JP2525231B2 - Image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus such as an electrostatic copying apparatus.

(Conventional technology and its disadvantages)

Generally, an image forming apparatus includes a rotating drum having a photoconductor on its surface. In the case where the rotary drum is directly mounted on the main body of the image forming apparatus, when the rotary drum is mounted, the driven gear provided at one end of the rotary drum is driven by the drive linkage gear provided on the main body of the apparatus. It is designed to be connected. Further, in a configuration in which the rotary drum is mounted on the unit frame and the unit frame is mounted on the apparatus body, when the unit frame is mounted on the apparatus body in the state where the rotary drum is mounted on the unit frame, one end of the rotary drum is The driven gear provided is drive-coupled to the drive connecting gear provided in the main body of the apparatus.

However, the conventional image forming apparatus has the following problems to be solved. That is, the receiving means for supporting the shaft portion of the rotary drum has conventionally defined a U-shaped receiving surface whose upper surface is open. Therefore, if the direction of action of the transmission force transmitted from the driving connection gear to the driven gear is slightly higher than the horizontal direction, the action of the transmission force causes the shaft of the rotating drum to separate from the receiving surface. A tendency,
Thus, it is difficult to reliably hold the shaft of the rotating drum at a predetermined position.

Further, in the conventional image forming apparatus, the rotary drum is only rotated in the predetermined direction by the action of the electric motor. Therefore, when the rotation of the electric motor is stopped after the completion of image formation, the drive coupling gear and the driven gear are in a sufficiently meshed state, and therefore, this rotary drum is used for replacing the rotary drum, for example. When detaching the unit frame from the main body of the apparatus, the unit frame cannot be easily detached.

[Object of the Invention]

The present invention has been made in view of the above facts, and its main object is to provide an improved image forming apparatus capable of reliably supporting the shaft portion of a rotary drum.

Another object of the present invention is to provide an improved image forming apparatus in which the rotary drum can be easily detached from the apparatus main body or the unit frame on which the rotary drum is mounted can be easily detached from the apparatus main body.

[Outline of Invention]

In the image forming apparatus of the present invention, the receiving means for supporting one shaft portion on the driven gear side of the rotary drum defines a substantially semicircular receiving surface that covers a part of the upper portion of the upper shaft portion, and drives the shaft. The power transmitted from the connecting gear to the driven gear is supported by the receiving surface of the receiving means. Therefore, the transmission force from the drive connecting gear is surely supported on the receiving surface of the receiving means via the shaft portion, and the tendency of the shaft portion to be biased upward by the power transmission is determined by the receiving surface of the receiving means. Therefore, the shaft portion of the rotary drum can be securely held in a predetermined position with a relatively simple structure.

Further, in the image forming apparatus of the present invention, after the drive of the drive source is stopped, the drive source is rotated somewhat in the direction opposite to the rotating direction at the time of image formation. Therefore, the meshing state of the drive connecting gear and the driven gear is released by the rotation in the direction opposite to the drive source, which facilitates the release of the connection between the drive connecting gear and the driven gear, and thus the rotary drum is installed in the device. The unit frame can be easily detached from the main body of the apparatus by mounting the rotary drum on the main body.

[Specific Examples of Invention]

 Hereinafter, a detailed description will be given with reference to the accompanying drawings.

Outline of Laser Beam Printer FIG. 1 shows a specific example of a laser beam printer as an example of an image forming apparatus according to the present invention. In FIG. 1, the illustrated laser beam printer includes an apparatus main body 2, and the apparatus main body 2 includes a lower housing 4 and an upper opening / closing housing 6 which is attached to the lower housing 4 via a shaft member 5 so as to be openable and closable. ing. The upper opening / closing housing 6 is rotatable between a closed position shown by a solid line in FIG. 1 and an open position shown by a chain double-dashed line.

At a substantially central portion of the apparatus main body 2, a process unit 8 is provided. The illustrated process unit 8 includes a unit frame 10 that is detachably mounted in the apparatus main body 2, and a rotary drum 12 is rotatably mounted in the unit frame 10.
An electrostatic photoconductor is provided on the peripheral surface of the rotary drum 12. The support structure of the rotary drum 12 will be described later. Around the rotating drum 12 which is rotated in the direction indicated by the arrow 14, a charging corona discharger 16, a developing device 18, a transfer corona discharger 20 and a cleaning device 22 are provided, and the charging corona discharger 16, The developing device 18 and the cleaning device 22 are provided in the unit frame 10.

An optical unit 24 is arranged in the upper part of the apparatus main body 2, that is, above the process unit 8. The illustrated optical unit 24 includes a box-shaped unit housing 26, and the unit housing 26 is mounted on the inner surface of the upper opening / closing housing 6. In the housing 26, a laser light source (not shown) and a rotary polygonal mirror 2 which is rotated in a predetermined direction.
8, imaging lens 30, first reflecting mirror 34 and second reflecting mirror 36
Are arranged. A laser light source (not shown) irradiates the rotary polygon mirror 28 with laser light based on image information output from a computer, for example. The laser light reflected from the rotary polygon mirror 28 passes through the imaging lens 30 to reach the first reflecting mirror 34, as shown by the alternate long and short dash line in FIG. 1, and the first reflecting mirror 34 and the second reflecting mirror 34 are reflected. After being reflected by the mirror 36, the rotating drum 12
Projected on the surface of.

At the lower part of the apparatus main body 2, that is, below the process unit 8, a transport mechanism generally designated by the numeral 42 is arranged.
The illustrated conveyance mechanism 42 includes a conveyance roller pair 44, a guide pair 46, and a guide plate.
48, a fixing roller pair 50 and a first discharge roller pair 52,
These define a transport path 54 for transporting a sheet member such as recording paper. In the specific example, the upstream end of the transport path is 2
Is divided into two, one of which extends straight to the right,
A manual feeding means 56 is arranged at the upstream end.
The other side is curved and extends downward, and an automatic supply means 58 is provided at the upstream end (specifically, below the transport mechanism 42 and the bottom portion inside the apparatus main body 2). The illustrated manual feed means 56 is provided with a table 60 which is rotatable between the supply position shown in FIG. 1 and a storage position (not shown) which is swung upward, and the manual feed means 56 is used. When this is done, the table 60 is positioned at the supply position. When the sheet member is positioned on the table 60 and inserted through the opening 62 formed in the right side surface of the apparatus main body 2, the sheet member moves between the lower surface of the guide wall 64 and the upper surface of the guide wall 66 of the lower housing 4. It is guided to the conveyance roller pair 44 through. Further, the illustrated automatic supply means 58 includes a cassette 70 in which the sheet members are loaded in a stacked state. The cassette 70 has a cassette receiving portion 74 defined at the bottom of the device body 2 through an opening formed on the left side of the device body 2.
It is detachably attached to. A feeding roller 76 is arranged above the cassette receiving portion 74. When the feeding roller 76 is rotated in the direction indicated by the arrow 78, the sheet member in the cassette 70 is fed by the action of the feeding roller 76, and the fed sheet member is guided by the guide wall 80 of the lower housing 4. It is guided to the pair of transport rollers 44 through the space between the guide portions 83 provided on the partition wall 82.

Further, the downstream end of the transport path is also branched into two, and in connection with this, the opening / closing part in the upper opening / closing housing 6
84 is selectively positioned at a first position shown by a two-dot chain line in FIG. 1 and a second position shown by a solid line in FIG. When the opening / closing portion 84 composed of the first member 86 and the second member 87 pivotally connected to the first member 86 is in the first position (at this time, the second member 87 is the first member). The sheet member sent from the first discharge roller pair 52 is directly discharged to the outside of the main body 2 of the apparatus and is held in the positional relationship of projecting from the member 86 of FIG. The upper surface) is accepted in the state. On the other hand, when the opening / closing portion 84 is in the second position (at this time, the second member 87
Is held in a positional relationship where it overlaps with the first member 86),
The sheet member delivered from the first discharge roller pair 52 is conveyed upward through the space between the opening / closing portion 84 and the upright wall portion 88 in the upper opening / closing housing 6, and by the action of the second discharge roller pair 90, the apparatus main body 2 It is discharged to the receiving portion 92 defined on the upper surface of the. The receiving portion 92 is defined by an inclined upper wall 94 of the upper opening / closing housing 6, and an upper end portion of the inclined upper wall 94 is rotatably supported between a receiving position shown in FIG. 1 and a storage position (not shown). It is attached to 96.

The operation of the above laser beam printer will be outlined below.

While the rotating drum 12 is rotated in the direction indicated by the arrow 14, the charging corona discharger 16 charges the photosensitive member of the rotating drum 12, and then the laser light from the laser light source (not shown) of the optical unit 24 is emitted. An electrostatic latent image corresponding to image information is formed on the surface of the photoconductor by being projected on the photoconductor.
Next, toner is applied to the electrostatic latent image on the photoconductor by the action of the developing device 18, and the electrostatic latent image is developed into a toner image. After that, the sheet member supplied from the manual feeding means 56 or the automatic feeding means 58 to the conveying path 54 is brought into contact with the photoconductor, and the toner image on the photoconductor is formed on the sheet member by the action of the transfer corona discharger 20. Transcribed. The sheet member on which the toner image is transferred is peeled off from the rotary drum 12 and then conveyed to the fixing roller pair 50, and the toner image is fixed on the surface of the sheet member by the action of the fixing roller pair 50. The sheet member on which the toner image is fixed is conveyed to the first discharge roller pair 52, and when the opening / closing portion 84 is at the first position, the sheet member is directly discharged onto the opening / closing portion 84. When the sheet member is discharged onto the opening / closing portion 84, as understood from FIG. 1, the sheet member is discharged with the surface on which the image is formed facing up. On the other hand, when the opening / closing part 84 is in the second position, the first
The sheet member conveyed to the pair of discharge rollers 52 is further conveyed to the upper side and then discharged to the receiving portion 92 by the action of the second pair of discharge rollers 90. When the sheet member is discharged onto the receiving portion 92, as will be understood from FIG. 1, the sheet member is discharged with the surface on which the image is formed facing down, and therefore, the page alignment of the sheet member thus discharged is performed later. No need to do. on the other hand,
The rotary drum 12 continues to rotate further, and the cleaning device 22 acts to remove the residual toner from the surface of the photosensitive member.

Support Structure of Rotating Drum Next, the support structure of the rotating drum 12 will be described with reference to FIG. 1 and FIGS. 2 and 3.

The unit frame 10 shown in the drawing is a pair of end walls arranged at intervals in a direction perpendicular to the paper surface in FIG. 1 (only one of them is shown in FIG. 1, and omitted in FIGS. 2 and 3). The rotary drum 12, the developing device 18, and the cleaning device 22 are mounted between the pair of end walls.

The rotary drum 12 is provided with a hollow cylindrical drum main body 104 made of, for example, an aluminum alloy, and a photoconductor is arranged on the peripheral surface of the drum main body 104. A large gear 106, which also functions as a driven gear, is formed on one end of the drum body 104. Circular end plates 108 (only one of which is shown in FIG. 1) are provided on both end surfaces of the drum body 104,
A short shaft 110 functioning as a shaft is provided at the center of the end plate 108.
a and 110b are fixed (in FIGS. 2 and 3, a short shaft 11 provided on one end plate not shown).
0a, and in FIG. 1, a minor axis 110b provided on the other end plate 108 is shown).

The shaft portion of the rotary drum 12, that is, the short shafts 110a and 110b, is provided on the substrate 102 of the lower housing 4 and is detachably and rotatably supported by the receiving means. One receiving means for supporting the short shaft 110a existing at one end of the rotary drum 12 is composed of the receiving member 112 shown in FIGS. 2 and 3. The receiving member 112 includes a body portion 116 and a body portion 11 in which a substantially U-shaped recess 114 is formed.
6 has a mounting wall portion 118 provided at one end of the mounting wall portion 118.
Are attached to the inner surface of the substrate 102 of the lower housing 4 by the attachment screws 120. In the specific example, the recess 114 has a body 116.
Extends downward from the upper surface of the base plate, and the bottom surface of the substantially semicircular shape defines a receiving surface 144a that supports the short shaft 110a. Further in connection with this receiving surface, it is configured as follows. Referring also to FIG. 5-A and FIG. 5-B, one end of the receiving surface 114a defined by the receiving member 112, that is, one end of the supporting surface in contact with the peripheral surface of the short shaft 110a (see FIGS. 2 and 5). -The left end in FIGS. 5A and 5B) extends slightly above the horizontal line H passing through the center of the short shaft 110a in a state where the short shaft 110a is supported by the receiving surface 114a, and thus One end of the surface 114a contacts and supports a part of the upper portion of the short shaft 110a. Further, at the other end of the receiving surface 114a (the right end in FIGS. 2, 5A, and 5B), in order to facilitate mounting and dismounting of the rotary drum 12 to and from the lower housing. An escape recess 114b is provided. This escape recess 114b is a recess in a specific example.
It is formed by gradually decreasing the curvature of the inner surface defining 114 toward the opening side. Instead of changing the curvature as described above, the escape recess 114bb may be formed by forming a notch or the like, for example.

Further, the other receiving means for supporting the short shaft 110b existing at the other end of the rotary drum 12 is composed of the receiving member 122 shown in FIG. The receiving member 122 also has a main body 126 and a main body 126 in which a substantially U-shaped recess 124 extending downward from the upper surface is formed.
Has a mounting wall portion (not shown) provided at one end thereof, and the mounting wall portion is mounted to the inner surface of the lower housing 4 of the substrate (not shown) by mounting screws or the like. The bottom surface of the concave portion 124 formed in the receiving member 122 defines a substantially semicircular receiving surface that supports the short shaft 110b, but the shape of the receiving surface is somewhat different from the shape of the receiving surface 114a of the receiving member 112. . That is, FIG. 1 and FIG.
As will be easily understood by comparing FIG. A and FIG. 5-B, the receiving surface of the receiving member 122 has a substantially semicircular shape with an open upper side, and the minor axis 110b is formed at both ends of the receiving surface. When supported by the receiving surface, it substantially coincides with a horizontal line (not shown) passing through the center of the short shaft 110b, and thus the receiving surface contacts and supports the lower peripheral surface of the short shaft 110b.

In the specific example, the rotary drum 12 is grounded to the apparatus main body 2 via the receiving members 112 and 122, and in this connection, the following configuration is provided. Rotating drum 12
In the above, the end plates at both ends of the drum body 104 and the short shafts 110a and 110b provided on these end plates are made of a metal material such as steel. The pair of substrates 102 of the lower housing 4 are made of iron, and the receiving members 112 and 122 are made of a copper-based sintered alloy. Therefore, the rotating drum
When the lower housing 4 is mounted on the lower housing 4 as required, the short shafts 110a and 110b present at both ends thereof are supported by the receiving members 112 and 122, and rotate via the contact portions between the short shafts 110a and 110b and the receiving members 112 and 122. The drum 12 is electrically grounded to the lower housing 4. And in such a state, the unit frame
When 10 is attached to the device body 2 as required, the rotating drum 12
Is electrically grounded to the mounting body 2. In the specific example, in order to ensure the ground between the rotary drum and the lower housing 4, one of the receiving members 112 is provided with a pressing member 128. The pressing member 128 can be formed of a conductive material such as phosphor bronze and, as shown in FIG.
It is attached to the attachment wall 118 at 0. This pressing member
One end of 128 is recessed through an opening formed in the main body 116.
It projects into 114 and acts on the end surface of the short shaft 110 a supported by the receiving member 112. The pressing member 128 elastically biases the short shaft 110a to the right in FIG.
The short surface of 0a is in contact with the pressing member 128, the other end surface of the short shaft 110b is in contact with the inner surface of the mounting member (not shown) of the receiving member 122, and the rotary drum is also through the end surfaces of the short shafts 110a and 110b. 12 is electrically grounded to the lower housing 4.

In the specific example, the receiving means is composed of the receiving members 112 and 122 mounted on the substrate 102 of the lower housing 4, but instead of this, both or one of the receiving means is formed in the end wall 102. (The receiving surface of the receiving recess may be substantially the same as the receiving surface defined by the receiving members 112 and / or 122).

Drive System of Rotating Drum Next, the drive system of the rotating drum 12 will be described mainly with reference to FIG. In FIG. 1, the apparatus main body 2 shown in FIG.
Is an auxiliary substrate 1 provided on the substrate 102 of the lower housing 4.
The auxiliary substrate 130 is provided with a drive system on the apparatus main body side. The drive system shown in FIG. 4 is equipped with an electric motor 132 that constitutes a drive source and is capable of forward and reverse rotations. The output shaft of this electric motor 132 serves as a gear 134 (see also FIG. 2) that functions as a drive connecting gear. Drive-coupled. That is, the output gear 136 fixed to the output shaft of the electric motor 132 meshes with the large gear 140 of the gear member 138, the small gear 142 of this gear member 138 meshes with the large gear 146 of the gear member 144, and the gear member 144 small gears 148 mesh with the gear 134. On the process unit 8 side, a large gear provided at one end of the rotary drum 12
The gear 106 is meshed with a gear 150 provided in the developing device 18, and the gear 150 is further meshed with a gear 152. The gear 150 is for rotating the sleeve of the magnetic brush mechanism 154 arranged in the developing housing 153 of the developing device 18,
Further, the gear 152 is for rotating the stirring member 156 for stirring the developer in the developing housing 153.
(See also FIG. 1) The large gear 106 is further meshed with a gear 160 via a gear 158 provided in the cleaning device 22. The gear 160 is a transfer member for transferring the toner collected in the toner collection chamber of the cleaning device 22 as required.
It is for rotating 162 (see also FIG. 1).
In the specific example, as will be easily understood, when the rotary drum 12 is mounted on the unit frame 10 as required, the large gear 106 of the rotary drum 12 is drivingly connected to the gear 150 of the developing device 18 and the gear 158 of the cleaning device 22. It And thus the rotating drum 12
When the unit frame 10 mounted with is mounted on the apparatus main body 2, the gear 106 of the rotary drum 12 is drivingly connected to the gear 134 on the apparatus main body 2 side.

In the specific example, when the electric motor 132 rotates normally, the output gear 136
Is rotated in the direction indicated by the solid line arrow, whereby the gear members 138 and 144, the gear 134 and the large gear 106 are also rotated in the direction indicated by the solid line arrow, and thus the rotary drum 12 is indicated by the arrow 14 (FIG. 1). Is rotated in the direction. Meanwhile, the electric motor 132
When the rotation is reversed, the output gear 136 is rotated in the direction indicated by the broken line arrow, whereby the gear members 138 and 144, the gear 134 and the large gear 106 are also rotated in the direction indicated by the broken line arrow, and thus the rotary drum 12 is indicated by the arrow 14. It is rotated in the direction opposite to the direction shown.

In the specific example, since the support structure for the rotary drum 12 described above is adopted, the following features are provided in relation to the drive system.

Mainly referring to FIG. 5-A, the large gear 106 of the rotary drum 12 and the gear 134 on the apparatus main body 2 side mesh with each other as shown in FIG. 4 (FIGS. 5-A and 5-B), that is, the large gear. In the case where the axis P connecting the center of rotation of 106 and the center of rotation of the gear 134 is tilted in the counterclockwise direction in FIG. 4 and FIG. First, when the electric motor 132 rotates in the normal direction, the transmission power F transmitted to the rotating drum 12 is in the direction shown by the solid arrow in FIG. 5-A. More specifically, the acting direction of the power transmission F is generally the gear wheel 106.
From the axis P connecting the center of rotation of the gear 134 to the center of rotation of the gear 134, that is, the rotation direction of the gear 134 about the center of rotation of the large gear 106, that is, 90 degrees clockwise when the electric motor 132 rotates in the forward direction and the pressure of the large gear 106. When the large gear 106 having a pressure angle of 20 degrees is used as in the specific example, the direction is the angle (90 + γ) rotated by adding the angle α, that is, in the direction indicated by the solid arrow in FIG. From axis H upward in the clockwise direction in FIG. 5-A.
It turns 14 degrees. On the other hand, a receiving member in a specific example
One end of the receiving surface 114a of the 112 extends from the horizontal axis H upward in the clockwise direction in FIG. 5-A to an angular position of substantially 60 degrees, and the other end of the receiving surface extends from the one end to the 5-A side. In the figure, it extends counterclockwise downward to an angular position of substantially 180 degrees. As described above, the transmission power F transmitted to the large gear 106 acts on the short shaft 110a as an acting force F ',
Due to the acting force F ′, the short shaft 110 a causes the receiving surface 1 of the receiving member 112.
The short shaft 110a and the receiving surface 114a are constantly kept in contact with each other by being biased in the direction of biting into the 14a, and thus the rotary drum 12 is reliably held in a predetermined positional relationship. Further, the receiving surface having a sufficient width in the acting direction of the power transmission F.
Due to the presence of 114a, the short shaft 110a can be reliably supported. To ensure the support of the short shaft 110a, the fifth
It is important to extend one end of the receiving surface 114a beyond the direction of action of the electric force F in a further clockwise direction, as can be easily understood from FIG.

On the other hand, when the electric motor 132 rotates in the reverse direction as described later, the electric force F transmitted to the rotary drum 12 becomes in the direction shown by the solid arrow in FIG. 5-B. More specifically, the direction of action of the electric force F is the direction of rotation of the gear 134 about the rotation center of the large gear 106 from the axis P, that is, 90 degrees in the counterclockwise direction when the electric motor 132 rotates in the reverse direction and the large gear 106. (90 + γ), which is the direction in which the pressure angle α is added, and in the specific example, it is counterclockwise in FIG. 5-B from the horizontal axis H.
It will be rotated 26 degrees. On the other hand, a receiving member in a specific example
The other end of the receiving surface 114a of 112 exists only up to an angular position that is rotated substantially 60 degrees downward in the counterclockwise direction from the horizontal axis H in FIG. 5-B. Is provided. As you can see, the rotating drum 12
When is rotated in the direction opposite to the direction indicated by arrow 14,
The electric force F transmitted to the large gear 106 acts on the short shaft 110a as an acting force F ′, and the acting force F ′ biases the short shaft 110a from the receiving surface 114a of the receiving member 112 toward the escape recess 114b. As a result, the minor axis 110a is somewhat moved to the escape recess 114b as shown by the chain double-dashed line in FIG.
The 110a can be easily separated from the receiving member 112.

Since the transmission force transmitted from the gear 134 to the large gear 106 mainly acts on one end of the rotary drum 12, one of the short shafts
It may be constructed as described above in relation to the receiving member 112 supporting 110a.

Control when stopping the electric motor In the laser beam printer described above, the electric motor
When the rotation of 132 is stopped, it is controlled as follows. In FIG. 6 showing a part of the control system of the laser beam printer, the illustrated laser beam printer includes a control means 164 which can be composed of, for example, a microprocessor. On the other hand, the image formation end signal generated at the end of the image forming process is sent to the control means 164. In addition, the jam signal generated by the jam detection switch 166 (the conveyance path 54
Is generated when a jam occurs at the safety switch 168 disposed in association with the upper opening / closing housing 6.
The housing open signal generated by is also sent to the control means 164. In the specific example, the image formation end signal, the jam signal and the housing open signal function as a motor stop signal for stopping the rotation of the electric motor 132, and when any of these is generated, the rotation of the electric motor 132 will be performed as described later. Be stopped. The electric motor 132 may be stopped by one or two of these signals or a signal other than these signals. The illustrated control means 164 includes a first timer 170 that elapses a first predetermined time and a second timer 172 that measures a second predetermined time. Such control means generates a motor forward rotation signal and a motor reverse rotation signal as described later, and when the forward rotation signal thus generated is sent to the electric motor 132, the electric motor 132 is rotated in the forward direction, and a reverse rotation signal is sent to the electric motor. When the electric motor 132 is fed, the electric motor 132 is reversed.

Next, referring mainly to FIG. 7, the control means 164
The control by will be described.

In the control of the specific example, first, in step n-1, it is determined whether or not the motor stop signal is generated. Then, when the motor stop signal is not generated, the process moves to the image forming routine and the predetermined image forming process is performed. On the other hand, when any one of the image formation end signal, the jam signal, and the housing open signal is generated, the process proceeds from step n-1 to step n-2. In step m-2, it is determined whether or not the second timer 172 has timed up. If not, then in step n-3, it is determined whether or not the first timer 170 has timed up. To be judged. At the time when any one of the image formation completion signal, the jam signal, and the housing open signal is generated, the first timer 170 and the second timer 172 are not set yet, and therefore, from step n-1. The process moves to step n-4 through step n-2 and step n-3. In step n-4, it is judged whether or not the motor reverse rotation signal is generated, and since the reverse point signal is not generated at the time when any of the above signals is generated, the steps from step n-4 to step n-4 are performed. Move to n-5.
At step n-5, the motor normal rotation signal generated by the control means 164 disappears, and then at step n-6, the control means 164 generates one of the image formation end signal, jam signal and housing open signal. A motor reverse rotation signal is generated based on the generated signal. This motor reverse rotation signal is supplied to the electric motor 132 when the first timer 170 times out, as will be described later. Next, at step n-7, the first timer 170 is set and the time counting of the first timer 170 is started. Then, in step n-8, the normal rotation of the electric motor 132 is stopped.

After step n-8, the process returns to step n-1 again, and passes through steps n-1 to n-3 and then to step n-
Go to 4. When the process proceeds to step n-4 again, since the motor reverse rotation signal is generated at step n-6, the process directly returns from step n-4 to step n-1. Then, the above-described operation is repeatedly performed until the first timer 170 counts the first predetermined time. The first timer 17
The first predetermined time, which is 0, is the time required for the electric motor 132 to completely stop its rotation after being deenergized, and may be, for example, about 50 msec.

When the first timer 170 measures the first predetermined time, the process moves from step n-3 to step n-9, and the control means 164
The reverse rotation signal generated at is sent to the electric motor 132,
The electric motor 132 is rotated in the reverse direction. Then, step n-10
At, the first timer 170 is cleared, and then at step n-11, the second timer 170 is set. When step n-11 is completed, the process returns to step n-1 again and the second
Steps n-1 to n-4 are repeated until the timer 172 counts the second predetermined time and the time is up, and the electric motor 132 continues to rotate in the reverse direction. During the second predetermined time counted by the second timer 172, the meshing state between the large gear 106 of the rotary drum 12 and the gear 134 on the apparatus main body 2 side is substantially released (in other words, the gear 134 is the gear 134). And big gear
The amount of backlash between the rotary drum 12 and
Is the time required to slightly rotate in the direction opposite to the direction indicated by the arrow 14, and is, for example, about 50 msec similar to the first predetermined time.
The degree is enough.

When the second timer 172 measures the second predetermined time, the process moves from step n-2 to step n-12, and the control means 164
The supply of the motor reverse rotation signal from is stopped, which stops the reverse rotation of the electric motor 132. Next, at step n-13, the second timer 172 is cleared, at step n-14 the motor stop signal is disappeared, and thereafter at step n-15, the motor reverse rotation generated by the control means 164 is reversed. The signal is also lost.

As described above, when the motor stop signal is generated and the electric motor 132 is deenergized, the electric motor 132 is
Is rotated in a direction opposite to the rotation direction at the time of image formation for a second predetermined time period counted by the second timer 172. Therefore, during image formation, the large gear 106 of the rotary drum 12 and the gear 134 on the apparatus body 2 side are rotated by the forward rotation of the electric motor 132.
Is in a sufficiently meshed state, but the electric motor 132 is slightly rotated in the reverse direction so that the meshed state of the large gear 106 and the gear 134 is substantially released, or both gears are weakly meshed. The short shaft 110 of the rotary drum 12 moves to the escape recess 114b defined in the receiving member 112. Thus, the rotating drum
When the unit frame 10 having the 12 mounted thereon is detached from the apparatus main body 2, it can be easily detached. Further, when the short shaft 110a of the rotary drum 12 is moved to the escape recess 114b of the receiving member 112, the rotary drum 12 can be easily detached from the unit frame 10.

Although a specific example of the image forming apparatus according to the present invention has been described above, the present invention is not limited to this specific example, and various modifications and corrections can be made without departing from the scope of the present invention.

For example, in the illustrated specific example, the rotary drum is attached to the unit frame, and the unit frame is attached to the apparatus main body, but the rotary drum is not limited to this. The same can be applied to the case of being directly removably attached to the. In this case, when the rotary drum is mounted on the apparatus main body, the large gear as the driven gear provided on the rotary drum is drivingly connected to the gear as the drive connecting gear provided on the apparatus main body.

<Effects of the Invention> The image forming apparatus according to the present invention is configured as described above, and the receiving means for instructing the shaft portion on the driven gear side provided at one end of the rotary drum is a part of the upper portion of the shaft Defining a substantially semi-circular receiving surface that covers the driving gear, and the power transmitted from the driving connecting gear to the driven gear when the driving connecting gear and the driven gear are drivingly connected to each other by the receiving surface of the receiving means. Since it is configured to be supported, the power transmitted from the drive connecting gear to the driven gear is reliably instructed to the receiving surface via the shaft portion.
Further, the upward tendency of the shaft portion due to the power transmitted from the drive connecting gear to the driven gear is reliably prevented by the upper surface of the receiving means, so that the shaft portion of the rotating drum is set at a predetermined position. It can be held securely.

According to the image forming apparatus of the present invention, the receiving means for supporting the shaft portion on the driven gear side provided at one end of the rotary drum has a substantially semicircular shape that covers a part of the upper portion of the upper shaft portion. After the drive surface of the drive source has been stopped and the drive source has been stopped, the drive source can be rotated somewhat in the direction opposite to the rotation direction during image formation. The disengaged state between the drive connecting gear and the driven gear is released by this, which facilitates the release of the connection between the drive connecting gear and the driven gear, and the rotary drum from the main body of the apparatus or the unit frame with the rotary drum mounted It can be easily removed from the main body.

[Brief description of drawings]

FIG. 1 is a simplified sectional view showing a specific example of a laser beam printer as an example of an image forming apparatus according to the present invention. FIG. 2 is a partially exploded perspective view for explaining the support structure of the rotary drum in the laser beam printer of FIG. FIG. 3 is a cross-sectional view showing a support structure of one end of the rotary drum. FIG. 4 is a diagram schematically showing a part of a drive system in the laser beam printer of FIG. FIGS. 5-A and 5-B show the action direction of the electric force when the electric motor normally rotates in the laser beam printer of FIG. 1 and the action direction of the electric force when the electric motor reversely rotates. The figure for explaining each. FIG. 6 is a schematic diagram showing a part of a control system in the laser beam printer of FIG. FIG. 7 is a flow chart showing control when stopping the electric motor in the laser beam printer of FIG. 2 ... Device body 8 ... Process unit 10 ... Unit frame 12 ... Rotating drum 18 ... Developing device 22 ... Cleaning device 106 ... Large gears (driven gears) 110a and 110b ... Short shaft (shaft part) ) 112 ... Receiving member (receiving means) 114a ... Receiving surface 114b ... Relief recess 122 ... Receiving member (receiving means) 132 ... Electric motor (drive system) 134 ... Gear (drive connecting gear) 164. Control means

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Claims (6)

(57) [Claims] 1. A rotary drum having a photoconductor on its surface,
A shaft portion provided at one end portion of the rotating drum is detachably and rotatably supported by a receiving means provided in the apparatus main body,
By mounting the rotary drum on the apparatus main body, an image formation in which a driven gear provided at one end of the rotary drum is drive-connected to a drive connecting gear provided on the apparatus main body and drive-connected to a drive source. In the apparatus, the receiving means for supporting the shaft portion provided at one end of the rotary drum defines a substantially semicircular receiving surface that covers a part of an upper portion of the shaft portion, and the drive coupling gear And the power transmitted from the drive connecting gear to the driven gear during drive connection of the driven gear is configured to be substantially supported by the receiving surface of the receiving means. Image forming apparatus. 2. An apparatus main body and a processing unit detachably mounted on the apparatus main body, the processing unit including a rotary drum rotatably mounted on a unit frame. A photoconductor is disposed on the surface, a driven gear and a shaft portion are provided at one end of the rotary drum, and a drive coupling gear drivingly coupled to a drive source and the rotary drum are provided in the main body of the apparatus. And a receiving means for supporting the shaft portion of the device. When the process unit is mounted at a predetermined position of the apparatus main body, the shaft portion is driven and connected to the driven gear. In the image forming apparatus supported by the receiving means, the receiving means defines a substantially semicircular receiving surface that covers a part of an upper portion of the shaft portion, and the drive connecting gear and the driven gear are drive-connected. The power transmitted from the drive connecting gear to the driven gear at times is And is configured to be supported by the receiving surface quality on receiving means, the image forming apparatus characterized by. 3. A rotary drum having a photoconductor on its surface,
A shaft portion provided at one end portion of the rotating drum is detachably and rotatably supported by a receiving means provided in the apparatus main body,
By mounting the rotary drum on the apparatus main body, a driven gear provided at one end of the rotary drum is drive-connected to a drive connecting gear provided on the apparatus main body and drive-connected to a drive source, thereby forming an image. In an image forming apparatus in which the rotary drum is sometimes rotated in a predetermined direction by the action of the drive source, the receiving means defines a substantially semicircular receiving surface that covers a part of an upper portion of the shaft portion, An image forming apparatus, characterized in that, after stopping the drive of the power source in the predetermined direction, the drive source is rotated somewhat in the opposite direction. 4. The receiving means for supporting the shaft portion of the rotary drum defines a substantially semi-circular receiving surface, one end portion of the receiving surface extending to an upper portion of the shaft portion, and the receiving portion. An escape portion is provided at the other end of the surface, and when the rotary drum is rotated in the predetermined direction, the shaft portion of the receiving means is driven by the power transmitted from the drive coupling gear to the driven gear. When the rotary drum rotates in the direction opposite to the predetermined direction while being biased in the direction of biting into the receiving surface, the shaft portion is moved from the receiving surface by the transmission power transmitted from the drive connecting gear to the driven gear. The image forming apparatus according to claim 3, wherein the image forming apparatus is biased in a direction toward the escape portion. 5. A rotary drum which is composed of a main body of the apparatus and a process unit detachably mounted on the main body of the apparatus, and is rotatably mounted on the frame of the process unit, and the surface of the rotary drum is provided. Is provided with a photosensitive member, a driven gear and a shaft portion are provided at one end of the rotary drum, and a drive coupling gear drivingly coupled to a drive source and the rotary drum Receiving means for supporting the shaft portion is provided, and when the processor unit is mounted at a predetermined position of the apparatus main body, it is drivingly connected to the driven gear and the shaft portion receives the receiving portion. In the image forming apparatus supported by the means, the receiving means defines a substantially semicircular receiving surface that covers a part of an upper portion of the shaft portion, and stops driving of the drive source in the predetermined direction. After that, the drive source is slightly rotated in the opposite direction. Forming apparatus. 6. The receiving means for supporting the shaft portion of the rotary drum defines a substantially semicircular receiving surface, one end of the receiving surface extending to an upper portion of the shaft portion, and the receiving portion. An escape portion is provided at the other end of the surface, and when the rotary drum is rotated in the predetermined direction, the shaft portion of the receiving means is driven by the power transmitted from the drive coupling gear to the driven gear. When the rotary drum rotates in the direction opposite to the predetermined direction while being biased in the direction of biting into the receiving surface, the shaft portion is moved from the receiving surface by the transmission power transmitted from the drive connecting gear to the driven gear. The image forming apparatus according to claim 5, wherein the image forming apparatus is biased in a direction toward the escape portion.