JP2007072022A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus equipped with a thermal transfer unit constituted of a thermal transfer body and a heat source, capable of attaining energy-saving by selectively driving the heat source of improved heating efficiency and thermally transferring and fixing an image on a recording material in an optimum condition, and capable of suppressing the temperature rise inside the image forming apparatus, consequently, capable of forming images of high quality on both sides of the recording material. <P>SOLUTION: In the thermal transfer unit, after the thermal transfer body 46 is heated by the heat source 48, a toner image is transferred from a first image carrier belt 21 to the thermal transfer body 46, and the thermal transfer body 46 is still more heated by the heat source 48, thereafter, the toner transferred onto the thermal transfer body 46 is simultaneously and thermally transferred and fixed on the recording material. In the thermal transfer unit, in accordance with input image information on the front and rear surface of the recording material, the heating drive of the heat source 48 is selectively turned on/off, also, the heating temperature of the heat source 48 is selectively decided, and also, the nip pressure of the transfer part is selectively decided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus including a thermal transfer unit including a thermal transfer member and a heat source.

  Conventionally, as a method for forming an image on both surfaces of a recording material, a so-called switchback method, a one-pass method, and the like are known. The switchback method reverses the recording material on which the image is formed on one side after passing through the transfer unit and the fixing unit, and then switches back to the transfer unit and the fixing unit, so that the other side also This is a method for forming an image. On the other hand, the one-pass method forms an image on both sides of the recording material without switching back the recording material by passing the recording material on which the image has been transferred on both sides by the double-side transfer unit, through the fixing unit. The one-pass method avoids any cost increase by providing a complicated mechanism for switchback, longer image formation time by switchback, and jamming by switching back the curled recording material by heating by the fixing means. It is superior to the switchback method in that it can be done.

  However, in the one-pass method, when thermal transfer and fixing are simultaneously performed from the transfer belt of the double-side transfer unit to the recording material, image deterioration is likely to occur due to the temperature increase of the transfer belt. Further, the one-pass method has a problem that energy efficiency is deteriorated by uniformly heating the transfer belt by a heat source provided in the double-side transfer unit.

In order to solve such problems, techniques for improving transfer means have been developed.
Examples of such conventional techniques include a transfer member, a driving unit that moves the transfer member along a continuous path, and a plurality of powder toners of different colors in order to form a large number of charged toner images on the transfer member. A large number of toner images are formed by electrostatic deposition means for simultaneously depositing images on the transfer member aligned with each other and substrate transport means for transporting the substrate along the substrate path to contact with the transfer member. A means for heating the multiple toner images on the transfer member prior to being transferred to at least one surface of the material, and transferring the multiple toner images to the substrate; and depositing additional toner images on the transfer member Before the image forming apparatus, an image forming apparatus (for example, see Patent Document 1) including a means for cooling a transfer member lower than a glass transition temperature of toner following transfer of a large number of toner images to a substrate. Yes.
Moreover, in the electromagnetic induction heating apparatus that heats the heating object provided with the electromagnetic induction heat generating layer, a first excitation coil that is disposed to face the heating object along a direction orthogonal to the moving direction of the heating object; An electromagnetic induction heating device comprising: a second excitation coil disposed so as to face the first excitation coil with respect to the heating object and to make a Japanese-style connection to the first excitation coil (For example, refer to Patent Document 2).
Further, an image carrier, visible image forming means for forming a toner image on the surface of the image carrier, double-sided transfer means for transferring the toner image on the image carrier to both sides of the recording body, and the recording body An image forming apparatus including a fixing unit that fixes a toner image on both sides of the image forming apparatus, wherein the fixing unit includes a belt member that moves endlessly and a plurality of tension members that are stretched while supporting the belt member from the back surface. A member, a surface heating body that heats the surface while abutting on the surface of the belt member to form a fixing nip, and a back surface side heating unit that heats the belt member from the back surface side. A toner image is fixed on both sides of the fixing nip, and a tensioning member is provided by the tensioning member disposed closest to the double-sided transfer means in the entire area in the circumferential direction of the belt member. After passing through the position, Image forming apparatus back surface side heating means is configured to heat the region to reach (for example, see Patent Document 3.) Have been disclosed.

Japanese Patent Laid-Open No. 9-179373 JP 2001-068262 A JP 2005-017869 A

  The present invention has been made in view of the above problems, and further improves the prior art, selectively drives a heat source with excellent heating efficiency, and performs thermal transfer and fixing of the recording material under optimum conditions, thereby saving energy. It is an object of the present invention to provide an image forming apparatus including a thermal transfer unit including a thermal transfer body and a heat source that can achieve temperature reduction and suppress a temperature increase in the image forming apparatus and can form a high-quality double-sided image in particular. .

In order to solve the above problems, the present invention has the following features.
The image forming apparatus of the present invention includes a plurality of image carriers, a first image forming unit that forms a first toner image on each of the plurality of image carriers according to input image information on the first surface of the recording material, A first image carrying unit comprising a first image carrying belt carrying a first toner image on an endless moving image carrying belt, and each of a plurality of image carriers according to input image information on the second surface of the recording material A second image forming unit for forming a second toner image; a second image carrying unit comprising a second image carrying belt for carrying a second toner image on an endlessly moving image carrying belt; and at least one thermal transfer An image forming apparatus comprising: a thermal transfer unit including a body and a heat source; and an opposing roller positioned to face the thermal transfer body at a transfer unit that transfers a toner image from the thermal transfer body onto a recording material. heat After the image is heated by the heat source, the toner image is transferred from the image carrier belt, and the toner transferred onto the heat transfer body is further heated by the heat source and then transferred to a recording material. And fixing is performed at the same time, and heat generation driving of the heat source is selectively turned on / off according to input image information on the front and back surfaces of the recording material.

The image forming apparatus of the present invention is characterized in that the heating temperature of the heat source is selectively determined according to input image information on the front and back surfaces of the recording material.
In the image forming apparatus of the present invention, the thermal transfer member and the opposing roller are in contact with each other at the transfer portion to form a nip, and the pressure at the nip portion is adjusted according to input image information on the front and back surfaces of the recording material. It is determined selectively.

The image forming apparatus of the present invention is characterized in that an ultrasonic generator is provided in the heat source.
In the image forming apparatus of the present invention, the heat source includes a thermal head.
In the image forming apparatus of the present invention, the heat source includes an IH device.

In the image forming apparatus of the present invention, the surface of the thermal transfer member includes a magnetic material.
In the image forming apparatus of the present invention, the toner used for image formation includes a magnetic material.

The image forming apparatus of the present invention is characterized in that the heat source is installed in the thermal transfer body or in a counter roller facing the heat transfer body.
The image forming apparatus of the present invention is characterized in that the heat source is installed outside the thermal transfer body.
The image forming apparatus of the present invention is characterized in that the heat source is installed on the transfer unit or on the upstream side of the transfer unit.

The image forming apparatus according to the present invention is characterized in that the heat source is divided into two or more parts and installed in one or a plurality of lines.
The image forming apparatus according to the present invention is characterized in that each of the divided heat sources turns on / off heat generation according to an image portion and a non-image portion of the input image.

The image forming apparatus of the present invention is characterized in that the heat source is scanned in a direction perpendicular to the recording material conveyance direction.
The image forming apparatus of the present invention is characterized in that heat generation driving is turned ON / OFF according to the image portion and the non-image portion of the input image while the heat source scans.

The image forming apparatus of the present invention is characterized in that the heating temperature of the heat source is selectively determined according to the input image density on the front and back surfaces of the recording material.
The image forming apparatus of the present invention is characterized in that the heating temperature of the heat source is selectively determined according to whether the input images on the front and back surfaces of the recording material are color or monochrome.

The image forming apparatus of the present invention is characterized in that the heating temperature of the heat source is selectively determined in accordance with whether the input images on the front and back surfaces of the recording material are pictures or characters.
The image forming apparatus of the present invention is characterized in that the heating temperature of the heat source is selectively determined according to the gloss of the input image on the front and back surfaces of the recording material and an arbitrary setting.

  Further, in the image forming apparatus of the present invention, the thermal transfer body and the facing roller are in contact with each other at the transfer portion to form a nip, and depending on the glossiness of the input images on the front and back surfaces of the recording material and any setting positions, The pressure of the nip portion is selectively determined.

The image forming apparatus according to the present invention further includes a fixing auxiliary unit downstream of the transfer unit that selectively controls the fixing temperature and the nip pressure of the fixing unit according to input image information on the front and back surfaces of the recording material. It is characterized by that.
Further, the image forming apparatus of the present invention is a portion in which image transfer on the front surface and back surface of the recording material overlaps according to input image information on the front surface and back surface of the recording material. The heating temperature of the heat source is selectively controlled at a portion that does not overlap.

  By means for solving the above-described problems, the image forming apparatus of the present invention selectively turns on / off the heat source drive of the heat source according to the input image information on the front and back surfaces of the recording material, and sets the heating temperature of the heat source. By selectively deciding, it is possible to suppress waste of energy and optimize the fixing temperature, and to suppress the temperature rise in the apparatus. Further, the fixing pressure is optimized by selectively determining the pressure of the nip portion according to input image information on the front and back surfaces of the recording material, and a high-quality double-sided image can be obtained. In addition, heating efficiency can be increased by using an ultrasonic generator, thermal head, or IH device that heats an object in direct contact with a heat source, saving energy and shortening the warm-up time as a fixing device. Leads to.

  In the image forming apparatus of the present invention, since the surface of the thermal transfer member contains a magnetic material, the heating efficiency of the thermal transfer member by the IH device is improved, leading to energy saving. Further, since the toner contains a magnetic material, the toner can be directly heated by the IH device. Rather than heating the toner by the heat of the heat source, the heating efficiency of the toner is improved, leading to energy saving.

  In addition, when the heat source is installed in the thermal transfer body or in the opposite roller, the image forming apparatus of the present invention can protect the heat source from contamination by toner, and can also save space in the apparatus. Further, when the heat source is installed outside the thermal transfer member, it is advantageous in terms of the degree of freedom in the layout in the apparatus. Furthermore, by installing the heat source at the transfer portion or upstream of the transfer portion, the toner melted by heating can be transferred reliably and efficiently to the next step.

  Further, the image forming apparatus of the present invention is characterized in that the heat source is multi-divided, so that according to the input image information on the front and back surfaces of the recording material, each divided portion of the heat source is selectively heated, By selectively determining the heating temperature of the heat source, waste of energy is suppressed, energy saving and suppression of temperature rise in the apparatus are enabled. Further, since the heat source is scanned, the number of heat sources can be reduced, the temperature rise in the apparatus can be suppressed, and the cost can be reduced.

  The image forming apparatus of the present invention controls the input image density on the front and back surfaces of the recording material and the heating temperature of the heat source that selectively generates heat depending on whether it is color or monochrome, so a high temperature is required for fixing. Even for color images where the image density is high, or color images that require high temperatures for fusing because toners of different colors are melted on top of each other, transfer and transfer at the optimum temperature based on the input images on the front and back surfaces of the recording material. Fixing can be performed and a high-quality double-sided image can be obtained. In addition, by optimizing the heating temperature, wasteful consumption of heating energy is prevented, leading to energy saving. Furthermore, since the heating temperature of the heat source that selectively generates heat is controlled according to whether the input images on the front and back surfaces of the recording material are patterns or characters, it is preferable to give gloss to give a high-quality feeling. Even for a pattern image that requires a high heating temperature for fixing, transfer and fixing can be performed at an optimum temperature based on the input images on the front and back surfaces of the recording material.

Further, the image forming apparatus of the present invention controls the heating temperature of the heat source that selectively drives the heat generation according to the gloss of the input image of the recording material and an arbitrary setting, so that the gloss image that requires a high temperature for fixing is used. In this case, transfer and fixing can be performed at an optimum temperature depending on the input images on the front and back surfaces of the recording material, and a high-quality double-sided image in accordance with the user's request can be obtained. In addition, by optimizing the heating temperature, wasteful consumption of energy is prevented, leading to energy saving.
Furthermore, since the nip pressure is selectively controlled according to the gloss of the input image of the recording material and the user's request, even for a glossy image that requires high pressure for fixing, it depends on the input images on the front and back surfaces of the recording material. Transfer and fixing can be performed under the optimum conditions, and a high-quality double-sided image can be obtained in accordance with the user's request.

  In addition, the image forming apparatus of the present invention can perform heating and pressurization when a heating temperature or pressure is insufficient in the thermal transfer / fixing unit, and can obtain a high-quality double-sided image. Furthermore, since the front and back image areas of the front and back image areas are heated at the same time, the heating temperature is selectively set lower than that of the non-overlapping image area, preventing unnecessary energy consumption. This leads to energy saving.

Embodiments according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a schematic central sectional view showing an internal configuration of an embodiment of an image forming apparatus to which the present invention is applied. Hereinafter, the configuration and operation of an image forming apparatus employing the present invention will be described in detail.

First, the configuration of the image forming apparatus will be described.
In the image forming apparatus main body 100 shown in FIG. 1, a first image carrier unit 20 having a first image carrier belt 21 that moves endlessly in the direction of the arrow across the recording material conveyance path 43A, A second image carrier unit 30 having a second image carrier belt 31 that moves endlessly in the direction of the arrow is disposed at the bottom. Four first image forming units 80Y, 80C, 80M, and 80K are provided on the upper tension surface of the first image carrier belt 21, and four first image forming units 80Y, 80C, 80M, and 80K are provided on the inclined tension surface of the second image carrier belt 31. Two image forming units 81Y, 81C, 81M and 81K are provided. The numbers Y, C, M, and K of the first and second image forming units correspond to the colors of the toner to be handled, Y means yellow, C means cyan, M means magenta, and K means black. is doing. Similarly, Y, C, M, and K are provided for the photoreceptor 1 provided in the first and second image forming units and rotating together with the first image carrying belt 21 and the second image carrying belt 31. The photoreceptors 1Y to 1K are arranged at the same interval, and at least at the time of image formation, are in contact with a part of the stretched portion between the image bearing belts 21 and 31, respectively. This contacting surface is called an image receiving surface.

A first image carrier belt 21 as an image carrier that is supported by a plurality of first image carrier belt support rollers 23, 24, 25, 26 (two), 27, 28, 29 and runs in the direction of the arrow, It is provided below the photoreceptors 1Y, 1C, 1M, and 1K in the first image forming units 80Y to 80K. The first image carrying belt 21 is endless, and is stretched and arranged so that a part of each photoconductor after the developing process comes into contact. In addition, a primary transfer roller 22 is provided on the inner peripheral portion of the first image carrying belt 21 so as to face each of the photoreceptors 1Y, 1C, 1M, and 1K. A first image carrying belt cleaning device 20 </ b> A is provided on the outer periphery of the first image carrying belt 21 at a position facing the roller 23. The first image carrying belt cleaning device 20 </ b> A wipes away unnecessary foreign matters such as toner and paper dust remaining on the surface of the first image carrying belt 21.
The members related to the image carrier belt 21 are integrally formed as the first image carrier unit 20 and can be attached to and detached from the image forming apparatus 100.

A second image carrier belt 31 as an image carrier that is supported by a plurality of second image carrier belt support rollers 33, 34, 35, 36 (two), 37, 38, 46 and runs in the direction of the arrow, The second image forming units 81Y to 81K are provided in contact with the photoreceptors 1Y, 1C, 1M, and 1K. The image bearing belt 31 is endless, and is stretched and arranged so that a part of each photoconductor after the developing process comes into contact. A primary transfer roller 32 is provided on the inner peripheral portion of the image bearing belt 31 so as to face the photoreceptors 1Y, 1C, 1M, and 1K. A second image carrier belt cleaning device 30 </ b> A is provided on the outer periphery of the second image carrier belt 31 at a position facing the roller 33. The second image carrying belt cleaning device 30A wipes off unnecessary toner remaining on the surface of the image carrying belt 31 and foreign matters such as paper dust.
The members related to the image carrier belt 31 are integrally configured as the second image carrier unit 30 and can be attached to and detached from the image forming apparatus 100.

Next, the configurations and materials of the image bearing belt, toner, and transfer roller will be described.
The image carrying belts 21 and 31 are belts having, for example, a resin film or rubber having a base thickness of 50 to 600 μm as a base, and the toner images carried by the respective photoreceptors 1 are transferred to the primary transfer rollers 22 and 32. Has a resistance value that enables electrostatic transfer to the belt surface. In one embodiment, carbon is dispersed in polyamide, and the volume resistance is adjusted to a resistance of about 10 6 to 10 12 Ωcm. The surface of the belt is improved by applying zinc stearate or the like as a lubricant to the belt surface. Further, belt detent ribs for stabilizing the running of the belt are provided on one side or both ends of the belt.

As the toner, a magnetic toner containing a magnetic material is used. For color images, Y, C, M, and K toners are appropriately used.
Also, monochrome recording using only black toner K is possible. In such a case, there are photosensitive members that are not used. Accordingly, not only the unused photoreceptors 1Y, 1C, 1M or the developing device are operated, but also a mechanism for keeping these unused photoreceptors and the image carrier belt 21 or 31 in a non-contact state is provided. In the present embodiment, an internal frame (not shown) that supports the roller 26 and the primary transfer roller 22 is provided, is rotatably supported around a certain point, and is moved in a direction away from the photoreceptor. Only the photosensitive member 1K is brought into contact with the image carrier belt 21 or 31, and an image forming process is executed, so that a monochrome image using the black toner K is created. This is advantageous in terms of improving the life of the photoreceptor.

As an embodiment, the primary transfer rollers 22 and 32 have a surface of a metal roller as a core metal covered with a conductive rubber material, and a bias is applied to the core metal portion from a power source (not shown). In the conductive rubber material, carbon is dispersed in urethane rubber, and the resistance is adjusted to a volume resistance of about 105 to 107 Ωcm.
Further, a transfer roller 46 is provided in the vicinity of the support roller 28 on the outer periphery of the first image carrying belt 21. The transfer pressure and transfer nip width at the contact portion between the support roller 28 and the transfer roller 46 can be freely controlled. The transfer roller 46 is formed by coating a heat-resistant rubber on the surface of a metal roller that is a core metal, a heat generating layer that becomes a magnetic thin film on the outside, and a toner release layer on the outermost layer. An eddy current is generated in the heat generation layer by the plurality of IH coils 48 installed therein to generate heat. By causing the transfer roller 46 to generate heat, the toner image carried by the first image carrying belt 21 is melted and transferred to the transfer roller 46. Further, the recording roller (the paper P) is passed between the transfer roller 46 and the second image carrier belt 31 and the transfer roller 46 is heated by the IH coil 48 so that the toner image carried by the transfer roller 46 is transferred to the paper. Transferred to P.
At the same time, the image by the toner carried by the second image carrying belt 31 is heated by the IH coils 47 provided in the vicinity of the support roller 34 on the outer periphery of the second image carrying belt 31, so that the image is printed on the paper P Is transcribed. Further, the transfer pressure and transfer nip width at the contact portion between the transfer roller 46 and the support roller 34 can be freely controlled according to the input image information. Separation of the paper P and the support roller 34 is performed by curvature separation based on the curvature of the support roller 34.

On the right side of the image forming apparatus 100, a paper feeding device 40 that accommodates paper P is provided. Paper feed device (tray) 40a storing a large amount of paper in a plurality of stages, for example, the upper stage, and three stages of paper feed cassettes 40b, 40c, and 40d below each are pulled out to the front (operation surface side) perpendicular to the paper surface. It is arranged to be possible. Of the sheets P stored in the sheet feed tray 40a and the sheet cassettes 40b, 40c, and 40d, the uppermost sheet is selectively fed and separated by the corresponding sheet feeding / separating means 41A to 41D. Only one sheet is reliably sent to the recording medium conveyance paths 43B and 43A by the plurality of conveyance roller pairs 42B.
A pair of registration rollers 45 is provided in the recording material conveyance path 43A in order to take a feeding timing for feeding the paper P to the paper transfer position. Further, a jogger 44 for making the position perpendicular to the sheet conveyance direction a normal position is provided in the recording medium conveyance path 43A. The jogger 44 includes guide members that move from both sides toward the edge of the paper in the paper conveyance direction, and the guides press the paper from both sides of the running paper for a moment to align the paper at a predetermined position. . The sheet P is conveyed from the registration roller pair 45 toward a transfer area constituted by the transfer roller 46 and the support roller 34.
Note that the recording medium conveyance path 43C having the conveyance roller pair 42C can be supplied with paper from another sheet feeding device 300 that can be additionally installed upstream in the conveyance direction. The upper sheet feed surface of the sheet feed tray 40a is arranged so that the uppermost sheet in the sheet feed tray 40a is fed and then conveyed substantially horizontally without being bent. Therefore, even thick paper and highly rigid paperboard can be reliably fed. In addition, it is convenient to adopt an air paper feed made up of a vacuum mechanism so that the paper feed tray 40a can reliably feed papers having various characteristics.

In order to convey the sheet that has passed through the second transfer station on the extension of the recording medium conveyance path 43A to the fixing nip in the fixing auxiliary device 60 provided downstream in the conveyance direction of the recording medium in a plane state. The recording medium transport means 50 is provided. The recording medium transporting unit 50 has rollers 52, 53, 54, 55, 56 that support a transport belt 51 that moves endlessly in the direction of the arrow. A cleaning device 50A is provided.
As the conveyor belt 51, a metal belt, a polyimide belt, a polyamide belt, or the like can be used. The surface is provided with releasability from the toner and has a chargeable resistance value. The traveling speed of the conveying belt 51 is matched with the traveling speed of the recording medium in the fixing device.

Next, operations during single-sided recording and double-sided recording of the image forming apparatus will be described.
First, in the configuration of the image forming apparatus 100 described above, an operation during single-sided recording in which a full-color image is formed on one side of the paper P will be described.
There are basically two types of single-sided recording methods that can be selected. One of the two types is a method in which an image carried on the first image carrying belt 21 is directly transferred to one side of the paper P, and the other method is an image carried on the second image carrying belt 31 on the paper. This is a method of transferring directly to one side of P. In the present embodiment, due to the configuration of the image forming apparatus 100, when the image carried on the first image carrying belt 21 is directly transferred to one side of the paper P, the image is placed on the upper surface of the paper P and the second image carrying belt 31. When the image carried on the sheet P is directly transferred to one side of the paper P, the image is formed on the lower surface of the paper P. In the case where the data to be recorded is a plurality of pages, it is convenient to control the image forming order so that the pages are aligned on the paper discharge stack unit 75.

In the following, a method will be described in which an image is carried on the first image carrying belt 21 and then transferred onto a sheet so that the image order is recorded in order from the image data of the last page and the page order is aligned.
When the image forming apparatus 100 is operated, the photoreceptors 1Y, 1C, 1M, and 1K in the first image carrying belt 21 and the first image forming units 80Y to 80K rotate. At the same time, the second image carrier belt 31 rotates. However, the photoreceptors 1Y, 1C, 1M, and 1K in the second image forming units 81Y to 81K are separated from the second image carrier belt 31 and are not rotated. First, image formation by the image forming unit 80Y is started. By the operation of an exposure device comprising an LED (light emitting diode) array and an imaging element, light corresponding to image data for yellow emitted from the LED is irradiated onto the surface of the photoreceptor 1Y uniformly charged by the charging device. An electrostatic latent image is formed.
This electrostatic latent image is developed with yellow toner by a developing roller, becomes a visible image, electrostatically on the first image carrying belt 21 that moves in synchronization with the photoreceptor 1Y by the transfer action of the primary transfer roller 22. Primary transfer is performed. Such latent image formation, development, and primary transfer operations are sequentially performed in the same manner on the photosensitive members 1C, 1M, and 1K.
As a result, yellow, cyan, magenta, and black toner images are carried on the first image carrying belt 21 as sequentially overlapping full-color toner images, and are moved in the direction of the arrow together with the first image carrying belt 21. .

  At the same time, the paper P used for recording is fed out from the paper feed tray 40a or the paper feed cassettes 40b to 40d in the paper feed device 40 by one of the paper feed / separation means 41A to 41D for feeding the paper P. The pair 42B and 42C are conveyed to the recording material conveyance path 43C. Before the leading edge of the sheet is added to the registration roller pair 45, the jogger 44 operates to push both sides of the sheet from both lateral directions with respect to the sheet conveying direction, and the positional alignment in the lateral direction of the sheet starts. It is. The registration roller pair 45 is stationary, and the leading edge of the sheet is stationary while entering the nip of the registration roller pair 45, but the timing is set so that the position with the image on the first image carrier belt 21 is normal. Then, the registration roller pair 45 is rotated to convey the sheet to the transfer area.

  This full-color toner image on the first image carrying belt 21 is transferred via the transfer roller 46 to the upper surface of the paper P conveyed in synchronization with the first image carrying belt 21 by the transfer action by the IH coil 48. Is done. Thereafter, the surface of the first image carrying belt 21 is cleaned by the belt cleaning device 20A. Next, the paper P and the support roller 34 are separated by curvature separation based on the curvature of the support roller 34.

The paper P onto which the toner image that has been superposed and carried on the image carrying belt 21 is transferred is transferred toward the fixing auxiliary device 60 by the carrying belt 51 of the carrying device 50. The paper P is separated from the transport belt 51 and sent to the fixing auxiliary device 60.
When the thermal transfer / fixing by the IH coil 48 is insufficient, the toner of each color superimposed on the paper P is subjected to the fixing action by the heat of the fixing auxiliary device 60, and is melted and mixed to completely form a color image. Become. Since toner is contained only on one side (upper surface) of the paper, less heat energy is required for fixing compared to double-sided recording with toner on both sides. A control means (not shown) optimally controls the power used by the fixing auxiliary device 60 according to the image. Until the fixed toner is completely fixed on the paper, it is rubbed against the guide member or the like in the conveyance path, and the image is lost or distorted. In order to prevent this problem, the cooling roller pair 70, which is a cooling means, operates to cool the toner and the paper. Thereafter, the paper is discharged by the paper discharge roller 71 onto the paper discharge stack 75 with the image surface facing upward. In the paper discharge stack section 75, the image forming order is programmed so that the recorded matter of the young pages is stacked so as to be sequentially stacked on top, so the page order is aligned. Since the paper discharge stack unit 75 is lowered as the number of discharged paper sheets increases, the paper sheets can be stacked in an orderly and reliable manner, and the page order is not disturbed. Instead of stacking the recorded paper directly on the paper discharge stack section 75, it is possible to carry out a punching process or to transport it to a post-processing device such as a sorter, a collator, a binding device or a folding device.

  In another method for forming an image on one side of the paper P, image formation is not performed in the first image forming units 80Y to 80K, and image formation is performed in order from image data of young pages for page alignment. However, since it is basically the same as the single-sided recording process, details are omitted.

Next, the operation at the time of double-sided recording in which a full color image is formed on both sides of the paper P in the configuration of the image forming apparatus 100 will be described.
When image information is input to the image forming apparatus 100 and a start signal is input, the first image carrier unit 20 serves as a transfer unit that performs transfer of the first image and the second image that are formed based on the input image information. And image formation is started after selection from the second image carrier unit 30. This time, the first image is formed by the first image carrier unit 20 and the second image is formed by the second image carrier unit 30.
The first image for each color sequentially formed by the first image forming units 80Y, 80C, 80M, and 80K described in the single-side recording operation is sequentially primary-transferred to the first image carrying belt 21 as a first image. In parallel with the carrying step, the second image for each color sequentially formed by the second image forming units 81Y, 81C, 81M, and 81K is sequentially primary transferred to the second image carrying belt 31 and carried as a second image. The process of making is performed. Since the sheet P is stopped and retransmitted by the registration roller pair 45, the sheet P is fed in consideration of the time and aligned by the jogger 44. The registration roller pair 45 conveys the paper P to a transfer station constituted by the transfer roller 46 and the second image carrying belt 31 at a timing. The transfer roller 46 is heated by the IH coil 48, and the image is transferred from the first image carrying belt 21 to the one side (upper surface in the drawing) of the paper P via the transfer roller 46. Further, before execution of transfer, transfer conditions (transfer temperature, transfer pressure) are controlled based on input image information.
At the same time, the full-color second image previously carried on the second image carrying belt 31 is melted on the paper P by the IH coil 47 and transferred to the lower surface of the paper P at once.
Further, before execution of transfer, transfer current is controlled based on input image information. Next, the paper P and the support roller 34 are separated by curvature separation based on the curvature of the support roller 34.

  At this time, the first image is formed by the first image carrier unit 20 and the second image is formed by the second image carrier unit 30. Depending on the conditions of the image information, the second image is formed by the first image carrier unit 20. There is also a step of forming an image of the first image with the second image carrier unit 30. Details are omitted because they are basically the same as the above steps.

The sheet P having the full-color toner image transferred on both sides in this way is transferred to the fixing auxiliary device 60 by the transport belt 51. The paper P is separated from the belt 51 and transferred to the fixing auxiliary device 60. When the thermal transfer / fixing by the IH coil 47 or 48 is insufficient, the toner image on both sides of the paper P is melted and mixed by receiving the fixing process by the fixing auxiliary device 60. The sheet P continues to pass through the cooling roller pair, and is discharged onto the discharge stack unit 75 by the discharge roller 71.
When double-sided recording is performed on a plurality of pages of paper P, the paper P in which the order of contribution is reversed by a switchback mechanism (not shown) provided after the transfer in order to align the page order of the paper P in the paper stack unit 75. The direction of discharging is corrected. Thus, the page order of the recorded matter when it is taken out from the paper stack portion 75 is aligned. Such control of image forming sequence and control such as increasing the power input to the fixing device compared to the one-side recording are executed by a control means (not shown).
Here, an example in which full-color recording is executed regarding single-sided recording and double-sided recording operations has been described, but monochrome recording using only black toner is also possible.

Embodiments according to the present invention will be described below in detail with reference to the drawings.
FIG. 2 illustrates a first image forming unit that forms a first surface of an image, a first image carrying unit, a second image forming unit that forms a second surface of an image, and a second image carrying unit, at least one or more, It is the elements on larger scale of the example which produced the image forming apparatus provided with the thermal transfer unit which consists of a thermal transfer body and a heat source (an ultrasonic generator, an IH apparatus, a thermal head). This device is characterized by the simultaneous transfer and fixing to the paper, and it has first and second thermal transfer / fixing sections that transfer the unfixed image on the paper formed with toner once to both sides of the paper. And a mechanism for controlling ON / OFF of the heat source drive of the heat source, the heating temperature, and the nip pressure of the thermal transfer / fixing unit according to input image information (image pattern, image density, color / monochrome, etc.). Further, the thermal transfer member and the toner used in this apparatus contain a magnetic material.

  The ultrasonic generator, IH device, and thermal head of the heat source that can be installed in the apparatus of FIG. 2 do not directly heat the object with infrared rays through an air layer like a halogen heater, but directly contact the object. Therefore, since the heating efficiency is better than the heating method using radiation, the energy saving effect of this embodiment is obvious. It is also clear that the temperature rise in the apparatus is suppressed by the loss of energy consumption.

  In this embodiment, image formation was performed by an image forming apparatus having a configuration as shown in FIG. 2G, and 1000 fixed double-sided images were output. After output, when the ultrasonic generator of the first transfer unit and the IH device of the second transfer unit were taken out, the ultrasonic generator of the first transfer unit was markedly contaminated with toner and paper dust. On the other hand, almost no contamination was observed in the IH device of the second transfer portion. From this, it became clear that the heat source can be protected from dirt such as toner by installing the heat source in the thermal transfer body.

FIG. 3A is a graph showing the result of thermal transfer / fixing of a toner image by a single row of IH devices. It shows how much energy can actually be saved. Similarly, FIG. 3B shows a case where thermal transfer / fixing is performed by a plurality of rows of IH devices.
In this embodiment, toner images are formed on the thermal transfer member in order from the top as shown in FIG. 3A by the image forming apparatus having the configuration shown in FIG. 2A, and this toner image is carried. The thermal transfer body and paper are thermally transferred and fixed by the image forming apparatus shown in FIG. 2A. At that time, the IH apparatus is used in the part where there is no image as shown in the pulse integral waveform shown in FIG. When passing, the energization to the IH device is OFF (0), and the power loss is zero. On the other hand, when the toner image in FIG. 3A comes to the IH device, a pulse is applied to the IH device and the energization is turned on (1). Further, the toner image is turned off when the toner image has passed. Therefore, compared with the case where the same energization is performed for all the sheets of paper, power can be saved by completely turning off the energization between images as in this embodiment. Further, the image forming apparatus of FIG. 2A is expected to save power on both the front surface and the back surface, so that significant power saving is expected. Actually, since an image such as a sentence always includes a line space (a portion without an image) between character lines, it is expected that clear energy saving can be achieved by turning off the energization between the image lines. Is obvious.

FIG. 4 is a graph showing the result of turning on / off the heat generation drive of the heat source according to the image pattern. It shows how much energy can be saved by actually transferring and fixing a toner image with a scanning thermal head.
In this embodiment, toner images are formed on the thermal transfer member in order from the top as shown in FIG. 4 by the image forming apparatus having the configuration shown in FIG. 2B, and the thermal transfer member carrying the toner image and paper 2B is thermally transferred and fixed by the image forming apparatus shown in FIG. 2B. At that time, when the thermal head scans a portion where there is no image as shown in the pulse integral waveform shown in FIG. The energization to is in an OFF (0) state, and the power loss is zero. On the other hand, when the thermal head scans the portion of the toner image in FIG. 4, a pulse is applied to the thermal head and energization is turned ON (1). When the toner image has been scanned, it is turned off. Therefore, compared with the case where the same energization is performed for all the sheets of paper, power can be saved by completely turning off the energization between images as in this embodiment. Further, the image forming apparatus of FIG. 2B is expected to save power on both the front surface and the back surface, and is expected to save significant power. Actually, since an image such as a sentence always includes a line space (a portion without an image) between character lines, it is expected that clear energy saving can be achieved by turning off the energization between the image lines. Is obvious.

FIG. 5 is a graph showing a result of controlling the heating temperature of the heat source by the toner adhesion amount. It shows how much energy can be saved by actually transferring and fixing a toner image with an ultrasonic device. In this embodiment, a color toner image is formed on the thermal transfer member in order from the top as shown in FIG. 5 by the image forming apparatus having the configuration shown in FIG. 2F, and the thermal transfer member carrying the toner image is formed. 2 (f) is used for thermal transfer / fixing, and at that time, the portion where the toner overlap amount is small (1C portion) as shown in FIG. 5 is an ultrasonic wave. When passing through the generator, the heating temperature of the ultrasonic generator is set low, and the power loss is reduced compared to the case without temperature control. On the other hand, when a portion (4C portion) with a large amount of toner overlap in FIG. 5 comes to the ultrasonic generator, the set temperature of the ultrasonic generator is set high. Therefore, compared to heating all the sheets of paper at the same temperature, power can be saved by controlling the heating temperature in the toner adhesion amount as in this embodiment.
Actually, in addition to the temperature control for the toner adhesion amount such as color and monochrome as in the present embodiment, the heating temperature control is also performed for the toner adhesion amount such as the image density and the pattern / character. It is obvious. Furthermore, since the fixing temperature corresponding to the toner adhesion amount is set, a high-quality fixed image can be obtained.

  FIG. 6 is a graph showing the result of thermal transfer and fixing of image images with different glossiness using an ultrasonic device. It shows how much energy can actually be saved. In this embodiment, the image forming apparatus configured as shown in FIG. 2C forms images with different glosses in order from the top on the thermal transfer member as shown in FIG. 6, and the thermal transfer carrying this toner image. The body and paper are thermally transferred and fixed by the image forming apparatus shown in FIG. 2C. At that time, as shown in the pulse integral waveform shown in FIG. When passing, the heating temperature of the ultrasonic generator is set low, and the loss of power is reduced compared to the case without temperature control. On the other hand, when a portion with high image glossiness in FIG. 6 comes to the ultrasonic generator, the set temperature of the ultrasonic generator is set high. Therefore, compared to heating all the sheets of paper at the same temperature, power can be saved by controlling the heating temperature in the toner adhesion amount as in this embodiment. Further, the image forming apparatus of FIG. 2C is expected to save power on both the front surface and the back surface and is expected to save a great amount of power. Since the fixing temperature corresponding to the image glossiness is set, a high-quality fixed image can be obtained. Further, by selectively setting the pressing force in accordance with the glossiness, a higher quality fixed image can be obtained. Further, by providing a fixing auxiliary means 60 as shown in FIG. 1 downstream of FIG. 2C, when a shortage of fixing temperature or fixing pressure occurs in the transfer / fixing section of FIG. Heating and pressurization can be performed, and high-quality fixed images can be obtained stably.

  FIG. 7 is a graph showing the result of controlling the heating temperature of the heat source by overlapping the image portions on the front and back surfaces of the recording material. In the portion Y where the front and back image portions overlap, the front and back surfaces of the recording material are heated at the same time. Therefore, the heating temperature is selectively set lower than the portion X where the image portions do not overlap, thereby saving power. Energy saving effect is obtained.

  FIG. 8 is a graph showing the result of controlling the heating temperature of the heat source by overlapping images. It shows how much energy can be saved by actually transferring and fixing a toner image with a plurality of rows of IH devices. In this embodiment, as shown in FIG. 8, a toner image on the front surface and the back surface is formed on the thermal transfer member as shown in FIG. 8 by the image forming apparatus configured as shown in FIG. 2D, and the thermal transfer member carrying the toner image is shown in FIG. The image forming apparatus 2 (d) performs thermal transfer / fixing. At that time, as shown in the pulse integral waveform shown in FIG. 8, when the overlapping portion of the toner images on the front and back surfaces passes through the IH apparatus. Is in a state where the heating temperature of the IH device is lowered, and power consumption is suppressed. Therefore, as compared with the case where the same energization is performed for all the sheets of paper, the heating temperature can be reduced at the portion where the toner images overlap as in this embodiment, so that power can be saved. Furthermore, the image forming apparatus of FIG. 2D is expected to save power on both the front surface and the back surface, and a significant energy saving effect is obvious.

1 is a schematic central sectional view showing an internal configuration of an embodiment of an image forming apparatus to which the present invention is applied. FIG. 3 is a partially enlarged view of an example in which an image forming apparatus including an image forming unit and a unit and at least one thermal transfer unit is manufactured. FIG. 3 is a partially enlarged view of an example in which an image forming apparatus including an image forming unit and a unit and at least one thermal transfer unit is manufactured. 6 is a graph showing the result of thermal transfer and fixing of a toner image with an IH device. It is the graph which showed the result which turned on / off the heat generation drive of the heat source with the image pattern. 6 is a graph showing the result of controlling the heating temperature of the heat source according to the toner adhesion amount. 6 is a graph showing the result of thermal transfer and fixing of images with different glossiness using an ultrasonic device. 6 is a graph showing the result of controlling the heating temperature of the heat source by overlapping the image portions on the front and back surfaces of the recording material. It is the graph which showed the result of having controlled the heating temperature of the heat source by image superposition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 20 First image carrier unit 20A First image carrier belt cleaning device 21 First image carrier belt 22 Primary transfer rollers 23 to 29 Belt support roller 30 Second image carrier unit 30A Second image carrier belt Cleaning device 31 Second image carrier belt 32 Primary transfer rollers 33 to 38 for second image carrier unit Second image carrier belt support roller 40 Paper feeder 40a Upper paper feeder (tray)
40b to 40d Paper feed cassettes 41A to 41D Paper feed / separation means 42A to 42C Transport roller pair 43A to 43C Recording medium transport path 44 Jogger 45 Registration roller pair 46 Transfer roller (thermal transfer body)
47, 48 IH coil (heat source)
50 Recording medium transporting means 50A Conveyor belt cleaning device 51 Conveyor belts 52 to 56 Conveyor belt support roller 60 Fixing auxiliary device 70 Cooling roller pair 71 Discharge roller pair 75 Discharge stack unit 80 First image forming unit 81 Second Image forming unit 85 Toner cartridge storage part 86 Toner cartridge 87 Waste toner recovery part 90 Operation / display part (unit)
95 Electrical Equipment / Control Device 100 Image Forming Device 200 Image Reading Device 300 Paper Feed Device F that can be additionally installed F Fan

Claims (22)

A plurality of image carriers;
A first image forming unit for forming a first toner image in accordance with input image information on the first surface of the recording material on each of a plurality of image carriers, and a first toner image on an endlessly moving image carrier belt A first image carrying unit comprising a first image carrying belt;
A second image forming unit for forming a second toner image in accordance with input image information on the second surface of the recording material on each of the plurality of image carriers, and a second toner image on an endlessly moving image carrier belt A second image carrying unit comprising a second image carrying belt;
At least one thermal transfer unit comprising a thermal transfer body and a heat source;
An image forming apparatus comprising: a transfer unit that transfers a toner image from a thermal transfer member onto a recording material; and an opposing roller that faces the thermal transfer member,
The thermal transfer unit is configured to transfer a toner image from the image bearing belt after the thermal transfer member is heated by the heat source, and to transfer the toner onto the thermal transfer member after the thermal transfer member is further heated by the heat source. , Thermal transfer to the recording material and fixing are done simultaneously,
An image forming apparatus, wherein the heat source drive of the heat source is selectively turned on / off according to input image information on the front and back surfaces of the recording material.   The image forming apparatus according to claim 1, wherein the image forming apparatus selectively determines a heating temperature of the heat source according to input image information on a front surface and a back surface of a recording material.   The image forming apparatus forms a nip by contacting the thermal transfer body and the opposing roller at the transfer portion, and selectively determines the pressure of the nip portion according to input image information on the front and back surfaces of the recording material. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the heat source includes an ultrasonic generator.   The image forming apparatus according to claim 1, wherein the heat source includes a thermal head in the heat source.   The image forming apparatus according to claim 1, wherein the heat source includes an IH device.   7. The image forming apparatus according to claim 1, wherein the surface of the thermal transfer member includes a magnetic material.   The image forming apparatus according to claim 1, wherein the toner used for image formation includes a magnetic material.   9. The image forming apparatus according to claim 1, wherein the heat source is installed in the thermal transfer body or in a counter roller facing the heat transfer body.   The image forming apparatus according to claim 1, wherein the heat source is installed outside the thermal transfer body.   The image forming apparatus according to claim 1, wherein the heat source is installed on the transfer unit or on the upstream side of the transfer unit.   12. The image forming apparatus according to claim 1, wherein the heat source is divided into two or more parts and installed in one or a plurality of lines.   13. The image forming apparatus according to claim 12, wherein each of the divided heat sources turns on / off heat generation according to an image portion and a non-image portion of an input image.   The image forming apparatus according to claim 1, wherein the heat source is scanned in a direction perpendicular to a recording material conveyance direction.   The image forming apparatus according to claim 1, wherein the image forming apparatus turns on / off heat generation driving according to an image portion and a non-image portion of an input image while the heat source scans. apparatus.   16. The image forming apparatus according to claim 1, wherein the image forming apparatus selectively determines a heating temperature of the heat source according to input image densities on the front and back surfaces of the recording material. .   17. The image forming apparatus according to claim 1, wherein the heating temperature of the heat source is selectively determined according to whether the input images on the front and back surfaces of the recording material are color or monochrome. Image forming apparatus.   18. The image forming apparatus according to claim 1, wherein the heating temperature of the heat source is selectively determined according to whether the input images on the front and back surfaces of the recording material are pictures or characters. Image forming apparatus.   The image forming apparatus according to any one of claims 1 to 18, wherein the image forming apparatus selectively determines a heating temperature of the heat source according to a gloss of an input image on a front surface and a back surface of a recording material and an arbitrary setting position. The image forming apparatus described in 1.   In the image forming apparatus, the thermal transfer member and the opposing roller are in contact with each other at the transfer unit to form a nip. Depending on the gloss of the input image on the front surface and the back surface of the recording material or an arbitrary setting, The image forming apparatus according to claim 1, wherein the pressure is selectively determined.   The image forming apparatus includes a fixing auxiliary unit downstream of the transfer unit that selectively controls a fixing temperature and a nip pressure of the fixing unit according to input image information on the front and back surfaces of the recording material. The image forming apparatus according to claim 1.   The image forming apparatus performs thermal transfer and fixing on the front and back surfaces of the recording material at the same time, and does not overlap a portion where the image portions on the front and back surfaces of the recording material overlap according to input image information on the front and back surfaces of the recording material. The image forming apparatus according to claim 1, wherein the heating temperature of the heat source is selectively controlled in a part.

Images