JP2013186372A - Cascade printing device, and cascade printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a level difference in glossiness of a first face of a recording material or a difference in glossiness between the first face of the recording material and a second face of the recording material, in a cascade image forming apparatus in which a single image forming apparatus is connected thereto, a first image forming apparatus prints the first face of the recording material, and a second image forming apparatus prints the second face of the recording material.SOLUTION: The fixing speed of a second image forming apparatus forming an image second time or after, or the rotation speed of a pressure member, or the rotation speed of an external heating member are respectively set faster than the fixing speed of a first image forming apparatus forming an image initially (first), or the rotation speed of the pressure member, or the rotation speed of the external heating member according to the type of a print medium.

Description

  The present invention relates to a fixing device that fixes a toner image on a recording material and a multiple image forming device that forms an image by connecting a plurality of image forming apparatuses including the fixing device.

  Among the above-mentioned printing or recording methods, for example, in electrophotography, the photoconductive photoreceptor is charged and exposed to form an electrostatic charge latent image on the photoreceptor, and this electrostatic charge latent image is then used as a binder for the resin. Development is performed with fine particle toner containing a colorant and the like, the obtained toner image is transferred onto a recording paper, and the obtained unfixed toner image is heated and melt-fixed to obtain a recorded image.

  Among the above-mentioned printing or recording methods, for example, in electrophotography, the photoconductive photoreceptor is charged and exposed to form an electrostatic charge latent image on the photoreceptor, and this electrostatic charge latent image is then used as a binder for the resin. Development is performed with fine particle toner containing a colorant and the like, and the obtained toner image is transferred onto a recording paper and fixed to obtain a recorded image.

  In such an electrostatic image recording process, it is important to always provide a stable and clean image quality, and always maintain the development conditions of the developing device for visualizing the electrostatic latent image in a satisfactory state. Is particularly important.

  Conventionally, in an electrophotographic apparatus in which two apparatuses are connected by a tandem method, the printing paper fed to the second apparatus passes through the first fixing apparatus. It is in a state of remaining heat. Therefore, although it is advantageous for fixing of the second apparatus, the image printed on the first apparatus may reach an overheated state by being fixed twice, and the sheet kept at a relatively high temperature. When the sheets are discharged and stacked as they are, the toners may stick to each other, and a so-called toner stick phenomenon that the toner is peeled off when the paper is cut may easily occur. Both the fixing quality of the printed image and the toner stick after paper discharge depend on the heating roll temperature of the fixing device and the paper temperature, so it is necessary to manage the temperature rise in the machine to provide high-quality electrophotographic images. It was done.

  In addition, in order to provide a stable electrophotographic apparatus, it is also known to control the temperature inside the apparatus (see, for example, Patent Documents 1, 2, 3, 4, and 5).

  Further, the glossiness of an image obtained when the obtained toner image is transferred onto a recording paper and fixed by heating, melting, and fixing greatly depends on the time for which the unfixed image passes through the fixing device. Therefore, as described above, in the electrophotographic apparatus in which the two apparatuses are connected by the tandem method, the printing paper fed to the second apparatus passes through the first fixing apparatus. Since the paper temperature has been raised in advance and the preheated state has been reached, there is a problem that the glossiness of the images fixed on the first and second units differs.

  According to Patent Document 6 as a conventional example, a countermeasure is taken by changing the heating temperature control set value temperature of the fixing device of the second device. However, such countermeasures by heating temperature control require time (downtime) for temperature control, which leads to a decrease in productivity.

Japanese Patent Laid-Open No. 58-1000072 JP-A-5-85018 JP 11-95642 A JP 2004-301948 A JP 2004-325637 A JP 2006-330456 A

  As described above, in the conventional electrophotographic apparatus, the temperature of the paper is excessively increased by supplying heat to the toner on the paper in order to improve the image quality after fixing, and the paper temperature after the paper discharge is increased. When it is not low, a toner stick occurs.

  Further, in a fixing device having a heat source inside the pressure roller in order to improve the fixing property, when the recording material second surface is fixed by the fixing device of the second image forming apparatus, the pressure roller is applied to the recording material first surface. There arises a problem of uneven gloss (gloss) of the period.

  This is because the pressure roller is maintained at a high temperature during standby, and the pressure roller is further heated by the fixing roller in a pre-rotation before the pressure roller rotates while being pressed against the fixing roller, and the temperature rises. Then, when the recording material passes through the fixing nip portion, the heat of the pressure roller is rapidly taken away by the recording material, and the pressure roller temperature is lowered. Therefore, the first rotation of the pressure roller on the first surface of the recording material is caused by the high-temperature pressure roller, the toner is remelted and the glossiness is greatly increased to increase the glossiness. Since the toner is not easily remelted by the pressure roller, the increase in glossiness is small, so the change in glossiness is small. Therefore, an image in which the second surface of the recording material is fixed by the second image forming apparatus has a gloss level difference on the first surface of the recording material, and the image quality is degraded.

  In a fixing device having no heat source inside the pressure roller, the pressure roller temperature is low, and the toner on the first surface of the recording material is difficult to remelt. Unevenness is unlikely to occur.

  However, the output image in which the second surface of the recording material is fixed by the second image forming apparatus has a problem of gloss difference between the first surface and the second surface of the recording material.

  This is because when the first image forming apparatus fixes the first surface of the recording material, the recording material temperature is fixed at a low temperature (room temperature), and therefore the glossiness is relatively low. On the other hand, when the recording material second surface is fixed by the second image forming apparatus, the recording material is once heated by the fixing device of the first image forming apparatus, and the recording material second surface is fixed while the recording material temperature is high. Therefore, the glossiness becomes relatively high. Therefore, in the output image in which the recording material second surface is fixed by the second image forming apparatus, a gloss difference is generated in which the glossiness of the recording material first surface is low and the glossiness of the recording material second surface is high, Image quality is degraded.

  The above two problems are likely to occur with thick paper in which the pressure roller temperature tends to decrease, or smooth paper or gloss coated paper with high glossiness.

  Therefore, according to the present invention, in the multi-layer image forming apparatus, no toner stick is generated on the discharged paper, and gloss unevenness (gloss level difference) due to the pressure roller temperature on the first surface of the recording material at the time of duplex printing is obtained. To improve the gloss uniformity of the first surface of the recording material, and to prevent the gloss difference between the first surface and the second surface of the recording material, so that the first surface and the second surface of the recording material are glossy. An object of the present invention is to provide a multiple image forming apparatus that improves uniformity.

The above problem is that an electrostatic latent image is formed on a photoconductor, the electrostatic latent image is visualized by developing toner of a developing device using a two-component developing system, and the visualized toner image is transferred to a transfer device. The toner image transferred onto the recording medium is fixed by a fixing device having a heating device and a temperature sensor for detecting the heating temperature to obtain a recorded image, which remains on the photoreceptor. Two electrophotographic apparatuses having a series of electrostatic latent image recording processes for removing the toner by a cleaning device and preparing for the formation of the next electrostatic latent image are continuously connected, and the fixing device and the second unit of the first device are connected. A control mechanism that compares and controls the detected heating temperature of the fixing device of the apparatus and a set value temperature is provided, and after developing, fixing, and ejecting paper that has been developed, fixed, and discharged by the first device, it is developed.・ In a continuous image forming device that prints continuously by fixing and ejecting paper , Located upstream of the transport path of the print medium than the first unit of the printing apparatus, and the basis weight and the basis weight, paper type detection means for detecting the paper type of the print medium,
As a result of detection by the basis weight / paper type detection means, the fixing speed in the first apparatus and the second apparatus by the control means for amplifying the fixing speed of the fixing apparatus in the second apparatus according to the type of print medium. This can be solved by changing the fixing speed at.

  According to the present invention, a multiple image that reduces gloss unevenness (gloss level difference) due to the pressure roller temperature of the first surface of the recording material during double-sided printing and improves the gloss uniformity of the first surface of the recording material. A forming apparatus can be provided. Further, by not changing the fixing temperature, it is possible to provide an electrophotographic apparatus that ensures stable fixing strength and does not generate a toner stick after paper discharge. At this time, even if the fixing speed of the fixing device of the second image forming apparatus is set high, the recording material is heated by the fixing device of the first image forming apparatus and conveyed to the fixing device of the second image forming apparatus in a high temperature state. Therefore, the fixability of the recording material second surface is equal to or better than the fixability of the recording material first surface.

1 is a schematic configuration diagram of a multiple image forming apparatus according to Embodiment 1 of the present invention. It is a schematic block diagram of the other image forming part which concerns on Example 1 of this invention. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention. 1 is a schematic configuration diagram of a fixing roller or a pressure roller according to Embodiment 1 of the present invention. It is a heat transfer SIM calculation condition figure of paper surface temperature concerning Example 1 of the present invention. It is a heat transfer SIM result of paper surface temperature based on Example 1 of this invention. It is a schematic block diagram of the paper type and basic weight detection means based on Example 2 of this invention. FIG. 9 is a schematic configuration diagram between a fixing device and a transfer device according to a third embodiment of the present invention.

[Example 1]
Embodiments of the present invention will be described below with reference to the drawings.

(1) Double continuous printing system FIG. 1 is an explanatory diagram of a schematic configuration of a multiple continuous printing system of the present embodiment. In this redundant printing system, a plurality of printing apparatuses, in this example, two printing apparatuses, a first printing apparatus 1 and a second printing apparatus 2 are connected in cascade, and the two printing apparatuses are connected. This is a system for performing continuous printing with a printing apparatus. First, the paper feeding device 4 stores the recording paper P and continuously supplies it to the multiple continuous printing system.

  Next, the first printing apparatus 1 and the second printing apparatus 2 will be described. For the recording paper P supplied by the paper feeding device 4, first, surface printing is performed by the first printing device 1, and then the transport path of the recording paper P with respect to the recording paper P after printing. Above, the 2nd printing apparatus 2 located downstream from the 1st printing apparatus 1 performs back surface printing. The first printing device 1 and the second printing device 2 continuously print images on the same recording paper P supplied by the paper feeding device 4.

  In this case, the double continuous printing system is used for double-sided printing, and printing is performed by the first printing device 1 on one side (front surface) of the recording paper P supplied from the paper feeding device 4. The second printing apparatus 2 executes the multiple continuous printing for printing the other side (back side) of the recording paper P, and the first printing apparatus 1 and the second printing apparatus 2 share the front and back printing. I have to.

  In this way, the first printing device 1 and the second printing device 2 continuously print a large number of images on the recording paper P.

  The front / back reversing device 5 is provided on the conveyance path of the recording paper P between the first printing device 1 and the second printing device 2, and the surface of the recording paper P whose surface is printed by the first printing device 1. The second printing apparatus 2 is supplied with the front and back reversed, so that the second printing apparatus 2 can also print on the back surface of the recording paper P.

  The post-processing device 6 performs necessary post-processing on the recording paper P that has been printed by the first printing device 1 and the second printing device 2. In this example, the recording paper P is stacked so that the front and back directions are aligned. The buffer device 7 buffers the recording paper P supplied to the post-processing device 6 after the printing on the back surface printing device 3 is completed.

  Next, a detailed configuration of each apparatus constituting the double continuous printing system will be described.

  FIG. 2 is an explanatory diagram showing a schematic configuration of the first printing apparatus 1 and the second printing apparatus 2. Since the first printing apparatus 1 and the second printing apparatus 2 have the same device configuration, the first printing apparatus 1 will be described as a representative here.

  The first printing apparatus 1 is a printing apparatus that forms a color image by electrophotography. In this example, the printing method is a multiple transfer tandem method. That is, in the first printing apparatus 1, an image of black (hereinafter simply referred to as “K”) is formed from the upstream side in the transport direction (the direction of arrow 11) along the transport path of the recording paper P. Image station 12K, image station 12C forming an image of cyan (hereinafter simply referred to as “C”), image station 12M forming an image of magenta (hereinafter simply referred to as “M”), yellow (hereinafter referred to as “C”) The image stations 12Y that form an image of a color “Y” are sequentially arranged. By sequentially moving the image stations 12K, 12C, 12M, and 12Y through the conveyance path, toner images of K, C, M, and Y are sequentially superimposed on the continuous paper P, and thus are continuously formed. A color image is formed on the paper P.

  Each image station 12K, 12C, 12M, 12Y is provided with a printer engine for forming a toner image of each color. Since the configuration of the printer engine is common to the image stations 12K, 12C, 12M, and 12Y, here, the printer engine 13K of the image station 12K will be described as a representative.

  The printer engine 13K includes a photosensitive drum 21. The photosensitive drum 21 rotates counterclockwise in FIG. 2, and various known devices for forming an image by an electrophotographic process are provided around the photosensitive drum 21.

  First, the pre-charger 22 (charging device) performs a charging process for uniformly charging the surface of the photosensitive drum 21 to a constant potential. As the charging method, various methods such as a non-contact method such as corona discharge and a contact method such as a roller charging method can be used.

  The exposure device 23 optically writes an electrostatic latent image on the surface of the photosensitive drum 21 charged by the precharger 22. As a light source used for the exposure apparatus 23, a semiconductor laser, a gas laser, or the like can be used. When a semiconductor laser is used as the light source, generally, a known optical element (none of which is shown) such as a collimator lens, a polygon mirror, and an fθ lens is provided in the exposure device 23, and thereby the photosensitive drum 21. The surface is exposed and scanned.

  The developing device 24 performs a developing process for developing the electrostatic latent image on the surface of the photosensitive drum 21 with toner. In this example, the developing device 24 employs a two-component developing method, and toner used in the developing device 24 is supplied from a toner collector 25. The toner collector 25 is a container for a user to supply toner.

  The transfer charger 26 (transfer device) performs a transfer process of transferring the toner image formed on the surface of the photosensitive drum 21 onto the continuous paper P. As a transfer method, in addition to the corona transfer method, a roller transfer method, a belt transfer method, a pressure transfer method, an adhesive transfer method, and the like can be used. In this example, the transfer charger 26 is opposed to the highest position on the surface of the photosensitive drum 21 with the continuous paper P interposed therebetween. In the case of the surface printing apparatus 2, the surface on which the continuous paper P is printed is down. Then, the toner image is transferred to the surface, and in the case of the back surface printing device 3, the surface to be printed of the continuous paper P whose front and back surfaces are reversed by the front and back reversing device 5 is down and the toner image is transferred to the surface. In this example, a method for directly transferring the toner image on the photosensitive drum 21 onto the continuous paper P is illustrated. However, by interposing an image carrier such as an intermediate transfer belt in the middle, the photosensitive drum The toner image on 21 may be indirectly transferred to the continuous paper P.

  The transfer cleaner 27 (cleaning device) removes the toner remaining on the surface of the photosensitive drum 21 even after the transfer process. The toner removed by the transfer cleaner 27 is accommodated in the toner recovery bottle 29 via the toner recovery path 28. In this example, a toner collection bottle is used for each of the image stations 12K, 12C, 12M, and 12Y. However, a common toner collection bottle 29 may be used for the image stations 12K, 12C, 12M, and 12Y.

  The continuous paper P formed by sequentially superimposing the color toner images of K, C, M, and Y at the image stations 12K, 12C, 12M, and 12Y is positioned on the downstream side of the image station 12Y on the conveyance path. Fixing is performed by fixing devices 201 and 202 (FIG. 3). In the present embodiment, the following description will be made on the assumption that a heat roller contact method is used as the fixing method used in the fixing process.

(2) Fixing Device FIG. 3 is a schematic configuration diagram of the fixing device 201 (202) according to the first embodiment.

  A fixing device 201 (202) shown in FIG. 3 includes a fixing roller 211 as a heating member for a toner image and a pressure roller 212 as a pressure member.

  The fixing roller 211 shown in FIG. 3 is rotationally driven in a direction of an arrow at a predetermined speed, for example, a peripheral speed of 500 mm / sec, by a drive source (not shown).

  FIG. 4 is a schematic configuration diagram of the fixing roller 211 or the pressure roller 212. Since the fixing rollers 211 and 212 have substantially the same configuration, they are shown in the same figure.

  The fixing roller 211 shown in FIG. 4 includes a metal core 211a made of a cylindrical metal (made of aluminum in this embodiment) having an outer diameter of 74 mm, a thickness of 6 mm, and a length of 350 mm. On the metal core 211a, a silicone rubber (JIS-A hardness of 15 degrees in this embodiment) is coated with a thickness of 3 mm as a heat-resistant elastic layer 211b. On the heat-resistant elastic layer 211b, a fluororesin (PFA tube in this embodiment) is coated with a thickness of 100 μm as the heat-resistant release layer 211c in order to improve the releasability with the toner.

  Further, a halogen heater 213 with a rated power of 1500 W, for example, is disposed as a heating element inside the cored bar 211a of the fixing roller 211, and is heated from the inside so that the surface temperature of the fixing roller 211 becomes a predetermined target temperature. Yes.

  The surface temperature of the fixing roller 211 is detected by a thermistor 221 as temperature detecting means for a sheet passing portion of the fixing roller 211. Based on this detected temperature, the control unit 130 performs ON / OFF control of the halogen heater 213 to control the temperature to a predetermined target temperature, for example, 200 ° C.

  The fixing roller 211 shown in FIG. 4 is particularly employed in a color image forming apparatus, and can uniformly melt the surface of the toner image, so that a high-quality color image with uniform gloss can be obtained. Also in the black and white image forming apparatus, a solid black image and a uniform glossy high quality black and white image can be obtained. In this embodiment, the fixing roller 211 shown in FIG. 4 is used.

  The fixing roller of the black and white image forming apparatus often employs a configuration in which the heat-resistant elastic layer 211b is not provided and the release layer 211c is covered on the cored bar 211a from the viewpoints of cost and life. However, the fixing roller without the heat-resistant elastic layer 211b has a drawback in that minute contact unevenness occurs with the toner image, and therefore, minute gloss unevenness occurs and a uniform glossy image cannot be obtained.

  The pressure roller 212 shown in FIG. 3 is pressed to the fixing roller 211 with a predetermined pressure by a pressing means (not shown), forms the fixing roller 211 and the fixing nip portion N1, and rotates with the fixing roller 211 in the direction of the arrow. Is done. In this embodiment, the circumferential width of the fixing nip portion N1 is about 10 mm.

  The pressure row 212 shown in FIG. 4 includes a metal core 212a made of a cylindrical metal (made of stainless steel in this embodiment) having an outer diameter of 54 mm, a thickness of 3 mm, and a length of 350 mm. On the cored bar 212a, a silicone rubber (JIS-A hardness 20 degrees in this embodiment) is coated with a thickness of 3 mm as a heat-resistant elastic layer 212b. On the heat-resistant elastic layer 212b, a fluororesin (in this embodiment, a PFA tube) is coated with a thickness of 100 μm as the heat-resistant release layer 212c in order to improve the releasability with the toner.

  In addition, a halogen heater 214 having a rated power of 400 W, for example, is disposed as a heating element inside the metal core 212a of the pressure roller 212, and is heated from the inside so that the surface temperature of the pressure roller 212 becomes a predetermined temperature. Yes.

  The surface temperature of the pressure roller 212 is detected by a thermistor 222 as temperature detecting means for the sheet passing portion of the pressure roller 212. Based on this detected temperature, the control means 130 performs ON / OFF control of the halogen heater 214, thereby controlling the temperature to a predetermined target temperature, for example, 150 ° C.

(3) Double-sided image gloss uniformity means In the conventional electrophotographic apparatus, when the paper after fixing the first image forming apparatus is fixed in the second image forming apparatus, the recording paper is already fixed at a high temperature. Therefore, there is a problem that the image quality (glossiness) of the fixed image is not uniform in the first image forming apparatus and the second image forming apparatus.

  Further, the second image forming apparatus has a problem that a toner stick is generated when the paper temperature is excessively high and the paper temperature after paper discharge is not low.

  Therefore, in this embodiment, the fixing speed of the fixing device of the first image forming apparatus <the fixing speed of the fixing device of the second image forming apparatus according to the input paper basis weight and paper type. This is to reduce the gloss level difference on the first surface of the recording material during duplex printing in the image forming apparatus.

  More specifically, in the pressure roller as the pressure member, the temperature of the pressure roller 212 of the fixing device 201 of the first image forming apparatus 101 and the temperature of the fixing roller 211 of the fixing device 202 of the second image forming apparatus 102 are set to 200. The fixing property of the first surface of the recording material is secured by setting the temperature of 150 ° C. and the pressure roller 212 to 150 ° C. Then, the rotational speed of the fixing device 201 of the first image forming apparatus 101 is set to a peripheral speed of 500 mm / sec, and the rotational speed of the fixing apparatus 202 of the second image forming apparatus 102 is set to a similar peripheral speed of 500 mm / sec. Using an unfixed image in which toner is placed on a recording paper having a thickness of 0.045 mm, 0.097 mm, 0.281 mm, and 0.330 mm and having a toner amount of 1.1 g / cm 3, it passes through the first image forming apparatus 101 and the second image forming apparatus 102. Front and back printing was performed by paper. Then, the glossiness of the obtained image was measured. Regarding the glossiness, the ratio of the reflected light intensity to the incident light intensity was measured under the conditions of both incident angle and reflection angle of 60 ° C. Further, under the same conditions, image formation was performed only with the first fixing device 201, and the moisture content of the paper before and after fixing was measured. The results are shown in Table 1.

From the results shown in Table 1, it can also be seen from experimental results that the thinner the paper thickness, the greater the difference in glossiness between the front and back surfaces, that is, the first fixing device 201 and the second fixing device 202. This is presumably because the paper surface temperature is higher as the paper thickness is thinner when the image is fixed by the first fixing device 201. This can also be inferred from the change in the amount of water after exiting the first fixing device 201.

  Further, the state of the surface temperature of the recording paper fixed in the first image forming apparatus was verified for each paper thickness by calculating using a heat transfer simulation. The results are shown in FIGS. 5 (a) and (b). The surface temperature of the recording paper that has passed through the first image forming apparatus is 120 ° C. for a paper thickness of 0.045 mm and 80 ° C. for a paper thickness of 0.330 mm. It can be seen that the temperature difference when the recording paper enters greatly affects the image glossiness of the front and back surfaces.

  In order to solve the above problem, in this embodiment, as shown in Table 2, for each paper type, the rotational speed of the second fixing device 202 is amplified as compared with the rotational speed of the first fixing device 201. Similarly to the above, front and back printing was performed by passing paper through the first image forming apparatus 101 and the second image forming apparatus 102, and the glossiness of the obtained image was measured. The results are shown in Table 3.

  As shown in Table 3, for each paper type, the rotation speed of the second fixing device 202 is amplified as compared with the rotation speed of the first fixing device 201, so that the front and back surfaces, that is, the first fixing device 201 and the second fixing device are amplified. The glossiness with 202 could be made uniform.

  Further, as a reason for changing the rotation speed depending on the paper type, as shown in FIGS. 5A and 5B, when the paper passes through the nip portion N1 constituted by the fixing roller 211 and the pressure member 212, as shown in FIGS. It can be seen that the surface temperature of the paper thickness of 0.045 mm at the time (when 40 ms elapses) is about 40 ° C. higher than the paper thickness of 0.33 mm. This difference is sufficient as a factor for making the glossiness of both sides of the paper non-uniform, and therefore it is necessary to change the amplification rate of the fixing speed of the second image forming apparatus for each paper basis weight. If this embodiment is used, even if the paper basis weight is changed, the image glossiness on both sides can be kept uniform.

[Example 2]
<Paper type / basis weight detection means>
In the first embodiment, the paper type and the paper basis weight are input by the user, but in this embodiment, the paper surface property and the paper basis weight are accurately detected by providing the paper type basis weight detecting means. This is more preferable.

  FIG. 6 shows a schematic configuration diagram of the paper type basis weight detecting means arranged inside the paper feeding device 4. One recording sheet is picked up from the recording sheet P fed to the sheet feeding tray 605 by using the pickup roller 606. The picked-up recording paper is conveyed to the stage 603 through the conveyance path 604. A high-precision weight scale 607 is disposed below the stage 603 and measures the basis weight of one sheet of paper. The measured paper basis weight is input to the first and second image forming apparatuses.

  Further, on the stage 603, a light output device 601 and a light detector 602 are installed in the regular reflection direction. When the recording paper P is conveyed to the stage 603, the light output device 601 Light with a certain intensity is output. When the light output from the light output device 601 hits the surface of the recording paper P, the light is reflected / scattered by the surface shape of the paper, and the light detector 602 installed in the regular reflection direction is in the regular reflection direction. The intensity of the reflected light is detected. From the intensity ratio of the light reflected in the regular reflection direction, it is possible to detect whether the recording paper is a glossy paper having a high specularity or a plain paper having a low specularity. It is assumed that this series of operations is performed every time when the paper feed tray is opened and when it is started up.

[Example 3]
FIG. 7 shows a schematic diagram of a conveyance path between the fixing device and the transfer device. In the present embodiment, the rotation speed of the conveying belt 215 positioned between the fixing device 202 and the transfer device 12 in the second image forming apparatus 201 and the fixing device 202 in the second image forming apparatus 201 are described. Because the rotation speed is different, depending on the paper jam or the size of the recording paper, the downstream portion of the paper is being transferred and the upstream portion of the paper enters the fixing device 202, so that the image due to the change in the conveyance speed Problems such as flow may occur.

  For this reason, in this embodiment, the length La of the conveying belt 215 positioned between the fixing device 202 and the transfer device 12 satisfies La.> Lp with respect to the maximum size length Lp of the recording paper P. Thus, it is possible to prevent the fixing device 202 from being entered during the transfer in the transfer device 12 regardless of the size of the recording paper.

1-first image forming apparatus 1-second image forming apparatus 130-fixing control unit 201-first fixing apparatus 202-second fixing apparatus 211-fixing roller 212-pressure roller 213-fixing roller halogen heater 214-addition Halogen heater for pressure roller 215-External heating roller 216-Halogen heater for external heating 221/222 / 223-Temperature sensing element (thermistor)
501, 509-Heat generation layer 502, 508-Rubber layer 503, 507-PFA layer 504, 506-Contact heat resistance layer N1- Fixing nip N2- External heating nip K- Toner P- Recording material

Claims (3)

An electrostatic latent image is formed on the photosensitive member, the electrostatic latent image is visualized with a developing toner of a developing device using a two-component developing method, and the visualized toner image is transferred onto a recording medium by a transfer device. The toner image transferred onto the recording medium is fixed by a fixing device having a heating device and a temperature sensor for detecting the heating temperature to obtain a recorded image, and the toner remaining on the photoreceptor is cleaned. The two electrophotographic apparatuses having a series of electrostatic latent image recording processes to be prepared for the formation of the next electrostatic latent image are removed, and the fixing apparatus of the first apparatus and the fixing apparatus of the second apparatus are connected. A control mechanism that compares and controls the detected heating temperature and the setpoint temperature is provided, and after the paper that has been developed, fixed, and discharged by the first device is fed to the second device, it is then developed, fixed, and discharged. In a continuous-type electrophotographic apparatus that continuously prints on paper,
A basis weight / paper type detection means for detecting the basis weight and paper type of the print medium, which is located upstream of the first printing apparatus in the transport path of the print medium;
Control means for amplifying the fixing speed of the fixing device of the second apparatus according to the type of print medium as a result of detection by the basis weight / paper type detection means,
An electrophotographic apparatus.   2. The electrophotographic apparatus according to claim 1, wherein the fixing device is a two-roll type fixing system including a heating roll and a pressure roll. The transport path length La between the transfer device and the fixing device of the first and second printing apparatuses satisfies La> Lp with respect to the maximum length Lp of the printing medium. 2. The electrophotographic apparatus according to 1.