually from each nozzle 51a by operating a driving element for each nozzle 51a. As the inkjet head 51, various inkjet print heads having drive elements such as piezoelectric elements, heating elements, or magnetostrictive elements are used. The inkjet head 51 and its moving portion 52 are electrically connected to the control device 80 and the driving thereof is controlled by the control device 80 .

The second imaging unit 60 is positioned downstream in the transport direction H1 from the position where the printing unit 50 is provided, and is provided above the transport belt 21 . Based on the X-direction position information of the tablet T detected by the detection unit 30, the second imaging unit 60 detects the position of the tablet T at the second imaging timing when the tablet T reaches the imaging position directly below the second imaging unit 60. An image is captured to acquire a second image including the upper surface of the tablet T, and the acquired second image is transmitted to the control device 80 . The second image is used to inspect the print pattern printed on the tablet T. FIG. As the second imaging section 60, various cameras having an imaging element such as a CCD or a CMOS, for example, are used as in the case of the first imaging section 40 described above. The second imaging section 60 is electrically connected to the control device 80 and its drive is controlled by the control device 80 . Illumination for imaging is also provided as needed.

The recovery unit 70 is positioned downstream in the transport direction H1 from the position where the second imaging unit 60 is provided, and is provided at the end portion of the transport unit 20 on the downstream side in the transport direction H1. The conveying unit 20 releases the holding of the tablet T when the tablet T on the conveying belt 21 reaches a predetermined position, for example, the downstream end of the conveying unit 20 in the conveying direction H1. The recovering unit 70 is configured to sort the tablets T that fall after being released from the holding by the conveying unit 20 into defective products and non-defective products and recover them. For example, by blowing air onto the falling tablets T and changing the falling direction of the tablets T depending on whether the tablets are defective or good, or by changing the falling path using a member such as a plate, the falling tablets T can be divided into defective and good. can be collected separately. For example, a bad product is a print-rejected tablet and a good product is a print-acceptable tablet. The collection unit 70 is electrically connected to the control device 80 and its driving is controlled by the control device 80 .

The control device 80 controls each unit of the tablet printing apparatus 1, such as the supply unit 10, the transport unit 20, the detection unit 30, the first imaging unit 40, the printing unit 50, and the second imaging unit, based on various information and various programs. 60, collection unit 70, maintenance unit 90, cleaning unit 100, and the like. The control device 80 also receives detection information (for example, a detection signal) transmitted from the position detector 25 and the detection unit 30, and also receives information transmitted from the first imaging unit 40 and the second imaging unit 60. Receive image information, etc. The control device 80 is implemented by, for example, an electronic circuit such as an integrated circuit or a computer.

The maintenance section 90 is for performing maintenance on the inkjet head 51 . The maintenance section 90 is provided at a position below the inkjet head 51 and not interfering with the nozzles 51a on the front side of the paper surface of FIG. The longitudinal direction of the maintenance section 90 is longer than the length in which the nozzles 51a of the inkjet head 51 are arranged. When maintenance of the inkjet head 51 is performed by the maintenance section 90, it is moved from the standby position to the maintenance position by a moving device (not shown). The maintenance section 90 is a well-known maintenance mechanism for an inkjet head having a drain pan, a wiper, and the like (not shown). Maintenance of the inkjet head 51 is performed by ejecting ink pressure-fed from an ink bottle (not shown) from the nozzle 51a toward the drain pan and wiping it off with a wiper.

The cleaning unit 100 is provided downstream of the collecting unit 70 in the transport direction H1 (below the suction chamber 26) and has a brush 102 rotatable about a rotating shaft 101. As shown in FIG. The rotating shaft 101 is provided so as to be movable between a standby position and a cleaning position by a moving mechanism (not shown). The standby position is a position where the brush 102 does not contact the conveyor belt 21 , and the cleaning position is a position where the brush 102 contacts the conveyor belt 21 . The rotating direction of the brush 102 is clockwise, which is the same as the rotating direction of the transport belt 21 (transport direction H1). The conveyor belt 21 moving below the suction chamber 26 moves from right to left on the plane of FIG. Therefore, although the rotating direction of the brush 102 rotates in the same direction as the conveying direction H1, the moving direction of the conveying belt 21 at the position in contact with the brush 102 faces the rotating direction of the brush 102 (see FIG. 1). (see arrow next to cleaning unit 100). A box that can store the powder removed from the surface of the conveying belt 21 may be provided below the brush 102 .

(Configuration example of control device)
Next, a configuration example of the control device 80 will be described with reference to FIG.

As shown in FIG. 3 , the control device 80 has an image processing section 81 , a storage section 82 , a control section 83 and a counter 84 . An input device 80 a and an output device 80 b are connected to the control device 80 . The input device 80a is implemented by, for example, a switch, touch panel, keyboard, mouse, or the like. Also, the output device 80b is implemented by, for example, a display, a lamp, a meter, or the like.

The image processing unit 81 takes in the first image captured by the first imaging unit 40 and the second image captured by the second imaging unit 60, and processes the images using a known image processing technique. . For example, the image processing section 81 processes the first image obtained from the first imaging section 40 and obtains the positions of the tablet T in the X direction, Y direction and θ direction. Further, the image processing unit 81 processes the second image obtained from the second imaging unit 60, and obtains the printing position, shape, and size of the printing pattern (for example, characters and marks) printed on the tablet T. do. The image processing unit 81 transmits to the control unit 83 the obtained positional information of each tablet T in the X direction, the Y direction, and the θ direction, as well as the printing position information, the shape information, and the size information of the printing pattern on each tablet T. .

The storage unit 82 stores processing information, various programs, and the like. For example, it is realized by a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 82 stores print data related to printing, moving speed data of the conveying belt 21, and the like. The print data includes print pattern information such as characters and marks.

The control unit 83 is, for example, a computer such as a CPU (Central Processing Unit) or MCU (Micro Controller Unit), and controls each unit. For example, the control unit 83 controls the supply unit 10, the transport unit 20, the detection unit 30, the first imaging unit 40, the printing unit 50, the second imaging unit, based on various information and various programs stored in the storage unit . It controls the unit 60, the collection unit 70, the image processing unit 81, the storage unit 82, the maintenance unit 90, the cleaning unit 100, and the like. The control unit 83 also receives detection signals and the like transmitted from the detection unit 30 and the position detector 25 .

For example, the control unit 83 acquires the position of the tablet T in the X direction on the transport belt 21 based on the detection information transmitted from the detection unit 30, that is, the timing at which the tablet T on the transport belt 21 is detected, and detects the position of the tablet T on the transport belt 21. Based on the position information indicating the position of T in the X direction, the first imaging timing of the first imaging unit 40, the printing start timing of the inkjet head 51 of the printing unit 50, and the second imaging timing of the second imaging unit 60. are set, and timing information indicating these timings is generated and stored in the storage unit 82 . The print start timing is the timing to start printing on the tablet T that has reached the printing position directly below the inkjet head 51 . Note that the control unit 83 can acquire information such as the movement amount (rotation amount) and speed of the conveying belt 21 based on the detection information transmitted from the position detector 25 .

Further, based on the positional information of the tablet T in the X direction, Y direction and θ direction transmitted from the image processing part 81, the control part 83 sets the printing conditions for the tablet T having the positional information. For example, the control unit 83 determines the range of the nozzles 51a to be used for printing the target tablet T in the inkjet head 51, i.e., the range of nozzles to be used, based on the positional information of the tablet T in the Y direction and the print data. Set printing conditions including nozzle range and print start timing. When the tablet T has a directionality, the control unit 83 sets the printing conditions based on the positional information of the tablet T in the θ direction, in correspondence with the position of the tablet T in the θ direction. As an example, the control unit 83 registers in the storage unit 82 180 print patterns obtained by rotating the orientation of the print pattern by 1 degree in a range of 0 to 179 degrees, and selects one of these print patterns. A printing pattern with an angle that matches the position of the tablet T in the θ direction is selected to set printing conditions.

In addition, based on the print position information, shape information, and size information of the print pattern printed on the tablet T, which are transmitted from the image processing unit 81, the control unit 83 allows the print pattern to be printed on the tablet T in a predetermined shape and size. It is determined whether or not the printed pattern has been printed at a predetermined position, that is, whether or not the printed pattern has been normally printed on the tablet T (printing state inspection). For example, in determining the shape and size of the printed pattern, the control unit 83 registers a printed pattern for inspection in the storage unit 82, and stores the printed pattern for inspection and the actual printed pattern on the tablet T after printing ( The printed pattern printed on the tablet T). As a result of the comparison, the "defective" tablets T are counted by a counter 84, which will be described later. It is determined whether or not the non-defective product rate is below a predetermined non-defective product rate (for example, 99%) (the controller functions as a calculator). Furthermore, the control unit 83 controls maintenance timing of the inkjet head 51 by the maintenance unit 90 , cleaning timing by the cleaning unit 100 , and movement timing of the inkjet head 51 , which will be described later.

Note that the control unit 83 stores various types of information (for example, position information, timing information, printing conditions, printing quality information, etc.) in the storage unit 82 as appropriate. For example, the various information is deleted from the storage unit 82 when a predetermined time (for example, several seconds) has passed after dropping from the downstream end of the transport unit 20 in the transport direction H1. However, if such information is required in a post-process or the like, it is also possible to leave various information for each tablet T without erasing it.

The counter 84 counts the total number of tablets T (the number of tablets detected by the detection unit 30) and the above-described defective tablets. Also, the number of times of maintenance is counted by the maintenance section 90, which will be described later.

(Printing process)
Next, the printing process performed by the above tablet printing apparatus 1 will be described with reference to FIGS. 1 to 3. FIG. The printing process also includes an inspection process. Various types of information such as data required for printing are stored in the storage unit 82 in advance.

When the tablet printing apparatus 1 starts printing, the motor 24 is driven, and the transport belt 21 rotates in the transport direction H1 as the drive pulley 22 and the driven pulley 23 are rotated by the motor 24 . While the transport belt 21 is rotating in the transport direction H1, the tablets T are sequentially supplied from the hopper 11 to the shooter 12 and then supplied from the shooter 12 to the alignment feeder 13 . The tablets T are arranged in a line by an alignment feeder 13 and fed via a delivery feeder 14 onto a conveying belt 21 at random rather than at regular intervals. The tablets T supplied onto the transport belt 21 are arranged in a line on the transport belt 21 and transported at a predetermined moving speed.

The tablets T on the conveyor belt 21 are detected by the detector 30 . Specifically, the tablet T on the conveying belt 21 is detected by the detection unit 30 at the timing when it reaches the detection position (for example, the irradiation position of the laser beam) immediately below the detection unit 30, and the tablet T is detected based on the timing at which the tablet T is detected. , the position of the tablet T in the X direction on the transport belt 21 is recognized by the control unit 83 . Position information indicating the position of the tablet T in the X direction is generated by the control unit 83 and stored in the storage unit 82 .

Next, the tablet T on the conveying belt 21 is imaged by the first imaging section 40 . Specifically, the tablet T on the conveying belt 21 is imaged by the first imaging unit 40 at the first imaging timing when it reaches the imaging position directly below the first imaging unit 40 , and the first imaging unit 40 A first image obtained by imaging is transmitted to the control device 80 . Based on this first image, positional information of the tablet T in the X direction, the Y direction, and the θ direction is generated by the image processing unit 81 and stored in the storage unit 82 . Based on the positional information of the tablet T in the X direction, Y direction and θ direction and the information such as the printing pattern, the printing conditions including the usable nozzle range and the printing start timing are set in the storage unit 82 . The ejection timing for the tablet T (timing for ejecting ink on the tablet T) is determined based on the print start timing (timing for starting printing on the tablet T).

Printing is executed by the printing unit 50 based on the printing conditions. That is, the control unit 83 controls the inkjet head 51 of the printing unit 50 to print a predetermined print pattern on the tablets T on the conveying belt 21 . More specifically, the tablets T on the transport belt 21 that have passed under the first imaging unit 40 are printed by the inkjet head 51 based on the above-described printing conditions at the printing start timing when they reach the printing position directly below the inkjet head 51. printed. In the inkjet head 51, ink is appropriately ejected from each nozzle 51a, and a print pattern (eg, number, alphabet, katakana, symbol, figure) is printed on the surface to be printed which is the upper surface of the tablet T. The ink applied to the tablet T dries naturally during transportation. A drying section (not shown) that performs drying by gas or heat may be provided to compensate for the drying of the ink.

After that, the printed tablet T on the conveying belt 21 is imaged by the second imaging unit 60 . Specifically, the printed tablet T on the conveyor belt 21 is imaged by the second imaging unit 60 at the second imaging timing when it reaches the imaging position directly below the second imaging unit 60, and the second imaging is performed. A second image obtained by imaging by the unit 60 is transmitted to the control device 80 .

This second image is processed by the image processing section 81 of the control device 80 . Specifically, the image processing unit 81 acquires information about the printed pattern printed on the tablet T, that is, the print position, shape, and size of the printed pattern. The second image transmitted from the second imaging unit 60 is processed by the image processing unit 81 to generate inspection information indicating the printing position, shape, and size of the print pattern already printed on the tablet T, and stored in the storage unit 82. Saved.

Based on this inspection information, the control unit 83 executes the print condition inspection. Specifically, the control unit 83 determines whether or not the print pattern is normally printed on the tablet T based on the inspection information related to the printing position, shape, and size stored in the storage unit 82, and the tablet T is printed. Print quality information indicating quality is generated and stored in the storage unit 82 . For example, in the print state inspection, the print pattern used for printing is stored in the storage unit 82 as the print pattern for inspection, and the non-defective product information about the predetermined print position, shape, and size of the print pattern for inspection and The stored inspection information about the print position, shape, and size of the actual printed print pattern is compared to determine whether the print pattern was normally printed on the tablet T (pass or fail).

Finally, the tablets T on the conveying belt 21 are recovered by the recovering section 70 . Specifically, when the tablet T after inspection is positioned at the downstream end of the conveyor belt 21 as the conveyor belt 21 moves, it is released from the state held by the conveyor belt 21 and dropped from the conveyor belt 21 to be collected. Collected by unit 70 . At this time, the acceptable non-defective tablets T drop as they are and are collected by the recovery unit 70, while the non-defective non-defective tablets T are separated from the non-defective tablets by air blowing while they are dropping from the conveying belt 21. is collected by the collecting unit 70.

(Maintenance process and inkjet head movement process)
Next, a maintenance process for the inkjet head 51 and the transport section 20 (transport belt 21) and a moving process for the inkjet head 51 will be described with reference to FIG. In order to understand the maintenance process and the inkjet head moving process, a part of the above-described printing process will be described.

As described above, when the printing process is started, the inkjet head 51 prints on the tablets supplied onto the conveying belt 21 (S1). The printed tablet T is imaged by the second imaging unit 60 (S2). Based on the image captured by the second imaging unit 60, the control unit 83 determines whether the printing on the tablet T is good or defective (S3), calculates the good product rate, and determines whether the product is defective. If there is, this is reflected in the non-defective product rate (S4). The control unit 83 determines whether the non-defective product rate is below a predetermined value (for example, 99%) (S5). is carried out (S6). At the same time, the cleaning unit 100 also cleans the conveying unit 20 (conveying belt 21) (S6). At this time, the vibration exciter (not shown) of the shooter 12 is turned off to stop the vibration, and the rotation direction of the alignment feeder 13 is switched from A1 to the opposite direction (A2) for a predetermined time (for example, 10 seconds). As a result, the tablets T supplied to the first feeder 13 are reversed without being supplied to the second feeder 14 , and the reversed tablets T are temporarily collected in the box 130 . After that, the rotation of the alignment feeder 13 is stopped. In this way, new tablets T are prevented from being supplied to the conveyor belt 21 . At this time, the tablets T placed on the conveying belt 21 are conveyed to the collecting section 70 and collected without being printed. When the maintenance of the inkjet head 51 by the maintenance unit 90 and the cleaning of the conveying belt 21 by the cleaning unit 100 are completed, the control unit 83 determines whether or not the maintenance and cleaning have exceeded a predetermined number of times (for example, three times) (S7 ), when the maintenance and cleaning is for the first time (N of S7), the vibration exciter of the shooter 12 is turned on, the rotation of the alignment feeder 13 is restarted, and the tablets T are supplied to the conveyor belt 21. , resumes the printing process. When the number of times of maintenance by the maintenance section 90 is, for example, the fourth (Y in S7), after the fourth maintenance by the maintenance section 90 is completed, the ink jet head 51 is moved in a predetermined direction by a predetermined distance, thereby expanding the usable nozzle range. (S8). When the movement of the inkjet head 51 is completed, the supply of the tablets T is resumed and the printing on the tablets T is resumed (S9). When the maintenance process and the ink jet head moving process are completed in this way, and printing on the planned number of tablets T is completed (Y in S10), the printing process is completed. Note that the tablets T temporarily stored in the box 130 may be put into the hopper 11 again after that.

Here, the cleaning of the conveying unit 20 (conveying belt 21) by the cleaning unit 100 is performed by moving the brush 102 to the cleaning position where it contacts the conveying belt 21, as described above. The brush 102 of the cleaning unit 100 scrapes off the tablet powder adhering to the conveying belt 21 by rubbing itself against the conveying belt 21 . The tablet powder adhering to the conveying belt 21 falls due to gravity to some extent, but the tablet powder remains adhered to the conveying belt 21 and accumulates due to the charging of the conveying belt 21, and the tablets placed thereon sway and stabilize. It may not be sucked and held. In this way, if printing is performed by the inkjet head 51 in a state in which the tablet is not stably sucked and held, characters printed on the tablet may be misaligned even though there is no problem with the inkjet head 51 . , may bleed.

Further, maintenance of the inkjet head 51 by the maintenance section 90 is performed by moving the maintenance section 90 to a position (maintenance position) immediately below the nozzles 51a of the inkjet head 51, as described above. When the ink near the nozzles dries, some or all of the nozzles in the inkjet head become blocked, causing the nozzles to not eject ink, the ejection direction to bend, or the amount of ink ejected to decrease. It is known that ejection failure such as decrease of Such an ejection failure is often resolved by maintenance by the maintenance unit 90 (the above-described pressure-feeding of ink and wiping with a wiper). However, if a particular nozzle 51a has already reached the end of its service life due to a large number of uses, or if the nozzle 51a is clogged with ink to the extent that it cannot be resolved by maintenance, it is rare that the ejection failure will not be resolved even if maintenance is performed. be. In addition, the inkjet head 51 requires high accuracy in positioning. If the position of the inkjet head 51 deviates from the predetermined position, the printing position deviation on the tablet T will occur. Therefore, it is desirable to minimize the number of movements of the inkjet head.

Therefore, as in the present embodiment, maintenance of the inkjet head 51 by the maintenance unit 90 and cleaning of the conveying belt 21 by the cleaning unit 100 are performed a predetermined number of times, which is the main cause of printing defects. Maintenance for removing the clogging of the nozzles 51a of the inkjet head 51 and cleaning of the conveying belt 21 are performed. This eliminates the cause of poor printing in most cases. If the non-defective product rate is less than the predetermined value of 99% even though the maintenance by the maintenance unit 90 and the cleaning by the cleaning unit 100 are continuously performed more than three times, which is the predetermined number of times, the nozzles of the inkjet head 51 Considering the possibility that the nozzle 51a has reached the end of its life, the inkjet head 51 is moved by the moving unit 52 to change the nozzle 51a to be used for printing.

Here, the moving distance of the inkjet head 51 is, for example, a position where the usable nozzle range before movement and the usable nozzle range after movement do not overlap (the nozzle 51a used before movement does not face the tablet T). position). Alternatively, if it is known in which area of the inkjet head 51 the nozzles 51a are causing the ejection failure, the moving distance of the inkjet head 51 may be determined so as to avoid using this area. Further, the moving direction may be the depth direction of the paper surface of FIG. 1 or the front direction.

In order to count the number of times maintenance is performed by the maintenance section 90, a time limit may be set. For example, if the time required for the non-defective product rate to fall below a predetermined value after performing maintenance exceeds a predetermined time (for example, 60 minutes), the It is possible that the cause of the defect and the cause of the next defect that occurred when the non-defective product rate fell below a predetermined value were different. returns the count of counter 84 to zero.

When the tablet T is put into the apparatus and printing is started, or when printing is resumed after maintenance by the maintenance section 90 and cleaning by the cleaning section 100 are finished, it takes about 3 minutes, for example, to calculate the non-defective product rate. is set so that the non-defective product rate is not calculated during this period. This is in order to accurately calculate the non-defective product rate by waiting until the amount of printed tablets, which is the parameter for calculating the non-defective product rate, increases sufficiently. Alternatively, even if the non-defective product rate falls below a predetermined value during this period, the maintenance operation may not be performed.

As described above, according to the first embodiment, it is possible to minimize the number of times the inkjet head is moved, and to efficiently print tablets while preventing a decrease in printing efficiency without stopping the entire apparatus. It is possible to solve the problem of the printing device.

<Other embodiments>
In the above-described embodiment, the non-defective product rate of the tablets T is exemplified based on the presence or absence of printing defects, but is not limited to this. may be calculated.

In the above-described embodiment, maintenance of the inkjet head 51 by the maintenance unit 90 and cleaning of the conveying unit 20 by the cleaning unit 100 are performed when the non-defective product rate falls below a predetermined value. The maintenance is not limited to this, and only the maintenance by the maintenance section 90, which has the highest probability of leading to the resolution of the defect, may be performed.

In the above-described embodiment, when the non-defective product rate falls below a predetermined value, the vibration of the chute 12 is stopped and the rotation direction of the aligning feeder 13 is reversed for a predetermined period of time and then stopped. is not supplied onto the conveying belt 21, but the present invention is not limited to this. For example, a shutter may be provided at the outlet of the shooter 12 so that the supply of the tablets T is stopped by closing the shutter when the ratio of non-defective products falls below a predetermined value. Alternatively, the feeding of the tablets T to the conveyor belt 21 is stopped by turning off the suction of the delivery feeder 14 at the position where the tablets T are received from the alignment feeder 13 without changing the rotation direction of the alignment feeder 13. Also good. At this time, the tablets on the alignment feeder 13 may be collected by setting a box 130 below the alignment feeder 13 (on the right side of the alignment feeder 13 in FIG. 1).

In the above-described embodiment, the cleaning section 100 is provided below the suction chamber 26, but this is not the only option. For example, it may be provided between a plurality of driven pulleys 23 . It may be provided anywhere as long as it is possible to clean the conveying belt 21, but the location where the tablets T are not placed (the position where the tablets T are supplied from the transfer feeder 14 to the conveying belt 21 is discharged to the recovery unit 70). By providing it at a location away from the transport path of the tablet T up to the position where the tablet T is transported, it is possible to prevent the transport of the tablet T from being hindered. Moreover, although the cleaning part 100 has illustrated having the rotatable brush 102, it is not restricted to this. For example, it may be a nozzle that sucks foreign matter such as tablet powder present on the conveying belt 21, or a nozzle that blows off the foreign matter on the conveying belt 21 by blowing gas. Alternatively, it may be an elastic wiper for sweeping out foreign matter on the conveying belt 21 . Furthermore, it may be a wiping cloth or a non-woven fabric moistened by impregnating it with a volatile liquid. Also, a plurality of these may be provided in combination.

Although the shape of the conveying belt 21 was not specified in the above-described embodiment, a conveying belt having a pattern three-dimensionally formed on the surface thereof may be used. The tablet printing apparatus 1 may be provided with a 3D inspection unit (not shown) for inspecting the appearance of the tablet T, but if the conveying belt 21 has a pattern shape on the surface, this A 3D inspection unit may be used to check the transport belt for damage.

Further, in the above description, the tablet T is conveyed in a single row, but this is not a limitation, and the number of rows may be two or more, and is not particularly limited. However, the number of conveying belts 21a may be two or more, and is not particularly limited. Also, the number of inkjet heads 24 and 54 may be two or more, and is not particularly limited.

In the above description, the inkjet head 51 is a print head in which the nozzles 51a are arranged in a line, but the present invention is not limited to this. good. Alternatively, a plurality of inkjet heads 51 may be arranged in a horizontal plane in a direction orthogonal to the transport direction H1.

Further, in the above description, the tablets T are supplied onto the conveying belt 21 at random rather than at regular intervals, but the invention is not limited to this, and may be supplied at regular intervals. Further, in the above description, the tablets T are sucked and held by the suction holes formed on the conveying belt 21, but the present invention is not limited to this. Alternatively, it may be held and conveyed on the conveyor belt 21 by its own weight.

Further, in the above description, printing on one side of the tablet T is exemplified, but the present invention is not limited to this. 2 imaging units 60 are combined into one unit, and the units are stacked vertically, and the tablet T printed by the upper transport unit 20 is reversed and delivered to the lower transport unit 20, and both sides of the tablet T are transferred. It may be printed.

Here, the above-mentioned tablet T can include tablets used for medicine, eating and drinking, cleaning, industrial use, or fragrance use. Tablets T include uncoated tablets (uncoated tablets), sugar-coated tablets, film-coated tablets, enteric-coated tablets, gelatin-coated tablets, multi-layer tablets, dry-coated tablets, etc. Various capsules such as hard capsules and soft capsules are also available. can be included in tablet T. Furthermore, the shape of the tablet T includes various shapes such as a disk shape, a lens shape, a triangular shape, and an elliptical shape. Moreover, when the tablet T to be printed is for medical use or food and beverage use, edible ink is suitable as the ink to be used. As the edible ink, synthetic pigment ink, natural pigment ink, dye ink, or pigment ink may be used.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

1 tablet printing device 20 conveying unit 30 detecting unit 40 first imaging unit 50 printing unit 51 inkjet head 51a nozzle 52 moving unit 60 second imaging unit 80 control device 81 image processing unit 83 control unit (calculation unit)
90 maintenance section 100 cleaning section

ADVANTAGE OF THE INVENTION According to embodiment of this invention, the tablet printing apparatus and tablet printing method which can perform defect resolution of a tablet printing apparatus efficiently can be provided, preventing decline in printing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS The whole tablet printing apparatus side view which concerns on 1st embodiment of this invention. The top view of the conveyance part which concerns on 1st embodiment of this invention. FIG. 2 is a block diagram of a control section according to the first embodiment of the present invention; 4 is a flow chart of a printing process according to the first embodiment of the present invention ;

Further, based on the positional information of the tablet T in the X direction, Y direction and θ direction transmitted from the image processing part 81, the control part 83 sets the printing conditions for the tablet T having the positional information. For example, the control unit 83 determines the range of the nozzles 51a to be used for printing the target tablet T in the inkjet head 51, i.e., the range of nozzles to be used, based on the positional information of the tablet T in the Y direction and the print data. Set printing conditions including nozzle range and print start timing. When the tablet T has a directional shape , the control unit 83 sets the printing conditions based on the positional information of the tablet T in the θ direction, in correspondence with the position of the tablet T in the θ direction. As an example, the control unit 83 registers in the storage unit 82 180 print patterns obtained by rotating the orientation of the print pattern by 1 degree in a range of 0 to 179 degrees, and selects one of these print patterns. A printing pattern with an angle that matches the position of the tablet T in the θ direction is selected to set printing conditions.

Finally, the tablets T on the conveying belt 21 are recovered by the recovering section 70 . Specifically, when the tablet T after inspection is positioned at the downstream end of the conveyor belt 21 as the conveyor belt 21 moves, it is released from the state held by the conveyor belt 21 and dropped from the conveyor belt 21 to be collected. Collected by unit 70 . At this time, the acceptable good tablets T drop as they are and are collected by the recovery unit 70, but the unacceptable defective tablets T are classified as non-defective tablets by being blown with air while they are falling from the conveying belt 21. It is divided and collected by the collecting unit 70 .

As described above, when the printing process is started, the inkjet head 51 prints on the tablets supplied onto the conveying belt 21 (S1). The printed tablet T is imaged by the second imaging unit 60 (S2). Based on the image captured by the second imaging unit 60, the control unit 83 determines whether the printing on the tablet T is good or defective (S3), calculates the good product rate, and determines whether the product is defective. If there is, this is reflected in the non-defective product rate (S4). The control unit 83 determines whether the non-defective product rate is below a predetermined value (for example, 99%) (S5). is carried out (S6). At the same time, the cleaning unit 100 also cleans the conveying unit 20 (conveying belt 21) (S6). At this time, the vibration exciter (not shown) of the shooter 12 is turned off to stop the vibration, and the rotation direction of the alignment feeder 13 is switched from A1 to the opposite direction (A2) for a predetermined time (for example, 10 seconds). As a result, the tablets T supplied to the alignment feeder 13 flow backward without being supplied to the transfer feeder 14 , and the tablets T flowing backward are temporarily collected in the box 130 . After that, the rotation of the alignment feeder 13 is stopped. In this way, new tablets T are prevented from being supplied to the conveyor belt 21 . At this time, the tablets T placed on the conveying belt 21 are conveyed to the collecting section 70 and collected without being printed. When the maintenance of the inkjet head 51 by the maintenance unit 90 and the cleaning of the conveying belt 21 by the cleaning unit 100 are finished, the control unit 83 determines whether or not the number of times of maintenance and cleaning has exceeded a predetermined number of times (for example, three times) (S7 ), when the maintenance and cleaning is for the first time (N of S7), the vibrator of the shooter 12 is turned on, the rotation of the alignment feeder 13 is restarted, and the tablets T are supplied to the conveyor belt 21. , resumes the printing process. When the number of times of maintenance by the maintenance section 90 is, for example, the fourth (Y in S7), after the fourth maintenance by the maintenance section 90 is completed, the ink jet head 51 is moved in a predetermined direction by a predetermined distance, thereby expanding the usable nozzle range. (S8). When the movement of the inkjet head 51 is completed, the supply of the tablets T is restarted and the printing on the tablets T is restarted (S9). When the maintenance process and the ink jet head moving process are completed in this way, and printing on the planned number of tablets T is completed (Y in S10), the printing process is completed. Note that the tablets T temporarily stored in the box 130 may be put into the hopper 11 again after that.

Here, the movement distance of the inkjet head 51 is, for example, a position where the range of nozzles used before movement and the range of nozzles used after movement do not overlap ( a position where the nozzles 51a used before movement do not face the tablet T). Determined to be Alternatively, if it is known in which area of the inkjet head 51 the nozzles 51a are causing the ejection failure, the moving distance of the inkjet head 51 may be determined so as to avoid using this area. Further, the moving direction may be the depth direction of the paper surface of FIG. 1 or the front direction.

<Other embodiments>
In the above-described embodiment, the non-defective rate of tablets T is calculated based on the presence or absence of printing defects, but the present invention is not limited to this. A non-defective product rate may be calculated.

Further, in the above description, the tablet T is conveyed in a single row, but this is not a limitation, and the number of rows may be two or more, and is not particularly limited. However, the number of conveyor belts 21 may be two or more, and is not particularly limited. Also, the number of inkjet heads 51 may be two or more, and is not particularly limited.

Claims (4)

a conveying unit that conveys tablets;
An inkjet head that prints on the tablet transported by the transport unit;
a maintenance section for the inkjet head;
a moving unit that moves the inkjet head in a direction perpendicular to the direction in which the tablet is conveyed by the conveying unit;
an imaging unit that captures an image of the tablet printed by the inkjet head;
an image processing unit that processes an image captured by the imaging unit;
a calculation unit that calculates a non-defective product rate of the tablet based on the image processed by the image processing unit;
has
performing maintenance of the inkjet head by the maintenance unit when the non-defective product rate calculated by the calculation unit is below a predetermined value;
When maintenance of the inkjet head by the maintenance unit exceeds a predetermined number of times, the inkjet head is moved by the moving unit to change nozzles of the inkjet head used for printing on the tablet. tablet printing equipment. further comprising a cleaning unit that cleans the conveying unit;
The tablet printing apparatus according to claim 1, wherein the cleaning section cleans the conveying section at a timing when the maintenance section performs maintenance of the inkjet head. The tablet printing apparatus according to claim 1 or 2, wherein the calculation unit calculates a non-defective product rate including appearance defects of the tablet based on the image. A printing process that prints on the transported tablet with an inkjet head,
An imaging step of imaging the tablet printed in the printing step;
a calculation step of calculating a non-defective product rate of the tablet based on the image captured in the imaging step;
a maintenance step of performing maintenance on the inkjet head when the non-defective product rate falls below a predetermined value;
a moving step of moving the inkjet head in a direction perpendicular to the conveying direction of the tablet when the number of times of maintenance of the inkjet head exceeds a predetermined number;
A tablet printing method comprising:

Images