JP4658984B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copying machine, and a facsimile, for example, a printer, an image forming unit is disposed, and a photosensitive drum, a charging roller, a developing device, and the like are disposed in the image forming unit. Then, the surface of the photosensitive drum uniformly and uniformly charged by the charging roller is exposed by an LED head to form an electrostatic latent image, and the electrostatic latent image is developed by a developing device to form a toner. An image is formed, the toner image is transferred onto a sheet of paper as a medium by a transfer roller, and fixed by a fixing device, whereby an image is formed and printing is performed.

  For this purpose, the printer has a paper feed mechanism that feeds the paper from the paper feed cassette to the transport path, a transport mechanism that transports the fed paper, an image forming mechanism that forms a toner image, and transfers the paper to the paper. A fixing mechanism for fixing the toner image, a discharge mechanism for discharging the paper, and the like are provided, and each mechanism performs processing for each mechanism while the paper is being transported at a predetermined transport speed. It has become.

Then, when the paper is transported from the upstream mechanism to the downstream mechanism in the paper transport direction, the downstream side mechanism is formed so that a slack of the paper is formed between the upstream mechanism and the downstream mechanism. The transport speed by the mechanism is set lower than the transport speed by the upstream mechanism (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2000-19005

  However, in the conventional printer, for example, if the left and right slacks in the width direction of the paper are different between the image forming mechanism and the fixing mechanism, it is large when the paper is separated from the image forming mechanism on the large slack side. As a result, the surface of the sheet on which the toner image is transferred, that is, the image forming surface and the image forming mechanism are rubbed, and the image quality is deteriorated.

  The present invention provides an image forming apparatus that solves the problems of the conventional printer, prevents the medium from jumping greatly between the upstream mechanism and the downstream mechanism, and improves the image quality. The purpose is to provide.

  Therefore, in the image forming apparatus of the present invention, the upstream side mechanism that transports the medium on which the developer image is formed at a predetermined transport speed and performs predetermined processing, and the medium on which the developer image is formed. The medium is transported at a transport speed lower than the transport speed to form a slack in the medium, and is disposed between a downstream mechanism that performs a predetermined process, and the upstream mechanism and the downstream mechanism. And a slack correction device that detects and corrects different slacks in the width direction.

  According to the present invention, in the image forming apparatus, the upstream side mechanism that transports the medium on which the developer image is formed at a predetermined transport speed and performs a predetermined process, and the medium on which the developer image is formed. The medium is transported at a transport speed lower than the transport speed to form a slack in the medium, and is disposed between a downstream mechanism that performs a predetermined process, and the upstream mechanism and the downstream mechanism. And a slack correction device that detects and corrects different slacks in the width direction.

  In this case, a slack correction device is disposed between the upstream mechanism and the downstream mechanism, and detects and corrects slack that is different in the width direction of the medium. Therefore, the upstream mechanism and the downstream mechanism It is possible to prevent the medium from jumping up and down and improve the image quality.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a schematic view of the printer according to the first embodiment of the present invention.

  As shown in the drawing, a paper feed cassette 11 serving as a medium accommodating portion for accommodating paper P as a medium is disposed in the lower part of the printer main body, that is, the apparatus main body, and is adjacent to the front end of the paper feed cassette 11. Thus, a paper feed mechanism m1 that separates and feeds the paper P one by one is provided. The sheet feeding mechanism m1 includes sheet feeding rollers 12a and 12b and a sheet feeding motor (not shown) as a sheet feeding driving unit that rotates the sheet feeding rollers 12a and 12b, and the sheet fed by the sheet feeding mechanism m1. P is sent to a transport mechanism m2 disposed on the downstream side in the transport direction of the paper P. The transport mechanism m <b> 2 includes transport roller units 14 and 15, and the skew of the paper P is forced in the transport roller unit 15. The transport roller portions 14 and 15 are each disposed as a first roller disposed on the back side of the paper P, a resist roller as opposed to the resist roller, and pressed against the resist roller. A pressure roller is provided as a second roller that rotates around.

  Thereafter, the paper P is sent to the image forming mechanism m3, and the image forming mechanism m3 performs image formation for each color of black, yellow, magenta, and cyan. The image forming mechanism m3 includes image forming units 22Bk, 22Y, 22M, and 22C, LED heads 21Bk, 21Y, 21M, and 21C as exposure apparatuses, and a transfer unit u1 as a transfer unit. Then, the transfer belt 17 is moved as the paper P is driven by a belt motor (not shown) as a belt transporting drive unit and a transfer belt 17 as a first transfer member. And is passed between the image forming units 22Bk, 22Y, 22M, and 22C and the transfer unit u1.

  Each of the image forming units 22Bk, 22Y, 22M, and 22C has a photosensitive drum 52Bk, 52Y, 52M, and 52C as an image carrier, and a uniform surface on each of the photosensitive drums 52Bk, 52Y, 52M, and 52C. A toner as a developer on the electrostatic latent image formed on the photosensitive drums 52Bk, 52Y, 52M, and 52C by the charging roller (not shown) as a charging device for uniformly charging, the LED heads 21Bk, 21Y, 21M, and 21C As a cleaning device that removes the toner remaining on the surfaces of the photosensitive drums 52Bk, 52Y, 52M, and 52C after transfer Provided with a cleaning blade (not shown). The developing device includes a developing roller as a developer carrying member for attaching toner to the electrostatic latent image, a toner supply roller as a developer supplying member for supplying toner to the developing roller, and the like. Each of the photosensitive drums 52Bk, 52Y, 52M, and 52C is rotated by a drum motor (not shown) serving as an image forming drive unit.

  Each of the image forming units 22Bk, 22Y, 22M, and 22C is detachably disposed on the apparatus main body. For this purpose, an upper cover 23 is disposed on the upper part of the apparatus main body so as to be freely opened and closed. The LED heads 21Bk, 21Y, 21M, and 21C are held by the upper cover 23.

  The transfer unit u1 includes a drive roller 27 as a first roller, an idle roller 28 as a second roller, the transfer belt 17 stretched between the drive roller 27 and the idle roller 28, The transfer rollers 51Bk, 51Y, 51M, 51C as the second transfer members disposed opposite to the respective photosensitive drums 52Bk, 52Y, 52M, 52C with the transfer belt 17 interposed therebetween, and the driving roller 27 are rotated. For example, a belt motor (not shown) serving as a driving unit for conveyance is provided. The idle roller 28 applies tension so that the transfer belt 17 does not sag.

  The transfer rollers 51Bk, 51Y, 51M, and 51C respectively transfer the toner images of the respective colors formed by the photosensitive drums 52Bk, 52Y, 52M, and 52C on the paper P in the image forming units 22Bk, 22Y, 22M, and 22C. Transfer to form a color toner image.

  Subsequently, the paper P is sent to the fixing mechanism m4. The fixing mechanism m4 includes a fixing device 18 as a fixing device, and a color toner image is fixed on the paper P in the fixing device 18 to form a color image. In this embodiment, a slack correction device u2 for preventing the paper P from jumping up is disposed between the image forming mechanism m3 and the fixing mechanism m4.

  The fixing device 18 includes a fixing roller 25 as a first roller that is rotated by a fixing motor (not shown) as a driving unit for fixing and a fixing roller 25 as a fixing member, and a second roller that rotates with the fixing roller 25. A pressure roller 26 as a roller and a pressure member is provided, and the toner is melted on the paper P by heat from a heater 25 a as a heating body provided in the fixing roller 25.

  The fixing roller 25 is formed by coating an elastic body such as silicone rubber on a core metal such as iron or aluminum, and the surface of the elastic body is coated with a fluorine-based resin. Prevent adhesion. The pressure roller 26 is formed by coating an elastic body such as silicone rubber on a core metal such as iron or aluminum, and the surface of the elastic body is coated with a fluorine resin, and the fluorine resin This prevents the toner of the unfixed toner image from being offset and adhering to the fixing roller 25 when a paper jam occurs during conveyance of the paper P.

  Next, the paper P discharged from the fixing device 18 is sent to the discharge mechanism m5. The discharge mechanism m5 includes a transport roller unit 19 and a discharge transport roller unit 20, and after the paper P is transported by the transport roller unit 19, it is discharged to the upper cover 23 outside the apparatus main body by the discharge transport roller unit 20. .

  The transport roller unit 19 and the discharge transport roller unit 20 are respectively pressed against the discharge roller as opposed to the discharge roller as the first roller disposed on the back side of the paper P, and the discharge roller. A discharge roller is provided as a second roller that is disposed and rotates around.

  By the way, as described above, each of the paper feeding mechanism m1, the transport mechanism m2, the image forming mechanism m3, the fixing mechanism m4, and the discharging mechanism m5 receives the rotation from a predetermined driving unit, and the paper P is predetermined. The processing for each mechanism is performed while being transported at a transport speed of.

  When the paper P is transported from the upstream mechanism to the downstream mechanism in the transport direction of the paper P, the slack of the paper P is formed between the upstream mechanism and the downstream mechanism. The transport speed by the downstream mechanism is set lower than the transport speed by the upstream mechanism.

  However, when the left and right slacks in the width direction of the paper P are different between the upstream side mechanism and the downstream side mechanism, for example, between the image forming mechanism m3 and the fixing mechanism m4, If the paper P jumps greatly when it leaves the image forming mechanism m3, the image forming surface of the paper P and the image forming mechanism m3 rub against each other, and the image quality deteriorates.

  FIG. 3 is a first diagram for explaining a phenomenon when left and right slacks are different, and FIG. 4 is a second diagram for explaining a phenomenon when left and right slacks are different.

  In the figure, P is paper, m3 is an image forming mechanism, m4 is a fixing mechanism, 17 is a transfer belt, 18 is a fixing device, 25 is a fixing roller, 26 is a pressure roller, 27 is a driving roller, and 52C is a photosensitive drum. is there.

As described above, in order to form a slack in the paper P, the transport speed of the paper P in the fixing mechanism m4 is set lower than the transport speed of the paper P in the image forming mechanism m3. Therefore, when the peripheral speed of the fixing roller 25 is Vf and the peripheral speed of the drive roller 27 is Vb, the peripheral speeds Vf and Vb are
Vf <Vb
To be.

  By the way, the pressure roller 26 is urged toward the fixing roller 25 from below by a spring (not shown) as an urging member and is pressed against the fixing roller 25. In this case, the springs are disposed at both ends of the shaft of the pressure roller 26. However, if the length of each spring is different or the urging force is different, the left and right pressing forces Nl and Nr are different.

For example, the pressing forces Nl and Nr are
Nl <Nr
The left and right conveyance forces Fl and Fr of the paper P are
Fl <Fr
become.

  As a result, a difference occurs between the left and right transport amounts of the paper P, and tilted slack occurs as shown in FIG.

  Further, when the contact line of the fixing roller 25 and the pressure roller 26 and the axis of the drive roller 27 are not parallel, there is a difference in the distance between the left and right ends of the contact line and the left and right ends of the shaft. . In this case, even if the left and right conveyance forces Fl and Fr of the paper P are equal and the left and right conveyance amounts of the paper P are equal, slanted slack occurs.

  Incidentally, a positive polarity voltage is applied to the transfer belt 17 in order to form a good image, and the paper P is conveyed while being attracted to the transfer belt 17. When the paper P moves away from the driving roller 27 that forms the inflection point of the transfer belt 17, the force generated when the paper P is released from the suction and the force for returning the slack are simultaneously applied. .

  Therefore, as described above, when the left and right slacks in the width direction of the paper P are different, as shown in FIG. 4, when the paper P is separated from the transfer belt 17 in the image forming mechanism m3 on the side where the slack is large. The image formation surface of the paper P and the image formation mechanism m3 rub against each other at a predetermined point in the image forming unit 22C, in this embodiment, the point a on the front edge of the lower surface of the image formation unit 22C. .

  Therefore, a slack correction device u2 (FIG. 2) that detects and corrects slack is disposed between the image forming mechanism m3 and the fixing mechanism m4 so that the left and right slacks in the width direction of the paper P are equal. .

  FIG. 1 is a plan view showing an arrangement state of the slack correction device according to the first embodiment of the present invention, and FIG. 5 is a sectional view showing an arrangement state of the slack correction device according to the first embodiment of the present invention. FIG. 6 is a perspective view showing an arrangement state of the slack correction device according to the first embodiment of the present invention.

  As shown in the figure, a slack correction device u2 is disposed between the driving roller 27 and the fixing device 18 in the conveyance path of the paper P. The slack correction device u2 includes a plurality of locations in the width direction of the paper P, In the present embodiment, correction elements 61L and 61R as first and second correction operation portions are arranged at two locations in the vicinity of both edge portions. For this purpose, a pair of brackets 64L and 64R are provided as support members so as to protrude from the transfer unit support portion (sheet metal) 62 that supports the drive roller 27 toward the fixing device 18, and the brackets 64L and 64R are provided on the brackets 64L and 64R. The correction elements 61L and 61R are supported so as to be swingable around a fulcrum 61a. The correction elements 61L and 61R are disposed inside both edges in the width direction of the paper P with the travel guide 18a interposed therebetween. In the present embodiment, since A4 size paper P is used, the distance between the correction elements 61L and 61R is made smaller than 210 [mm]. In this embodiment, A4 size paper P is used, but paper P of other sizes can be used.

  Each of the correction elements 61L and 61R has a “V” shape, extends from the fulcrum 61a, and protrudes obliquely toward the upstream side and the downstream side in the transport direction of the paper P. The first and second arms am1 and am2 are formed, and the detection unit 61b for detecting the slack state of the paper P is provided at the front end of the first arm am1, and the paper P is provided at the front end of the second arm am2. The correction part 61c for correcting slack according to the slack state is formed.

  As the slack is formed, the detection unit 61b is pushed downward by the paper P, and the correction elements 61L and 61R are rotated in the clockwise direction (the image forming mechanism m3 side) in FIG. It is done. Therefore, in order to urge the correction elements 61L and 61R in the counterclockwise direction (fixing mechanism m4 side) with a predetermined urging force against the pressing force by the paper P, the detection unit 61b is directed upward. A spring 63 as a biasing member is disposed between the brackets 64L and 64R and the detection unit 61b. The detection portion 61b has a horizontal portion in order to hold down the upper end of the spring 63.

  Next, the operation of the slack correction device u2 having the above configuration will be described.

  FIG. 7 is a first diagram showing the operation of the slack correction device in the first embodiment of the present invention, FIG. 8 is a second diagram showing the operation of the slack correction device in the first embodiment of the present invention, FIG. 9 is a third diagram illustrating the operation of the slack correction apparatus according to the first embodiment of the present invention.

  As shown in FIG. 7, the paper P is conveyed from the transfer belt 17 along the travel guide 18 a of the fixing device 18 and enters between the fixing roller 25 and the pressure roller 26. If the slack is generated as the paper P is conveyed, as shown in FIG. 8, the paper P comes into contact with the detection unit 61b, and the correction elements 61L and 61R are rotated in the direction of the arrow to detect. The part 61b is tilted. Further, when the slack increases as the paper P is conveyed, as shown in FIG. 9, the detection unit 61b is further tilted, and the correction elements 61L and 61R are further rotated in the direction of the arrow, and the correction unit 61c is projected upward from the traveling guide 18a and is stopped at a position that balances the pressing force by the paper P on which the slack is formed.

  As a result, the sheet P is lifted upward when passing over the correction unit 61c, and is conveyed in a curved state by the correction unit 61c.

  Next, the operation of the left and right correction elements 61L and 61R of the slack correction device u2 having the above-described configuration will be described.

  FIG. 10 is a diagram showing a first state of the left side portion of the slack correction apparatus according to the first embodiment of the present invention, and FIG. 11 is a first view of the right side portion of the slack correction apparatus according to the first embodiment of the present invention. FIG. 12 is a first view showing the slack state of the paper in the first embodiment of the present invention, and FIG. 13 is a left side portion of the slack correction device in the first embodiment of the present invention. FIG. 14 is a diagram showing a second state, FIG. 14 is a diagram showing a second state in the right side portion of the slack correction apparatus in the first embodiment of the present invention, and FIG. 15 is a sheet in the first embodiment of the present invention. FIG. 16 is a diagram showing a third state of the left side portion of the slack correction apparatus according to the first embodiment of the present invention, and FIG. 17 is a diagram showing the first embodiment of the present invention. 3rd in the right part of the slack correction device in Shows a state, FIG. 18 is a third diagram showing the looseness of the sheet in the first embodiment of the present invention.

  In the figure, 17 is a transfer belt, 25 is a fixing roller, 26 is a pressure roller, 27 is a driving roller, and AR1 is a region where slack is formed. When the left and right slacks are equal in the width direction of the paper P when the paper P is conveyed in the direction of the arrow A, the area AR1 includes the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. It is formed parallel to the axis. At this time, as shown in FIGS. 10 and 11, in each of the correction elements 61L and 61R, the paper P does not contact the detection unit 61b and is not lifted by the correction unit 61c.

  When the left and right slacks differ in the width direction of the paper P, the area AR1 is not formed parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27, as shown in FIG. For example, the left side in the transport direction of the paper P is larger and the right side is smaller. At this time, as shown in FIGS. 13 and 14, the paper P contacts the detection unit 61b at the correction element 61L and is lifted by the correction unit 61c, and does not contact the detection unit 61b at the correction element 61R. It cannot be lifted by the part 61c.

  At this time, as shown in FIGS. 16 and 18, in the left portion of the paper P, a force in the direction of arrow B is applied to the paper P by the amount lifted by the correcting portion 61 c, and the paper P is added to the fixing roller 25. The entry into the pressure roller 26 is delayed.

  As a result, the left and right slacks are equal in the width direction of the paper P, and the area AR1 is formed parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. At this time, as shown in FIGS. 16 and 17, the sheet P is in contact with the detection unit 61b in the correction elements 61L and 61R, and the state where the sheet P is lifted by the correction unit 61c is maintained.

  Thus, in the present embodiment, the left and right slacks in the width direction of the paper P are detected by the detection unit 61b and corrected by the correction unit 61c, so that the left and right slacks can be made equal.

  Further, when the slack in the paper P increases, the paper P is lifted by the correction unit 61c and the slack is reduced, so that when the rear end of the paper P moves away from the driving roller 27, the suction is released. It is possible to reduce the force that is generated and the force that tries to restore slack. Therefore, when the paper P leaves the image forming mechanism m3, it can be prevented from jumping up, and the image forming surface of the paper P and the image forming mechanism m3 can be prevented from rubbing. As a result, the image quality can be improved.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 19 is a schematic view of a printer according to the second embodiment of the present invention, FIG. 20 is a cross-sectional view showing a slack correction device according to the second embodiment of the present invention, and FIG. 21 is a second embodiment of the present invention. The perspective view which shows the slack correction apparatus in a form, FIG. 22 is a top view which shows the slack correction apparatus in the 2nd Embodiment of this invention.

  In this case, a slack correction device u3 is disposed between the driving roller 27 and the fixing device 18 as a fixing device to prevent the paper P as a medium from jumping up. Then, a pair of brackets 64L and 64R as support members are provided so as to protrude from the transfer unit support portion (sheet metal) 62 that supports the drive roller 27 toward the fixing device 18, and each of the brackets 64L and 64R is provided with each of the brackets 64L and 64R. , Correction elements 70L and 70R as first and second correction operation units are disposed, respectively. Each of the correction elements 70L and 70R includes a lever 71 as a first arm and a lever 72 as a second arm formed to protrude toward the downstream side in the transport direction of the paper P. , 72 are supported so as to be swingable about fulcrums 71a, 72a, and are rotated in conjunction with each other. Each of the correction elements 70L and 70R is disposed inside both edges in the width direction of the paper P with the travel guide 18a interposed therebetween. In the present embodiment, since A4 size paper P is used, the distance between the correction elements 70L and 70R is made smaller than 210 [mm].

  The lever 71 has a substantially linear shape, and protrudes toward the lever 72 at a predetermined location, and a protrusion 71b as a first locking portion is in a slack state of the paper P at the tip. The urging portion 71d is formed by causing the detection portion 71c for detecting the protrusion to protrude toward the opposite side of the lever 72 at a predetermined location. Further, the lever 72 has a substantially “L” shape, and in the present embodiment, the lever 72 protrudes toward the lever 71 beside the fulcrum 72a in the second locking position. A protruding portion 72b as a portion is formed at the tip with a correction portion 72c for correcting the slack according to the slack state of the paper P. The protrusions 71b and 72b are selectively locked, and accordingly, the tip of the protrusion 71b is placed on the tip of the protrusion 72b.

  As the slack is formed, the detection unit 71c is pushed downward by the paper P, and the lever 71 is rotated counterclockwise in FIG. Therefore, in order to urge the detection unit 71c upward with a predetermined urging force against the pressing force of the paper P and urge the lever 71 in the clockwise direction, a spring 73 as an urging member is provided in the brackets 64L and 64R. And the urging portion 71d. The urging portion 71d is formed to pull the upper end of the spring 73.

  Further, the lever 72 is rotated in the clockwise direction as the detecting portion 71c is pushed downward by the paper P in the lever 71 and the lever 71 is rotated in the counterclockwise direction. Therefore, the lever 72 is set at the position of the center of gravity so that it is urged counterclockwise by its own weight G against the pressing force of the paper P. When the paper P is not in contact with the detection unit 71c, the protrusions 71b and 72b are not locked. Further, the lever 72 is usually placed at a position where the correction part 72c does not protrude above the travel guide 18a due to its own weight G.

  Next, the operation of the slack correction device u3 having the above configuration will be described.

  FIG. 23 is a first diagram illustrating the operation of the slack correction apparatus according to the second embodiment of the present invention. FIG. 24 is a second diagram illustrating the operation of the slack correction apparatus according to the second embodiment of the present invention. FIG. 25 is a third diagram illustrating the operation of the slack correction apparatus according to the second embodiment of the present invention.

  As shown in FIG. 23, the paper P is conveyed from the transfer belt 17 along the travel guide 18 a of the fixing device 18 and enters between the fixing roller 25 and the pressure roller 26. Then, if slack occurs as the paper P is transported, as shown in FIG. 24, the paper P comes into contact with the detection unit 71c, and the lever 71 is rotated counterclockwise in the figure, The detection unit 71 c is tilted, and accordingly, the projection 71 b is locked with the projection 72 b of the lever 72. Further, when the slack increases as the paper P is conveyed, as shown in FIG. 25, the lever 71 is further rotated counterclockwise, and the lever 72 is rotated clockwise in the drawing. First, the correction part 72c is projected upward from the travel guide 18a, and is stopped at a position that balances the pressing force by the paper P on which the slack is formed.

  As a result, the paper P is lifted upward when passing over the correction portion 72c, and is conveyed in a curved state by the correction portion 72c.

  Next, the operation of the left and right correction elements 70L and 70R of the slack correction device u3 having the above-described configuration will be described.

  FIG. 26 is a diagram showing a first state of the left side portion of the slack correction apparatus according to the second embodiment of the present invention, and FIG. 27 is a first view of the right side portion of the slack correction apparatus according to the second embodiment of the present invention. FIG. 28 is a first view showing the slack state of the paper in the second embodiment of the present invention, and FIG. 29 is a left side portion of the slack correction device in the second embodiment of the present invention. FIG. 30 is a diagram showing a second state, FIG. 30 is a diagram showing a second state in the right side portion of the slack correction device in the second embodiment of the present invention, and FIG. 31 is a sheet in the second embodiment of the present invention. FIG. 32 is a diagram showing a third state in the left side portion of the slack correction apparatus in the second embodiment of the present invention, and FIG. 33 is a second embodiment of the present invention. 3rd in the right part of the slack correction device in Shows a state, FIG. 34 is a third diagram showing the looseness of the sheet in the second embodiment of the present invention.

  In the figure, 17 is a transfer belt, 25 is a fixing roller, 26 is a pressure roller, 27 is a driving roller, and AR1 is a region where slack is formed. When the sheet P is conveyed in the direction of the arrow A and the left and right slacks are equal in the width direction of the sheet P, the area AR1 includes the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. It is formed parallel to the axis. At this time, as shown in FIGS. 26 and 27, in the correction elements 70 </ b> L and 70 </ b> R, the paper P does not contact the detection unit 71 c of the lever 71 and is not lifted by the correction unit 72 c of the lever 72.

  When the left and right slacks are different in the width direction of the paper P, the area AR1 is not formed in parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. For example, the left side in the transport direction of the paper P is larger and the right side is smaller. At this time, as shown in FIGS. 29 and 30, the sheet P comes into contact with the detection portion 71c of the lever 71 in the correction element 70L and is lifted by the correction portion 72c of the lever 72, and the lever P of the lever 71 in the correction element 70R. It does not come into contact with the detection unit 71 c and is not lifted by the correction unit 72 c of the lever 72.

  At this time, as shown in FIGS. 32 and 34, in the left portion of the paper P, a force in the direction of arrow B is applied to the paper P by the amount lifted by the lever 72, and the paper P is pressed against the fixing roller 25. The entry into the roller 26 is delayed.

  As a result, the left and right slacks are equal in the width direction of the paper P, and the area AR1 is formed parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. At this time, as shown in FIGS. 32 and 33, the sheet P is in contact with the detection unit 71c in the correction elements 70L and 70R, and is kept lifted by the correction unit 72c.

  Thus, in the present embodiment, the left and right slacks in the width direction of the paper P are detected by the detection unit 71c and corrected by the correction unit 72c, so that the left and right slacks can be made equal.

  Further, since the lever 71 for detecting slack and the lever 72 for correcting slack are provided, the sensitivity for detecting slack, the position for detecting slack, the position for correcting slack, etc. It can be easily adjusted by changing the ratio.

  In the present embodiment, the lever 72 is biased by its own weight G. However, the lever 72 can be biased by using a spring as a biasing member.

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as the said 1st, 2nd embodiment, the same code | symbol is provided and the effect of the embodiment is used about the effect of the invention by having the same structure.

  FIG. 35 is a schematic view of a printer according to the third embodiment of the present invention, FIG. 36 is a cross-sectional view showing a slack correction device according to the third embodiment of the present invention, and FIG. 37 is a third embodiment of the present invention. The figure which shows the principal part of the slack correction apparatus in a form, FIG. 38 is a perspective view which shows the slack correction apparatus in the 3rd Embodiment of this invention, FIG. 39 shows the slack correction apparatus in the 3rd Embodiment of this invention. FIG.

  In this case, a slack correction device u4 is disposed between the driving roller 27 and the fixing device 18 as a fixing device to prevent the paper P as a medium from jumping up. A bracket 84 as a support member is provided so as to protrude from the transfer unit support portion (sheet metal) 62 that supports the drive roller 27 toward the fixing device 18 side, and extends in the width direction of the paper P. Straightening elements 80L and 80R as first and second straightening operation portions are disposed at the left and right ends of the bracket 84. The correction elements 80L and 80R are arranged on the bracket 84 so as to extend in the width direction of the paper P. The first and second ends 81L and 81R of the lever 81 as a swinging member and the paper P In the vicinity of both ends in the width direction, a pair of levers 82 formed obliquely projecting toward the downstream side downstream of the first and second end portions 81L and 81R in the transport direction of the paper P is formed. Is done. Since the first and second end portions 81L and 81R are formed at both ends of the lever 81, they are rotated in conjunction with each other.

  The levers 81 and 82 are supported so as to be swingable around fulcrums 81a and 82a, and are rotated in conjunction with each other. The fulcrum 81a is disposed in the center in the width direction of the paper P on the bracket 84, and the fulcrum 82a is disposed in the vicinity of both ends in the width direction of the paper P on the bracket 84.

  Each of the correction elements 80L and 80R is disposed inside both edges in the width direction of the paper P with the travel guide 18a interposed therebetween. In the present embodiment, since A4 size paper P is used, the distance between the correction elements 80L and 80R is made smaller than 210 [mm].

  The first and second end portions 81L and 81R have a “h” shape, and in the present embodiment, the first end portions 81L and 81R protrude toward the lever 82 in the vicinity of the lower end. A protruding portion 81b as one locking portion is formed at the tip, a detecting portion 81c for detecting the slack state of the paper P, and an urging portion 81d at the lower end.

  Further, the lever 82 has a substantially “L” shape, and in the present embodiment, beside the fulcrum 82a toward the first and second end portions 81L and 81R. A protruding portion 82b as a second locking portion is formed, and a correction portion 82c for correcting the slack according to the slack state of the paper P is formed at the tip. Then, the projections 81b and 82b are selectively locked, and accordingly, the tip of the projection 81b is placed on the tip of the projection 82b.

  As the slack is formed, the detection unit 81c is pushed downward by the paper P. Therefore, a spring 83 as an urging member is disposed between the bracket 84 and the urging portion 81d in order to direct the detection portion 81c upward with a predetermined urging force against the pressing force of the paper P. .

  As shown in FIG. 37, the lever 81 is disposed on the bracket 84 so as to extend in the width direction of the paper P, and is supported so as to be swingable about a fulcrum 81a. Accordingly, in the correction element 80L, as the detection portion 81c is pushed downward, the first end portion 81L is moved downward, and the lever 81 is rotated clockwise in the drawing to correct the correction element 80R. The second end portion 81R is moved upward, and the second end portion 81R is moved downward as the detection portion 81c is pushed downward. The lever 81 is rotated counterclockwise in the figure. And the first end portion 81L of the correction element 80L is moved upward.

  In addition, the lever 82 has the first and second end portions 81L and 81R that the detection portion 81c is pushed downward by the paper P and the first and second end portions 81L and 81R are moved downward. Along with this, it is rotated clockwise. Therefore, the position of the center of gravity is set so that it is urged counterclockwise by its own weight G against the pressing force of the paper P. When the paper P is not in contact with the first and second end portions 81L and 81R, the protruding portions 81b and 82b are not locked. Further, the lever 82 is usually placed at a position where the correction part 82c does not protrude above the travel guide 18a due to its own weight G.

  Next, the operation of the slack correction device u4 having the above configuration will be described.

  FIG. 40 is a first diagram illustrating the operation of the slack correction apparatus according to the third embodiment of the present invention. FIG. 41 is a second diagram illustrating the operation of the slack correction apparatus according to the third embodiment of the present invention. FIG. 42 is a third diagram illustrating the operation of the slack correction apparatus according to the third embodiment of the present invention.

  As shown in FIG. 40, the paper P is conveyed from the transfer belt 17 along the travel guide 18 a of the fixing device 18 and enters between the fixing roller 25 and the pressure roller 26. If the slack is generated as the paper P is conveyed, as shown in FIG. 41, the paper P comes into contact with the detection unit 81c, and the detection unit 81c is pushed down. 81 b is engaged with the protrusion 82 b of the lever 87. Further, when the slack increases as the paper P is conveyed, as shown in FIG. 42, the detection unit 81c is further pushed down, and accordingly, the correction unit 82c protrudes above the travel guide 18a. Then, it is stopped at a position that balances the pressing force by the paper P on which the slack is formed.

  As a result, the paper P is lifted upward when passing over the correction portion 82c, and is conveyed in a curved state by the correction portion 82c.

  Next, the operation of the left and right correction elements 80L and 80R of the slack correction device u4 having the above-described configuration will be described.

  FIG. 43 is a diagram showing a first state of the left side portion of the slack correction apparatus according to the third embodiment of the present invention, and FIG. 44 shows a first state of the right side portion of the slack correction apparatus according to the third embodiment of the present invention. FIG. 45 is a first view showing the slack state of the paper in the third embodiment of the present invention, and FIG. 46 is a left side portion of the slack correction device in the third embodiment of the present invention. FIG. 47 is a diagram illustrating a second state, FIG. 47 is a diagram illustrating a second state in the right side portion of the slack correction apparatus according to the third embodiment of the present invention, and FIG. 48 is a sheet according to the third embodiment of the present invention. FIG. 49 is a diagram showing a third state of the left side portion of the slack correction apparatus according to the third embodiment of the present invention, and FIG. 50 is a third embodiment of the present invention. 3rd in the right part of the slack correction device in Shows a state, FIG 51 is the third diagram illustrating a third looseness of the sheet in the embodiment of the present invention.

  In the figure, 17 is a transfer belt, 25 is a fixing roller, 26 is a pressure roller, 27 is a driving roller, and AR1 is a region where slack is formed. If the left and right slacks are equal in the width direction of the paper P when the paper P is conveyed in the direction of the arrow A, the area AR1 includes the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. It is formed parallel to the axis. At this time, as shown in FIGS. 43 and 44, in the correction elements 80L and 80R, the paper P does not contact the detection portions 81c of the first and second ends 81L and 81R, and the correction portion 82c of the lever 82. Not lifted by.

  When the left and right slacks are different in the width direction of the paper P, the area AR1 is not formed in parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27, as shown in FIG. For example, the left side in the transport direction of the paper P is larger and the right side is smaller. At this time, as shown in FIGS. 46 and 47, the sheet P comes into contact with the detection portion 81c of the first end portion 81L in the correction element 80L, and is lifted by the correction portion 82c of the lever 82, and in the correction element 80R. The second end portion 81R does not come into contact with the detection portion 81c and is not lifted by the correction portion 82c of the lever 82.

  At this time, as shown in FIGS. 49 and 51, in the left portion of the paper P, a force in the direction of the arrow B is applied to the paper P by the amount lifted by the correcting portion 82c, and the paper P is added to the fixing roller 25. The entry into the pressure roller 26 is delayed.

  As a result, the left and right slacks in the width direction of the paper P become equal, and the area AR1 is formed parallel to the axes of the fixing roller 25, the pressure roller 26, and the driving roller 27 as shown in FIG. . At this time, as shown in FIGS. 49 and 50, the sheet P is in contact with the detection unit 81c of the first end 81L in the correction element 80L, and is kept lifted by the correction unit 82c. At 80R, it does not contact the detection unit 81c and is not lifted by the correction unit 82c.

  Thus, in the present embodiment, the left and right slacks in the width direction of the paper P are detected by the detection unit 81c and corrected by the correction unit 82c, so that the left and right slacks can be made equal.

  In the present embodiment, since the lever 81 is swung in the width direction of the paper P, it is possible to easily detect left and right slack. In addition, since a lever 81 for detecting slack and a lever 82 for correcting slack are provided, the sensitivity for detecting slack, the position for detecting slack, the position for correcting slack, etc. It can be easily adjusted by changing the ratio.

  By the way, if the lever 81 is tilted as much as possible, when the slack is large, one end of the first and second end portions 81L and 81R is pushed downward so that the other end is upward. It is made to protrude greatly. In that case, when the detection portion 81c at the other end is placed at a position higher than the transfer belt 17, the image quality is deteriorated. Therefore, it is preferable to provide a stopper for restricting the swinging of the detection lever 81 so that the detection unit 81c is not positioned higher than the transfer belt 17.

  In each of the above-described embodiments, examples in which the present invention is applied to a printer using the LED heads 21Bk, 21Y, 21M, and 21C have been described. However, the present invention can be applied to a laser printer. Further, the present invention can be applied to an intermediate transfer type printer that uses an intermediate transfer medium between a photosensitive drum and a sheet. Further, the present invention can be applied to a copying machine, a facsimile machine, a multifunction machine, and the like.

  In each of the above embodiments, the slack correction device is disposed between the image forming mechanism m3 and the fixing mechanism m4. However, the slack correction device is disposed between the upstream mechanism and the downstream mechanism. Can be set.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

It is a top view which shows the arrangement | positioning state of the slack correction apparatus in the 1st Embodiment of this invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. It is a 1st figure explaining the phenomenon when right and left slack differs. It is a 2nd figure explaining the phenomenon when right and left slack differs. It is sectional drawing which shows the arrangement | positioning state of the slack correction apparatus in the 1st Embodiment of this invention. It is a perspective view which shows the arrangement | positioning state of the slack correction apparatus in the 1st Embodiment of this invention. It is a 1st figure which shows operation | movement of the slack correction apparatus in the 1st Embodiment of this invention. It is a 2nd figure which shows operation | movement of the slack correction apparatus in the 1st Embodiment of this invention. It is a 3rd figure which shows operation | movement of the slack correction apparatus in the 1st Embodiment of this invention. It is a figure which shows the 1st state in the left side part of the slack correction apparatus in the 1st Embodiment of this invention. It is a figure which shows the 1st state in the right side part of the slack correction apparatus in the 1st Embodiment of this invention. FIG. 3 is a first diagram illustrating a slack state of a sheet in the first embodiment of the present invention. It is a figure which shows the 2nd state in the left side part of the slack correction apparatus in the 1st Embodiment of this invention. It is a figure which shows the 2nd state in the right side part of the slack correction apparatus in the 1st Embodiment of this invention. It is a 2nd figure which shows the slack state of the paper in the 1st Embodiment of this invention. It is a figure which shows the 3rd state in the left side part of the slack correction apparatus in the 1st Embodiment of this invention. It is a figure which shows the 3rd state in the right side part of the slack correction apparatus in the 1st Embodiment of this invention. FIG. 10 is a third diagram illustrating the slack state of the sheet according to the first embodiment of the present invention. It is the schematic of the printer in the 2nd Embodiment of this invention. It is sectional drawing which shows the slack correction apparatus in the 2nd Embodiment of this invention. It is a perspective view which shows the slack correction apparatus in the 2nd Embodiment of this invention. It is a top view which shows the slack correction apparatus in the 2nd Embodiment of this invention. It is a 1st figure which shows operation | movement of the slack correction apparatus in the 2nd Embodiment of this invention. It is a 2nd figure which shows operation | movement of the slack correction apparatus in the 2nd Embodiment of this invention. It is a 3rd figure which shows operation | movement of the slack correction apparatus in the 2nd Embodiment of this invention. It is a figure which shows the 1st state in the left side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is a figure which shows the 1st state in the right side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is a 1st figure which shows the slack state of the paper in the 2nd Embodiment of this invention. It is a figure which shows the 2nd state in the left side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is a figure which shows the 2nd state in the right side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is a 2nd figure which shows the slack state of the paper in the 2nd Embodiment of this invention. It is a figure which shows the 3rd state in the left side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is a figure which shows the 3rd state in the right side part of the slack correction apparatus in the 2nd Embodiment of this invention. It is the 3rd figure showing the slack state of the paper in the 2nd embodiment of the present invention. It is the schematic of the printer in the 3rd Embodiment of this invention. It is sectional drawing which shows the slack correction apparatus in the 3rd Embodiment of this invention. It is a figure which shows the principal part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a perspective view which shows the slack correction apparatus in the 3rd Embodiment of this invention. It is a top view which shows the slack correction apparatus in the 3rd Embodiment of this invention. It is a 1st figure which shows operation | movement of the slack correction apparatus in the 3rd Embodiment of this invention. It is a 2nd figure which shows operation | movement of the slack correction apparatus in the 3rd Embodiment of this invention. It is a 3rd figure which shows operation | movement of the slack correction apparatus in the 3rd Embodiment of this invention. It is a figure which shows the 1st state in the left side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a figure which shows the 1st state in the right side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a 1st figure which shows the slack state of the paper in the 3rd Embodiment of this invention. It is a figure which shows the 2nd state in the left side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a figure which shows the 2nd state in the right side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a 2nd figure which shows the slack state of the paper in the 3rd Embodiment of this invention. It is a figure which shows the 3rd state in the left side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is a figure which shows the 3rd state in the right side part of the slack correction apparatus in the 3rd Embodiment of this invention. It is the 3rd figure which shows the slack state of the paper in the 3rd Embodiment of this invention.

Explanation of symbols

m3 Image forming mechanism m4 Fixing mechanism P Paper u2, u3, u4 Slack correction device

Claims (7)

(A) an upstream mechanism for transporting a medium on which a developer image is formed at a predetermined transport speed and performing a predetermined process;
(B) a medium on which the developer image is formed is conveyed at a conveyance speed lower than the conveyance speed to form a slack of the medium, and a downstream mechanism that performs predetermined processing;
(C) An image forming apparatus, comprising: a slack correction device that is disposed between the upstream mechanism and the downstream mechanism and detects and corrects different slacks in the width direction of the medium.   The image forming apparatus according to claim 1, wherein the slack correction device includes correction operation units formed at a plurality of locations in the width direction of the medium.   The image forming apparatus according to claim 2, wherein each of the correction operation units includes a detection unit that detects different slacks in the width direction of the medium, and a correction unit that corrects the slack.   The image forming apparatus according to claim 3, wherein the detection unit and the correction unit are formed on a lever that is swingably disposed.   The image forming apparatus according to claim 3, wherein the detection unit and the correction unit are formed on separate levers.   The image forming apparatus according to claim 3, wherein the detection units of the correction operation units are rotated in conjunction with each other.   The image forming apparatus according to claim 3, wherein the correction section of each correction operation section is rotated in conjunction with the detection section.

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