JPH10278376A - Printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable direct printing to various kinds of print media, by holding rotatably a print medium having a print face of a predetermined radius of curvature, and making a gap of a print head to the print medium adjustable by a gap adjustment plate. SOLUTION: In printing to an outer circumferential face 26 of a cylindrical body 19 as a print medium, the cylindrical body 19 is held by holding jaws 17, 17, and the holding jaw 17 is rotated by a driving motor 24 so that a center of curvature of a print face becomes a rotation center. At this time, a gap between a bracket 30 holding an ink-jet head 25 slidably and the print face is detected by a gap sensor 27. On the basis of the detection result, an adjustment plate-driving motor 36 is controlled to be driven so as to make constant the gap between the print face and ink-jet head 25. A gap adjustment plate 33 is rotated by a driving power of the motor, and a head holder 29 is moved back or forward in a radial direction along a scroll groove 34 formed in the adjustment plate 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus for printing on a printing medium having a printing surface with a predetermined radius of curvature, such as a cylindrical object.

[0002]

2. Description of the Related Art Quality assurance of design patterns such as pictures and patterns on the outer peripheral surface of cylindrical objects such as cans and tea caddies, or explanations and precautions of product names and usage methods, and display of producer names, etc. As a method of printing items, the above-mentioned notation is performed on paper or film by screen printing or offset printing, and the printed paper or film is wound around the outer peripheral surface of the cylindrical object and adhered,
Alternatively, the above-mentioned notation is generally printed on the outer peripheral surface of a cylindrical object by screen printing.

[0003]

In a conventional method in which a printed matter such as paper or film is attached to the outer peripheral surface of a cylindrical object, or is directly printed on the outer peripheral surface of the cylindrical object by screen printing, a conventional method is used. The contents change,
Each time the dimensions of the cylindrical object are changed, it is necessary to newly make a printing plate, and the date and time required for manufacturing the printing plate are required. For this reason, not only the notation cannot be quickly changed, but also the production cost of the printing plate increases.

[0004] Such a problem is remarkable especially in the case of a product manufactured in a small lot because it takes time to set a printing plate on a printing press. In addition, if the contents of the notation differ from one another, such as the serial number of the product, the date and time of manufacture, and the like every day, a special printing machine for that purpose must be additionally provided, which has the disadvantage of increasing the equipment cost.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing method capable of directly printing on various types of printing media each having a printing surface with a predetermined radius of curvature, irrespective of screen printing or the like requiring a printing plate. It is to provide a device.

[0006]

SUMMARY OF THE INVENTION A printing apparatus according to the present invention is a printing apparatus for performing printing using a print head on a print medium having a print surface having a predetermined radius of curvature, and a medium holding means for holding the print medium. Medium rotation means for driving and rotating the medium gripping means at a predetermined speed such that the center of curvature of the print surface becomes the rotation center; and sliding the print head in a direction opposite to the rotation center of the medium rotation means. A bracket that is freely held, a gap sensor that is slidably held in the bracket in a direction opposite to a rotation center of the medium rotating unit, and that detects a distance between the print head and the printing surface; A gap adjustment plate having a rotation center coaxial with the rotation center of the rotating means, and an adjustment plate driving hand for driving and rotating the gap adjustment plate Connecting the gap adjustment plate with the gap sensor and the print head, and rotating the gap adjustment plate in a linear movement of the gap sensor and the print head in a direction facing a rotation center of the medium rotating unit. A power transmission mechanism for converting, and control means for controlling the adjustment plate driving means based on a detection signal from the gap sensor so that a distance between the print surface and the print head is constant. It is a feature.

According to the present invention, the print medium is gripped by the medium gripping means, and the print medium is driven and rotated at a predetermined speed by the medium rotating means around the center of curvature of the print surface of the print medium as the center of rotation.

On the other hand, when the adjusting plate driving means is operated, the gap adjusting plate rotates to move the gap sensor and the print head attached to the bracket in the direction opposite to the rotation center of the medium rotating means, so that the print medium is printed. The spacing between the print surface and the gap sensor and printhead changes.

Here, the gap sensor attached to the bracket detects the distance between the print head and the print surface of the print medium and outputs this to the control means. The control unit controls the operation of the adjusting plate driving unit based on the detection signal from the gap sensor so that the interval between the print medium and the print head becomes a predetermined interval.

As a result, printing is performed in a state where the distance between the print head and the print surface of the print medium is always constant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a printing apparatus according to the present invention, a power transmission mechanism is provided with a plurality of scroll grooves formed in a gap adjusting plate, a gap sensor and a print head, and respectively engages with these scroll grooves. In this case, the engagement pin engages with a slide guide groove formed on the bracket to guide the slide of the gap sensor and the print head with respect to the bracket. Is preferred.

Further, the print medium may be a cylindrical body. In this case, the medium gripping means preferably has a plurality of gripping jaws abutting on the inner peripheral surface of the cylindrical body.

On the other hand, the print head may be an ink jet head formed so that an ejection port for ejecting ink faces a print surface of a print medium. In this case, the bracket ejects inks of different hues respectively. A plurality of inkjet heads may be radially supported. Further, the ejection ports may be arranged along the rotation center of the medium rotating means over the entire width of the print area of the print medium. Further, the inkjet head may have a discharge energy generating unit for discharging ink, and in this case,
It is preferable that the discharge energy generating section has an electrothermal converter that generates thermal energy.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an ink jet printer for performing printing on the outer peripheral surface of a cylindrical body is shown in FIG. 1 showing a side structure thereof, FIG. FIG. 3 showing a planar shape, FIG. 4 in which main parts in FIG. 1 are extracted and enlarged, and FIG. 5 showing an outline of a power transmission mechanism will be described in detail. The present invention can be naturally applied not only to an ink jet printer that performs printing on a print medium, but also to a print medium having a fixed radius of curvature other than a cylindrical body and a printing apparatus of another type.

The ink jet printer in this embodiment may be of a type that reads an image and copies it, such as a copying machine, but is generally connected to a computer and prints an image printed in the computer. The data is transferred and printed.

That is, a pair of screw shafts 12 and 13 arranged in a straight line are rotatably attached to the frame-shaped housing 11, and one of the screw shafts (hereinafter referred to as a driven screw shaft) 12. Can be adjusted along the direction facing the other screw shaft (hereinafter referred to as a drive screw shaft) 13. An adjusting nut 15 having a conical surface 14 at the tip is screwed to each of the screw shafts 12 and 13. In addition, in the present embodiment, three gripping jaws 17 are provided on the end plate 16 integrally provided at the distal ends of the screw shafts 12 and 13 with the axis L of the screw shafts 12 and 13 at equal intervals in the circumferential direction. The gripping jaws 17 are movably mounted in opposing directions, and each of the gripping jaws 17 is formed with a slope 18 corresponding to the conical surface 14 of the adjusting nut 15, and is sandwiched between the adjusting nut 15 and the end plate 16. . Drive screw shaft 1
The gripping jaw 17 on the third side has an axis L of the screw shafts 12 and 13.
A stopper 20 that can abut one end face of the cylindrical body 19 so that the position of the cylindrical body 19 along the direction can be always set to be constant.
Are formed on the opposite side of the end plate 16.

The gripping jaws 17 are provided with biasing means (not shown) for biasing them toward the axis L of the screw shafts 12, 13. Therefore, the adjustment nut 15 is rotated while the rotation of the screw shafts 12 and 13 is restrained, and this is
By moving to the side, the distance between the end plate 16 and the conical surface 14 of the adjusting nut 15 is reduced, and accordingly, the gripping jaw 17 causes the screw shafts 12, 13 to resist the urging force of the urging means.
Radially in a direction away from the axis L. Conversely, by rotating the adjustment nut 15 away from the end plate 16, the gripping jaw 17 is retracted toward the axis L of the screw shafts 12, 13 by the urging force of the urging means.

In the present embodiment, the position of the driven screw shaft 12 is adjusted in the direction facing the drive screw shaft 13 in accordance with the length of the cylindrical body 19 along the axial direction. By inserting the gripping jaws 17 against the inner peripheral surface of the cylindrical body 19,
And the axis L of the screw shafts 12 and 13 are automatically coaxial with each other. That is, the screw shafts 12, 13, the adjusting nut 15, the gripping jaw 1
7, etc., constitute an inwardly expanding medium gripping means according to the present invention, wherein the axis of the cylindrical body 19 and the axis L
As long as the cylindrical body 19 can be gripped so that the two are coaxial with each other, it is of course possible to adopt a medium gripping means other than this embodiment.

At the base end of the drive screw shaft 13, the driven gear 2
1, a medium drive motor 24 having a drive gear 23 meshing with a driven gear 21 via a transmission gear 22 rotatably mounted on the housing 11 is mounted on the housing 11. The medium drive motor 24, which constitutes the medium rotating means according to the present invention together with the driven gear 21, the transmission gear 22, the drive gear 23, and the like, is capable of stably driving the cylindrical body 19 at a predetermined speed, such as a stepping motor. It is desirable to adopt it.

Above the screw shafts 12 and 13, a sensor holder 28 for housing a non-contact type gap sensor 27 for detecting the distance between the ink jet head 25 and the printing surface of the cylindrical body 19, that is, the outer peripheral surface 26 is provided. A head holder 29 for accommodating a plurality of ink jet heads 25 for ejecting ink to an outer peripheral surface 26 of a cylindrical body 19 serving as a printing surface is slidably slidable in a direction facing the axis L of the screw shafts 12 and 13. A pair of supporting brackets 30 is provided. These brackets 30 have engaging pins 31 protruding from the sensor holder 28 and the head holder 29.
Sliding guide grooves 32 for slidably engaging and holding the screw shafts 12 and 1 are formed.
3 extends in a direction facing the axis L.

An annular gap adjusting plate 33 rotatably mounted on the drive screw shaft 13 so as to be coaxial with the axis L of the drive screw shaft 13 has a slanted angle with respect to the slide guide groove 32. The scroll grooves 34 having a predetermined radius of curvature extending in the inclined direction are formed at equal intervals along the circumferential direction, and the engaging pins 31 projecting from the sliding guide grooves 32 of one bracket 30 Is also engaged. A driven gear 35 of an adjustment plate drive motor 36 attached to the housing 11 meshes with a driven gear 35 formed on the outer periphery of the gap adjustment plate 33. It is preferable that the adjustment plate drive motor 36, which constitutes the adjustment plate drive means of the present invention together with the driven gear 35 and the drive gear 37, also employs a stepping motor capable of performing the same stable drive as the medium drive motor 24 described above.

Therefore, by driving the adjusting plate driving motor 36 in the normal / reverse direction, the gap adjusting plate 33 rotates in the normal / reverse direction,
The amount of screw shaft 1 corresponding to the rotation direction and rotation angle
The sensor holder 28 and each of the head holders 29 are displaced in synchronization with each other in the direction opposite to the axis L of the second and the thirteenth. Controlled. That is, the above-described engagement pin 31, sliding guide groove 32, scroll groove 34, and the like constitute a power transmission mechanism according to the present invention.

When the cylindrical body 19 is attached or detached, the gap sensor 27 and the ink jet head 25 are connected to the screw shafts 12 and 1.
In order that the engagement pin 31 is located on the outer peripheral end side of the scroll groove 34 in order to wait at the position farthest from the axis L of the third axis L, that is, the standby position, the standby position for detecting the position of the dog 38 provided on the gap adjustment plate 33 A position detection sensor 39 is attached to the housing 11. That is, by stopping the adjusting plate drive motor 36 when the standby position detection sensor 39 detects the dog 38, the gap sensor 27 and the inkjet head 25 can be positioned at the standby position.

In the present embodiment, ink (not shown) is drawn along the axis L of the screw shafts 12 and 13 so as to face the entire outer peripheral surface 26 along the axial direction of the cylindrical body 19 having the maximum length that can be mounted. And a full line type ink jet head 25 having four orifices are arranged, and color printing is possible by discharging four types of inks having different hues. Instead of such a full-line type ink jet head 25, it is of course possible to mount a serial scan type ink jet head 25 in which the ink jet head 25 scans and moves in the axial direction of the cylindrical body 19, or a print head of another structure. It is.

Next, a printing operation on the cylindrical body 19 using the ink jet printer in this embodiment will be described.

The operator first moves the driven screw shaft 12 in a direction away from the drive screw shaft 13 and fits one end of the cylindrical body 19 into the gripping jaw 17 on the drive screw shaft 13 side. In this case, one end surface of the cylindrical body 19 is pressed against the stopper 20 formed on the gripping jaw 17 to position the cylindrical body 19 along the axis L of the screw shafts 12 and 13 with respect to the ink jet printer. Accordingly, printing can be performed over the entire print area of the outer peripheral surface 26 of the cylindrical body 19 and printing can be performed at an arbitrary position on the outer peripheral surface 26 of the cylindrical body 19. Then, the driven screw shaft 12 is moved toward the drive screw shaft 13 and the gripping jaw 17 is moved to the cylindrical body 1.
9, the adjustment nut 15 is turned toward the end plate 16 while the rotation of the screw shafts 12, 13 is restrained, and the gripping jaws 17 are pressed against the inner peripheral wall of the cylindrical body 19, whereby the cylindrical body 19 is rotated. To grip. At this time, the gap sensor 2
7 and the inkjet head 25 are in a standby state at a standby position farthest from the cylindrical body 19, as indicated by a two-dot chain line in FIG.

When a print start signal is input from this state, the adjusting plate driving motor 36 rotates forward and the gap adjusting plate 33 rotates clockwise in FIG. The distance between the sensor 27 and each inkjet head 25 starts to approach. Then, when this reaches the preset optimal head gap amount,
In response to the signal from the gap sensor 27, the adjusting plate driving motor 36 stops, the medium driving motor 24 starts rotating, and the rotation of the cylindrical body 19 starts. Ink is ejected from the ejection port, and printing is performed on the outer peripheral surface 26 of the print cylinder 19 based on image information such as a print width and a print length transferred from a computer (not shown).

In this embodiment, since the ink jet head 25 is a full-line ink jet head, printing is completed when the cylindrical body 19 makes one rotation, and the medium drive motor 24 stops. In this rotation control, since the medium drive motor 24 is a stepping motor, one rotation control of the rotating body is performed by sending a predetermined pulse based on the signal of the gap sensor 27, but this rotation accuracy is improved. For,
Either a rotation angle detecting means such as a rotary encoder for detecting the rotation angle of the drive screw shaft 13 is provided, or a position index is provided on the outer peripheral surface 26 of the drive screw shaft 13 and
By providing a sensor that detects the position index for each rotation, control of the rotation angle of the cylindrical body 19 and position correction may be performed.

When printing on the cylindrical body 19 is completed, the adjusting plate drive motor 36 is driven in reverse rotation again by timer means (not shown) based on a signal from the gap sensor 27, and the gap adjusting plate 33 is moved in FIG. Rotate counterclockwise. When the standby position detection sensor 39 detects the dog 38 provided on the gap adjusting plate 33, the gap control motor stops. Thereafter, the operator removes the cylindrical body 19 and ends the printing operation.

In the present embodiment, the distance between the outer peripheral surface 26 of the cylindrical body 19 and the ink jet head 25 is directly detected, and the distance between the outer peripheral surface 26 and the ink jet head 25 is controlled based on the signal. As the detecting means, a cylindrical body 19 centered on the axis L of the screw shafts 12, 13 is used.
May be detected, and the distance between the outer peripheral surface 26 of the cylindrical body 19 and the inkjet head 25 may be controlled based on this calculation information.

In the case of a printing apparatus using such an ink jet system, the landing accuracy of ink droplets ejected from the ink jet head 25 to the cylinder 19 occupies a large specific gravity in image formation. In particular, in the full line type ink jet head 25, since the bending of the discharge direction of each discharge port crucially governs the landing accuracy, the inkjet head 25 and the cylindrical body 19 are required to maintain the landing accuracy of the ink droplets. Needs to be controlled to a predetermined distance with the outer peripheral surface 26. In the above-described embodiment, since the outer diameter of the cylindrical body 19 is detected and the approach amount of the ink jet head 25 is determined based on the signal, regardless of the outer diameter of the cylindrical body 19, a plurality of The distance between the print head and the outer peripheral surface 26 of the cylindrical body 19, that is, the head gap is always controlled to be constant.

In this embodiment, the ink jet printer for the outer peripheral surface 26 of the hollow cylindrical body 19 has been described. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can also be applied to a printing apparatus for printing on a print surface of a print medium having a predetermined radius of curvature.

In addition, the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for discharging a liquid, particularly in an ink jet system. This provides an excellent effect in an ink jet printer of a type in which a change in the state of a liquid is caused by thermal energy.
According to such a method, it is possible to achieve higher density and higher definition of the print.

The typical configuration and principle are described in, for example, US Pat. No. 4,723,129 and US Pat.
It is preferable to use the basic principle disclosed in Japanese Patent Application No. 0796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or the flow path holding the liquid. Applying at least one drive signal to the electrothermal transducer that provides a rapid temperature rise exceeding nucleate boiling corresponding to the print information, thereby generating thermal energy in the electrothermal transducer and providing a thermal effect to the inkjet head. This is effective because film boiling occurs on the surface, and consequently, bubbles in the liquid corresponding to this drive signal can be formed one-to-one. By the growth and shrinkage of the bubble, the liquid is discharged through the discharge port to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of the liquid having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. In addition,
US Patent No. 4 of the invention relating to the rate of temperature rise of the heat acting surface
By employing the conditions described in the specification of Japanese Patent No. 313124, more excellent printing can be performed.

The structure of the ink jet head is a combination of a discharge port, a flow path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. In addition, the present invention includes a configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600, which discloses a configuration in which a heat acting portion is arranged in a bent region. In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an aperture for absorbing a pressure wave of thermal energy is provided. JP-A-59-138461 which discloses a configuration corresponding to a discharge section
The effects of the present invention are effective even if the configuration is based on the above publication. That is, according to the present invention, printing can be performed reliably and efficiently regardless of the form of the inkjet head.

Further, it is preferable to add a discharge recovery means for the ink jet head, a preliminary auxiliary means, and the like as the structure of the ink jet apparatus of the present invention since the effects of the present invention can be further stabilized. Specific examples include capping means for the ink jet head, cleaning means, pressurizing or sucking means, an auxiliary heating element using an electrothermal transducer, another heating element, or a combination thereof. Examples of the heating unit include a preliminary ejection unit that performs ejection different from printing.

The type and number of ink jet heads to be mounted are, for example, not only one provided for a single color ink, but also a plurality of inks having different print colors and densities. A plurality may be provided. That is, for example, the print mode of the inkjet apparatus is not limited to the print mode of only the mainstream color such as black, but may be either an integrated inkjet head or a combination of a plurality of inkjet heads. The present invention is also very effective for an apparatus provided with at least one of the full-color print modes using mixed colors. In this case, it is also effective to discharge a processing liquid (printability improving liquid) for adjusting the printability of the ink according to the print medium from the inkjet head to the print medium.

In addition, in the embodiment of the present invention described above, a material which solidifies at room temperature or lower and softens or liquefies at room temperature may be used. In general, the temperature is controlled within the range of not more than ° C. and the temperature is controlled so that the viscosity of the liquid is in a stable ejection range. In addition, in order to positively prevent the temperature rise due to thermal energy by using it as the energy of the state change from the solid state to the liquid state, or to prevent the evaporation of the liquid,
What solidifies in a standing state and liquefies by heating may be used. In any case, the liquid is liquefied by the application of the thermal energy according to the print signal, and is liquefied only by the application of the thermal energy, such as the one from which the liquid is ejected and the one which already starts to solidify when reaching the print medium. The present invention can be applied to the case of using a material having a property. The liquid in such a case is disclosed in JP-A-54-56847.
JP-A No. 60-71260 or JP-A-60-71260, in a state in which the porous sheet is held as a liquid or solid substance in a concave portion or a through-hole and faces the electrothermal converter. Is also good. In the present invention,
The most effective one for each of the above-mentioned liquids is to execute the above-mentioned film boiling method.

In addition, the form of the printer according to the present invention is not only used as an image output terminal of an information processing apparatus such as a computer, but also a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function. It may be one that takes the form of a printing device.

[0040]

According to the printing apparatus of the present invention, the gap sensor and the print head are radially arranged so as to surround the print surface of the print medium, and the gap adjusting plate is driven and rotated based on the detection value from the gap sensor. The print head is moved relative to the bracket in the direction opposite to the rotation center of the medium rotating means so that the distance between the print head and the print surface of the print medium is kept constant. Printing can be performed directly on the print surface of the print medium without using a required method, and the printing operation on various types of print media can be simplified in a small amount of production as compared with the conventional one.

In addition, even for a print medium having a print surface having a different radius of curvature, the print head moves in the direction facing the center of curvature of the print surface to maintain a constant distance from the print surface. It is possible to perform good color printing without deviation and uneven density.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a mechanism showing a side shape of an embodiment of a printing apparatus according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a plan view of the embodiment shown in FIG. 1;

FIG. 4 is a conceptual diagram in which main parts of the embodiment shown in FIG. 1 are extracted and enlarged.

FIG. 5 is a mechanism conceptual diagram showing a moving range of a print head in the embodiment shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 housing 12 driven screw shaft 13 drive screw shaft 14 conical surface 15 adjusting nut 16 end plate 17 gripping jaw 18 slope 19 cylindrical body 20 stopper 21 driven gear 22 transmission gear 23 drive gear 24 medium drive motor 25 inkjet head 26 outer peripheral surface 27 gap Sensor 28 Sensor holder 29 Head holder 30 Bracket 31 Engagement pin 32 Sliding guide groove 33 Gap adjusting plate 34 Scroll groove 35 Follower gear 36 Adjusting plate drive motor 37 Drive gear 38 Dog 39 Standby position detection sensor L Screw axis

Claims (10)

[Claims] 1. A printing apparatus for performing printing using a print head on a print medium having a print surface having a predetermined radius of curvature, comprising: a medium gripping unit that grips the print medium; and a center of curvature of the print surface being a center of rotation. Medium rotating means for driving and rotating the medium gripping means at a predetermined speed; a bracket for slidably holding the print head in a direction opposite to a rotation center of the medium rotating means; and a medium rotating means. A gap sensor held by the bracket slidably in a direction opposite to the rotation center of the print head to detect a distance between the print head and the print surface; and a rotation center coaxial with the rotation center of the medium rotation unit. A gap adjusting plate having: an adjusting plate driving means for driving and rotating the gap adjusting plate; a gap adjusting plate and the gap; A power transmission mechanism that connects the sensor and the print head to convert the rotation of the gap adjustment plate into a linear movement of the gap sensor and the print head in a direction facing a rotation center of the medium rotating unit; A printing apparatus comprising: a control unit that controls the adjustment plate driving unit based on a detection signal from the gap sensor so that a distance between a surface and the print head is constant. 2. The power transmission mechanism includes a plurality of scroll grooves formed in the gap adjusting plate, and engagement pins projecting from the gap sensor and the print head and engaging with the scroll grooves. The printing apparatus according to claim 1, further comprising: 3. The apparatus according to claim 2, wherein the engaging pin is formed on the bracket and engages with a sliding guide groove for guiding sliding of the gap sensor and the print head with respect to the bracket. The printing device according to claim 2. 4. The printing apparatus according to claim 1, wherein the print medium is a cylindrical body. 5. The printing apparatus according to claim 4, wherein the medium gripping means has a plurality of gripping jaws abutting on an inner peripheral surface of the cylindrical body. 6. The printhead according to claim 1, wherein the printhead is an ink-jet head formed such that a discharge port for discharging ink faces a print surface of the print medium. A printing device according to claim 1. 7. The bracket according to claim 6, wherein the bracket radially supports a plurality of the inkjet heads that respectively eject inks of different hues.
A printing device according to claim 1. 8. The printing apparatus according to claim 6, wherein the discharge ports are arranged along the rotation center of the medium rotating means over the entire width of a print area of the print medium. Printing equipment. 9. The printing apparatus according to claim 6, wherein the ink jet head has a discharge energy generating unit for discharging ink. 10. The printing apparatus according to claim 9, wherein the discharge energy generating section has an electrothermal converter that generates thermal energy.