JP3869119B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that visualizes an electrostatic latent image using a developer.
[0002]
[Prior art]
In a dry type developing device widely used in image forming apparatuses such as copying machines and printers, a two-component developer composed of toner and carrier is used as a powder developer, and the developing roller is rotated during development. A developer is carried on the developing roller while being conveyed, and the electrostatic latent image previously formed on the latent image carrier is visualized by the developer.
[0003]
[Problems to be solved by the invention]
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. For this reason, the temperature in the apparatus rises when the image forming apparatus is in operation and during standby, The temperature of the toner will increase.
[0004]
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, there is a demand to suppress the temperature rise of the developer in the developing device as much as possible. Further, when such a two-component developer is used, the carrier deteriorates with time, so that the entire developer needs to be replaced with a new one as necessary.
[0005]
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. When the amount of toner in the developing device is small, the toner is frequently replaced.
[0006]
When the toner is replaced, the image forming apparatus must be temporarily stopped. Due to such a temporary stop, the operation of the image forming apparatus is interrupted and the operation time is limited. Therefore, it is better that the number of toner replacements is as small as possible. In order to reduce the number of replacements, it is sufficient that a large amount of developer can be put in the developing unit, but there are other units such as a cleaning unit, a charging unit, and a transfer unit in the image area around the photosensitive member. Therefore, the space cannot be ensured, and if the developing device itself is enlarged, the entire apparatus is increased in size and complexity.
[0007]
The present invention suppresses a developing device, the developer is circulated between the developer container separate from the developing device, size of the apparatus, the temperature rise of the developer without complicating by stirring An object of the present invention is to provide an image forming apparatus capable of avoiding uneven toner density .
[0008]
[Means for Solving the Problems]
In order to achieve the object, the present invention has the following configuration.
(1). A rectangular parallelepiped agent configured as a separate body from the developing device in an image forming apparatus including a developing device having a developer carrying member that carries the developer and conveys the developer to a developing area facing the latent image carrier A storage unit , a supply unit for supplying the developer in the agent storage unit to the developing device, a recovery unit for recovering the developer in the development device in the storage unit , and replenishing toner in the storage unit And a toner replenishing means, and a recovery pipe through which the developer recovered from the developing device is sent is communicated with the upper portion of the agent containing portion, and the developer is sent out from the lower portion of the agent containing portion to the developing device. A plurality of agitation transfer means arranged in the vertical direction with the shaft portion being laterally arranged in the agent storage portion between the communication portion of the recovery pipe in the storage portion and the transfer means are provided. Spaced apart vertically Are arranged, each of the agitating transfer means sends reversed developer together was being stirred. (Claim 1).
(2). In the image forming apparatus according to (1) , a toner concentration sensor is provided in the vicinity of the agitation transfer unit, and when the toner concentration in the agent container falls below a predetermined value by the toner concentration sensor, the agent toner was Rukoto is supplied to receptacle (claim 2).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
In the following example, a developer carrier that carries a developer including toner and a carrier and transports the developer to a development region facing the latent image carrier, and from one end side to the other end side in the width direction of the developer carrier. A lateral agitation means for conveying the developer and conveying the developer from the other end side to the one end side; and a developer carried on the developer carrying member and passing through the development region from the one end side to the other end. An image forming apparatus provided with a developing device having conveying means for conveying to the end side will be described.
[0015]
In FIG. 3, a copying machine 102 will be described as an image forming apparatus. A charging device 104, an exposure device 105, a developing device 106, a transfer belt 107, and a cleaning device 108 are arranged around a drum-shaped photoconductor 103 as an example of a latent image carrier along the rotation direction indicated by arrows. Has been placed.
[0016]
The exposure apparatus 105 includes an exposure optical mechanism 105B including a light source, a reflecting mirror, and an imaging lens for exposing a document placed on a document placement table 105A installed on the upper surface of the copying machine 102. A corresponding electrostatic latent image is formed on the photosensitive member 103.
[0017]
The electrostatic latent image formed on the photoconductor 103 is visualized by the developing device 106 and electrostatically transferred to the recording paper fed from the paper feeding device 109 by the transfer belt 107. The transferred recording sheet is fixed by the fixing device 110 and discharged. After the transfer, a cleaning unit (not shown) is provided to remove toner remaining on the transfer belt 107, and a cleaning device 108 is provided to remove residual toner on the photoconductor 103. . The paper feeding device 109 includes a plurality of paper feeding cassettes that can store recording papers of different sizes, and can feed paper of a selected size.
[0018]
The developing device 106 will be described with reference to FIGS. 4, 5, and 6.
A developing roller 2 with a built-in magnet as a developer carrying member is disposed so as to be partially exposed from an opening of a unit case 28 having a length in the axial direction of the photosensitive member 103.
[0019]
When the developing roller 2 is regarded as a clock in FIG. 4, the magnet provided on the developing roller 2 is the developing main pole P1 in the direction of about 7 o'clock facing the photoconductor 103, about 6 o'clock and 4 o'clock. Developer transfer magnetic poles P2 and P3 in the direction of 2 respectively, and developer delivery magnetic poles P4 and P5 to the first transport roller 21 in the directions of approximately 2 o'clock and 1 o'clock (the magnetic pole P5 can be omitted), Magnetic poles P6 for restricting the developer are respectively formed in the direction of about 10 o'clock facing the developing doctor 8.
[0020]
The magnetic properties of each magnetic pole are, for example, N for the developing main pole P1, S for the magnetic pole P2, N for the magnetic pole P3, S for the magnetic pole P4, N for the magnetic pole P5, and S for the magnetic pole P6.
[0021]
A hook-shaped agent receiving case 24 that is open above the developing roller 2 in a direction range in which there is no magnetic pole of the magnet in the developing roller 2 and the magnetic force is significantly smaller than the other directions is used as the agent receiving member. It is arranged. The agent receiving case 24 has a length in a direction penetrating the paper surface in FIG. 4 (axial direction of the photosensitive member), and a lowermost portion located at the center in the width direction of the developing roller 2 (substantially left-right direction in FIG. 4) The developing roller 2 is slightly deviated in the direction from 11:00 to 12:00.
[0022]
A horizontal stirring means is provided inside the agent receiving case 24. The lateral agitating means includes an outer agitating plate portion 26a for feeding the developer from the rear side (one end side) to the front side (the other end side) in the direction penetrating the paper surface in FIG. And the inner conveying screw 27 that feeds the developer from the near side (the other end side) to the far side (the one end side) in the central axis direction.
[0023]
This lateral stirring means is a dual mixer, and the outer screw paddle 25 has a hollow cylindrical portion 26, a stirring plate portion 26a parallel to a plurality of axes extending radially from the peripheral surface of the hollow cylindrical portion 26, and a central axis direction. And a spiral screw part 26b that conveys the developer from the far side (one end side) toward the near side (the other end side), and in the hollow cylindrical part 26, the near side along the central axis direction. The inner screw 27 for conveying the developer from the other end side to the inner side (one end side) is accommodated.
[0024]
An unillustrated agent intake port is formed at the front (other end) side end of the hollow cylindrical portion 26 to allow the developer conveyed to the front (other end) end by the screw portion 26b to enter the hollow interior. A developer discharge port (not shown) is formed at the rear (one end) end to discharge the developer conveyed to the rear (one end) end by the inner screw 27 to the outside.
[0025]
On the right side of the agent receiving case 24, a first transport roller 21, a second transport roller 22, and a third transport roller 23 are arranged in this order from the bottom along the right side wall of the case. The first transport roller 21, the second transport roller 22, and the third transport roller 23 have lengths in the central axis direction, and remove the developer carried on the photosensitive member 103 and passed through the development region from the development roller 2. And the conveyance means which pumps up the removed developer to the right end side of the upper opening of the second developer receiving case 50 is configured.
[0026]
In FIG. 4, the first transport roller 21 faces the developing roller 2 from the direction of approximately 2 o'clock, the second transport roller 22 faces the first transport roller 21, and the second transport roller 22 further The third conveyance roller 23 faces from above. The first to third transport rollers 21, 22, and 23 have the same structure as each other so that the developer is transported on the side opposite to the side on which the agent receiving case 24 is provided. Contains a non-rotatable magnet.
[0027]
On the left side of the agent receiving case 24, there is a space having a predetermined interval between the inner surface of the unit case 28, and this interval portion exceeds the upper end of the left side wall of the agent receiving case 24 and overflows the developer. A developer conveyance path 40 to the surface of the developing roller 2 is provided. The inner surface of the unit case 28 located in the middle of the developer transport path 40 is an inclined surface, and a temperature sensor 29 is provided on the inclined surface so that the detection surface 29a is substantially flush with the inclined surface. ing.
[0028]
In the above configuration, the developer carried on the developing roller 2 and passing through the opposing portion (developing area) of the photoconductor 103 is removed by the first conveying roller 21 from the developing roller 2 by almost 100 percent, and the second conveying roller. 22 and further transferred to the third conveying roller 23, and flows down into the second agent receiving case 50 over the right upper edge of the second agent receiving case 50 by centrifugal force or the like.
[0029]
The developer that has flowed down accumulates in the second agent receiving case 50 and is sent from the rear side (one end side) to the front side (the other end side) of the developing device 106 by a lateral conveying screw 51 having a length in the central axis direction. The developer sent to the near side (the other end side) is provided integrally with the developing device 106 and has a pipe 52 (see FIG. 5) having a length in the vertical direction that is open on the lower surface of the second agent receiving case 50. 5)) and collected. A lower end portion of the pipe 52 is connected to a portion of the lateral conveyance screw 54 in a communication manner. Here, the second agent receiving case 50 and the lateral conveying screw 51 are conveying means for conveying the developer carried on the photosensitive member 103 and passing through the developing region from the back side (one end side) to the near side (the other end side). Configure.
[0030]
One end of the shaft of the lateral conveying screw 54 protrudes out of the case through 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 a motor 56. Further, the other end side of the shaft of the lateral conveying screw 54 is connected to a screw pump. The motor 56 gives a driving force to the lateral conveying screw 54 and the screw pump 55. The developer accumulated in the pipe 52 is fed toward the screw pump 55 by its own weight and the rotation of the lateral conveying screw 54.
[0031]
As the screw pump 55, a powder pump commonly called a MONO pump is used. The screw pump 55 includes a rotor 58 connected via a drive motor 56 and a lateral conveying screw 54, a fixed stator 59 made of an elastic body such as a rubber material and surrounding the rotor 58, and A holder 60 for holding the stator 59 is provided.
[0032]
There is a gap of about 1 mm between the side surface of the stator 59 and the inner wall surface of the holder 60 and communicates with the developer outlet 61 that is the discharge port of the pump. An air supply port 62 is provided so as to blow into the developer outlet 61 from this gap. The air supply port 62 communicates with the developer outlet 61.
[0033]
In addition, as shown in FIG. 6, the air supply port 62 communicates with the air pump 63 via a pipe 65. When the air pump 63 is activated, air is blown into the developer through the air supply port 62. Thereby, fluidization of the developer discharged from the screw pump 55 is promoted, and the developer is more reliably transferred by the screw pump 55.
[0034]
Developer exit 61 is a discharge port of the screw pump 55 is communicated with the collection pipe 67 for collecting the developer, the recovery pipe 67 1, 7, and agent container 6 6 8 It communicates with the top of the. Agent container 6 6 and the developing device 106 is a rectangular parallelepiped container made separately, the image forming apparatus main body as shown in FIG. 3, i.e., from the site covered with the outer casing of the copying machine 102 In order not to be affected by the temperature of the outer casing, it is provided as a separate body adjacent to the outer case.
[0035]
With this configuration, the developer sent from the screw pump 55 is sent to the agent container 66 through the recovery pipe 67. For the recovery pipe 67, it is very effective to use a material that is flexible and excellent in toner resistance. By using a flexible pipe, there are less restrictions on the installation on the developing device 106 side and the agent container 66 side, the effective use of these installation locations is possible, and the maintenance workability is improved.
[0036]
7 and 8, a conveyance screw 69 for transferring the developer toward the developing device 106 is provided at the bottom of the agent container 66. The conveying screw 69 is provided with a spiral blade twisted along the axis.
[0037]
One end of the shaft of the conveying screw 69 is connected to a screw pump 75 having the same structure as the screw pump 55. The other end side of the shaft of the conveying screw 69 protrudes out of the container through a shaft sealing portion and a bearing, and a gear G3 is fixed to the protruding end.
[0038]
The gear G3 and the worm wheel G4 are integrally formed, and the worm wheel G4 is connected to the motor M1 through the worm G5, and constitutes a drive system for the conveying screw 69 and the screw pump 55. Air is supplied to the air supply port 76 of the screw pump 75 from the same air pump 80 (see FIG. 7) as the air pump 63.
[0039]
The discharge port (see FIG. 7) of the screw pump 75 is connected in communication with the developing device 106 (see FIG. 6) via a supply pipe 77. By actuation of conveyor screw 69 and screw pump 75 also causes the air pump 80, the developer in the developer container 66 is fed toward the developing device 106 through the supply pipe 77. The supply pipe 77 uses a flexible pipe for the same reason that the recovery pipe 67 is made flexible. As shown in FIG. 6, the supply pipe 77 is connected to the developing device 106 through an enlarged pipe 78 provided on the back side, and is fed from above the outer screw paddle 25 in FIG. 4.
[0040]
When the replenishment toner container 74 is provided inside the container 68 and above the conveying screw 69, at least one, usually a plurality of agitation transfer means, in this example, three agitation transfer means 71 are provided. , 72, 73 are arranged at intervals in the vertical direction.
[0041]
The lowermost agitation transfer means 71 is driven by a motor M1 via an intermediate gear G6 that meshes with the gear G3 and a gear G7 that is integral with the agitation transfer means 71 that meshes with the intermediate gear G6. The middle agitation transfer means 72 and the uppermost agitation transfer means 73 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. These agitating means 71, 72, 73 and the conveying screw 69 send the developer in the directions opposite to each other in the direction of the arrow, and transport and agitate the developer.
[0042]
As shown in FIG. 8, a replenishment toner container 74 for replenishing new toner is provided in the agent container 66 so as to communicate with the upper part of the agent container 66. A replenishing roller 79 that feeds toner by rotation is provided in the middle of a path that connects the replenishing toner container 74 and the agent container 66. By driving the supply roller 79 with a motor (not shown), new toner in the supply toner container 74 can be supplied to the agent container 66. At the top of the supply toner container 74 have lid 74 F is provided, it is possible to appropriately supply the toner by opening this lid 74 F.
[0043]
With this configuration, the uppermost agitation transfer means 73 can be supplied from the developer transferred from the developing device 106 via the recovery pipe 67, the developer in the toner container 66, and the supplied toner container 74 as necessary. The virgin toner to be replenished is agitated to make the developer toner concentration uniform.
[0044]
As described above, these agitating and transferring means 71, 72, 73 and the conveying screw 69 send the developer in the directions opposite to the arrows as shown in FIG. 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.
[0045]
Further, as shown in FIG. 8, toner density sensors 81, 82, and 83 are provided in the vicinity of the agitation transfer means 71, 72, and 73, respectively. When the toner density in the container 68 falls below a certain value by the toner density sensors 81, 82, 83, the toner is supplied from the toner container 74, and is stirred and transported. The toner concentration sensors 81, 82, and 83 detect the toner concentration based on a change in the magnetic permeability of the developer. The toner density values detected by the toner density sensors 81, 82, and 83 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 magnitude corresponding to the shortage. A signal is output to a toner supply circuit (not shown), and as described above, the supply roller 79 is operated to supply toner from the supply toner container 74 to the agent container 66.
[0046]
In the above configuration, the screw pump 75, the air pump 80 as the air supply means, the transport screw 69 as the feed means, the supply pipe 77, the agitation transfer means 71, 72, 73, etc. constitute the first transfer means. The transfer means constitutes agent supply means (indicated by reference numeral 71 in FIG. 1) for supplying the developer in the agent container 66 to the developing device 106.
[0047]
Similarly, the screw pump 55, the air pump 63 as the air supply means, the lateral conveyance screw 54 as the feeding means, the recovery pipe 67, the pipe 52, and the like constitute the second transfer means, and this second transfer means is the developing device 106. It constitutes the developer material collecting in the agent container 66 collecting means (indicated by reference numeral 7 2 in Figure 1).
[0048]
In FIG. 1, the detection information of the developer temperature of the developing device 106 by the temperature sensor 29 is input to the control means 73 configured by a CPU or the like. In the control means 73, the detected developer temperature value is compared with a reference value set in a memory such as RAM or ROM, and the temperature exceeds a certain value and the developer temperature is increased. In addition, a drive signal is output to the control circuit, and based on this drive signal, the agent supply means 71 and the agent recovery means 72 are simultaneously driven.
[0049]
Thereby, the recovery of the developer from the developing device 106 to the agent container 66 and the supply of the developer from the agent container 66 to the developing device 106 are performed in parallel, and the developer circulates. Here, since the agent container 66 is independently provided at a position not affected by the temperature from the copying machine 102, the developer is cooled in the circulation process. This circulation is continued until the temperature of the developer falls below a predetermined temperature.
[0050]
The temperature control process by the control means of FIG. 1 will be described with reference to FIG.
In step <1>, it is determined whether or not the developer temperature in the developing device detected by the temperature sensor 29 has reached a predetermined temperature T. If the predetermined temperature T has been reached, the process proceeds to step <2>, where simultaneous driving of the agent supply means and the agent recovery means is started. As a result, the developer circulates through the agent container 66, and the temperature of the developer decreases.
[0051]
In step <3>, it is determined whether or not the temperature of the developer has dropped below a predetermined temperature T ′ (where T> T ′). When it is determined that the temperature has fallen below the predetermined temperature T ′, the process proceeds to step <4>, and the driving of the agent supply unit and the agent recovery unit is stopped. Thereby, the temperature of the developer can be maintained in the range of about T to T ′.
[0052]
Such control can be performed not only while the copying machine 102 is in operation but also when the copying machine is stopped. In this way, the temperature of the developer in the developing device 106 can be prevented from increasing, and the image quality can be stabilized.
[0053]
In this example, since the replenishment toner container 74 is provided, the agitation transfer means 71, 72, 73 are also configured as a part of the first transfer means as the agent supply means, but the replenishment toner container 74 is provided. In some cases, stirring and circulation are sufficiently performed even if these stirring and transporting means are not provided.
[0054]
In the above example, the two-component developer is described as the developer. However, the present invention can also be applied to an image forming apparatus using a one-component developer.
[0055]
【The invention's effect】
According to the first aspect of the present invention, the developer is circulated between the developing device and the agent container that is separate from the developing device, and the temperature of the developer is increased without increasing the size and complexity of the device. The toner density unevenness can be avoided by stirring .
According to the second aspect of the present invention, the toner density level is maintained by supplying the toner.
[Brief description of the drawings]
FIG. 1 is a diagram showing a control circuit for performing developer temperature control according to the present invention.
FIG. 2 is a flowchart for performing developer temperature control according to the present invention.
FIG. 3 is a diagram for explaining the overall configuration of a copying machine as an example of an image forming apparatus suitable for carrying out the present invention.
FIG. 4 is a cross-sectional view of the developing device.
FIG. 5 is a cross-sectional view of main parts of a developing device and a second transfer unit.
FIG. 6 is a perspective view of main parts of a developing device and a second transfer unit.
FIG. 7 is a partial cross-sectional front view showing the main parts of the agent container and the first transfer means.
FIG. 8 is a partial cross-sectional side view showing the main parts of the agent container and the first transfer means.
[Explanation of symbols]
29 Temperature sensor 66 Agent container 71 Agent supply means 72 Agent recovery means 73 Control means

Claims (2)

In an image forming apparatus provided with a developing device having a developer carrying member that carries the developer and conveys the developer to a developing region facing the latent image carrying member,
A rectangular parallelepiped containing portion that is configured separately from the said developing device,
And supplying agent supply means to the developing device a developer of the developer container,
The developer and recovered to the powder recovery unit to the developer container of the developing device,
Toner replenishing means for replenishing toner into the agent container;
With
A recovery pipe through which the developer recovered from the developing device is sent is communicated with an upper portion of the agent containing portion, and a conveying means for sending the developer from the lower portion of the agent containing portion to the developing device is provided,
Between the communicating part of the recovery pipe in the storage part and the transport means, a plurality of agitation transfer means arranged vertically in the agent storage part with the shaft part being laterally arranged are spaced apart in the vertical direction. An image forming apparatus , wherein each of the agitation transfer units is configured to feed and stir the developer in opposite directions . 2. The image forming apparatus according to claim 1, wherein a toner concentration sensor is provided in the vicinity of the agitation transfer unit, and when the toner concentration in the agent container falls below a predetermined value by the toner concentration sensor, the agent image forming apparatus to which the toner in the accommodating section is characterized Rukoto supplemented.

Images