WO2018116873A1

WO2018116873A1 - Drying device and image forming device

Info

Publication number: WO2018116873A1
Application number: PCT/JP2017/044222
Authority: WO
Inventors: 隆秀岡崎
Original assignee: 富士フイルム株式会社
Priority date: 2016-12-19
Filing date: 2017-12-08
Publication date: 2018-06-28

Abstract

Provided are: a drying device capable of efficiently monitoring the traveling state of a transfer belt, and performing drying by stably transferring paper; and an image forming device. A drying device (100) is provided with: a transfer belt (110) that transfers paper (P), on which an image is formed, said paper being transferred in a state wherein at least a part thereof is sucked; a heating/drying unit (90) for drying the paper (P) by applying heat to the paper (P) being sucked and transferred by means of the transfer belt (110); and sensors (104, 106) that detect the feeding speed of the transfer belt (100), said feeding speed being in the transfer direction, and a change quantity of the transfer belt position, said change quantity being in the transfer belt width direction orthogonal to the transfer direction.

Description

Drying apparatus and image forming apparatus

The present invention relates to a drying apparatus and an image forming apparatus, and more particularly to an apparatus for heating and drying a sheet on which an image is formed and a sheet conveying technique thereof.

Patent Document 1 discloses a printer including a conveyance belt that conveys paper, a printer head that ejects ink droplets from a plurality of nozzles, and an air-heated drying device. The conveying belt is provided with a plurality of suction holes for adsorbing the paper, and the paper is adsorbed and held on the conveying belt by air suction using an adsorbing device. In the printer described in Patent Document 1, printing is performed by ejecting ink from the printer head in synchronization with the paper transport operation by feeding the transport belt. The drying device sends heated air to the printing surface of the paper to dry the paper after printing.

Further, the conveyor belt described in Patent Document 1 is provided with a marker line for detecting the speed and position of the conveyor belt, and the driving of the conveyor belt is controlled while detecting the passage of the marker line using a sensor. Is done. It is understood that “printer head” in Patent Document 1 is a term corresponding to “inkjet head” in this specification. It is understood that “printer” in Patent Document 1 is a term corresponding to “image forming apparatus” in this specification.

Patent Documents 2 and 3 disclose a technique for detecting a feeding speed of a conveyor belt using a sensor. In the present specification, the conveyor belt may be simply referred to as “belt”.

JP 2002-103598 A JP-A-6-263281 JP 2008-44767 A

In the case of an image forming apparatus that forms an image on paper using ink, wavy deformation of the paper after image formation becomes a problem. In particular, in the case of an image forming method using water-based ink, the wavy deformation of the paper can be remarkably generated. The wavy deformation of the paper is called cockle. As a countermeasure against cockle, an adsorption belt drying method is effective in which the paper after image formation is adsorbed and held on the transport belt and dried by applying heat to the paper.

However, since the conveyor belt applied to the adsorption belt drying system is affected by the heat caused by heating, the operation of the belt becomes much more unstable than that of the conveyor belt used at room temperature. Cheap. When an abnormality occurs in the feeding speed of the transport belt in the drying device that dries the paper after image formation, for example, the subsequent paper collides with the preceding paper, or the movement of the gripper transport system and the transport belt is synchronized. In the case of conveying the paper, a paper passing defect such as the paper falling off from the gripper may occur.

In addition, it is desirable that the conveyor belt in the drying device continue to run straight in parallel with the paper conveyance direction, but due to the characteristics of the conveyor belt, such as non-uniformity (distortion) in the width direction of the belt itself. As a result, the vehicle may meander or skew while traveling. When the inclination of the traveling direction of the conveying belt with respect to the sheet conveying direction becomes significant, there may be a problem that the conveying belt protrudes from the pulley and contacts other members in the apparatus. The “width direction” of the transport belt refers to a belt width direction that is a direction orthogonal to the transport direction.

If the conveyor belt of the drying device meanders, it is difficult to align the paper when stacking the paper after drying. If the sheets are stacked unevenly, problems such as adversely affecting the post-processing process or bending of the edge of the sheet may occur.

Therefore, it is desirable that the conveyance belt is kept straight within the conveyance direction of the paper while keeping the fluctuation amount of the position in the width direction within a predetermined allowable range.

In order to stably transport the paper and perform the drying process in the suction belt transport type drying device, the feed belt speed and the position change in the width direction perpendicular to the transport direction are detected. It is necessary to perform appropriate control.

At that time, the required number of sensors can be reduced as much as possible, rather than adopting a configuration in which a plurality of sensors including a sensor for detecting the feeding speed of the conveyor belt and a sensor for detecting the position in the width direction are employed. It is desirable to realize the function.

The present invention has been made in view of such circumstances. A drying apparatus and an image forming apparatus that can efficiently monitor the running state of the conveyor belt and can stably transport a sheet to perform a drying process. The purpose is to provide.

In order to achieve the above object, the present disclosure provides the following aspects of the invention.

The drying device according to the first aspect dries the paper by applying heat to the transport belt that transports the paper in a state where at least a part of the paper on which the image is formed is sucked, and the paper that is sucked and transported by the transport belt. A drying apparatus including a heat drying processing unit, a feed speed in the conveyance direction of the conveyance belt, and a sensor that detects a fluctuation amount of a position in a width direction orthogonal to the conveyance direction of the conveyance belt.

The drying device according to the first aspect can effectively suppress cockle because the paper on which the image is formed is sucked and transported by the suction belt transport method and heat is applied to the paper to perform the drying process. Moreover, since the drying apparatus of the first aspect detects the amount of change in the feed speed of the conveyor belt and the position in the width direction with the same sensor, the sensor for detecting the feed speed and the position in the width direction are detected. Compared with the configuration in which the sensors are provided separately, the feed speed information and the width direction position information can be acquired with a small number of sensors.

As a second aspect, in the drying apparatus of the first aspect, the sensor may be a non-contact type sensor.

It is preferable to use a non-contact type sensor rather than a contact type sensor. Since the contact-type sensor exerts a force on the conveyance belt at the contact position, the conveyance belt may be deformed, and the original function of “adsorbing and conveying the paper evenly” may be impaired. In this respect, the non-contact type sensor does not apply an external force to the conveyance belt and does not impair the function of the conveyance belt.

As a third aspect, in the drying apparatus according to the second aspect, the sensor may be a light sensor that uses reflected light from the transport belt or transmitted light that has passed through the transport belt.

A photoelectric conversion element is used for the optical sensor, and a signal corresponding to the intensity of reflected light or transmitted light is output. The intensity of light may be paraphrased as light quantity.

As a fourth aspect, in the drying apparatus according to the third aspect, the conveyor belt may have a mark that changes the intensity of light received by the sensor.

The mark has a two-dimensional spread on the conveyor belt, and the signal obtained from the sensor varies between the marked area and the non-marked area.

As a fifth aspect, in the drying apparatus according to the fourth aspect, the mark may be a reflection mark that reflects light, and the conveyance belt may include at least one reflection mark.

As a mark in the case of adopting a reflection type optical sensor, a reflection mark having an effect of increasing the intensity of reflected light in the mark area rather than the intensity of reflected light in the non-mark area can be used.

Depending on the material of the conveyor belt, it is possible to use an anti-reflection mark that makes the reflected light intensity of the mark area weaker than the reflected light intensity of the non-mark area as a mark when a reflective optical sensor is adopted. is there.

As a sixth aspect, in the drying device of the fourth aspect, the mark may be a light passage hole that allows light to pass therethrough, and the conveyance belt may have at least one light passage hole.

As a mark when a transmission type optical sensor is adopted, a light passage hole may be provided in the conveyor belt. In addition, from the viewpoint of durability of the transport belt, an aspect using a reflection mark is preferable to providing a light passage hole.

As a seventh aspect, in the drying apparatus according to any one of the fourth to sixth aspects, the conveyor belt has at least one mark set formed by arranging a plurality of marks in a two-dimensional array pattern. The mark set region may have a shape having a change in each of the conveyance direction and the width direction.

The two-dimensional shape including a straight line or a curve that is non-parallel to the transport direction and non-parallel to the width direction can be a shape that has a change in each of the transport direction and the width direction.

As an eighth aspect, in the drying device according to any one of the fourth aspect to the seventh aspect, the mark includes an oblique line segment that is non-parallel to the transport direction and non-parallel to the width direction as a boundary line. It can be set as the structure which has the planar view shape of a square or the closed curve which contains a curve in a boundary line.

As a ninth aspect, in the drying device according to any one of the fourth aspect to the eighth aspect, the transport belt has a belt length capable of sucking and transporting a plurality of sheets of paper simultaneously, and sucks the plurality of sheets respectively. A configuration may be adopted in which a mark is provided for each sheet suction region to be used.

As a tenth aspect, in the drying apparatus according to any one of the first aspect to the ninth aspect, a plurality of sensors may be arranged in the transport direction.

A configuration in which sensors are arranged on each of the inlet side and the outlet side of the heat drying processing unit is preferable.

As a 11th aspect, in the drying apparatus according to any one of the 1st aspect to the 10th aspect, a signal processing unit for processing a signal obtained from a sensor, wherein a feed speed in a transport direction is determined from an interval of signals obtained from the sensor. And a signal processing unit that performs processing for detecting the amount of change in the position in the width direction from at least one of the number of signals obtained from the sensor and the signal duration. .

As a twelfth aspect, in the drying device according to any one of the first aspect to the eleventh aspect, the driving device includes a driving roller and a driven roller, and the conveying belt is wound between the driving roller and the driven roller. It can be set as the structure which is an endless belt.

As a thirteenth aspect, in the drying apparatus according to the twelfth aspect, the tension difference adjusting mechanism that adjusts the belt tension difference in the width direction and the tension difference adjusting mechanism are controlled based on the fluctuation amount of the position in the width direction detected using the sensor. And a control unit that performs the operation.

As a fourteenth aspect, the conveyance belt is provided with a plurality of suction holes, a suction chamber is disposed on the opposite side of the conveyance belt from the sheet support surface, and the sheet is conveyed by the air pressure through the suction holes. It can be set as the structure made to adsorb | suck to.

As a method for adsorbing paper to the conveyor belt, a suction adsorption method using negative pressure by air suction can be adopted.

As a fifteenth aspect, in the drying apparatus according to any one of the first aspect to the fourteenth aspect, the gripper includes a gripper that grips the leading end portion of the paper and a gripper transport unit that transports the paper gripped by the gripper. A configuration can be adopted in which the sheet is conveyed in a state where a part of the sheet conveyed by the conveying unit is adsorbed to the conveyance belt.

An image forming apparatus according to a sixteenth aspect includes: an image forming unit that forms an image on paper using ink; and the drying device according to any one of the first to fifteenth aspects. Is an image forming apparatus that dries the paper on which the image is formed by a drying apparatus.

As an seventeenth aspect, in the image forming apparatus according to the sixteenth aspect, the image forming unit includes an inkjet head that discharges water-based ink, a drawing drum that is disposed to face the inkjet head and conveys paper to the inkjet head, The conveyor belt can be driven at a feed speed synchronized with the rotation of the drawing drum.

According to the present invention, it is possible to efficiently monitor the amount of change in the feed speed of the conveyor belt and the position in the width direction with a minimum number of sensors. According to the present invention, it is possible to stably transport a paper sheet after image formation and perform a drying process, and to suppress cockle.

FIG. 1 is an overall configuration diagram illustrating an example of an inkjet printing apparatus to which a drying apparatus according to an embodiment is applied. FIG. 2 is a configuration diagram illustrating an outline of the drying apparatus according to the first embodiment. FIG. 3 is a plan view showing a part of the sheet suction surface of the transport belt. FIG. 4 is a side view schematically illustrating a configuration example of the heat drying processing unit. FIG. 5 is a side view schematically showing a configuration example of the suction belt conveyance device. FIG. 6 is a perspective view of the suction belt conveyance device. FIG. 7 is a schematic plan view of the suction belt conveyance device. FIG. 8 is an enlarged view of a region around the sensing point in the transport belt. FIG. 9 is a diagram illustrating an example of another mark form. FIG. 10 is a schematic diagram showing a normal belt conveyance state. FIG. 11 is a schematic diagram illustrating a state in which a positional deviation occurs in the width direction of the transport belt and the belt is traveling in an oblique direction. FIG. 12 is a schematic diagram illustrating a state in which the positional deviation amount in the width direction is further increased from the state illustrated in FIG. 11. FIG. 13 is a table summarizing the detection operations of the sensor according to changes in reflected light intensity by the mark set illustrated in FIG. FIG. 14 is an example of a signal obtained from the sensor in a normal belt conveyance state. FIG. 15 is an example of a signal obtained from the sensor when the feeding speed of the conveyor belt is slow. FIG. 16 is an example of a signal obtained from the sensor when the position in the width direction of the conveyance belt is deviated from the normal position. FIG. 17 is an example of a signal obtained from the sensor when the mark illustrated in FIG. 8 is used and the position in the width direction of the conveyor belt is deviated from the normal position. FIG. 18 is a diagram illustrating an example of marks that are employed when the detection sensitivity of the feed rate is increased. FIG. 19 is a plan view showing a part of the transport belt. FIG. 20 is a block diagram showing a system configuration of the drying apparatus. FIG. 21 is a configuration diagram illustrating an outline of a drying apparatus according to the second embodiment. FIG. 22 is a block diagram illustrating a main configuration of a control system of the inkjet printing apparatus.

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

<< Configuration example of inkjet printing apparatus >>
FIG. 1 is an overall configuration diagram illustrating an example of an inkjet printing apparatus 1A to which a drying apparatus according to an embodiment is applied. The ink jet printing apparatus 1A includes line type ink jet heads 46C, 46M, 46Y, and 46K as print heads of the drawing unit 40, and cyan (C), magenta (M), and yellow (Y) on a sheet P that is a sheet. , And black (K) ink, and a single-pass inkjet color digital printing apparatus that prints a desired image by a single-pass method.

In this example, water-based ink is used as drawing ink. A water-based ink refers to an ink in which a coloring material such as a pigment or a dye is dissolved or dispersed in water and / or a solvent soluble in water.

1 A of inkjet printing apparatuses are provided with the paper supply part 10, the process liquid provision part 20, the process liquid drying part 30, the drawing part 40, the ink drying part 50, and the stacking part 60. FIG. The drying device according to the embodiment of the invention is used in the ink drying unit 50.

The paper feeding unit 10 feeds the paper P one by one. The paper feeding unit 10 includes a paper feeding device 12, a feeder board 14, and a paper feeding drum 16. The sheets P are placed on the sheet feed table 12A in a bundled state in which a large number of sheets are stacked. The type of the paper P is not particularly limited. For example, printing paper mainly composed of cellulose, such as high-quality paper, coated paper, and art paper, can be used.

The paper feeding device 12 takes out the bundled paper P set on the paper feed tray 12A one by one from the top and feeds it to the feeder board. The feeder board 14 conveys the paper P received from the paper feeding device 12 to the paper feeding drum 16.

The paper supply drum 16 receives the paper P fed from the feeder board 14 and conveys the received paper P to the processing liquid application unit 20.

The processing liquid application unit 20 applies the processing liquid to the paper P. The treatment liquid is a liquid having a function of aggregating, insolubilizing or thickening the color material component in the ink. The treatment liquid application unit 20 includes a treatment liquid application drum 22 and a treatment liquid application device 24.

The processing liquid coating drum 22 receives the paper P from the paper supply drum 16 and conveys the received paper P to the processing liquid drying unit 30. The treatment liquid coating drum 22 includes a gripper 23 on the peripheral surface, and grips and rotates the leading end portion of the paper P with the gripper 23, so that the paper P is wound around the peripheral surface and conveyed.

The processing liquid coating device 24 applies the processing liquid to the paper P conveyed by the processing liquid coating drum 22. The treatment liquid is applied by a roller. The method of applying the treatment liquid is not limited to the roller application method. Other methods may be applied to the treatment liquid coating apparatus 24. Examples of other systems for the treatment liquid coating apparatus 24 include coating using a blade, ejection using an inkjet system, and spraying using a spray system.

The processing liquid drying unit 30 performs a drying process on the paper P coated with the processing liquid. The processing liquid drying unit 30 includes a processing liquid drying drum 32 and a hot air blower 34. The treatment liquid drying drum 32 receives the paper P from the treatment liquid application drum 22 and conveys the received paper P to the drawing unit 40. The treatment liquid drying drum 32 includes a gripper 33 on the peripheral surface. The treatment liquid drying drum 32 conveys the paper P by gripping and rotating the leading end of the paper P with the gripper 33.

The hot air blower 34 is installed inside the processing liquid drying drum 32. The hot air blower 34 blows hot air on the paper P conveyed by the processing liquid drying drum 32 to dry the processing liquid.

The drawing unit 40 includes a drawing drum 42, a head unit 44, and an image reading device 48. The drawing drum 42 receives the paper P from the processing liquid drying drum 32 and conveys the received paper P to the ink drying unit 50. The drawing drum 42 includes a gripper 43 on the peripheral surface, and the gripper 43 grips and rotates the leading end of the paper P, so that the paper P is wound around the peripheral surface and conveyed. The drawing drum 42 includes a suction mechanism (not shown), and transports the paper P wound around the circumferential surface while attracting the sheet P to the circumferential surface. A negative pressure is used for the adsorption. The drawing drum 42 has a large number of suction holes on the peripheral surface, and the sheet P is sucked onto the peripheral surface of the drawing drum 42 by suction from the inside of the drawing drum 42 through the suction holes.

The head unit 44 includes ink jet heads 46C, 46M, 46Y, and 46K. The ink jet head 46C is a recording head that discharges cyan (C) ink droplets. The inkjet head 46M is a recording head that ejects magenta (M) ink droplets. The inkjet head 46Y is a recording head that discharges yellow (Y) ink droplets. The inkjet head 46K is a recording head that ejects black (K) ink droplets. Each of the inkjet heads 46C, 46M, 46Y, and 46K is supplied with ink from an ink tank (not shown) that is an ink supply source of a corresponding color via a pipe path (not shown).

Each of the inkjet heads 46C, 46M, 46Y, and 46K is composed of a printable line head by a single scan on the paper P conveyed by the drawing drum 42, that is, by a single pass method. Ink jet heads 46 C, 46 M, 46 Y, 46 K are arranged such that each nozzle surface faces the peripheral surface of drawing drum 42. The ink jet heads 46C, 46M, 46Y, and 46K are arranged at regular intervals along the conveyance path of the paper P by the drawing drum 42.

Although not shown in FIG. 1, a plurality of nozzles serving as ink ejection openings are two-dimensionally arranged on the nozzle surfaces of the inkjet heads 46C, 46M, 46Y, and 46K. “Nozzle surface” refers to an ejection surface on which nozzles are formed, and is synonymous with terms such as “ink ejection surface” or “nozzle formation surface”. A nozzle arrangement of a plurality of nozzles arranged two-dimensionally is called a “two-dimensional nozzle arrangement”.

Each of the inkjet heads 46C, 46M, 46Y, and 46K can be configured by connecting a plurality of head modules in the paper width direction. The paper width here refers to the paper width in a direction orthogonal to the conveyance direction of the paper P. Each of the inkjet heads 46C, 46M, 46Y, and 46K is a nozzle capable of recording an image with a specified recording resolution in one scan of the entire recording area of the paper P in the paper width direction orthogonal to the conveyance direction of the paper P. This is a line type recording head having columns. Such a recording head is also called a “full line type recording head” or a “page wide head”.

The specified recording resolution may be a recording resolution predetermined by the inkjet printing apparatus 1A, or a recording resolution set by user selection or by automatic selection by a program corresponding to the printing mode. Also good. The recording resolution can be set to 1200 dpi, for example. “Dpi” means dot per inch and is a unit notation representing the number of dots (points) per inch. One inch is 25.4 millimeters [mm].

The paper width direction perpendicular to the paper P transport direction may be referred to as the nozzle row direction of the line head, and the paper P transport direction may be referred to as the nozzle row vertical direction.

In the case of an inkjet head having a two-dimensional nozzle array, the projection nozzle array in which the nozzles in the two-dimensional nozzle array are projected (orthographically projected) along the nozzle array direction achieves the maximum recording resolution in the nozzle array direction. It can be considered that the nozzle density is equivalent to a single nozzle row in which each nozzle is arranged at approximately equal intervals. The “substantially equidistant” means that the droplet ejection points that can be recorded by the ink jet printing apparatus are substantially equidistant. For example, the concept of “equally spaced” includes a case where the distance is slightly different in consideration of manufacturing errors and / or movement of droplets on the medium due to landing interference. The projection nozzle row corresponds to a substantial nozzle row. Considering the projection nozzle row, it is possible to associate a nozzle number representing the nozzle position with each nozzle in the arrangement order of the projection nozzles arranged along the nozzle row direction.

The nozzle arrangement form in each of the inkjet heads 46C, 46M, 46Y, and 46K is not limited, and various nozzle arrangement forms can be adopted. For example, instead of a matrix-like two-dimensional array, a linear array of lines, a V-shaped nozzle array, a polygonal nozzle array such as a W-shape with a V-shaped array as a repeating unit, and the like are also possible. It is.

The ink droplets are ejected from at least one of the inkjet heads 46C, 46M, 46Y, and 46K toward the paper P conveyed by the drawing drum 42, and the ejected liquid droplets adhere to the paper P. An image is formed on the paper P. The drawing unit 40 including the inkjet heads 46C, 46M, 46Y, and 46K corresponds to an example of an image forming unit.

The drawing drum 42 functions as a means for moving the inkjet heads 46C, 46M, 46Y, 46K and the paper P relative to each other. The drawing drum 42 corresponds to a form of relative moving means for moving the paper P relative to the inkjet heads 46C, 46M, 46Y, and 46K. The ejection timings of the inkjet heads 46C, 46M, 46Y, and 46K are synchronized with a rotary encoder signal obtained from a rotary encoder installed on the drawing drum 42. In FIG. 1, the rotary encoder is not shown. The ejection timing is the timing at which ink droplets are ejected, and is synonymous with the droplet ejection timing.

In this example, the configuration using four colors of CMYK ink is exemplified, but the combination of ink color and number of colors is not limited to this embodiment, and light ink, dark ink, special color ink, etc. are used as necessary. May be added. For example, a configuration in which an inkjet head that ejects light-colored ink such as light cyan or light magenta is added, or a configuration in which an inkjet head that ejects a special color ink such as green or orange is added. Also, the arrangement order of the ink jet heads for each color is not particularly limited.

The image reading device 48 is a device that optically reads an image recorded on the paper P by the ink jet heads 46C, 46M, 46Y, and 46K, and generates electronic image data indicating the read image. The image reading device 48 includes an imaging device that captures an image recorded on the paper P and converts it into an electrical signal indicating image information. In addition to the imaging device, the image reading device 48 may include an illumination optical system that illuminates a reading target and a signal processing circuit that processes a signal obtained from the imaging device and generates digital image data.

The image reading device 48 is preferably configured to read a color image. In the image reading device 48 of this example, for example, a color CCD linear image sensor is used as an imaging device. CCD is an abbreviation for Charge-Coupled Device and refers to a charge coupled device. The color CCD linear image sensor is an image sensor in which light receiving elements having color filters of R (red), G (green), and B (blue) colors are arranged linearly. Instead of the color CCD linear image sensor, a color CMOS linear image sensor can be used. CMOS is an abbreviation for Complementary Metal Oxide Semiconductor and refers to a complementary metal oxide semiconductor.

The image reading device 48 reads an image on the paper P while the paper P is being conveyed by the drawing drum 42. The image reading apparatus installed in the paper conveyance path in this way is sometimes called an “inline scanner” or “inline sensor”. The image reading device 48 may be a camera.

The image on the paper P is read when the paper P on which the image is recorded using at least one of the inkjet heads 46C, 46M, 46Y, and 46K passes through the reading area of the image reading device 48. As an image to be recorded on the paper P, in addition to a user image to be printed specified in a print job, a defective nozzle detection pattern for inspecting the ejection state of each nozzle, a test pattern for print density correction, and print density unevenness correction Test patterns, and various other test patterns.

The print image is inspected based on the read image data read by the image reading device 48, and the presence or absence of image quality abnormality is determined. Further, based on the data of the read image read by the image reading device 48, information such as image density and ejection failure of the ink jet heads 46C, 46M, 46Y, and 46K is obtained.

The ink drying unit 50 performs a drying process on the paper P on which the image is formed by the drawing unit 40. The ink drying unit 50 includes a chain gripper 70, a paper guide 80, and a heat drying processing unit 90.

The chain gripper 70 receives the paper P from the drawing drum 42 and conveys the received paper P to the stacking unit 60. The chain gripper 70 includes a pair of endless chains 72 that travel along a predetermined travel path, and the paper P is transported in a predetermined state in a state where the leading end portion of the paper P is gripped by the grippers 74 provided in the pair of chains 72. Transport along the route. A plurality of grippers 74 are provided in the chain 72 at regular intervals.

The chain gripper 70 of this example includes a first sprocket 71A, a second sprocket 71B, a chain 72, and a plurality of grippers 74, and a pair of the first sprocket 71A and the second sprocket 71B The endless chain 72 is wound around. In FIG. 1, only one of the pair of first sprocket 71A and second sprocket 71B and the pair of chains 72 is shown.

The chain gripper 70 has a structure in which a plurality of grippers 74 are arranged at a plurality of positions in the feed direction (length direction) of the chain 72. The chain gripper 70 has a structure in which a plurality of grippers 74 are disposed between the pair of chains 72 along the width direction in the paper width direction. FIG. 1 shows only one gripper 74 among the plurality of grippers 74 disposed between the pair of chains 72.

The transport path of the paper P by the chain gripper 70 includes a horizontal transport area for transporting the paper P along the horizontal direction, and an inclined transport area for transporting the paper P obliquely upward from the end of the horizontal transport area. The horizontal conveyance area is called a first conveyance section, and the inclined conveyance area is called a second conveyance section.

The paper guide 80 is a mechanism for guiding the conveyance of the paper P by the chain gripper 70. The paper guide 80 includes a first paper guide 82 and a second paper guide 84. The first paper guide 82 guides the paper P transported in the first transport section of the chain gripper 70. The second paper guide 84 guides the paper conveyed in the second conveyance section subsequent to the first conveyance section.

Although the detailed structure of the first paper guide 82 is not shown in FIG. 1, a suction belt conveyance device is used as the first paper guide 82. The suction belt conveyance device is a device that conveys the paper P by feeding the conveyance belt in a state where the paper P is adsorbed to an endless conveyance belt.

The heat drying processing unit 90 applies heat to the paper P on which the image is formed by the drawing unit 40 to evaporate the solvent of the ink, thereby drying the paper P. The heating / drying processing unit 90 is, for example, a hot air blowing unit, is arranged to face the first paper guide 82, and blows hot air on the paper P conveyed by the chain gripper 70.

A detailed description of the configuration of the drying device including the first paper guide 82 using the suction belt conveyance device and the heat drying processing unit 90 will be given later.

The stacking unit 60 includes a stacking device 62 that receives and stacks the paper P conveyed from the ink drying unit 50 by the chain gripper 70. The chain gripper 70 releases the paper P at a predetermined stacking position. The stacking device 62 includes a stacking tray 62A, receives the paper P released from the chain gripper 70, and stacks it in a bundle on the stacking tray 62A. The stacking unit 60 corresponds to a paper discharge unit.

<Drying apparatus of the first embodiment>
FIG. 2 is a configuration diagram illustrating an outline of the drying apparatus according to the first embodiment. 2, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 2, the image reading device 48, the first sprocket 71A, and the second sprocket 71B are not shown for simplification.

As shown in FIG. 2, the drying device 100 applied to the ink drying unit 50 includes a heat drying processing unit 90, a suction belt conveyance device 102, and

sensors

104 and 106. The suction belt conveyance device 102 includes a conveyance belt 110, a driving roller 112, a driven roller 114, and a suction chamber 116. The driving roller 112 and the driven roller 114 correspond to pulleys. The conveyor belt 110 is an endless belt and is wound between the driving roller 112 and the driven roller 114. The conveyor belt 110 may be simply referred to as a “belt”.

The belt surface facing the outside of the conveyor belt 110 wound around the driving roller 112 and the driven roller 114 is referred to as a first surface of the conveyor belt 110. The first surface of the conveyor belt 110 can be a paper support surface that can come into contact with the paper P. A surface opposite to the first surface of the conveyor belt 110, that is, a belt surface facing the inside of the conveyor belt 110 wound around the driving roller 112 and the driven roller 114 is referred to as a second surface of the conveyor belt 110.

FIG. 3 is a plan view showing a part of the sheet suction surface of the conveyor belt 110. The y direction in FIG. 3 is the belt feeding direction. The y direction may be referred to as a “transport direction”. The x direction in FIG. 3 is a direction orthogonal to the y direction and indicates the width direction of the transport belt 110. The x direction may be referred to as the “width direction”. As shown in FIG. 3, a plurality of suction holes 120 are formed in the conveyor belt 110. The plurality of suction holes 120 are preferably arranged in a regular pattern in the sheet suction area of the conveyor belt 110.

The suction chamber 116 shown in FIG. 2 is arranged on the second surface side of the conveyor belt 110, that is, on the back surface side of the conveyor belt 110. The suction chamber 116 is connected to an exhaust pump (not shown). A vacuum pump can be used as the exhaust pump. By sucking air from the suction chamber 116 by an exhaust pump (not shown) to create a negative pressure in the suction chamber 116 and sucking air from the suction hole 120 of the transport belt 110, the paper P is subjected to the action of air pressure. Adsorbed on one surface. The suction chamber 116 corresponds to an example of a suction chamber.

The paper P on which an image is formed by the drawing unit 40 is transferred from the drawing drum 42 to the chain gripper 70, and is placed on the transport belt 110 with the leading end of the paper P being gripped by the gripper 74. 110 is adsorbed. The chain gripper 70 corresponds to an example of a gripper transport unit.

The chain gripper 70 conveys the gripper 74 in synchronization with the rotation speed of the drawing drum 42. The drive roller 112 is rotationally driven so that the conveyor belt 110 travels in accordance with the feed speed of the gripper 74 by the chain gripper 70.

The conveyor belt 110 is fed at approximately the same speed as the gripper 74. The feed speed of the conveyor belt 110 and the feed speed of the gripper 74 do not necessarily need to be completely matched, and there may be a slight speed difference.

Depending on the size of the paper P and / or the stiffness of the paper P, the speed difference between the transport belt 110 and the gripper 74 may be different. If the speed of the transport belt 110 is slightly lower than the speed of the gripper 74, the paper P can be transported while applying a pulling force. Conversely, when the speed of the transport belt 110 becomes faster than the speed of the gripper 74, the transport belt 110 advances while pushing the paper P in the transport direction.

The conveyance belt 110 has a belt length that can adsorb a plurality of sheets P at the same time. The conveyance belt 110 shown in FIG. 2 has a belt length that can adsorb two sheets of paper P at the same time, but the belt length of the conveyance belt 110 can be designed as appropriate, and three sheets at the same time. A form capable of adsorbing the above paper P is also possible.

The sensor 104 is a non-contact sensor that detects the feed speed and the position in the width direction of the conveyor belt 110. The sensor 106 is also a non-contact type sensor that detects the feed speed of the conveyor belt 110 and the position in the width direction. As the

sensors

104 and 106, reflective optical sensors can be used. The reflection type optical sensor includes a light emitting element and a light receiving element, receives reflected light from an object, and outputs an electrical signal corresponding to the amount of received light. Not only the reflective optical sensor but also a transmissive optical sensor may be used as the

sensors

104 and 106. The transmission type optical sensor includes a light projector and a light receiver that are arranged to face each other, and the light transmitted from the light projector is received by the light receiver to output an electrical signal corresponding to the amount of light received. In the present embodiment, a case where the

sensors

104 and 106 are reflection type optical sensors will be described as an example. The

sensors

104 and 106 correspond to an example of a plurality of sensors arranged in the transport direction.

The sensor 104 is disposed on the outlet side of the heat drying processing unit 90. The sensor 106 is disposed on the inlet side of the heat drying processing unit 90. In the present embodiment, an example in which two

sensors

104 and 106 are provided is shown, but at least one sensor for detecting the feed speed and the position in the width direction of the conveyor belt 110 is sufficient. A configuration in which one of the two

sensors

104 and 106 is omitted is also possible.

FIG. 4 is a side view schematically showing a configuration example of the heat drying processing unit 90. The heat drying processing unit 90 includes an infrared heater 130 as a heat source and a blower 132. The blower device 132 of this example includes an air chamber 134 and a plurality of blower nozzles 136. Dry air is supplied to the air chamber 134 via a gas pipe (not shown).

A plurality of blower nozzles 136 are arranged on the bottom surface of the air chamber 134. Each of the plurality of blowing nozzles 136 communicates with the air chamber 134. The plurality of blower nozzles 136 are arranged at regular intervals along the paper conveyance direction, and the infrared heater 130 is arranged between the blower nozzles 136.

Dry air introduced into the air chamber 134 is blown out from each blowing nozzle 136. The blower 132 may include a pressure control mechanism (not shown) that adjusts the pressure of the dry air introduced into the air chamber 134. The dry air blown out from the blower nozzle 136 is not limited to dry air, and may be compressed air or ambient air. Moreover, you may use not only air but inert gas, such as nitrogen gas.

The configuration of the heat drying processing unit 90 is not limited to the example of FIG. 4 and various forms are possible. For example, the heat drying processing unit 90 may include a fan that blows air heated by a heat source onto the paper P. As an example of the heating and drying processing unit 90 in which an infrared heater that is a heat source and a fan are combined, a configuration in which an infrared heater that is a heat source is arranged on an air blowing path by the fan can be adopted to blow out warm air.

FIG. 5 is a side view schematically showing a configuration example of the suction belt conveyance device 102. In FIG. 5, the same elements as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. A first oil flow path 142 is provided in the shaft center portion of the drive roller 112 for flowing temperature adjusting oil. Similarly, a second oil passage 144 for flowing temperature adjusting oil is provided at the axial center of the driven roller 114.

The oil adjusted to a specified temperature by a temperature adjusting device (not shown) is supplied to the first oil channel 142 and the second oil channel 144 via an oil pipe (not shown). The temperature of the oil for temperature adjustment is set to a specified temperature in the range of 70 ° C. to 110 ° C., for example. As an example, the temperature of the oil for temperature adjustment can be set to 100 ° C.

When the driving roller 112 and the driven roller 114 are heated by the temperature adjusting oil, heat is transmitted to the conveyor belt 110, and the conveyor belt 110 is heated. By heating the conveyor belt 110, the drying process can be efficiently performed in combination with the heating and drying process by the heating and drying processing unit 90.

The suction belt conveyance device 102 includes a first guide roller 152 and a second guide roller 154 between the driving roller 112 and the driven roller 114. The first guide roller 152 and the second guide roller 154 serve to define the travel path of the transport belt 110, and in particular, serve to define the height of the paper transport surface of the transport belt 110.

The first guide roller 152 is disposed near the drive roller 112. The second guide roller 154 is disposed near the driven roller 114. The conveyor belt 110 is wound around the first guide roller 152 and the second guide roller 154. The back surface (second surface) of the conveyor belt 110 is in contact with the first guide roller 152 and the second guide roller 154.

The suction chamber 116 is disposed between the first guide roller 152 and the second guide roller 154 in the travel path of the conveyor belt 110. The suction chamber 116 of this example is divided into three sections in the paper transport direction. Each of the first chamber 116A, the second chamber 116B, and the third chamber 116C is connected to an exhaust pump via an exhaust pipe (not shown). It is preferable that the suction pressure can be adjusted for each section of the first chamber 116A, the second chamber 116B, and the third chamber 116C. The number of sections of the suction chamber 116 is not limited to the three illustrated sections, and can be designed to an arbitrary number of one or more.

FIG. 6 is a perspective view of the suction belt conveyance device 102. A belt tension is applied between the driving roller 112 and the driven roller 114 in a direction parallel to the belt feeding direction. For example, the belt tension can be adjusted by a mechanism that adjusts the position of the rotation axis of the driven roller 114 in the y direction. By applying an appropriate belt tension to the conveyor belt 110 and stretching the conveyor belt 110 and rotating the driving roller 112, the conveyor belt 110 can be sent stably.

In the normal conveyance state, the rotation speed of the drive roller 112 and the feeding speed of the conveying belt 110 are the same, and the conveying speed of the gripper 74 and the feeding speed of the conveying belt 110 are substantially the same.

However, there is a case where the belt tension is lowered due to some factor or the conveyance belt 110 slips (slip), and the rotation speed of the driving roller 112 is reduced due to the belt tension reduction and / or the conveyance belt 110 slipping. There may be cases where the feed speeds of the conveyor belt 110 do not match.

In such a case, the difference between the conveying speed of the gripper 74 and the feeding speed of the conveying belt 110 becomes larger than the allowable range, and the paper P falls off the gripper 74 and falls onto the conveying belt 110, or the subsequent The sheet P may collide with the preceding sheet P or the like, and paper passing failure may occur.

Further, regarding the belt tension, when a tension difference occurs in the belt width direction, the conveyor belt 110 is skewed or meandered. In order to improve such a situation, the drying apparatus 100 of the present embodiment manages the tension difference in the width direction of the conveyor belt 110 so that the position in the width direction does not fluctuate, that is, the belt does not meander. Control belt tension.

In addition, as a means for keeping the variation in the position in the width direction within the allowable range, a method of regulating the belt movement itself using a rubber material conveyor belt having a V-shaped cross section called “V guide” is adopted. It is also possible to do. However, it is difficult to manufacture such a belt, and there is a problem that the shape of the belt is affected, for example, the rubber is worn and it is necessary to periodically replace it, or the belt is deformed due to wear. .

In this regard, the conveyor belt 110 of the present embodiment employs a metal belt manufactured by processing a metal plate from the viewpoint of wear resistance and ease of manufacture. The conveyor belt 110 can be manufactured, for example, by joining a plurality of plates each having a plurality of suction holes 120 formed in a thin metal plate and joining them endlessly by welding or the like according to the belt length. it can.

FIG. 7 is a schematic plan view of the suction belt conveyance device 102. The conveyor belt 110 is provided with a mark 160 that changes the intensity of light received by the sensors 104 and 106 (see FIGS. 2 and 5). The mark 160 is a sensing mark observed by the

sensors

104 and 106, and is, for example, an identification mark formed by a reflective tape, a hole, a colored sticker, or the like that changes the reflected light intensity. Although a triangular mark 160 is shown in FIG. 7, the mark 160 is not limited to the example of FIG. 7 as long as it has a two-dimensional shape.

The mark 160 is arranged at the end of the conveyance belt 110 in the width direction. That is, the mark 160 is provided at an end in the width direction corresponding to the outside of the sheet suction range 162 in the transport belt 110. In FIG. 7, black circles denoted by reference numeral 204 represent sensing points that are observation positions by the sensor 104 (see FIGS. 2 and 5). In FIG. 7, the peripheral area of the sensing point 204 is surrounded by a broken line and indicated by a reference numeral 164.

In FIG. 7, black circles denoted by reference numeral 206 represent sensing points that are observation positions by the sensor 106 (see FIGS. 2 and 5). In FIG. 7, the peripheral area of the sensing point 204 is surrounded by a broken line and indicated by reference numeral 166.

The sensing points 204 and 206 can be determined at appropriate positions in the belt region where the belt tension is applied. Sensing point 204 is preferably near drive roller 112. More preferably, the sensing point 204 is near the first guide roller 152 (see FIGS. 2 and 5).

The sensing point 206 is preferably near the driven roller 114. More preferably, the sensing point 206 is near the second guide roller 154 (see FIGS. 2 and 5).

As described with reference to FIG. 2, a configuration in which the operation state of the conveyance belt 110 is detected at two locations on the inlet side and the outlet side of the heat drying processing unit 90 is preferable.

When the mark 160 passes the sensing point 204 along with the feeding operation of the transport belt 110, the intensity of the reflected light incident on the sensor 104 changes, and a signal corresponding to the change in the reflected light intensity is output from the sensor 104.

Similarly, when the mark 160 passes the sensing point 206, the intensity of reflected light incident on the sensor 106 changes, and a signal corresponding to the change in reflected light intensity is output from the sensor 106. The mark 160 constituted by a reflective tape or the like corresponds to an example of a reflective mark.

Further, in a form using a transmissive optical sensor, a mark constituted by a hole through which light passes corresponds to an example of a light passage hole.

It is preferable to provide the marks 160 at a plurality of locations in the feeding direction on the conveyor belt 110. A distance Y [mm] that is an arrangement interval of the marks 160 can be designed to an appropriate value. For example, one mark 160 may be attached to one sheet of paper P.

The detection operation by the

sensors

104 and 106 is common. Hereinafter, although the operation of the sensor 106 will be described, the operation of the sensor 104 is also the same.

<Method for Detecting Feed Speed and Width Position of Conveyor Belt 110>
FIG. 8 is an enlarged view of an area around the sensing point 206 in the transport belt 110. The conveyor belt 110 has the same mark 160 for every fixed distance Y millimeter [mm] in the belt feeding direction. When the detection light of the sensor 106 enters the area of the mark 160, the reflected light intensity changes. If the feed speed of the conveyor belt 110 is v millimeters per second [mm / s], the reflected light intensity changes due to the mark 160 passing through the sensing point 206 occurs every Y / v seconds.

FIG. 9 is a diagram showing an example of another mark form. 9, elements that are the same as or similar to those shown in FIG. 8 are given the same reference numerals, and descriptions thereof are omitted.

9 is provided with a mark set 182 in which a plurality of circular marks 180 are arranged in a two-dimensional arrangement pattern, instead of the triangular mark 160. The mark set 182 illustrated in FIG. 9 is a set of marks in which six circular marks 180 having the same shape are arranged in a triangular arrangement pattern. The circular marks 180 constituting the mark set 182 are preferably arranged at a certain distance L millimeter [mm] in the belt feeding direction.

When the detection light of the sensor 106 enters the area of the mark set 182 that spreads in two dimensions, the reflected light intensity changes.

When the feed speed of the conveyor belt 110 fluctuates, the interval of signals obtained from the sensor 106 changes. Further, when the position in the width direction of the conveyor belt 110 varies, the time length of the signal obtained from the sensor 106 and / or the number of signals changes.

FIG. 10 is a schematic diagram showing a normal belt conveyance state. FIG. 11 is a schematic diagram illustrating a state in which a positional deviation occurs in the width direction of the conveyor belt 110 and the belt is traveling in an oblique direction. FIG. 12 is a schematic diagram illustrating a state in which the positional deviation amount in the width direction is further increased from the state illustrated in FIG. 11.

The detection operation of the sensor 106 according to the change in reflected light intensity by the mark set 182 is summarized in the table of FIG.

The “change in reflected light intensity” in the table shown in FIG. 13 is observed as a pulse of a detection signal output from the sensor 106 when the mark 180 passes the sensing point 206.

The “determined time interval” refers to a predetermined time interval specified by calculation from the normal conveyance speed and the arrangement interval (distance Y) of the mark set 182.

The “determined time length” refers to a predetermined time length specified by calculation from a normal conveyance speed and a normal position in the width direction. The signal continuation time of the detection signal output from the sensor 106 corresponds to “a time during which the reflected light intensity changes”.

FIG. 14 is an example of a signal obtained from the sensor 106 in a normal belt conveyance state. The horizontal axis represents time, and the vertical axis represents voltage. In the example of FIG. 14, an example in which a detection signal is output from the sensor 106 during a period in which the reflected light intensity is strong due to the mark 180 is shown.

For normal belt conveyance state, the sensor 106 outputs a pulse detection signal at regular time intervals T _1. Further, each detection signal in this case is a signal duration W ₁ having a fixed time length.

FIG. 15 is an example of a signal obtained from the sensor 106 when the feed speed of the conveyor belt 110 becomes slow. Feed speed of the conveyor belt 110, becomes slower than the normal feed speed for some reason, the time interval T ₂ of the detection signals obtained from the sensor 106 is longer than the time interval T ₁ described in FIG. 14.

Conversely, the feed speed of the conveyor belt 110, becomes faster than the normal feed speed for some reason, the time interval of the detection signal obtained from the sensor 106, it is shorter than the time interval T ₁ described in FIG. 14.

FIG. 16 is an example of a signal obtained from the sensor 106 when the position in the width direction of the conveyance belt 110 is deviated from the normal position. Detection signals S ₁ in FIG. 16 represents the signal obtained by the normal state shown in FIG. 10. Detection signal S ₂ in FIG. 16 represents the signal obtained in the state shown in FIG. 12. Signal duration _{W 2} of the detection signal _{S 2} is shorter than the signal duration _{W 1} of the detection signal _{S 1.}

Detection signal S ₃ and S ₄ in FIG. 16 represents the signal obtained in the state shown in FIG. 12. In the state of FIG. 12, since two marks 180 arranged in the y direction pass through the sensing point 206 continuously in one mark set 182, two marks corresponding to changes in reflected light intensity due to the respective marks 180. The detection signals S ₃ and S ₄ are obtained continuously.

When the abnormal feed rate and the positional deviation in the width direction occur at the same time, the phenomenon described in FIG. 15 and the phenomenon described in FIG. 16 are observed in combination. A change in feed speed can be detected from the signal interval, and a variation in position in the width direction can be detected from the number of signals and / or the signal duration.

10 to 16, the example in which the mark set 182 shown in FIG. 9 is used has been described, but the case of using the mark 160 shown in FIG. 8 can be similarly understood.

FIG. 17 shows an example of a signal obtained from the sensor 106 when the mark 160 shown in FIG. 8 is used and the position in the width direction of the conveyor belt 110 is deviated from the normal position. In the case of the triangular mark 160, the signal continuation time (the signal time length) of the detection signal changes due to the displacement in the width direction of the conveyor belt 110.

Detection signal S ₅ in FIG. 17 represents the signal obtained by the normal belt conveying state. Detection signal S ₆ in FIG. 17 represents the signal obtained in the state corresponding to FIG. 11. Signal duration _{W 6} of the detection signal _{S 6} is longer than the signal duration _{W 5} of the detection signal _{S 5.} Detection signal S ₇ in FIG. 17 represents the signal obtained in the state corresponding to FIG. 12. Signal duration _{W 7} of the detection signal _{S 7} is longer than the signal duration _{W 6} of the detection signal _{S 6.}

The change in the feed rate can be detected from the signal interval obtained from the sensor 106, and the amount of change in the position in the width direction can be detected from the signal duration.

The detection sensitivity for the feed rate and the amount of change in the position in the width direction can be changed by the triangular shape of the mark 160. For example, as shown in FIG. 18, by using a vertically long triangular mark 160 along the belt feeding direction, the detection sensitivity can be increased with respect to a change in the position in the width direction.

Further, by narrowing the pitch in the y direction of the marks 180 in the mark set 182 shown in FIG. 9, that is, by reducing the distance L [mm] in FIG. be able to.

[Example of Arrangement Form of Mark 160]
A distance Y [mm] that is an arrangement interval of the marks 160 can be designed to an appropriate value. The marks 160 are preferably arranged at a plurality of locations in the feeding direction of the conveyor belt 110. It is preferable that one mark 160 is attached to one sheet suction area. Of course, a configuration in which one mark 160 is attached to two sheets of suction area, and a configuration in which one mark 160 is attached to three sheets of suction area are also possible.

FIG. 19 is a plan view showing a part of the conveyor belt 110. The conveyance belt 110 shown in FIG. 19 has a belt length that can adsorb and convey three sheets of paper P at the same time. FIG. 9 shows three

sheet suction areas

170A, 170B, and 170C arranged along the belt feeding direction. One sheet P is sucked and held for each of the

sheet suction areas

170A, 170B, and 170.

As shown in FIG. 19, in the case of the conveyor belt 110 on which three sheets of paper P can be placed simultaneously, it is preferable to provide one mark 160 for each sheet of paper P. That is, it is preferable to provide the mark 160 for each of the

paper suction areas

170A, 170B, and 170C.

The same applies when the mark set 182 is used instead of the mark 160.

[Sensor placement position]
Immediately after the driven roller 114 is a position where the temperature of the conveyor belt 110 is most stable due to temperature control. On the other hand, immediately before the driving roller 112, it is the position where the belt tension is most applied and after the heat drying processing unit 90 is exited, and the temperature difference can be the largest. Therefore, a mode in which the sensor 106 is disposed immediately after the driven roller 114 on the inlet side of the heating and drying processing unit 90 and the sensor 104 is disposed immediately before the driving roller 112 on the outlet side of the heating and drying processing unit 90 is preferable. . In the case where the sensor is disposed only at one of the inlet side and the outlet side of the heat drying processing unit 90, a form in which the sensor is disposed on the outlet side of the heat drying processing unit 90 is preferable.

[System configuration of drying equipment]
FIG. 20 is a block diagram showing a system configuration of the drying apparatus 100. The drying apparatus 100 includes a signal processing unit 210 that processes signals obtained from the

sensors

104 and 106, a control unit 212, a driving motor 214 that is a power source of the driving roller 112, a heating and drying processing unit 90, and a tension difference adjustment. Mechanism 220.

The signal processing unit 210 performs processing for detecting a change in the feeding speed in the conveyance direction from the interval of signals obtained from the

sensors

104 and 106, and at least one of the number of signals obtained from the

sensors

104 and 106 and the signal duration time. To detect the amount of change in the position in the width direction.

Information indicating the processing result of the signal processing unit 210 is sent from the signal processing unit 210 to the control unit 212. Note that the processing function of the signal processing unit 210 may be included in the control unit 212.

The tension difference adjusting mechanism 220 is a mechanism for adjusting the belt tension difference in the width direction of the conveyor belt 110. The tension difference adjusting mechanism 220 includes a first tension applying mechanism 221 that applies tension to one end side of both ends of the conveyance belt 110 in the width direction, and a second tension applying mechanism that applies tension to the other end side. 222. The belt tension difference in the width direction can be adjusted by the first tension applying mechanism 221 and the second tension applying mechanism 222.

The control unit 212 controls the drive motor 214, the heat drying processing unit 90, and the tension difference adjusting mechanism 220. The control unit 212 urgently stops the apparatus when the fluctuation in the feed rate detected by the

sensors

104 and 106 exceeds a specified allowable range.

The control unit 212 may control the rotation of the drive motor 214 according to the feed speed detected by the

sensors

104 and 106. The control unit 212 controls the tension difference adjustment mechanism based on the variation amount of the position in the width direction detected by the

sensors

104 and 106. For example, when the fluctuation amount of the position in the width direction detected by the

sensors

104 and 106 exceeds a predetermined allowable value, the control unit 212 performs control to adjust the belt tension.

<Drying apparatus of the second embodiment>
FIG. 21 is a configuration diagram illustrating an outline of a drying apparatus according to the second embodiment. In FIG. 21, the same elements as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. Instead of the drying apparatus 100 shown in FIG. 2, a drying apparatus 230 shown in FIG. 21 can be employed.

21 is provided with a transfer drum 240 and a belt conveyance unit 252 instead of the chain gripper 70. The second embodiment shown in FIG. The transfer drum 240 has a gripper 242. The gripper 242 of the transfer drum 240 receives the paper P from the gripper 43 of the drawing drum 42 and transfers the paper P to the transport belt 110 of the suction belt transport device 102. When the gripper 242 releases the grip of the paper P, the paper P is attracted and held on the transport belt 110. The paper P placed on the transport belt 110 is transported by the transport belt 110.

The belt conveyance unit 252 disposed at the subsequent stage of the suction belt conveyance device 102 has the same structure as the adsorption belt conveyance device 102. That is, the belt conveyance unit 252 includes an endless conveyance belt 260, a driving roller 262, a driven roller 264, and a suction chamber 266. The paper P conveyed by the belt conveyance unit 252 is sent to the stacking device 62.

As shown in FIG. 21, a form in which the chain gripper 70 is not used as the transport mechanism of the paper P in the drying device 230 is also possible.

21 has a configuration in which the sensor 104 on the inlet side of the heat drying processing unit 90 is omitted, and the sensor 106 is arranged at one location on the outlet side of the heat drying processing unit 90. Yes.

<Description of control system of inkjet printing apparatus>
FIG. 22 is a block diagram illustrating a schematic configuration of a control system of the inkjet printing apparatus 1A. The ink jet printing apparatus 1 A includes a system controller 300. The system controller 300 includes a CPU 300A, a ROM 300B, and a RAM 300C. CPU is an abbreviation for Central Processing Unit. ROM is an abbreviation for Read Only Memory. RAM is an abbreviation for Random Access Memory. Note that storage units such as the ROM 300B and the RAM 300C may be provided outside the system controller 300.

The system controller 300 functions as an overall control unit that comprehensively controls each unit of the inkjet printing apparatus 1A. The system controller 300 functions as a calculation unit that performs various calculation processes. Further, the system controller 300 functions as a memory controller that controls reading and writing of data in memories such as the ROM 300B and the RAM 300C.

The ink jet printing apparatus 1A includes a communication unit 302, an image memory 304, a conveyance control unit 310, a paper feed control unit 312, a processing liquid application control unit 314, a processing liquid drying control unit 316, a drawing control unit 318, an ink drying control unit 320, And a paper discharge control unit 324. These elements of each part can be realized by one or a plurality of computers. That is, each element of the control system including the system controller 300 can be configured by a combination of computer hardware and software. Further, some or all of the processing functions necessary for control may be realized by using an integrated circuit represented by a DSP (Digital Signal Processor) or FPGA (Field Programmable Gate Array).

The communication unit 302 includes a communication interface (not shown), and can exchange data with the host computer 400 connected to the communication interface.

The image memory 304 functions as a temporary storage unit for various data including image data. Image data captured from the host computer 400 via the communication unit 302 is temporarily stored in the image memory 304.

The conveyance control unit 310 controls the operation of the conveyance system 11 for the paper P in the inkjet printing apparatus 1A. The transport system 11 includes a paper transport mechanism such as the paper supply drum 16, the processing liquid coating drum 22, the processing liquid drying drum 32, and the drawing drum 42 illustrated in FIG. 1. Further, the transport system 11 includes a motor as a power source (not shown) and a driving unit such as a motor driving circuit.

The paper feed control unit 312 shown in FIG. 22 operates the paper feed unit 10 in response to a command from the system controller 300. The paper feed control unit 312 controls a paper P supply start operation, a paper P supply stop operation, and the like.

The processing liquid application control unit 314 operates the processing liquid application unit 20 in response to a command from the system controller 300. The processing liquid application control unit 314 controls the application amount of the processing liquid, the application timing, and the like.

The processing liquid drying control unit 316 operates the processing liquid drying unit 30 in response to a command from the system controller 300. The treatment liquid drying control unit 316 controls the drying temperature, the flow rate of the drying gas, the timing for spraying the drying gas, and the like.

The drawing control unit 318 controls the operation of the drawing unit 40 in response to a command from the system controller 300. The drawing control unit 318 includes an image processing unit, a waveform generation unit, a waveform storage unit, and a drive circuit. The illustration of the image processing unit, waveform generation unit, waveform storage unit, and drive circuit is omitted. The image processing unit forms dot data from the input image data. The waveform generator generates a drive voltage waveform. The waveform storage unit stores the waveform of the drive voltage. The drive circuit generates a drive voltage having a drive waveform corresponding to the dot data. The drive circuit supplies a drive voltage to the liquid discharge head.

In the image processing unit, color separation processing for separating input image data into RGB colors, color conversion processing for converting RGB into CMYK, correction processing such as gamma correction and unevenness correction, and gradation values for each color pixel. A halftone process for converting to a gradation value less than the original gradation value is performed.

As an example of input image data, raster data represented by a digital value from 0 to 255 can be cited. The dot data obtained as a result of the halftone process may be binary, or may be a multi-value that is three or more and less than the gradation value before the halftone process.

Based on the dot data generated through the processing by the image processing unit, the ejection timing and ink ejection amount at each pixel position are determined, the ejection timing at each pixel position, the drive voltage corresponding to the ink ejection amount, and the ejection of each pixel. A control signal for determining the timing is generated, this drive voltage is supplied to the liquid discharge head, and dots are recorded by the ink discharged from the liquid discharge head.

The drawing control unit 318 may include a correction processing unit (not shown). The correction processing unit executes a correction process for the abnormal nozzle. When the correction process is performed, a decrease in image quality due to the occurrence of abnormal nozzles is suppressed.

The ink drying control unit 320 operates the ink drying unit 50 in response to a command from the system controller 300. The ink drying control unit 320 controls the drying gas temperature, the flow rate of the drying gas, or the ejection timing of the drying gas. The combination of the system controller 300 and the ink drying control unit 320 corresponds to the control unit 212 described with reference to FIG.

The paper discharge control unit 324 operates the stacking unit 60 in response to a command from the system controller 300. When the stacking device 62 shown in FIG. 1 includes an elevating mechanism, the paper discharge control unit 324 controls the operation of the elevating mechanism according to the increase or decrease of the paper P.

The inkjet printing apparatus 1A shown in FIG. 22 includes an operation unit 330, a display unit 332, a parameter storage unit 334, and a program storage unit 336.

The operation unit 330 includes an input device including operation buttons, a keyboard, a mouse, a touch panel, or a combination thereof. The operation unit 330 may include a plurality of types of operation members. The illustration of the operation member is omitted.

Information input via the operation unit 330 is sent to the system controller 300. The system controller 300 executes various processes according to information sent from the operation unit 330.

The display unit 332 includes a display device (display) such as a liquid crystal panel. The display unit 332 can display various pieces of information such as various setting information of the apparatus or abnormality information in response to a command from the system controller 300. The operation unit 330 and the display unit 332 constitute a user interface. The user can set various parameters and input and edit various information using the operation unit 330 while viewing the contents displayed on the screen of the display unit 332.

The parameter storage unit 334 stores various parameters used in the inkjet printing apparatus 1A. Various parameters stored in the parameter storage unit 334 are read out via the system controller 300 and set in each unit of the apparatus.

The program storage unit 336 stores a program used for each unit of the inkjet printing apparatus 1A. Various programs stored in the program storage unit 336 are read out via the system controller 300 and executed in each unit of the apparatus.

22 is provided with a maintenance control unit 338. The inkjet printing apparatus 1A shown in FIG. The maintenance control unit 338 controls the operation of the maintenance unit 340 in accordance with a command from the system controller 300. The operation of the maintenance unit 340 includes an operation of applying a cleaning liquid to a web (not shown) and a wiping operation by the web. Further, the operation in the maintenance unit 340 may include a purge process of the inkjet head, preliminary ejection, and the like.

<Discharge method of inkjet head>
An ejector of an inkjet head includes a nozzle that discharges liquid, a pressure chamber that communicates with the nozzle, and a discharge energy generating element that applies discharge energy to the liquid in the pressure chamber. With respect to the ejection method for ejecting liquid droplets from the nozzle of the ejector, the means for generating the ejection energy is not limited to the piezoelectric element, and various ejection energy generating elements such as a heating element and an electrostatic actuator can be applied. For example, it is possible to employ a method in which droplets are ejected using the pressure of film boiling caused by heating of a liquid by a heating element. Corresponding ejection energy generating elements are provided in the flow path structure according to the ejection method of the inkjet head.

<< Specific examples of treatment liquid >>
The treatment liquid may be referred to as a pretreatment liquid, an undercoat liquid, or a precoat liquid. The treatment liquid contains at least an aggregating agent for aggregating the components in the ink composition of the color ink, and can be constituted using other components as necessary. By using the treatment liquid together with the ink composition, it is possible to increase the speed of ink jet recording, and an image excellent in reproducibility of high density and resolution, for example, fine lines and fine portions can be obtained even at high speed recording.

The flocculant may be a compound that can change the pH of the ink composition, a polyvalent metal salt, or a polyallylamine. In the embodiment described with reference to FIG. 1, from the viewpoint of the cohesiveness of the ink composition, a compound capable of changing the pH of the ink composition is preferable, and a compound capable of lowering the pH of the ink composition is more preferable.

As the flocculant used in the present embodiment, an acidic substance having high water solubility is preferable, and an organic acid is preferable from the viewpoint of increasing the aggregation property and fixing the whole ink, and a divalent or higher organic acid is more preferable. Above-mentioned trivalent or less acidic substances are particularly preferred. As the divalent or higher organic acid, an organic acid having a first pKa (acid dissociation constant) of 3.5 or less is preferable, and an organic acid of 3.0 or less is more preferable. Specific examples include phosphoric acid, oxalic acid, malonic acid, citric acid and the like. A flocculant can be used individually by 1 type or in mixture of 2 or more types.

The content of the flocculant for aggregating the ink composition in the treatment liquid is preferably 1 to 50% by mass, more preferably 3 to 45% by mass, and still more preferably 5 to 40% by mass.

The treatment liquid can further contain other additives as other components within a range not impairing the intended aggregation effect. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, anti-foaming agents. Well-known additives, such as a foaming agent, a viscosity modifier, a dispersing agent, a dispersion stabilizer, a rust preventive agent, a chelating agent, are mentioned.

<About paper>
“Paper” is a medium used for image formation. The term “paper” is a generic term for a variety of terms such as recording paper, printing paper, printing medium, printing medium, printing medium, image forming medium, image forming medium, image receiving medium, and discharged medium. The material, shape, and the like of the paper are not particularly limited, and various sheet bodies can be used regardless of sealing paper, resin sheet, film, cloth, nonwoven fabric, and other materials and shapes. The paper recording is not limited to a sheet medium, but may be a continuous medium such as continuous paper. Further, the sheet of paper is not limited to a cut sheet that has been preliminarily adjusted to a predetermined size, and may be obtained by cutting from a continuous medium to a predetermined size as needed.

<< Advantages of the Embodiment >>
(1) According to the drying

apparatuses

100 and 230 described as the first embodiment and the second embodiment, the paper P on which an image is formed is sucked and transported by the suction belt transport method, and the paper P is heated and dried. Since the process is performed, the cockle can be effectively suppressed.

(2) Also, the drying

devices

100 and 230 detect the feed rate of the conveyor belt 110 and the amount of change in the position in the width direction by the same sensor 104 (and / or sensor 106), and thus a sensor for detecting the feed rate. Compared with a configuration in which sensors for detecting the position in the width direction are separately provided, it is possible to acquire information on the feed rate and information on the position in the width direction with a small number of sensors.

(3) According to the drying

apparatuses

100 and 230, the fluctuation amount of the position in the width direction of the conveyor belt 110 is monitored, and when a fluctuation exceeding a specified allowable range is detected, the belt tension is controlled to convey the belt. The meandering of the belt 110 can be improved. Thereby, stable paper conveyance is possible.

<< Modification 1 >>
The shape of the mark provided on the conveyance belt 110 is not limited to one type, and a plurality of types of marks may be used in combination. For example, the mark for detecting the feed speed and the mark for detecting the position in the width direction may be formed in different shapes.

<< Modification 2 >>
In the mark set, marks of different shapes such as triangular marks and circular marks may be used in combination. The mark or the mark set can adopt various forms as long as the object of detecting the change in the feed speed and the change in the position in the width direction can be achieved.

The mark preferably has a polygonal shape including a line segment in an oblique direction that is not parallel to the transport direction and not parallel to the width direction as a boundary line, or a plan view shape of a closed curve including a curve as a boundary line.

<< Modification 3 >>
In the above-described embodiment, the single-pass inkjet printing apparatus has been described as an example of the image forming apparatus. However, the present invention can be applied to various forms of image forming apparatuses. For example, the present invention can be applied to a plateless type printing machine such as a multi-scan type inkjet printing apparatus or an offset printing machine that forms an image by reciprocating a short inkjet head.

<< Modification 4 >>
The method for adsorbing the sheet to the conveyance belt is not limited to the suction adsorption by the negative pressure, and other methods such as electrostatic adsorption may be used.

<< Modification 5 >>
The drying apparatus according to the present invention is not limited to an aspect used as a mechanism for drying ink, but can also be used as a mechanism for drying liquid other than ink. Specific examples of attaching a liquid other than ink to the paper include a treatment liquid and a varnish. Also for liquids such as treatment liquid and varnish, the wavy deformation of the paper due to drying can occur. In particular, the treatment liquid using water and / or a solvent soluble in water, or a water-based varnish may have a problem of wavy deformation of the paper as in the case of the water-based ink.

Instead of the drying mechanism of the treatment liquid drying unit 30 described in FIG. 1, the same configuration as the drying device 100 described in FIG. 2 or the same configuration as the drying device 230 described in FIG.

<< Modification 6 >>
For the purpose of protecting the printed surface or imparting gloss, varnish printing may be performed on a part of or the entire printed surface. Varnish printing is sometimes called varnish coat or overcoat. The drying apparatus according to the present invention can be used as a mechanism for drying the paper after varnish printing.

《Terminology》
The term “printing apparatus” is synonymous with terms such as a printing press, a printer, a printing apparatus, an image recording apparatus, an image forming apparatus, an image output apparatus, or a drawing apparatus.

“Image” is to be interpreted in a broad sense and includes color images, black and white images, single color images, gradation images, uniform density (solid) images, and the like. The “image” is not limited to a photographic image, but is used as a comprehensive term including a pattern, a character, a symbol, a line drawing, a mosaic pattern, a color painting pattern, other various patterns, or an appropriate combination thereof.

In addition, the “image” is not limited to an image formed with ink containing a color material, and is formed with a treatment liquid applied to the paper before applying ink and / or a varnish applied to the paper after applying ink. It may be an image. For example, an aspect in which the treatment liquid is solidly applied to the paper and / or an aspect in which the aqueous varnish is solidly applied to the paper are also included in the concept of forming an image. A sheet with a solid treatment liquid and / or a sheet with a solid varnish corresponds to one form of “sheet on which an image is formed”. The drying device of the present invention can be applied as a drying device for drying the paper to which the treatment liquid has been applied. Further, the drying device of the present invention can be applied as a drying device for drying the paper to which the varnish is applied.

“Image formation” includes the concept of terms such as image recording, printing, printing, drawing, and printing.

“The expression“ dry the paper ”includes the same meaning as drying the ink adhered to the paper. Further, the expression “dry the paper” includes the same meaning as drying the treatment liquid and / or varnish attached to the paper.

In the present specification, the term “orthogonal” or “perpendicular” refers to a case of intersecting at an angle of substantially 90 ° in an aspect of intersecting at an angle of less than 90 ° or greater than 90 °. The mode which produces the same operation effect as is included.

<< Combination of Embodiments and Modifications >>
The matters described in the above-described embodiments and the modifications can be used in appropriate combinations, and some of the matters can be replaced.

In the embodiment of the present invention described above, the configuration requirements can be changed, added, or deleted as appropriate without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the related fields within the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1A Inkjet printer 10 Paper feeder 11 Conveying system 12 Paper feeder 12A Paper feeder 14 Feeder board 16 Paper drum 20 Treatment liquid application part 22 Treatment liquid application drum 23 Gripper 24 Treatment liquid application apparatus 30 Treatment liquid drying part 32 Liquid drying drum 33 Gripper 34 Warm air blower 40 Drawing unit 42 Drawing drum 43 Gripper 44 Head unit 46C Inkjet head 46K Inkjet head 46M Inkjet head 46Y Inkjet head 48 Image reading device 50 Ink drying unit 60 Stacking unit 62 Stacking device 62A Stacking tray 70 Chain gripper 71A First sprocket 71B Second sprocket 72 Chain 74 Gripper 80 Paper guide 82 First paper guide 84 Second paper guide 90 Heating and drying processing unit 100 Drying device 102 G transport device 104, 106 sensor 110 transport belt 112 drive roller 114 driven roller 116 suction chamber 116A first chamber 116B second chamber 116C third chamber 120 suction hole 130 infrared heater 132 air blower 134 air chamber 136 air blow nozzle 142 first oil Flow path 144 Second oil flow path 152 First guide roller 154 Second guide roller 160 Mark 162 Paper suction area 164 Sensing point peripheral area 166 Sensing point peripheral area 170 Paper suction areas 170A, 170B, 170C Paper suction area 180 Mark 182 Mark set 204 Sensing point 206 Sensing point 210 Signal processing unit 212 Control unit 214 Drive motor 220 Tension difference adjusting mechanism 221 First tension applying mechanism 222 Second tension applying mechanism 230 Drying device 240 Transfer drum 242 Gripper 252 Belt conveyor 260 Transport belt 262 Drive roller 264 Driven roller 266 Suction chamber 300 System controller 300A CPU
300B ROM
300C RAM
302 Communication unit 304 Image memory 310 Transport control unit 312 Paper feed control unit 314 Processing liquid application control unit 316 Processing liquid drying control unit 318 Drawing control unit 320 Ink drying control unit 324 Paper discharge control unit 330 Operation unit 332 Display unit 334 Parameter storage Unit 336 program storage unit 338 maintenance control unit 340 maintenance unit 400 host computer

Claims

A transport belt for transporting the paper in a state in which at least a part of the paper on which an image is formed is adsorbed;
A heat-drying processing unit for applying heat to the paper being sucked and transported by the transport belt to dry the paper;
A sensor for detecting a feed rate in the transport direction of the transport belt and a fluctuation amount of a position in the width direction orthogonal to the transport direction of the transport belt;
A drying apparatus comprising:
The drying apparatus according to claim 1, wherein the sensor is a non-contact type sensor.
The drying apparatus according to claim 2, wherein the sensor is an optical sensor that uses reflected light from the transport belt or transmitted light that has passed through the transport belt.
The drying apparatus according to claim 3, wherein the conveyor belt has a mark for changing an intensity of light received by the sensor.
The mark is a reflective mark that reflects light,
The drying apparatus according to claim 4, wherein the transport belt has at least one reflection mark.
The mark is a light passage hole that allows light to pass through,
The drying apparatus according to claim 4, wherein the transport belt has at least one light passage hole.
The conveyor belt has at least one mark set formed by arranging a plurality of the marks in a two-dimensional array pattern,
The drying apparatus according to any one of claims 4 to 6, wherein the mark set region has a shape that changes in each of the transport direction and the width direction.
The said mark has the planar view shape of the polygon which includes the line segment of the diagonal direction which is not parallel to the said conveyance direction and is not parallel to the said width direction in a boundary line, or the closed curve which includes a curve in a boundary line. The drying apparatus as described in any one of 7 to 7.
9. The transport belt according to claim 4, wherein the transport belt has a belt length capable of sucking and transporting a plurality of sheets of paper at the same time, and has the mark for each paper suction region for sucking the plurality of sheets of paper. The drying apparatus according to item.
The drying device according to any one of claims 1 to 9, wherein a plurality of the sensors are arranged in the transport direction.
A signal processing unit for processing a signal obtained from the sensor, which performs a process of detecting a change in a feeding speed in the transport direction from an interval of signals obtained from the sensor, and the number of signals obtained from the sensor The drying apparatus according to claim 1, further comprising: a signal processing unit that performs a process of detecting a fluctuation amount of the position in the width direction from at least one of the signal duration time.
A driving roller and a driven roller,
The drying apparatus according to any one of claims 1 to 11, wherein the conveyor belt is an endless belt wound around the driving roller and the driven roller.
A tension difference adjusting mechanism for adjusting the belt tension difference in the width direction;
A control unit for controlling the tension difference adjusting mechanism based on a variation amount of the position in the width direction detected using the sensor;
The drying apparatus according to claim 12.
The transport belt is provided with a plurality of suction holes,
A suction chamber is disposed on the opposite side of the conveying belt from the paper support surface,
The drying apparatus according to claim 1, wherein the sheet is adsorbed to the transport belt by air pressure through the suction hole.
A gripper for gripping the leading end of the paper;
A gripper transport unit for transporting the paper gripped by the gripper;
With
The drying apparatus according to any one of claims 1 to 14, wherein the sheet is conveyed in a state where a part of the sheet conveyed by the gripper conveyance unit is adsorbed to the conveyance belt.
An image forming unit that forms an image on paper using ink;
A drying apparatus according to any one of claims 1 to 15,
With
An image forming apparatus for drying the paper on which an image has been formed by the image forming unit by the drying device.
The image forming unit includes:
An inkjet head for discharging aqueous ink;
A drawing drum disposed opposite to the inkjet head and conveying paper to the inkjet head,
The image forming apparatus according to claim 16, wherein the conveyance belt is driven at a feeding speed synchronized with the rotation of the drawing drum.