JP2016110780A - Destaticizing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a destaticizing device and an image forming device that can destaticize a sheet while preventing occurrence of unevenness in humidification and suppressing increase of the device size.SOLUTION: A destaticizing device (image forming device) has an ion forming part for forming ions, a droplet forming part for forming droplets from liquid, an air stream forming part for forming an air stream, and a controller for controlling the ion forming part, the droplet forming part and the air stream forming part so that ions and droplets are supplied to a toner image formed on a sheet by an air stream.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a static eliminator and an image forming apparatus.

  In general, an image forming apparatus (printer, copier, facsimile, etc.) using an electrophotographic process technology generates an electrostatic latent image by irradiating (exposing) a charged photoconductor with a laser beam based on image data. Form. Then, by supplying toner from the developing device to the photosensitive member (image carrier) on which the electrostatic latent image is formed, the electrostatic latent image is visualized to form a toner image. Further, after the toner image is directly or indirectly transferred to the paper, the image is formed on the paper by fixing by heating and pressing with a fixing device. The paper that has passed through the fixing device passes through a pair of paper discharge rollers for discharge and is discharged onto a paper discharge tray.

  Further, during continuous printing in which image formation is continuously performed on a plurality of sheets, sheets as a plurality of printed output products are stacked and placed on a discharge tray. At this time, in the toner image (toner layer) formed on each sheet on the paper discharge tray, for example, the charge applied during the transfer may remain in the toner layer even after the fixing process. Since the toner layer has a high resistance value, particularly in an image forming apparatus having a high image forming process speed, the paper that has passed through the fixing device is discharged onto a paper discharge tray without sufficient self-discharge. When a plurality of sheets are continuously stacked and placed on the discharge tray, the air between the sheets is released due to the weight of the sheets, and the distance between the toner layers is reduced. As a result, the electrostatic attractive force between the sheets increases with time, and the adjacent sheets stick to each other via the toner image on the sheets (hereinafter referred to as “discharge pasting phenomenon”). ) Occurred. This paper discharge sticking phenomenon occurs remarkably when the temperature and humidity environment of the image forming apparatus is a low temperature and low humidity environment, or when the print mode is the duplex printing mode. When a paper discharge sticking phenomenon occurs, a paper transport failure occurs when a follow-up process (a process of forming an image using toner on a substrate onto which a foil has been transferred and fixing the formed toner image) is performed as a subsequent process. Occurs.

  In order to solve the above problems, a humidifying unit that humidifies the paper on which the fixing process has been performed is provided to promote the self-neutralization of the toner layer on the paper, or a static eliminating unit (for example, on the downstream side of the fixing device in the paper transport direction). (See Japanese Patent Application Laid-Open No. H10-228707), and proposed a configuration for removing the charge remaining in the toner layer on the paper.

Japanese Patent Laid-Open No. 02-23384

  However, it may be insufficient to neutralize each sheet on the paper discharge tray by providing only one of the humidifying unit and the neutralizing unit described above. For example, when the print coverage of a toner image formed on a sheet is high, or when the process speed of the image forming apparatus is high, there is a possibility that a paper discharge sticking phenomenon may occur.

  In view of this, there has been proposed a configuration in which a humidifying unit is provided on the upstream side of the neutralizing unit in the paper conveyance direction to assist the neutralizing function of the neutralizing unit as a configuration combining the humidifying unit and the neutralizing unit. However, when the paper is humidified by the humidifying means, the toner layer has a high hydrophobicity, and moisture adhering to the toner layer collects, so that humidification unevenness may occur. In this case, there has been a problem that a desired static elimination function by the static elimination means may not be ensured. Further, since the humidifying means and the static eliminating means are separate, a paper transport path corresponding to each of them is required, and there is a problem that the apparatus becomes large.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a static eliminator and an image forming apparatus that can neutralize a sheet while preventing the occurrence of humidification unevenness and suppressing the enlargement of the apparatus.

The static eliminator according to the present invention is
An ion forming part for forming ions;
A droplet forming section for forming droplets from a liquid;
An air flow forming part for forming an air flow;
A control unit for controlling the ion forming unit, the droplet forming unit, and the air flow forming unit so as to supply the ions and the droplets by the air flow to a toner image formed on a sheet; ,
Is provided.

An image forming apparatus according to the present invention includes:
A fixing unit for fixing the toner image on the paper;
A paper discharge unit that is provided on the downstream side in the paper transport direction and discharges the paper on which the toner image is fixed;
With
The static eliminator is provided between the fixing unit and the paper discharge unit.

  According to the present invention, it is possible to remove static electricity while preventing occurrence of humidification unevenness and suppressing an increase in size of the apparatus.

1 is a diagram schematically showing an overall configuration of an image forming apparatus in the present embodiment. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus according to the present embodiment. It is a figure which shows the structure of the static elimination apparatus in this Embodiment. It is a figure which shows the structure of the electrode which the static elimination apparatus in this Embodiment has. It is a figure which shows the structure of the electrode which the static elimination apparatus in this Embodiment has. It is a figure which shows the modification of a structure of the static elimination apparatus in this Embodiment. It is a figure which shows the modification of a structure of the static elimination apparatus in this Embodiment.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 according to the present embodiment. FIG. 2 shows the main part of the control system of the image forming apparatus 1 in the present embodiment. An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 transfers the toner images of Y (yellow), M (magenta), C (cyan), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421 (primary transfer). Then, after superposing four color toner images on the intermediate transfer belt 421, the toner images are transferred to the paper S (secondary transfer) to form an image.

  Further, in the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one step. Tandem system is adopted.

  As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, a static elimination device 80, a control unit 100, and the like. A surface potential detector 150 is provided.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms an image on the paper S based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on the document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image states, operation states of functions, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 is based on the input image data, and image forming units 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using colored toners of Y component, M component, C component, and K component. Etc.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and description, common components are denoted by the same reference numerals, and in order to distinguish each, Y, M, C, or K is added to the reference numerals. In FIG. 1, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 has an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. It is a negatively charged organic photoconductor (OPC) in which a generation layer (CTL) and a charge transport layer (CTL) are sequentially stacked. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a material in which a hole transport material (electron donating nitrogen-containing compound) is dispersed in a resin binder (eg, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative polarity. The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 is a two-component developing type developing device, and attaches toner of each color component to the surface of the photosensitive drum 413 to visualize the electrostatic latent image to form a toner image.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer. The drum unit including the photoconductor drum 413 (photoconductor) is provided with a lubricant application device that applies the lubricant, which has been scraped off by the lubricant application brush, to the photoconductor drum 413.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched around a plurality of support rollers 423 in a loop shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the K component primary transfer roller 422 in the belt traveling direction is a drive roller. This makes it easy to keep the traveling speed of the intermediate transfer belt 421 in the primary transfer portion constant. As the driving roller 423A rotates, the intermediate transfer belt 421 travels in the direction of arrow A at a constant speed.

  The intermediate transfer belt 421 is a belt having conductivity and elasticity, and has a high resistance layer having a volume resistivity of 8 to 11 [log Ω · cm] on the surface. The intermediate transfer belt 421 is rotationally driven by a control signal from the control unit 100. Note that the material, thickness, and hardness of the intermediate transfer belt 421 are not limited as long as they have conductivity and elasticity.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face a roller 423B (hereinafter referred to as “backup roller 423B”) disposed on the downstream side of the driving roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photoconductive drum 413 are primarily transferred onto the intermediate transfer belt 421 in sequence. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and an electric charge having a polarity opposite to that of the toner is applied to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422). It is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. Specifically, a toner image is applied by applying a secondary transfer bias to the secondary transfer roller 424 and applying a charge having a polarity opposite to that of the toner to the back side of the paper S (the side in contact with the secondary transfer roller 424). Is electrostatically transferred to the paper S. The sheet S to which the toner image is transferred is conveyed toward the fixing unit 60.

  The belt cleaning device 426 removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. A specific configuration of the belt cleaning device 426 will be described later. Instead of the secondary transfer roller 424, a configuration (so-called belt-type secondary transfer unit) in which a secondary transfer belt is looped around a plurality of support rollers including the secondary transfer roller is adopted. Also good.

  The fixing unit 60 includes an upper fixing unit 60A having a fixing surface side member disposed on the fixing surface (surface on which the toner image is formed) of the paper S, and the back surface (surface opposite to the fixing surface) of the paper S. A lower fixing unit 60B having a rear surface support member to be disposed, a heating source 60C, and the like are provided. When the back surface side support member is pressed against the fixing surface side member, a fixing nip for nipping and transporting the paper S is formed.

  The fixing unit 60 fixes the toner image on the paper S by heating and pressurizing the paper S on which the toner image is secondarily transferred and conveyed at the fixing nip. The fixing unit 60 is disposed in the fixing device F as a fixing unit. The fixing device F may be provided with an air separation unit that separates the sheet S from the fixing surface side member or the back surface side support member by blowing air.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, etc. is stored for each preset type. . The conveyance path unit 53 includes a plurality of conveyance roller pairs such as registration roller pairs 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent one by one from the top and are conveyed to the image forming unit 40 by the conveyance path unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing. In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and the fixing unit 60 performs a fixing process. The sheet S on which the image is formed is discharged to a discharge tray (not shown) provided outside the apparatus by a discharge unit 52 provided with a discharge roller 52a.

  The surface potential detection unit 150 is a surface potential sensor, for example, and is disposed on the downstream side of the fixing unit 60 in the paper transport direction. The surface potential detection unit 150 detects the potential value (surface potential value) on the surface of the paper S on which the toner image is fixed by the fixing unit 60 in a non-contact manner, and outputs the detection signal to the control unit 100.

  The static eliminator 80 is disposed on the downstream side of the surface potential detection unit 150 and the upstream side of the paper discharge unit 52 in the paper conveyance direction. Under the control of the control unit 100, the neutralization device 80 removes charges remaining on the toner image (toner layer) fixed on the paper S by the fixing unit 60 (static elimination).

  Next, a specific configuration of the static elimination device 80 will be described with reference to FIG. The static eliminator 80 includes a droplet formation unit 81, air flow formation units 82 and 83, a droplet supply channel 84, air flow supply channels 85 and 86, a first electrode 87, a voltage application unit 88, and a second electrode 89. I have. The control unit 100 and the static eliminator 80 function as the “static eliminator” of the present invention. The control unit 100 and the charge removal device 80 may be configured as a unit and attached to the image forming apparatus 1, or each may be separately incorporated in the image formation apparatus 1 and function as the “charge removal device” of the present invention. It may be. The first electrode 87, the voltage applying unit 88, and the second electrode 89 function as the “ion forming unit” of the present invention.

  The droplet forming unit 81 forms the droplet 110 from the liquid, and supplies the formed droplet 110 to the discharge space 140 described later via the droplet supply channel 84. In the present embodiment, the droplet forming unit 81 forms and sprays the droplet 110 by applying ultrasonic vibration to the liquid using a vibration element (for example, a piezoelectric element or an ultrasonic transducer). Ultrasonic nebulizer (ultrasonic nebulizer). The droplet forming unit 81 can control the droplet diameter of the droplet 110 by changing the amplitude and the vibration frequency of the vibration element, and is very small (for example, several [μm], 10 [μm] in the present embodiment). The following droplets 110 can be formed.

  The air flow forming unit 82 is an air fan, for example, and sucks air in the image forming apparatus 1 and supplies the sucked air to the discharge space 140 via the air flow supply channel 85 (flow rate: for example, 5 [cc / min]).

  The air flow forming unit 83 sucks air in the image forming apparatus 1 and supplies the sucked air to the discharge space 140 via the air flow supply channel 86 (flow rate: 5 [cc / min, for example]. ]).

  The 1st electrode 87 is a wire electrode, and the voltage application part 88 is connected. The second electrode 89 is a counter electrode disposed to face the first electrode 87 with a predetermined interval. The first electrode 87 and the second electrode 89 are arranged so as to cover the entire surface in the paper width direction orthogonal to the paper transport direction of the paper S. The voltage application unit 88 applies an alternating high-frequency voltage to a pair of opposed electrodes (between the first electrode 87 and the second electrode 89). As a result of high frequency voltage being applied between the first electrode 87 and the second electrode 89 and corona discharge being performed, a discharge space 140 is formed between the first electrode 87 and the second electrode 89. In the discharge space 140, ionized positive polarity ions 120 and radicals 130 activated by electron collision are formed. In the present embodiment, the voltage application unit 88 may apply a DC high frequency voltage, or may apply a DC high frequency voltage superimposed on the AC high frequency voltage. However, from the viewpoint of forming a more stable discharge space 140 by reciprocating electrons, the voltage application unit 88 preferably applies an alternating high-frequency voltage.

  In the present embodiment, since the droplet forming unit 81 can form the minute droplet 110, the discharge performed between the first electrode 87 and the second electrode 89 is inhibited by the droplet 110. Can be prevented. As the droplet diameter of the droplet 110 is smaller, the inhibition to the discharge is reduced, and the formation of the ions 120 and the radicals 130 can be performed stably. If the discharge space 140 can be stably formed, the droplet diameter of the droplet 110 formed by the droplet forming unit 81 and the vibration condition (the amplitude of the vibration element and the vibration element when the droplet 110 is formed). Vibration frequency), a high-frequency voltage applied by the voltage application unit 88, a distance between the first electrode 87 and the second electrode 89, a flow rate and a type of air flow, and the like may be arbitrarily set.

  The ions 120 and the radicals 130 are extracted from the discharge space 140 by the air flow formed by the air flow forming units 82 and 83 and are fixed on the sheet S by the fixing unit 60 (negative charge remains). The surface is supplied (irradiated). When the surface of the toner layer T is supplied with the ions 120 and the radicals 130, the surface energy is increased and the surface becomes hydrophilic. Further, the negative charge remaining on the surface of the toner layer T is removed by supplying the ions 120. In the present embodiment, since the discharge space 140 is not in contact with the paper S, it is possible to prevent the discharge of the toner layer T fixed to the paper S and the occurrence of image defects.

  The droplet 110 supplied to the discharge space 140 by the droplet forming unit 81 passes through the discharge space 140 and is supplied to the surface of the toner layer T fixed on the paper S. The surface of the toner layer T is made hydrophilic by the supply of the ions 120 and the radicals 130, that is, the contact angle of the surface with respect to the droplet 110 is increased, so that the surface of the toner layer T is not made hydrophilic. As a result, the adhesion area of the droplet 110 to the surface is increased. As a result, the surface of the toner layer T is uniformly humidified by the supplied droplets 110. In other words, when the surface of the toner layer T is humidified, it is possible to prevent the occurrence of uneven humidification due to the liquid 110 adhering to the toner layer T gathering. By uniformly humidifying the surface of the toner layer T, the charge removal performance of the ions 120 on the surface of the toner layer T can be maximized.

  Also, some droplets 110 are charged with a positive polarity by the ions 120 in the discharge space 140 when passing through the discharge space 140. By supplying the droplet 110 charged to the positive polarity to the surface of the toner layer T, the negative charge remaining on the surface of the toner layer T is removed.

  As described above, the present embodiment employs a configuration in which the surface of the toner layer T is hydrophilicized, humidified, and neutralized at the same time. Therefore, the static eliminator 80 can be arranged in a short paper conveyance path, that is, the size of the static eliminator 80 can be suppressed, and more specifically, the static elimination of the paper S can be performed at high speed.

  In the present embodiment, the liquid used to form the droplets 110 is preferably alcohol. This is because alcohol is highly hydratable and easily adheres to the surface of the toner layer T that has been made hydrophilic and has high surface energy. Further, alcohol has an effect of cleaning the surface of the toner layer T, and an effect of promoting hydrophilicity by the ions 120 and radicals 130 can be expected.

Next, an evaluation experiment for confirming the effect in the configuration of the above embodiment will be described. In the evaluation experiment, water or alcohol is used as the liquid used to form the droplet 110, and the operation of removing the charge remaining on the toner image fixed on the paper S by the fixing unit 60 is performed on the static eliminator 80. I let them. The state of occurrence of a paper discharge sticking phenomenon (see the background art) when water or alcohol was used as the liquid used to form the droplets 110 was evaluated against the following evaluation criteria. In this evaluation experiment, the high-frequency voltage (alternating current) applied by the voltage application unit 88, its frequency, and the process speed of the image forming apparatus 1 are varied, and images are continuously displayed on 200 sheets of paper S. Forming was performed, and the paper S as a printed output was left on the paper discharge tray for 30 minutes. The flow rate of the air flow supplied to the discharge space 140 by the air flow forming units 82 and 83 is 5 [cc / min].
(Status of occurrence of paper sticking phenomenon)
○: The paper sticking phenomenon did not occur. △: The paper sticking phenomenon occurred, but it was at a level where there was no problem in operation. ×: The discharge space 140 could not be formed, so the paper sticking phenomenon occurred.

Table 1 is a table showing the state of occurrence of the paper discharge sticking phenomenon when water is used as the liquid used to form the droplets 110.

Table 2 is a table showing the state of occurrence of the paper discharge sticking phenomenon when alcohol is used as the liquid used to form the droplets 110.

  As shown in Tables 1 and 2, by using alcohol as the liquid used to form the droplets 110, even if the process speed of the image forming apparatus 1 is increased, a desired charge eliminating function is secured and the paper is pasted. The sticking phenomenon could be prevented.

  As described above in detail, in the present embodiment, the static eliminator 80 includes the ion forming unit (the first electrode 87, the voltage applying unit 88, and the second electrode 89) that forms the ions 120 and the radicals 130, and the liquid from the liquid A droplet forming unit 81 that forms the droplet 110 and air flow forming units 82 and 83 that form an air flow are provided. The control unit 100 supplies the ions 120, the radicals 130, and the droplets 110 to the toner image (toner layer T) formed on the paper S by an air flow so as to supply the ions 120, the radicals 130, and the droplets 110. And controls the air flow forming portions 82 and 83.

  According to the present embodiment configured as described above, the surface of the toner layer T is made hydrophilic by increasing the surface energy by supplying the ions 120 and the radicals 130. Further, the negative charge remaining on the surface of the toner layer T is removed by supplying the ions 120. Further, the surface of the hydrophilic toner layer T is uniformly humidified by supplying the droplets 110. That is, it is possible to prevent humidification unevenness on the surface of the toner layer T. By uniformly humidifying the surface of the toner layer T, the charge removal performance of the ions 120 on the surface of the toner layer T can be maximized. Also, some droplets 110 are charged with a positive polarity by the ions 120 in the discharge space 140 when passing through the discharge space 140. By supplying the droplet 110 charged to the positive polarity to the surface of the toner layer T, the negative charge remaining on the surface of the toner layer T is removed. In this embodiment, since the surface of the toner layer T is hydrophilicized, humidified, and neutralized at the same time, the static eliminator 80 can be disposed in a short sheet conveyance path. The increase in size can be suppressed, and the charge removal of the paper S can be performed at high speed.

  In the above-described embodiment, an AC high frequency voltage is applied to a pair of opposing electrodes (between the first electrode 87 and the second electrode 89), whereby a discharge space 140 is formed between the first electrode 87 and the second electrode 89. However, the electrode configuration is not limited to this as long as the desired discharge space 140 can be formed. For example, as shown in FIG. 4A, a parallel plate electrode may be used as the first electrode 87 instead of the wire electrode. 4B, a parallel plate electrode may be used as the first electrode 87, and a dielectric 90 may be disposed inside the first electrode 87 and the second electrode 89. Further, as shown in FIG. 4C, a comb electrode may be used as the first electrode 87 instead of the wire electrode.

  In the above embodiment, the first electrode 87 and the second electrode 89 are described so as to cover the entire surface of the sheet S in the sheet width direction, but there is no unevenness over the entire surface in the sheet width direction. The arrangement configuration of the first electrode 87 and the second electrode 89 is not limited to this as long as the charge removal can be performed. FIG. 5A is a diagram showing the configuration of the droplet supply channel 84, the first electrode 87, and the second electrode 89. 5B, C, and D are AA cross-sectional views of FIG. 5A. For example, as shown in FIG. 5B, a plurality of droplet supply channels 84, first electrodes 87, and second electrodes 89 may be arranged in the paper width direction. Further, as shown in FIG. 5C, the droplet supply channel 84 is arranged so as to cover the entire surface in the paper width direction, and each of the first electrode 87 and the second electrode 89 is configured to be movable in the paper width direction. Also good. Further, as shown in FIG. 5D, each of the first electrode 87 and the second electrode 89 is disposed so as to cover the entire surface in the paper width direction, and the droplet supply channel 84 is configured to be movable in the paper width direction. Also good.

  In the above-described embodiment, the control unit 100 supplies the ions 120 and the droplets 110 to the toner image based on the image forming condition that is an index of the likelihood of the paper discharge sticking phenomenon. It may be determined whether or not the sheet S is discharged. Specifically, the control unit 100 may acquire the temperature and humidity around the image forming apparatus 1, the paper type of the paper S, the print coverage, and the print mode, and determine whether or not to neutralize the paper S. For example, when the temperature around the image forming apparatus 1 is 23 [° C.], the control unit 100 determines to neutralize the paper S. In addition, when the paper type of the paper S is a coated paper, the control unit 100 determines to neutralize the paper S. Further, the control unit 100 determines to neutralize the paper S when the print coverage is high (for example, 20% or more). In addition, when the printing mode is the double-sided printing mode, the control unit 100 determines to neutralize the paper S. From the same viewpoint, the control unit 100 obtains the secondary transfer current value, and when the secondary transfer current value is high (for example, 100 [μA] or more), the control unit 100 determines to neutralize the sheet S. good. Further, the control unit 100 acquires the potential value on the surface of the paper S on which the toner image is fixed from the surface potential detection unit 150, and when the potential value is high (for example, 500 [V] or more), the paper S It may be determined that the charge is removed.

  In the above embodiment, as shown in FIG. 6, a plurality of paper transport paths 53b and 53c are provided on the downstream side of the fixing unit 60 and the upstream side of the paper discharge unit 52 in the paper transport direction. When the sheet S is neutralized, the sheet S is conveyed to the sheet conveyance path 53c where the neutralization device 80 is arranged. On the other hand, when the sheet S is not neutralized, the sheet S is conveyed to the sheet conveyance path 53b where the neutralization apparatus 80 is not arranged. The sheet conveying unit 50 may be controlled so as to make it happen.

  In the above embodiment, the example in which the droplet 110, the ion 120, and the radical 130 are supplied from the static eliminator 80 to the paper S in the downward direction has been described (see FIG. 1). In addition, the droplet 110 formed by the droplet forming unit 81 may adhere to the wall surface of the droplet supply channel 84, so that the droplet supply channel 84 may be blocked. Therefore, as shown in FIG. 7A, it is preferable to dispose the static eliminating device 80 so that the direction in which the droplets 110, the ions 120, and the radicals 130 are supplied is upward. By disposing the static elimination device 80 in this way, as shown in FIG. 7B, the droplet 110a attached to the wall surface of the droplet supply channel 84 falls in the direction of the arrow under its own weight and is discharged as drainage. It is possible to prevent the droplet supply channel 84 from being blocked by the droplet 110.

  In addition, each of the above-described embodiments is merely an example of actualization in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Image reading part 20 Operation display part 21 Display part 22 Operation part 30 Image processing part 40 Image forming part 50 Paper conveyance part 60 Fixing part 71 Communication part 72 Memory | storage part 80 Static elimination apparatus 81 Droplet formation part 82,83 Air flow forming section 84 Droplet supply flow path 85, 86 Air flow supply flow path 87 First electrode 88 Voltage application section 89 Second electrode 90 Dielectric 100 Control section 101 CPU
102 ROM
103 RAM
110, 110a Droplet 120 Ion 130 Radical 140 Discharge space 150 Surface potential detector S Paper T Toner layer

Claims (7)

An ion forming part for forming ions;
A droplet forming section for forming droplets from a liquid;
An air flow forming part for forming an air flow;
A control unit for controlling the ion forming unit, the droplet forming unit, and the air flow forming unit so as to supply the ions and the droplets by the air flow to a toner image formed on a sheet; ,
A static eliminator comprising: The ion forming unit forms the ions by applying a voltage between a pair of electrodes opposed to each other with a gap and generating a discharge between the electrodes.
The static eliminator according to claim 1. The ion forming part forms a radical,
The control unit controls the ion forming unit, the droplet forming unit, and the air flow forming unit so as to supply the ions, the radicals, and the droplets to the toner image by the air flow. ,
The static elimination apparatus of Claim 1 or 2. The droplet forming unit forms the droplet by applying ultrasonic vibration to the liquid.
The static elimination apparatus of any one of Claims 1-3. The liquid is alcohol;
The static elimination apparatus of any one of Claims 1-4. The control unit determines whether to supply the ions and the droplets to the toner image based on image forming conditions.
The static elimination apparatus of any one of Claims 1-5. A fixing unit for fixing the toner image on the paper;
A paper discharge unit that is provided on the downstream side in the paper transport direction and discharges the paper on which the toner image is fixed;
With
The static eliminator according to claim 1 is provided between the fixing unit and the paper discharge unit.
Image forming apparatus.

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