JP2023062855A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that performs curl correction of a sheet, before forming an image on the sheet.SOLUTION: A sheet S is conveyed with a conveyance passage 20. A sensor 14 working on the conveyed sheet S detects a curl amount in a conveyance direction of the sheet S to output curl amount information. An ink jet head 32 forms an image on the sheet S. A conveyance belt 31 arranged on a conveyance direction downstream side of the sensor 14 feeds the sheet S to the ink jet head 32. A storage unit 4 stores a change pattern of the curl amount. A detection unit 5 detects the change pattern of the curl amount of the sheet S, based on the curl amount information and the change pattern of the curl amount stored by the storage unit 4. A curl correction unit 33 arranged near the conveyance belt 31 corrects curl of the sheet S. A control unit 6 controls the curl correction unit 33, based on the change pattern of the curl amount of the sheet S.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus.

Japanese Unexamined Patent Application Publication No. 2004-200002 discloses an inkjet printing apparatus capable of accurately detecting curling of a printing medium.

JP 2019-130789 A

However, Japanese Patent Application Laid-Open No. 2002-200001 does not correct curl before forming an image on the sheet.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus that corrects the curl of a sheet before forming an image on the sheet.

An image forming apparatus according to the present invention includes a transport path, a sensor, an inkjet head, a transport belt, a storage section, a detection section, a curl correction section, and a control section. A sheet is conveyed through the conveying path. The sensor works on the sheet being conveyed, detects the curl amount of the sheet in the conveying direction, and outputs curl amount information. The inkjet head forms an image on the sheet. The conveying belt is arranged downstream of the sensor in the conveying direction, and supplies the sheet to the ink head. The storage unit stores the change pattern of the curl amount. The detection unit detects a variation pattern of the curl amount of the sheet S based on the curl amount information and the variation pattern. The curl correction unit is arranged near the conveying belt and corrects the curl of the sheet. The control unit controls the curl correction unit based on a variation pattern of the amount of curl of the sheet.

According to the image forming apparatus of the present invention, it is possible to correct the curl of the sheet before forming an image on the sheet.

1 is a diagram showing an image forming apparatus (inkjet printer) according to an embodiment of the present invention; FIG. 1 is a diagram showing an image forming apparatus (multifunction machine) according to an embodiment of the present invention; FIG. 2 is a diagram showing an image forming section of the image forming apparatus according to the embodiment; FIG. (a) and (b) are diagrams for explaining curl amount detection of the image forming apparatus according to the present embodiment. It is a figure which shows the change of curl amount. (a) and (b) are diagrams for explaining curl amount detection of the image forming apparatus according to the present embodiment. It is a figure which shows the change of curl amount. 4 is a flow chart showing processing of the image forming apparatus according to the embodiment of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. In addition, in the present embodiment, X-, Y-, and Z-axes that are orthogonal to each other are shown in the drawing. The Z axis is parallel to the vertical plane and the X and Y axes are parallel to the horizontal plane.

In this embodiment, the X-axis direction may be described as the main scanning direction. The Y-axis direction may be described as a sub-scanning direction. The Z-axis direction is sometimes described as a direction intersecting the main scanning direction and the sub-scanning direction.

An image forming apparatus 3 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. FIG. 1 is a diagram showing an image forming apparatus 3 (inkjet printer 3) according to an embodiment of the present invention. FIG. 2 is a diagram showing an electrophotographic image forming apparatus 3 (complex machine 1) according to an embodiment of the present invention.

FIG. 3 is a diagram showing the image forming section 15 of the image forming apparatus 3 according to this embodiment. FIGS. 4A and 4B are diagrams for explaining curl amount detection of the image forming apparatus 3 according to the present embodiment. FIG. 5 is a diagram showing changes in curl amount. FIGS. 6A and 6B are diagrams for explaining curl amount detection of the image forming apparatus 3 according to the present embodiment. FIG. 7 is a diagram showing changes in the amount of curl.

A configuration common to the inkjet printer 3 and the image forming apparatus 3 of the multifunction machine 1 will be described below with reference to FIGS. 1 and 2. FIG. A configuration unique to the inkjet printer 3 will be described with reference to FIG. A configuration unique to the multifunction machine 1 will be described with reference to FIG. When describing a configuration common to the inkjet printer 3 and the electrophotographic image forming apparatus 3, it is described as the image forming apparatus 3. FIG.

First, the inkjet printer 3 shown in FIG. 1 forms an ink image on the sheet S using a single color ink or a combination of multiple color inks. The multifunction machine 1 shown in FIG. 2 is, for example, an MFP (Multi Function Printer) that combines functions such as a scanner, a copier, a printer, a copier, and a facsimile. The multifunction machine 1 is, for example, a copier, a facsimile machine, or a multifunction machine having these functions.

As shown in FIG. 2 , the multifunction machine 1 includes a document reading device 2 . The document reading device 2 has, for example, a document feeding device 10 and an image reading device 11 . The document feeder 10 has, for example, a document tray, a document feeder, a document sensor, and a document discharge section. An example of the document feeder 10 is an ADF (Auto Document Feeder).

The image reading device 11 has an optical system. The optical system has, for example, a light emitting section, a lens, a reflecting mirror, and a light receiving section.

The image reading device 11 reads an image from a document G conveyed by the document feeding device 10 . The image reading device 11 generates image data from the read image. An example of the image reading device 11 is a CIS (Contact Image Sensor) or CCD (Charge Coupled Devices) scanner.

Next, as shown in FIGS. 1 and 2, the image forming apparatus 3 includes a feeding device 12, a conveying device 13, a sensor 14, an image forming section 15, an ejecting device 17, a storage section 4, A detection unit 5 and a control unit 6 are provided. The electrophotographic image forming apparatus 3 further includes a fixing device 16 .

The feeding device 12 feeds the sheet S. As shown in FIG. The feeding device 12 has, for example, a sheet tray and a pickup roller. A sheet S is placed on the sheet tray. The pickup roller picks up and feeds the sheet S placed on the sheet tray.

The conveying device 13 conveys the sheet S fed from the feeding device 12 . The transport device 13 has a transport path 20 and transport rollers 21 . The sheet S is conveyed along the conveying path 20 . The transport roller 21 transports the sheet S within the transport path 20 .

As shown in FIGS. 1 to 3, the sensor 14 works on the sheet S being conveyed, detects the amount of curl of the sheet S in the conveying direction, and outputs curl amount information.

Sensor 14 may be an ultrasonic sensor. The ultrasonic sensor irradiates the sheet S with ultrasonic waves and detects the volume of the reflected waves reflected on the sheet S. The ultrasonic sensor has an ultrasonic transmitter and an ultrasonic receiver.

That is, the ultrasonic wave transmission unit irradiates (transmits) the sheet S with ultrasonic waves. The ultrasonic wave receiving unit detects (receives) the volume of the reflected wave reflected by the sheet S. FIG. An example of an ultrasonic sensor is an electrostrictive transducer made of lead zirconate titanate.

According to this embodiment, the curl amount of the sheet S in the conveying direction can be preferably detected by using the ultrasonic sensor.

Sensor 14 may be a light intensity sensor. The light amount sensor irradiates the sheet S with light and detects the amount of reflected light reflected on the sheet S. FIG. The sensor 14 has a light emitting portion and a light receiving portion.

That is, the light emitting unit irradiates (emits light) the sheet S with light. The light receiving unit detects (receives) the amount of light reflected by the sheet S. FIG. An example of the light emitting unit is an LED (Light Emitting Diode). An example of the light receiving unit is a CCD (Charge Coupled Device).

According to this embodiment, the amount of curl of the sheet S in the conveying direction can be preferably detected by using the light amount sensor.

The image forming section 15 of the inkjet printer 3 has an ink tank 30 , a conveying belt 31 , an inkjet head 32 , and a curl correction section 33 .

The ink tank 30 is a tank that stores a single color or multiple colors of ink. The ink tank 30 is, for example, a cartridge filled with cyan, magenta, yellow, and black inks.

The conveying belt 31 supplies the sheet S conveyed by the conveying device 13 to the inkjet head 32 . The transport belt 31 is arranged downstream of the sensor 14 in the transport direction, and supplies the sheet S to the inkjet head 32 .

As shown in FIG. 3, the inkjet head 32 forms an ink image on the sheet S supplied by the conveying belt 31 . The inkjet head 32 is connected to the ink tank 30 . The inkjet head 32 is supplied with ink from the ink tank 30 .

The inkjet head 32 is arranged to face the conveyor belt 31 . A large number of nozzles are arranged in the inkjet head 32 . The inkjet head 32 forms an ink image on the sheet S by ejecting ink from nozzles.

As shown in FIG. 3, the curl correction unit 33 is arranged near the conveying belt 31 and corrects the curl of the sheet S. As shown in FIG. The sheet S may curl due to various reasons such as humidity. If the sheet S is curled and supplied to the inkjet head 32, the distance between the inkjet head 32 and the sheet S may become uneven, resulting in unstable image quality. Therefore, it is preferable to correct the curl before the ink image is formed by the inkjet head 32 .

The curl correction section 33 may be an air suction section. The air suction unit is arranged near the conveying belt 31 and sucks the sheet S onto the conveying belt 31 . The curl of the sheet S is corrected by the sheet S being sucked by the conveying belt 31 .

Specifically, the air suction unit may be arranged inside the conveying belt 31 . As shown in FIG. 3, the conveyor belt 31 may be provided with air intake holes. An example of an air sucker is a fan. When the fan generates suction, the suction holes generate suction, and the sheet S is attracted to the conveying belt 31 . Thereby, the curl of the sheet S is corrected.

The curl correction section 33 may be an air blowing section. The air blowing unit is arranged near the conveying belt 31 and blows air in a direction to press the sheet S against the conveying belt 31 . By blowing air onto the sheet S, the sheet S is attached to the conveying belt 31 and the curl of the sheet S is corrected.

Specifically, the air blowing section may be arranged outside the conveying belt 31 . An example of an air blower is a fan. When the fan blows air onto the sheet S, the sheet S is attached to the conveying belt 31 . Thereby, the curl of the sheet S is corrected.

The curl correction unit 33 may be a decurling roller. The decurling roller straightens the sheet S in a direction opposite to the curling direction. The decal rollers may be a pair of rollers. A decal roller presses from one roller to the other. One roller presses the other roller in a direction opposite to the curling direction of the sheet S, so that the curl of the sheet S that has passed through the nip of the decurling rollers is corrected.

According to this embodiment, the image quality of the ink image formed on the sheet S is stabilized by correcting the curl of the sheet S.

In the case of the electrophotographic image forming apparatus 3 , it includes an image forming section 15 and a fixing section 16 .

The image forming section 15 has, for example, an image data input section (not shown), a charging section, an exposure section, a developing section, a transfer section, and a cleaning section.

The fixing device 16 heats and presses the toner image developed on the sheet S to fix the toner image on the sheet S. As shown in FIG. The fixing device 16 has, for example, a fixing belt, a pressure roller, and a heater.

The fixing belt is a hollow cylindrical belt. The pressure roller is pressed against the fixing belt to form a nip with the fixing belt. The pressure roller is rotationally driven by a drive unit (not shown), and forms a nip portion with the fixing belt to rotate the fixing belt.

The heater is supplied with power from a power source (not shown) to heat the fixing belt. The heater is arranged close to the inner peripheral surface of the fixing belt. The sheet S conveyed to the sheet conveying device passes through the nip portion, is heated by the heater, and the toner image is fixed.

Next, as shown in FIGS. 1 and 2 , the discharge device 17 discharges the sheet S to the outside of the housing of the image forming apparatus 3 . The ejection device 17 may have an ejection roller and an ejection tray. The discharge roller discharges the image-formed sheet S to the discharge tray. The discharge tray stacks discharged sheets S thereon.

The storage unit 4 stores curl amount change patterns. The storage unit 4 includes a storage device and stores data and computer programs. Specifically, the storage unit 4 includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a semiconductor memory and/or a hard disk drive. The storage unit 4 may include removable media.

Specifically, as shown in FIG. 4A, when the sheet S is curled in the direction of the inkjet head 32, the graph of curl amount information detected by the sensor 14 has the shape shown in FIG. become. The storage unit 4 stores the relationship between the sheet length in the sub-scanning direction and the amount of light or volume as shown in FIG. 5 as a change pattern of the amount of curl. The storage unit 4 may store a plurality of similar curl amount change patterns.

Further, as shown in FIG. 6A, when the sheet S is curled in the direction of the conveying belt 31, the graph of the curl amount information detected by the sensor 14 has a shape shown in FIG. 7 as an example. The storage unit 4 stores the relationship between the sheet length in the sub-scanning direction and the amount of light or volume as shown in FIG. 7 as a change pattern of the amount of curl. The storage unit 4 may store a plurality of similar curl amount change patterns.

The detection unit 5 detects the curl amount change pattern of the sheet S based on the curl amount information and the curl amount change pattern stored in the storage unit 4 . The detection unit 5 acquires curl amount information of the sheet S as shown in FIG. 5 from the sensor 14 . The detecting unit 5 acquires a change pattern identical or similar to the curl amount information of the sheet S acquired from the sensor 14 from the curl amount change patterns stored in the storage unit 4 .

The detector 5 acquires curl amount information of the sheet S as shown in FIG. 7 from the sensor 14 . The detecting unit 5 acquires a change pattern identical or similar to the curl amount information of the sheet S acquired from the sensor 14 from the curl amount change patterns stored in the storage unit 4 .

The control unit 6 controls the curl correction unit 33 based on the change pattern of the curl amount of the sheet S. FIG.

According to the present embodiment, the curl of the sheet S can be corrected before the image is formed on the sheet S. FIG.

Further, the control unit 6 may change the electric power supplied to the curl correction unit 33 according to the change pattern of the amount of curl. Specifically, in the case of the change pattern shown in FIG. 5, the control section 6 controls the power section (not shown). The power section may supply the curl correcting section 33 with the highest power at the leading edge of the sheet S in the conveying direction. The power section may reduce the power supplied to the curl correction section 33 as the sheet S is conveyed.

In the case of the change pattern shown in FIG. 7, the control section 6 controls the power section (not shown). For example, the power unit may increase the power supplied to the curl correction unit 33 until the sheet S is transported by about 10 cm from the leading edge in the transport direction, and then reduce the power.

Further, the control section 6 may change the suction force of the air suction section according to the change pattern of the curl amount. Specific control of the suction force is omitted because it overlaps with the above.

Further, the control section 6 may change the blowing force of the air blowing section according to the change pattern of the curl amount. Specific control of the blowing force is omitted because it overlaps with the above.

Further, the control unit 6 may change the nip strength of the decurling roller according to the change pattern of the curl amount. Specific control of the blowing force is omitted because it overlaps with the above.

According to this embodiment, even when sheets S having different curl amounts or different stiffnesses are conveyed, the curl can be preferably corrected.

Next, processing by the image forming apparatus 3 according to this embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing processing of the image forming apparatus 3 according to this embodiment.

As shown in FIG. 8, the flowchart includes steps S10 to S16. Specifically, it is as follows.

As shown in FIG. 7, the conveying belt 31 feeds the sheet S in step 10 . The process proceeds to step S12.

In step S12, the sensor 14 detects the curl amount of the sheet S in the conveying direction and outputs curl amount information. The process proceeds to step S14.

In step S<b>14 , the detection unit 5 detects a change pattern of the curl amount of the sheet S. FIG. The process proceeds to step S16.

In step S<b>16 , the curl correction unit 33 corrects the curl of the sheet S based on the change pattern of the amount of curl of the sheet S. Then the process ends.

The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiments, and can be implemented in various aspects without departing from the gist of the present invention. In order to facilitate understanding, the drawings mainly show each component schematically, and the number of each component shown in the drawing differs from the actual number for the convenience of drawing. Also, each component shown in the above embodiment is an example and is not particularly limited, and various modifications are possible within a range that does not substantially deviate from the effects of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be used in the field of image forming apparatuses.

1 MFP 2 Document reader 3 Image forming device (inkjet printer)
4 storage unit 5 detection unit 6 control unit 14 sensor 15 image forming unit 31 conveying belt 32 inkjet head 33 curl correction unit

Claims (10)

a conveying path along which the sheet is conveyed;
a sensor that acts on the sheet being conveyed to detect the amount of curl in the conveying direction of the sheet and outputs curl amount information;
an inkjet head for forming an image on a sheet;
a conveying belt that is arranged downstream of the sensor in the conveying direction and that supplies the sheet to the inkjet head;
a storage unit that stores a curl amount change pattern;
a detection unit that detects a change pattern of the curl amount of the sheet based on the curl amount information and the change pattern of the curl amount stored in the storage unit;
a curl correction unit disposed in the vicinity of the conveying belt for correcting the curl of the sheet;
An image forming apparatus, comprising: a control unit that controls the curl correction unit based on a variation pattern of curl amount of a sheet. 2. The image forming apparatus according to claim 1, wherein the sensor is an ultrasonic sensor that irradiates the sheet with ultrasonic waves and detects the volume of reflected waves reflected from the sheet. 2. The image forming apparatus according to claim 1, wherein the sensor is a light amount sensor that irradiates the sheet with light and detects the amount of light reflected by the sheet. 4. The image forming apparatus according to claim 1, wherein the curl correcting section is an air suction section that is arranged near the conveying belt and sucks the sheet to the conveying belt. 4. The image according to any one of claims 1 to 3, wherein the curl correcting section is an air blowing section that is arranged near the conveying belt and blows air in a direction to press the sheet against the conveying belt. forming device. The image forming apparatus according to any one of claims 1 to 3, wherein the curl correction unit is a decurl roller that corrects the sheet in a direction opposite to the curl direction. The image forming apparatus according to any one of claims 1 to 6, wherein the control section changes power supplied to the curl correction section according to the change pattern of the curl amount. 5. The image forming apparatus according to claim 4, wherein the control section changes the suction force of the air suction section according to the change pattern of the curl amount. 6. The image forming apparatus according to claim 5, wherein the control section changes the blowing force of the air blowing section in accordance with the change pattern of the curl amount. 7. The image forming apparatus according to claim 6, wherein the controller changes the nip strength of the decurling roller according to the change pattern of the curl amount.

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