JP2024013529A - Opening/closing mechanism and image forming device - Google Patents

Abstract

An object of the present invention is to enable an opening/closing member to be smoothly opened and closed without interference between the tooth tips of a cover side gear and the tooth tips of a device side gear. [Solution] A cover member for opening and closing an opening, a cover side gear disposed on a gear frame 45 attached to the cover member, and a cover side gear disposed rotatably with respect to the device frame. It has a device-side gear that is engaged with the gear, and a moving gear that is movably disposed with respect to the gear frame 45. The teeth of the moving gear have a tooth depth shorter than that of the teeth of the cover-side gear, and when the tooth tips contact the tips of the teeth of the device-side gear, they are retracted to the inside of the pitch circle of the cover-side gear. I am made to do so. When the cover member is closed, the tips of the teeth of the device-side gear hit the middle of the last tooth of the cover-side gear without interfering with the tips of the teeth of the moving gear. [Selection diagram] Figure 1

Description

The present invention relates to an opening/closing mechanism and an image forming apparatus.

Conventionally, in image forming apparatuses such as printers, copying machines, facsimile machines, and multifunction devices, for example, electrophotographic printers, an image forming unit, a transfer device, a fixing device, etc. are installed in the main body of the printer, that is, the device main body. In the image forming unit, the surface of the photosensitive drum uniformly charged by the charging roller is exposed to form an electrostatic latent image, and the electrostatic latent image is developed by the developing roller. A toner image is formed. The toner image is transferred onto paper by a transfer device and fixed on the paper by a fixing device, thereby forming an image and performing printing.

By the way, the top cover, which serves as an opening/closing member of the printer, is opened in order to remove the paper when a paper jam occurs in the apparatus body or to replace a unit such as the fuser. Accordingly, there has been provided a printer in which a fixing device can be attached to and detached from an apparatus main body.

In this printer, the top cover is swingably supported with respect to the printer casing by an opening/closing mechanism, and the top cover is prevented from rapidly closing due to its own weight from an open state. For this reason, in this type of printer, the opening/closing mechanism includes an arc gear as a cover side gear, which is rotatably arranged around the swinging fulcrum of the top cover, and a damper gear as a device side gear. They are engaged, and the closing operation of the top cover is braked (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2006-83551

However, in the opening/closing mechanism of the conventional printer, in order to increase the opening area for attaching and detaching the fuser to the apparatus main body, the swing fulcrum of the top cover is moved as far back as possible within the apparatus main body. Not only is it necessary to position the arc gear, but it is also necessary to have the arc gear as close to the swing fulcrum of the top cover as possible, so the arc gear and damper gear may become disengaged when the top cover is opened. .

In that case, when the top cover is closed, the tips of the teeth of the arc gear and the damper gear interfere with each other as the arc gear and damper gear mesh again, causing tooth skipping and abnormal noise. The top cover cannot be opened and closed smoothly.

The present invention solves the problems of the conventional opening/closing mechanism, and provides an opening/closing mechanism that can smoothly open and close the opening/closing member without interference between the tips of the gears on the cover side and the tips of the gears on the device side. and an image forming apparatus.

To this end, the opening/closing mechanism of the present invention includes a cover member that is swingably supported with respect to the device frame and that opens and closes an opening for attaching and detaching a predetermined unit; a cover-side gear disposed on a gear frame that swings as the device is opened and closed; and a cover-side gear disposed rotatably relative to the device frame and meshed with the cover-side gear to brake the operation of the cover member. It has a device side gear and a moving gear movably disposed with respect to the gear frame.

The teeth of the moving gear have a tooth depth shorter than that of the teeth of the cover side gear, and when the tips of the teeth come into contact with the tips of the teeth of the device side gear, the pitch circle of the cover side gear It is moved further inward.

According to the present invention, the opening/closing mechanism includes a cover member that is swingably supported with respect to the device frame and opens and closes an opening for attaching and detaching a predetermined unit; a cover-side gear disposed on a gear frame that swings as the device is opened and closed; and a cover-side gear disposed rotatably relative to the device frame and meshed with the cover-side gear to brake the operation of the cover member. It has a device side gear and a moving gear movably disposed with respect to the gear frame.

The teeth of the moving gear have a tooth depth shorter than that of the teeth of the cover side gear, and when the tips of the teeth come into contact with the tips of the teeth of the device side gear, the pitch circle of the cover side gear It is moved further inward.

In this case, the tooth depth of the moving gear is made shorter than that of the cover side gear, and when the tooth tip contacts the tooth tip of the device side gear, the pitch circle of the cover side gear is shorter than the pitch circle of the cover side gear. Since it is retracted inward, when the cover member is closed, the tips of the teeth of the device-side gear hit the midpoints of the last teeth of the cover-side gear without interfering with the tips of the teeth of the moving gear.

Therefore, the cover-side gear and the device-side gear start rotating again at their normal meshing positions, so that tooth skipping does not occur, no abnormal noise is generated, and the cover member can be opened and closed smoothly.

Furthermore, even if the opening speed of the cover member changes when the cover member is opened, and variations occur in the position at which the equipment gear is stopped when the moving gear and the equipment gear end their engagement, the cover When the member is closed, the cover-side gear and the device-side gear start rotating again at their normal meshing positions, so tooth skipping does not occur and abnormal noises do not occur.

It is a schematic diagram of the opening and closing mechanism in an embodiment of the present invention. 1 is a conceptual diagram of a printer in an embodiment of the present invention. FIG. 3 is a diagram showing the arrangement of an image forming unit and a fixing device in an embodiment of the present invention. FIG. 1 is a perspective view of a main part of a gear frame in an embodiment of the present invention. 1 is a sectional view of a main part of a gear frame in an embodiment of the present invention. FIG. 3 is a first diagram for explaining the state of the opening/closing mechanism when the top cover is opened in the embodiment of the present invention. FIG. 7 is a second diagram for explaining the state of the opening/closing mechanism when the top cover is opened in the embodiment of the present invention. FIG. 3 is a reference diagram for explaining the state of meshing between the arc gear and the damper gear when the top cover is opened in the embodiment of the present invention. FIG. 6 is a first diagram for explaining the state of the opening/closing mechanism when the top cover is closed in the embodiment of the present invention. FIG. 7 is a second diagram for explaining the state of the opening/closing mechanism when the top cover is closed in the embodiment of the present invention.

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

FIG. 2 is a conceptual diagram of a printer according to an embodiment of the present invention, and FIG. 3 is a diagram showing an arrangement state of an image forming unit and a fixing device according to an embodiment of the present invention. In the figure, the positive direction of the X-axis is the rear direction of the printer 10, the negative direction of the X-axis is the front direction of the printer 10, the positive direction of the Y-axis is the left direction of the printer 10, and the negative direction of the Y-axis is the direction of the printer 10. 10, the Z-axis positive direction is the upward direction in the printer 10, and the Z-axis negative direction is the downward direction in the printer 10.

In the figure, 10 is a printer, and Cs is a housing as an exterior body of the printer 10. The housing Cs includes a front wall Wf, a back wall Wr, a top wall Wt, a bottom wall Wb, a left wall (not shown) disposed on the left side when the printer 10 is viewed from the front wall Wf side, and a front wall Wf side. A right side wall (not shown) is provided on the right side when the printer 10 is viewed from above.

Further, Bd is a main body of the printer 10, that is, a device main body, and a paper cassette 11 as a first medium storage section is disposed in the lower part of the device main body Bd to be detachably attached to the housing Cs. In the paper cassette 11, sheets of paper (also referred to as a recording medium, transfer material, etc.) P as a medium are stored in a stacked manner on a paper feed tray Tr. A first paper feeding mechanism Ms1 is disposed adjacent to the front end of the paper cassette 11, and the first paper feeding mechanism Ms1 is rotatably disposed, and as it rotates, the first paper feeding mechanism Ms1 is placed on the paper feeding tray Tr. A paper feeding sub-roller (pickup roller) 12 as a feeding member that feeds out the uppermost sheet P of the sheets P stacked on the sheet, and a first medium conveyance path for the paper P fed out by the paper feeding sub-roller 12. and a paper feed roller (feed roller) 13 that feeds the paper to the paper transport path Rt1 as a medium transport path for single-sided printing that forms an image on one side of the paper P, and is disposed in contact with the paper feed roller 13. A separating roller (retard roller) 14 is provided as a separating member for separating sheets P one by one. The paper P fed by the first paper feeding mechanism Ms1 is transferred to a pair of transport rollers m1 as a first transport member formed by opposing an intermediate transport roller r1 and a pinch roller p1 in a paper transport path Rt1. After being fed, the skew is corrected by a pair of conveying rollers m2 as a second conveying member formed by opposing the registration roller r2 and the pressure roller p2, and the sheet is conveyed to the image forming section Q1.

A manual feed tray (not shown) serving as a second medium storage section is disposed on the front wall Wf, and, for example, paper P of a paper size that cannot be accommodated in the paper cassette 11 is placed on the manual feed tray. be done. Further, a second paper feeding mechanism Ms2 is disposed adjacent to the front end of the manual feed tray, and the paper P fed by the second paper feeding mechanism Ms2 is skewed by the pair of transport rollers m2. After being corrected, it is sent to image forming section Q1.

The image forming section Q1 includes an image forming unit (ID unit) 30, an LED head 32 as an exposure device, and a photosensitive drum (as an image carrier disposed in the image forming unit 30) via a paper conveyance path Rt1. A transfer roller 34 as a transfer member disposed opposite to the image drum 33 is provided.

When the surface (surface layer portion) of the photoreceptor drum 33 is uniformly charged by a charging roller (not shown) and then exposed to light by the LED head 32 based on image data, latent light is generated on the surface of the photoreceptor drum 33. An electrostatic latent image is formed. Subsequently, when the electrostatic latent image is developed by adhering toner as a developer to the electrostatic latent image by a developing roller (not shown), a predetermined color as a developer image is formed on the surface of the photoreceptor drum 33. For example, a black toner image is formed.

When the paper P transported from the paper cassette 11 through the paper transport path Rt1 and supplied to the image forming section Q1 passes through the transfer section between the photoconductor drum 33 and the transfer roller 34, the paper P is The toner image formed on the photosensitive drum 33 is electrostatically transferred by the electric field formed between the drum 33 and the transfer roller 34 . Note that the transfer roller 34 is formed of, for example, a foamable semiconductive elastic rubber material.

A fixing device (fixing unit) 36 as a fixing device is disposed downstream of the image forming section Q1 in the paper transport path Rt1. The fixing device 36 includes a fixing roller 37 as a first fixing member and a backup roller 38 as a second fixing member. When the paper P supplied to the fixing device 36 passes through the fixing section between the fixing roller 37 and the backup roller 38, the toner image on the paper P is heated by a heating body disposed inside the fixing roller 37. It is heated and melted by a heater (not shown), and is fixed on the paper P by being pressurized by the backup roller 38. The paper P on which the image has been formed in this manner is discharged from the fixing device 36 by a pair of discharge rollers m3 as a third conveyance member formed by disposing a discharge roller r3 and a pinch roller p3 facing each other, and is then discharged from the fixing device 36 through the paper conveyance path. The stacker sk1 is further conveyed along Rt1 and discharged to the outside of the apparatus main body Bd by a discharge roller pair m4, which is a fourth conveyance member formed by opposing a discharge roller r4 and a pinch roller p4, and is formed on the top wall Wt. is discharged.

By the way, in the printer 10 of this embodiment, images can be formed on both sides of the paper P to perform double-sided printing.

For this purpose, the paper transport path Rt1 is branched downstream from a location downstream of the ejection roller pair m3 and adjacent to the ejection roller pair m3, and serves as a second medium transport path and the paper P A paper conveyance path Rt2 is formed as a medium conveyance path for retraction.

In the paper conveyance path Rt2, a pair of retraction rollers m5 as a fifth conveyance member is disposed, and a pair of retraction rollers m6 as a sixth conveyance member is disposed downstream of the pair of retraction rollers m5. Ru.

Further, the paper transport path Rt2 is branched from a predetermined point toward the upstream side, and serves as a third medium transport path for returning the evacuated paper P to the paper transport path Rt1, and as a reversing medium. A paper transport path Rt3 is formed as a transport path.

In addition to disposing a pair of conveying rollers m7 as a seventh conveying member on the sheet conveying path Rt3, a pair of conveying rollers m8 as an eighth conveying member is disposed downstream of the pair of conveying rollers m7. A pair of conveying rollers m9 as a ninth conveying member is disposed downstream of the pair of conveying rollers m8.

Next, the operation of the printer 10 will be explained.

When performing the single-sided printing in which an image is formed on one side of the paper P, the paper P stored in the paper cassette 11 is fed to the paper transport path Rt1 by the first paper feeding mechanism Ms1, and the paper P is fed to the paper transport path Rt1 by the transport roller. The paper is conveyed through the paper conveyance path Rt1 by pair m1, the skew is corrected by conveyance roller pair m2, and then sent to image forming section Q1.

When the paper P passes through a transfer section between the photoconductor drum 33 and the transfer roller 34 in the image forming section Q1, the toner image on the photoconductor drum 33 is transferred, and the toner image is transferred in the fixing device 36. It is fused to form an image on one side.

Subsequently, the paper P is transported along the paper transport path Rt1 by a pair of ejection rollers m3, and is ejected out of the apparatus main body Bd by a pair of ejection rollers m4, and is stacked on a stacker sk1.

On the other hand, when performing double-sided printing in which images are formed on both sides of the paper P, the paper P fed from the paper cassette 11 is transported along the paper transport path Rt1 by the transport roller pair m1, and the paper P is skewed by the transport roller pair m2. The image is corrected and sent to the image forming section Q1.

Then, a toner image is transferred to the paper P in the image forming section Q1, and the toner image is fixed in the fixing device 36, so that an image is formed on one side of the paper P.

Next, the paper P is sent to the paper transport path Rt2 and transported, and then further transported by a pair of retraction rollers m5 and m6, stopped at the retraction position, and then reversed (switched back) to resume the paper transport. The signal is sent to route Rt3. The reversed paper P is transported along the paper transport path Rt3 by transport roller pairs m7 to m9 and returned to the paper transport path Rt1.

Then, the paper P is again transported through the paper transport path Rt1, the toner image is transferred in the image forming section Q1, and the toner image is fixed in the fixing device 36, so that an image is formed on the other side. In this way, the paper P with images formed on both sides is transported through the paper transport path Rt1, ejected from the apparatus main body Bd, and stacked on the stacker sk1.

By the way, in the present embodiment, for example, when a paper jam occurs in the paper P being conveyed within the apparatus main body Bd, the operator removes the paper P or removes the paper P from the image forming unit 30, the fixing device 36, etc. A front cover FC as a first cover member is disposed from above the paper cassette 11 on the front wall Wf to the front end of the top wall Wt, so that the unit on the top wall Wt can be replaced. From the stacker sk1 to the rear, a top cover TC as a second cover member is arranged to be swingable relative to the left and right walls and to be openable and closable. For this purpose, a swinging fulcrum pf of the front cover FC is formed directly above the paper cassette 11 at the front ends of the left and right walls, and the front cover FC is opened and closed by an opening/closing mechanism (not shown) at the rear ends of the left and right walls. A swing fulcrum pt of the top cover TC is formed at the upper end of the top cover TC, and the top cover TC is opened and closed by an opening/closing mechanism Mzt (FIG. 1) to be described later.

Therefore, the operator opens and closes the first opening Mo1 by rotating the front cover FC around the swing fulcrum pf in the direction of the arrow A, and attaches and detaches the image forming unit 30 to the apparatus main body Bd. By rotating the top cover TC in the direction of arrow B about the swing fulcrum pt, the second opening Mo2 can be opened and closed, and the fixing device 36 can be attached to and detached from the apparatus main body Bd.

However, if the top cover TC closes rapidly under its own weight from the open state, there is a risk that the operator's hand may be caught or the opening/closing mechanism Mzt may be damaged. Therefore, in the present embodiment, even if the operator removes his/her hand from the open top cover TC, the opening/closing mechanism Mzt prevents the top cover TC from rapidly closing due to its own weight. There is.

FIG. 1 is a schematic diagram of an opening/closing mechanism according to an embodiment of the present invention, FIG. 4 is a perspective view of a main part of a gear frame according to an embodiment of the present invention, and FIG. 5 is a cross-sectional view of a main part of a gear frame according to an embodiment of the present invention. It is a diagram.

In the figure, Tc is a top cover, Fs is a side frame which is a left device frame that constitutes the inner surface of the left side wall, and Mzt is a side frame that supports the top cover TC so as to be able to swing around a swing fulcrum pt. It is an opening and closing mechanism.

The opening/closing mechanism Mzt includes a pin 41 formed to protrude from the side frame Fs in a direction opposite to the device main body Bd (FIG. 2), and a pin 41 protruded downward from the lower surface of the rear end of the top cover TC. A base portion 43 provided therein, a gear frame 45 that is formed by protruding downward from the base portion 43 and curving in an arc shape and swinging as the top cover TC is opened and closed, and the side frame Fs. An oil damper gear 47 is attached thereto and serves as a braking member that brakes the operation (opening/closing operation) of the top cover TC.

The base portion 43 is formed with a hole h1 into which a pin 41 is inserted, and the top cover TC is swung about a fulcrum point pt via the pin 41.

A circular arc gear gr1 as a cover-side gear is formed on the outer peripheral edge of the gear frame 45, with its rotation center coincident with the swing fulcrum pt. The arc gear gr1 has a plurality of teeth ti (i=1, 2,..., n).

The oil damper gear 47 is attached to the vicinity of the upper edge of the side frame Fs by a screw bt as a fixing member, is meshed with the arc gear gr1, and has a pitch circle radius smaller than the pitch circle radius of the arc gear gr1. It includes a damper gear gr2 as a side gear, and a damper 49 that is disposed adjacent to the damper gear gr2 and rotatably supports the damper gear gr2. The damper 49 is filled with buffering oil and provides resistance to the rotation of the damper gear gr2.

Incidentally, in order to increase the opening area of the second opening Mo2 (FIG. 3) for attaching and detaching the fixing device 36, the swing fulcrum pt of the top cover TC is arranged as far back as possible within the apparatus main body Bd. At the same time, it is necessary to bring the arc gear gr1 as close as possible to the swinging fulcrum pt of the top cover TC. Therefore, when the operator opens the top cover TC, the arc gear gr1 and the damper gear gr2 become disengaged. Sometimes it happens.

In that case, the damper gear gr2 is stopped without rotating at the position immediately after the disengagement, so that when the top cover TC is closed, the arc gear gr1 and the damper gear gr2 mesh again. If the tips of the teeth of the arc gear gr1 and the tips of the damper gear gr2 interfere, tooth skipping may occur and abnormal noise may occur, making it impossible to open and close the top cover TC smoothly.

This is because, at the swing fulcrum pt of the top cover TC, a hole h1 is formed in the base portion 43, a pin 41 is fitted into the hole h1, and a play is provided in consideration of component tolerances. When the top cover TC is opened, the top cover TC moves backward due to the reaction force caused by the meshing of the arc gear gr1 and the damper gear gr2, and when the top cover TC is closed, the top cover TC moves forward. The tips of the teeth of the arc gear gr1 and the tips of the damper gear gr2 interfere with each other. Furthermore, when the top cover TC is opened and the engagement between the arc gear gr1 and the damper gear gr2 is completed, the damper gear gr2 rotates slightly in the opposite direction and the tooth tip returns, so that the tooth tip of the arc gear gr1 and the damper gear gr2 There may be interference with the tips of the teeth.

Therefore, in the present embodiment, a retraction gear gr3 as a moving gear having a fan-like shape is formed in the gear frame 45 at a portion below the lower end of the arcuate gear gr1 (the tip side portion of the gear frame 45). In the space Sp, the damper gear It is arranged so that it can freely mesh with gr2.

Furthermore, one tooth, that is, an engagement tooth tm, is formed at the upper end (end on the top cover TC side) Ue of the outer peripheral edge of the retraction gear gr3 so as to protrude radially outward. The tooth depth representing the distance from the tooth bottom to the tooth tip of the engagement tooth tm is made shorter than the tooth depth from the tooth bottom to the tooth tip of each tooth ti of the circular arc gear gr1.

Then, in a state where only its own weight is applied to the retraction gear gr3 when the top cover TC is closed, the lower end Le of the outer peripheral edge of the retraction gear gr3 is brought into contact with the stopper 53 formed at the lower end in the space Sp. , the engagement tooth tm and the final tooth tn, which is the lowest tooth of the teeth ti of the arc gear gr1, are arranged at a pitch of each tooth ti of the arc gear gr1, as shown in FIGS. 4 and 5. are placed adjacent to each other at a pitch equal to .

On the other hand, when the top cover TC is closed, for example, if the tooth tip of the engaging tooth tm is brought into contact with the tooth tip of a predetermined tooth of the damper gear gr2, the engaging tooth tm is moved into the space Sp. , and is brought close to the final tooth tn, and is also retracted inside the pitch circle of the arc gear gr1.

Next, the state of the opening/closing mechanism Mzt when the top cover TC is opened/closed when the fixing device 36 is attached to and detached from the apparatus main body Bd will be described.

FIG. 6 is a first diagram for explaining the state of the opening/closing mechanism when the top cover is opened in the embodiment of the present invention, and FIG. 7 is a first diagram for explaining the state of the opening/closing mechanism when the top cover is opened in the embodiment of the present invention. FIG. 8 is a reference diagram for explaining the state of engagement between the circular arc gear and the damper gear when the top cover is opened in the embodiment of the present invention, and FIG. 9 is a second diagram for explaining the state of the present invention. A first diagram for explaining the state of the opening/closing mechanism when the top cover is closed in the embodiment of the invention, FIG. 10 is a diagram illustrating the state of the opening/closing mechanism when the top cover is closed in the embodiment of the invention. FIG.

In the figure, Mzt is an opening/closing mechanism, 45 is a gear frame, gr1 is an arc gear, gr2 is a damper gear, and gr3 is a retraction gear.

When the operator slightly opens the top cover TC (FIG. 1) from the closed state shown in FIG. 1 about the pivot point pt, the gear frame 45 fixed to the top cover TC also moves It is rotated by a predetermined amount in the direction of arrow E around the dynamic fulcrum pt. At this time, since the arc gear gr1 and the damper gear gr2 are in mesh with each other, the damper gear gr2 is also rotated by a predetermined amount.

When the arc gear gr1 and the damper gear gr2 mesh, as shown in FIG. 6, the retraction gear gr3 and the damper gear gr2 start meshing.

When the operator further opens the top cover TC, as shown in FIG. 7, the engagement between the retraction gear gr3 and the damper gear gr2 is completed, and after that, the top cover TC is opened with no load being applied to the damper gear gr2. It becomes like this. The damper gear gr2 is stopped at the position shown in FIG. 7 due to the load caused by the oil in the damper 49.

By the way, when the meshing between the retraction gear gr3 and the damper gear gr2 is finished and the damper gear gr2 is stopped, the tooth in the damper gear gr2 that was meshing with the engagement tooth tm of the retraction gear gr3 until just before is tx, and the tooth tx The inclination angle of the line connecting the center of the tooth tip and the rotation center Ctr of the damper gear gr2 is assumed to be θ1.

As shown in FIG. 8, if the retraction gear gr3 as in the present embodiment is not provided, the operator opens the top cover TC and the arc gear gr1 and damper gear gr2 are not engaged with each other. When the damper gear gr2 is stopped and the damper gear gr2 is stopped, the tooth that was meshing with the final tooth tn of the teeth ti of the circular arc gear gr1 until just before is ty, and the center of the tip of the tooth ty and the damper gear gr2 are The inclination angle of the line connecting the rotation center Ctr to the center of rotation Ctr is assumed to be θ2.

In this case, when the inclination angles θ1 and θ2 are compared, the inclination angle θ1 is smaller than the inclination angle θ2 because the tooth depth of the engagement tooth tm is shorter than the tooth depth of the final tooth tn. Therefore, it is possible to prevent the arcuate gear gr1 and the damper gear gr2 from disengaging when the top cover TC is opened.

Furthermore, when the top cover TC is completely opened and the attachment and detachment of the fixing device 36 is completed, the operator closes the top cover TC, which causes the gear frame 45 fixed to the top cover TC to be is rotated in the direction of arrow F.

When the operator closes the top cover TC by a predetermined amount, the tips of the engagement teeth tm of the retraction gear gr3 are brought into contact with the tips of the teeth tx of the damper gear gr2, as shown in FIG.

Subsequently, when the operator further closes the top cover TC, the damper gear gr2 remains stopped at the position shown in FIG. The gear gr3 is rotated about the pin sh1 in the direction of arrow G, and retracts the engagement tooth tm inward from the pitch circle of the arcuate gear gr1.

As a result, the engagement tooth tm and the tooth tx do not mesh, but the final tooth tn and the tooth tx mesh, and the damper gear gr2 is rotated.

At this time, the tip of the tooth tx contacts the midsection between the bottom and the tip of the final tooth tn (the part on the reference pitch line), so the arc gear gr1 and the damper gear gr2 start stable meshing. .

As described above, in the present embodiment, the engagement teeth tm of the retraction gear gr3 have a tooth depth shorter than the tooth depth of the teeth ti of the circular arc gear gr1, and the tooth tips of the engagement teeth tm of the retraction gear gr3 are When the damper gear gr2 comes into contact with the tip of the tooth tx, it is retracted toward the arc gear gr1, so when the operator closes the top cover TC, the tip of the tooth tx of the damper gear gr2 engages with the retraction gear gr3. It hits the middle of the final tooth tn of the arc gear gr1 without interfering with the tooth tip of the mating tooth tm.

Therefore, the arc gear gr1 and the damper gear gr2 start rotating again at the normal meshing position, so there is no tooth skipping, no abnormal noise is generated, and the top cover TC can be opened and closed smoothly. can.

Furthermore, even if the speed at which the top cover TC is opened changes and the position at which the damper gear gr2 is stopped when the engagement between the retraction gear gr3 and the damper gear gr2 is completed varies, the top When the cover TC is closed, the arc gear gr1 and the damper gear gr2 start rotating again at the normal meshing position, so tooth skipping does not occur and abnormal noise does not occur.

Furthermore, since the swing fulcrum pt of the top cover TC can be placed as far back as possible within the apparatus main body Bd, the fixing device 36 can be easily attached and detached.

In the present embodiment, the opening/closing mechanism Mzt is arranged on the left and right walls of the printer 10, but for example, the opening/closing mechanism Mzt is arranged only on the left wall and the opening/closing mechanism Mzt is arranged on the right wall. It is also possible to form only a support structure in which the pin 41 is fitted into the base portion 43.

Further, in this embodiment, the opening/closing mechanism Mzt of the top cover TC has been described, but the present invention can be applied to the opening/closing mechanism Mzf of the front cover FC.

Further, in this embodiment, the printer 10 has been described, but the present invention can be applied to image forming apparatuses such as copying machines, facsimile machines, and multifunction peripherals.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

45 Gear frame FS Side frame gr1 Arc gear gr2 Damper gear gr3 Retraction gear Mo2 Second opening Mzt Opening/closing mechanism TC Top cover ti, tx Teeth tm Meshing teeth

Claims (6)

(a) a cover member that is swingably supported with respect to the device frame and that opens and closes an opening for attaching and detaching a predetermined unit;
(b) a cover-side gear disposed on a gear frame that is attached to the cover member and swings as the cover member opens and closes;
(c) a device-side gear rotatably disposed with respect to the device frame, meshed with the cover-side gear, and braking the operation of the cover member;
(d) a moving gear movably disposed with respect to the gear frame, and
(e) The teeth of the moving gear have a tooth length shorter than that of the teeth of the cover side gear, and when the tips of the teeth abut the tips of the teeth of the device side gear, the pitch of the cover side gear An opening/closing mechanism characterized by being retracted inward from a circle. The opening/closing mechanism according to claim 1, wherein a rotation center of the cover side gear is made to coincide with a swing fulcrum of the cover member. (a) a damper is disposed adjacent to the device side gear;
(b) The opening/closing mechanism according to claim 1, wherein the damper brakes rotation of the device-side gear and operation of the cover member. The opening/closing mechanism according to claim 1, wherein the moving gear is arranged to be swingable with respect to the gear frame, and is rotated and retracted with respect to the gear frame. (a) the cover side gear includes a plurality of teeth formed along the outer peripheral edge of the gear frame;
(b) The opening/closing mechanism according to claim 4, wherein the moving gear is formed adjacent to a final tooth on the distal end side of the gear frame, of the plurality of teeth formed on the gear frame. An image forming apparatus comprising the opening/closing mechanism according to claim 1.

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