JP5353459B2 - Air discharge device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and low-cost air discharge device for driving an air pump by a one-way rotation of a motor wherein an excessive load is not applied to a motor shaft. <P>SOLUTION: A crank disk 81 is rotated by a timing belt which is not illustrated in the figure from the motor 110. A crank lever 86 is pivoted for a crank disc 81 and a piston 55 is reciprocated in a cylinder 53 in a right-and-left direction of the figure as the crank disc 81 rotates. A filler 82 is arranged to project on the crank disk 81 and a sensor 95 for detecting the filler 82 is arranged. The filler 82 is detected by the sensor 95 when a driving signal is input to the motor and the crank disk 81 rotates once and thus the motor 110 is stopped. Hence, rotation and stop can be repeated without a clutch by the one-way rotation of the motor 110. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an air discharge device that discharges pressurized air and an image forming apparatus including the air discharge device.

  An air supply device or an air supply system for pressurizing and supplying air used in various industrial devices and production facilities is well known. Conventional general air supply systems require a compressor, an air tank, a solenoid valve, an air nozzle, a driving source for driving the compressor, a pressure sensor for pressure control, and the like.

  The conventional air supply device (air supply system) configured in this way has to be large. In addition to the size, it takes time (for example, about 1 minute) to compress the air before the high-pressure air is obtained, and the compressor cannot be used immediately after starting the apparatus. A solenoid valve or the like is required and there are many overall components, which is very expensive. The compressor operating noise is noisy. Energy saving is difficult because the device configuration is large and consumes a large amount of power. The current situation is that its use is limited to business machines such as industrial machines and production facilities.

  By the way, in the field of image forming apparatuses, there are some that use air for paper separation and paper conveyance in a paper feeding unit or paper separation (peeling) in a fixing unit (for example, Patent Document 1 and Patent Document 2). As described above, the conventional air supply device (air supply system) is large, and the image forming apparatus using it is limited to a large business printing machine operated by a specialized operator, and is used for copying in general offices. It is difficult to employ air separation and air conveyance in machines and printers.

  In order to realize a small and low-cost air discharge device using a small air pump having a cylinder and a piston that reciprocates in the cylinder, it is practical to use a small motor as a drive source for driving the piston. In order to reciprocate the piston by a small motor, there are a method of reciprocating the piston by forward and reverse rotation of a pulse motor (stepping motor) and a method of reciprocating the piston by a crank mechanism using a DC motor.

  However, when using a pulse motor, the motor rotates in the reverse direction when the piston returns from top dead center (maximum compression position) when the rotation direction of the motor in the compression process is set to normal rotation. During the compression process, a large load is applied to the motor due to the compression and repulsive force of the air.When the air is completely discharged, the load decreases rapidly, and when returning from the top dead center, the motor rotates in reverse and the motor shaft A reverse load is applied.

  When the reverse rotation of this load is repeated at a high speed (for example, at least 100 reciprocations per minute), the motor shaft is subjected to a switching load (reverse load) for switching between the air compression load and the rotation direction, thereby causing motor vibration and noise. As a result, there is a problem that the starting torque is increased, and as a result, the motor life is shortened.

  When a DC motor and a crank mechanism are used, the motor is only normally rotated (one-way rotation), and the above-described problem does not occur when a pulse motor is used, but a piston is moved and stopped using a one-rotation clutch. In the configuration in which the crankshaft rotates once and the piston reciprocates once when the clutch is connected, in the continuous operation of the piston, for example, 100 reciprocations per minute or more, the clutch is connected (connected). Since the clutch is connected at a high speed, a large load is applied to the clutch, and the coupling friction force on the clutch shaft is reduced by repeated operations of several tens of thousands of times, and the piston cannot be pushed completely (the clutch reaches the end of its life). .

  An object of the present invention is to solve the above-described problems in an air supply device configured to drive an air pump by a small motor, and to provide a small, low-cost and long-life air discharge device.

According to the present invention, there is provided an air pump having a cylinder and a piston that reciprocates in the cylinder, and the piston is reciprocated through a crank mechanism from a motor that is a driving source to drive the air pump and pressurize. In the air discharge device for discharging the air that has been discharged at a predetermined timing, a detection means for detecting the position of the piston is provided, the motor is rotating in one direction, and the motor is rotated and stopped based on the detection signal of the detection means The air pump performs a process of air compression, air discharge, and air suction between one rotation of the crank mechanism and one reciprocation of the piston, and is provided at the air discharge port of the air pump. An opening / closing member that opens or closes the outlet, and is mechanically connected to both the piston and the opening / closing member; There is resolved by including a switching mechanism that switches the open state the closing member when the to reach the predetermined point in compressing movement has reached the predetermined point while maintaining the closing member in the closed state The

  Further, the crank mechanism has a crank disk rotatably supported and a crank lever with one end being eccentrically pivoted to the crank disk, and the detecting means is to be detected provided on the crank disk. It is preferable to detect the position of the piston by detecting the member.

The motor is preferably a stepping motor.
The detection means is preferably an optical sensor.

Further, according to the present invention, there is provided a heating rotating member that heats a recording paper and a pressure rotating member that abuts against the surface of the heating rotating member to form a nip portion. An image forming apparatus including a fixing device having a separating unit that separates recording paper from a member, comprising the air discharge device according to any one of claims 1 to 4 , wherein the separating unit is provided from the air discharge device. This is solved by an image forming apparatus that supplies air to the apparatus.

According to the air discharge device of the present invention, the motor as the driving source is unidirectionally rotated, and the rotation and stop of the motor are controlled based on the detection signal of the detection means, and one rotation of the crank mechanism and one reciprocation of the piston are performed. Since the air pump performs the steps of air compression, air discharge, and air suction, there is no switching load (reverse load) when switching the motor rotation direction, and motor vibration, noise, startup torque increase, etc. Therefore, it is possible to prevent the motor life from being lowered and to realize a long-life air discharge device.
In addition, the air pressure can be increased in the cylinder, and the air with the increased pressure can be discharged at once. Thereby, an air tank and a solenoid valve become unnecessary.

  In addition, since driving and stopping can be repeated without using a single-rotation clutch, there is no problem that the clutch reaches the end of its life due to a large load when the clutch is engaged, and an air discharge device that has a long life can be realized in this respect. Can do.

With the configuration of the second aspect, the piston position can be reliably detected with a simple configuration.
With the configuration of claim 3, by using the stepping motor, the rotation speed can be freely set according to the air discharge cycle.

  With the configuration of the fourth aspect, the piston position can be detected with high accuracy and low cost.

According to the image forming apparatus of the fifth aspect , by using a small and low-cost air discharge device as an air supply source to the separation unit in the fixing device, air separation can be performed even in an image forming device of a size and price used in an office or the like. Can be used for reliable paper separation.

It is a front view which shows one Example of the air discharge apparatus which concerns on this invention. It is a plane sectional view of the air discharge device. It is a longitudinal cross-sectional view from a side surface direction. The longitudinal cross-sectional view from the front direction shows the state where the piston has moved to the expanded position (bottom dead center). A state in which the piston has moved to the compression position (top dead center) is shown in a longitudinal sectional view from the front direction. It is a front view when a piston moves to a compression position (top dead center). It is a disassembled perspective view of the cylinder vicinity. It is a disassembled perspective view which shows a crank mechanism. It is the elements on larger scale which show the front-end | tip part of a piston. It is the side view (a) which shows the front end surface of a piston, and sectional drawing (b) of a front-end | tip part. It is a perspective view which shows a part of opening-and-closing member (switching shaft). It is operation | movement explanatory drawing of a shutter opening / closing mechanism. It is a partial plane sectional view near the air discharge port showing another example of the switching mechanism. It is a perspective view which shows a part of slide member which is another example of an opening / closing member. It is the longitudinal cross-sectional view which looked at the air discharge apparatus of 2nd Example from the front direction. 1 is a cross-sectional view illustrating a configuration of a main part of a fixing device to which an air discharge device according to the present invention is applied. FIG. 3 is an enlarged cross-sectional view illustrating a paper separation unit. It is a perspective view of a paper separation unit. FIG. 5 is a schematic diagram illustrating a configuration in which a paper separation unit is provided in both the fixing roller and the pressure roller to perform air separation. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus including an air discharge device according to the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an appearance of an embodiment of an air discharge device according to the present invention. FIG. 2 is a plan sectional view of the air discharge device. FIG. 3 is a longitudinal sectional view as seen from the side surface direction of the air discharge device, and is seen from the right direction of FIG. Furthermore, FIG. 4 is a longitudinal sectional view from the front direction and shows a state where the piston has moved to the maximum compression position. FIG. 5 is a longitudinal sectional view from the front direction and shows a state when the piston moves to the maximum compression position. FIG. 6 is a front view showing an appearance when the piston is at the maximum compression position. FIG. 1 shows the appearance when the piston is in the maximum expansion position. FIG. 7 is an exploded perspective view of the vicinity of the cylinder. FIG. 8 is an exploded perspective view showing the crank mechanism.

  As shown in these drawings, the air discharge device 500 has front and rear side plates 50 and 51 and a bottom plate 52 constituting the device casing. A cylinder 53 is disposed between the front and rear side plates 50 and 51. Screws are respectively formed on the outer diameter of the tip of the cylinder 53 and the inner diameter of the cylinder head 54, and the cylinder head 54 is screwed to the tip of the cylinder 53. In FIG. 3, the screw fixing portions of both are denoted by reference numeral 200. A piston 55 is disposed in the cylinder 53. The cylinder 53 and the piston 55 are cylindrical in this example. A boss 143 projects from the tip surface of the cylinder head 54. An air discharge port 145 for discharging air inside the cylinder is provided in the boss 143, and a tube (not shown) is fitted at the tip of the air discharge port 145. The piston 55 reciprocates in the cylinder 53 by a mechanism described later, and the air in the cylinder 53 compressed by the movement of the piston 55 is discharged to the outside from the air discharge port 145. Hereinafter, the configuration and operation of the air discharge device 500 will be described in detail.

  A motor 110 is attached on the bottom plate 52. As the motor 110, a pulse motor (stepping motor) is used in this example. A first pulley 112 is fixed to the output shaft 111 of the motor 110. A bracket 80 is erected on the bottom plate 52, and a crank disk 81 is rotatably supported between the bracket 80 and the front side plate 50 via a bearing. A second pulley 90 is fixed to the shaft 81 a (FIG. 3) of the crank disk 81. A timing belt 113 (FIG. 2) is stretched between the first pulley 112 and the second pulley 90, and the rotation of the motor 110 is transmitted to the crank disk 81. In this example, the crank disk 81 and the shaft 81a are integrated, but a structure in which the crank disk is mounted and fixed to the shaft member may be used as a separate member.

  As shown in FIG. 8, a screw hole 81 b is provided at an eccentric position of the crank disk 81, and the crank lever 86 is connected to the crank disk 81 via a bearing 84 and a collar 85 by a screw 83. A rod 72 is fitted to the other end of the crank lever 86 via a bearing 87 and is prevented from coming off via E rings 88 and 88 and spacers 89 and 89. In the rod 72, two grooves 72a for setting the E-ring 88 are formed. The rod 72 is a member connected to the piston 55 (see FIG. 2). In this manner, the piston 55 is mounted via the rod 72 at the tip of the crank lever 86 that is rotatably attached to the crank disk 81. Therefore, in FIG. 4, when the crank disk 81 rotates around the shaft 81 a, the crank lever 86 attached eccentrically from the shaft performs a crank motion, whereby the piston 55 reciprocates in the cylinder 53.

  When the crank disk 81 rotates once, the crank lever 86 also rotates once, and the piston 55 reciprocates once. In this example, the bottom dead center at which the cylinder volume is maximum is set to the home position (HP) position, and FIG. 4 shows a state where the piston 55 is located at the home position. Further, the compression position where the cylinder volume is minimized is the top dead center, and FIG. 5 (and FIG. 2) shows a state where the piston 55 is located at the top dead center.

  A filler 82 is projected on the peripheral surface of the crank disk 81, and a sensor 95 for detecting the filler 82 is disposed on the bottom plate 52. The sensor 95 has a light emitting part and a light receiving part, and is detected when the filler 82 blocks the light of the sensor 95. In this example, when the piston 55 is located at the home position (FIG. 4), the tip of the filler 82 in the rotational direction is set to be the sensor position.

  When the drive signal is input to the motor 110 from the state shown in FIG. 4 in which the piston 55 is stopped at the home position, the motor 110 rotates counterclockwise in the drawing, and the crank disk 81 is connected via the timing belt 213. Rotate in the direction. The rotation of the crank disk 81 is transmitted to the crank lever 86, and when the crank disk 81 rotates 1/2, the piston 55 ends the compression and air discharge process and moves to the top dead center. The state where the piston is located at the top dead center is shown in FIGS.

  Further, when the crank disk 81 rotates, the piston 55 shifts to a return process. When the filler 82 of the crank disk 81 blocks the sensor light, the output of the sensor 95 changes, and the motor 110 is stopped by detecting this change. In this way, one step of the air pump is performed. By repeating one step of the air pump continuously, air is intermittently discharged. For example, the piston 55 can be driven at a high speed of about 120 reciprocations per minute and used for air separation of paper in the image forming apparatus.

  Since the piston 55 is connected to the crank disk 81 via the crank lever 86, the piston position can be detected when the sensor 95 detects the filler 82. That is, in this example, the sensor 95 detects the filler 82 when the piston 55 returns to the home position (bottom dead center).

FIG. 9 is a partially enlarged view showing the tip portion of the piston 55. FIG. 10 is a side view (a) showing the front end surface of the piston 55 and a cross-sectional view (b) of the front end portion.
As can be seen from FIG. 2, the piston 55 is attached to the tip of the crank lever 86 (the left end in FIG. 2) via a rod 72. Further, as shown in FIG. 9, an O-ring 56 is fitted in the groove portion 57 provided in the vicinity of the tip portion of the piston 55. The front end surface of the piston 55 is provided with an intake port 58 that communicates the inside and outside of the piston. In this example, a leaf valve 60 having a substantially triangular shape is fixed to the piston front end face via a presser plate 61 so that the intake port 58 can be closed. Reference numeral 59 denotes a screw hole provided in the piston front end surface, and reference numeral 62 denotes a fixing screw. In the initial state, the leaf valve 60 is in close contact with the piston tip surface without any gap, and closes the intake port 58. The leaf valve 60 is made of, for example, a polyester film or stainless steel, has a thickness of 0.05 to 0.2 mm, has flexibility, and easily returns to its original state even when pressed. be able to.

  When the piston 55 moves in the compression direction (leftward in FIG. 4), the leaf valve 60 is in close contact with the piston front end surface to close the intake port 58 and prevent air leakage (into the piston). When the piston 55 moves in the return stroke (rightward in FIGS. 2 and 5), the leaf valve 60 is expanded and air is sucked into the cylinder (from inside the piston). In this way, air is sucked in conjunction with the operation of the piston. In this embodiment, the air intake valve is provided on the piston side, but the air intake valve may be provided on the cylinder side (for example, the end face of the cylinder head 54).

  By the way, when the piston moves in the compression direction, if the air is discharged as it is without accumulating air in the cylinder, the discharge pressure cannot be increased, and the air can be discharged vigorously. Can not. Therefore, in the air discharge device of this example, an open / close member (shutter member) is provided at the air discharge port (discharge opening) 141 of the cylinder 53, and the open / close member is opened at a predetermined timing (the open / close member until the predetermined timing is reached). Is configured so that air can be discharged vigorously by increasing the discharge pressure.

  As shown in FIG. 7, the boss 143 provided with the air discharge port 145 is provided with a through-hole (circular cross section in this example) 144 crossing the air discharge port 145 (in this example, orthogonal). It has been. A switching shaft 135 (opening / closing member) having a cylindrical cross section is inserted into the through hole 144. The switching shaft 135 is inserted into a bearing (not shown) fitted into a projection 137 projecting from the cylinder head 54 and a through hole 144 and is rotatably supported. As shown in FIG. 11, an E-ring is attached to one end (back end portion) of the switching shaft 135 and a disk member 134 is fixed to the other end (front end portion). Retaining and axial positioning are made. A flat plate cutting portion 136 is provided at a position corresponding to the air discharge port 145 of the switching shaft 135. The flat plate cutting portion 136 is formed by cutting out a part of the circumferential surface of the cylindrical switching shaft 135 and is provided in a flat plate shape. In this example, the flat plate portion has a flat surface (diameter flat plate) passing through the axis. As shown, both sides of the flat plate portion are cut out in the same shape. In a state where the flat plate cut portion 136 is oriented in the vertical direction as shown in FIG. 4, the flat plate cut portion 136 blocks the air discharge port 145, and the air in the cylinder 53 cannot exit from the air discharge port 145. Then, as shown in FIG. 5, when the flat plate cut portion 136 faces the horizontal direction, the air discharge port 145 is opened, and the air in the cylinder 53 can exit from the air discharge port 145 through both sides of the flat plate portion.

  In this example, by rotating the switching shaft 135 by 90 degrees, the orientation of the flat plate cutting portion 136 is switched between the vertical direction and the horizontal direction, and the air discharge port 145 is switched between closing and opening. Further, the shutter opening / closing mechanism described below is used to switch between closing and opening of the air discharge port 145 (that is, rotating the switching shaft 135 by 90 degrees) at a predetermined timing, so that the air is discharged until the predetermined timing is reached. The discharge port 145 is closed, and the pressure inside the cylinder is increased so that air can be discharged vigorously.

  As shown in FIGS. 2 and 8, a cam plate 131 is fixed to the front end of the shaft 81 a of the crank disk 81 with screws so as to be located outside the front side plate 50. The cam plate 131 has a sector shape as shown in FIG. 12, and includes an outer peripheral arc portion 131a, a first straight portion 131b, an inner peripheral arc portion 131c, and a second straight portion 131d. It is preferable to form the connecting portion of each portion in an R shape (in a curved shape) because the movement of a cam follower (roller 142) described later can be made smooth. The second straight portion 131d is provided so as to be tangent to the inner circumferential arc portion 131c. FIG. 12 will be described later.

  Further, as shown in FIG. 2, a shaft 140 is protruded and fixed on the outer surface of the front side plate 50. A link lever 141 is rotatably supported on the shaft 140. As shown in FIG. 1, the link lever 141 is a long and thin plate-like member, and a roller 142 serving as a cam follower is pivotally supported at one end portion. The other end of the link lever 141 is engaged with the end surface of the disk member 134 via an engagement pin 139 configured as a stepped screw.

  A tension spring 157 is installed between the link lever 141 and the front side plate 50 to urge the link lever 141 so as to press the roller 142 against the peripheral surface of the cam plate 131. Accordingly, the roller 142 is moved according to the rotation of the cam plate 131, and the link lever 141 is swung. Then, the disk member 134 is rotated via the engagement pin 139 by the swinging of the link lever 141.

FIG. 12 is an explanatory diagram of the operation of the shutter opening / closing mechanism.
FIG. 12A shows a state of the shutter opening / closing mechanism when the piston 55 of the air discharge device is located at the home position. At this time, the flat plate cutting portion 136 provided on the switching shaft 135 is directed in the vertical direction to close the air discharge port 145 described above (state of FIG. 4). From this state, when the crank disk 81 rotates counterclockwise in FIG. 4, the piston 55 moves in the compression direction, so the cam plate 131 also rotates counterclockwise from the state of FIG. In the range where the outer circumferential arc 131a slides on the roller 142 (up to the position shown in FIG. 12B), the position of the roller 142 that is the cam follower does not change, so the link lever 141 does not move and the disk member 134 is moved. Since the air does not rotate, the air discharge port 145 remains closed. Therefore, the pressure in the cylinder 53 increases as the piston 55 moves.

  Then, when the cam plate 131 further rotates from the position shown in FIG. 12B and the roller 142 is disengaged from the outer circumferential arc portion 131a (slidably contacts the first linear portion 131b), the link lever 141 is turned by the biasing force of the spring 157. Rotate around. When the roller 142 reaches the inner circumferential arc portion 131c, the link lever 141 becomes substantially horizontal as shown in FIG. By the rotation of the link lever 141, the disk member 134 rotates counterclockwise in the figure, and the switching shaft 135 (and its flat plate cutting portion 136) on which the disk member 134 is mounted and fixed also rotates. As shown in (c), the flat plate cut portion 136 is horizontal and the air discharge port 145 is opened. The rotation angle of the cam plate 131 until the roller 142 is removed from the outer circumferential arc portion 131a and reaches the inner circumferential arc portion 131c via the straight line portion 131b is small when the movement distance of the piston 55 is set. In the meantime, the air discharge port 145 changes from the closed state to the open state. For this reason, the pressure of the air that has been increased in the cylinder is released at once, and the air is discharged from the air discharge port 145 with great force.

  FIG. 12D shows the state when the piston 55 reaches the maximum compression position (top dead center). In a range where the roller 142 slides on the inner circumferential arc portion 131c, the link lever 141 does not rotate and the air discharge port 145 is maintained in an open state. When the crank disk 81 and the cam plate 131 further rotate from the state of FIG. 12D and the roller 142 slides on the second linear portion 131d, the roller 142 is gradually pushed up, and the link lever 141 is rotated counterclockwise in the drawing. By rotating, the other end of the link lever 141 is pushed down, the disk member 134 rotates clockwise in the figure, and the air discharge port 145 is gradually closed. As described above, the second straight portion 131d is provided so as to be tangent to the inner circumferential arc portion 131c. Therefore, when the roller 142 moves from the inner circumferential arc portion 131c to the second linear portion 131d, the second linear portion 131d smoothly collides. 142 is pushed up.

  And when the roller 142 transfers to the outer periphery circular arc part 131a, the air discharge port 145 is completely closed. FIG. 12E shows a start state of air suction in the piston return process. From the state of FIG. 12E, the crank disk 81 and the cam plate 131 further rotate counterclockwise in the figure, and when the piston 55 returns to the home position, the state of FIG. After the air discharge port 145 is closed, the closed state of the air discharge port 145 is maintained in a range where the roller 142 slides on the outer circumferential arc portion 131a.

  Thus, in the air discharge device of the present invention, the open / close member mechanically connected to the piston is provided in the air discharge port, and the open / close member (that is, the air discharge port) is closed until a predetermined timing in the compression process. Since the air discharge port can be opened in a short time near the top dead center, the air pressure can be increased in the cylinder, and the air with the increased pressure can be discharged all at once. Thereby, an air tank and a solenoid valve become unnecessary.

  In this embodiment, a pulse motor is used as a driving source of the air pump. However, since the motor 110 rotates in one direction and does not reverse the motor, a switching load (reverse load) is used when switching the rotation direction. ) Does not occur, motor vibration, noise, increase in starting torque, and the like can be prevented, and a long life air discharge device can be realized by preventing a decrease in motor life.

  Furthermore, since driving and stopping can be repeated without using a single-rotation clutch, there is no problem that the clutch will reach the end of its life due to a large load when the clutch is engaged. Can do.

In addition, since there is no air compression at the initial stage of rotation of the motor (the compression load is almost negligible in the initial stage), the load is light and an excessive load is not applied to the motor shaft. Further, by using a pulse motor, the rotation speed can be freely set according to the air discharge cycle.
By the way, as described above, the air discharge device of this example uses a stepping motor as a drive source, but at the initial stage of rotation (initial movement from the home position), the motor is slowly started up to keep the drive torque low and compressed. By increasing the rotational speed at a predetermined stage of the stroke, it is possible to perform low torque driving at the same cycle as usual (when the rotational speed is constant).

  Further, in the air discharge device 500 of this example, a low friction material is used as the material of the cylinder 53 and the piston 55. Since the fluororesin is expensive, a resin obtained by adding fluorine powder to a low friction material such as polyacetal resin may be used. Thereby, slipperiness and abrasion resistance can be improved and a long life can be achieved.

  13 and 14 show another example of an opening / closing member that opens and closes the air discharge port 145. In this configuration example, a switching member 170 (opening / closing member) is used instead of the switching shaft 135. The switching member 170 of this example is provided as a cylindrical shaft member similar to the switching shaft 135. However, in this configuration example in which the switching member 170 is slid in the longitudinal direction, the switching member 170 is not necessarily provided as a cylindrical member. A prismatic member (a member having a polygonal cross-sectional shape) may be used. The switching member 170 has a small volume portion (small diameter portion in this example) 171 as a configuration corresponding to the flat plate cut portion 136 of the switching shaft 135. Then, as shown in FIGS. 13A and 13B, the switching member 170 is slid in the axial direction to switch between closing and opening the air discharge port 145. As a configuration for sliding the switching member 170, an end face cam (bell cam) 161 which is a kind of a three-dimensional cam is used. The end face cam 161 is a disk-like member that is rotatably supported by the shaft 160. The end face cam 161 has a thin plate portion 161a having a small thickness and a thick plate portion 161b having a large thickness, and both are connected by a smooth curved surface. . The end cam 161 is rotated at a predetermined timing by the mechanism described with reference to FIG. A disk member 174 is fixed to the switching member 170, and a compression spring 173 is fitted to the switching member 170 between the disk member 174 and the boss 172 on the main body side.

  As shown in FIG. 13A, when the tip of the switching member 170 is in contact with the thin plate portion 161 a of the end face cam 161, the switching member 170 is pushed downward in the drawing by the urging force of the spring 173, and the small diameter portion 171. Is disconnected from the air discharge port 145, so that the air discharge port 145 is closed. When the end face cam 161 rotates and the thick plate portion 161b moves to the switching member 170 portion, as shown in FIG. 19B, the spring 173 is compressed and the switching member 170 is moved upward (apparatus). The small diameter portion 171 becomes the position of the air discharge port 145 and the air discharge port 145 is opened. When the end face cam 161 rotates and the thin plate portion 161a moves again to the switching member 170 portion, the air discharge port 145 is closed.

Next, a second embodiment of the air discharge device will be described.
In the air discharge device of the first embodiment described above, the crank disk 81 is rotated from the motor 110 via the timing belt 113. However, in the second embodiment, the gear train is moved from the motor as the driving means. In this configuration, the crank disk 81 is rotated. In addition, since the principal part structure of an air pump is the same as 1st Example, it demonstrates centering on a different part.

  FIG. 15 is a longitudinal sectional view of the air discharge device of the second embodiment as viewed from the front. As shown in this figure, a cylinder 53 is supported between the front and rear side plates 50 and 51, and a piston 55 is disposed in the cylinder 53 and reciprocates in the left-right direction in FIG. It is the same as the discharge device. Also, a boss 143 projects from the tip surface of the cylinder 53, an air discharge port 145 is provided in the boss 143, and the air in the cylinder 53 compressed by the movement of the piston 55 is discharged from the air discharge port 145 to the outside. The same is true.

  In FIG. 15, the motor 110 is attached to a motor bracket 205 protruding from the bottom plate 52. The motor 110 is a pulse motor. A worm 212 is press-fitted to the output shaft 211 of the motor 110. The tip 212a of the worm 212 is supported by a holder 209 provided so as to face the motor bracket 205 via a bearing. The worm 212 is supported by the holder 209 on the tip of the worm because a downward bending force is applied by the reaction from the worm wheel 213 during rotation. The worm wheel 213 supported between the front and rear plates 50 and 51 by the shaft 202 is engaged with the worm 212 and is rotated by the worm 212 when the motor 110 is driven.

  In addition, as a normal worm wheel, a gear having a shape in which a central portion is recessed relative to the worm is used, but a helical gear is used in this embodiment. Further, by using a worm gear (worm and worm wheel), the reduction ratio is increased to increase the torque.

  In the second embodiment, a gear 215 is mounted and fixed on the shaft 81 a of the crank disk 81, and the gear 215 is engaged with the worm wheel 213. In this example, since a helical gear is used for the worm wheel 213, the gear 215 also uses a helical gear. The output of the motor 110 is transmitted to the crank disk 81 through the gear train as described above, and the piston 55 is reciprocated. It is also possible to use a flat leaf gear instead of a helical gear. It is also possible to change the direction of the motor (the direction of the motor output shaft is the same as that of the shaft 81a of the crank disk 81) and to transmit the driving force with a general flat leaf gear or helical gear without using the worm gear. It is.

  Since the configuration and operation of the crank mechanism for reciprocating the piston 55 are the same as those in the first embodiment, description thereof is omitted. Further, the configuration and operation of the shutter opening / closing mechanism by the link lever 141 are the same as those in the first embodiment, and the description thereof is omitted. Further, the switching shaft 135 or the switching member 170 described above can be used as the opening / closing member, and when the switching member 170 is used, the configuration described with reference to FIGS.

Next, an embodiment in which the air ejection device according to the present invention is applied to paper separation (air separation) in a fixing device of an image forming apparatus will be described with reference to FIGS.
The unit of the fixing device 15 shown in FIG. 16 is configured by a belt fixing method. The aim of the belt fixing system is to reduce the heat capacity of the surface and quickly raise the temperature after the switch is turned on. Furthermore, the aim of the belt fixing system is to make the surface hardness of the fixing roller softer than the surface hardness of the pressure roller (thicken the rubber layer) so that the paper that exits the nip with the pressure roller faces downward, It is to improve the separation from the fixing roller / fixing belt. As in this example, if the separation performance of the paper separation unit is sufficient, the surface hardness of the fixing roller and the pressure roller may be made equal to discharge the paper in the tangential direction of both roller nip portions.

  The surface of the fixing belt 3 is heated by three heaters 5 built in the heating roller 2, and the heated fixing belt 3 heats an unfixed image at a fixing nip portion between the fixing roller 1 and the pressure roller 10. Pressurize to fix the image.

  Here, the fixing belt 3 has a polyimide film base material covered with a surface layer of silicone rubber. The fixing roller 1 is formed by forming a rubber layer 6 on a roller cored bar 4. The fixing belt 3 wound around the fixing roller 1 and the heating roller 2 is stretched to a predetermined extent by a belt tension 14. The pressure roller 10 forms a rubber layer 13 on a core metal 11 and has a heater 12 built therein. The purpose of the heater 12 is to prevent the temperature of the fixing nip portion from being lowered by heating from the pressure roller 10. The rubber layers 6 and 13 are made of silicone rubber and have the aim of improving heat resistance and image coloring. The thickness of each rubber is changed, that is, the rubber thickness on the fixing roller side is increased, and the rubber thickness is set to bite into the fixing roller side.

  In this method, the surfaces of both the fixing belt 3 and the pressure roller 10 are made of silicone rubber and are sticky. Therefore, a slight amount of silicone oil is applied to the surface of the belt so that the paper P is easily peeled off. On the upstream side of the fixing nip portion, a fixing inlet guide plate 7 is arranged to guide the paper P to the fixing nip portion. The paper P exiting the fixing nip portion passes between the paper discharge lower guide 9 while being guided by the lower surface of the paper separation unit 20, and then passes between the paper discharge upper guide 8 and the paper discharge lower guide 9. Are ejected.

  FIG. 17 is an enlarged cross-sectional view of the paper separation unit 20, and FIG. 18 is a perspective view of the paper separation unit 20. The nozzle main body 21 of the paper separation unit 20 has a duct 22 extending in the longitudinal direction therein. The pipe line 22 is branched at three places near the center and both ends in the longitudinal direction of the sheet separating unit 20, and branch lines 23, 24, and 25 are provided toward the tip of the nozzle. The distal ends of the branch pipes 23, 24, 25 are provided as small-diameter portions and form nozzles 26, 27, 28 that serve as air outlets. As can be seen from FIG. 16, the tip of the nozzle body 21 has an acute cross-sectional shape with a sharp tip, and the air outlets 29 provided at the tip of each nozzle 26, 27, 28 The bottom surface portion 21a provided at the tip of the nozzle body 21 and the wall surface portions 21b and 21b on both sides of the nozzle are surrounded and guided so that the discharged air is prevented from diffusing and efficiently directed to the fixing nip. ing. One end of the conduit 22 is opened at the end face of the nozzle body 21, and an air tube 242 is fitted into the conduit 22. The air tube 242 is connected to the air discharge port 145 (the boss 143 provided with the air discharge port 145) of the air discharge device described above, and the air supplied from the air discharge device is jetted from the nozzles 26, 27, 28 to fix the fixing nip. The paper coming out from the section is separated (air separation). In this example, as described above, the air blowing port 29 from each nozzle is surrounded and guided so that the air blown from each nozzle goes straight to the nip portion and exhibits a strong collision force. Thus, the paper can be reliably separated.

  Incidentally, the paper may be wound not only on the fixing roller side but also on the pressure roller side. For this reason, a paper separation unit 20 may be provided on the pressure roller 10 side to perform air separation. FIG. 19 shows a configuration in which the paper separation unit 20 is provided on both the fixing roller and the pressure roller to perform air separation. The configuration in which the paper separation unit 20 is provided on both the fixing roller and the pressure roller to perform air separation is particularly effective for preventing paper wrapping during double-sided printing. During double-sided printing, the surface that has been fixed first becomes the pressure roller side during the next (back side) fixing, and therefore the wrapping around the pressure roller side tends to occur. By providing the air separation, it is possible to effectively prevent paper wrapping during double-sided printing.

  Further, in the configuration of FIG. 16, in order to prevent wrapping around the fixing roller 1 side, the pressure roller 10 is made to bite into the fixing roller 1 and the separation property is improved on the fixing roller 1 side. In the configuration in which the paper separation unit 20 is provided in both the roller and the pressure roller to perform air separation, the fixing roller and the pressure roller can be uniformly deformed to discharge the paper in the tangential direction, and the fixing nip It is possible to prevent the occurrence of wrinkles and the like by maintaining the pressure balance. If air is supplied to the sheet separation unit 20 provided on both the fixing roller and the pressure roller using the above-described air discharge device according to the present invention, the air discharge device is small, so there is a space limitation. Even in a large image forming apparatus, air separation can be performed by both the fixing roller and the pressure roller, so that more reliable separation can be realized and jamming due to paper winding can be prevented in advance. If the capacity of the air ejection device is appropriately set, air can be supplied to the sheet separation unit 20 of both the fixing roller and the pressure roller with one air ejection device.

Finally, an example of an image forming apparatus including the fixing device 15 will be described.
The image forming apparatus shown in FIG. 20 is configured as a copying machine. A copying machine main body 100 is disposed at the center, and a sheet feeding unit 200 configured in a table shape is disposed below the copying machine main body 100. A scanner 300 and a scanner 300 are disposed above the copying machine main body 100. An automatic document feeder (ADF) 400 is disposed above the.

  The copying machine main body 100 is provided with an intermediate transfer belt 16 as an image carrier constituted by a flexible endless belt wound around a plurality of support rollers. The intermediate transfer belt 16 is rotationally driven by a driving device (not shown), whereby the intermediate transfer belt 16 is driven to run in the clockwise direction indicated by the arrow. Black, cyan, magenta, and yellow image forming units 18 are arranged side by side on the upper traveling side of the intermediate transfer belt 16 that travels in this manner. That is, the tandem image forming unit is configured by arranging the four image forming units 18 side by side.

  The four image forming units 18 include a photosensitive drum 40 as a latent image carrier in contact with the intermediate transfer belt 16. Around the photosensitive drum 40, a charging device, a developing device, a cleaning device, a static eliminator, and the like are arranged. Further, a primary transfer is provided inside the intermediate transfer belt 16 at a position where the photosensitive drum 40 is in contact with the intermediate transfer belt 16. A device 19 is provided. In the present embodiment, the four image forming units 18 have the same structure, but the color of the toner of the developing device is different to four colors of black, cyan, magenta, and yellow. In the drawing, only the rightmost image forming unit 18 is shown with reference numerals of the developing device 60 and the cleaning device 70.

  Above each image forming unit 18, an exposure device 21 that irradiates the surface of each photosensitive drum with light-modulated laser light is disposed, and this laser light is irradiated to the photosensitive drum between the charging device and the developing device. .

  A secondary transfer device 39 is provided on the side opposite to the image forming units 18 with the intermediate transfer belt 16 in between. In the illustrated example, the secondary transfer device 39 is arranged such that a secondary transfer belt, which is an endless belt, is wound between two rollers, and the belt is pressed against the transfer counter roller via the intermediate transfer belt 16. ing.

  The fixing device 15 described above is provided on the left side in the drawing of the secondary transfer device 39. The secondary transfer device 39 also has a sheet conveying function for conveying the image-transferred sheet to the fixing device 15. Below the secondary transfer device 39 and the fixing device 15, a sheet reversing device 38 that reverses the sheet to record images on both sides of the sheet is disposed. Now, a case where copying is performed using the color copying machine configured as described above will be described. First, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a 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. At that time, the scanner 300 is immediately driven to travel the first traveling body 33 and the second traveling body 34. 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.

  Further, when a start switch (not shown) is pressed, the intermediate transfer belt 16 is rotated, and at the same time, the respective photoreceptors 40 are rotated by the individual image forming units 18 so that the black, yellow, A magenta / cyan monochrome image is formed. As the intermediate transfer belt 16 travels, the single color images are sequentially transferred to form a composite color image on the intermediate transfer belt 16.

  Further, by pressing the start switch, one of the paper feed rollers 42 of the paper feed unit 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped.

  Or, when manual feed is selected, the sheet is fed out from the manual feed tray 41, separated into one sheet, put into the manual feed path, and abutted against the registration roller 49 and stopped.

Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 16, the sheet is fed between the intermediate transfer belt 16 and the secondary transfer device 39, and transferred by the secondary transfer device 39. Full color images are recorded on the sheet at once.
The sheet after the image transfer is conveyed by the secondary transfer device 39 and sent to the fixing device 15, and heat and pressure are applied by the fixing device 15 to fix the transferred image. Then, the sheet is discharged by a discharge roller and discharged by a discharge tray. Stack on top of 37. Alternatively, the conveyance direction is switched by the switching claw and is put into the sheet reversing device 38, where it is reversed and guided again to the transfer position, the image is recorded on the back side, and then discharged onto the discharge tray 37 by the discharge roller.

  On the other hand, the intermediate transfer belt 16 after image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 16 after image transfer, and is prepared for re-image formation by the tandem image forming unit.

  The fixing device 15 includes the paper separation unit 20 as described above, and air supplied from the air discharge device 500 and discharged from the nozzles 26, 27, and 28 of the paper separation unit 20 to the fixing nip. The paper ejected from the fixing nip portion is reliably separated (air separation). Since the air discharge device according to the present invention is reduced in size, it can be mounted on the image forming apparatus as a supply source of separation air of the fixing device. A conventional air supply system including a compressor and an air tank has to be large, and can only be used for a commercial printing machine. However, even in an image forming apparatus disposed in an office or the like, an air separation system is used. Secure paper separation is possible. As the air discharge device 500, either the first embodiment or the second embodiment described above can be used.

  In addition, since the air discharge device according to the present invention uses a small motor as a driving source in one direction rotation, there is no switching load (reverse direction load) accompanying rotation direction switching, and motor vibration, noise, and starting torque increase. It is possible to prevent a decrease in motor life and to realize a long-life air discharge device. Further, since no clutch is required, the life of the air discharge device is not reduced due to the clutch life.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. For example, it is possible to adopt appropriate shapes for the cylinder and the air pump. Moreover, the capability as an air pump, the discharge timing of air, etc. can be set suitably.

  When an air discharge device is used in the image forming apparatus, not only paper separation (peeling) in the fixing device, but also air separation or an air transportation method can be employed for paper separation and paper transportation in the paper feeding unit. Further, the configuration of each part of the fixing device and the image forming apparatus is arbitrary. The present invention can be applied not only to a color image forming apparatus but also to a monochrome apparatus. Of course, the image forming apparatus is not limited to a copying machine, but may be a printer, a facsimile machine, or a multifunction machine having a plurality of functions.

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Heating roller 3 Fixing belt 10 Pressure roller 15 Fixing device 20 Paper separation unit 21 Nozzle body 26, 27, 28 Nozzle (air blowing port)
53 Cylinder 54 Cylinder head 55 Piston 81 Crank disc 82 Filler 86 Crank lever 90 Second pulley 95 Sensor 110 Stepping motor 112 First pulley 113 Timing belt 131 Cam plate 135 Switching shaft (opening / closing member)
136 Flat cut part 141 Link lever 142 Roller (cam follower)
145 Air discharge port 170 Switching member (opening / closing member)
500 Air discharge device

JP 2005-157179 A JP 2008-003277 A

Claims (5)

An air pump having a cylinder and a piston that reciprocates in the cylinder is provided, and the piston is reciprocated through a crank mechanism from a motor that is a driving source to drive the air pump to discharge pressurized air at a predetermined timing. In the air discharge device,
Providing a detecting means for detecting the position of the piston;
The motor is rotating in one direction;
The rotation and stop of the motor are controlled based on the detection signal of the detection means, and the air pump performs the steps of air compression, air discharge, and air suction between one rotation of the crank mechanism and one reciprocation of the piston. With
An opening / closing member provided at an air outlet of the air pump to open or close the air outlet;
It is mechanically connected to both the piston and the opening and closing member, and when the piston is compressed and moved, the opening and closing member is kept closed until reaching a predetermined point and when the piston reaches a predetermined point, A switching mechanism for switching the open / close member to an open state;
Air discharging apparatus according to claim <br/> be provided with a. The crank mechanism has a crank disk rotatably supported, and a crank lever having one end eccentrically pivoted to the crank disk,
2. The air discharge device according to claim 1, wherein the detection unit detects a position of the piston by detecting a member to be detected provided on the crank disk. 3.   The air discharge device according to claim 1, wherein the motor is a stepping motor.   The air discharge device according to claim 1, wherein the detection unit is an optical sensor. A heating rotating member that heats the recording paper; and a pressure rotating member that contacts the surface of the heating rotating member to form a nip portion, and further includes a separating unit that separates the recording paper from the heating rotating member by air. An image forming apparatus including a fixing device,
An air discharging apparatus according to any one of claims 1 to 4, the image forming apparatus characterized by supplying air to said separating means from the air discharging apparatus.

Images