JP2008155427A - Conveyance device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent stopping of a device due to detection of leakage by a constitution wherein the device is provided with a means for separating a charging means by driving a contacting/separating means in response to a sensing result of an environmental condition, and then the charging means is separated from a belt member by predicting the occurrence of dew condensation. <P>SOLUTION: In this conveyance device, when it is judged that the conveyance device is in an environment condition that dew condensation may occur on a conveyance belt 31 on the basis of current temperature data (t1) and the previous temperature data (t0) at a portion in the vicinity of the conveyance belt 31, a solenoid 205 in a contacting/separating mechanism section 201 for a charging roller 34 is turned on to separate the charging roller 34 from the conveyance belt 31. An operation for acquiring current temperature data (t2) after waiting a predetermined time period and for comparing the acquired current temperature data (t2) with the previous temperature data (t1), is repeated. The driving of the conveyance belt 31 and applying of a high voltage are not carried out until the environment may cause no dew condensation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a conveying apparatus and an image forming apparatus, and more particularly to a conveying apparatus that sucks and conveys a member to be conveyed by a belt member and an image forming apparatus including the conveying apparatus.

  In general, a printer, a fax machine, a copier, a plotter, or an image forming apparatus that combines a plurality of these functions includes, for example, a recording head composed of a liquid ejection head that ejects liquid droplets of recording liquid (liquid). Using a liquid ejection apparatus, while conveying a medium (hereinafter also referred to as “paper”, the material is not limited, and a recording medium, a recording medium, a transfer material, recording paper, and the like are also used synonymously). In some cases, a recording liquid (hereinafter also referred to as ink) as a liquid is attached to a sheet to form an image (recording, printing, printing, and printing are also used synonymously).

  The "image forming device" is a device that discharges liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, or other image forming agent. The image forming apparatus means an image forming apparatus, and “image forming” means not only an image having a meaning such as a character or a figure but also an image having no meaning such as a pattern. It also means giving to the medium. The “liquid” is not limited to the recording liquid and the ink, and is not particularly limited as long as it becomes a fluid when ejected.

  In addition, as a liquid ejection type image forming apparatus, a serial type image forming apparatus that scans a recording head mounted on a carriage to form an image and a single recording head having nozzle rows corresponding to the paper width are used. Alternatively, there is a line type image forming apparatus in which a plurality of heads are arranged and nozzle rows corresponding to the paper width are arranged to form an image without scanning the recording head.

  In such an image forming apparatus, there is an image forming apparatus that conveys a sheet by electrostatically attracting the sheet by charging a belt member and conveying the sheet by moving the belt member. In such a transport device that charges the belt member and electrostatically attracts the transported member, the belt member can be charged to a predetermined potential when a leak occurs between the belt member and the charging means. It will disappear and the transportability will deteriorate.

Therefore, Patent Document 1 includes a current monitor circuit that monitors current flowing from a high voltage power supply AC high voltage output unit through a charging roller, a conveyance belt, a conveyance roller, and a closed circuit represented by the AC high voltage output unit, It is described that a leak detection signal is output when a leak occurs and a current value increases, a leak is detected based on the leak detection signal, and necessary control is performed according to the detection result.
JP 2004-331276 A

Further, regarding the relationship between the charging means and the member to be charged, Patent Document 2 includes a contact / separation unit that performs contact / separation operation with respect to the photosensitive drum with a charging roller that applies a bias while contacting the photosensitive drum, An image forming apparatus is described in which a charging roller is brought into contact with a photosensitive drum only during charging and charging is performed.
JP 2004-246188 A

Similarly, in Patent Document 3, a conveyance belt that conveys a sheet to a plurality of image carriers, and a contact belt that is detachably contacted with the conveyance belt, and an electrostatic bias is applied to the sheet conveyed by the conveyance belt. Describes a printing apparatus provided with an adsorbing means for adsorbing to a conveyor belt.
JP 09-179419 A

  By the way, in the liquid discharge type image forming apparatus, when the recording liquid or water droplets at the time of dew condensation adheres to the surface of the belt member and adheres to the charging member as the belt rotates, depending on the amount of the recording liquid or water droplets attached, The resistance value of the charging member is expected to decrease. As a result, the current value from the high-voltage power source increases (due to low voltage control), the leakage current value increases, and leakage occurs between the belt member and the charging member. May be detected as having occurred.

  Unlike the original leak (short circuit), the leak detection due to the adhesion of the recording liquid and water droplets is performed even though the recording liquid and water return to normal when the liquid and water evaporate. Further, there arises a problem that the apparatus is stopped (standby state) due to the recording liquid and water droplets recovered with time.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a transport apparatus that reduces apparatus stoppage due to leak detection and an image forming apparatus including the transport apparatus.

  In order to solve the above-described problems, a conveying device according to the present invention includes an endless belt member that is wound around at least a driving roller and a driven roller, a charging unit that applies an electric field to the surface of the belt member, and the charging unit. Is configured to include a contacting / separating unit that contacts and separates the belt member surface and a unit that drives the contacting / separating unit based on the detection result of the environmental condition to separate the charging unit.

  Here, it can be set as the structure provided with the means to detect at least any one of environmental temperature and environmental humidity provided in the vicinity of the belt member. Moreover, it can be set as the structure whose environmental conditions are conditions which generate | occur | produce dew condensation.

  The conveying device according to the present invention includes an endless belt member wound around at least a driving roller and a driven roller, a charging unit that applies an electric field to the surface of the belt member, and the charging unit against the surface of the belt member. Contact / separation means for contacting and separating, and means for driving the contact / separation means to separate the charging means based on a detection result of a leak current in the power source that outputs a voltage applied to the belt member. .

  Here, it can be set as the structure which detects the leakage current when the applied voltage when conveying a to-be-conveyed member with respect to a belt member is applied. Moreover, it can be set as the structure which detects the leakage current when a voltage lower than the applied voltage when conveying a to-be-conveyed member with respect to a belt member is applied.

  The conveying device according to the present invention includes an endless belt member wound around at least a driving roller and a driven roller, a charging unit that applies an electric field to the surface of the belt member, and the charging unit against the surface of the belt member. The apparatus includes a contacting / separating unit that contacts and separates, and a unit that drives the contacting / separating unit to separate the charging unit when no voltage is applied to the belt member.

  The conveying device according to the present invention is charged by driving the contact / separation means during at least the endless belt member wound around the driving roller and the driven roller, and the belt cleaning operation for rotating the belt member in a state where no voltage is applied. And a means for separating the means.

  The conveying device according to the present invention includes an endless belt member that is wound around at least a driving roller and a driven roller, and a charging / disengaging unit that drives a contacting / separating unit when the trailing end of the conveyed member is attracted to the belt member. And a means for separating.

  The image forming apparatus according to the present invention includes the transport device according to the present invention. In this case, the image forming unit may include a liquid discharge head that discharges the recording liquid.

  According to the transport device of the present invention, the transport device according to the present invention includes a device that drives the contact / separation device to separate the charging device based on the detection result of the environmental condition. And stoppage of the apparatus due to leak detection can be reduced.

  According to the conveying device of the present invention, at least the endless belt member that is wound around the driving roller and the driven roller, the charging unit that applies an electric field to the surface of the belt member, and the charging unit to the surface of the belt member Contact / separation means for contacting and separating, and means for driving the contact / separation means to separate the charging means based on the detection result of the leak current in the power source that outputs the voltage applied to the belt member. The stoppage of the apparatus due to leak detection can be reduced.

  According to the conveying device of the present invention, at least the endless belt member that is wound around the driving roller and the driven roller, the charging unit that applies an electric field to the surface of the belt member, and the charging unit to the surface of the belt member The contact / separation means that abuts and separates, and the means that drives the contact / separation means to separate the charging means when no voltage is applied to the belt member. it can.

  The conveying device according to the present invention drives the contact / separation means during at least the endless belt member wound around the driving roller and the driven roller, and the belt cleaning operation of rotating the belt member in a state where no voltage is applied. And a means for separating the charging means, it is possible to reduce apparatus stoppage due to leak detection.

  According to the transport device of the present invention, the endless belt member wound around at least the driving roller and the driven roller and the contact / separation means are driven and charged when the rear end of the transported member is attracted to the belt member. And a means for separating the means, it is possible to reduce apparatus stoppage due to leak detection.

  According to the image forming apparatus of the present invention, since the transport apparatus according to the present invention is provided, apparatus stoppage due to leak detection is reduced.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of the image forming apparatus according to the present invention including the conveying 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 a plan explanatory view of an engine unit portion of the apparatus, and FIG. 3 is a front explanatory view of the engine unit portion.

  The image forming apparatus includes an image forming unit (means) 2 for forming an image inside the apparatus main body 1 (an enclosure), a sub-scanning conveying unit (means) 3 constituted by the conveying device according to the present invention, and the like. However, the material is not limited to paper, although it is referred to as a recording medium (hereinafter referred to as “paper”) that is a transported member from a paper feeding unit (means) 4 that is a housing means provided at the bottom of the apparatus main body 1. ) 5 are separated and fed one by one, and droplets are ejected onto the sheet 5 by the image forming unit 2 while the sheet 5 is intermittently conveyed by the sub-scanning conveying unit 3 at a position facing the image forming unit 2. After forming (recording) a required image, 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 unit 2 and the sub-scanning conveyance unit 3 are unitized to form an engine unit 100 that is detachably attached to the apparatus main body 1.

  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.

  Here, as shown in FIG. 2, the image forming section 2 of the image forming apparatus includes a carriage guide (guide rod) 21 that is a main guide member horizontally mounted between the front side plate 101F and the rear side plate 101R and the rear side. A guide stay 22 (see FIGS. 3 and 4), which is a slave guide member provided on the stay 101B side, holds the carriage 23 so as to be movable in the main scanning direction, and the main scanning motor 27 connects the drive pulley 28A and the driven pulley 28B. Is moved and scanned in the main scanning direction via a timing belt 29 spanned between the two.

  On the carriage 23, recording heads 24k1 and 24k2 each composed of two droplet discharge heads for discharging black (K) ink, cyan (C) ink, magenta (M) ink, and yellow (Y). A total of five droplet ejection heads, recording heads 24c, 24m, and 24y each composed of one droplet ejection head that ejects ink (when not distinguishing colors and collectively referred to as “recording head 24”), are included. A shuttle type is mounted, in which the carriage 23 is moved in the main scanning direction, and droplets are ejected from the recording head 24 while the paper 5 is fed in the paper transporting direction (sub-scanning direction) by the sub-scanning transport unit 3. Yes.

  In addition, a sub tank 25 is mounted on the carriage 23 in order to supply a recording liquid of a required color to each recording head 24. 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, and ink (recording liquid) is supplied from each color ink cartridge 26 to each color sub-tank 25 via a tube (not shown). 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.

  Further, as shown in FIG. 2, a linear scale 128 having a slit formed between the front side plate 101 </ b> F and the rear side plate 101 </ b> R along the main scanning direction of the carriage 23 is stretched. An encoder sensor 129 made up of a transmissive photosensor for detecting the slit is provided, and the linear scale 128 and the encoder sensor 129 constitute a linear encoder that detects the movement of the carriage 23.

  Further, as shown in FIG. 2, a maintenance / recovery mechanism (device) 121 for maintaining and recovering the nozzle state of the recording head 24 is disposed in the non-printing area on one side of the carriage 23 in the scanning direction. . The maintenance / recovery mechanism 121 is a cap member for capping each nozzle surface 24a of the five recording heads 24, and includes one suction cap 122a that also serves as a moisture retention, and four moisture retention caps 122b to 122e. A wiper blade 124, which is a wiping member for wiping the nozzle surface 24a of the recording head 24, and an idle ejection receiver 125 for performing idle ejection are disposed.

  Further, an idle ejection receptacle 126 for performing idle ejection is disposed in the non-printing area on the other side of the carriage 23 in the scanning direction. Openings 127 a to 127 e are formed in the idle discharge receptacle 126.

  The sub-scanning conveyance unit 3 conveys the paper 5 that is a sheet material fed from below from the lower side by a conveyance roller 32 that is a driving roller for conveying the sheet 5 so as to face the image forming unit 2 while changing the conveyance direction by approximately 90 degrees. And an endless transport belt 31 laid between a tension roller and a driven roller 33 as a tension roller, and a charging roller 34 as a charging means to which an AC bias voltage as an alternating voltage is applied to charge the surface of the transport belt 31. A platen guide member 35 that guides the conveyance belt 31 in a region facing the image forming unit 2, and a first pressure roller (inlet pressure roller) that presses the sheet 5 toward the conveyance belt 31 at a position facing the conveyance roller 32. ) 36, and the sheet 5 is pressed against the platen guide member 35 between the conveyance roller 32 and the recording head 34 which is an image forming unit. 2 pressing roller (tip pressing roller) 37, and a separation claw 39 for separating the sheet 5 on which an image is formed from the transport belt 31 by the image forming unit 2.

  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. Further, as shown in FIG. 3, a cleaning member 135 that removes the paper dust on the transport belt 31 and a static elimination member 136 that neutralizes the surface of the transport belt 31 are provided.

  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 registration roller pair 44 for registering the sheet 5 to be fed are provided.

  The paper feed unit 4 includes a manual feed tray 46 for stacking and storing a large number of sheets 5, a manual feed roller 47 for feeding the sheets 5 from the manual feed tray 46 one by one, and the apparatus main body 1. On the lower side, an optional paper feed cassette and a vertical transport roller 48 for transporting the paper 5 fed from the duplex unit are provided. Members for feeding the paper 5 to the sub-scanning conveying unit 3 such as the paper feeding roller 42, the registration roller 44, the manual feeding roller 47, and the vertical conveying roller 48 are a paper feeding made of an HB type stepping motor via an electromagnetic clutch (not shown). The motor (drive means) 49 is rotationally driven.

  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.

  In the image forming apparatus configured as described above, the rotation amount of the conveyance roller 32 that drives the conveyance belt 31 is detected, and the sub-scanning motor 131 is driven and controlled according to the detected rotation amount, and an AC (not shown) is also illustrated. A positive and negative rectangular wave high voltage, which is an alternating voltage, is applied from the bias supply unit to the charging roller 34, whereby positive and negative charges are alternately band-shaped in the conveying direction of the conveying belt 31. And is charged with a predetermined charging width on the conveying belt 31 to generate an unequal electric field.

  Therefore, the conveyance belt in which an unequal electric field is generated by the sheet 5 being fed from the sheet feeding unit 4 and fed between the conveyance roller 32 and the pressing roller 36 to form positive and negative charges. When fed onto the paper 31, the paper 5 is instantly polarized according to the direction of the electric field, and is attracted onto the transport belt 31 by the electrostatic attraction force, and is transported as the transport belt 31 moves.

  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.

  During printing (recording) standby, the carriage 23 is moved to the maintenance / recovery mechanism 121 side, and the nozzle surface of the recording head 24 is capped by the cap 122, and the nozzles are kept in a wet state. To prevent. In addition, the recording liquid is sucked from the nozzle in a state where the recording head 24 is capped by the suction and moisture retention cap 122a (referred to as “nozzle suction” or “head suction”), and the recovered recording liquid and bubbles are discharged. Wiping is performed by the wiper blade 124 in order to clean and remove ink adhering to the nozzle surface of the recording head 24 by this recovery operation. In addition, a blank ejection operation is performed in which ink that is not related to printing is ejected toward the blank ejection receiver 125 before recording is started or during recording. Thereby, the stable ejection performance of the recording head 24 is maintained.

Therefore, the contacting / separating means of the charging roller 34 in this image forming apparatus will be described with reference to FIG. FIG. 4 is an explanatory view showing the contact / separation means.
The contact / separation mechanism unit 201 serving as the contact / separation unit contacts (contacts) and separates the charging roller 34 serving as the charging unit with respect to the conveyance belt 31 serving as the belt member. In this contact / separation mechanism 201, a roller holding member 202 that rotatably holds the charging roller 34 at one end portion is supported by a support shaft 203 so as to be swingable, and one end portion side of the roller holding member 202 is disposed on the charging roller 34. Energizing means 204 such as a spring energizing in a direction away from the conveyor belt 31 and a solenoid having a plunger 205 a that swings the other end of the roller holding member 202 against the energizing force of the energizing means 204. 205.

Next, a portion for controlling the contact and separation of the charging roller 34 by driving the contact and separation mechanism 201 will be described with reference to the block diagram of FIG.
The main control unit 301 controls the entire image forming apparatus and includes a microcomputer including a CPU, a ROM, a RAM, a VRAM, an I / O, and the like. The main control unit 301 controls the high-voltage power supply control unit 302 and the contact / separation mechanism control unit 303.

  The high voltage power supply control unit 302 applies a high voltage (AC bias voltage) to the charging roller 34 based on the detection result from the conveyance belt speed detection unit 304 that detects the speed of the conveyance belt 31. (Supply unit) 305 is controlled to control charging of the conveying belt 31 by the charging roller 34. The contact / separation mechanism control unit 303 drives and controls the solenoid 205 of the contact / separation mechanism unit 201 to bring the charging roller 34 into contact with or away from the transport belt 31.

  The leak current detection unit 306 detects the leak current of the high voltage power supply 305 and sends it to the main control unit 301. Further, the temperature detection unit 311 detects the temperature near the conveyor belt 31 and stores the detected temperature data in the storage unit 313 sequentially. The humidity means 312 detects the humidity near the conveyor belt 31 and stores the detected humidity data in the storage means 313 sequentially.

  The main control unit 301 determines whether or not a leak has occurred from the detection result of the leakage current detection unit 306, determines environmental conditions based on temperature data and humidity data stored in the storage unit 313, and The contact / separation mechanism unit 201 controls the contact / separation of the charging roller 34 through the separation mechanism control unit 303.

Next, a first example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the current temperature data (t1) in the vicinity of the conveyance belt 31 is obtained from the temperature detection means 311 while the conveyance belt 31 is stopped, and the previous temperature data stored in the storage means (memory) 313 is obtained. Compared with (t0), it is determined whether or not t1 <t0.

  At this time, if t1 <t0, the temperature in the vicinity of the conveyance belt 31 is lowered, and it is not a condition that condensation occurs on the surface of the conveyance belt 31, so the contact / separation mechanism 201 of the charging roller 34 The solenoid 205 starts driving the conveying belt 31 in an OFF state (a state where the charging roller 34 is in contact with the conveying belt 31: a contact state), applies an AC bias from the high voltage power source 305, and By setting the suctionable state, the recording medium can be transported (conveyance preparation completed).

  On the other hand, if t1 <t0, that is, if t1> t0, the temperature in the vicinity of the conveyor belt 31 has risen, and condensation may occur on the surface of the conveyor belt 31. Therefore, the solenoid 205 of the contact / separation mechanism portion 201 of the charging roller 34 is turned on, the charging roller 34 is separated from the conveying belt 31 (separated state), and after waiting for a certain period of time, the current temperature data (t2) is again displayed. ) And is compared with the immediately preceding temperature data (t1). If t2 <t1, the contact / separation mechanism 201 is turned off (contact state), and the conveyance belt 31 is driven and high-voltage power is applied in the same manner as described above to bring the conveyance ready state. On the other hand, if t2> t1, the temperature is measured again after a certain period of time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until an environment where no dew condensation occurs.

  As described above, the charging means can be brought into and out of contact with the belt-shaped member, and the means for driving the contacting and separating means based on the detection result of the environmental condition to separate the charging means is provided. The environment that is likely to occur can be predicted, the charging member can be separated in advance, and the stoppage (equipment down) caused by leak detection due to water droplet adhesion during dew condensation that can be recovered can be reduced.

Next, a second example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the first example starts from the state where the conveyor belt is stopped, but starts after the conveyor belt rotates.
That is, the driving of the conveyor belt 31 is started in a state where the contact / separation mechanism unit 201 is in the OFF state and the charging roller 34 is in contact with the conveyor belt 31, and then the current temperature data (t1) in the vicinity of the conveyor belt 31 is obtained. Compared with the previous temperature data (t0) obtained from the temperature detection means 313 and stored in the storage means (memory) 313, it is determined whether or not t1 <t0.

  At this time, if t1 <t0, the temperature in the vicinity of the conveyor belt 31 has decreased, and this is not a condition for causing condensation on the surface of the conveyor belt 31, so the AC bias from the high-voltage power supply 305 is applied as it is. Then, the conveyance belt 31 is brought into a suckable state, so that the recording medium can be conveyed (preparation for conveyance).

  On the other hand, if t1 <t0, that is, if t1> t0, the temperature in the vicinity of the conveyor belt 31 has risen, and condensation may occur on the surface of the conveyor belt 31. Therefore, the contact / separation mechanism portion 201 of the charging roller 34 is turned on to separate the charging roller 34 from the conveying belt 31, and after waiting for a certain period of time, the current temperature data (t2) is obtained again, and the previous temperature Compare with data (t1). If t2 <t1, the contact / separation mechanism 201 is turned off (contact state), high voltage power supply is applied in the same manner as described above, and the conveyance ready state is set. On the other hand, if t2> t1, the temperature is measured again after a certain period of time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until an environment where no dew condensation occurs.

  By separating the charging means based on humidity as in the first and second examples, the charging means can be separated according to conditions that cause dew condensation with simpler control, thereby reducing equipment down. .

Next, a third example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the current humidity data (h1) in the vicinity of the conveyor belt 31 is obtained from the humidity detecting means 312 and the previous humidity data stored in the storage means (memory) 313 while the conveyor belt 31 is stopped. Compared with (h0), it is determined whether or not h1 <h0.

  At this time, if h1 <h0, the humidity in the vicinity of the conveyor belt 31 is reduced, and it is not a condition for condensation to occur on the surface of the conveyor belt 31, so the contact / separation mechanism 201 of the charging roller 34 The solenoid 205 starts driving the conveying belt 31 in an OFF state (a state where the charging roller 34 is in contact with the conveying belt 31: a contact state), applies an AC bias from the high voltage power source 305, and By setting the suctionable state, the recording medium can be transported (conveyance preparation completed).

  On the other hand, if h1 <h0 is not satisfied, that is, if h1> h0, the humidity in the vicinity of the conveyor belt 31 is increased, and condensation may occur on the surface of the conveyor belt 31. Therefore, the solenoid 205 of the contact / separation mechanism portion 201 of the charging roller 34 is turned on, the charging roller 34 is separated from the conveying belt 31 (separated state), and after waiting for a certain period of time, the current humidity data (h2) is again displayed. ) And compared with the previous humidity data (h1). If h2 <h1, the contact / separation mechanism 201 is turned off (contact state), and the conveyance belt 31 is driven and a high-voltage power supply is applied in the same manner as described above to bring the conveyance ready state. On the other hand, if h2> h1, the humidity is measured again after a certain time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until an environment where no dew condensation occurs.

Next, a fourth example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the third example starts from a state where the conveyor belt is stopped, but starts after the conveyor belt rotates.
That is, the driving of the conveyor belt 31 is started in a state where the contact / separation mechanism unit 201 is in the OFF state and the charging roller 34 is in contact with the conveyor belt 31, and then the current humidity data (h1) near the conveyor belt 31 is obtained. Compared with the previous humidity data (h0) obtained from the humidity detection means 312 and stored in the storage means (memory) 313, it is determined whether or not h1 <h0.

  At this time, if h1 <h0, the humidity in the vicinity of the conveyor belt 31 has decreased, and it is not a condition for dew condensation to occur on the surface of the conveyor belt 31, so that an AC bias application from the high-voltage power supply 305 is applied as it is. Then, the conveyance belt 31 is brought into a suckable state, so that the recording medium can be conveyed (preparation for conveyance).

  On the other hand, if h1 <h0 is not satisfied, that is, if h1> h0, the humidity in the vicinity of the conveyor belt 31 is increased, and condensation may occur on the surface of the conveyor belt 31. Therefore, the contact / separation mechanism 201 of the charging roller 34 is turned on to separate the charging roller 34 from the conveyor belt 31, and after waiting for a certain period of time, the current humidity data (h2) is obtained again, and the previous humidity Compare with data (h1). If h2 <h1, the contact / separation mechanism 201 is turned off (contact state), high voltage power supply is applied in the same manner as described above, and the conveyance ready state is set. On the other hand, if h2> h1, the humidity is measured again after a certain time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until an environment where no dew condensation occurs.

  By separating the charging means based on the humidity as in the third and fourth examples, the charging means can be separated according to conditions that cause dew condensation with simpler control, and equipment down can be reduced. .

Next, a fifth example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the current temperature data (t1) in the vicinity of the conveyance belt 31 is obtained from the temperature detection means 311 and the current humidity data (h1) is obtained from the humidity detection means 312 in the state where the conveyance belt 31 is stopped, and stored. Compared with the previous temperature / humidity data (t0, h0) stored in the means (memory) 313, as shown in FIG. That is, when t0> t1, the current humidity data h1 is non-condensing regardless of whether h1 <h0 or h1> h0. If t0 <t1, the current humidity data h1 is h1 <h0. If there is any non-condensing condition, and if h1> h0, the dewing condition is set.

  At this time, if it is a non-condensing condition, the solenoid 205 of the contact / separation mechanism portion 201 of the charging roller 34 remains in an OFF state (a state where the charging roller 34 is in contact with the conveyance belt 31: a contact state). Driving is started, an AC bias is applied from the high-voltage power supply 305, and the conveyance belt 31 is brought into a suckable state, so that the recording medium can be conveyed (conveyance preparation completed).

  On the other hand, if there is no non-condensing condition, dew condensation may occur on the surface of the conveyor belt 31, so the solenoid 205 of the contact / separation mechanism 201 of the charging roller 34 is turned on and the charging roller 34 is turned on. Separated from the conveyor belt 31 (separated state), waits for a certain period of time, obtains the current temperature / humidity data (t2, h2) again, and does not condense compared to the previous temperature / humidity data (t2, h1). Determine whether the condition is met.

  And if it is a non-condensing condition, the contact-and-separation mechanism part 201 will be made into an OFF state (contact state), the conveyance belt 31 will be driven, high voltage power supply will be implemented, and it will be in a conveyance preparation completion state. On the other hand, if the non-condensing condition is not satisfied, the temperature and humidity are measured again after a certain time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until the non-condensing condition is reached.

Next, a sixth example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
Here, the fifth example starts from a state where the conveyor belt is stopped, but starts after the conveyor belt rotates.
That is, the driving of the conveyor belt 31 is started in a state where the contact / separation mechanism unit 201 is in the OFF state and the charging roller 34 is in contact with the conveyor belt 31, and then the current temperature data (t1) in the vicinity of the conveyor belt 31 is obtained. The humidity data (h1) is obtained from the temperature detection means 311 from the humidity detection means 312 and compared with the previous temperature / humidity data (t1, h0) stored in the storage means (memory) 313, as shown in FIG. It is determined whether or not it is a non-condensing condition given by the relationship as shown in FIG.

  At this time, if it is a non-condensing condition, an AC bias is applied from the high-voltage power supply 305 as it is, and the conveyance belt 31 is brought into a suckable state, so that the recording medium can be conveyed (conveyance preparation is completed).

  On the other hand, if there is no non-condensing condition, dew condensation may occur on the surface of the conveyor belt 31, so that the contact / separation mechanism portion 201 of the charging roller 34 is turned on to move the charging roller 34 from the conveyor belt 31. After a certain time has passed, the current temperature / humidity data (t2, h2) is obtained again, and compared with the previous temperature / humidity data (t1, h1) to determine whether or not there is a non-condensing condition. .

  And if it is a non-condensing condition, the contact-and-separation mechanism part 201 will be made into an OFF state (contact state), a high voltage power supply application will be implemented, and it will be in a conveyance preparation completion state. On the other hand, under the non-condensing condition, the temperature and humidity are measured again after a predetermined time has elapsed, and the conveyance belt 31 is not driven and the high-voltage power supply is not applied until an environment in which no dew condensation occurs.

  By separating the charging means based on the dew condensation conditions as in the fifth and sixth examples, the charging means can be separated more accurately according to the conditions that cause the dew condensation, thereby reducing equipment down.

Next, a seventh example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
First, the driving of the conveyor belt 31 is started, the contact / separation mechanism 201 is turned off, the charging roller 34 is brought into contact with the conveyor belt 31, and an AC bias is applied from the high voltage power source 305. Then, the leak current value output from the leak current value detection unit 306 is taken in and compared with the specified value, and it is determined whether or not the leak current value is equal to or less than the specified value.

  At this time, if the leak detection current value output is equal to or less than the specified value, the transport operation is continued as it is. On the other hand, if the leak detection current value output exceeds the specified value, the contact / separation mechanism portion 201 of the charging roller 34 is turned on to move the charging roller 34 away from the transport belt 31 and the output of the high voltage power source 205 is output. In a stopped state, the conveyor belt 31 is rotated for a certain time, and then the contact / separation mechanism unit 201 is turned off (contact state) again, bias is applied from the high voltage power supply 305, and leakage from the high voltage power supply 305 is performed. The process returns to the process of monitoring the detected current value output and comparing it with the specified value, and this process is repeated until the leak detected current value output becomes equal to or lower than the specified value.

  By monitoring the leakage current value at the high voltage power supply applied to the conveyor belt in this way, it is possible to predict the attachment of recording liquid and water droplets that lower the resistance value. Can be reduced.

Next, an eighth example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
First, the driving of the conveying belt 31 is started, the contact / separation mechanism 201 is turned off, the charging roller 34 is brought into contact with the conveying belt 31, and the AC bias voltage (this is lower than that during normal sheet conveyance from the high voltage power source 305). "Pre-bias") is applied. Then, the leak current value output from the leak current value detection unit 306 is taken in and compared with the specified value, and it is determined whether or not the leak current value is equal to or less than the specified value.

  At this time, if the leak detection current value output is equal to or less than the specified value, a normal AC bias is applied from the high voltage power supply 305 and the carrying operation is continued. On the other hand, if the leak detection current value output exceeds the specified value, the contact / separation mechanism portion 201 of the charging roller 34 is turned on to move the charging roller 34 away from the transport belt 31 and the output of the high voltage power source 205 is output. In a stopped state, the conveyor belt 31 is rotated for a certain period of time, and then the contact / separation mechanism unit 201 is again turned off (contacted), and a pre-bias is applied from the high-voltage power source 305. The process returns to the process of monitoring the leak detection current value output and comparing it with the specified value, and this process is repeated until the leak detected current value output becomes equal to or less than the specified value.

  In this way, by monitoring the leakage current value of the high-voltage power supply applied to the conveyor belt, it is possible to predict the attachment of recording liquid and water droplets that lower the resistance value. In addition to being able to reduce, monitoring the leak current value by applying a low-pressure pre-bias can suppress deterioration of the transport belt and the charging means when a leak occurs.

Next, a ninth example of charging roller contact / separation control will be described with reference to the flowchart of FIG.
First, the driving of the conveyor belt 31 is started, the contact / separation mechanism portion 201 is turned off, the charging roller 34 is brought into contact with the conveyor belt 31, and an AC bias voltage is applied from the high voltage power source 305. Then, it is determined whether or not to shift to a belt cleaning operation.

  When the belt cleaning operation is started, the contact / separation mechanism portion 201 of the charging roller 34 is turned on, the charging roller 34 is separated from the transport belt 31, and the output of the high-voltage power source 205 is stopped for a predetermined time. After performing the operation, the conveying belt 31 is stopped. On the other hand, when the belt cleaning operation is not performed, the conveying operation is continued.

  In other words, when the conveyor belt is driven during belt cleaning (charging application OFF), if the conveyor belt rotates when ink adheres to the conveyor belt or there is water droplets due to condensation, the conveyor belt simply contacts the charging means. As a result, the charging means becomes dirty. In addition, since the charging voltage is not applied during the belt cleaning, the leakage current cannot be monitored, so that contamination is promoted. Therefore, it is necessary to separate the charging roller during belt cleaning regardless of conditions.

  Thus, when no bias is applied to the transport belt from the charging unit (for example, during a belt cleaning operation), the charging unit is separated to further reduce equipment down.

Next, a tenth example of the contact / separation control of the charging roller will be described with reference to the flowchart of FIG.
First, the driving of the conveyor belt 31 is started, the contact / separation mechanism portion 201 is turned off, the charging roller 34 is brought into contact with the conveyor belt 31, and an AC bias voltage is applied from the high voltage power source 305. Then, it is determined whether or not the rear end of the recording medium is attracted onto the conveyance belt 31.

  At this time, if the rear end of the medium is not sucked onto the transport belt 31, the transport operation is continued until the rear end of the medium is sucked onto the transport belt 31. However, strictly speaking, the charging can be turned off from the time corresponding to the distance from the position of the charging roller 34 to the position of the conveyance belt 31 to which the sheet is attracted.

  On the other hand, if the rear end of the medium is adsorbed on the conveyance belt 31, the contact / separation mechanism portion 201 of the charging roller 34 is turned on to separate the charging roller 34 from the conveyance belt 31, and With the output stopped, the conveyance belt 31 is stopped after the passage of time for the medium to pass over the conveyance belt 31.

  As described above, when the recording medium is conveyed by the conveying belt, the charging unit is separated after the trailing end of the recording medium is attracted to the conveying belt, so that the apparatus down due to the leak detection can be further reduced. Further, by suppressing the conveyance belt and the charging unit to the minimum necessary contact, it is possible to prevent a decrease in resistance value due to a disturbance such as dirt.

  In the above-described embodiment, the present invention has been described with reference to an example in which the present invention is applied to a multifunction (MFP) image forming apparatus. However, the present invention can be similarly applied to other image forming apparatuses such as a printer and a facsimile apparatus. The present invention can also be applied to an image forming apparatus that uses a recording liquid other than ink.

1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus according to the present invention including a conveying device according to the present invention. It is plane explanatory drawing of the engine unit part of the same apparatus. It is front explanatory drawing of an engine unit part similarly. It is explanatory drawing with which it uses for description of the contacting / separating mechanism part of a charging roller similarly. FIG. 6 is a block diagram of a portion related to contact / separation control between the conveyance belt and the charging roller. It is a flowchart with which it uses for description of the 1st example of charging roller contact / separation control in the apparatus. FIG. 6 is a flowchart for explaining a second example of the charging roller contact / separation control. FIG. 6 is a flowchart for explaining a third example of the charging roller contact / separation control. FIG. 10 is a flowchart for explaining a fourth example of the charging roller contact / separation control. FIG. 10 is a flowchart for explaining a fifth example of the charging roller contact / separation control. FIG. 10 is a flowchart for explaining a sixth example of the charging roller contact / separation control. It is explanatory drawing of the dew condensation condition / non-condensation condition provided for description of a 5th example and a 6th example. It is a flowchart with which it uses for description of the 7th example of contact roller separation control of the apparatus. FIG. 10 is a flowchart for explaining an eighth example of charge roller contact / separation control. FIG. 10 is a flowchart for explaining a ninth example of contact roller separation control in the same manner. It is a flowchart with which it uses for description of the 10th example of contact roller separation control similarly.

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)
DESCRIPTION OF SYMBOLS 6 ... Paper discharge conveyance part 7 ... Paper discharge tray 11 ... Image reading part 23 ... Carriage 24 ... Recording head 31 ... Conveyance belt 32 ... Conveyance roller 33 ... Driven roller 34 ... Charging roller (charging means)
35 ... Platen guide member 41 ... Paper feed cassette 201 ... Contact / separation mechanism unit 205 ... Solenoid 302 ... High voltage power source control unit 303 ... Contact / separation mechanism control unit 305 ... High voltage power source 306 ... Leakage current detection unit

Claims (12)

An endless belt member wound around at least the driving roller and the driven roller;
Charging means for applying an electric field to the surface of the belt member;
Contact / separation means for contacting and separating the charging means with respect to the belt member surface;
And a means for driving the contact / separation means based on the detection result of the environmental condition to separate the charging means.   2. The conveying apparatus according to claim 1, further comprising means for detecting at least one of environmental temperature and environmental humidity provided in the vicinity of the belt member.   3. The transport apparatus according to claim 1, wherein the charging unit is separated when the environmental condition is a condition that causes dew condensation. An endless belt member wound around at least the driving roller and the driven roller;
Charging means for applying an electric field to the surface of the belt member;
Contact / separation means for contacting and separating the charging means with respect to the belt member surface;
A conveying device comprising: means for driving the contacting / separating means based on a detection result of a leak current in a power source that outputs a voltage applied to the belt member to separate the charging means.   The transport apparatus according to claim 4, wherein the leak current is detected when an applied voltage for transporting a transported member to the belt member is applied.   The transport apparatus according to claim 4, wherein the leak current is detected when a voltage lower than an applied voltage for transporting the transported member to the belt member is applied.   7. The transport apparatus according to claim 4, wherein the voltage applied to the belt member is an alternating voltage. An endless belt member wound around at least the driving roller and the driven roller;
Charging means for applying an electric field to the surface of the belt member;
Contact / separation means for contacting and separating the charging means with respect to the belt member surface;
And a means for driving the contact / separation means to separate the charging means when no voltage is applied to the belt member. An endless belt member wound around at least the driving roller and the driven roller;
Charging means for applying an electric field to the surface of the belt member;
Contact / separation means for contacting and separating the charging means with respect to the belt member surface;
And a means for driving the contacting / separating means to separate the charging means during a belt cleaning operation in which the belt member is rotated in a state where no voltage is applied. An endless belt member wound around at least the driving roller and the driven roller;
Charging means for applying an electric field to the surface of the belt member;
Contact / separation means for contacting and separating the charging means with respect to the belt member surface;
And a means for driving the contacting / separating means to separate the charging means when the rear end of the conveyed member is attracted to the belt member.   11. The image forming apparatus for forming an image by an image forming unit while electrostatically attracting a recording medium by a belt member of the conveying apparatus and conveying the recording medium, wherein the conveying apparatus is the conveying apparatus according to claim 1. An image forming apparatus.   12. The image forming apparatus according to claim 11, wherein the image forming unit includes a liquid discharge head for discharging a recording liquid.

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