JP2008275752A - Color image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce cost, noise, size and weight in a color image forming apparatus using a rotary configuration by performing a plurality of drivings in a developing operation with one motor.
A plurality of drive trains are driven by a single motor.
[Selection] Figure 1

Description

  The present invention relates to a color image forming apparatus using a rotary structure in a color copying machine, a color printer, or the like using electrophotographic technology.

  Conventionally, a single pulse motor is used as a driving source for bringing the developing device held by the rotary unit into contact with or separated from the photosensitive member, and a rotary is used to move the developing device held by the rotary unit to a predetermined position. One DC motor and an encoder for detecting the rotational position are used as a driving source for rotation, and one motor is used for driving the developing roller of the developing device.

For example, Patent Document 1 and Patent Document 2 can be cited as conventional examples.
JP 2004-0379980 A JP 2002-014512 A

  In the conventional method, since three motors are used in the developing process, the cost becomes high. In addition, power consumption has increased and noise has increased.

  In order to solve the above-described problems, the present invention provides a motor capable of forward / reverse rotation, a cam mechanism that swings the rotary unit away from the photoreceptor, and pressurizes the rotary unit toward the photoreceptor. These operations were realized using a spring mechanism and a sensor for position detection.

  By rotating the rotary unit, driving the development roller, and driving the rotary photosensitive drum with a single motor that can rotate forward and backward, the motors used for each drive and its The encoder for rotational position detection can be omitted, and the cost can be reduced.

  In addition, by using a single motor and simplifying the mechanism, it is possible to reduce the size and weight.

  Next, the first embodiment of the rotary configuration and rotary drive in the present invention will be described.

  FIG. 1 shows a schematic configuration of a rotary portion according to the present invention.

  Reference numeral 101 denotes a driving device (motor) capable of forward and reverse rotation. The motor performs the first rotation and the second rotation in the direction opposite to the first rotation. 131 is a rotary unit. 110 is a gear attached to the motor 101. Reference numeral 115 denotes a shaft that is rotatably supported by the main body of the image forming apparatus and supports the rotary unit so as to be swingable. Reference numerals 102, 103, 105, 106, and 109 denote gears attached to the shaft 115. 104 and 108 are gears formed on the disk peripheral surfaces of the rotary left and right. At this time, the gears 104 and 108 formed on the disk peripheral surface have the same module and the same number of teeth.

  First, a mechanism for rotating the rotary will be described.

  The gear 102 and the gear 109 that transmit driving directly to the disk have the same module and the same number of teeth, and are supported by the shaft 115 so as to be rotatable only in one direction via a one-way. The gear 102 and the gear 109 are driven when the motor is rotated in the second direction, and the drive is transmitted to the gear 104 and the gear 108 on the circumferential surface of the disk. The side surface of the disk 104 has a protruding shape 104a to prevent the reverse rotation of the rotary, and the 104a portion is hooked by a ratchet 104b.

  When the motor is rotated in the first direction, the drive is not transmitted because the gear 102 and the gear 109 are connected via the one-way. Therefore, the drive is not transmitted to the gear 104 and the gear 108 on the disk peripheral surface on the rotary side. Further, since the ratchet 104b is hooked on the protrusion shape 104a, the rotary is stationary without rotating in the reverse direction.

  When the motor is rotated in the second direction, driving is transmitted to the gear 102 and the gear 109, the gear 104 and the gear 108 are rotated, and the rotary is rotated. At this time, the rotational position of the rotary is detected by 107 sensors (photo interrupters), and it is possible to know which developing unit of yellow, magenta, cyan, and black is in the developing position with respect to the photosensitive member.

  Next, a mechanism for bringing the rotary into contact with and separating from the photosensitive member will be described.

  A gear 105 shown in FIG. 2 is supported on a shaft 115 so as to be rotatable in one direction via a one-way, and transmits a drive to a separation cam 116 for swinging the rotary unit in a direction away from the photosensitive member. . The gear 105 transmits the drive only when the motor rotates in the first direction, and transmits the drive to the gear train that transmits the drive to the separation cam 116, so that the cam rotates.

  When the motor is rotated in the first direction, the drive is transmitted to the gear 105 and is transmitted to the gear 118. The drive of the gear 118 is decelerated via the gear 119 and then transmitted to the gear 117 coaxial with the separation cam 116, the cam starts to rotate slowly, and the rotary is pushed to the photosensitive member side by the pressure spring 113, It abuts on the photoreceptor at a predetermined pressure. The developing roller of the developing unit held by the rotary unit abuts on the photosensitive member during one development, and the developing unit is also photosensitive by being pushed back by the separation cam 116 in the direction away from the photosensitive member. Stop away from the body. At this time, the transition of the rotational position of the cam 116 when developing toners of four colors of yellow, magenta, cyan, and black is shown in FIG. The cam 116 opposes the springs 113 and 114 that pressurize the rotary in a direction approaching the photosensitive member when the rotary performs a swinging motion so that the rotary moves away from and contacts the photosensitive member. It plays the role of returning to the direction of leaving.

  When the motor is rotated in the second direction, the drive is not transmitted to the gear 105 and the cam 116 is not driven, so that the rotary unit is also stationary without swinging.

  Next, a mechanism for driving the developing roller will be described.

  A gear 103 shown in FIG. 3 is supported on the shaft 115 so as to be rotatable in one direction via a one-way, and transmits driving to the developing rollers of a plurality of developing cartridges held in the rotary. The gear 103 transmits driving when the motor rotates in the first direction, and transmits driving to a gear train that drives the developing roller on the developing cartridge side, so that the developing roller rotates.

  The rotary unit holds a developing cartridge of Y (yellow), M (magenta), C (cyan), and K (black) and swings around the shaft 115. Reference numerals 120, 121, 122, and 123 denote gears for driving the developing rollers in the developing cartridges of yellow, magenta, cyan, and black, and reference numerals 124, 125, 126, and 127 denote the developing rollers of the developing cartridges.

  When the motor is rotated in the first direction, the gear 103, which is a one-way gear, transmits driving to the gear 128 shown in FIG. The drive transmitted to the gear 128 is transmitted to the gear 122 fixed coaxially with the developing roller 126 via the gear 130 and the gear 129. At this time, the developing roller 126 in contact with the photosensitive member rotates to perform development. The gear 129 is on a straight line connecting the center of the rotary unit and the center of the developing roller driving gear during development, and the developing roller (124, 125, 126, 127) of each developing cartridge rotates to a position facing the photoconductor and stops. When this occurs, it engages with the developing roller drive gear (120, 121, 122, 123) to transmit the drive.

  When the motor is rotated in the second direction, the driving is not transmitted to the gear 103, and the driving is not transmitted to the gear train for driving the developing roller, so the developing roller does not rotate.

  Here, the gear 105 that transmits the drive to the cam 116 and the gear 103 that transmits the drive to the developing roller are one-way gears that transmit the drive in the reverse direction to the gear 102 and the gear 109 on the same axis (shaft 115). When rotating in the second direction, no drive is transmitted, the rotary is in a state of being separated from the photosensitive member, and the developing roller also does not rotate.

  A series of development operations are performed by the above drive mechanism.

  First, the motor is rotated in the second direction. The rotary starts rotating, and the Y developer unit is moved to the position facing the photoconductor among Y (yellow), M (magenta), C (cyan), and K (black) developer units held by the rotary. Move and stop.

  Next, the motor is rotated in the first direction. The drive is transmitted to the drive train of the cam mechanism and the drive train of the developing roller. The rotary mechanism swings in the direction approaching the photoconductor by the cam mechanism, and the Y developing device contacts the photoconductor. At the same time, the drive is transmitted to the developing roller, and the developing roller rotates to develop Y. At this time, the Y developing roller is in contact with the photosensitive member while developing for one color is performed, and the rotary is pushed back by the cam mechanism to move again to a position away from the photosensitive member. This completes the development for Y.

  Next, the motor is rotated again in the second direction. The rotary rotates, and this time the M (magenta) developer moves to a position facing the photoconductor and stops.

  When the motor is rotated in the first direction, as in the case of Y, the M developing device abuts on the photosensitive member and performs development. Then, the developing device is separated from the photosensitive member and stopped by the cam mechanism.

  Similarly, development is performed for C (cyan) and K (black), and development is performed in the order of Y → M → C → K, and the development operation for one image is completed.

  Next, a second embodiment will be described.

  Here, a description will be given of a case in which a link mechanism is used to swing the rotary unit in a direction away from the photosensitive member in order to separate the developing device from the photosensitive member during rotary rotation.

  As shown in FIG. 4, the drive from the gear 105 on the swing shaft is transmitted to the gear 137 fixed coaxially with the disk 138 through the gears 134, 135, 136. Further, a link 139 as shown in FIG. 4 is rotatably attached to the disk 138 at a position shifted from the center. The link 139 is attached so that the elongated groove 150 on the main body side 140 slides in the left-right direction at the same time. The elongated hole groove 150 is moved when the link slide portion 139a moves to the rightmost side (in FIG. 4). It has a shape with a clearance gap. The side plate of the rotary unit is pushed in a direction approaching the photosensitive member by a pressure spring 113.

  When the motor is rotated in the first direction, the drive is transmitted to the gear 105, and when the disk 138 rotates, the portion 139b attached to the disk of the link is pulled to the photoreceptor side, the link 139 is drawn to the photoreceptor side and the link When the slide part 139a hits the long hole ridge 150a of the main body 140, the rotary unit pushes the pressure spring 113 and is pulled toward the main body side. Thereby, the developing roller of the developing device held by the rotary unit is separated from the photosensitive member. When the disk continues to rotate, the portion 139b moves to the main body side 140, and the rotary unit is released from the restraint of the link by the escape portion of the slotted groove 150. The developing roller of the container contacts the photoconductor with a predetermined pressure.

  When the motor is rotated in the second direction, the drive is not transmitted to the gear 105, so the disk 137 does not rotate and the drive is not transmitted to the link mechanism. Therefore, the rotary unit is in a stationary state without performing a swinging motion.

  As described above, the operation performed by the cam mechanism is performed using the link mechanism, and the developing device held by the rotary is brought into contact with and separated from the photosensitive member to perform the developing operation for each of Y, M, C, and K colors. .

  FIG. 5 shows a drive train to which drive is transmitted when the motor is rotated in the first direction and when the motor is rotated in the second direction, and its role.

The perspective view showing the outline of the rotary unit concerning the present invention. FIG. 6 is a schematic diagram illustrating a drive train when the rotary unit is swung in a direction away from the photosensitive member. FIG. 5 is a schematic diagram illustrating a drive train when transmitting the driving of the developing roller. FIG. 3 is a schematic diagram illustrating a drive train when a rotary unit is swung in a direction away from a photoreceptor using a link device. The drive operation in the rotation direction of the motor. Schematic showing the rotational position of the cam when developing four colors of yellow, magenta, cyan and black on letter paper and B5 paper.

Explanation of symbols

101 Forward / reverse motor
102, 109 Gears that transmit drive when the motor is rotated in the second direction
103 Gear that transmits drive to the developing roller when the motor rotates in the first direction
104, 108 Gears formed on the disk circumference at both ends of the rotary
105 Gear that transmits drive to the cam 116 when the motor rotates in the first direction
107 Sensor for detecting the revolving position of a rotary (photo interrupter)
111, 112 Side plates on both sides that fix the central axis of the rotary unit with the shaft 115 as the center of oscillation
113, 114 Spring that presses part of the side plates 111 and 112 and pushes the rotary unit toward the photoconductor
115 A shaft that holds the gears 102, 103, 105, 106, 109, and is the center of oscillation of the rotary unit and the side plates 111, 112
116 Cam attached to the side plate to separate the rotary from the photoconductor
120, 121, 122, 123 Gears fixed coaxially with each developing roller
124, 125, 126, 127 Yellow, magenta, cyan, black development rollers
129 Gears that transmit drive to the development roller drive gear for each color
131 Rotary unit holding multiple developers
132 photoconductor
133 Intermediate transfer member
138 Disc with one end of link 139 attached
139 Link attached to disk 138 and image forming device 140
140 Image forming device body
150 Slotted groove formed in the image forming apparatus main body 140 so that the link 139 can slide

Claims (5)

A rotary unit that holds a plurality of developing units, each developing unit can be rotated to a position facing the photosensitive member, and can be swung around a swinging shaft;
One motor that can rotate forward and reverse,
A mechanism for pressurizing the rotary unit in a position where the selected developing device is opposed to the photoconductor toward the photoconductor;
In order to separate the developing unit from the photosensitive member, the rotary unit is configured to swing in a direction away from the photosensitive member.
When the motor rotates in the first direction, driving the developing roller for developing the photosensitive member, and driving the rotary to contact and separate from the photosensitive member, and rotating in the second direction, An image forming apparatus, wherein a rotary drive for moving a developing device to a predetermined position with respect to a photosensitive member is driven.   2. The image forming apparatus according to claim 1, wherein a cam is used to swing the rotary unit in a direction away from the photosensitive member.   The image forming apparatus according to claim 1, wherein a link mechanism is used to swing the rotary unit in a direction away from the photosensitive member. A rotary unit that holds a plurality of developing units, each developing unit can be rotated to a position facing the photosensitive member, and can be swung around a swinging shaft;
One motor that can rotate forward and reverse,
A gear through a one-way that conveys rotational drive in only one direction;
A cam or link mechanism for separating the rotary unit in a position where the selected developing device is opposed to the photoconductor from the photoconductor;
A spring mechanism for pressurizing the rotary unit in a direction approaching the photosensitive member to bring the developing device into contact with the photosensitive member. The second one-way is free, and when the motor rotates in the second direction, the second one-way is transmitted and the first one-way is free,
A gear for driving the developing roller and a gear for driving a separation cam for separating the rotary from the photosensitive member are provided on the downstream side of the drive train of the first one-way.
A gear for revolving the rotary is provided downstream of the second one-way drive train,
When the time from when the separation cam rotates until the developing roller comes into contact with the photosensitive member and when the developing roller separates is defined as t, this t becomes longer than the time for the developing roller to develop one page on the photosensitive member. Yes,
An image forming apparatus having the drive mechanism described above.   5. The image forming apparatus according to claim 4, wherein a link mechanism is used to swing the rotary unit in a direction away from the photosensitive member.

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