JP2012194342A - Sheet separation device, fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust an injection condition of compressed gas for separating a sheet member and a fixing member so as to match with a required condition.SOLUTION: A sheet separation device is disposed on a fixing device which carries a sheet member P carrying unfixed toner with a nip portion N formed by a fixing belt 61 and a pressurizing roller 62, and fixing that. A nozzle member 72 for jetting compressed air jets the compressed air from a carrying upstream direction of the sheet member P toward the nip portion N, thereby assisting the separation of the fixing member and the sheet member. The sheet separation device is provided with two solenoid valves 88 and 89 controlling the compressed air to be introduced to the nozzle member 72, and a fluid control valve 87 for reducing at least either one of pressure or flow rate of the compressed air on at least the one solenoid valve 88 of the solenoid valves. A solenoid valve control device 91 selects one of the solenoid valves, and drives that synchronously with a carrying timing of the sheet member.

Description

  The present invention relates to a sheet separating apparatus, a fixing apparatus, and an image forming apparatus, and more particularly to a sheet separating apparatus, a fixing apparatus, and an image forming apparatus that discharge a compressed gas to separate a sheet from a fixing member.

  An electrophotographic image forming apparatus includes a fixing device that heats and presses a sheet member such as a sheet on which a toner image is transferred. A nip portion is formed by a fixing roller incorporating a heat source such as a halogen heater and a pressure roller in contact with the fixing roller as the fixing device, and the sheet member on which the unfixed toner image is transferred is sandwiched between the nip portion and conveyed. There is a heat roller fixing type in which an unfixed toner image is fixed on a sheet member.

  In addition, a ring-shaped fixing belt is hung between a heating roller incorporating a halogen heater or the like and a fixing roller disposed adjacent to the heating roller, and a pressure roller that contacts the fixing roller via the fixing belt. And a belt fixing system in which a nip portion is formed with the fixing belt, and a sheet member on which an unfixed toner image is transferred is sandwiched and conveyed to the nip portion to fix the unfixed toner image on the sheet member. The

  Such a fixing belt type fixing device has an advantage that since the heat capacity of the fixing belt is small, the warm-up time can be shortened and the power can be saved.

  In the fixing device, since the toner image fused to the sheet member comes into contact with the fixing roller or the fixing belt, the fixing roller or the fixing belt is coated on the surface with a fluorine resin having excellent releasability, and the separation claw Is used to separate the sheet member.

  The major drawback of using a separation claw is that the separation claw comes into contact with the fixing roller or the fixing belt, so that the surface of the fixing roller or the fixing belt is likely to have nail marks (claw scratches). This means that streaks appear on the output image of the sheet member.

  In general, in the case of a monochrome image forming apparatus, a fixing roller having a metal roller surface coated with a silicone resin is used. However, in the case of a color image forming apparatus, in order to improve the color developability, the surface layer is a silicone rubber coated with fluorine (generally using a PFA tube of about several tens of microns) or the surface of the silicone rubber. Use oil coated on the surface.

  The fixing roller having such a configuration has a problem that the surface layer is soft and easily damaged. When the surface layer is scratched, streak-like scratches are formed on the fixed image. Therefore, the color image forming apparatus now uses almost no contact means such as a separation claw, and most performs non-contact separation.

  In the non-contact separation, if the adhesive force between the toner and the fixing roller is high, the sheet member after fixing is wound around the roller, so that a winding jam easily occurs. In particular, in color image formation, a number of toner layers are formed, and the adhesive strength is increased, so that winding jam is likely to occur.

Therefore, the following (1) to (3) are mainly employed for sheet separation in the current color image forming apparatus.
(1) Non-contact using a separation plate arranged in parallel in the longitudinal direction and the width direction of the fixing roller or fixing belt by opening a minute gap (about 0.2 mm to 1.0 mm) between the fixing roller and the fixing belt. Separation plate method.
(2) A non-contact separation claw method using a separation claw having a small gap (about 0.2 mm to 1.0 mm) between the fixing roller and the fixing belt and arranged at a predetermined interval.
(3) A self-stripping method in which the sheet member is naturally peeled by the stiffness of the sheet member and the elasticity of the curved portion of the fixing roller and fixing belt.

  However, in any of the above methods (1) to (3), since a gap with the sheet guide plate to the fixing outlet is open, when passing a sheet member with thin paper or a small margin at the leading edge, or for a photograph or the like When passing a sheet member on which a solid image is formed, the sheet member passes through the gap while being in close contact with the fixing roller or the fixing belt, and a paper wrap jam occurs or a jam occurs when it hits a separation plate or a separation claw. May occur.

  Therefore, in order to reliably separate the sheet member in a non-contact manner, a technique for blowing a compressed gas such as air to a sheet separation position has been proposed and used (for example, Patent Document 1, Patent Document 2, and Patent Document 3). , Patent Document 4, Patent Document 5, and Patent Document 6). In these methods, compressed air is blown between the toner image after fixing of the sheet member and the fixing member to forcibly separate the sheet member from the fixing member.

  However, there is the following problem when separating the sheet member by blowing compressed air between the toner image after fixing of the sheet member and the fixing member. FIG. 5 is a photograph showing a separation state of the sheet member by the compressed gas. FIG. 5 shows a state in which the sheet member P is separated from the fixing member 130 by the compressed air flow A. Reference numeral 140 denotes a pressure roller, and 150 denotes a nozzle member that blows out the compressed air flow A. In the figure, a broken line is added to the outline of the sheet member P.

  As shown in FIG. 5, when the compressed air flow A hits the sheet member P on which the toner is thermocompression bonded, the compressed air flow A is preferentially separated from the hit and the compressed air flow A is not hit. Separated with a delay. For this reason, it turns out that the edge part of the sheet | seat member P is wavy. Such a phenomenon becomes particularly noticeable when a large amount of toner adhered, represented by a recent color electrophotographic toner.

  In addition, the toner image that is exposed to the compressed air flow A in the sheet member P is cooled. Due to both of these actions, when a sheet separation device using compressed air is used, a difference in the amount of heat applied to the toner image occurs, and there is a difference in gloss between the toner image where it is exposed and where it is not. , May cause image disturbance.

  FIG. 6 is a schematic diagram of an image in which a gloss difference is generated in the toner image. In the toner image on the sheet member P in FIG. 6, there is a difference in gloss in the toner image between the region T1 where the compressed air flow A acts and the region T1 separated earlier and the region T2 where the compressed air flow 120 does not act and is separated later. Has occurred.

  When separation is performed in this way, the greater the pressure and flow rate of compressed air, the greater the force acting on the separation. For example, a thinner sheet member, an image with a large amount of toner, or an image with a small front end margin can be separated. Is possible.

  Therefore, generally speaking, when separating a sheet member using compressed gas, there are two requirements of reducing the margin at the tip of the image and adhering a large amount of toner, and improving gloss unevenness of the image. Is a conflicting relationship. Therefore, it is desirable to perform separation by setting the pressure and flow rate of compressed air according to the type of sheet member to be printed and the image area.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet separating apparatus, a fixing apparatus, and an image forming apparatus capable of adjusting a jetting condition of a compressed gas for separating a sheet member and a fixing member to match a desired condition. And

  Therefore, the present invention

  The invention of claim 1 that solves the above-described problem is provided with a fixing member that is a rotating body having a heating means, and a pressing member that is pressed against the fixing member, and is formed by the two members. A fixing member that conveys a sheet member carrying unfixed toner and fixes the toner image on the sheet member, and includes a compressed gas generating means and a nozzle member that ejects compressed gas. In the sheet separating apparatus for assisting the separation of the fixing member and the sheet member by injecting the compressed gas from the upstream direction of the sheet member toward the nip portion, the compressed gas generating means includes a plurality of electromagnetic valves. A fluid control valve connected to at least one solenoid valve of the solenoid valve to reduce at least one of pressure and flow rate of the compressed gas, and one solenoid valve from the plurality of solenoid valves Select a sheet separating apparatus characterized by comprising: a control means for driving taking conveyance timing and synchronization of the sheet member.

  Similarly, the invention of claim 2 is the sheet separating apparatus according to claim 1, wherein the fluid control valve is a flow control valve.

  Similarly, the invention of claim 3 is the sheet separating apparatus of claim 2, wherein the flow control valve is a throttle valve.

  Similarly, the invention of claim 4 is the sheet separating apparatus of claim 1, wherein the fluid control valve is a pressure reducing valve.

  Similarly, the invention according to claim 5 is the sheet separating apparatus according to claim 4, wherein the pressure reducing valve is a pressure reducing valve with a relief.

  Similarly, the invention of claim 6 is characterized in that, in the sheet separating apparatus of claim 1, a pressure reducing valve is arranged in series with the fluid control valve.

  Similarly, the invention of claim 7 is directed to a sheet separating apparatus according to any one of claims 1 to 6, a fixing member that is a rotating body having a heating means, and a pressure member that is pressurized by the fixing member. And a fixing device.

  Similarly, the invention of claim 8 is an image forming apparatus comprising: the fixing device according to claim 7; and image forming means for forming a toner image on a sheet carried into the fixing device.

  According to the present invention, the fluid control valve is connected to at least one of the plurality of solenoid valves, and the solenoid valve is selected and driven by the control means. The pressure and flow rate of compressed air corresponding to the type of sheet member to be printed and the image area can be set to the optimum values.

1 is a schematic cross-sectional view illustrating a structure of an image forming apparatus according to an embodiment. 1 is a schematic diagram illustrating a fixing device according to an embodiment. It is a circuit diagram which shows the compressed air supply circuit which concerns on an Example. It is a block diagram which shows the control system of the sheet separation apparatus which concerns on an Example. It is a photograph which shows the separation state of the sheet member by compressed gas. FIG. 6 is a schematic diagram of an image in which a gloss difference has occurred in a toner image.

  In the sheet separating apparatus according to the embodiment, a fluid control valve is connected to at least one of a plurality of solenoid valves, and the solenoid valve to be used is selected by the control means so that the injection condition of the compressed gas can be changed. . Thereby, the electromagnetic valve to be driven can be selected, and the strength of the compressed gas used for separating the sheet member, that is, the magnitude of the force exerted on the separation of the sheet member by the compressed gas can be selected.

  Moreover, the sheet separation apparatus according to the embodiment connects a flow control valve to the electromagnetic valve. Thereby, the flow rate can be reduced without causing a pressure drop of the compressed air.

  Moreover, the sheet separating apparatus according to the embodiment connects a throttle valve to the electromagnetic valve. As a result, the flow rate can be reduced without causing a pressure drop of the compressed air, which can be realized at low cost.

  Moreover, the sheet separation apparatus according to the embodiment connects a pressure reducing valve to the electromagnetic valve. As a result, the pressure can be reduced, and the flow rate can be reduced simultaneously with the pressure.

  Moreover, the sheet separation apparatus according to the embodiment has a relief pressure reducing valve connected to a solenoid valve. As a result, the pressure can be reduced, and the flow rate can be reduced simultaneously with the pressure.

  Moreover, the sheet separation apparatus according to the embodiment uses a flow control valve and a pressure reducing valve in series between the electromagnetic valve and the nozzle. As a result, both the flow rate and pressure of the compressed gas can be controlled to desired values.

  Furthermore, the sheet separating apparatus according to the embodiment can select an electromagnetic valve to be controlled based on the paper type of the sheet member acquired by the image forming apparatus and the printing information of the image area.

  Hereinafter, a fixing device and an image hair device according to an embodiment of the present invention (hereinafter simply referred to as an embodiment) will be described. FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment. In the figure, reference numeral 100 denotes a copying apparatus main body, 200 a paper feed table, 300 a scanner, 400 an automatic document feeder (ADF), and 500 an exposure apparatus. The copying apparatus main body 100 is placed on a paper feed table 200, a scanner 300 is mounted on the copying apparatus main body 100, and an ADF 400 is further mounted thereon.

  The copying machine main body 100 is provided with an endless belt-like intermediate transfer member 10 in the center and is wound around three support rollers 14, 15 and 16 so that it can be rotated and conveyed clockwise in the drawing. In this example, an intermediate transfer body cleaning device 17 for removing residual toner remaining on the intermediate transfer body 10 after image transfer is provided on the left side of the second support roller 15 among the three support rollers.

  Further, yellow, cyan along the transport direction of the intermediate transfer body 10 so as to be positioned on the intermediate transfer body 10 between the first support roller 14 and the second support roller 15 of the three support rollers. The tandem image forming device 20 is configured by arranging four image forming units 18 of magenta and black side by side. An exposure device 21 is provided above the tandem image forming device 20 as shown in the figure.

  On the other hand, a secondary transfer device 22 is provided on the opposite side of the tandem image forming device 20 with the intermediate transfer member 10 interposed therebetween. In the illustrated example, the secondary transfer device 22 is configured such that a secondary transfer belt 24, which is an endless belt, is hung between two rollers 23, and is attached to a third support roller 16 via an intermediate transfer body 10. The secondary transfer belt 24 is disposed so as to be pressed against it, and the image on the intermediate transfer body 10 is transferred to a sheet as a transfer material.

  Next to the secondary transfer device 22, a fixing device 60 for fixing the transferred image on the sheet is provided. The fixing device 60 is configured by pressing a pressure roller 62 against a fixing belt 61 that is an endless belt. The secondary transfer device 22 described above has a sheet transport function for transporting the sheet after image transfer to the fixing device 25. Of course, a transfer roller or a non-contact charger may be disposed as the secondary transfer device 22, but in such a case, it is difficult to provide this sheet conveyance function together.

  In the example shown in the figure, a sheet for reversing the sheet in order to record an image on both sides of the sheet in parallel with the tandem image forming device 20 described above below the secondary transfer device 22 and the fixing device 25. A reversing device 28 is provided.

  The operation when making a copy using this color electrophotographic apparatus will be described. The document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and the document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.

  When a start switch (not shown) is pressed, when a document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. When this happens, the scanner 300 is immediately driven to cause the first traveling body 33 and the second traveling body 34 to travel. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is also rotated by a drive motor (not shown) and the other two support rollers are driven to rotate. 10 is rotated and conveyed. At the same time, the photoconductors 40K, 40Y, and 40C are rotated by the individual image forming means 18, and black, yellow, and magenta are respectively formed on the photoconductors 40K, 40Y, 40C, and 40M that are exposed by the exposure device 500 to form latent images. , Forming a cyan monochrome image. Then, along with the conveyance of the intermediate transfer member 10, the single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10.

  On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selected and rotated, and a sheet is fed out from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages and separated. The paper is separated one by one by the roller 45 and is put into the paper feed path 46, conveyed by the transport roller 47, guided to the paper feed path 48 in the copying apparatus main body 100, and abutted against the registration roller 49 to be stopped. When paper is fed from the manual feed tray 51, the paper feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, and put into the manual feed path 53. Stop by hitting.

  Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet.

  The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 60. After fixing the transferred image by applying heat and pressure by the fixing device 60, the sheet is switched by the switching claw 55 and discharged. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.

  On the other hand, the intermediate transfer member 10 after the image transfer is removed by the intermediate transfer member cleaning device 17 to remove residual toner remaining on the intermediate transfer member 10 after the image transfer, so that the tandem image forming device 20 can prepare for another image formation.

  Next, the fixing device according to the embodiment will be described. FIG. 2 is a schematic diagram illustrating the fixing device according to the embodiment. The fixing device 60 according to the embodiment is a belt fixing device. In the fixing device 60, a fixing belt 61 as a fixing member is hung on a fixing roller 64 as a driving roller and a heating roller 65 as a driven roller, and rotates.

  The pressure roller 62 is provided relative to the fixing roller 64 via the fixing belt 61, and the pressure roller 62 is pressed against the fixing roller 64 via the fixing belt 61 by a pressure mechanism (not shown). . A fixing heater 66 as a heat source is provided inside the heating roller 65, and the heating roller 65 is heated by the fixing heater 66 and the fixing belt 61 is heated by the heating roller 65. The fixing belt 61 rotates when the fixing roller 64 is rotationally driven by a drive mechanism (not shown), and the pressure roller 62 rotates with the fixing belt 61. A driving force may be applied to the pressure roller 62.

  The surface temperature of the fixing belt 61 is detected by a temperature detection element (not shown), and a temperature control unit (not shown) controls the fixing heater 66 based on the output value of the temperature detection element so that the surface temperature of the fixing belt 61 becomes a predetermined set temperature. To control.

  The unfixed sheet member P is carried into the fixing device 60, passes through the nip N between the fixing belt 61 and the pressure roller 62, and is formed by the fixing belt 61 and the pressure roller 62 that are controlled to a predetermined temperature. The toner image T is melted and fixed at the nip portion N and sent out of the apparatus main body. Although the pressure roller 62 is used as the pressure member, a pressure belt or the like may be used.

  In the embodiment, a tension roller 63 for holding the belt tension is provided outside the fixing belt 61. The position of the tension roller 63 may be inside the fixing belt 61.

  In the fixing device 60 according to the embodiment, a nozzle member 72 is disposed in the vicinity of the exit of the nip portion N. Note that the nozzle member 72 depicted in FIG. 3 is shown schematically only at the tip. Further, the nozzle member 72 can be juxtaposed with a non-contact separation claw (sometimes referred to as a separation plate).

  A compressed air flow A controlled by a compressed gas supply means (not shown) and an electromagnetic valve is jetted toward the nip portion N through a pipe line 72 a in the nozzle member 72. The leading end of the sheet member P is forcibly separated from the fixing belt 61 by the flow of the compressed air.

  Next, a compressed air supply circuit which is a compressed gas supply unit of the sheet separating apparatus according to the embodiment will be described. FIG. 3 is a circuit diagram illustrating a compressed air supply circuit according to the embodiment. In FIG. 3, each member other than the fixing device 60 is drawn according to JIS B 0125.

  In the embodiment, the compressed air supply circuit includes a compressor 81, an air filter 83, a first electromagnetic valve 84, a pressure adjustment valve 85, a fluid control valve 87, and a third electromagnetic valve 89. An air filter 83 is disposed downstream of the compressor 81 that is a source of compressed air for draining. The pipe 82 downstream from the compressor 81 is desirably downward. The air filter 83 removes foreign matter (dust) present in the compressed air and removes moisture generated in the piping. Here, if a large-capacity air filter is used, it also serves as a buffer for compressed air injection, enabling stable compressed air injection. Although not shown, an air tank dedicated to the buffer function may be arranged downstream of the air filter 83.

  A first electromagnetic valve 84 is connected to the air filter 83. The first electromagnetic valve 84 has a function of discharging the exhaust pressure and drainage in the circuit. When the operation of the machine is stopped, the first electromagnetic valve 84 is opened to exhaust the inside of the circuit and air. Drain accumulated in the filter is also discharged. The drain is received by the evaporating dish 90.

  A pressure adjusting valve (relief valve) 85, a second electromagnetic valve 88, and a third electromagnetic valve 89 are connected to the air filter 83. By adjusting the pressure adjusting valve 85, the pressure during the compressed gas injection can be controlled. By adjusting the pressure adjustment valve 85, the compressor 81 is controlled so that the air filter 83 becomes a predetermined pressure during operation.

  A silencer 86 is connected to the pressure regulating valve 85 to reduce the sound of compressed air that escapes from the pressure regulating valve 85. A fluid control valve 87 is disposed downstream of the second electromagnetic valve 88, and compressed air from the fluid control valve 87 is supplied to the nozzle member 72. Each fluid control valve can be disposed as the fluid control valve. The type of fluid control valve will be described later.

  In the embodiment, a second electromagnetic valve 88 and a third electromagnetic valve 89 are connected in parallel, and compressed air is also supplied to the nozzle member 72 from the third electromagnetic valve 89. The second solenoid valve 88 and the third solenoid valve 89 are controlled exclusively.

  In the sheet separating apparatus according to the embodiment, the third electromagnetic valve 89 is not connected to a fluid regulating valve or the like. The compressed gas ejection condition when the third electromagnetic valve 89 is driven is herein referred to as “first injection condition”. When the second electromagnetic valve 88 is driven, the compressed gas adjusted by the fluid control valve 87 is injected from the nozzle member 72. The compressed gas ejection condition from the fluid control valve 87 is referred to as “second injection condition”.

  Since the fluid regulating valve is not connected to the third electromagnetic valve 89, either the pressure or flow rate of the gas injected from the nozzle member 72 is larger than when the second electromagnetic valve 88 is selected. That is, either the pressure or flow rate of the compressed gas is larger in the “first injection condition” than in the “second injection condition”.

  Next, a control system of the sheet separating apparatus according to the embodiment will be described. FIG. 4 is a block diagram illustrating a control system of the sheet separating apparatus according to the embodiment.

  The first solenoid valve 84, the second solenoid valve 88, and the second solenoid valve 88 are connected to a solenoid valve control device 91 that is a control means. The electromagnetic valve control device 91 selects one electromagnetic valve from the second electromagnetic valve 88 and the third electromagnetic valve 89 and drives it in synchronization with the conveyance timing of the sheet member. The electromagnetic valve control device 91 is connected to an image forming apparatus control unit 110 that controls the copying apparatus main body 100 and an input means pressure 111 such as an input panel. Based on the operator's instruction from the means pressure 111, the operation of the second solenoid valve 88 and the third solenoid valve 89 is switched. That is, the solenoid valve control device 91 selects the pressure and flow rate of the compressed air according to the type of sheet member and the image area during printing, and selects “first injection condition” and “second injection condition”. To do.

  Next, the fluid control valve 87 will be described. As for the pressure and flow rate conditions of the compressed gas, the correlation between the pressure and flow rate and the pattern of separation of the sheet member has an interaction due to surrounding shields etc. Therefore, it is necessary to determine the behavior of the sheet member during actual separation. However, since the pressure and flow rate tend to be given to the paper behavior, the design of the pressure and flow rate can be determined by considering the behavior of the sheet member and uneven gloss.

  An arrow B in FIG. 2 indicates a direction in which the sheet member is separated. In order to move the sheet member quickly in this separating direction, the pressure is increased. On the other hand, when it is desired to move the sheet member slowly, the pressure is lowered. This is because when the pressure is high, the force acting on the sheet member increases. In addition, when the pressure is high, the difference in separation time between the working part and the non-working part of the compressed gas also increases. When it is desired to increase the momentum of the sheet member in the separation direction in the B direction, the flow rate is increased. If you want to reduce the momentum, decrease the flow rate. When the flow rate is large, the layer of compressed gas flow becomes large and the sheet member moves along the expected flow. Therefore, when the flow layer is large, the momentum of the sheet member also increases.

  The fluid control valve 87 described above includes a flow rate control valve that makes the flow rate constant and a pressure control valve that makes the pressure constant. Here, the flow control valve is classified into a speed control valve (speed controller) and a throttle valve. The speed control valve can control the flow rate to be constant without causing pressure fluctuation of the compressed gas (see JIS B 8376).

  Further, the pressure reducing valve is a pressure control valve and can reduce the pressure, but at the same time the flow rate is reduced. The pressure reducing valve with relief does not lead to saving of compressed gas because the compressed gas is released to reduce pressure, but it is inexpensive because of its simple structure (for details of the pressure reducing valve and pressure reducing valve with relief, refer to JIS B 8372 1). reference).

  When a speed control valve is used as the fluid control valve 87, there is no pressure drop, and only the flow rate is lowered. Therefore, the movement distance can be reduced without reducing the movement speed in the separation direction of the sheet member, and the sheet member Avoid excessive exercise.

  On the other hand, when a throttle valve is used as the fluid control valve 87, the pressure may be higher than when a speed control valve is used. However, since the flow rate can be reduced constantly, the movement distance of the sheet member in the separation direction can be reduced.

  The throttle valve is inexpensive because it has a simple structure (orifice structure) in which the effective cross section in the pipe is partially throttled. Further, the two types of flow control valves may be arranged at a location indicated by reference numeral 90 upstream from the electromagnetic valve. In 87, when a pressure reducing valve is used, the pressure decreases and the flow rate also decreases. Therefore, both the movement speed and the movement distance of the sheet member can be reduced. The effect of using a relief pressure reducing valve as the fluid control valve 87 is the same.

  With respect to the pressure reducing valve, if the pressure is placed at the position of the reference numeral 90 on the upstream side of the second electromagnetic valve 88, the pressure before the second electromagnetic valve 88 is reduced by the pressure reducing valve. Only when is opened, the pressure reducing valve works.

  The pressure reducing valve is preferably disposed at the position of the third electromagnetic valve 89. When the flow control valve and the pressure reducing valve are arranged in series at the position of the third electromagnetic valve 89, both the flow rate and the pressure can be set to desired values. However, both a flow control valve and a pressure reducing valve are required, resulting in high costs.

  In the above embodiment, the belt fixing device has been described as an example of the fixing device. However, the fixing device is not limited to the belt fixing device, and there are two fixing members including a fixing member having a heating source and a pressing member pressed against the fixing member. It may be a so-called roller fixing device composed of a pair of rollers.

  Moreover, although the said Example demonstrated the case where the two solenoid valves which send compressed air to the nozzle member 72 were demonstrated, the number of the solenoid valves which send compressed air to the nozzle member 72 shall be three or more, and the compressed air from each solenoid valve is set. The flow rate and pressure can be made different. By increasing the number of solenoid valves, fine adjustments can be made according to printing conditions.

DESCRIPTION OF SYMBOLS 10 Intermediate transfer body 14 1st support roller 15 2nd support roller 16 3rd support roller 17 Intermediate transfer body cleaning device 18 Image forming means 20 Tandem image forming device 21 Exposure device 22 Secondary transfer device 23 Roller 24 Secondary Transfer belt 25 Fixing device 28 Sheet reversing device 30 Document base 32 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Sensors 40K, 40Y, 40C Photoconductor 42 Paper feed roller 43 Paper bank 44 Paper feed cassette 45 Separating roller 46 Feeding path 47 Conveying roller 48 Feeding path 49 Registration roller 50 Feeding roller 51 Tray 52 Separating roller 53 Feeding path 55 Switching claw 56 Discharging roller 57 Discharging tray 60 Fixing device 61 Fixing belt 62 Pressure roller 63 Tension roller 72 Nozzle member 72a Pipe line 81 Compressor 82 pipe 83 air filter 84 first solenoid valve 85 a pressure regulating valve (relief valve)
86 Silencer 87 Fluid control valve 88 Second solenoid valve 89 Third solenoid valve 90 Evaporating dish 91 Solenoid valve control device (control means)
DESCRIPTION OF SYMBOLS 100 Copying device main body 64 Fixing roller 65 Heating roller 66 Fixing heater 120 Compressed air flow 130 Fixing member 140 Reference numeral 200 Feeding table 300 Scanner 400 Automatic document feeder 500 Exposure device

JP 51-104350 A Japanese Patent No. 2876217 Japanese Patent Laid-Open No. 6434191 JP 2007-187715 A JP 2007-240920 A JP 2008-102408 A JP 2009-31759 A

Claims (8)

A fixing member, which is a rotating body having a heating unit, and a pressure member formed by pressing the fixing member are provided, and a sheet member carrying unfixed toner is conveyed at a nip formed by the two members. And a fixing device for fixing the toner image to the sheet member, comprising a compressed gas generating means and a nozzle member for injecting the compressed gas, and a nip portion from the nozzle member for conveying the compressed gas from the upstream direction of conveyance of the sheet member In the sheet separating apparatus for assisting the separation of the fixing member and the sheet member by spraying toward
The compressed gas generating means includes a plurality of solenoid valves,
A fluid control valve connected to at least one solenoid valve of the solenoid valve to reduce at least one of pressure and flow rate of the compressed gas;
Control means for selecting one solenoid valve from the plurality of solenoid valves and driving in synchronization with the conveyance timing of the sheet member;
A sheet separating apparatus comprising:   The sheet separation apparatus according to claim 1, wherein the fluid control valve is a flow control valve.   The sheet separation apparatus according to claim 2, wherein the flow control valve is a throttle valve.   The sheet separating apparatus according to claim 1, wherein the fluid control valve is a pressure reducing valve.   The sheet separating apparatus according to claim 4, wherein the pressure reducing valve is a pressure reducing valve with a relief.   The sheet separating apparatus according to claim 1, wherein a pressure reducing valve is arranged in series with the fluid control valve.   A sheet separating apparatus according to any one of claims 1 to 6, a fixing member that is a rotating body having a heating unit, and a pressing member that is pressed against the fixing member. Fixing device.   An image forming apparatus comprising: the fixing device according to claim 7; and an image forming unit that forms a toner image on a sheet carried into the fixing device.