JP4117817B2 - Color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus using a two-component developer, and more particularly to improvement of developer supply means and developer recovery means.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, dry type developing devices widely used in color image forming apparatuses such as copying machines and printers use a two-component developer composed of toner and a carrier as a powder developer, and a developing roller is used for development. The developer is rotated and conveyed while carrying the developer thereon, and the electrostatic latent image formed on the latent image carrier is visualized by the developer. In such an image forming apparatus, in order to meet the demand for downsizing of the apparatus, the distances between the units are arranged close to each other.
[0003]
[Problems to be solved by the invention]
For this reason, the temperature in the image forming apparatus main body rises when the image forming apparatus is in operation or during standby, and the temperature of the toner in the developing apparatus rises. When the temperature of the toner rises, the charge amount (Q / M) of the toner itself is lowered, resulting in deterioration of image quality such as background stains. Therefore, we want to suppress the temperature rise of the developer in the developing device as much as possible. Further, when such a developer is used, the carrier deteriorates with time, so that the entire developer needs to be replaced with a new one as necessary.
[0004]
Therefore, in order to maintain the initial image quality, it is required to consume the toner as soon as possible and replace it with a new toner. However, if the amount of toner in the developing device is small, the toner is frequently replaced.
[0005]
This replacement temporarily stops the operation of the image forming apparatus, so that the operation time is interrupted. Therefore, the number of replacements should be as small as possible. Therefore, it is sufficient that the amount of the developer can be increased in the developing unit. However, the cleaning unit, the charging unit, Other units such as a transfer unit also exist, and if the developing device itself is enlarged, the entire image forming apparatus is increased in size and complexity.
[0006]
In addition, since the color image forming apparatus has a plurality of developing devices, depending on the arrangement (those close to or far from the heat source), there is a difference in temperature in each developing device.
[0007]
Accordingly, a first object of the present invention is to provide a temperature sensor separately in each developing device, so that each developer can be supplied and recovered independently according to a temperature change in each developing device, An object of the present invention is to provide a color image forming apparatus capable of preventing image quality deterioration due to an increase.
[0008]
A second object of the present invention is to provide a color image that can bring the position of the developer replenishing tank to a position independent of the developing device main body, hold as much developer as possible, and improve maintainability. It is to provide a forming apparatus.
[0009]
A third object of the present invention is to provide a color image forming apparatus capable of making the developer concentration uniform.
[0010]
A fourth object of the present invention is to provide a color image forming apparatus which can be supplied without increasing the temperature during the transfer of the developer.
[0011]
[Means for Solving the Problems]
In order to achieve the first object, a color image forming apparatus according to the present invention comprises:
A latent image carrier for each color that creates an electrostatic latent image; and
A developing device for each color that forms a visible image on the latent image carrier by performing visible image processing on the latent electrostatic image formed on the latent image carrier for each color, and
A developer temperature sensor that is provided in each color developing device and detects the developer temperature therein;
Developer supply means for each color for sending the developer in the developer supply tank for each color toward the developing device for each color;
Each color developer collecting means for sending the developer of each color developing device toward the developer supply tank for each color;
The developer supplying means and the developer collecting means of the developing device for each color are controlled for each color according to the detected temperature of the developer temperature sensor for each color, and the detected temperature of the developer temperature sensor for each color is a predetermined temperature T1. When the above is reached, control means for driving the developer supplying means and developer collecting means for that color, and stopping the developer supplying means and developer collecting means for that color when the temperature falls below a predetermined temperature T2 .
It is provided with.
[0013]
In order to achieve the second object, each developing device includes a developer carrying member that carries a developer containing toner and a carrier and conveys the developer to a developing region facing the latent image carrying member, and a width of the developer carrying member. Transverse agitating means for conveying the developer from one end to the other end in the direction and conveying the developer from the other end to the one end, and conveying means for conveying the developer in each developing device toward the developer collecting means for each color And.
[0014]
In order to achieve the third object, each developer supply tank includes an agitation transfer means for agitating the stored developer. The agitation transfer means of each developer supply tank is independently controlled and driven.
[0015]
To achieve the fourth object, the developer supplying means and developer recovering means, a state of the gas transfer means for moving the developer in each axial direction, is diffused developer is moved by the gas transfer means And a pipe for connecting the developing device and the developer supply tank via the gas transfer means .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a color image forming apparatus according to the present invention.
[0017]
The color image forming apparatus 0 includes a reading mechanism 8 including a light source, a reflecting mirror, and an imaging lens for exposing a document placed on a document placing table CG for use as a copying machine. According to the image, the laser of the writing unit 9 is irradiated to the photosensitive members 1BL, 1Y, 1M, and 1C, which are latent image carriers of black, yellow, magenta, and cyan, and writing is performed to create an electrostatic latent image. .
[0018]
Each photoreceptor 1BL, 1Y, 1M, electrostatic latent images formed on the 1C, each color developing devices 2 BL, 2Y, 2M, is processed visible image by 2C, the recording material comes fed from the sheet feeding device 11 The toner image is electrostatically transferred to P by a transfer belt 10a and transfer devices 10BL, 10Y, 10M, and 10C for each color. The transferred recording material is separated from each photoconductor by separation chargers 10bBL, 10bY, 10bM, and 10bC for each color, fixed by the fixing unit 13, and discharged from the paper discharge unit 14.
[0019]
Further, after the transfer, a cleaning device 15 that removes toner remaining on the transfer belt 10a and cleaning devices 12BL, 12Y, 12M, and 12C that remove residual toner on the surface of the photoreceptor of each color are provided.
[0020]
The developer supply device 3 includes a developer supply tank 3aBL, 3aY, 3aM, 3aC for each color, a common waste toner container 3e, a toner container 3dBL for each color, 3dY, 3dM, 3dC, a gas transfer unit 4, and a gas transfer unit. It comprises gas supply means 6 for supplying a gas for fluidizing the developer transferred by means 4, and each color developing device 2BL, 2Y, 2M, 2C and each color developer supply tank 3aBL, 3aY, 3aM, 3aC. The developer supplying means for feeding each color toward the developing devices 2BL, 2Y, 2M, and 2C for each color , and the developing devices 2BL, 2Y, 2M, and 2C for each color are supplied to the developer supplying tank 3aBL for each color. , 3aY, 3aM, are connected through the respective colors of developer collecting hand stage for feeding toward the 3aC, also toner recovery unit 17 and the color of the cleaning device 12B , 12Y, doing 12M, are connected to 12C, the recovery and the supply of the developer through these.
[0021]
The gas transfer means 4 includes powder pumps 4aBL, 4aY, 4aM, and 4aC for each color that transfer black, yellow, magenta, and cyan developers. On the other hand, the developer in the developer supply tanks 3aBL, 3aY, 3aM, and 3aC for each color is used as a mixture with the air supplied from the gas pumps 6aBL, 6aY, 6aM, and 6aC for each color of the gas supply means 6. each color developer supplying pipe 5aBL supply hand stage, 5aY, 5aM, conveys through the 5ac.
[0022]
2, 3 and 4 representatively show one developing device (black) 2BL, but the developing devices 2Y, 2M and 2C of other colors have the same structure.
[0023]
A developing roller 2a with a built-in magnet as a developer carrying member is disposed so that a part is exposed from the opening of the developing device 2BL facing the photosensitive member. When the developing roller 2a is regarded as a clock in FIG. 2, the magnet is a developing main pole P1 in a direction facing the photoconductor at about 7 o'clock, and a developer in directions at about 6 o'clock and 4 o'clock, respectively. Magnetic poles P2 and P3 for conveyance, magnetic poles P4 and P5 for delivering developer to the first conveyance roller 2b in directions of approximately 2 o'clock and 1 o'clock (the magnetic pole P5 can be omitted), and a developing doctor 2s at approximately 10 o'clock Magnetic poles P6 for regulating the developer are formed in opposite directions. The magnetic properties of each magnetic pole are, for example, that P1 is N, P2 is S, P3 is N, P4 is S, P5 is N, and P6 is S.
[0024]
Then, a bowl-shaped agent receiving case that is above the developing roller 2a, has no magnet magnetic pole in the developing roller 2a, and opens upward as an agent receiving member in a direction range in which the magnetic force is much smaller than the other directions. 2d is arranged. The agent receiving case 2d has a length in a direction penetrating the paper surface (axial direction of the photosensitive member) in FIG. Is slightly shifted in the direction from 11 o'clock to 12 o'clock of the developing roller 2a. A lateral agitation unit 20 as a lateral agitation means described later is provided inside the agent receiving case 2d.
[0025]
The lateral agitation unit 20 includes an outer agitation unit 2l and a helical screw that sends the developer from the back side (one end side) to the front side (the other end side) in the direction penetrating the paper surface in FIG. and 2m, conveying screw 2n cooperate in the direction of the central axis of the front side in the (other end side) that feed the developer to the back side (one end side) side.
[0026]
The horizontal stirring unit 20 is a dual mixer, and the outer screw paddle 2o is formed along a hollow cylindrical portion 2p, a stirring plate portion 2l parallel to a plurality of axes extending radially from the peripheral surface of the hollow cylindrical portion 2p, and the central axis direction. A spiral screw 2m that conveys the developer from the back side (one end side) toward the near side (the other end side), and the near side (the other end) along the central axis direction in the hollow cylindrical portion 2p. The inner screw 2n for conveying the developer from the back side to the back side (front side) is accommodated. An unillustrated agent intake port is formed at the front side (other end side) end of the hollow cylindrical portion 2p to allow the developer conveyed to the front side (other end side) end with the screw 2m to enter the hollow interior. At the back side (one end side) end, an agent discharge port (not shown) for discharging the developer conveyed to the back side (one end side) end by the inner screw 2n is formed.
[0027]
On the right side of the agent receiving case 2d, first to third conveying rollers 2b, 2e, and 2f that are conveying means are disposed along the right side wall of the case. With these, the developer is removed from the developing roller 2a, In addition, a pumping means for pumping the removed developer to the right end of the upper opening of the second developer receiving case 2g is configured.
[0028]
The first transport roller 2b faces the developing roller 2a from about 2 o'clock in the figure, the second transport roller 2e faces the first transport roller 2b, and the second transport roller 2e from above is Three transport rollers 2f face each other. The first to third transport rollers 2b, 2e, and 2f have the same structure as each other, and a non-rotatable magnet is provided therein so as to transport the developer on the side opposite to the agent receiving case 2d. Contained.
[0029]
On the left side of the agent receiving case 2d, there is a predetermined interval between the inner surface of the case 2h of the writing unit 1, and this interval portion overflows beyond the upper end of the left side wall of the agent receiving case 2d. This is a developer transport path 2i to the surface of the developing roller 2a. The inner surface of the unit case 2h located in the middle of the passage is an inclined surface 2h ′, and a temperature sensor 2k is provided on the inclined surface so that the detection surface 2j is substantially flush with the inclined surface. .
[0030]
In the above configuration, the developer carried on the developing roller 2a and passing through the facing portion of the photosensitive member is removed from the developing roller by almost 100% by the first conveying roller 2b and transferred to the second conveying roller 2e. Further, it is delivered to the third transport roller 2f and flows down into the second agent receiving case 2g over the right upper edge of the second agent receiving case 2g by centrifugal force or the like. The developer that has flowed down accumulates in the second agent receiving case 2g, and is sent from the back side (one end side) to the near side (the other end side) of the developing device 2 by a lateral conveying screw 2q having a length in the central axis direction. . As shown in FIG. 3, the developer sent to the near side (the other end side) falls and is stored in a pipe 2r having a length in the vertical direction that opens below the second agent receiving case 2g. The lower end of the pipe 2r is connected to the side of the horizontal conveying screw in a continuous manner.
[0031]
FIG. 3 shows the relationship between the lateral stirring unit 20 and the powder pump unit (gas transfer means) 4 of the developer recovery means . One end of the shaft of the lateral conveying screw 40a1 protrudes outside the case via a bearing and a shaft seal, and a gear G1 is fixed to the protruding portion. The gear G1 meshes with the gear G2, and the gear G2 is connected to the motor 40a6. The motor 40a6 gives a driving force to the lateral conveying screw 40a1. The developer stored in the pipe 2r is transferred to the powder pump main body 40a7 by its own weight and the lateral conveying screw 40a1.
[0032]
As the powder pump main body 40a7, a screw pump commonly called a MONO pump is used. This pump includes a rotor 40a2 connected via a drive motor 40a6 and a lateral conveying screw 40a1, a fixed stator 40a3 that is made of an elastic body such as a rubber material and surrounds the rotor 40a2, and holds the stator 40a3. Holder 40a4 and the like.
[0033]
There is a gap of about 1 mm between the side surface of the stator 40a3 and the inner wall surface of the holder 40a4, and communicates with the developer passage 40a8. An air supply port 40a9 is provided so as to blow air as a conveying gas from the gap into the developer passage. The air supply port 40a9 communicates with the developer passage 40a8, and the outside communicates with a pipe 6b provided in the air pump (gas pump) 6aBL. When the air pump 6aBL is activated, air is blown into the developer through the air supply port 40a9. As a result, fluidization of the developer coming out of the pump is promoted, and the developer transfer by the powder pump becomes more reliable. The toner that has passed through the powder pump body 40a10 passes through the developer recovery pipe 16 and is sent to the developer supply tank 3aBL. As the developer recovery pipe 16, it is very effective to use a material that is flexible and excellent in toner resistance.
[0034]
5, 6, and 7, the developer supply tank 3 a BL is provided along the axis extending from the powder pump 4 a BL of the developer supply means to the transport screw 4 a 1 that transfers the developer toward the developing device at the bottom. It has a screw spiral blade. By the operation of the powder pump 4aBL, the developer is sent out toward the developing device 2BL via the flexible pipe 4a7.
[0035]
Inside the developer supply tank 3aBL, above the conveying screw 4a1, at least one, usually a plurality of stirring and conveying means 3b1, 3b2, 3b3 (in this case, three) (three in this case) are spaced vertically. It is arranged.
[0036]
The lowermost agitation transfer means 3b1 is driven by a motor M1 via a gear G7 that meshes with the gear G3 and a gear G7 that is integral with the agitation transfer means 3b1 that meshes with the intermediate gear G6. The middle agitation transfer means 3b2 and the uppermost agitation transfer means 3b3 are driven by motors M2 and M3, respectively. In addition, it is also possible to drive arbitrary stirring transfer means by a single drive means through a gear mechanism with a clutch.
[0037]
The uppermost agitation transfer means 3b3 is replenished as necessary from the developer transferred from the developing device via the flexible pipe 16aBL, the developer in the developer supply tank 3aBL, and further from the attached toner container 3dBL. The toner density of the developer is made uniform by stirring the toner. The agitating / transporting means 3b1, 3b2, 3b3 and the conveying screw 4a1 are rotationally driven in the opposite directions in the width direction of the developer supply tank 3aBL as indicated by arrows D, E, F, and G in FIG.
[0038]
As a result, deviation of the developer in one direction can be prevented, toner density unevenness can be avoided, and early density uniformization can be realized.
[0039]
In addition, toner concentration sensors 3c1, 3c2, 3c3 are provided in the vicinity of the agitation transfer means 3b1, 3b2, 3b3, respectively. When the toner concentration in the developer supply tank 3aBL falls below a certain value by the toner concentration sensors 3c1, 3c2, and 3c3, the toner is supplied from the toner container 3dBL, and is stirred and transported. The toner density sensors 3c1, 3c2, 3c3 detect the toner density based on the change in the magnetic permeability of the developer. The toner density values detected by the toner density sensors 3c1, 3c2, and 3c3 are compared with a reference value, and when the toner density falls below a certain value and the toner becomes insufficient, the toner is supplied in a size corresponding to the shortage. A signal is output to a toner supply circuit (not shown).
[0040]
In FIG. 8, the developer temperature value detected by the temperature sensor 2k is input to the control means 18a composed of a CPU or the like. In the control means 18a, the detected temperature value of the developer is compared with a reference value set in a memory such as a RAM or a ROM, and the temperature has exceeded a certain value and the temperature of the developer has risen. In this case, a drive signal is output not only during the operation but also when the machine is stopped, and the developer supply means 18b for each color that sends the developer in the developer supply tank for each color toward the developing device for each color, and the development for each color. The developer collecting means 18c for each color that feeds the developer of the apparatus toward the developer supply tank for each color is driven simultaneously.
[0041]
Thus, the developer is recovered from the lateral stirring and conveying operation by the powder pump, and simultaneously the developer is supplied, and the process is repeated until the temperature in the developing device drops to a predetermined temperature.
[0042]
Next, temperature control will be described with reference to FIG.
In step S1, it is determined whether or not the developer temperature in the developing device detected by the temperature sensor 2k has reached a predetermined temperature T1. If the predetermined temperature has been reached, the process proceeds to step S2, and simultaneous driving of the developer supply means and the developer recovery means is started. As a result, the developer circulates through the developer supply tank 3aBL, and the temperature of the developer decreases.
[0043]
In step S3, it is determined whether or not the developer temperature has fallen below a predetermined temperature T2 (T1> T2). When it is determined that the temperature has fallen below the predetermined temperature T2, the process proceeds to step S4 , and the driving of the developer supply means and the developer recovery means is stopped.
[0044]
With the above configuration, each color is similarly configured.
Further, the toners collected by the respective color photoconductor cleaning devices 12BL, 12Y, 12M, and 12C are transferred to the toner containers 3dBL, 3dY, 3dM, and 3dC by the toner collecting means 17, respectively. At this time, a powder pump is used although not shown. The collected toner of each color is mixed with unused toner in each toner container and recycled.
In this way, the temperature of the developer in the developing device is prevented from increasing, and the image quality is stabilized.
[0045]
According to the color image forming apparatus of the first aspect, since the developer is supplied and recovered while monitoring the temperature in the developing device with the temperature sensor, it is possible to prevent the image quality from being lowered due to the temperature rise.
[0046]
According to the color image forming apparatus of the second aspect , the developer is conveyed from one end to the other end in the width direction of the developer carrier, and the developer is conveyed from the other end to the one end. Since the developer is transported toward the developer collecting means for each color, the developer supply tank can be moved to a position independent of the main body of the developing device, so that as much developer as possible can be retained and maintainability is maintained. Can be improved.
[0047]
According to the color image forming apparatus of the third aspect , since the developer supply tank has the stirring transfer means, the supplied toner and the collected developer are stirred together with the developer in the developer supply tank. Thus, a developer having a uniform density can be obtained.
[0048]
According to the color image forming apparatus of the fourth aspect , since the agitation transfer means is controlled for each developer supply tank, only the developer supply tank having an abnormal concentration can be agitated to obtain a uniform developer concentration. .
[0049]
According to the color image forming apparatus of the fifth aspect , since the developer is transferred together with the gas, the developer can be supplied without increasing the temperature during the transfer of the developer, so that the image quality can be prevented from being deteriorated.
[Brief description of the drawings]
1 is an overall schematic configuration diagram of a color image forming apparatus according to the present invention;
FIG. 2 is a cross-sectional view showing an internal structure of one developing device.
FIG. 3 is a cross-sectional view showing the relationship between the horizontal agitation unit and the powder pump unit (gas transfer means).
FIG. 4 is a perspective view of one developing device and a part of a developer supplying device that supplies a developer to the developing device.
FIG. 5 is a cross-sectional view of a developer supply device.
FIG. 6 is a sectional view taken along the line XX of the above.
FIG. 7 is a partial cross-sectional view of the developer supply device.
FIG. 8 is a block diagram of control means for controlling the developer supply means and the developer recovery means according to the temperature detected by the developer temperature sensor.
FIG. 9 is an operation flowchart of the control means.
[Explanation of symbols]
0 color image forming apparatus 1BL, 1Y, 1M, 1C photoconductor (latent image carrier)
2a Development roller (developer carrier)
2b, 2e, 2f Conveying roller (conveying means)
2BL, 2Y, 2M, 2C Developing device 2k Developer temperature sensor 2q Side feed screw 3 Developer supply device 3aBL, 3aY, 3aM, 3aC Developer supply tank
3b1 , 3b2, 3b3 Stirring transfer means 3dBL, 3dY, 3dM, 3dC Toner container 4 Gas transfer means 4a7 Flexible pipe 5aBL, 5aY, 5aM, 5aC Developer supply pipe 6 Gas supply means 6aBL, 6aY, 6aM, 6aC Gas pump
16 Developer recovery pipe 18a Control means 18b Developer supply means 18c Developer recovery means 20 Horizontal stirring unit (horizontal stirring means)
40a1 Horizontal transfer screw
P Recording material

Claims (5)

A latent image carrier for each color that creates an electrostatic latent image; and
A developing device for each color that forms a visible image on the latent image carrier by performing visible image processing on the latent electrostatic image formed on the latent image carrier for each color, and
A developer temperature sensor which is provided in the developing device for each color and detects the developer temperature therein;
Developer supply means for each color for sending the developer in the developer supply tank for each color toward the developing device for each color;
Developer collecting means for each color for sending the developer of each color developing device toward the developer supply tank for each color;
The developer supplying means and the developer collecting means of the developing device for each color are controlled for each color according to the detected temperature of the developer temperature sensor for each color, and the detected temperature of the developer temperature sensor for each color is a predetermined temperature T1. When the above is reached, control means for driving the developer supplying means and developer collecting means for that color, and stopping the developer supplying means and developer collecting means for that color when the temperature falls below a predetermined temperature T2 .
A color image forming apparatus comprising: Each developing device includes a developer carrying member that carries a developer containing toner and a carrier and conveys the developer to a developing region facing the latent image carrying member, and a developer from one end to the other end in the width direction of the developer carrying member. And a lateral agitation unit that conveys the developer from one end to the other, and a conveyance unit that conveys the developer in each developing device toward the developer collecting unit for each color. The color image forming apparatus according to claim 1 . Each developer supply tank, characterized in that it comprises the agitation transport means for stirring the developer reservoir, a color image forming apparatus according to claim 1 or 2,. Each agitating means for transferring the developer supply tank, and drives are controlled each independently, the color image forming apparatus according to claim 3. The developer supply means and the developer recovery means respectively supply a gas transfer means for moving the developer in the direction of the rotation axis, and a gas for flowing the developer moved by the gas transfer means in a diffused state. 5. The color image according to claim 2 , further comprising a gas supply unit and a pipe connecting the developing device and the developer supply tank through the gas transfer unit. Forming equipment.

Images