JP2007001171A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when recording a solid image by ejecting a recording liquid on a sheet heated by a heater, a cockling of the sheet is liable to occur, easy to deteriorate the image due to friction. <P>SOLUTION: When the humidity of the sheet 5 detected by a humidity sensor 141 is not less than a prescribed value, the image forming device determines whether the liquid ejection amount in printing data to be printed on the sheet 5 to be supplied is not less than a prescribed amount or not. When the liquid ejection amount in the printing data is less than the prescribed value, the sheet 5 stored in a sheet supply cassette 41 is heated and dried, while setting the heater 142 to an on-state for a prescribed period. Then, the operation is shifted to sheet feeding operation without heating the sheet 5 by setting the heater 142 to the on-state, when the liquid ejection amount is not less than the prescribed amount, even if the humidity is not less than the prescribed value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms an image by ejecting droplets of a recording liquid onto a recording medium.

  In general, as an image forming apparatus that combines a printer / fax / copier or a combination of these functions, an image forming unit that employs an electrophotographic method is known. For example, liquid discharge that discharges liquid droplets of recording liquid is known. Recording is performed while a recording medium (hereinafter also referred to as “paper” is not limited to a material, and the recording medium, a transfer material, and the like are also used synonymously) using a recording head constituted by a head. Some are equipped with an image forming unit of an ink jet system that performs image formation (recording, printing, printing, and printing are also used synonymously) by attaching liquid droplets (hereinafter also referred to as ink droplets) to paper. is there.

In such an ink jet recording apparatus, since it is necessary to improve the landing position accuracy of ink droplets on the paper in order to improve the image quality, the paper is transported as disclosed in Patent Documents 1 and 2, for example. The conveyor belt is charged uniformly and positively, and the paper is attracted by the electrostatic force to keep the distance between the recording head and the paper constant, and the paper feed is accurately controlled to prevent misalignment of the paper. It is also known to prevent jamming and dirt due to the contact between the paper and the recording head by preventing the paper from floating.
JP 2000-25249 A JP 2004-099280 A

Further, in contrast to the above-described method of uniformly and positively charging the conveyor belt, as disclosed in Patent Document 3, by applying a positive and negative alternating voltage to the conveyor belt, plus and minus are applied on the conveyor belt. There is one in which an electrostatic attraction force is generated by forming a negative charge pattern.
Japanese Patent Laid-Open No. 2004-131242

Others using a conveyor belt that generates an electrostatic force are described in Patent Document 4.
JP-A-6-219582

On the other hand, in the electrophotographic image forming apparatus, if the recording medium absorbs moisture, not only wrinkles, corner breaks, etc. occur, but the transportability is deteriorated, and fixing and transfer are insufficient. Therefore, as described in Patent Document 5, the humidity around the paper storage unit is provided with a humidity detection unit that detects the humidity around the paper storage unit and a dehumidification unit that removes moisture from the paper. In some cases, the paper is dehumidified by controlling the dehumidifying means based on the detection result and the detection result of the amount of paper stored in the paper storage unit.
JP 2000-255807 A

Similarly, there are image forming apparatuses as described in Patent Documents 6 and 7 as dehumidifiers by heating paper.
Japanese Patent Laid-Open No. 11-255361 JP 2002-148996 A

In addition, as described in Patent Document 8, as an image forming apparatus that performs control based on the ink discharge amount, it moves with a gap with respect to the printing unit that discharges ink droplets. An intermediate transfer body, a powder applying means for applying a powder composed of a set agent for increasing the viscosity of ink droplets discharged from the printing means onto the intermediate transfer body, and an ink discharged from the printing means Transfer means for transferring an ink image formed on the intermediate transfer body by droplets onto a recording medium, and applying the amount of powder applied onto the intermediate transfer body by the powder application means to the printing means Are controlled in accordance with the printing rate, which is the amount of ink discharged from the printer.
JP 2002-292852 A

  By the way, in an image forming apparatus that forms an image by ejecting droplets of a recording liquid onto a recording medium, cockling or curling such as undulation of the recording medium due to the droplets adhering to the recording medium occurs. As a result, the recording medium rubs against the recording head and the image quality deteriorates. For this reason, the amount of curl after printing can be kept low when the recording medium is dried (humidity is low), and the recording medium is dried (humidity is low). Separation from the conveyor belt is also improved.

  Therefore, when the humidity of the recording medium is detected and the recording medium is high as in the conventional image forming apparatus described above, the recording medium is heated and dried by the heating means (or dehumidifying means) ( By setting the humidity to a low level, curling of the recording medium can be suppressed.

  However, when a large amount of liquid droplets are ejected and adhered to a recording medium that has been heated by a heating means and has a low humidity (dried), the humidity change of the recording medium suddenly decreases. There are problems that cockling occurs in the recording medium and the image quality deteriorates due to rubbing against the recording head, or that jamming occurs.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that improves the transportability of a recording medium while preventing deterioration in image quality.

  In order to solve the above-described problem, an image forming apparatus according to the present invention is accommodated in a storage unit that stores a recording medium, a heating unit that heats the recording medium stored in the storage unit, and a storage unit. A control unit for controlling the heating unit based on the detection result of the humidity of the recording medium and information correlating with the ejection amount of the droplets for forming an image on the recording medium is provided.

  Here, it is preferable not to heat the recording medium by the heating means regardless of the detection result of the humidity detecting means when the discharge amount of the droplets for forming an image on the recording medium exceeds a predetermined amount. Further, it is preferable that the recording medium is attracted and conveyed by an electrostatic force generated by applying an electric charge on the conveying belt. In this case, when the humidity detected by the humidity detecting means is less than a predetermined value, the application of electric charges to the conveyor belt is controlled based on the detected humidity, and when the detected humidity is equal to or higher than the predetermined value, the recording medium is heated by the heating means. preferable.

  Further, it is preferable that the heating means is disposed above the recording medium accommodated in the accommodating means. Furthermore, it is preferable to provide an externally operable switch means for opening and closing the power supply path to the heating means. It is preferable that a document reading unit for reading a document is provided.

  According to the image forming apparatus of the present invention, heating is performed based on the detection result of the humidity of the recording medium accommodated in the accommodating means and information correlating with the droplet discharge amount for forming an image on the recording medium. Since the recording medium is controlled, the recording medium can be prevented from being heated when the amount of droplet discharge is large even when the humidity of the recording medium is high, thereby causing cockling or the like in the recording medium. As a result, it is possible to improve the transportability of the recording medium while preventing deterioration of the image quality, such as rubbing with the head.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention will be described with reference to FIGS. 1 is a schematic configuration diagram showing the overall configuration of the image forming apparatus, FIG. 2 is an explanatory plan view of an image forming unit and a sub-scanning conveying unit of the apparatus, and FIG. 3 is an enlarged explanatory diagram of the sub-scanning conveying unit. is there.

  This image forming apparatus has an image forming part (means) 2 for forming an image, a sub-scanning conveying part (means) 3, etc. in the inside (enclosure) of the apparatus main body 1. A recording medium (hereinafter referred to as “paper”, but the material is not limited to paper) 5 serving as a transported member is separated and fed one by one from a paper feeding unit (means) 4 serving as a housing unit. Paper is formed and the sub-scanning conveyance unit 3 intermittently conveys the paper 5 at a position facing the image forming unit 2 while the image forming unit 2 ejects droplets onto the paper 5 to form (record) a desired image. After that, the paper 5 is discharged onto a paper discharge tray 7 formed on the upper surface of the apparatus main body 1 through the paper discharge conveyance unit 6.

  The image forming apparatus also has an image reading unit (scanner) for reading an image above the discharge tray 7 above the apparatus main body 1 as an input system for image data (print data) formed by the image forming unit 2. Part) 11. The image reading unit 11 includes a scanning optical system 15 including an illumination light source 13 and a mirror 14 and a scanning optical system 18 including mirrors 16 and 17. The scanned document image is read as an image signal by the image reading element 20 disposed behind the lens 19, and the read image signal is digitized and subjected to image processing, and the image-processed print data is printed. be able to. A pressure plate 10 is provided on the contact glass 12 for pressing the document.

  Further, this image forming apparatus uses an information processing apparatus such as an external personal computer, an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera as an input system for image data (print data) formed by the image forming unit 2. For example, print data including image data from the host side can be received via a cable or a network, and the received print data can be processed and printed.

  Here, as shown in FIG. 2, the image forming unit 2 of the image forming apparatus holds the carriage 23 movably in the main scanning direction by a carriage guide 21 and a guide stay (not shown), and is driven by a main scanning motor 27. It moves and scans in the main scanning direction via a timing belt 29 spanned between the pulley 28a and the driven pulley 28b.

  A recording head 24 including a droplet discharge head for discharging droplets of each color is mounted on the carriage 23, the carriage 23 is moved in the main scanning direction, and the sheet 5 is transferred to the sheet by the sub-scanning conveyance unit 3. A shuttle type is used in which droplets are ejected from the recording head 24 while feeding in the transport direction (sub-scanning direction) to form an image.

  The recording head 24 has two droplet discharge heads 24k1 and 24k2 that discharge black (Bk) ink, respectively, and one each that discharges cyan (C) ink, magenta (M) ink, and yellow (Y) ink. A total of five liquid droplet ejection heads (hereinafter simply referred to as “heads”), ie, liquid droplet ejection heads 24 c, 24 m, and 24 y, and each color ink is supplied from each sub tank 25 mounted on the carriage 23.

  On the other hand, as shown in FIG. 1, recording liquid containing black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink from the front of the apparatus main body 1 to the cartridge mounting portion 26A. Each color ink cartridge 26 can be detachably mounted as a cartridge, and ink is supplied from each color ink cartridge 26 to each color sub-tank 25. The black ink is supplied from one ink cartridge 26 to the two sub tanks 25.

  The recording head 24 uses a piezoelectric element as a pressure generating means (actuator means) for pressurizing the ink in the ink flow path (pressure generation chamber) to deform the vibration plate that forms the wall surface of the ink flow path. A so-called piezo type that discharges ink droplets by changing the volume in the flow channel, or discharges ink droplets with a pressure generated by heating the ink in the ink flow channel using a heating resistor to generate bubbles. The so-called thermal type, the diaphragm that forms the wall surface of the ink flow path and the electrode are placed opposite to each other, and the diaphragm is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby the ink flow path inner volume It is possible to use an electrostatic type or the like that discharges ink droplets by changing the above.

  A maintenance / recovery device 121 including a head cleaning device for maintaining and recovering the state of the nozzles of the recording head 24 is disposed in a non-printing area on one side of the carriage 23 in the scanning direction. The maintenance / recovery device 121 includes five moisturizing caps 122k2, 122k1, 122c, 122m, and 122y for capping the nozzle surfaces of the five recording heads 24 (“moisturizing caps” when colors are not distinguished). 122 ”), a single suction cap 123, a wiper blade 124 for wiping the nozzle surface of the recording head 24, an idle discharge receptacle 125 for performing idle discharge, and the like.

  The sub-scanning conveyance unit 3 includes a conveyance roller 32 and a tension roller that are driving rollers for conveying the paper 5 fed from below by facing the image forming unit 2 by changing the conveyance direction by approximately 90 degrees. An endless transport belt 31 spanned between the driven rollers 33, a charging roller 34 which is a charging means to which a high voltage as an alternating voltage is applied from a high voltage power source to charge the surface of the transport belt 31, and a transport A guide member 35 that guides the belt 31 in a region opposite to the image forming unit 2, a pressing roller (pressure roller) 36 that presses the paper 5 against the conveying belt 31 at a position facing the conveying roller 32, and the image forming unit 2. A separation claw 37 for separating the sheet 5 on which the image is formed from the conveyance belt 31 and a conveyance roller 38 for sending the separated sheet 5 to the paper discharge conveyance unit 6 are provided.

  The transport belt 31 of the sub-scan transport unit 3 is rotated in the paper transport direction (sub-scan direction) in FIG. 2 by rotating the transport roller 32 from the sub-scan motor 131 through the timing belt 132 and the timing roller 133. It is configured to do. As shown in FIG. 4, the transport belt 31 is made of, for example, a surface layer 31a that is a sheet adsorbing surface formed of a pure resin material that is not subjected to resistance control, for example, ETFE pure material, and the same material as the surface layer 31a. It has a two-layer structure with a back layer (medium resistance layer, earth layer) 31b subjected to resistance control with carbon.

  In addition, a cleaning unit (mylar is used here) 135 for removing paper dust and the like adhering to the surface of the conveyor belt 31 between the driven roller 33 and the charging roller 34, and the surface of the conveyor belt 31. And a static elimination brush 136 for removing electric charges.

  The paper feeding unit 4 is detachable from the apparatus main body 1 and separates the paper 5 in the paper feeding cassette 41 one by one from the paper feeding cassette 41 which is a storing means for stacking and storing a large number of papers 5. A sheet feeding roller 42 and a friction pad 43 for feeding out, and a sheet feeding conveyance roller 44 that conveys the fed sheet 5 to the sub-scanning conveyance unit 3 are provided. The paper feed roller 42 is rotated by a paper feed motor (drive source) 45 formed of an HB type stepping motor via a paper feed clutch (not shown), and the paper feed transport roller 44 is also rotationally driven by the paper feed motor 45.

  As shown in FIG. 5, the sheet feeding unit 4 includes a humidity sensor 141 that is a humidity detecting unit for detecting the humidity of the sheet 5 stored in the sheet feeding cassette 41 that is a storing unit. It is attached to the sheet metal member 1A and the like and arranged above the paper feed cassette 41. Further, a heater 142 which is a heating means for drying the paper 5 accommodated in the paper feed cassette 41 by heating is disposed above the paper feed cassette 41. That is, by arranging the heater 142 above the paper feed cassette 41, the uppermost paper 5 housed in the paper feed cassette 41 and fed can be heated most, and the bottom of the paper feed cassette 41 is The paper 5 to be fed can be heated more efficiently than when a heater is provided.

The paper discharge conveyance unit 6 includes a pair of paper discharge conveyance rollers 61 and 62 for conveying the paper 5 on which image formation has been performed, a paper discharge conveyance roller pair 63 and a paper discharge roller 64 for sending the paper 5 to the paper discharge tray 7. And.

Next, an outline of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
The control unit 300 includes a CPU 301 that controls the entire apparatus, a ROM 302 that stores programs executed by the CPU 301 and other fixed data, a RAM 303 that temporarily stores image data, and the like, while the apparatus is powered off. 1 includes a non-volatile memory (NVRAM) 304 for holding data, an image processing for performing various signal processing and rearrangement on image data, and an ASIC 305 for processing input / output signals for controlling the entire apparatus. Yes.

  The control unit 300 also includes an I / F 307 for transmitting / receiving data and signals to / from the host side, a head drive control unit 308 and a head driver 309 for driving and controlling the recording head 24, and the main scanning motor 27. A main scanning motor driving unit 311 for driving the sub scanning motor 131, a sub scanning motor driving unit 312 for driving the sub scanning motor 131, a paper feeding motor driving unit 313 for driving the paper feeding motor 141, and the charging roller 34. An AC bias supply unit 316 that applies an alternating voltage (here, a rectangular wave) that is a high voltage for charging the conveyor belt 31, and other clutches such as motors of an ink supply system and a paper feed clutch (not shown) It has a part that drives the kind.

  Further, as shown in FIG. 3, the control unit 300 includes a printing start sensor 201 that detects the sheet 5 that has passed through the conveying roller 32 and the pressing roller 36 on the upstream side of the recording head 24, and the downstream side of the conveying roller 38. The print end sensor 202 for detecting the paper 5, the home position sensor (not shown) of the maintenance / recovery device 121, the sensor for detecting the cover open of the device, and the humidity of the paper 5 accommodated in the paper feed cassette 41 described above are detected. An I / O 317 for inputting detection signals from various sensors such as a detection signal from the humidity sensor 141 is provided, and an operation panel 318 for inputting and displaying information necessary for this apparatus is connected.

  The control unit 300 receives print data and the like from the host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, and an imaging device such as a digital camera, via the cable or the network, via the I / F 307. The CPU 301 reads and analyzes the print data in the reception buffer included in the I / F 307, performs necessary image processing, data rearrangement processing, and the like in the ASIC 305, and transfers the image data to the head drive control unit 308. To do.

  When the head drive control unit 308 receives image data (dot pattern data) corresponding to one line of the recording head 24, the dot pattern data for one line is serialized to the head driver 309 in synchronization with the clock signal. Data is sent out, and a latch signal is sent to the head driver 309 at a predetermined timing. The head drive control unit 308 includes a ROM (which can also be configured by the ROM 302) that stores pattern data of a drive waveform (drive signal), and a D / A converter that D / A converts the drive waveform data read from the ROM. A waveform generation circuit including an A converter and a drive waveform generation circuit including an amplifier and the like are included.

  The head driver 309 is a shift register that inputs a clock signal from the head drive control unit 308 and serial data that is image data, and a latch circuit that latches a register value of the shift register using a latch signal from the head drive control unit 308. A level conversion circuit (level shifter) that changes the output value of the latch circuit, an analog switch array (switch means) that is controlled to be turned on / off by the level shifter, and the like, and controls on / off of the analog switch array. In this way, a required drive waveform included in the drive waveform is selectively applied to the actuator means of the recording head 24 to drive the head.

  Further, the control unit 300 controls the AC bias supply unit 316 to generate an alternating voltage having a voltage value for causing charging to generate a required suction force when the sheet 5 is sucked and transported by the transport belt 31. It is applied to the charging roller 34.

  Further, the control unit 300 performs on / off control of the heater 142 disposed above the sheet feeding cassette 41 via the driver 143 and the open / close switch 144 that can be externally operated based on the humidity detected by the humidity sensor 141. The open / close switch 144 is interposed in the power supply path to the heater 142, and the heater 142 can be forcibly turned off by an external operation.

  In this image forming apparatus configured as described above, as shown in FIG. 7, the rotation amount is controlled by an encoder 36 including a slit disk 334 and a photo sensor 335 provided at the end of the conveyance roller 32 that drives the conveyance belt 31. The sub-scan motor 131 is driven and controlled by the control unit 300 and the motor driving unit 312 according to the detected rotation amount, and the AC bias supply unit 316 supplies the charging roller 34 with positive and negative voltages. Apply a rectangular wave high voltage.

  Thus, since the charging roller 34 is in contact with the insulating layer (surface layer) 31 a of the transport belt 31, positive and negative charges alternately appear on the surface layer 31 a of the transport belt 31 with respect to the transport direction of the transport belt 31. It is applied in a band shape, and charging is performed on the conveying belt 21 with a predetermined charging width as shown in FIG. 7 to generate an unequal electric field. A combination of positive and negative charge widths is referred to as a “charge cycle length”.

  Therefore, the sheet 5 is fed from the sheet feeding unit 4 and is fed between the transport roller 32 and the presser roller 36, and an unequal electric field is generated by forming positive and negative charges on the surface layer 31a. When the paper 5 is fed onto the conveying belt 31, the paper 5 is instantly polarized in accordance with the direction of the electric field, and is attracted onto the conveying belt 31 by the electrostatic adsorption force, and is conveyed along with the movement of the conveying belt 31.

  Then, while the paper 5 is intermittently transported by the transport belt 31, recording liquid droplets are ejected from the recording head 24 onto the paper 5 to record (print) an image, and the front end of the paper 5 on which printing is performed The side is separated from the conveyance belt 31 by the separation claw 37 and sent to the paper discharge conveyance unit 6 by the conveyance roller 38.

Therefore, on / off control of the heater 142 during printing in the image forming apparatus will be described with reference to FIG.
When printing is started, it is determined whether or not the humidity of the paper 5 stored in the paper feed cassette 41 is equal to or higher than a predetermined value based on the detection signal of the humidity sensor 141. At this time, if the humidity of the paper 5 is not equal to or higher than the predetermined value, that is, if the humidity is lower than the predetermined value, the process proceeds to the paper feeding operation.

  On the other hand, if the humidity of the paper 5 is equal to or higher than a predetermined value, whether or not the droplet discharge amount (or printing rate) in the print data printed on the paper 5 to be fed is equal to or higher than the predetermined amount (predetermined value). Is determined. This droplet discharge amount can be obtained by estimating the total amount of droplets to be discharged based on the print data, or calculating the ratio (printing rate) of the area where an image is formed on one sheet of paper 5. Can do.

  If the droplet discharge amount (or printing rate) in the print data is not equal to or greater than a predetermined amount (predetermined value), the heater 142 is turned on for a predetermined time to heat the paper 5 stored in the paper feed cassette 41. Then, the paper feeding operation is started. In this case, a predetermined time (also referred to as a heating time or a dehumidifying time) for turning on the heater 142 can be set to a time corresponding to the humidity. For example, if the humidity is 60% RH, 1 minute is set for 70% RH, 2 minutes is set for 80% RH, and 3 minutes is set for 80% RH, so that the heater on time (heating time) is as short as possible. Thus, it is preferable to save power.

  In addition, after the heater 142 is turned on for a predetermined time, the humidity can be detected again by the humidity sensor 141, and in order to shorten the waiting time until paper feeding, the paper feeding operation is performed without performing humidity detection again. You can also move to. Further, it is possible to perform the humidity detection again in the case of the first sheet or the first sheet of continuous printing, and not to perform the humidity detection again in the second and subsequent sheets of continuous printing.

  On the other hand, when the droplet discharge amount (or printing rate) in the print data is greater than or equal to a predetermined amount (predetermined value), the heater 142 is not turned on even if the detected humidity is greater than or equal to the predetermined value. Then, the paper 5 stored in the paper feed cassette 41 is shifted to the paper feed operation without being heated and dried.

  That is, when the humidity of the paper 5 is high (above a predetermined value), the paper 5 can be heated and dried to suppress curling or the like during conveyance. In such a case, for example, when printing a solid image, a change in humidity occurs rapidly on the paper 5 so that cockling is likely to occur, and the paper 5 rubs against the recording head 24 during conveyance due to the cockling. As a result, the image quality deteriorates or a jam occurs.

  Therefore, as described above, when the amount of droplets to be ejected onto the paper 5 exceeds a predetermined amount (including when the printing rate exceeds a predetermined value), even if the humidity of the paper 5 is equal to or higher than the predetermined value. By not performing the heating by the heater 142, it is possible to prevent the image quality from deteriorating and suppress the curling while improving the transportability.

  Therefore, when an image using a large amount of recording liquid such as a solid image is often printed, the open / close switch 144 interposed in the power supply path to the heater 142 is operated from the outside of the apparatus main body 1. The heater 142 can be forcibly turned off by turning the open / close switch 144 off.

Next, charging control for the transport belt 31 will be described with reference to FIG.
Here, the humidity of the paper 5 stored in the paper feed cassette 41 is detected based on the detection signal of the humidity sensor 141, and it is determined whether or not the detected humidity is equal to or higher than a predetermined value. At this time, if the detected humidity of the paper 5 is not equal to or higher than the predetermined value, that is, if it is lower than the predetermined value, the charging control is performed on the conveyance belt 31 according to the detected humidity as it is.

  On the other hand, if the detected humidity of the paper 5 is equal to or higher than a predetermined value, the heater 142 is turned on for a predetermined time to heat and dry the paper 5 accommodated in the paper feed cassette 41 and detect the paper 5 again. It is determined whether or not the humidity is equal to or higher than a predetermined value, and when the detected humidity of the paper 5 is not higher than the predetermined value, that is, lower than the predetermined value, charging control is performed on the conveyance belt 31 according to the detected humidity.

  The charging control here is control for changing the charging cycle length (charging width). That is, as described above, when an alternating electric field is applied to the transport belt 31 to apply a charge, the attractive force to the paper depends not only on the magnitude of the applied voltage but also on the charging cycle length (or charging width) and the resistance value of the paper. Also changes. The resistance value of the paper and the humidity are correlated. In view of this, the charging control of the conveying belt 31 is performed with the charging cycle length that provides the required suction force by detecting the humidity of the paper.

1 is a schematic configuration diagram for explaining an image forming apparatus according to the present invention. FIG. 6 is an explanatory plan view of the image forming unit and the sub-scanning conveyance unit. FIG. 5 is an enlarged explanatory view of the sub-scanning conveyance unit. It is explanatory drawing with which it uses for description about the structure and charging of a conveyance belt. FIG. 6 is an explanatory diagram for explaining a sheet feeding unit. It is a block diagram explaining the outline | summary of the control part of an apparatus. It is explanatory drawing with which it uses for description of charging control of a conveyance belt. It is explanatory drawing with which it uses for description of the heater control at the time of printing. It is explanatory drawing with which it uses for description of the charging control of the conveyance belt based on detected humidity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 2 ... Image formation part 3 ... Sub-scanning conveyance part 4 ... Paper feed part 5 ... Paper (recording medium)
7: Paper discharge conveyance unit 8 ... Paper discharge tray (paper discharge unit)
DESCRIPTION OF SYMBOLS 11 ... Image reading part 21 ... Guide rod 22 ... Guide rail 23 ... Carriage 24 ... Recording head 31 ... Conveyance belt 32 ... Conveyance roller 34 ... Charging roller 141 ... Humidity sensor 142 ... Heater (heating means)
144 ... Switch

Claims (7)

  In an image forming apparatus that discharges droplets from a recording head to form an image on the recording medium, a storage unit that stores the recording medium, and heating that heats the recording medium stored in the storage unit For controlling the heating means based on the detection result of the humidity of the recording medium stored in the storage means and information relating to the ejection amount of droplets for forming an image on the recording medium And an image forming apparatus.   2. The image forming apparatus according to claim 1, wherein when the amount of liquid droplets for forming an image on the recording medium exceeds a predetermined amount, the recording by the heating unit regardless of the detection result of the humidity detection unit. An image forming apparatus characterized by not heating a medium.   3. The image forming apparatus according to claim 1, wherein the recording medium is adsorbed and conveyed by an electrostatic force generated by applying an electric charge on the conveying belt.   4. The image forming apparatus according to claim 3, wherein when the humidity detected by the humidity detector is less than a predetermined value, the application of electric charges to the transport belt is controlled based on the detected humidity, and the detected humidity is equal to or higher than a predetermined value. An image forming apparatus, wherein the recording medium is sometimes heated by the heating means.   5. The image forming apparatus according to claim 1, wherein the heating unit is disposed above the recording medium accommodated in the accommodating unit.   6. The image forming apparatus according to claim 1, further comprising an externally operable switch unit that opens and closes a power supply path to the heating unit. 7. The image forming apparatus according to claim 1, further comprising a document reading unit that reads a document.

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