Preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.
The composite machine 1 includes a plurality of stages of sheet tray units 3, 4 and 5 which can be drawn out from the front surface of the apparatus main body 2, a manual feed tray 6 provided in the side surface of the apparatus main body 2, an automatic document feeder 7 (hereinafter referred to as “ADF”) used at the time of reading a document by a scanner portion (not shown) serving as a function of each of a copying machine, a facsimile and a scanner, a display screen 8 on which various setting conditions or the like are displayed and which has a panel switch function, and an operating portion 9, for performing operations other than the operation on the display screen 8, or the like. A display screen of a panel switch type is adopted as the display screen 8 so as to make it possible to change the setting of magnification/reduction ratios, and the like. The operating portion 9 includes a start switch, a mode selection switch, a clear switch, a ten-key switch, and the like.
Further, the apparatus main body 2 includes a conveyance path 11 therein, which takes out a transfer sheet (not shown) stored in the sheet tray units 3, 4 and 5, and conveys the transfer sheet toward a paper discharge tray 10. In the apparatus main body 2, a resist sensor 12, a resist roller pair 13, an image forming portion 14, and a fixing device 15 are arranged in order toward the downstream side in the sheet conveying direction from the manual feed tray 6 in the conveyance path 11. A branch path 16 branched from the conveyance path 11 is provided in the downstream side from the fixing device 15.
Further, a switchback path 17, a reverse path 18, and a reverse discharge path 19 are provided in the apparatus main body 2. The switchback path 17 serves to exchange the front and rear of the transfer sheet in the conveying direction, in order to reverse the front and rear surfaces of the transfer sheet conveyed in the branch path 16 (at the time of conveyance). The reverse path 18 is a path serving, when image formation processing is performed to both sides of the transfer sheet, to return the transfer sheet to the conveyance path 11 on the upstream side from the resist sensor 12 after the front and rear of the transfer sheet in the conveying direction is exchanged in the switchback path 17. The reverse discharge path 19 is a path serving, when the front and rear surfaces of the transfer sheet are reversed after image formation, to discharge the transfer sheet from the paper discharge tray 10 after the front and rear of the transfer sheet in the conveying direction is exchanged in the switchback path 17.
The image forming portion 14 includes a photoreceptor drum 20, an electrifying device 21 arranged around the photoreceptor drum 20, an exposing device 22, a developing device 23, a transfer device 24, a cleaning device 25, and the like.
As shown in
A heating member such as a halogen heater 50 is provided in the inside of the fixing roller 26, and the surface of the fixing roller 26 is heated by the heating member. Aluminum, iron or the like is used as the material of the fixing roller 26. Rubber having heat resistance property is used for the pressing roller 27. A pair of rotating bodies according to the claimed invention are constituted by the fixing roller 26 and the pressing roller 27. The present embodiment shows an example in which the separating pawl 28 is made press contact with the fixing roller 26 of the pair of rotating bodies.
In the present embodiment, the separating pawl 28 is constituted by a processed article of a plate shaped member having a spring property. As the plate shaped member, it is possible to use, for example, a metal plate which has a thickness of 0.03 to 0.1 mm, and is made of stainless steel, phosphor bronze, or the like. Further, it is preferred that coating processing of coating or sticking fluororesin is applied to at least the contact surface side with the fixing roller 26.
As shown in
The main body portion 280 and the side portion 282 are separated by a slit processing portion 284 except a tie bar portion 283. In other words, the side portion 282 is connected integrally with the main body portion 280 by the tie bar portion 283 (local connecting portion). The tie bar portion 283 is formed substantially at the central position of the main body portion 280 in the longitudinal direction. The main body portion 280 is in the form in which the leading end portion 28a and the tailing end portion 28b are linearly connected to each other, and the tie bar portion 283 serves as a boundary portion therebetween.
The tip part 281 is formed by applying tapering processing to the end of the leading end portion 28a. The tip part 281 is brought into contact with the surface of the fixing roller 26, so as to be in contact with the transfer sheet which is apt to cling to the fixing roller 26, thereby peeling the transfer sheet. In this case, it is possible to improve the property of peeling the transfer sheet from the fixing roller 26 by the application of the tapering processing. Note that the tapering processing of the tip part 281, the formation of the slit processing portion 284, and the formation of the external shape of the plate shaped member 28′ are realized by, for example, a method of punching out a flat metal plate by using a punching blade and a metallic mold.
The side portion 282 is formed into a hollow cylindrical shape by being wound in a roll shape along the forming direction of the slit processing portion 284, so as to serve as the pivotal portion 28c. For example, it is one of preferred forming processing methods that the side portion 282 is wound in a roll shape, and then the cylindrical shape is fixed by spot-welding the winding end of the cylindrical shape.
Each of the leading end portion 28a and the tailing end portion 28b is a flat plate having a predetermined length, and hence has a spring property as a flat spring. That is, both the leading end portion 28a and the tailing end portion 28b have a spring property which can be restored to a linear shape after being warped in the longitudinal direction of the main body portion 280.
As shown in
For this reason, when the separating pawl 28 is assembled so as to be supported by the shaft 30, the tailing end portion 28b is bent and deformed to generate a spring force. The spring force of the tailing end portion 28b acts as a force of bending and deforming the leading end portion 28a via the pivotal portion 28c. Thus, a spring force is generated in the leading end portion 28a by the bending deformation, so that the tip part 281 is pressed onto the fixing roller 26. On the basis of such mechanism, it is possible to adjust the press-contact force of the tip part 281 to the surface of the fixing roller 26 by the spring property of the tailing end portion 28b.
This means that the press-contact force of the tip part 281 can be adjusted by adjusting the width of the tailing end portion 28b. That is, it is possible to change the press-contact force of the tip part 281 by making the tailing end portion 28b have a portion of a width different from that of the leading end portion 28a, in comparison with the case where the leading end portion 28a and the tailing end portion 28b are made to have the same width as shown in
In this way, the spring strength of the tailing end portion 28b can be adjusted by adjusting the width of the tailing end portion 28b, and hence by cutting and adjusting the width of the tailing end portion 28b at the time of maintenance or the like in the working site, it is possible to set the press-contact force of the tip part 281 in the working site. In the case where such adjustment is to be performed, it is preferred to set the width of the tailing end portion 28b as large as possible in order to extend the adjusting range of the spring strength.
By adjusting the cutout amount of the cutout portion 28d, it is possible to adjust the spring strength of the tailing end portion 28b. When the press-contact force of the tip part 281 is to be set on site, it is preferred to print a plurality of cutout lines 28e for adjusting the cutout amount of the cutout portion 28d, as shown in
As shown in
In the present embodiment, the separating pawl 38 is constituted by a processed article of a plate shaped member having a spring property. As the plate shaped member, it is possible to use, for example, a metal plate which has a thickness of 0.03 to 0.1 mm, and is made of stainless steel, phosphor bronze, or the like. Further, it is preferred that coating processing of coating or sticking fluororesin is applied to at least the contact surface side with the fixing roller 26.
As shown in
The separating pawl 38, whose main body portion is formed by connecting the leading end portion 38a to the tailing end portion 38b in the same width and in the linear state similarly to the separating pawl in embodiment 1 shown in
The manner of assembling the separating pawl 38 to the case 39 is the same as that shown in
For this reason, when the separating pawl 38 is assembled so as to be supported by the shaft hole 39a, the tailing end portion 38b is bent and deformed to generate a spring force. The spring force of the tailing end portion 38b acts as a force of bending and deforming the leading end portion 38a via the shaft 38c. Thus, a spring force is generated in the leading end portion 38a by the bending deformation, so that the tip part 381 is pressed onto the fixing roller 26. On the basis of such mechanism, it is possible to adjust the press-contact force of the tip part 381 to the surface of the fixing roller 26 by the spring property of the tailing end portion 38b.
Similarly to embodiment 1, the press-contact force of the tip part 381 can be adjusted by adjusting the width of the tailing end portion 38b.
There is shown a specific example of the size of the separating pawl 38 in which the width of the tailing end portion 38b is increased as compared with the width of the leading end portion 38a, as in the separating pawl 38 shown in
Referring to
In this case, the transfer sheet is sent by the sheet conveying roller during a time period until the resist roller pair 13 starts to be rotated, and thereby buckled in the conveyance path 11 (the leading edge side of the transfer sheet is partially bent and deformed). As a result, the skew feed is corrected by the buckling. Then, the rotation of the resist roller pair 13 is started at the timing when the image formed on the surface of the photoreceptor drum 20 becomes coincident with the leading edge of the transfer sheet, so that the transfer sheet is sent into the transfer position between the photoreceptor drum 20 and the transfer device 24 by the resist roller pair 13.
In the image forming portion 14, the photoreceptor drum 20 is rotatably driven at a predetermined process speed (circumferential speed) by a drive mechanism (not shown), and the surface of the photoreceptor drum 20 is uniformly charged to a predetermined polarity and an electric potential by the electrifying device 21.
After the photoreceptor drum 20 is electrostatically charged, an electrostatic latent image is formed on the surface of the photoreceptor drum 20 by the exposing device 22. Here, the exposing device 22 performs rasterization on the basis of, for example, image data read by the copying machine function of the scanner portion using the ADF 7, image data received by the facsimile function via a telephone line, and image data outputted by the printer function from a personal computer or the like connected via a communication line such as a network.
Further, the exposing device 22 irradiates laser beam onto the surface of the photoreceptor drum 20 on the basis of the rasterizing information, and forms an electrostatic latent image corresponding to the image information by removing the electric charges of the parts irradiated by the laser beam. A toner having an electric charge is electrostatically stuck to the electrostatic latent image formed on the surface of the photoreceptor drum 20 by the developing device 23, so that the electrostatic latent image is developed as a toner image. The toner image stuck to the surface of the photoreceptor drum 20 is transferred to a transfer sheet as a transfer image by the transfer device 24. Here, in the photoreceptor drum 20 whose toner image formed thereon was transferred to the transfer sheet, the residual toner and the like is removed by the cleaning device 25, and the residual electric charges are removed for the electrostatic charging at the time of next image formation.
Here, in the case when one-surface printing is performed to the transfer sheet, the transfer sheet is sent to the fixing device 15 (15A), so that the toner image is fixed. The transfer sheet sent out from the fixing device 15 (15A) is conveyed along a sheet discharge path, while being peeled by the separating pawl 28 (38, 48), and discharged on the paper discharge tray 10 by a sheet discharge roller.
In the case where the double-surface printing is performed to the transfer sheet, the transfer sheet sent out from the fixing device 15 is guided into the branch path 16. The transfer sheet guided into the branch path 16 is sent into the switchback path 17, with the leading edge side of the transfer sheet placed on the front side, and then sent out to the reverse path 18 from the switchback path 17, with the trailing edge of the transfer sheet placed on the front side. Thereby, the front and rear surfaces of the transfer sheet are reversed.
The transfer sheet whose front and rear surfaces are reversed is returned to the conveyance path 11 from the reverse path 18. Thereafter, similarly to the case of the above described one-surface printing, the transfer sheet is conveyed by the sheet conveying roller and the resist roller pair 13, and an image is formed on the other surface as the unprinted surface through the image forming portion 14 and the fixing device 15, so that the double-surface printing is completed. Thereafter, the transfer sheet subjected to the double-surface printing is conveyed as it is in the conveyance path 11, so as to be discharged on the paper discharge tray 10.
Note that when the above described transfer sheet subjected to the one-surface printing is discharged on the paper discharge tray 10 in the state where the front and rear surfaces of the transfer sheet are reversed, the transfer sheet discharged from the fixing device 15 is sent to the reverse path 18 via the branch path 16. Then, the transfer sheet is sent into the switchback path 17, with the leading edge side of the transfer sheet placed on the front side, and then discharged on the paper discharge tray 10 via the reverse discharge path 19, with the trailing-edge side of the transfer sheet placed on the front side.
The transfer sheet subjected to the image formation processing is discharged on the paper discharge tray 10. When there is no next image formation processing, the drive of each drive system, and the like, is stopped after the lapse of a predetermined time period from when the trailing-edge of the transfer sheet is detected by the resist sensor 12.
As described above, in the fixing device 15 (15A) according to the present embodiment, the tailing end portion of the separating pawl 28 (38, 48) is directly rotatably supported to the case 29(39) without being stuck and fixed to the thin-walled bracket or the like. This makes it possible to reduce the number of components, and to facilitate the mounting work of the separating pawl 28 (38, 48) at the time of assembling the composite machine 1, or the like, as a result of which the versatility can be improved.
Further, it is possible to realize common use of the separating pawl 28 (38, 48), and also to realize simplification of the control of inventory, or the like, by enabling adaptation of the separating pawl in the working site.
Further, since the separating pawl 28 (38, 48) is directly rotatably supported by the case 29(39), even when the separating pawl 28 (38, 48) needs to be exchanged during the maintenance work, it is possible to easily exchange the separating pawl 28 (38, 48) on the spot. Therefore, the versatility can be improved also from the viewpoint of maintenance or the like.
According to the invention, the following modifications may be made.
[1] In the above described embodiment, the composite machine 1 is explained as an example of the image forming apparatus to which the fixing device 15 according to the present invention is applied. Alternatively, it is of course possible to apply the present invention to various dedicated machines such as a copying machine, a printer and a facsimile.
[2] As the fixing device 15 (15A) of the above described embodiment, the fixing device using the fixing roller 26 and the pressing roller 27 is explained. In addition, for example, as shown in
[3] Further, as shown in
[4] Further, as shown in
[5] In the above described embodiments, there are shown examples in which the present invention is applied to the fixing device. In addition to these, the present invention is applicable to various sheet conveying devices. For example,
The conveying belt 141 is stretched over a plurality of rollers 142, 143 and 144, and conveys a sheet P by making the sheet electrostatically attracted onto the outer peripheral surface of the belt. A toner image of each color respectively formed by the image forming unit of each color is successively applied on the sheet P in an overlapped state. Then, the sheet P on which a color toner image is formed, is guided to the nip portion of the fixing roller 26 and the pressing roller 27, so as to be subjected to the fixing processing.
The separating pawl 28 is made press contact with the outer peripheral surface of the conveying belt 141 at a position of the inlet side of the fixing roller pair. Here, the separating pawl 28 performs a function of separating the sheet P electrostatically attracted to the outer peripheral surface of the conveying belt 141, and surely guiding the sheet P to the fixing roller pair.
[6]
In the sheet conveying device, when a sheet P with low stiffness, such as a thin sheet, is conveyed, the sheet P is liable to be wound around the conveyance roller 145. The separating pawl 28 contributes to prevent the winding beforehand, and to realize smooth conveyance of the sheet P.
It will be seen that the foregoing embodiments and modifications mainly have the following inventive features.
A fixing device comprises: a pair of rotating bodies forming a nip portion, for fixing an image formed on a surface of a sheet; and a separating pawl having a leading end portion and a tailing end portion, a tip part of the leading end portion being made press contact with a surface of at least one of the pair of rotating bodies, and having a pivotal portion integrally formed between the leading end portion and the tailing end portion. The tailing end portion has a spring property capable of adjusting press-contact force of the tip part.
Also, an image forming apparatus comprises: an image forming portion adapted to perform transfer processing to transfer a toner image onto a sheet; and a fixing portion adapted to perform fixing processing of the toner image by heating the sheet. The fixing portion is provided with the constitution of the above-mentioned fixing device.
According to these constitutions, it is possible to adjust the press-contact force of the tip part to the rotating body surface by the spring property of the tailing end portion. Further, the separating pawl is not fixedly supported, but is supported by the pivotal portion. This makes it possible to reduce the number of components, and to facilitate the mounting work of the separating pawl. Accordingly, the versatility can be improved.
The leading end portion may be preferably made to have a spring property. Accordingly, it is possible to effectively transmit the spring property of the tailing end portion to the tip part.
The pivotal portion may be preferably formed in a shape of bearing, or in a shape of shaft.
The separating pawl may be preferably made of a plate shaped member, which includes a main body portion forming the leading end portion and the tailing end portion which are connected with each other straightly, and side portions arranged at both sides of the main body portion for constituting the pivotal portion. According to the constitution, it is possible to easily form the separating pawl by using the plate shaped member.
The side portion may preferably have a predetermined length in a longitudinal direction of passing the leading end portion and the tailing end portion, and be integrated with the main body portion by a local connecting portion, so that a bearing-shaped pivotal portion can be formed by making the side portion processed into a cylindrical shape.
The tailing end portion may be preferably adapted to include a portion having a width different from that of the leading end portion. According to the constitution, it is possible to adjust the spring force of the tailing end portion by the width size of the tailing end portion.
It may be appreciated that the leading end portion has a first width as a whole except the tip part, and the tailing end portion has a second width which is narrower than the first width as a whole, or which is wider than the first width as a whole.
Alternatively, it may be appreciated that the tailing end portion has a cutout portion formed by cutting a part of the tailing end portion in the width direction. According to the constitution, it is possible to adjust the spring force of the tailing end portion by the degree of cutting of the tailing end portion.
The side portion may be preferably made to have a predetermined projecting length in a direction perpendicularly intersecting the longitudinal direction of passing the leading end portion and the tailing end portion, and to be integrated with the main body portion in the longitudinal direction as a whole, thereby forming a shaft-shaped pivotal portion. The constitution has an advantage that the pivotal portion can be formed without the need to specifically process the side portion.
It may be appreciated that the leading end portion has a length extending over substantially the whole width of the rotating body, and the tailing end portion has a plurality of segments integrally formed with the leading end portion.
A sheet conveying device comprises: a conveying body having a rotating conveying surface capable of conveying a sheet in a close contact state; and a separating pawl having a leading end portion and a tailing end portion, a tip part of the leading end portion being made press contact with the conveying surface of the conveying body, and having a pivotal portion integrally formed between the leading end portion and the tailing end portion. The tailing end portion has a spring property capable of adjusting the press-contact force of the tip part.
The conveying body may be preferably a rotating conveying belt which is stretched over a plurality of rollers. Also, the conveying body may be preferably a conveying roller which is rotated around an axis.
This application is based on patent application No. 2006-208795 filed in Japan, the contents of which are hereby incorporated by references.
As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to embraced by the claims.
Number | Date | Country | Kind |
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2006-208795 | Jul 2006 | JP | national |