JP6111894B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in the image forming apparatus, in accordance with the expansion of user needs, etc., a label made by laminating a surface base material via an adhesive layer on a metal foil film or a release paper other than plain paper deposited on the surface of the film. It is required to form images on various recording media such as paper. In addition to the so-called cut paper that is cut into a predetermined size, a continuous continuous paper or the like is used as the recording medium supply form. In such an image forming apparatus, those described in Patent Documents 1 to 4 and the like have already been proposed as a technique related to conveyance of a recording medium such as continuous paper.

  Patent Document 1 discloses a sheet conveying unit that frictionally conveys continuous sheets of paper, an image recording unit that records an image on the sheet, a line sensor that detects the position of a sheet end provided perpendicular to the sheet conveying direction, and a sheet A sheet width direction position correcting means for correcting the position in the sheet width direction by causing a difference in the pressing force in the sheet width direction of the pair of conveying rollers that nip and convey the sheet, and a member that defines a reference position of the sheet edge And a member for releasing the contact of the conveying roller pair of the position correcting means in the paper width direction, and a paper slowing device.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses an image / information recording medium device that transports a recording medium using a roller having a metal core at the center and a conductive elastic body on the surface. It is comprised so that it may be provided.

  Japanese Patent Laid-Open No. 2004-260688 removes static electricity from the roll paper by contacting with the outer peripheral surface of the roll paper, and contacts with a static elimination member that is regulated by the contact member so as to contact the outer peripheral surface of the roll paper by a predetermined amount. A release member for releasing both the contact of the contact member and the contact of the charge removal member is provided so that both the member and the charge removal member are separated from the outer peripheral surface of the roll paper by a predetermined distance at a predetermined timing.

  Patent Document 4 is arranged so as to oppose a conveyance unit that conveys a recording medium and a position through which the recording medium conveyed by the conveyance unit passes, and passes through the opposite position when the conveyance unit starts conveying the recording medium. Discharges ions to remove static electricity from the recording medium to be discharged, and neutralizes the discharge when the conveyance of the recording medium is stopped by the conveying means; and after the discharge of ions is stopped by the neutralizing means, And a discharge unit that discharges ink to the recording medium that has been neutralized.

Japanese Patent Laid-Open No. 10-181969 JP 2000-168191 A JP 2002-348007 A JP 2011-218711 A

  The problem to be solved by the present invention is to provide an image forming apparatus capable of suppressing the occurrence of image quality degradation caused by the resistance of the recording medium being different from that of plain paper.

The invention described in claim 1 is a toner image holding body for holding a toner image;
Transfer means for transferring the toner image held on the toner image holder to a recording medium including at least one of a recording medium having a surface resistance of 10 ⁵ to 10 ⁷ Ω and a recording medium having a surface resistance of 10 ¹⁰ to 10 ¹⁵ Ω ; ,
Obtaining means for obtaining the resistance of the recording medium;
A contact member that contacts the transfer surface of the recording medium on the upstream side in the recording medium conveyance direction of the transfer means;
According to the resistance of the recording medium acquired by the acquisition means, when the surface resistance is a recording medium of 10 ⁵ to 10 ⁷ Ω, a resistance is interposed between the contact member and the ground potential, And a control means for controlling a switching means for switching the contact member to connect to the ground potential when the recording medium has a resistance of 10 ¹⁰ to 10 ¹⁵ Ω. .

According to a second aspect of the present invention, the contact member is electrically connected to a housing of the image forming apparatus,
The image forming apparatus according to claim 1, wherein the control unit adjusts a resistance interposed between a housing of the image forming apparatus and a ground potential.

In the invention described in claim 3, the contact member is connected to a ground potential,
The image forming apparatus according to claim 1, wherein the control unit controls presence or absence of contact between the contact member and the recording medium.

  The invention described in claim 4 further comprises a second contact member that contacts the transfer surface of the recording medium on the downstream side of the transfer unit in the recording medium conveyance direction. 4. The image forming apparatus according to any one of 3 above.

  According to a fifth aspect of the present invention, the recording medium is made of continuous paper, and the control unit includes a resistance interposed between the contact member and a ground potential including a paper feeding unit and a winding unit for the continuous paper. 5. The image forming apparatus according to claim 1, wherein the presence or absence of contact between the contact member and the recording medium is controlled.

  According to the first aspect of the present invention, it is possible to suppress the occurrence of deterioration in image quality due to the resistance of the recording medium being different from that of plain paper as compared with the case where the configuration is not provided.

  According to the second aspect of the present invention, it is possible to suppress deterioration of image quality due to the resistance of the recording medium being different from that of plain paper with a simple configuration as compared with the case where the configuration is not provided.

  According to the third aspect of the present invention, it is possible to avoid that the contact member always comes into contact with the recording medium as compared with the case where the configuration is not provided.

  According to the invention described in claim 4, it is possible to suppress the occurrence of problems caused by the fact that the resistance of the recording medium differs from that of plain paper on the downstream side of the transfer means, compared to the case where the configuration is not provided. it can.

  According to the invention described in claim 5, there is a problem caused by the fact that the resistance of the recording medium including the continuous paper feeding unit and the winding unit is different from that of plain paper as compared with the case without the configuration. Generation | occurrence | production can be suppressed.

1 is a schematic configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. 1 is a configuration diagram showing a main part of an image forming apparatus according to Embodiment 1 of the present invention. It is a schematic diagram which shows a recording medium. It is a schematic diagram which shows the mechanism which detects resistance of a recording medium. It is a circuit diagram which shows a means to switch resistance of a static elimination member. 1 is a block diagram showing a control circuit of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a configuration diagram illustrating a resistance switching unit interposed between a housing of the image forming apparatus and a ground potential. It is a schematic diagram which shows the contact-separation mechanism of the static elimination member of the image forming apparatus which concerns on Embodiment 2 of this invention. It is a schematic block diagram which shows the image forming apparatus which concerns on Embodiment 3 of this invention. It is a graph which shows the result of an Example. It is a graph which shows the result of an Example.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
1 and 2 show an image forming apparatus according to the first embodiment. FIG. 1 shows an outline of the entire image forming apparatus, and FIG. 2 shows an enlarged main part (image forming apparatus, etc.) in the image forming apparatus.

<Overall Configuration of Image Forming Apparatus>
The image forming apparatus 1 according to the first embodiment is configured as a color printer, for example. The image forming apparatus 1 holds a plurality of image forming apparatuses 10 as image forming means for forming toner images developed with toner constituting the developer 4 and toner images formed by the respective image forming apparatuses 10. Then, an intermediate transfer device 20 that finally transports to a secondary transfer position for secondary transfer to a recording paper 5 as an example of a recording medium, and a required recording paper 5 to be supplied to the secondary transfer position of the intermediate transfer device 20 A sheet feeding device 50 that accommodates and conveys the toner, and a fixing device 40 that fixes the toner image on the recording paper 5 secondarily transferred by the intermediate transfer device 20.

  For example, the image forming apparatus 1 can be configured as a color copying machine when an image input device 60 for inputting a document image to be formed on the recording paper 5 is additionally provided. In the figure, reference numeral 1a denotes a housing of the image forming apparatus, and the housing 1a is formed of a support structure member made of a conductor, an exterior cover, and the like. Also, the alternate long and short dash line in the figure indicates the main transport path through which the recording paper 5 is transported in the housing 1a.

<Configuration of Main Part of Image Forming Apparatus>
The image forming apparatus 10 exclusively forms four color toner images of yellow (Y), magenta (M), cyan (C), and black (K) and two types of toner images of special colors S1 and S2. It is composed of six image forming apparatuses 10S1, 10Y, 10M, 10C, 10K, and 10S2. The six image forming devices 10 (S1, Y, M, C, K, S2) are arranged in a line in the internal space of the housing 1a. As the developer 4 (S1, S2) of the special color (S1, S2), for example, those composed of color materials that are difficult or impossible to express with the above four colors are used. Is a toner other than the above four colors, a toner that is the same color as the above four toners and has a different saturation, a white toner that forms an underlayer, a transparent toner that improves glossiness, and a foaming property for braille Toner, fluorescent color toner, and the like. In this embodiment, transparent toner is used as the special color toner S1, and white toner is used as the special color toner S2. In addition, the image forming apparatuses 10 (S1, Y, M, C, K, S2) have substantially the same configuration as described below except that the types of developers to be handled are different. In this embodiment, the image forming device 10S1 using the transparent toner is disposed on the most upstream side, and the white toner is disposed on the most downstream side. The reason is that white toner may be used as an underlayer on the recording medium side in order to improve the color developability of an image made of color toner.

  Each image forming apparatus 10 (S1, Y, M, C, K, S2) includes a rotating photosensitive drum 11 as shown in FIG. 1 and FIG. The following devices are mainly arranged. The main devices are a charging device 12 that charges a peripheral surface (image holding surface) on the photosensitive drum 11 on which an image can be formed to a required potential, and image information (on the charged peripheral surface of the photosensitive drum 11). The exposure device 13 that irradiates the light LB based on the signal) to form an electrostatic latent image (for each color) having a potential difference, and the corresponding color (S1, Y, M, C, K, A developing device 14 (S 1, Y, M, C, K, S 2) that develops with the toner of the developer 4 in S 2) to form a toner image, and a primary transfer device 15 that transfers each toner image to the intermediate transfer device 20. And a pre-cleaning charging device 16 for charging toner and other deposits remaining on the image holding surface of the photosensitive drum 11 after the primary transfer, and a drum cleaning device 17 for removing the recharged deposits for cleaning. , Neutralizing the image holding surface after cleaning the photosensitive drum 11 18 is like.

  The photosensitive drum 11 is formed by forming an image holding surface having a photoconductive layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a cylindrical or columnar base material to be grounded. The photosensitive drum 11 is supported so as to rotate in a direction indicated by an arrow A when power is transmitted from a rotation driving device (not shown).

  The charging device 12 is configured by a non-contact type charging device such as a corona discharger that is disposed without being in contact with the photosensitive drum 11. The charging device 12 is supplied with a charging voltage to the discharge member. As the charging voltage, when the developing device 14 performs reversal development, a voltage or current having the same polarity as the charging polarity of the toner supplied from the developing device 14 is supplied.

  The exposure device 13 irradiates light (dotted line with arrows) LB configured according to image information input to the image forming apparatus 1 onto the peripheral surface of the photosensitive drum 11 after being charged. It forms an electrostatic latent image. When the latent image is formed, image information (signal) input to the image forming apparatus 1 by any means is transmitted to the exposure apparatus 13.

  As shown in FIG. 2, each of the developing devices 14 (S1, Y, M, C, K, S2) is provided with a developer in a housing 140 in which an opening and a storage chamber for the developer 4 are formed. 2, two developing rolls 141 and 142 that respectively transport the developer 4 to two development areas facing the photosensitive drum 11, and two screw augers that transport the developer 4 so as to pass through the developing roll 142 while stirring. And a layer thickness regulating member 145 for regulating the amount (layer thickness) of the developer held on the developing roll 142, and the like. A developing voltage is supplied to the developing device 14 between the developing rolls 141 and 142 and the photosensitive drum 11 from a power supply device (not shown). Further, the developing rolls 141 and 142 and the agitating / conveying members 143 and 144 are rotated in a required direction by receiving power from a rotation driving device (not shown). Further, as the four color developers 4 (Y, M, C, K) and the two special color developers 4 (S1, S2), a two-component developer containing a non-magnetic toner and a magnetic carrier is used. Is done.

  The primary transfer device 15 is a contact-type transfer device including a primary transfer roll that rotates in contact with the peripheral surface of the photosensitive drum 11 and is supplied with a primary transfer voltage. As the primary transfer voltage, a DC voltage having a polarity opposite to the charging polarity of the toner is supplied from a power supply device (not shown).

  As shown in FIG. 2, the drum cleaning device 17 is disposed so as to be in contact with the peripheral surface of the photosensitive drum 11 after the primary transfer and the peripheral surface of the photosensitive drum 11 after the primary transfer at a required pressure. A cleaning plate 171 for removing adhering matter such as toner and cleaning, and a rotating brush roll disposed so as to rotate in contact with the circumferential surface of the photosensitive drum 11 at the upstream side of the cleaning plate 171 in the rotational direction of the photosensitive drum 11 172, and a sending member 173 such as a screw auger for collecting and adhering the adhering matter such as toner removed by the cleaning plate 171 and sending it to a collecting system (not shown). As the cleaning plate 171, a plate-like member (for example, a blade) made of a material such as rubber is used.

  As shown in FIG. 1, the intermediate transfer device 20 is disposed so as to exist at a position below each image forming device 10 (S1, Y, M, C, K, S2). The intermediate transfer device 20 is an intermediate transfer belt 21 as an image carrier belt that rotates in the direction indicated by an arrow B while passing through a primary transfer position between the photosensitive drum 11 and the primary transfer device 15 (primary transfer roll). A plurality of belt support rolls 22 to 27 that hold the intermediate transfer belt 21 in a desired state from the inner surface thereof and rotatably support the outer peripheral surface (image) of the intermediate transfer belt 21 supported by the belt support roll 26. A secondary transfer device 30 disposed on the holding surface) side for secondary transfer of the toner image on the intermediate transfer belt 21 to the recording paper 5, and remains on the outer peripheral surface of the intermediate transfer belt 21 after passing through the secondary transfer device 30. The belt cleaning device 28 mainly removes the adhering matter such as toner and paper dust adhering thereto.

  As the intermediate transfer belt 21, for example, an endless belt made of a material in which a resistance adjusting agent such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin is used. The belt support roll 22 is configured as a drive roll, the belt support rolls 23, 25, and 27 are configured as driven rolls that hold the travel position of the intermediate transfer belt 21, and the belt support roll 24 is configured as a tension applying roll. The belt support roll 26 is configured as a secondary transfer backup roll.

  As shown in FIG. 1, the secondary transfer device 30 has a surface of the intermediate transfer belt 21 at a secondary transfer position that is an outer peripheral surface portion of the intermediate transfer belt 31 supported by the belt support roll 26 in the intermediate transfer device 20. A secondary transfer apparatus of a contact type comprising a secondary transfer roll in contact with the substrate. Further, a DC voltage having a polarity opposite or the same as the charging polarity of the toner is supplied as a secondary transfer voltage to the secondary transfer roll 30 or the support roll 26 of the intermediate transfer device 20. In the present embodiment, in addition to supplying a DC voltage, an AC voltage may be superimposed on the DC voltage and supplied.

  The fixing device 40 is heated by a heating unit so as to rotate in a direction indicated by an arrow and to keep a surface temperature at a predetermined temperature inside a casing 41 in which an inlet and an outlet for the recording paper 5 are formed. A heating rotator 42 provided with a fixing belt, and a drum-type pressurizing rotator 43 that rotates in contact with the heating rotator 42 in a state substantially along the axial direction of the heating rotator 42 are arranged. Is. In the fixing device 40, the contact portion where the heating rotator 42 and the pressing rotator 43 come into contact becomes a fixing processing unit that performs a required fixing process (heating and pressing).

  The paper feeding device 50 is disposed so as to exist at a position below the intermediate transfer device 20 and the secondary transfer device 30. The paper feeding device 50 includes a plurality (or a single) of paper storage bodies 51 for storing recording papers 5 of a desired size and type, and sending out the recording paper 5 from the paper storage bodies 51 one by one. The apparatus 52 is mainly configured. The paper container 51 is attached, for example, so that it can be pulled out to the front surface (side surface that the user faces during operation) of the housing 1a.

  Between the paper feeding device 50 and the secondary transfer device 30, a plurality of paper conveyance roll pairs 53 to 57 for conveying the recording paper 5 delivered from the paper feeding device 50 to the secondary transfer position and a conveyance guide material (not shown). A sheet feeding / conveying device 58 is provided as a configured conveying means. A pair of paper transport rollers 57 disposed at a position immediately before the secondary transfer position in the paper feed transport device 58 adjusts the transport timing of the recording paper 5, for example, so that the recording paper eventually reaches the secondary transfer position. 5 is configured as a roll (registration roll) for adjusting the position 5. Further, between the secondary transfer device 30 and the fixing device 40, a pair of paper transport rollers 58a and a belt form for transporting the recording paper 5 after the secondary transfer sent out from the secondary transfer device 30 to the fixing device 40. A paper conveyance device 58b is provided. Further, a sheet discharge roll pair 59 for discharging the fixed recording sheet 5 fed from the fixing device 40 to the outside of the casing 1a is provided in a portion near the sheet discharge port formed in the casing 1a. ing.

  The image forming apparatus 1 can form images on both sides of the recording paper 5. The image forming apparatus 1 reverses the front and back of the recording paper 5 on which the image is formed on the front surface (first surface), and again conveys the paper to the secondary transfer position of the intermediate transfer belt 21. It has. On the downstream side of the fixing device 40, a conveyance path switching unit 91 that switches the conveyance path of the recording paper 5 between the paper discharge roll pair 59 side and the double-sided paper conveyance device 90 side is disposed. The double-sided paper conveyance device 90 includes a paper reversing unit 92 that reverses the front and back of the recording paper 5 that has been subjected to fixing processing on the front surface (first surface) by the fixing device 40, and the back surface of the recording paper 5 that has been reversed. A pair of conveyance rolls 93 to 98 for conveying the (second surface) again so as to reach the secondary transfer position of the intermediate transfer belt 12 of the intermediate transfer device 20 and a conveyance guide (not shown) are provided. It is connected to a paper transport device 58.

  Further, a manual sheet feeder 80 is provided on one side surface of the housing 1a. The manual sheet feeding device 80 is mainly configured by a stacking base 81 on which recording papers 5 of a desired size and type are stacked and a sending-out device 82 for feeding the recording papers 5 one by one from the stacking base 81. ing.

  The image input device 60 provided in the case of configuring as the above-described color copying machine is an image reading device that reads an image of a document having image information to be printed. For example, as shown in FIG. Arranged at the top of la. This image input device 60 illuminates while moving a document placing plate (platen glass) 61 made of a transparent glass plate or the like on which a document 6 having image information to be read is placed, and a document 6 placed on the document placing plate 61. A light source 62 that moves along with the light source 62, receives the reflected light from the document 6 and reflects it in a predetermined direction, and moves at a predetermined speed and a predetermined distance with respect to the reflective mirror 63. The first reflection mirror 64 and the second reflection mirror 65, the image reading element 66 composed of a CCD or the like that receives and reads the reflected light from the document 6 and converts it into an electrical signal, and forms an image of the reflected light on the image reading element 66. It is mainly composed of an imaging lens 67 and the like. A reference numeral 68 in FIG. 1 is an open / close cover that closes the document placing plate 61.

  Further, the image information of the document read and input by the image input device 60 is subjected to necessary image processing by the image processing device 70. First, in the image input device 60, the image information of the read original is converted into, for example, red (R), green (G), and blue (B) image data (for example, 8-bit data) to the image processing device 70. Send. On the other hand, the image processing device 70 performs predetermined image processing such as shading correction, misregistration correction, brightness / color space conversion, gamma correction, bordering, color / movement editing, and the like on the image data transmitted from the image input device 60. Apply processing. Further, the image processing apparatus 70 changes the image signal subjected to the image processing to each of the four color (Y, M, C, K) image signals, and then transmits them to the exposure apparatus 13. The image processing device 40 also generates image signals for the two special colors (S1, S2).

<Operation of Entire and Main Parts of Image Forming Apparatus>
Hereinafter, a basic image forming operation by the image forming apparatus 1 will be described.

  Here, first, a full-color image constituted by combining toner images of four colors (Y, M, C, K) using the four image forming devices 10 (Y, M, C, K). The image forming operation at the time of forming will be described as a representative.

  When the image forming apparatus 1 receives command information for requesting an image forming operation (printing), the four image forming apparatuses 10 (Y, M, C, K), the intermediate transfer apparatus 20, the secondary transfer apparatus 30, and the fixing apparatus. 40 etc. starts.

  In each image forming device 10 (Y, M, C, K), each photoconductor drum 11 is first rotated in the direction indicated by an arrow A, and each charging device 12 makes a required surface of each photoconductor drum 11 on the surface. Each is charged to a polarity (negative polarity in the first embodiment) and a potential. Subsequently, the exposure apparatus 13 converts the image information input to the image forming apparatus 1 into each color component (Y, M, C, K) with respect to the surface of the photosensitive drum 11 after charging. The light LB emitted based on this signal is irradiated, and an electrostatic latent image of each color component composed of a required potential difference is formed on the surface thereof.

  Subsequently, each developing device 14 (Y, M, C, K) has a corresponding color charged with a required polarity (minus polarity) with respect to the electrostatic latent image of each color component formed on the photosensitive drum 11. (Y, M, C, K) toner is supplied from developing rolls 141 and 142, respectively, and electrostatically attached to perform development. By this development, the electrostatic latent images of the respective color components formed on the respective photosensitive drums 11 are visualized as toner images of four colors (Y, M, C, K) respectively developed with the corresponding color toners. It becomes.

  Subsequently, when each color toner image formed on the photosensitive drum 11 of each image forming device 10 (Y, M, C, K) is conveyed to the primary transfer position, the primary transfer device 15 causes each color image. The toner image is primarily transferred in such a manner that the toner image is sequentially superimposed on the intermediate transfer belt 21 rotating in the direction indicated by the arrow B of the intermediate transfer device 20.

  Further, in each image forming apparatus 10 in which the primary transfer has been completed, after the pre-cleaning charging device 16 recharges the adhering matter such as toner remaining on the surface of the photosensitive drum 11 after the primary transfer, the drum cleaning device 17 is restarted. The charged deposits are removed so as to be scraped off to clean the surface of the photosensitive drum 11, and finally the static eliminator 18 neutralizes the surface of the photosensitive drum 11 after cleaning. Thereby, each image forming apparatus 10 is brought into a state in which the next image forming operation can be performed.

  Subsequently, in the intermediate transfer device 20, the toner image primarily transferred by the rotation of the intermediate transfer belt 21 is held and conveyed to the secondary transfer position. On the other hand, the paper feeding device 50 sends the required recording paper 5 to the paper feeding / conveying device 58 in accordance with the image forming operation. In the paper feeding / conveying device 58, a pair of paper conveying rolls 57 serving as registration rolls feeds the recording paper 5 to the secondary transfer position in accordance with the transfer timing.

  At the secondary transfer position, the secondary transfer device 30 collectively transfers the toner image on the intermediate transfer belt 21 onto the recording paper 5. In addition, in the intermediate transfer device 20 that has finished the secondary transfer, the belt cleaning device 28 removes and removes deposits such as toner remaining on the surface of the intermediate transfer belt 21 after the secondary transfer.

  Subsequently, the recording paper 5 onto which the toner image has been secondarily transferred is peeled from the intermediate transfer belt 21 and the secondary transfer roll 30 and then conveyed to the fixing device 40 by the conveying device 58. In the fixing device 40, necessary recording processing (heating and pressing) is performed by introducing the recording paper 5 after the secondary transfer through the contact portion between the rotating heating rotating body 42 and the pressing rotating body 43. ) To fix the unfixed toner image on the paper 5. Finally, the recording paper 5 after the fixing is completed is set, for example, outside the casing 1a by the paper discharge roll pair 59 in the image forming operation only for forming an image on one side thereof. Not discharged to the discharge container.

  Through the above operation, the recording paper 5 on which a full color image formed by combining four color toner images is output.

  Next, the operation when the image forming apparatus 1 forms a special color toner image composed of the developer of the special colors S1 and S2 when performing the normal image formation described above, for example, will be described.

  In this case, first, in the image forming apparatuses 10S1 and 10S2, the same image forming operation as that of the image forming apparatus 10 (Y, M, C, K) described above is performed. Special color toner images (S1, S2) are formed on the photosensitive drum 11, respectively. Subsequently, the special color toner images formed by the image forming devices 10S1 and 10S2 are primarily transferred to the intermediate transfer belt 21 of the intermediate transfer device 20 in the same manner as the image forming operation related to the four color toner images described above. After that, the secondary transfer device 30 performs secondary transfer from the intermediate transfer belt 21 to the recording paper 5 (along with toner images of other colors). Finally, the recording paper 5 on which the special color toner image and the other color toner image are secondarily transferred is subjected to a fixing process in the fixing device 40 and then discharged to the outside of the housing 1a.

  Through the above operation, the recording paper 5 formed so that the two special color toner images are overlapped on the entire surface or a part of the full color image formed by combining the above-described four color toner images is output. The

  In addition, when the image forming apparatus 1 is a color copying machine equipped with the image input device 60, the basic image forming operation is performed as follows.

  That is, in this case, when the document 6 is set in the image input device 60 and the command information for the request for the image forming operation (copy) is received, the image input device 60 reads the document image of the document 6 and then The information of the read original image is subjected to the above-described image processing in the image processing device 70 and is generated as an image signal. Thereafter, the image signal is transmitted to each image forming device 10 (S1, Y, M, C, K, S2) is transmitted to the exposure apparatus 13. As a result, each image forming device 10 performs electrostatic latent image formation and toner image formation based on the image information of the document 6. Thereafter, the same operation as in the case of the image forming operation (printing) described above is performed, and finally an image composed of the toner image is formed on the recording paper 5 and output.

<Configuration of Characteristic Parts of Recording Medium and Image Forming Apparatus>
As the recording medium 5 used in the image forming apparatus 1, for example, as shown in FIG. 3 (a), silver is formed on the surface of a release paper 5a as a film-like mount made of a synthetic resin such as PET (polyethylene terephthalate). A silver foil film on which a metal foil 5b made of metal such as aluminum is vapor-deposited, or a film-like release paper 5a made of synthetic resin such as PET (polyethylene terephthalate) as shown in FIG. The film label etc. which laminated | stacked the surface base material 5d which consists of synthetic resins via the adhesion layer 5c which consists of adhesive materials, such as these, are used. Further, the recording medium 5 may be supplied as continuous paper that is continuous in a long length, in addition to being supplied as cut paper that has been cut into a predetermined size.

The recording medium 5 made of a silver foil film has, on the surface, for example, a resin layer such as polyester or acrylic formed from the viewpoint of strength, resistance, and adhesion, and a layer made of a metal foil 5b is formed below the layer. The surface resistance is about 10 ⁵ to 10 ⁷ Ω, which is significantly lower than the surface resistance of plain paper of about 10 ⁸ to 10 ¹² Ω. On the other hand, the recording medium 5 made of a film label has a surface base material 5d made of a synthetic resin on the surface, and the surface resistance is about 10 ¹⁰ Ω to ^{10 15} Ω, and the surface resistance of plain paper is 10 ⁸ to 10. Compared to about ¹² Ω, the value is significantly higher.

  Therefore, when an image is formed on the recording medium 5 made of a silver foil film, the silver foil film 5 passes through the secondary transfer position T2 where the secondary transfer roll 30 and the intermediate transfer belt 21 are in contact with each other. When the rear end of 5 comes into contact with a conductor such as a frame of the housing 1a existing on the upstream side of the secondary transfer position, a transfer current leaks through the metal foil 5b on the surface of the silver foil film 5 and transfer failure May occur.

  Further, when the recording medium is a recording medium 5 having a high resistance such as a film label, the recording medium 5 is charged by peeling or friction when the recording medium 5 is fed from the paper storage container 51 or the manual paper feeder 70. In addition, electric charge is generated (charged) on the surface of the film label 5, which causes a decrease in transferability of the toner image when the toner image is secondarily transferred from the intermediate transfer belt 21. Furthermore, dust, dust, and the like are likely to electrostatically adhere to the surface of the charged film label 5.

  Therefore, in this embodiment, an acquisition unit that acquires the resistance (surface resistance) of the recording medium 5 is provided. As a specific configuration of the acquisition means, as shown in FIG. 4, a pair of rolls 31 and 32 that are in contact with the surface of the recording medium 5 are arranged, and a constant voltage is applied between the pair of rolls 31 and 32. By detecting the current that sometimes flows between the rolls 31 and 32, the resistance of the recording medium 5 can be directly detected and acquired.

  However, the surface resistance of the recording medium 5 is unique to the recording medium 5, and if the type of the recording medium 5 is known, the resistance of the recording medium 5 can be acquired indirectly. Therefore, in this embodiment, the resistance of the recording medium 5 is obtained indirectly by determining the type of the recording medium 5.

  In this embodiment, as shown in FIG. 1, the brush-shaped first and second contact members made of a conductor that contacts the surface of the recording medium 5 on the upstream side and the downstream side of the secondary transfer position T2 are used. Second neutralization members 85 and 86 are provided. The first and second slow current members 85 and 86 are configured by bundling conductive fibers made of synthetic resin and fine metal wires in a brush shape, and are arranged so as to contact over the entire width of the recording medium 5. ing. The installation position of the first static elimination member 85 is set, for example, on the upstream side of the pair of paper transporting rolls 54 that is upstream of the secondary transfer position T2. The installation position of the second charge removal member 86 is set, for example, on the downstream side of the sheet discharge roll pair 59.

Furthermore, in this embodiment, as shown in FIG. 5, the first and second slow current members 85, 86 are connected to the ground potential (ground) via the resistor R by the switching means 87, or It is configured to be directly connected to the ground potential (earth) or switchable. The resistance value of the resistor R is set to a value of about 10 ⁹ Ω, for example. Further, the resistor R and the switching means 87 may be interposed between the first and second grading members 85 and 86 and the ground potential, for example, the first and second grading members 85 and 86, It is disposed between the housing 1 a of the image forming apparatus 1 located in the vicinity of the slow current members 85 and 86. The housing 1a of the image forming apparatus 1 is connected to a ground potential (ground) by a normal means.

  FIG. 6 is a block diagram showing a control unit of the image forming apparatus according to this embodiment.

  In FIG. 6, reference numeral 100 denotes a control unit composed of electronic components such as a CPU and a memory, and refers to parameters stored in a RAM (not shown) based on a program stored in a ROM (not shown). Overall control of forming operations. The control unit 100 also functions as a control unit that controls the switching operation of the switching unit 87. Further, the control unit 100 acquires the resistance of the recording medium according to the type of the recording medium 5 designated from the control panel 101 described later, and controls the switching of the switching unit 87 according to the resistance of the recording medium 5.

  Reference numeral 101 denotes a control panel of the image forming apparatus 1, and the control panel 101 serves as a display unit for displaying an operation menu, a warning, a message, and the like to the user as shown in FIG. A touch panel 102 that accepts various settings for the menu and a plurality of operation buttons 103 are provided. The touch panel 102 includes designation buttons 104a and 104b for the user to designate a silver foil film or a film label instead of plain paper as the recording paper 5.

<Operation of Characteristic Part of Image Forming Apparatus>
In this embodiment, as shown in FIG. 1, with the start of the image forming operation, the recording medium 5 is fed from the paper feeding device 50 at a predetermined timing, and the fed recording medium 5 is Then, the paper is transported to the secondary transfer position of the intermediate transfer device 20 by the paper feed transport device 58.

  As the recording medium 5, as shown in FIGS. 3A and 3B, there is a case where a recording medium 5 having a resistance significantly different from that of plain paper, such as a metal foil film or a film label, may be used in addition to plain paper. When starting the image forming operation, the user operates the designation buttons 104a and 104b of the control panel 101 to select plain paper, a metal foil film, a film label, or the like as the recording medium 5 on which an image is printed.

  The control unit 100 determines the type of the selected recording medium 5, and when a metal foil film is selected as the recording medium 5, determines that the recording medium has a lower resistance than plain paper, and FIG. As shown, the switching means 87 is switched to the resistance R side, and the resistance R is interposed between the first and second static elimination members 85 and 86 and the ground potential.

Since the metal foil film 5 has a low resistance of 10 ⁶ Ω, the secondary transfer voltage leaks when the metal foil film 5 comes into contact with another member when the metal foil film 5 passes the secondary transfer position T2. Transfer defects may occur.

  In this embodiment, as shown in FIG. 1, since the first static elimination member 85 having a resistance R interposed between the paper feeding and conveying device 58 and the ground potential is disposed, the metal foil film 5 Even when the surface contacts the first charge removal member 85, the transfer voltage is prevented from leaking. As a result, the toner image is satisfactorily secondary transferred from the intermediate transfer belt 21 to the surface of the metal foil film 5 at the secondary transfer position T2, and deterioration of image quality is prevented or suppressed.

  Further, the metal foil film to which the toner image has been transferred at the secondary transfer position T2 is conveyed to the fixing device 40 by the conveying device 58, and the toner image is fixed on the surface. It is discharged to a discharge container (not shown) provided outside the housing 1a.

  On the other hand, the control unit 100 determines the type of the recording medium 5 selected by the user operating the control panel 101, and when the film label is selected as the recording medium 5, the resistance is higher than that of plain paper. As shown in FIG. 5, the switching means 87 is switched to the ground potential side, and the first and second static elimination members 85 and 86 are connected to the ground potential. The static elimination members 85 and 86 may be connected to the ground potential, and as another aspect, may be connected to the ground potential via the casing 1a of the image forming apparatus 1.

Since the film label has a high resistance of 10 ¹⁵ Ω, it tends to be triboelectrically charged when peeled or conveyed when fed from the paper container 51 or the manual paper feeder 81, and has a property that the surface is easily charged. doing.

  In this embodiment, as shown in FIG. 1, since the first static elimination member 85 connected to the paper feeding / conveying device 58 by switching to the ground potential is arranged, the surface of the film label 5 is The charge is removed by the charge eliminating member 85 of 1 and the surface charge is removed. As a result, it is avoided that dust and dirt such as paper dust and toner in the housing 1a of the image forming apparatus 1 are electrostatically attached to the surface of the film label 5 during its conveyance. Further, the toner image is satisfactorily transferred from the intermediate transfer belt 21 to the surface of the film label 5 at the secondary transfer position T2, thereby preventing transfer failure.

  Further, the film label 5 to which the toner image has been transferred at the secondary transfer position T2 is conveyed to the fixing device 40 by the conveying device 58 and fixed on the surface, and then the sheet discharge roll 59 is used for the image forming apparatus. It is discharged to a discharge container (not shown) provided outside the housing 1a.

  At this time, since the second static elimination member 86 is arranged on the downstream side of the paper discharge roll 59, even when the film label is charged by the secondary transfer portion T2, the static elimination is performed by the second static elimination member 86, Dust and dust such as paper dust and toner are discharged outside the image forming apparatus 1 without electrostatically adhering.

  In the first embodiment, the case where the resistor R and the switching unit 87 are disposed between the first and second static elimination members 85 and 86 and the housing 1a of the image forming apparatus 1 has been described. As shown, the resistor R and the switching unit 87 may be arranged between the casing 1a of the image forming apparatus 1 and the ground potential. In this case, only one resistor R and switching means 87 are required, and the configuration can be simplified.

[Embodiment 2]
FIG. 8 shows an image forming apparatus according to the second embodiment.

  In the second embodiment, the first and second charge removal members 85 and 86 are connected to the ground potential, and the first and second charge removal members 85 and 86 are driven with respect to the recording medium 5 by a solenoid, a motor, or the like. It is arranged so that it can be contacted or separated by means. The first and second static elimination members 85 and 86 are supported, for example, so as to be rotatable about a shaft provided at a base end portion thereof, and an arm member disposed so as to cross the shaft is used as a solenoid or the like. By being moved by the driving means, the recording medium can be contacted or separated. The first and second charge removal members 85 and 86 are always connected to the ground potential directly or via the housing 1a of the image forming apparatus 1.

  In this embodiment, it is configured that the type of the recording medium 5 is designated by the user operating the control panel 101, and the control unit 100 responds to the type of the recording medium 5 designated by the user. The first and second charge removal members 85 and 86 are controlled to contact with or separate from the recording medium 5.

  When the control unit 100 determines that the recording medium is a silver foil film, the control unit 100 performs control so that the first and second charge removal members 85 and 86 are separated from the recording medium 5. In addition, when the control unit 100 determines that the recording medium is a film label, the control unit 100 performs control so that the first and second charge removal members 85 and 86 are brought into contact with the recording medium 5.

  Thus, in the second embodiment, according to the type (surface resistance) of the recording medium 5, the first and second static elimination members 85 and 86 connected to the ground potential are brought into contact with the recording medium 5. Alternatively, by controlling the separation, it is possible to suppress or prevent the occurrence of transfer failure with respect to the silver foil film or transfer failure due to charging of the film label.

[Embodiment 3]
FIG. 9 shows an image forming apparatus according to the third embodiment.

  In the third embodiment, a continuous paper is used instead of a standard size such as A3 size or A4 size as a recording medium. The continuous paper itself is made of a metal foil film or a film label as shown in FIG.

  As shown in FIG. 9, a paper feed unit 88 that supplies continuous paper 5 is provided on one side of the housing 1 a of the image forming apparatus 1, and the continuous paper 5 is rolled into the paper feed unit 88. The roll paper wound around is rotatably arranged by a driving means (not shown). The continuous paper 8 fed from the paper feed unit 88 is transported to the inside of the housing 1a of the image forming apparatus 1 by the manual paper feed device 80, and is fed to the secondary transfer position T2 via the paper feed transport device 58. Paper is transported. The continuous paper on which the toner image is secondarily transferred from the intermediate transfer belt 21 is conveyed to the fixing device 40 and subjected to fixing processing, and then discharged to the outside of the casing 1 a of the image forming apparatus 1 by the paper discharge roll pair 59. Is done.

  As shown in FIG. 9, the other side of the housing 1a of the image forming apparatus 1 includes a winding unit 89 that winds the continuous paper 5. The winding unit 89 is a continuous paper on which an image is formed. It is rotatably arranged by a driving means (not shown) so as to write 5 in a roll shape.

  Since the continuous paper 5 is literally a continuous recording medium, the resistance of all the conveyance paths from the paper feeding unit 88 to the winding unit 89 is controlled so that no leakage or the like occurs. There is a need.

  Further, in the case of a film label having high resistance, the surface is charged due to peeling or transfer from the roll paper or friction in the transport path unless the first and second neutralization members 85 and 86 are neutralized, and dust on the surface. Adhesion and winding failure may occur. Furthermore, there is a possibility that a transfer failure due to the charged film label occurs at the secondary transfer position.

  Therefore, in the third embodiment, the first neutralization member 85 and the second neutralization member 86 are configured to control the resistance of all the conveyance paths from the paper feeding unit 88 to the winding unit 89.

[Example]
In order to confirm the effect of the image forming apparatus according to the present embodiment, the present inventors performed an evaluation using a color printer manufactured by Fuji Xerox Co., Ltd .: Apeos Port IV6680.

As the recording medium 5, a silver foil film “S gloss PZ2” manufactured by Lintec Corporation; the basis weight of the release paper is 97 g / m ² , the basis weight of the surface substrate is 93 g / m ² , and the total basis weight is 190 g / m ^2. m ² , a surface resistance of 1.0 × 10 ⁶ Ω, and a film label “PET50 (A) PAT1” also manufactured by Lintec; the basis weight of the release paper is 184 g / m ² and the basis weight of the surface substrate is a 90 g / m ^2, the basis weight of the total 274 g / m ^2, the surface resistance was used as a 1.7 × 10 ¹⁴ Ω.

  As shown in FIG. 1, the image forming apparatus 1 contacts the surface of the recording medium 5 with the first slow brush 85 on the upstream side of the sheet conveying roll 54, which is the upstream side of the secondary transfer position. Arranged to be separable. Further, a second gradual brush 86 is disposed on the downstream side of the sheet discharge roll pair 59 so as to be able to come into contact with and separate from the surface of the recording medium 5.

Further, the housing 1a of the image forming apparatus 1 is configured to be able to switch between a resistance of 10 ⁹ Ω between the ground potential and whether it is directly connected to the ground potential.

  FIG. 10 is a chart showing the results of the above example.

[Example 1]
In the image forming apparatus shown in FIG. 1, a film label having a surface resistance of 10 ¹⁵ Ω is used as a continuous recording medium, and the first and second charge eliminating members 85 and 86 connected to the ground potential are brought into contact with the film label 5. Arranged. As a result, there was no transfer failure when the recording medium had a high resistance and no transfer leak when the recording medium had a low resistance.

[Example 2]
In the image forming apparatus in Example 1, a silver foil film having a surface resistance of 10 ⁶ Ω is used as a recording medium, and the first and second charge eliminating members 85 and 86 connected to the ground potential through the resistor R are in contact with the silver foil film. Evaluation similar to Example 1 was performed except having made it the state made into. As in Example 1, no transfer failure or transfer leak was observed.

[Example 3]
In the image forming apparatus in Example 1, the same evaluation as in Example 1 was performed except that plain paper having a surface resistance of 10 ¹⁰ Ω was used as the recording medium. As in Example 1, no transfer failure or transfer leak was observed.

[Example 4]
In the image forming apparatus in Example 1, the same evaluation as in Example 1 was performed except that plain paper having a surface resistance of 10 ¹⁰ Ω was used as the recording medium. As in Example 2, no transfer failure or transfer leak was observed.

[Comparative Example 1]
In the image forming apparatus in Example 1, a film label having a surface resistance of 10 ¹⁵ Ω is used as the recording medium, and a resistor having a resistance value of 10 ⁹ Ω is interposed between the ground potential and the same as in Example 1. Was evaluated. In Comparative Example 1, since a film label having a surface resistance of 10 ¹⁵ Ω was used as the recording medium, transfer failure occurred due to charging of the surface of the film label, but no transfer leak occurred.

[Comparative Example 2]
In the image forming apparatus in Example 1, the same evaluation as in Example 1 was performed except that a silver foil film having a surface resistance of 10 ⁶ Ω was used as the recording medium and the first and second static eliminating members 85 and 86 were grounded. . In Comparative Example 2, since a silver foil film having a relatively low surface resistance of 10 ⁶ Ω was used as the recording medium, transfer failure occurred due to leakage of the secondary transfer voltage.

  FIG. 11 is a table showing the results of an example performed to confirm the effect of the image forming apparatus corresponding to the second embodiment.

[Example]
In order to confirm the effect of the image forming apparatus according to the present embodiment, the present inventors performed an evaluation using a color printer manufactured by Fuji Xerox Co., Ltd .: Apeos Port IV6680.

  In this embodiment, the first and second contact members 85 and 86 are connected to the ground potential, and the first and second contact members 85 and 86 are brought into contact with the recording medium according to the type of the recording medium. It is configured to be separated.

[Example 5]
In the image forming apparatus shown in FIG. 1, a film label having a surface resistance of 10 ¹⁵ Ω is used as a recording medium, and the first and second charge removal members 85 and 86 connected to the ground potential are arranged in contact with the film label. . As a result, there was no transfer failure when the recording medium had a high resistance and no transfer leak when the recording medium had a low resistance.

[Example 6]
In the image forming apparatus in Example 1, a silver foil film having a surface resistance of 10 ⁶ Ω was used as a recording medium, and the first and second charge eliminating members 85 and 86 connected to the ground potential were not in contact with the silver foil film. The same evaluation as in Example 5 was performed. As in Example 1, no transfer failure or transfer leak was observed.

[Example 7]
In the image forming apparatus in Example 1, plain paper having a surface resistance of 10 ¹⁰ Ω was used as the recording medium, and the first and second charge removal members 85 and 86 connected to the ground potential were brought into contact with the silver foil film. The same evaluation as in Example 5 was performed. As in Example 1, no transfer failure or transfer leak was observed.

[Example 8]
In the image forming apparatus in Example 1, plain paper having a surface resistance of 10 ¹⁰ Ω is used as a recording medium, and the first and second charge eliminating members 85 and 86 connected to the ground potential are not in contact with the silver foil film. The same evaluation as in Example 5 was performed. As in Example 1, no transfer failure or transfer leak was observed.

[Example 9]
In the image forming apparatus in Example 1, the same evaluation as in Example 6 was performed except that plain paper having a surface resistance of 10 ¹⁰ Ω was used as the recording medium. As in Example 2, no transfer failure or transfer leak was observed.

[Comparative Example 3]
In the image forming apparatus of Example 5, a film label having a surface resistance of 10 ¹⁵ Ω is used as a recording medium, and a resistor having a resistance value of 10 ⁹ Ω is interposed between the ground potential and the same as in Example 1. Was evaluated. In Comparative Example 3, since a film label having a surface resistance of 10 ¹⁵ Ω was used as the recording medium, transfer failure occurred due to charging of the surface of the film label, but no transfer leak occurred.

[Comparative Example 4]
In the image forming apparatus of Example 5, the same evaluation as in Example 5 was performed, except that a silver foil film having a surface resistance of 10 ⁶ Ω was used as the recording medium and the static elimination member was grounded. In Comparative Example 4, since a silver foil film having a relatively low surface resistance of 10 ⁶ Ω was used as a recording medium, transfer failure occurred due to leakage of the secondary transfer voltage.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 5 ... Recording medium 85, 86 ... 1st and 2nd static elimination member 87 ... Switching member 101 ... Control part

Claims (5)

A toner image holding body for holding a toner image;
Transfer means for transferring the toner image held on the toner image holder to a recording medium including at least one of a recording medium having a surface resistance of 10 ⁵ to 10 ⁷ Ω and a recording medium having a surface resistance of 10 ¹⁰ to 10 ¹⁵ Ω ; ,
Obtaining means for obtaining the resistance of the recording medium;
A contact member that contacts the transfer surface of the recording medium on the upstream side in the recording medium conveyance direction of the transfer means;
According to the resistance of the recording medium acquired by the acquisition means, when the surface resistance is a recording medium of 10 ⁵ to 10 ⁷ Ω, a resistance is interposed between the contact member and the ground potential, An image forming apparatus comprising: a control unit that controls a switching unit that switches the contact member to connect to a ground potential when the recording medium has a resistance of 10 ¹⁰ to 10 ¹⁵ Ω . The contact member is electrically connected to a housing of the image forming apparatus;
The image forming apparatus according to claim 1, wherein the control unit adjusts a resistance interposed between a housing of the image forming apparatus and a ground potential. The contact member is connected to a ground potential;
The image forming apparatus according to claim 1, wherein the control unit controls the presence or absence of contact between the contact member and the recording medium.   The image forming apparatus according to claim 1, further comprising a second contact member that contacts a transfer surface of the recording medium on a downstream side of the transfer unit in the recording medium conveyance direction. .   The recording medium is made of continuous paper, and the control means includes a resistor interposed between the contact member and a ground potential including the paper feeding section and the winding section of the continuous paper, or the contact member and the recording medium. The image forming apparatus according to claim 1, wherein the presence or absence of contact is controlled.

Images