JP3354388B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer replenishing device used in a developing device of an electrophotographic image forming apparatus, and more particularly to a toner replenishing device in a developing device using a dry developer.
The present invention relates to a highly-reliable developing device that prevents problems such as image blurring caused by deterioration in fluidity.

[0002]

2. Description of the Related Art As is well known, in an image forming section of an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, etc., an electrostatic latent image formed on a photoreceptor is transferred to a toner from a developing device. , And the developed image is transferred onto a transfer sheet and fixed to form an image. The developing device is provided with a developing frame, and a developing roller is exposed from an opening provided at a position where the developing frame faces the photoreceptor. The operation of supplying the toner in the agent onto the photoreceptor is performed. A toner replenishing tank as a developer replenishing device is detachably connected to the toner hopper portion of the developing frame, and replenishment of the developer from the toner replenishing tank into the developing frame is performed. FIGS. 6A and 6B are main part configuration diagrams of an example of a developing device in a conventional electrophotographic image forming apparatus, in which a developer replenishing device for replenishing a dry developer in a developing device main body is shown. Is shown.

The developing device communicates with a developing roller 2 disposed in a developing frame 1 and facing a photoreceptor (not shown) and a replenishing port 3 located diagonally above the developing roller 2 (above the toner hopper 1A). And a developer replenishing device (toner replenishing tank) 4 connected detachably. A supply roller (magnet roller) 5 is disposed at a position directly above the supply port 3 with a predetermined gap therebetween so as to be rotatable in the direction of the arrow.
A scraper 6 having a projection shape is provided at a position facing the outer peripheral surface of the supply roller 5, and the scraper 6 has a predetermined gap between the scraper 6 and the peripheral surface of the supply roller 5. An agitator 7 is disposed inside the toner supply tank 4 so as to be rotatable in the direction of the arrow. The developer T at the bottom of the supply device is scraped in the direction of the supply roller indicated by the arrow A in cooperation with the thin film 8 at the tip thereof. increase. The scraped-up developer T is taken up by the supply roller 5 which is driven to rotate in the direction of the arrow, guided to the supply port 3, and supplied into the developing frame 1.

In this conventional example, by providing the scraper 6 as the ear cutting means, it is possible to prevent the developer from leaking from the replenishing port 3 when the toner replenishing tank 4 is replaced, and to rely only on the rotation of the agitator 7. Variations in the amount of toner supplied to the developing frame 1 and deterioration in image quality due to the variation can be prevented. By the way, in this conventional example, while the developing device main body is operating, the replenishing roller 5 continuously rotates only in a certain direction,
The developer on the outer periphery of the replenishing roller scraped by the scraper 6 is constantly fed into the hopper 1A during the operation of the developing device main body.
When the inside of the hopper 1A is full, the developer which cannot move is forced to get over the scraper 6 and return to the toner supply tank 4. However, in the above-described conventional developing device, the density of the developer in the hopper 1A becomes very high when the developer in the toner supply tank 4 cannot move into the hopper 1A, so that the flow of the developer And the smoothness of toner supply to the developing means (specifically, the developing roller 2) is hindered. As a result, image quality defects such as image blurring due to an insufficient supply amount occur. It was easy (Fig. 6 (b)).

Conventionally, a powerful stirring means has been provided in the hopper in order to physically break the developer having reduced fluidity in the hopper and to enhance the fluidity. Also, the effect on image blurring was not perfect, and as a side effect, other problems such as the developer spouting out of the developing device from the connection between the toner replenishing tank and the hopper and soiling the inside of the image forming device main body were observed. I could be invited. The present invention provides a toner which is a disadvantage of the above prior art.
Prevents deterioration of fluidity, eliminates image blurring,
It is another object of the present invention to provide an image forming apparatus with reduced costs and improved reliability.

[0006]

According to one aspect of the present invention, there is provided an electrophotographic image forming apparatus having a developing device using a dry developer, wherein a toner hopper is provided on a developing device main body side. And a magnet roller as a replenishing roller at a position near a replenishing opening between the toner replenishing tank and the toner hopper. In a device having a scraper as a spike cutting means, there is provided a supply roller driving means capable of rotating the supply roller forward and backward, and the supply roller driving means comprises:
The replenishing roller is driven such that the relationship between the rotation angle A of the replenishing roller in the normal rotation direction and the rotation angle B of the reversal direction within a predetermined time is A <B. The invention of claim 2 is
A step-like gear in which a replenishing roller driving means of the image forming apparatus is formed by integrating a main body side driving source rotating in a fixed direction, and two sector gears rotated by the driving source; The reciprocating gear train includes a supply roller driving gear meshing with one sector gear of the stepped gear, and an idler gear train meshable with each sector gear at a different time. According to a third aspect of the present invention, an agitator is provided in the toner replenishing tank for supplying the toner in the toner replenishing tank toward the replenishing roller by rotating, and a main body side drive for rotating the agitator in a fixed direction. 2. The image forming apparatus according to claim 1, further comprising: a stepped gear having two sector gears, which are rotated in a predetermined direction by rotation of the main body side driving source, on a shaft of the agitator; The one sector gear and the supply roller gear are intermittently meshed with each other, and the other sector gear and the supply roller gear are meshed via an idler gear.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIGS. 1A and 1B are configuration diagrams of a developing device according to an embodiment of the present invention. The developing device 20 includes a developing roller 22 disposed in a developing frame 21 and facing a photoconductor (not shown). A developer replenishing device (toner replenishing tank) 24 is provided detachably connected to a replenishing port 23 located obliquely above the roller 22 (above the toner hopper 1A). A supply roller (magnet roller) 25 is disposed at a position directly above the supply port 23 with a predetermined gap therebetween so as to be rotatable in the direction of the arrow. A projecting scraper 26 is provided at a position facing the scraper 26, and the scraper 26 has a predetermined gap between the scraper 26 and the peripheral surface of the supply roller 25. An agitator 27 is disposed inside the toner supply tank 24 so as to be rotatable in the direction of the arrow.
The developer T at the bottom of the replenishing device is scraped up in the direction of the replenishing roller indicated by arrow A in cooperation with the thin film member 28 at the tip.
The scraped-up developer T is taken up by a supply roller 25 that is driven to rotate in the direction of the arrow, guided to a supply port 23, and supplied into the developing frame 1.

According to FIGS. 1 (a) and 1 (b), claims 1 to 3 will be described.
The forward and reverse rotation of the common supply roller (magnet roller) 25 will be described. In FIG. 1A, the replenishing roller 25 is rotating forward, and the toner T
Is sucked and conveyed by the supply roller 25 rotating forward (rotating clockwise = toner-discharge direction), and conveyed by the scraper 2.
A part of the toner layer on the supply roller 25 is scraped off by the roller 6, and the toner layer falls from the supply port 23 into the hopper 1A. FIG.
In (b), the replenishing roller 25 is rotating in the reverse direction (rotation in the counterclockwise direction = toner collecting direction), and when the toner in the hopper 1A has a predetermined amount or more, the toner in the hopper 1A is replenished. The toner is sucked by the rollers 25 and conveyed in the reverse direction, scraped off by the scraper 26 and returned into the toner replenishing tank 24. The replenishing roller 25 repeats forward and reverse rotations by a driving means as described below. The revolving rotation amount (rotation angle A) and the reverse rotation amount (rotation angle B) within a certain period of time during the toner replenishing operation. ) Is controlled so that forward rotation <reverse rotation. Specifically, for example, the control is performed at such a ratio that after two rotations, the rotation is reversed three times. When the replenishing roller rotates in the reverse direction, all toner in the hopper is removed from the toner replenishing tank 24.
The magnetic force of the supply roller as a magnet roller is set within a predetermined range so that the paper is not conveyed backward. The range of the magnetic force of the supply roller 25 as a magnet roller is set, for example, to such an extent that the toner amount in the hopper 1A falls within the illustrated position as shown in FIG. In other words, when the toner amount exceeds the height shown in the figure, the magnetic force is set to such an extent that the excess amount is sucked and transferred to the toner supply tank 24 side.

Next, embodiments corresponding to each claim will be individually described. First, FIG. 3 shows an embodiment corresponding to claim 1, and the invention of claim 1 is an electrophotographic image forming apparatus using a developing device using a dry developer, and a developing frame 1 of the developing device. The toner capacity that can be stored in the hopper 1A is assumed to be smaller than the toner capacity of the toner replenishing tank 24. In such a developing device, the toner is replenished in the toner replenishing tank 24 as a magnet roller. Roller 25 and scraper 2 as ear cutting means
6 is provided, and a replenishing roller driving means 32 capable of rotating the replenishing roller 25 in the normal direction and the reverse direction is provided. It is characteristic that the relationship between the rotation angle A in the turning direction (toner-discharge direction) and the rotation angle B in the reverse rotation direction (toner-recovery direction) is A <B.

FIG. 3 shows an example of the replenishing roller driving means 32 for setting the ratio of the amount of rotation in the forward direction and the reverse direction in this way.
(A), an agitator gear 27a and a supply roller gear 25a are rotatably supported outside one side end surface of the toner supply tank 24, and agitator driving means 31 (rotating in a certain direction). A shaft 31a and a gear 31b driven by a motor (not shown) and a supply roller driving means 32 (a shaft 32a and a gear 32b driven by a motor (not shown)) capable of rotating forward and backward are respectively provided with an agitator gear 27a. Each meshes with the roller gear 25a. Agitator driving means 31 and supply roller driving means 3
Reference numeral 2 is provided on the image forming apparatus main body side. The drive timing by each of the drive units 31 and 32 is, for example, as shown in FIG.
As shown in (b), while the agitator 27 operates continuously for a predetermined time t, the supply roller 25 is controlled so as to repeat forward rotation and reverse rotation three times. The control of the motors (different motors or the same motor) as the driving sources of the respective driving means 31 and 32 is performed by a control unit (not shown). By performing the control at the timing as shown in FIG. 3B, the forward / reverse operation of the supply roller described above is performed, and the toner amount in the hopper can always be kept within a certain range.

FIGS. 4 (a), 4 (b) and 4 (c) show an embodiment corresponding to the second aspect of the present invention. A side drive source (DC motor) 35, a gear box 36 having a built-in forward / reverse gear train for arbitrarily switching the output of the drive source 35 in the forward / reverse direction, and supplying the driving force from the gear box 36 It comprises a shaft 32a for transmitting to the roller gear 25a and a gear 32b. As shown in FIGS. 4 (b) and 4 (c), the gear box 36 (forward / reverse gear train) has an output shaft 35 of the drive source 35.
a, and a stepped gear 40 integrally formed with two sector gears 40A, 40B rotated by a drive source 35, and two sector gears 4 constituting the stepped gear 40.
0A or 40B (in this example, sector gear 4
0A) and a supply row configured and arranged to directly mesh with the supply row.
Drive gear 41 and the sector gear that is not meshed with the supply roller drive gear 41 of the stepped gear 40 (4 in this example).
0B) and a supply roller drive gear 41.
The supply roller driving gear 41 is directly connected to the shaft 32a of the supply roller driving means 32 shown in FIG. 4A or directly connected to the shaft of the supply roller gear 25a.

The stepped gear 40 rotates in one direction indicated by an arrow by the driving force from the driving source 35. In the course of the rotation, the sector gear A repeats meshing and disengaging with the supply roller driving gear 41, and the supply roller driving gear 41 is rotated in the direction of arrow A. Similarly, the sector gear B repeatedly engages with and disengages from the idler gear 42 to rotate the supply roller gear 41 in the direction of arrow B. As a result, the replenishment roller 25 driven by the replenishment roller drive gear 41 alternately repeats normal rotation and reverse rotation while the drive source 35 is rotating in a fixed direction. That is, when one sector gear 40A of the stepped gear meshes with the supply roller driving gear 41, the supply roller driving gear 41 rotates in the direction A, and the stepped gear further continues to rotate in the same direction to supply the sector gear 40A. After the engagement with the roller drive gear 41 is stopped, the other sector gear 4
0B meshes with the idler gear 42, and the supply roller drive gear 41 rotates in the B direction. It should be noted that the rotation amount in the direction A and B
The balance between the amount of rotation in the direction is determined by the relationship between the number of teeth of the sector gear 40A and the number of teeth of the sector gear 40B (FIG. 4).
(c)). In this embodiment, the supply roller driving means 32 is constituted by a main body side driving source 35 which rotates in a fixed direction, and a forward / reverse rotation gear train 36 provided on the main body side. A switching circuit or the like is not required, and a low-cost and highly reliable image forming apparatus can be provided.

Next, FIG. 5 shows another embodiment of the present invention corresponding to claim 3, and the stepped gear 4 of the embodiment shown in FIGS. 4 (b) and 4 (c).
0 is shared with the agitator gear 27a, and the supply roller gear 25a supported by the toner supply tank 24 can be intermittently engaged with the sector gear 40B. The gear can intermittently mesh with the sector gear 40A through the intermediary. While the sector gear 40B meshes directly with the supply roller gear 25a, the sector gear 40A meshes with the supply roller gear 25a via the idler gear 45. Therefore, while the step gear 40 rotates in a certain direction, the supply roller gear 25a rotates forward and reverse. Can be repeated. In other words, in this embodiment, the driving force from the driving source 35 (not shown) is directly transmitted to the stepped gear 4 which also serves as the agitator 27a.
0 to continuously rotate the agitator 27 in one direction while transmitting to the sector gear 40 of the stepped gear 40.
A and 40B are used to rotate the supply roller gear 25a forward and backward. For this reason, both sector gears 40
Due to the balance between the number of teeth A and the number of teeth 40B, driving at the timing as shown in FIG. 3B can be realized. In this embodiment, since the drive source of the agitator 27 can be the drive source 35 of the supply roller, the number of components can be reduced, and a low-cost and highly reliable image forming apparatus can be provided.

As described above, according to the present invention, there is provided an electrophotographic image forming apparatus using a developing device using a dry developer, wherein a toner capacity which can be stored in a hopper 1A of a developing frame 1 of the developing device. Is the toner in the toner supply tank 24.
When the amount of the toner in the hopper 1A is smaller than the capacity and the toner is returned to the toner supply tank side when the amount of toner in the hopper 1A becomes excessive,
When the developer cannot move into the inside of the hopper 1A, the density of the developer in the hopper 1A becomes extremely high. As a result, the fluidity of the developer deteriorates, and the toner to the developing unit (specifically, the developing roller) is transferred. -The problem that hinders smooth supply can be solved. That is, while the agitator for supplying the toner in the toner supply tank into the developing frame is rotating, the supply roller 2
5 is intermittently reversed, so that the supply roller 2
5, the balance between the amount of toner supplied to the developing frame 1 (hopper 1A) and the amount of toner returned to the toner supply tank 24 without being supplied to the developing frame 1 can be set appropriately. As a result, it is possible to prevent the fluidity of the toner in the hopper 1A from deteriorating, and to eliminate the problem of image fading. Further, since a large-scale remodeling of the developing device and the toner replenishing tank is not required, and only the gears need to be added to the outside, the cost can be reduced and the reliability can be improved. The present invention is not limited to the developing device described in the above embodiment, but can be applied to all magnetic powder conveying devices.

[0015]

As described above, in the first aspect, the toner amount in the hopper can be always kept to a predetermined amount or less by the forward / reverse rotation of the replenishing roller, and the deterioration of the fluidity of the toner in the hopper can be prevented. The amount of toner supplied to the developing roller can always be kept constant, and a small-sized image forming apparatus free from image blur can be provided. According to the second aspect of the present invention, since the supply roller driving means is constituted by a main body side driving source rotating in a fixed direction and a forward / reverse rotation gear train provided on the main body side, a switching circuit for reverse rotation of the driving source is provided. Becomes unnecessary, and a highly reliable image forming apparatus at lower cost can be provided. In the third aspect,
Since the drive source of the supply roller can be used as the drive source of the replenishment roller, the number of components can be reduced, and a low-cost and highly reliable image forming apparatus can be provided.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are diagrams illustrating the configuration and operation of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a case where a predetermined amount of toner is present in a hopper.

FIGS. 3A and 3B are views showing an example of a mechanism for rotating a replenishing roller forward and backward.

FIGS. 4A, 4B, and 4C are diagrams showing another example of a mechanism for rotating the supply roller forward and backward.

FIG. 5 is a diagram illustrating another example of a mechanism for rotating the replenishing roller forward and backward.

FIGS. 6A and 6B are diagrams showing a configuration of a conventional developing device which is a premise of the present invention.

[Description of Signs] 1 development frame, 1A toner hopper, 2 development roller, 3 supply port, 4 developer supply device (toner supply tank), 5 supply roller (magnet roller), 6 scraper, 7 agitator, 8 thin film, 20 Developing device,
21 developing frame, 22 developing roller, 23 supply port, 24 developer supply device (toner supply tank), 25
Supply roller (magnet roller), 26 scraper, 27 agitator, 28 thin film, 31 agitator
Drive unit, 32 supply roller drive unit, 35 body side drive source (DC motor), 36 gear box, 40 step gear, 40A, 40B sector gear, 41 supply roller
Drive gear, 42 idler gear,

Claims (3)

(57) [Claims] 1. An image forming apparatus of an electrophotographic type provided with a developing device using a dry developer, wherein a toner capacity that can be stored in a toner hopper on a developing device main body side is a toner replenishment that supplies toner to the toner hopper. A magnet roller as a replenishing roller, which is smaller than the toner capacity of the tank, and is located near a replenishing port between the toner replenishing tank and the toner hopper;
A replenishing roller driving means for rotating the replenishing roller forward and backward, wherein the replenishing roller driving means is provided within a predetermined time. An image forming apparatus characterized in that the supply roller is driven such that the relationship between the rotation angle A of the supply roller in the normal rotation direction and the rotation angle B of the supply roller in the reverse rotation direction is A <B. 2. The step of refill roller driving means of the image forming apparatus according to claim 1, wherein a main body side driving source rotating in a fixed direction and two sector gears rotated by said driving source are integrated. And a reversing gear train including a replenishing roller drive gear meshing with one sector gear of the stepped gear, and an idler gear meshable with each sector gear at a different time. Image forming device. 3. An agitator for supplying toner in the toner replenishing tank to the replenishing roller by rotating the toner replenishing tank, and a main body side driving source for rotating the agitator in a fixed direction is provided in the toner replenishing tank. 2. The image forming apparatus according to claim 1, wherein a stepped gear provided with two sector gears rotated in a predetermined direction by rotation of the main body side driving source is integrated with a shaft of the agitator. 2. The image forming apparatus according to claim 1, wherein the sector gear and the supply roller gear are intermittently engaged with each other, and the other sector gear and the supply roller gear are engaged via an idler gear.