JPH04221980A - Developing device by toner - Google Patents

Abstract

PURPOSE:To prevent the deficit of the concentration of toner over all areas of a developing part even if the width of a recording sheet is enlarged and a pattern having a large amount of toner consumption is printed, on a device carrying out development with a tow-component system developer composed of the toner and a carrier. CONSTITUTION:In the device where a mixing room 6 in which the toner replenished to a developing device is stirred/mixed with the carrier, and a supplying room 4 in which a developer stirred/mixed in the mixing room 6 is supplied to the developing part, are disposed in parallel with a partition 5 interposed, and communicated on both ends of the partition, and which has a stirring/ carrying unit 7 stirring/mixing the toner newly replenished with the carrier and transfers it, in the mixing room 7, and a stirring/carrying unit 8 transferring the developer transferred from the mixing room 6 in the opposite direction of a developer flow in the mixing room 6, in the supplying room 4, a constitution is adopted so that the communicative path 12 of the supplying room 4 and the mixing room 6 is provided, besides both end parts of the partition 5.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] Electrophotographic recording units in laser printers, facsimile machines, copying machines, etc. are developed by attaching toner to an electrostatic latent image. The present invention relates to an apparatus for performing development using a two-component developer consisting of toner and carrier.

0002

[Prior Art] Fig. 6 shows a conventional developing device, (a)
is a plan view of the inside of the developing device, and (b) is a plan view of the inside of the developing device.
(b) is a sectional view, and (c) is a print density characteristic diagram. A two-component developer supply device 2 is disposed adjacent to the latent image forming drum 1, and a position 3 adjacent thereto serves as a developing section. A two-component developer supply chamber 4 is provided adjacent to the developer supply device 2, and a mixing chamber 6 is further provided with a partition wall 5 in between.

In the illustrated example, a magnetic roller is used as a developer supply device, and screws 7 and 8 are provided in the supply chamber 4 and the mixing chamber 6 to mix and transport the toner and carrier. is built-in. The partition wall 5 is not provided at both end positions, and the communication paths 9, 1
It is 0.

[0004] In this device, the developer is
The screws 7 and 8 rotate so as to circulate in the order of 2, a3, a4, and a1. That is, the screw 7 in the mixing chamber 6 is rotated clockwise by its blades so as to transfer the developer in the direction of the arrow a1, and the screw 8 in the supply chamber 4 is rotated to the right to transfer the developer in the direction of the arrow a3. is rotated to the left. The developer transferred in the direction of the arrow a1 by the screw 7 of the mixing chamber 6 reaches the end, is transferred to the supply chamber 4 through the communication path 9, and is transferred in the direction of the arrow a3 within the supply chamber 4. When reaching the end of the supply chamber 4, the communication passage 1
0 to the mixing chamber 6.

[0005] Therefore, the toner and carrier are stirred and mixed in the mixing chamber 6 by the rotation of the screw 7, and the toner is frictionally charged and attached to the carrier, and then the toner is transferred to the supply chamber 4.
When the toner is transferred, it is attracted by the adjacent magnet roller 2 in the supply chamber 4, and transported to the developing section 3, where only the toner is attracted to the latent image on the latent image forming drum 1, and development is performed. The carrier remaining after development is returned to the supply chamber 4 again.

As described above, after the toner is consumed in the developing section 3, only the carrier is returned to the supply chamber 4, so the amount of toner decreases toward the downstream side of the developer flow in the supply chamber 4, that is, closer to the communication path 10. do. Therefore, new toner is replenished by the toner replenishing section 11 near the communication path 10 where the amount of toner is least. Then, the two-component developer with the smallest amount of toner and new toner are mixed into the mixing chamber 6.
While moving in the direction of arrow a1, the toner is stirred and mixed uniformly so that the toner is triboelectrically charged.

[0007]

[Problems to be Solved by the Invention] Recently, as office automation equipment has become more widespread and its uses have expanded, paper sizes have increased.
Since the amount of toner is sufficient on the upstream side of the developer flow,
Sufficient print density can be obtained, but as the paper width increases,
On the downstream side, there is a shortage of toner, and a problem has arisen in that the print density drops below the tolerance level d.

[0008] Also, when printing a pattern that consumes a large amount of toner, such as graph printing or graphic printing, there is a shortage of toner on the downstream side of the developer flow, and the print density decreases.

[0009] Therefore, various improvements have been attempted to enable printing with uniform density over the entire range of the developing section 3, but none have been effective.

[0010] The technical problem of the present invention is to address such problems and to solve the problem of insufficient toner concentration in the entire developing area even when the width of recording paper is expanded or when printing a pattern that consumes a large amount of toner. The goal is to prevent this from happening.

[0011]

[Means for Solving the Problems] (1) A mixing chamber 6 in which the toner supplied to the developing device is stirred and mixed with the carrier, and a two-component developer mixed in the mixing chamber 6 is mixed in the entire area of the developing section 3. A supply chamber 4 for supplying water is arranged in parallel with a partition wall 5 in between. In a normal developing device, the two chambers 4 and 6 communicate with each other through communication passages 9 and 10 at both ends of the partition wall 5, but in the present invention, a communication passage 12 is also provided at the middle part, other than at both ends. ing.

The mixing chamber 6 has an agitation conveyor 7 that transfers the newly supplied toner and carrier from one end to the other while stirring and mixing.
The mixing chamber 6 includes an agitating conveyor 8 that conveys the two-component developer transferred from the mixing chamber 6 in a direction opposite to the developer flow in the mixing chamber 6.

(2) In the mixing chamber 6, the toner is supplied so that new toner is replenished near the confluence of the developer in the mixing chamber 6 and the developer that has flowed in from the intermediate communication path 12. It has a supply section 13.

(3) In the supply chamber 4, a toner concentration detector S2 is disposed near a position where the developer is diverted to the intermediate communication path 12, and a detection signal from the detector S2 is used to detect the toner concentration. The toner replenishment amount in the toner replenishment section 13 is configured to be controlled.

(4) A guide for guiding the flow of developer between the supply chamber 4 and the mixing chamber 6 is fixed or semi-fixed in the intermediate communication path 12.

(5) A rotator for forcibly exchanging the developer between the supply chamber 4 and the mixing chamber 6 is disposed in the intermediate communication path 12 .

[0017]

[Function] (1) Since the agitating conveyor 7 of the mixing chamber 6 and the agitating conveyor 8 of the supply chamber 4 operate to convey the developer in the directions of arrows a1 and a3, respectively, the toner replenishing section 1
The two-component developer in which the toner and carrier replenished in step 1 are stirred and mixed in the mixing chamber 6 is conveyed toward the communication path 9 at the other end, but a portion is transferred from the intermediate communication path 12 to the supply chamber 4 side. The toner flows into the supply chamber 4, replacing the developer whose toner has been consumed, and is transported in the direction of arrow a3.

In this way, a new two-component developer flows in from the middle, replaces the developer that has consumed toner, and is transferred to the developing section via the developer supply device 2 while moving in the direction of arrow a3. Served. In this way, new developer replaces the developer that has consumed toner,
(b) As shown in the figure, it is possible to prevent the toner density in the printed area from increasing and dropping below the allowable density.

Further, the developer that has consumed toner while reaching the communication path 12 in the supply chamber 4 flows into the mixing chamber 6 and merges with the developer in the mixing chamber 6, and is transferred to the most upstream side of the supply chamber 4. Therefore, the problem that the print density is too dark only on the upstream side of the supply chamber 4 is also solved.

(2) The toner replenishing section 11 is provided in the communicating path 10 at the end where the developer returns after the toner has been consumed, as in the prior art, but in the present invention, In addition, a toner replenishing section 13 is also provided at the confluence section with the developer flowing in from the intermediate communicating path 12.

As described above, if the developer having consumed toner flows in from the intermediate communicating path 12, the concentration of the developer supplied from the communicating path 9 to the upstream side of the supply chamber 4 is optimal. There is no problem, but if the density is insufficient, even if the developer whose toner has been consumed in the supply chamber 4 flows into the mixing chamber 6 from the communication path 12, new toner is replenished in the toner supply section 13, so that the end It is possible to prevent the toner concentration of the developer supplied from the communication path 9 to the supply chamber 4 from decreasing.

(3) The toner concentration before the developer in the supply chamber 4 flows into the mixing chamber 6 from the intermediate communication path 12 is detected by the toner concentration detector S2, and based on the detection signal, the toner supply section 13 is detected. Since the amount of toner replenishment in is controlled, the toner concentration of the developer supplied from the communication path 9 at the end to the supply chamber 4 is optimized.

(4) A guide for guiding the flow of the developer between the supply chamber 4 and the mixing chamber 6 is disposed in the intermediate communication path 12, so that the developer flow from the supply chamber 4 to the mixing chamber 6 is provided. The flow of the developer from the mixing chamber 6 to the supply chamber 4 becomes smooth, and as a result, insufficient print density can be more reliably prevented.

The guide may be fixed after setting its angle, or may be semi-fixed so that the angle can be adjusted.

Furthermore, as described in claim 5, by providing a rotator in place of the fixed or semi-fixed flow guide, the developer in the intermediate communicating path 12 can be forcibly replaced. , insufficient print density can be more reliably prevented.

[0026]

EXAMPLES Next, examples will be used to explain how the toner-based developing device of the present invention is actually implemented. Figure 2,
FIG. 3 shows an embodiment of a developing device using toner of the present invention, and FIG.
is a partial cross-sectional/plan view of the inside of the developing device, and FIG. 3 is II of FIG.
It is a sectional view taken along I-III (with a cover attached). Stirring conveyor 7 in the mixing chamber 6 and stirring conveyor 8 in the supply chamber 4
are both made of screws. Both ends of the partition wall 5 are connected through communication passages 9 and 10 as in the conventional case, but
They also communicate through an intermediate communication path 12 according to the invention. In this embodiment, there is only one communication path other than both ends of the partition wall 5, but there may be communication at a plurality of locations. In addition, G1
, G2 is a drive gear for the screws 7 and 8, and G3 is a drive gear for the magnet roller 2.

Reference numeral S1 denotes a toner concentration detector that has been conventionally installed, and is disposed at the downstream end of the developer flow in the supply chamber 4. S2 is a toner concentration detector according to the present invention, and is disposed at the bottom of the supply chamber 4 near the part where the developer is diverted to the intermediate communication path 12.

If there are multiple communication paths other than both ends of the partition wall 5, a toner concentration detector is provided corresponding to each communication path.

In this embodiment, the toner replenishing section is omitted, but as shown in FIGS. 4 and 5, a toner replenishing section is provided on the communication path 10 at the end corresponding to the toner concentration detector S1. 11 is disposed in the mixing chamber 6, and a toner replenishing section 13 is disposed in the mixing chamber 6 at a confluence with the developer flowing in from the communication path 12. The toner replenishing units 11 and 13 are controlled according to detection signals from the toner concentration detectors S1 and S2, so that the optimum toner concentration is always maintained.

4 and 5 show examples of a developer replacement controller provided in the intermediate communication path 12. FIG. 4 shows an example in which the control is performed using the flow of developer, and FIG. 5 shows an example in which the controller is controlled by using an external drive. This is an example of forcibly controlling the flow. In FIG. 4, the structure is such that a guide plate 14 is erected in the communication path 12,
The optimum angle between the guide plate 14 and the partition wall 5 is selected and fixed. In the supply chamber 4, part of the developer flowing from the upstream side hits the guide plate 14 as shown by arrow a6 and is guided to the mixing chamber 6 side, and the developer flowing from the upstream side in the mixing chamber 6 is removed. and is conveyed to the communication path 9 side at the end.

Further, in the mixing chamber 6, a part of the developer flowing from the upstream side hits the guide plate 14 as shown by arrow a5 and is guided to the supply chamber 4 side, and flows inside the supply chamber 4 from the upstream side. It merges with the incoming developer and is supplied to the developing section while moving toward the communicating path 10 at the end.

FIG. 5 shows an impeller 15 provided in the communication path 12,
Its central vertical axis is connected to an external drive source such as a motor. Since the impeller 15 is rotated clockwise in the figure, a part of the developer flowing from the upstream side in the supply chamber 4 is transferred to the impeller 15 as shown by arrow a6.
The developer is sent to the mixing chamber 6 side, joins with the developer that has flowed from the upstream side in the mixing chamber 6, and is supplied to the developing section while moving to the communicating path 9 side at the end.

In addition, in the mixing chamber 6, a part of the developer flowing from the upstream side is sent to the supply chamber 4 side by the impeller 15 as indicated by arrow a5, and flows through the supply chamber 4 from the upstream side. It merges with the developer that has arrived and is conveyed to the communicating path 10 side at the end.

Note that a rotator such as the impeller 15 may be mounted horizontally and rotated about a horizontal axis.

As described above, the movement of the developer from the supply chamber 4 to the mixing chamber 6 and from the mixing chamber 6 to the supply chamber 4 is performed by utilizing the natural flow of the developer by the agitation conveyor. However, as shown in FIGS. 4 and 5, it is also possible to use a fixed or semi-fixed guide plate 14, or an externally driven rotating blade 15.

[0036]

Effects of the Invention As described above, according to the present invention, the supply chamber 4
A communication path 12 is provided in the partition wall 5 between the mixing chamber 6 and the mixing chamber 6 at other ends as well, and the flow of the developer is used or the guide plate 14 or the externally driven impeller 15 is used to forcibly
In the middle of supply chamber 4 and mixing chamber 6, part of the developer in both chambers 4 and 6 is exchanged. In this way, the developer that has consumed toner is replaced with a new developer containing enough toner in the middle of the supply chamber 4, thereby preventing the print density from decreasing on the downstream side of the supply chamber 4. can.

[Brief explanation of the drawing]

FIG. 1 is a plan view and a print density characteristic diagram illustrating the basic principle of a developing device using toner of the present invention.

FIG. 2 is a partial cross-sectional and plan view showing the entire example.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a plan view of an example in which a guide plate is used as a developer replacement controller.

FIG. 5 is a plan view of an example in which a rotating blade is used as a developer replacement controller.

FIG. 6 is a plan view, a sectional view, and a print density characteristic diagram showing a conventional toner-based developing device.

[Explanation of symbols]

1 Latent image forming drum 2 Developer supply device (magnetic roller) 3 Developing section 4 Supply chamber 5 Partition wall 6 Mixing chambers 7, 8 (agitation conveyor) screws 9, 10 Communication passages 11, 13 at both ends Toner supply section S1 , S2 Toner concentration detector 12 Intermediate communication path (communication path other than both ends of the partition wall)
14 Guide plate 15 Impeller

Claims (5)

[Claims] 1. A developing device that agitates and mixes toner and carrier and supplies the mixture to a developing section, comprising: a mixing chamber (6) for agitating and mixing the toner supplied to the developing device with the carrier; ) is a supply chamber (4) that supplies the two-component developer stirred and mixed to the entire area of the developing section, and a partition wall (5).
), and the two chambers communicate with each other at both ends of the partition wall, and the newly supplied toner and carrier are mixed and stirred in the mixing chamber (6) while being mixed from one end to the other. The two-component developer transferred from the mixing chamber (6) is transferred to the supply chamber (4) in a direction opposite to the developer flow in the mixing chamber (6). In a device having an agitation conveyor (8) that transfers the material in the same direction, the supply chamber (4)
A developing device using toner, characterized in that a communication path (12) is provided between the mixing chamber (6) and the mixing chamber (6). 2. In the mixing chamber (6), new toner is replenished near the confluence of the developer in the mixing chamber (6) and the developer flowing from the intermediate communication path (12). 2. The toner-based developing device according to claim 1, further comprising a toner replenishing section (13) so as to provide a toner replenishing section. 3. In the supply chamber (4), a toner concentration detector (S2) is disposed near a position where the developer is diverted to the intermediate communication path (12), 3. The toner developing device according to claim 2, wherein the amount of toner replenishment in said toner replenishing section (13) is controlled by the detection signal of said toner replenishing section (13). 4. A guide for guiding the flow of developer between the supply chamber (4) and the mixing chamber (6) is provided in the intermediate communication path (12) in a fixed or semi-fixed manner. 4. The toner-based developing device according to claim 1, 2 or 3. 5. A rotating device for forcibly replacing the developer between the supply chamber (4) and the mixing chamber (6) is disposed in the intermediate communication path (12). 4. A developing device using toner according to claim 1, 2 or 3.