JP2004181949A - Screwing device/mounting structure for peripheral machine/image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To contribute to a reduction in size and price of a peripheral machine, and to mount it onto a body without using a tool such as a screwdriver. <P>SOLUTION: A screwing device 10 has a screw shaft 11 and a tab 12, and the tab 12 is movable against the screw shaft 11 in thrust directions and locked in radial directions. The tab 12 is arbitrarily set at a retreat position where its protrusion 12A is engaged with an annular groove 11A and at a drawn-out position where it is engaged with an annular groove 11B. The screwing device 10 is held on a screw storage 5C of a double-sided unit 2 by urging force of a coil spring 13. When screwing, a paper carry guide plate 6 forming a paper carry path 4A is rotated to open the rear end side of the screwing device 10, and the tab 12 is drawn out, pushed in while rotating an operating part 12C and screwed into a screw hole not shown of an image formation device body 1A. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention provides a screw device for fixing a peripheral device such as a duplex unit to a main body such as a main body of an image forming apparatus, a mounting structure of the peripheral device using the screw device, a copying machine having the mounting structure of the peripheral device, The present invention relates to an image forming apparatus such as a printer, a facsimile, a plotter, or a printing machine.

For example, when a double-sided unit as a peripheral device is fixed to a main body of an image forming apparatus with a screw, a configuration as shown in FIG. 19 is conventionally used. As shown in the figure, L-shaped brackets 52, 53 are fixed to left and right side plates 50, 51 of a double-sided unit 54, and ends of the brackets 52, 53 are fixed to an image forming apparatus main body 57 with screws 55. is there.
In FIG. 19, reference numeral 3 denotes a sheet as a sheet-shaped recording medium, and reference numeral 56 denotes a sheet transport guide plate. Reference numeral W1 indicates the width of the double-sided unit 54, and W2 indicates the inner dimension between the left and right side plates 50 and 51. As can be seen from FIG. 19, a screwing portion is provided outside the transport path area of the sheet 3.

As shown in FIG. 20, a configuration is known in which the left and right side plates 50 and 51 are extended and bent outward in an L-shape, and the ends thereof are fixed to the image forming apparatus main body 57 with screws 55. 20, W3 represents the width of the double-sided unit 54, W4 represents the distance between the left side plate 50 and the exterior left side of the double-sided unit 54, W5 represents the distance between the right side plate 51 and the exterior right side of the double-sided unit 54, and W6 represents W7 indicates the gap between the left side plate 50 and the sheet end face, and W8 indicates the gap between the right side plate 51 and the sheet end face. Also in this example, a screwing portion is provided outside the transport path area of the sheet 3.
Further, as shown in FIG. 21, a configuration is known in which the left and right side plates 50 and 51 are extended and bent inward into an L-shape, and the ends thereof are fixed to the image forming apparatus main body 57 with screws 55. In FIG. 21, reference numeral W9 indicates an inner dimension between the left and right side plates 50 and 51. Also in this example, a screwing portion is provided outside the transport path area of the sheet 3.
The screwing (hereinafter, also referred to as "screw tightening") in each of the above configurations is fixed by a serviceman using a tool such as a screwdriver, or fixed without using a tool by a screw member having a knob by a user or a serviceman. Was.

JP-A-9-63399 Patent Publication No. 276865

In the mounting method shown in FIG. 19, since the bracket is fixed via a bracket as a separate member, a considerable strength is required for the bracket, which hinders downsizing of peripheral devices and cost reduction.
In the mounting method shown in FIG. 20, since the mounting portions of the left and right side plates protrude and are exposed to the outside, there is a problem that the quality of the appearance is deteriorated. The left and right plates are generally made of metal, but their fractured surfaces (end end surfaces) rusted with time, and the appearance was poor. The rusted state of the fractured surface can be hidden by plating or the like, but the processing cost will increase the cost.
Further, if the function of attaching the peripheral device is neglected, only the width of W3 is sufficient, but the size of the W1-W3 minute device (including the packing size) becomes large because the attachment portion is on the outside.
In the mounting method shown in FIG. 21, the span between the left and right side plates becomes large, which hinders downsizing of peripheral devices and low cost.

In any of the above-mentioned conventional methods, in the case of a configuration in which a screw is tightened by a knob without using a tool such as a screwdriver, at least a work space enough to allow a finger to be inserted is required, which hinders space saving (miniaturization). I could not avoid becoming.
In a configuration that uses a tool such as a screwdriver to fasten, a relatively small space can be saved because, for example, it is sufficient to secure a work space enough for the bit of the screwdriver, but on the other hand, the screwdriver or the like must be installed on the main body (when mounting). There was a problem that installation was not possible without the necessary tools.
Also, in any of the above methods, if the peripheral device and the main body are positioned, the system operates without tightening the mounting screw, so that the mounting screw may be forgotten to be tightened in some cases. If the operation of the system is continued without being tightened, the danger of causing a serious damage accident cannot be ruled out.

Therefore, the present invention can contribute to downsizing and low price of peripheral devices, and can be attached to a main body without using a tool such as a screwdriver, and a mounting structure for peripheral devices using the screw devices and a screw device. The main purpose is to provide an image forming apparatus having the same.
Further, according to the present invention, even if the screw for fastening the peripheral device and the main body is forgotten, the trouble can be minimized (jam of one sheet of paper), and the operator should be careful not to forget the screw. It is a main object of the present invention to provide a mounting structure of a peripheral device that can be called out and an image forming apparatus having the same.

  To achieve the above object, according to the first aspect of the present invention, a screw shaft having a screw portion screwed into a screw hole at a front end portion, and a screw shaft attached to a rear end portion of the screw shaft to rotate the screw shaft. The screw device has a configuration in which the knob portion is movable in the thrust direction with respect to the screw shaft and is locked in the radial direction.

  According to the second aspect of the present invention, in the screw device according to the first aspect, the knob is temporarily fixed in at least two positions in a thrust direction, ie, a retracted position near the screw portion and a pulled-out position during a rotation operation. The configuration is adopted.

  According to a third aspect of the present invention, in the screw device according to the second aspect, the temporary fixing is performed by snap-fitting the knob by elastically deforming the knob in a recess formed in the screw shaft. I am taking it.

  In the first aspect of the present invention, in the screw device according to the third aspect, the operating force for moving the knob from the pull-out position is greater than the operating force for moving the knob from the retracted position. The configuration is such that the shape of the recess at the pull-out position is set.

  According to a fifth aspect of the present invention, in the screw device according to any one of the second to fourth aspects, the knob has a structure penetrating in a thrust direction, and the knob is temporarily moved to the retracted position. When stopped, the rear end of the screw shaft does not protrude from the rear end surface of the knob.

  According to a sixth aspect of the present invention, there is provided a peripheral device mounting structure for fixing a peripheral device to a main body via a screw device, wherein the screw device according to any one of the first to fifth aspects is used. I am taking it.

  According to a seventh aspect of the present invention, in the peripheral device mounting structure according to the sixth aspect, a screw housing portion for housing the screw device is formed in the peripheral device, and the screw housing portion connects the screw shaft to the main body. The screw device is set to a size such that the knob side of the screw device does not protrude when the knob is returned to the retracted position.

  According to an eighth aspect of the present invention, in the peripheral device mounting structure according to the sixth aspect, a screw housing portion for housing the screw device is formed in the peripheral device, and the screw device is formed in the screw housing portion by an elastic member. A configuration is adopted in which it is biased in the direction of the knob and the position in the direction of the knob is positioned and held.

  According to a ninth aspect of the present invention, there is provided a peripheral device mounting structure for fixing a peripheral device to a main body via a screw device, the screw device having the screw device according to the third aspect, and accommodating the screw device in the peripheral device. A portion is formed, and the screw device is urged by the elastic member in the direction of the knob portion in the screw housing portion, and the position in the direction of the knob portion is positioned and held, and the concave portion in the thrust direction of the screw shaft is formed. A configuration is adopted in which the moving load of the knob between the concave portion and the concave portion is set to be smaller than the urging force of the elastic member.

  In the tenth aspect of the present invention, in the peripheral device mounting structure according to the eighth or ninth aspect, the screw accommodating portion pushes the screw shaft against the biasing force of the elastic member and pushes the screw shaft into the main body side. The size of the screw device is set so that the knob side of the screw device does not protrude when the knob is returned to the retracted position.

  According to an eleventh aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to tenth aspects, in a state where the screw shaft is not screwed to the main body side, a tip of the screw shaft is The peripheral device is provided so as not to protrude from a mounting surface of the peripheral device with respect to the main body.

  According to a twelfth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to eleventh aspects, a large-diameter portion having a radial annular groove is provided on the screw shaft, and The member is a coil spring, and the coil spring is set between the annular groove and the mounting surface for the main body.

  According to a thirteenth aspect of the present invention, in the peripheral device mounting structure of the twelfth aspect, a convex portion is formed in the screw housing portion, and the large diameter portion abuts on the convex portion so that the screw is not screwed. The configuration is such that positioning in the direction of the knob is performed.

  According to a fourteenth aspect of the present invention, in the peripheral device mounting structure according to any one of the sixth to thirteenth aspects, the main body is an image forming apparatus main body, and the screw device is attached to the image forming apparatus main body. The configuration is such that the sheet-shaped recording medium is provided within a range of a width orthogonal to the conveying direction of the used sheet-shaped recording medium.

  According to a fifteenth aspect of the present invention, in the peripheral device mounting structure according to any one of the sixth to thirteenth aspects, the main body is an image forming apparatus main body, and the peripheral device is the image forming apparatus. A double-sided unit having a configuration for inverting the sheet-shaped recording medium when forming images on both sides of the sheet-shaped recording medium used for the main body, and the double-sided unit includes a member that forms a transport path of the sheet-shaped recording medium. The configuration is such that the installation site of the screw device is opened by turning.

  According to a sixteenth aspect of the present invention, in the peripheral device mounting structure of the fifteenth aspect, the screw device is provided within a range of a width orthogonal to a conveying direction of the sheet-shaped recording medium. I have.

  According to a seventeenth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to thirteenth aspects, the main body is an image forming apparatus main body, and the peripheral device is the image forming apparatus. A double-sided unit having a configuration for inverting the sheet-shaped recording medium when forming images on both sides of the sheet-shaped recording medium used for the main body, and the double-sided unit includes a member that forms a transport path of the sheet-shaped recording medium. The screw device is configured to be opened by rotating the screw device, the screw device is provided within a range of a width orthogonal to a conveying direction of the sheet-shaped recording medium, and the screw shaft is connected to the main body side. In a state where the knob is in the retracted position without being screwed to the member, the knob protrudes into the conveyance path of the sheet-shaped recording medium even when the member forming the conveyance path of the double-sided unit is closed. Interfere with the conveyance of the sheet-like recording medium, and employs a configuration that.

  According to an eighteenth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to thirteenth aspects, the main body is an image forming apparatus main body, and the peripheral device is the image forming apparatus. The installation portion of the screw device is opened by rotating a member forming a transport path of the sheet-shaped recording medium used for the main body, and the screw device is orthogonal to the transport direction of the sheet-shaped recording medium. In a state in which the screw shaft is not screwed to the main body side and the knob is in the retracted position, the knob forming the transport path of the peripheral device is closed even when the member forming the transport path of the peripheral device is closed. The portion protrudes into the conveyance path of the sheet-shaped recording medium and hinders the conveyance of the sheet-shaped recording medium.

  According to the nineteenth aspect of the present invention, in the peripheral device mounting structure according to the seventeenth or eighteenth aspect, after the peripheral device has been mounted, if at least the first sheet passing causes a jam, the screw of the screw device is tightened. It has a configuration in which a warning means for warning that the user has forgotten is provided.

  According to a twentieth aspect of the present invention, in the image forming apparatus having the peripheral device mounting structure according to the seventeenth or eighteenth aspect, after the peripheral device has been mounted, if at least the first paper passing causes a jam, the screw device is used. Has a warning means for warning that the screw has been forgotten to be tightened.

  According to a twenty-first aspect of the present invention, the image forming apparatus has a configuration in which any one of the sixth to sixteenth aspects or the peripheral device mounting structure according to the nineteenth aspect is provided.

  According to the invention described in claim 1, 6, or 21, a screw shaft having a screw portion screwed into a screw hole at a front end portion, and a knob mounted on a rear end portion of the screw shaft for rotating the screw shaft. Since the knob has a configuration that is movable in the thrust direction with respect to the screw shaft and is locked in the radial direction, a tool such as a screwdriver is used in a narrow installation space. It can be screwed easily without using.

  According to the invention described in claim 2, 6, or 21, in the screw device according to claim 1, the knob has at least two positions in a thrust direction: a retracted position closer to the screw and a pull-out position during a rotation operation. As a result, it is possible to prevent adverse effects on other members due to inadvertent projection of the knob, and to easily perform the screwing operation.

  According to the third, sixth, or twenty-first aspect of the present invention, in the screw device according to the second aspect, the temporary fixing is such that the knob is elastically deformed and snap-fit into a concave portion formed in the screw shaft. With this configuration, it is possible to easily and reliably perform the temporary fixing operation at the two positions of the knob.

  According to the invention described in claim 4, 6, or 21, in the screw device according to claim 3, the operating force for moving the knob from the pull-out position is higher than the operating force for moving the knob from the retracted position. The configuration is such that the shape of the concave portion at the pull-out position is set to be large, so that it is possible to prevent the knob from coming off the pull-out position due to the pushing force at the time of the screwdriver operation.

  According to the invention described in claim 5, 6, or 21, in the screw device according to any one of claims 2 to 4, the knob has a structure penetrating in a thrust direction. Since the rear end of the screw shaft does not protrude from the rear end surface of the knob when the is temporarily fixed to the retracted position, it is possible to prevent adverse effects on other members due to the protrusion of the screw shaft.

  According to the invention described in claim 7 or 21, in the peripheral device mounting structure according to claim 6, a screw housing portion for housing the screw device is formed in the peripheral device, and the screw housing portion includes the screw shaft. The screw device is screwed to the main body side and the knob portion side of the screw device is set so as not to protrude in a state where the knob portion is returned to the retracted position, so that adverse effects on other members or It is possible to prevent an adverse effect on paper conveyance.

According to the invention as set forth in claim 8 or 21, in the peripheral device mounting structure according to claim 6, a screw housing portion for housing the screw device is formed in the peripheral device, and the screw device is mounted in the screw housing portion. Since the elastic member is configured to be urged in the direction of the knob and positioned and held in the direction of the knob, the peripheral device can be distributed while the screw device is held in advance. The trouble of separately managing the parts of the screw device can be eliminated.
In addition, when the user forgets to tighten the screws, the paper becomes jammed, so that the operator can be urged to tighten the peripheral devices with the screws.

  According to the ninth or twenty-first aspect of the present invention, in a peripheral device mounting structure for fixing a peripheral device to a main body via a screw device, the peripheral device has the screw device according to the third aspect, and the peripheral device has the screw device. A screw accommodating portion for accommodating is formed, and the screw device is urged by the elastic member in the direction of the knob portion and is positioned and held in the direction of the knob portion in the screw accommodating portion, and is held in the thrust direction of the screw shaft. In this configuration, the moving load of the knob between the concave portion and the concave portion is set to be smaller than the urging force of the elastic member. It is possible to reliably prevent the problem caused by biting.

  According to the tenth or twenty-first aspect of the present invention, in the peripheral device mounting structure of the eighth or ninth aspect, the screw accommodating portion moves the screw shaft to the main body side against the urging force of the elastic member. When the screw device is pushed in and screwed down and the knob is returned to the retracted position, the screw device is configured so that the knob side of the screw device does not protrude, so that other members are adversely affected or paper is conveyed. Adverse effects can be prevented.

  According to the invention described in claim 11 or 21, in the mounting structure for a peripheral device according to any one of claims 8 to 10, when the screw shaft is not screwed to the main body, Since the tip of the shaft is provided so as not to protrude from the mounting surface of the peripheral device with respect to the main body, the main body is not damaged by the contact of the screw tip at the time of positioning, and the screw device In this case, it is possible to reliably prevent the screw from re-entrying into the screw hole on the main body after the screw is removed.

  According to the twelfth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to eleventh aspects, the screw shaft is provided with a large-diameter portion having a radial annular groove. Since the elastic member is a coil spring, and the coil spring is set between the annular groove and the mounting surface for the main body, the screw device can be held by a peripheral device with a simple configuration. .

  According to the thirteenth or twenty-first aspect of the present invention, in the peripheral device mounting structure according to the twelfth aspect, a convex portion is formed in the screw housing portion, and the large-diameter portion is abutted against the convex portion to fix the screw. Since the positioning in the direction of the knob is performed in a state where the screw device is not used, the screw device can be held by the peripheral device with a simple configuration.

  According to the invention described in claim 14 or 21, in the peripheral device mounting structure according to any one of claims 6 to 13, the main body is an image forming apparatus main body, and the screw device is the image forming apparatus main body. Since the configuration is provided within the width perpendicular to the conveying direction of the sheet-shaped recording medium used in the forming apparatus main body, it is possible to prevent poor appearance and to reduce the size of peripheral devices.

  According to the invention described in claim 15 or 21, in the peripheral device mounting structure according to any one of claims 6 to 13, the main body is an image forming apparatus main body, and the peripheral device is: A double-sided unit having a configuration for inverting the sheet-shaped recording medium when images are formed on both sides of the sheet-shaped recording medium used in the image forming apparatus main body. Since the installation portion of the screw device is configured to be opened by rotating the member to be formed, the screw device can be easily accessed, and the screwing operation can be facilitated. Can be.

  According to the sixteenth aspect of the present invention, in the peripheral device mounting structure according to the fifteenth aspect, the screw device is provided within a range of a width orthogonal to a conveying direction of the sheet-shaped recording medium. Therefore, inferior appearance can be prevented, and the size of peripheral devices can be reduced.

  According to a seventeenth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to thirteenth aspects, the main body is an image forming apparatus main body, and the peripheral device is the image forming apparatus main body. A double-sided unit having a configuration for inverting the sheet-shaped recording medium when images are formed on both sides of the sheet-shaped recording medium used in the forming apparatus main body, and the double-sided unit forms a transport path of the sheet-shaped recording medium. The installation portion of the screw device is opened by rotating a member, the screw device is provided within a range of a width orthogonal to a conveying direction of the sheet-shaped recording medium, and the screw shaft is provided with the screw shaft. In a state where the knob is in the retracted position without being screwed to the main body side, even if the member forming the transport path of the double-sided unit is closed, the knob protrudes into the transport path of the sheet-shaped recording medium. Since a structure that interferes with the transport of the sheet-like recording medium and can stop damage Forgotten screwing a minimum (jam in the first sheet passing).

  According to an eighteenth aspect of the present invention, in the peripheral device mounting structure according to any one of the eighth to thirteenth aspects, the main body is an image forming apparatus main body, and the peripheral device is the image forming apparatus main body. The installation portion of the screw device is opened by rotating a member that forms a conveyance path of the sheet-shaped recording medium used in the forming apparatus main body, and the screw device is configured to move in a conveying direction of the sheet-shaped recording medium. In the state where the knob is in the retracted position without screwing the screw shaft to the main body side, even if a member forming a transport path of the peripheral device is closed, the screw shaft is not screwed to the main body side. Since the tabs are configured to protrude into the sheet-shaped recording medium conveyance path and hinder the conveyance of the sheet-shaped recording medium, damage caused by forgetting screw tightening can be minimized (jam in initial paper passing). Stop It can be.

  According to the invention described in claim 19 or 21, in the mounting structure of the peripheral device according to claim 17 or 18, when the jam occurs due to at least initial paper passing after the mounting of the peripheral device, the screw device. Is provided with a warning means for warning that the screw has been forgotten to be tightened, so that the operator can be surely and quickly recognized that the screw has been forgotten to be tightened.

  According to the twentieth aspect of the present invention, in the image forming apparatus having the peripheral device mounting structure according to the seventeenth or eighteenth aspect, after the peripheral device is mounted, if at least the first paper passing causes a jam, Since the warning device for warning that the screw of the screw device has been forgotten to be tightened is provided, it is possible for the operator to reliably and quickly recognize that the screw has been forgotten to be tightened.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
First, an outline of the configuration of the image forming apparatus (printer) 1 will be described with reference to FIG. The image forming apparatus 1 has an image forming apparatus main body 1A and a duplex unit 2 as a peripheral device attached to the main body 1A with screws. The image forming apparatus main body 1A includes a sheet feeding device 33, a pair of registration rollers 25, a photosensitive drum 17 as an image carrier, a transfer roller 21 as a transfer unit, a fixing device 24, and the like.
The sheet feeding device 33 includes a sheet feeding tray 34 in which sheets 3 as sheet-shaped recording media are stored in a stacked state, and a sheet feeding roller 26 that feeds the sheets 3 stored in the sheet feeding tray 34 in order from the top. And a separation roller 27 and the like.
The paper 3 sent out by the paper feed roller 26 is temporarily stopped by the pair of registration rollers 25 via the transport path R1, and after the oblique displacement has been corrected, at a timing synchronized with the rotation of the photosensitive drum 17, that is, the photosensitive drum The registration roller pair 25 sends the toner image to the transfer portion at the timing when the leading end of the toner image formed on the sheet 17 and the predetermined position of the leading end in the transport direction of the sheet 3 coincide.

Around the photosensitive drum 17, in the order of rotation indicated by the arrow, a charging roller 18 as a charging unit, an optical writing unit (not shown), a developing device 20, a transfer roller 21, a cleaning device 22, and a photosensitive drum A static elimination lamp 23 for initializing the surface potential 17 is disposed.
Between the charging roller 18 and the developing device 20, an exposure portion on the photosensitive drum 17 is irradiated with a laser beam 19 from the above-mentioned optical writing means and is scanned.

The image forming operation in the image forming apparatus main body 1A is performed in the same manner as in the related art. That is, when the photoconductor drum 17 starts rotating, the surface of the photoconductor drum 17 is uniformly charged by the charging roller 18, and the laser beam 19 is radiated to the exposure unit based on the image information and scanned to form an image to be created. A corresponding electrostatic latent image is formed. The electrostatic latent image is moved to the developing device 20 by the rotation of the photosensitive drum 17, where the toner is supplied by the developing sleeve 20a to be visualized and a toner image is formed.
The toner image formed on the photosensitive drum 17 is transferred at a predetermined timing onto the sheet 3 that has entered the transfer portion by applying a transfer bias by the transfer roller 21.

The paper 3 carrying the toner image is conveyed toward a fixing device 24 having a fixing roller 24a having a heat source therein and a pressure roller 24b pressed against the fixing roller 24a, and is fixed by the fixing device 24 by heat and pressure. The switching claw 30 selectively guides the sheet to the sheet transport path R4 or R5 depending on whether or not the double-side printing has been performed in the print mode. In the case of the single-sided printing mode, the sheet is guided to the sheet transport path R4.
The sheet 3 guided to the sheet transport path R4 is discharged and stacked on a tray (not shown) of the apparatus main body by the discharge roller pair 31. The sheet 3 guided to the sheet conveying path R5 is conveyed by the conveying roller pair 32 to the sheet inlet 2A of the duplex unit 2.
The residual toner remaining on the photosensitive drum 17 without being transferred at the transfer portion reaches the cleaning device 22 as the photosensitive drum 17 rotates, and is scraped off by the cleaning blade 22a while passing through the cleaning device 22. To be cleaned.
Thereafter, the residual potential on the photosensitive drum 17 is initialized by the discharging lamp 23, and is prepared for the next image forming step.

The single-sided printed sheet 3 discharged from the image forming apparatus main body 1A and entering the sheet entrance 2A of the duplex unit 2 passes through an arc-shaped sheet conveyance path 2C continuous to the sheet entrance 2A and a sheet conveyance path 4A. to go into. The paper 3 is transported along a paper transport path 4A by a pair of transport rollers (not shown) (not shown in other paper transport paths), and is transported upward through a paper transport path 4C via a paper reversing unit 4B. After being conveyed by a predetermined distance, the sheet is conveyed again through the sheet reversing section 4B along the sheet conveying path 4D, and enters the image forming apparatus main body 1A from the sheet exit section 2B.
The single-sided printed sheet 3 that has entered the image forming apparatus main body 1 </ b> A is transported along the sheet transport path R <b> 2 by the transport roller pair 29 and heads for the registration roller pair 25. The subsequent image forming process is the same as described above. The sheet 3 on which images are formed on both sides is guided to a sheet transport path R4, and is discharged and stacked by a pair of discharge rollers 31 onto a tray (not shown) on the apparatus body upper surface.

The paper transport path 4A is formed by paper transport guide plates 5, 15 whose positions are fixed, and a rotatable paper transport guide plate 6. The paper transport path 4C is formed by rotatable paper transport guide plates 6 and 7. The paper transport path 4D is formed by a rotatable paper transport guide plate 7 and a paper transport guide plate 15.
The paper transport guide plates 6 and 7 are provided rotatably about fulcrums 6A and 7A, respectively, so that the paper transport paths 4A, 4C and 4D can be opened.
The two-sided unit 2 and the image forming apparatus main body 1A are positioned by a positioning unit (not shown), and are fastened and fixed by a screw device 10 provided in a screw receiving portion 5C of the sheet transport guide plate 5. When attaching the duplex unit 2 to the image forming apparatus main body 1A, first, the duplex unit 2 is dropped from above into the image forming apparatus main body 1A and positioned.

As shown in FIG. 2, the screw devices 10 are provided at two locations within the paper passing range of the paper transport guide surface 5 </ b> A of the paper transport guide plate 5. In other words, the screw device 10 is provided within the range of the width of the sheet in a direction orthogonal to the sheet conveyance direction as the sheet-shaped recording medium. A plurality of ridges 5A-1 for reducing the contact resistance with the paper 3 are formed on the paper transport guide surface 5A at intervals in the paper passing width direction.
The screw device 10 has a screw shaft 11 having a screw portion 11S which is screwed into a screw hole 1B, which will be described later, of the image forming apparatus main body 1A at the front end, and the screw shaft 11 attached to the rear end of the screw shaft 11 to rotate the screw shaft 11. The knob 12 has a configuration that is movable in the thrust direction with respect to the screw shaft 11 and is locked in the radial direction. In this embodiment, the screw shaft 11 is formed in a D-shaped cross section, and the knob 12 has a D-shaped hole.

A plurality of slits 12E are formed in the knob portion 12 in the thrust direction (direction orthogonal to the sheet passing width), and thereby at least one (one in the present embodiment) elastic deformation portion 12B is formed. A large-diameter operation section 12C is formed at the rear end of the knob section 12, and the operation section 12C is subjected to a slip prevention process such as knurling.
The screw device 10 is restricted in the thrust direction by the mounting surfaces 8B, 9B of the left and right side plates 8, 9 and the positioning portion 5B as a convex portion formed in the screw housing portion 5C so that the screw device 10 does not come off. The restriction in the radial direction is performed by the positioning portion 5B. More specifically, the thrust direction is regulated by abutment of the large diameter portion 11C formed on the screw shaft 11 with the mounting surfaces 8B and 9B and the positioning portion 5B. Since the bent portions 8A and 9A of the left and right side plates, which are the intervening members for attachment to the image forming apparatus main body 1A, are located relatively at the back side, they cannot be easily seen, and the appearance quality does not deteriorate. .

As shown in FIG. 3, the screw shaft 11 has an annular groove 11A as a concave portion for temporarily fixing the knob portion 12 at the retracted position, and an annular groove as a concave portion for temporarily fixing the knob portion 12 at the pulled-out position. 11B are formed at intervals in the thrust direction.
Correspondingly, a protrusion 12A is formed on the free end of the elastically deformable portion 12B of the knob 12 so as to engage (snap-fit) with these annular grooves 11A and 11B.
The knob 12 has a structure penetrating in the thrust direction, and when the knob 12 is temporarily fixed to the retracted position (the position where the protrusion 12A is engaged with the annular groove 11A), the rear end 11J of the screw shaft 11 is It is provided so as not to protrude from the rear end surface of the knob portion 12, that is, the rear end surface 12D of the operation portion 12C.
The large-diameter portion 11C of the screw shaft 11 is formed with a radial annular groove 11H opening toward the screw portion 11S, and a coil spring as an elastic member is provided between the annular groove 11H and the mounting surfaces 8B and 9B. (Compression spring) 13 is set.

Even when the screw shaft 11 is not screwed to the image forming apparatus main body 1A side, the screw device 10 is urged toward the knob 12 by the coil spring 13 and the rear end surface 11C-1 of the large diameter portion 11C contacts the positioning portion 5B. As a result, the screw is held in a state where it is prevented from falling off from the screw housing portion 5C. In this holding state, the tip of the screw shaft 11 is set so as not to protrude from the mounting surfaces 8B and 9B. In FIG. 3, reference numerals 8C and 9C denote openings for moving the screw shaft 11 to the image forming apparatus main body 1A side.
Utilizing the holding function of the coil spring 13, as a distribution mode (shipping mode) before the double-sided unit 2 is attached to the main body, a state in which the screw device 10 is set in the screw housing 5 </ b> C in advance is possible. This eliminates the need to separately manage the components of the screw device 10.
Even in the conventional configuration, a nut as a temporary fixing member can be screwed into the set screw 55 and can be circulated integrally. However, when performing screw fixing, an unnecessary nut must be removed, which is troublesome and unnecessary. It is necessary to handle nuts that have become lost.

As shown in FIG. 3, in a state in which the image forming apparatus main body 1A is not screwed,
The knob 12 (strictly, the operation unit 12C) protrudes from the sheet conveyance guide surface 5A of the sheet conveyance guide plate 5 and enters between the sheet conveyance guide surfaces 6B of the sheet conveyance guide plate 6 opposed to each other across the sheet conveyance path 4A.
Therefore, even if the duplex unit 2 is positioned in the image forming apparatus main body 1A and the image forming operation is performed without screwing, the knob 12 blocks the sheet conveying path 4A and hinders the sheet 3 from being conveyed. , Causing paper jam. The measures against paper jam will be described later.
As described above, since the rear end 11J of the screw shaft 11 is provided so as not to protrude from the rear end surface of the knob 12, even if the screw device 10 may come into contact with the paper transport guide plate 6 in some cases. In addition, there is no fear of damaging the sheet conveyance guide plate 6 due to the contact of the rear end 11J of the screw shaft 11, which can be regarded as a small-sized projection member, and it is possible to prevent a conveyance failure such as a jam due to the generation of such a scratch.

When the double-sided unit 2 is fixed to the image forming apparatus main body 1A by the screw device 10, first, as shown in FIG. Then, the sheet transport paths 4C, 4B, and 4D are opened. The paper transport guide plate 7 is prevented from rotating at a predetermined position by a stopper structure (not shown).
Next, similarly, the locked state of the paper transport guide plate 6 by the locking structure (not shown) is released and the paper transport guide plate 6 is rotated to open the paper transport path 4A. The paper transport guide plate 6 is also prevented from rotating at a predetermined position by a stopper structure (not shown).
By the rotation of the paper transport guide plates 7 and 6, the paper transport path 4A is opened, and a screw operation space for the screw device 10 is formed, so that the screw device 10 can be easily accessed.

FIG. 5 shows a state in which the duplex unit 2 is positioned in the image forming apparatus main body 1A, and the knob 12 is pulled out to the pull-out position in order to start the screwing operation by the screw device 10. After the paper transport guide plates 7 and 6 are rotated, a finger is inserted into the screw storage portion 5C of the paper transport guide plate 5, and the knob 12 is pulled out. In this case, the knob 12 is pulled out with a pulling-out force that overcomes the snap-fit force acting between the annular groove 11A and the projection 12A.
When the knob 12 that has come out of the annular groove 11A is pulled toward the rear end as it is, the protrusion 12A snap-fits to the annular groove 11B at the pulled-out position and is temporarily fixed at the pulled-out position.
As shown in FIG. 6, the rear end face 11E of the annular groove 11B rises substantially perpendicularly to the axial direction of the screw shaft 11, and the knob 12 is prevented from being pulled out beyond the pulled-out position. The reason why the knob 12 is held by the annular groove 11A is to prevent a paper jam caused by the knob 12 protruding. The front end face 11K of the annular groove 11A also rises substantially perpendicularly to the axial direction of the screw shaft 11, so that the knob 12 is prevented from being pushed beyond the retracted position.

The tapered surface 11F of the annular groove 11A is set at an angle of about 45 degrees so that the projection 12A can easily come out of the annular groove 11A and can perform predetermined positioning (setting to the retracted position).
By operating the operation part 12C of the knob part 12 pulled out to the pull-out position with a finger, the screw shaft 11 is rotated while being pushed into the screw hole 1B of the image forming apparatus main body 1A, thereby performing screw fixing. That is, the screw can be fixed without using a tool such as a screwdriver.
At the time of screwing, a pressing force in the thrust direction is normally generated, but the tapered surface 11G of the annular groove 11B is set at a steeper angle (about 15 to 30 degrees) than the tapered surface 11F of the annular groove 11A. The knob 12 is prevented from falling out of the annular groove 11B with a pressing force of about one direction.
In other words, the shape of the annular groove 11B at the pull-out position is set such that the operating force for moving the knob 12 from the pull-out position is greater than the operating force for moving the knob 12 from the retracted position.
The urging force of an elastic member (coil spring 13) such as a spring may be made smaller than the force required for the protrusion 12A to be pulled out of the annular groove 11B when the knob 12 is pushed from the drawn position to the retracted position. That is, the operating force required for the protrusion 12A to be disengaged from the annular groove 11B> the biasing force of the elastic member may be satisfied.
With this configuration, the screw can be screwed while the knob 12 is held in the pulled-out position, that is, in a state where the operation unit 12C of the knob 12 is sufficiently protruded from the screw housing 5C, so that the screwing operation is facilitated. .

FIG. 7 shows a state in which the operation part 12C of the knob part 12 is turned to screw the screw part 11S of the screw shaft 11 into the screw hole 1B of the image forming apparatus main body 1A, that is, a state immediately after screwing by the screw device 10. Is shown. The front end face 11C-2 of the large diameter portion 11C comes into contact with the mounting surfaces 8B and 9B, and the coil spring 13 is completely housed in the annular groove 11H of the large diameter portion 11C.
Thereafter, the knob 12 is pushed in with a pushing force that overcomes the snap-fit force acting between the annular groove 11B and the projection 12A, and the knob 12 is positioned at the retracted position as shown in FIGS. . This state is a state in which the screw device 10 is in a paper-passing operation standby state. The knob 12 is fully retracted from the paper transport guide surface 5A of the paper transport guide plate 5, in other words, the knob 12 does not protrude from the screw housing 5C, and the paper transport guide plates 6, 7 are returned to their original positions. Even if the respective sheet transport paths are formed, the knob 12 does not protrude into the sheet transport path 4A, so that the sheet 3 does not get caught on the knob 12 and a paper jam does not occur.
Also, there is a possibility that a hole corresponding to the screw accommodating portion 5C is opened in the sheet transport guide surface 5A, and there is a concern that the guide function of the sheet to be passed is reduced by this amount. However, the taper shown in FIGS. Since the leading end of the sheet is picked up and re-guided by the unit 5D, the sheet is passed without any problem.

Even if the knob 12 is pulled out without tightening the screws, as shown in FIG. 8, the knob 12 jumps out so as to close the paper transport path 4A, and thus a paper jam (jam) occurs at this portion. Thus, the operator can be made aware of forgetting to tighten the screw.
FIG. 8 also shows a state in which the screw unit 10 is loosened to remove the duplex unit 2 from the image forming apparatus main body 1A, the knob 12 is not returned to the retracted position, and then the sheet transport guide plates 6, 7 are closed. FIG. Since the screw device 10 is constantly applied with a force in a direction away from the mounting screw hole 1B of the image forming apparatus main body 1A by the coil spring 13, the tip 11D of the screw shaft 11 re-bites into the screw hole 1B, and the duplex unit 2 is moved. It is prevented from being difficult to remove.

Next, with reference to FIGS. 8 and 9, a countermeasure for jam when the screw is forgotten to be tightened will be described. As shown in FIG. 8, a paper sensor 36 composed of, for example, a transmissive photosensor is disposed on the upstream side in the paper transport direction of a portion where the knob 12 can protrude, and a detection signal from the paper sensor 36 is shown in FIG. Then, it is input to the control means 35 as a main controller of the image forming apparatus main body 1A.
The control means 35 is a microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like. The on state or the off state of the detection signal from the paper sensor 36 is maintained for at least the first paper passing for a predetermined time (depending on the paper size). If the operation continues, it is determined that a paper jam has occurred due to the protrusion of the knob 12, and the liquid crystal display 38 as a warning means of the operation panel 37 displays, for example, "Possibility of forgetting to tighten the duplex unit fixing screw." There is a warning. " The warning may be issued by a warning sound, or may be a combination of a character display and a warning sound.
Upon receiving the warning, the operator turns the sheet conveyance guide plates 7 and 6 of the duplex unit 2 to open the sheet conveyance path, removes the jammed sheet, and then performs the screwing operation of the screw device 10. The warning means may be provided on the duplex unit 2 side.

  The paper sensor 36 may be a reflection-type photo sensor, a mechanical filler sensor, or the like. As a method for judging a jam, a paper sensor 36 is provided on the downstream side of the protruding portion of the knob portion 12, and if the leading end of the paper 3 is not detected within a predetermined time set in advance, a jam due to forgetting to tighten the screw is considered. You may make it determine.

Next, a second embodiment will be described with reference to FIGS. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and the description of the already-described configuration and function will be omitted unless necessary, and only the main part will be described (the same applies to other embodiments described below).
As described above, when the duplex unit 2 screwed and fixed to the image forming apparatus main body 1A is to be removed due to, for example, replacement of parts, the paper transport guide plates 6, 7 are rotated and tilted. First, the knob 12 at the retracted position is pulled out, the screw is loosened while rotating the operation unit 12C, and the screw 11S is removed from the screw hole 1B.
In this state, when the operator returns (closes) the sheet transport guide plates 6 and 7 to the position at the time of the apparatus operation without returning the pulled-out knob 12 to the retracted position with respect to the screw shaft 11 in this state. As shown in FIG. 18, the knob 12 is pushed by the paper transport guide plate 6 so that the tip 11D of the screw shaft 11 hits the screw hole 1B, and then the protrusion 12A comes out of the annular groove 11B and goes to the retracted position. When the frictional force between the outer peripheral surface 11M of the shaft 11 and the projection 12A (moving load of the knob 12) is larger than the urging force of the coil spring 13, the projection 12A of the knob 12 moves to the annular groove 11A of the screw shaft 11. do not do.
That is, the length of the screw device 10 in the thrust direction is increased, and as a result, the state in which the tip 11D of the screw shaft 11 bites into the screw hole 1B is maintained. 2 is difficult to remove from the image forming apparatus main body 1A.

As described above, a pressing force in the thrust direction is usually required at the time of screwing. In order to obtain a pressing force, the elastic deformation portion 12B must exert a holding force (elastic force) such that the protrusion 12A of the knob 12 does not come off (do not move) from the annular groove 11B. However, as a side effect thereof, the frictional force (moving load of the knob 12) when the protrusion 12A moves through the annular groove 11B and moves on the outer peripheral surface 11M of the screw shaft 11 toward the annular groove 11A necessarily increases. This will exceed the biasing force of the coil spring 13.
When the tip 11D of the screw shaft 11 re-enters the screw hole 1B, it is moved in the radial direction of the screw portion 11S (in the direction perpendicular to the axial direction of the screw shaft 11) with respect to the image forming apparatus main body 1A at the time of attachment and detachment. In the required double-sided unit 2 (for example, a type that uses a hook for positioning), the tip 11D is caught in the screw hole 1B and cannot be moved sufficiently, and as a result, the double-sided unit 2 is difficult to remove.
If the operator returns the knob 12 to the retracted position, the above-described problem does not occur. However, it is conceivable that the user pays attention only to the work of loosening the screws and closes the sheet transport guide plates 6 and 7 immediately thereafter.

The main purpose of the present embodiment is to prevent a problem of detachability that may occur when the knob 12 is not returned to the retracted position when the duplex unit 2 is removed for some reason (for example, component replacement). .
As shown in FIG. 10, in the present embodiment, when the paper transport guide plate 6 is returned to the position at the time of operation of the apparatus, in other words, the paper transport guide plate 6 does not interfere with the knob 12 of the screw device 10. In order to prevent the paper transport guide plate 6 from pushing the knob 12, for example, an accommodation recess (escape portion) 6C for accommodating the knob 12 is formed in the paper transport guide plate 6.
Therefore, even if the sheet transport guide plate 6 is closed without returning the knob 12 to the retracted position, the knob 12 is stored in the housing recess 6C without contact. Therefore, the knob 12 does not receive the pressing action of the sheet transport guide plate 6, and the tip 11D of the screw shaft 11 does not re-enter the screw hole 1B.
Since the knob 12 does not contact the paper transport guide plate 6, the screw device 10 does not damage the paper transport guide surface 6B of the paper transport guide plate 6 at all. There is no transport failure such as jam due to the occurrence of scratches.

In the present embodiment, a hole corresponding to the accommodation recess 6C is opened in the paper conveyance guide surface 6B, and there is a concern that the guide function of the paper to be passed is reduced by this amount. Is formed with a tapered portion 6D, which picks up the leading edge of the sheet and guides it again, so that the sheet can be passed without any problem.
Even if the knob 12 is pulled out without tightening the screw, the knob 12 jumps out so as to close the paper transport path 4A. It can be recognized by the operator.
Since the paper transport path 4A is completely closed by the knob 12, the probability of occurrence of a jam is higher than that of the configuration shown in FIG. 3, and it is possible to reliably prevent forgetting to tighten a screw.
FIG. 11 shows a state before the sheet conveyance guide plates 6 and 7 are released and the duplex unit 2 is fixed to the image forming apparatus main body 1A by the screw device 10.

A third embodiment will be described with reference to FIGS.
Similar to the second embodiment, the main purpose of the present embodiment is to prevent a problem of detachability that may occur when the knob 12 is not returned to the retracted position when the duplex unit 2 is removed for some reason. And
In the present embodiment, the moving load of the knob 12 between the annular groove 11B and the annular groove 11A as recesses in the thrust direction of the screw shaft 11, that is, between the pull-out position and the retracted position, is smaller than the urging force of the coil spring 13. It is characterized in that it is set to be small.
As shown in FIG. 12, between the annular groove 11B and the annular groove 11A, a concave portion 11L having a smaller diameter than the outer peripheral surface (maximum outer diameter) 11M of the screw shaft 11 is formed. The concave portion 11L is formed as a groove over the entire circumference, as shown in FIG. FIG. 12 shows a state in which the knob 12 is returned to the retracted position and the sheet transport guide plates 6 and 7 are closed.

As shown in FIG. 13, the formation of the concave portion 11L forms the convex portion 11N between the annular groove 11B and the concave portion 11L, and forms the convex portion 11P between the annular groove 11A and the concave portion 11L. . An inclined surface 11Q is formed between the convex portion 11N and the concave portion 11L so that the elastically deformable portion 12B can smoothly pass over the convex portion 11N when the knob 12 is moved to the pulled-out position. An inclined surface 11R is formed between the concave portion 11L and the concave portion 11L so that the elastically deformable portion 12B can smoothly exceed the convex portion 11P when the knob 12 is moved to the retracted position.
The depth of the concave portion 11L and the annular groove 11B are set to be substantially the same, and the depth of the annular groove 11A is set to be smaller than these.

FIG. 14 shows a state immediately after the screw device 10 is screwed to the image forming apparatus main body 1A in order to attach the duplex unit 2 to the image forming apparatus main body 1A. FIG. 15 shows a state immediately after the screws are loosened to remove the duplex unit 2 from the image forming apparatus main body 1A.
As shown in FIG. 15, when the paper transport guide plate 6 is closed in a state where the knob 12 is in the pulled-out position, the knob 12 is pushed by the paper transport guide plate 6, and the tip 11 </ b> D of the screw shaft 11 becomes a screw hole. 1B, and then the projection 12A comes out of the annular groove 11B and moves to the retracted position.
After the protrusion 12A passes through the convex portion 11N through the annular groove 11B, since the protrusion 12A enters the concave portion 11L, the amount of deformation of the elastic deformation portion 12B decreases. In the present embodiment, the depth of the concave portion 11L is set to a size such that the lower surface of the projection 12A does not contact, and the amount of deformation of the elastically deformable portion 12B is substantially zero.
As a result, the moving load of the knob 12 after the protrusion 12A has passed through the annular groove 11B has only a slight sliding resistance, and the urging force of the coil spring 13 is more effective than the knob 12 caused by deformation of the elastically deforming portion 12B. Will be larger than the moving load.

Therefore, the knob 12 moves to the retracted position while the rear end surface 11C-1 of the large diameter portion 11C of the screw shaft 11 is almost in contact with the positioning portion 5B.
Thereafter, the closing operation of the sheet transport guide plate 6 is completed, and as shown in FIG. 16, the knob 12 stops just before the protrusion 12A passes over the protrusion 11P. At the position where the paper transport guide plate 6 is completely closed, the screw device 10 is pushed so that the rear end surface 11C-1 of the large diameter portion 11C is slightly separated from the positioning portion 5B, but re-bites into the screw hole 1B of the screw portion 11S. Does not occur.
The knob 12 may not be completely located at the retracted position with respect to the screw shaft 11,
The sheet transport path 4A is completely closed, and a jam occurs when the sheet is passed.

In this embodiment, when the paper transport guide plate 6 is closed, the knob 12 comes into contact with the paper transport guide surface 6B. However, if the knob 12 is formed of a synthetic resin having good slidability, a slight amount is obtained. In combination with the state in which the knob 12 is moved by the pushing force, there is no fear of damaging the paper transport guide plate 6.
In the present embodiment, the concave portion 11L is formed as an annular groove in order to reduce the moving load of the knob portion 12, but as shown in FIG. 17B, the milling is performed only at the moving portion of the elastic deformation portion 12B. The same function can be obtained by forming the concave portion 11L-1 by a method such as processing.
In addition, as shown in FIG. 17C, a non-penetrating hole-shaped concave portion 11L-2 may be formed only at the moving portion of the elastically deformable portion 12B, and as shown in FIG. The concave portion 11L-3 having the shape of a circle may be formed. In the case of these recesses 11L-1, 11L-2, and 11L-3, the outer peripheral surface 11M of the screw shaft 11 may be used as a guide when the knob 12 moves in the thrust direction. There is an advantage that play at the time can be reduced.

  The purpose of the present embodiment is not limited to the formation of the concave portion 11L. That is, the magnitude of the moving load of the knob 12 after the protrusion 12A has passed through the annular groove 11B may be smaller than the urging force of the coil spring 13. For example, the contact resistance between the outer peripheral surface 11M of the screw shaft 11 and the protrusion 12A is reduced. It can also be realized by smoothing both surface properties so as to reduce them, or by using a material having extremely low sliding resistance for at least one of the protrusion 12A and the outer peripheral surface 11M.

The width of the double-sided unit 2 as the peripheral device in each of the above embodiments can be corresponded by the dimension of W3 shown in FIG. That is, the size can be reduced by W1-W3 compared to the conventional machine shown in FIGS.
In the above embodiments, the peripheral device is described as a double-sided unit, and the main body is described as the image forming apparatus main body. However, mounting between other peripheral devices and the main body other than the image forming apparatus main body, and other peripheral devices. Can be similarly implemented.

FIG. 1 is a schematic front view of an image forming apparatus according to a first embodiment of the present invention. FIG. 4 is a schematic plan view showing a state where a double-sided unit as a peripheral device is attached to a main body of the image forming apparatus by a screw device. It is a schematic front view which shows the holding | maintenance state of the screw device before screw fastening in a double-sided unit. FIG. 8 is a schematic front view of a state in which a paper conveyance guide plate of the duplex unit is rotated to secure a screw tightening operation space for the screw device. It is a schematic front view which shows the state which pulled out the knob | pick part in order to tighten a screw. It is an outline front view showing a crevice of an evacuation position and a pull-out position in a screw axis of a screw device. FIG. 6 is a schematic front view showing a state where the knob is turned into a screw hole of the image forming apparatus main body from the state shown in FIG. 5. FIG. 4 is a schematic front view showing a state when a screw is forgotten to be tightened. It is a control block diagram. It is a schematic front view showing the holding state of the screw device in the state where the knob before screwing in the second embodiment was pulled out. FIG. 11 is a schematic front view showing a state in which the sheet transport guide plate is released from the state shown in FIG. 10 and a holding state of the screw device before screw tightening. It is a schematic front view showing a holding state of a screw device before screwing in a 3rd embodiment. It is a principal part front view of the screw shaft of the screw device in 3rd Embodiment. It is a principal part front view which shows the state immediately after screwing in 3rd Embodiment. It is an outline front view showing the state where a knob was pulled out and a screw was loosened in a 3rd embodiment. FIG. 16 is a schematic front view showing a state in which the sheet transport guide plate 6 is closed from the state shown in FIG. 15. It is sectional drawing of the screw shaft which shows each structure which reduces the moving load of a knob part. It is a schematic front view for explaining the malfunction when the moving load of a knob part is larger than the biasing force of an elastic member. FIG. 11 is a schematic plan view showing a state in which a duplex unit is attached to a conventional image forming apparatus main body. FIG. 11 is a schematic plan view showing a state in which a duplex unit is attached to a conventional image forming apparatus main body. FIG. 11 is a schematic plan view showing a state in which a duplex unit is attached to a conventional image forming apparatus main body.

Explanation of reference numerals

1A Main body of image forming apparatus as main body 1B Screw hole 2 Double-sided unit as peripheral device 3 Paper as sheet-like recording medium 5B Positioning part as convex part 5C Screw accommodation part 6, 7 Paper transport as member forming transport path Guide plate 8B, 9B Mounting surface 10 Screw device 11 Screw shaft 11A, 11B Annular groove as concave portion 11C Large diameter portion 11H Annular groove 11S Screw portion 12 Knob portion 13 Coil spring as elastic member 38 Liquid crystal display portion as warning means

Claims (21)

  A screw shaft having a screw portion to be screwed into the screw hole at the front end portion, and a knob attached to the rear end of the screw shaft for rotating the screw shaft, wherein the knob is with respect to the screw shaft. A screw device which is movable in the thrust direction and locked in the radial direction. The screw device according to claim 1,
The screw device, wherein the knob is temporarily fixed at least to two positions in the thrust direction, namely, a retracted position near the screw portion and a pull-out position during a rotation operation. The screw device according to claim 2,
The screw device, wherein the temporary fixing is performed by snap-fitting the knob by elastically deforming the concave portion formed in the screw shaft. The screw device according to claim 3,
The shape of the concave portion at the pull-out position is set such that an operating force for moving the knob from the pull-out position is larger than an operating force for moving the knob from the retracted position. Screw device. The screw device according to any one of claims 2 to 4,
A screw device, wherein the knob has a structure penetrating in the thrust direction, and a rear end of the screw shaft does not protrude from a rear end face of the knob when the knob is temporarily fixed to the retracted position. In the mounting structure of the peripheral device fixing the peripheral device to the main body via the screw device,
A peripheral device mounting structure using the screw device according to any one of claims 1 to 5. The peripheral device mounting structure according to claim 6,
A screw accommodating portion for accommodating the screw device is formed in the peripheral device, and the screw accommodating portion is configured such that the screw shaft is screwed to the main body side and the knob is returned to the retracted position. A peripheral device mounting structure, wherein the knob portion side is set so as not to protrude. The peripheral device mounting structure according to claim 6,
A screw accommodating portion for accommodating the screw device is formed in the peripheral device, and the screw device is urged in the screw accommodating portion by the elastic member in the direction of the knob, and is positioned and held in the direction of the knob. Peripheral equipment mounting structure characterized by being carried out. In the mounting structure of the peripheral device fixing the peripheral device to the main body via the screw device,
The screw device according to claim 3, wherein the peripheral device is formed with a screw housing portion for housing the screw device, and the screw device is urged toward the knob by an elastic member in the screw housing portion. The position in the direction of the knob is positioned and held, and the moving load of the knob between the recess and the recess in the thrust direction of the screw shaft is set to be smaller than the urging force of the elastic member. Mounting structure for peripheral equipment. The mounting structure for a peripheral device according to claim 8 or 9,
The screw housing portion pushes the screw shaft into the main body side against the urging force of the elastic member to fix the screw shaft, and the knob portion side of the screw device in a state where the knob portion is returned to the retracted position. A mounting structure for peripheral devices, which is set to a size that does not protrude. The peripheral device mounting structure according to any one of claims 8 to 10,
A mounting structure for a peripheral device, wherein a tip of the screw shaft is provided so as not to protrude from a mounting surface of the peripheral device with respect to the main body when the screw shaft is not screwed to the main body. The mounting structure for a peripheral device according to any one of claims 8 to 11,
The screw shaft is provided with a large diameter portion having a radial annular groove, the elastic member is a coil spring, and the coil spring is set between the annular groove and a mounting surface for the main body. Peripheral equipment mounting structure. The mounting structure for a peripheral device according to claim 12,
A mounting structure for a peripheral device, wherein a convex portion is formed in the screw accommodating portion, and the large-diameter portion abuts on the convex portion to perform positioning in the direction of the knob without screwing. The peripheral device mounting structure according to any one of claims 6 to 13,
Wherein the main body is an image forming apparatus main body, and the screw device is provided within a range of a width orthogonal to a conveying direction of a sheet-shaped recording medium used in the image forming apparatus main body. Construction. The peripheral device mounting structure according to any one of claims 6 to 13,
A duplex unit having a configuration in which the main body is an image forming apparatus main body and the peripheral device is configured to invert the sheet-shaped recording medium when forming images on both sides of the sheet-shaped recording medium used in the image forming apparatus main body; Wherein the double-sided unit has a configuration in which the installation portion of the screw device is opened by rotating a member forming a conveyance path of the sheet-shaped recording medium, and Construction. The mounting structure for a peripheral device according to claim 15,
A peripheral device mounting structure, wherein the screw device is provided in a range of a width orthogonal to a conveying direction of the sheet-shaped recording medium. The mounting structure for a peripheral device according to any one of claims 8 to 13,
A duplex unit having a configuration in which the main body is an image forming apparatus main body and the peripheral device is configured to invert the sheet-shaped recording medium when forming images on both sides of the sheet-shaped recording medium used in the image forming apparatus main body; The double-sided unit has a configuration in which an installation site of the screw device is opened by rotating a member that forms a conveyance path of the sheet-shaped recording medium, and the screw device is configured to rotate the sheet-shaped recording medium. Provided within a width range orthogonal to the transport direction, in a state where the knob is not screwed to the main body side and the knob is in the retracted position, the member forming the transport path of the double-sided unit is closed. The attachment structure for a peripheral device, wherein the knob protrudes into the transport path of the sheet-shaped recording medium to hinder the transport of the sheet-shaped recording medium. The mounting structure for a peripheral device according to any one of claims 8 to 13,
The main body is the main body of the image forming apparatus, and the peripheral device rotates a member forming a conveying path of the sheet-shaped recording medium used in the main body of the image forming apparatus, so that the installation site of the screw device is opened. The screw device is provided within a range of a width orthogonal to the conveying direction of the sheet-shaped recording medium, and the knob is not screwed to the main body side and the knob is in the retracted position. In a certain state, even when a member that forms the transport path of the peripheral device is closed, the knob protrudes into the transport path of the sheet-shaped recording medium and hinders the transport of the sheet-shaped recording medium. Mounting structure. The peripheral device mounting structure according to claim 17 or 18,
A peripheral device having a warning means for warning that the screw of the screw device has been forgotten if at least the first paper feed causes a jam after the peripheral device is attached. Mounting structure. An image forming apparatus having the peripheral device mounting structure according to claim 17 or 18,
An image forming apparatus comprising: a warning unit that warns that the screw of the screw device has been forgotten if at least the first paper feed has caused a jam after the attachment of the peripheral device. apparatus. An image forming apparatus comprising the peripheral device mounting structure according to any one of claims 6 to 16 or claim 19.

Images