JPH01116577A - Toner replenishing device - Google Patents

Abstract

PURPOSE:To execute an efficient toner replenishment and to equalize the image density by providing a toner peeling means divided and provided in the longitudinal direction of a toner replenishing roller and a control means for executing an ON/OFF control of the toner peeling means based on a signal from each toner concentration detecting means. CONSTITUTION:A toner scraping mechanism 18 is provided between an electrifying blade 16 and a seal blade 17, divided into two in the longitudinal direction of a toner replenishing roller 15, and constituted of a toner scraping mechanism 18a of the middle inner part side and a toner scraping mechanism 18b of this side. The toner scraping mechanism 18a is engaged to a solenoid 25a and a spring 26. Also, this mechanism is formed so that when the solenoid 25a is turned on, the tip of a scraping blade 22a turns and pressed against the toner replenishing roller 15, and when the solenoid 25a is turned off, the tip is separated by return force of the spring 26. The toner scraping mechanism 18b also consists of the same constitution. In such a way, the toner replenishment is executed efficiently, and the toner concentration in a developing device is equalized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toner replenishing device for a developing device used in an image forming apparatus such as a copying machine or a printer.

(Prior Art) Conventionally, this type of toner replenishment device was developed using the
As shown in Japanese Patent Application No. 99169, a toner hopper for storing toner is provided on the road blade of the developing device, and a toner replenishment roller is provided to close an opening formed at the bottom of the toner hopper. A toner has been proposed in which the toner is pre-charged by frictional contact with a charging blade and dropped into a developing device by a scraping blade.

In this toner replenishing device, the rotation of the toner replenishing roller is controlled on and off based on the toner replenishing signal from the toner concentration detecting means.

(Problems to be Solved by the Invention) Incidentally, in a developing device, the amount of toner consumed is not necessarily uniform across the width of the developing section because there are generally variations in the size of the original image and the density. For this reason, in the toner replenishing device, toner is replenished even to a developing section that does not require toner replenishment, resulting in uneven image density.

Therefore, two toner density sensors are provided in the width direction of the developing device, and the toner replenishment roller is divided in the longitudinal direction so as to face them, and each is provided so that it can be driven to rotate independently. Only the toner replenishment roller corresponding to the toner concentration detection sensor that has emitted the toner is driven to rotate, and toner is supplied only to the developing section that requires replenishment, thereby achieving efficient toner replenishment and uniform image density. It is possible to consider

However, dividing the toner replenishing roller in the longitudinal direction and independently driving the toner supply roller requires a complicated control method and structure, and also increases the size of the apparatus.

The present invention has been made in view of such problems, and an object of the present invention is to provide a toner replenishing device that has a simple structure, is easy to control, and can achieve uniform image density through efficient toner replenishment. purpose.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a toner replenishment system attached to a developing device that supplies toner to develop a latent image formed on an electrostatic latent image carrier. The apparatus includes a plurality of toner concentration detection means, a toner hopper that stores toner, a toner replenishment roller rotatably provided so as to close an opening provided below the toner hopper, and a toner replenishment roller that is in pressure contact with the toner replenishment roller. a charging blade for forming a toner layer of a constant thickness while charging the toner conveyed on the toner replenishment roller; The toner replenishing roller is divided in the longitudinal direction to correspond to the toner replenishing roller, and the toner peeling means peels off the toner layer on the toner replenishing roller and replenishes it into the developing device. and control means for controlling on/off of the toner peeling means corresponding to the toner peeling means.

(Function) Of the toner stored in the toner hopper, the toner on the outer peripheral surface of the toner replenishment roller is transported as the toner replenishment roller rotates, and when passing through the gap between the charging blade and the toner replenishment roller, the toner is transported by the charging blade. The toner is charged by frictional contact with the toner, and forms a toner layer with a constant thickness. and,
This charged toner layer is conveyed on a toner supply roller while facing inside the developing device.

Based on a toner replenishment signal from one of the toner concentration detection means, the control means turns on the toner stripping means corresponding to the toner concentration detection means. Then, the toner peeling means sequentially peels off portions of the charged toner layer that are being conveyed on the outer peripheral surface of the toner replenishing roller and are opposed to the toner peeling means, and supplies the charged toner layers into the developing device.

At this time, the toner is replenished within the area of the developing section detected by the toner concentration detection means that issued the toner replenishment signal.
Since toner is efficiently replenished only to the areas that require replenishment, the toner density becomes uniform.

Further, since the toner on the toner replenishment roller has passed through a charging grade and is sufficiently charged, and is formed in a layer with a constant thickness, it is replenished into the developing device at a constant rate and in a well-distributed manner.

(Example) Next, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a developing device (2) equipped with a toner replenishing device (1) according to the present invention, in which a developing sleeve (4) and a packet roller (5) are housed in a developing tank (3). .

The developing sleeve (4) is rotatably supported in the direction of arrow (a) so as to close an opening (3a) formed in the developer tank (3) from the inside, and has a portion exposed from the opening (3a). is formed to face the photoreceptor drum (6) with a predetermined gap therebetween.

Further, inside the developing sleeve (4), a magnetic roller (7) in which a plurality of magnets having magnetic poles extending in the axial direction are arranged alternately in N and S in the circumferential direction is housed in a fixed state. and,
Among the plurality of magnets, the negative magnet is disposed closest to the photosensitive drum (6), and the same polarity is disposed at the portion facing the packet roller (5).

Above the developing sleeve (4), a height regulating member (8) extends from the inner wall of the developing tank (3) and is formed to face the developing sleeve (4) with a predetermined gap therebetween. Further, a developing tank (
Toner concentration sensors (9a) and (9b) are respectively attached to the inner wall surface of 3) on the back side and the front side in FIG. 1.

The packet roller (5) has a plurality of packets (lO) attached in the longitudinal direction of the outer periphery, and is arranged parallel to the developing sleeve (4) on the opposite side of the photosensitive drum (6). It is supported so as to be rotatably driven in the direction of arrow (b). As shown in Fig. 3, this I-shaped roller (5) is rotationally driven by a motor (ll), and the developing sleeve (4) is also driven by a motor (11) with gears (12) and (13). It is designed to be rotationally driven through.

The toner replenishing device (1) includes a toner hopper (14), a toner replenishing roller (15), and a charging blade (16).
Seal blade (17) and toner scraping mechanism (18)
) and a control device (19).

The toner hopper (14) stores toner and is provided above the developer tank (3) so as to be located above the bucket/noodle roller (5).

The toner replenishment roller (15) is moved in the direction indicated by the arrow (c) so as to close the opening (14a) formed at the bottom of the toner hopper (14).
The lower half of its outer peripheral surface is exposed inside the developer tank (3), and the upper half is exposed inside the toner hopper (14).
) is formed so as to come into contact with the toner in the area.

The charging blade (16) is the opening of the toner hopper (14)! (14a), its lower end is oriented in the rotational direction (C) of the toner replenishment roller (15), and is in pressure contact with the toner replenishment roller (15).

The seal blade (17) is attached to the other edge of the opening (14a) of the toner hopper (14), and its oblique upper end is oriented in the rotational direction (C) of the toner replenishment roller (15). (15) is pressed against.

Therefore, the opening (14a) at the bottom of the toner hopper (14)
includes a toner supply roller (15) and a charging blade (16).
) and a seal blade (17).

The toner scraping mechanism (18) includes a charging blade (16)
and the seal blade (17), the toner supply roller (
The toner supply roller (15) is provided diagonally below the toner replenishment roller (15).
), and consists of a toner scraping mechanism (18a) on the back side in FIG. 1 and a toner scraping mechanism (18b) on the front side in FIG.

As shown in FIGS. 2 and 3, the toner scraping mechanism (18a) includes blade holding plates (21a) installed at both ends of a mouth-shaped frame (20).
a) A support member (23) protruding from the inner surface of the developer tank (3), on which the scraping blade (22a) is fixed;
(23) via pins (24), (24), and the middle part of the frame (20) is attached to the solenoid (
25a) and a spring (26). and,
When the solenoid (25a) is turned on, the tip of the scraping blade (22a) rotates in the direction of arrow (d) in FIG.
When a) is turned off, the tip of the scraping blade (22a) rotates in the direction of arrow (d') in FIG. has been done. Toner scraping mechanism (18b
) also has a similar configuration, but the suffix b is added instead of the suffix a in the numbers of the scraping blade and solenoid, and the explanation will be omitted.

As shown in FIG. 3, the control device (19) controls the rotation of a motor (27) that drives the toner supply roller (15), and also controls the toner concentration sensors (9a) and (9b).
) The toner scraping mechanism (18a
), (18b) each solenoid (25a), (25b)
can be turned on or off.

In the developing device (2) having the above configuration, 2gc of developer consisting of toner and carrier is used. It is assumed that the toner is stored in the toner hopper (14).

7 In this state, when the print switch is turned on,
The photosensitive drum (6) rotates in the direction of arrow (e) based on the drive of the main motor (not shown), and the motor (
11) and (27) are driven, and the developing sleeve (4) and packet roller (5) move in the direction of arrows (a) and (b), respectively.
) direction.

As a result, in the developer tank (3), the developer scooped up by the packet (lO) of the packet roller (5) rotating in the direction of arrow (b) is released toward the developer sleeve (4). Then, the carrier in the developer supplied onto the outer surface of the developing sleeve (4) is transferred to the magnetic roller (7).
) along with the toner while being held by the magnetic force of arrow (a)
conveyed in the direction.

The conveyance amount of the developer on the developing sleeve (4) is first regulated by the brush height regulating member (8), and the dammed developer is transferred to the following developer in the space behind the spike height regulating member (8). The toner and carrier are mixed and stirred, and the toner and carrier are charged positively and negatively, respectively.

Note that here, the toner concentration in the developer is detected by a toner concentration sensor (9).

The developer that has passed through the height regulating member (8) is conveyed in the direction of arrow (a) in the state of a magnetic brush, and the carrier passes through each magnetic pole facing portion and is subjected to strong and weak magnetic forces, thereby further separating the carrier and toner. are mixed and stirred, and charged to a developable state.

In this way, when it rotates around the developing sleeve (4) and reaches the same polar opposite part of the magnetic roller (7), it loses its magnetic holding force and moves to the developing tank (3) on the packet roller (5) side. It will be collected. Also within this developing tank (3), toner and carrier are mixed and stirred based on the operation of the packet (IO) of the packet roller (5) in the direction of arrow (b).

In the above state, the document image is scanned, an electrostatic latent image is formed on the surface of the photoreceptor drum (6), and the electrostatic latent image moves to the part facing the developing sleeve (4). Then, the developer on the developing sleeve (4) is rubbed by the magnetic brush and developed.

As a result of this developing operation, for example, the toner of the developer on the back side in FIG. 1 is consumed and the toner concentration decreases, and the toner concentration sensor (9a) detects this and issues a toner replenishment signal to the control device (19). .

below,! It! l Toner concentration detection sensor (9a
) and a toner scraping mechanism (18a).
The toner replenishment operation (19) will be explained according to the flowchart shown in FIG. 4 and the time chart shown in FIG.

In step (5101), it is determined whether the toner replenishment signal is on, that is, whether the toner concentration sensor (9a) has detected a low density, and if the toner replenishment signal is on, step (S l 02) is performed. Toner replenishment roller (15)
Turn on.

As a result, in the toner hopper (14), as the toner replenishment roller (15) rotates in the arrow (c) direction, the toner in contact with the toner replenishment roller (15) is transported in the arrow (C) direction and transferred to the charging blade ( 16) and the toner supply roller (15), the charging blade (16)
By frictional contact with the toner, the toner is charged to a positive polarity and forms a charged toner layer with a constant thickness. This charged toner layer is conveyed in the direction of the arrow (C) on the toner supply roller (15), passes through the toner scraping mechanism (18a) which is in the off state, passes through the seal blade (17), and passes through the toner hopper (1).
4), and further passes through the charging blade (16) to be charged in the same manner as described above. In this way, the toner on the toner supply roller (15) is transferred to the charging blade (
16) and is sufficiently pre-charged, it circulates until the toner scraping mechanism (18a) is turned on.

Next, in step (S103) it is determined whether the solenoid (25a) is on. Here, the solenoid (2
5a) is off, in step (S104) the toner on the toner replenishing roller (15) is transferred to the charging blade (]6).
Determine whether it has passed twice or more, and if it has not passed, simply return. As a result, even if the toner replenishment signal is on, the solenoid (25a) remains off until the toner passes through the charging blade (16) two or more times.

Further, if the toner on the toner supply roller (15) has passed through the charging blade (16) twice or more, step (s
105) turns on the solenoid (25a). This causes the frame (20) to engage with the solenoid (25a).
rotates in the direction of arrow (d) in FIG. 2, and the tip of the scraping blade (22a) comes into pressure contact with the toner supply roller (15). Therefore, the charged toner layer of a certain thickness that had been formed on the outer peripheral surface of the toner replenishing roller (15) on the back side in FIG. 1 is scraped off, and as shown in FIG. It is supplied to the back side. At this time, the toner supply roller (15
) is in a charged state and is formed in a layer with a constant thickness, so it is continuously replenished to the back side of the developing tank (3) at a constant rate and with good dispersion.

During this toner replenishment operation, step (
5103) and the solenoid (25a) is on, so
In step (S106), it is determined whether or not the toner replenishing roller (15) has completed one revolution since the solenoid (25a) was turned on. If it has not completed one revolution, the process returns to continue the toner replenishing operation.

Furthermore, if the toner supply roller (15) has completed one rotation, the solenoid (25a) is turned off in step (S107). As a result, the toner scraping mechanism (18a)
No. 7 Re-A (20) Kabane (26) j:,! :t) The scraping blade (22) is pulled back in the direction of the arrow (d').
The tip of a) separates from the toner supply roller (15).

Therefore, the charged toner layer on the outer circumferential surface of the toner replenishing roller (15) on the back side in FIG. .

If the toner on the toner supply roller (15) passes through the charging blade (16) twice or more, step (S1
04) and then in step (S105), the solenoid (
25a) and continue the toner replenishment operation in the same manner as described above. As a result, only the toner for one rotation of the toner supply roller (15), that is, the toner that has passed through the charging blade (16) twice or more and has been sufficiently pre-charged, is scraped off, and the toner in the developer tank (3) is scraped off. It will be supplied to the back of Figure 1.

As shown in Fig. 5, the above toner replenishment operation is performed by repeatedly turning on and off the solenoid (25) at regular intervals while the toner replenishment signal from the toner concentration sensor (9a) is on. It will be held in

The replenished toner is supplied by the packet roller (5) to the back side where the toner concentration on the developing sleeve (4) is decreasing, so the toner concentration of the developer on the developing sleeve (4) decreases from the back side. Equalized over the entire area on the near side.

Further, the toner newly supplied to the back side of the developing sleeve (4) is sufficiently charged by passing through the charging blade (16) twice or more on the toner replenishing roller (15) in advance, and is replenished in a well-distributed manner. Therefore, there is no charge failure or poor dispersion on the developing sleeve (4), and a beautiful image without developer bumps, unevenness, or fog can be obtained.

In this way, toner is replenished and the developing sleeve (4
) becomes high on the outer circumferential surface on the back side in FIG. 1, the toner concentration detection sensor (9a) detects this and issues a toner replenishment stop signal to the control device (19).

Then, since the toner replenishment signal is off in step (S101), the toner replenishment roller (15) is turned off in step (S108), the solenoid (25) is turned off in step (S109), and the process returns.

On the other hand, the toner concentration detection sensor (9b) on the front side in Fig. 1
and a toner scraping mechanism (18b).
Since the toner replenishment operation in 9) is performed in the same manner as above,
The explanation will be omitted.

Incidentally, in the above embodiment, regardless of whether the main motor is on or off, if the toner replenishment signal is raised, the toner replenishment roller (15) is turned on, and the solenoid (25) is further turned on to perform toner replenishment. Because it is,
Even if the main motor is turned off without replenishing toner while the toner density is low after copying a document with a high black-and-white ratio, the toner density sensor (
9) issues a toner replenishment signal, toner replenishment becomes possible. Therefore, at the time of the next copying, the toner density has been recovered and an image with appropriate density can be obtained.

In the above embodiment, the toner is mechanically scraped off by a toner scraping mechanism (18) consisting of a scraping blade (22) and a solenoid (25) as the toner peeling means. As shown in FIG. 7, a conductive roller (28) whose rear side and front side are electrically insulated via an insulating member is disposed below the toner supply roller (15) with a predetermined gap between them. Conductive roller (28)
is formed so that it can be driven to rotate at the same time as the toner replenishment roller (15) by a motor (27), and the opposite polarity to the toner is applied to the back and front sides of the conductive roller (15) based on each toner replenishment signal. That is, it is formed so as to apply a negative voltage (V), and the toner replenishing roller (1
5) The toner on the toner may be electrostatically peeled off by a -H conductive roller (28) and then scraped off by a scraping blade (29).

In this case, the solenoid (25a) in the above embodiment,
(25b) is turned on and off, the toner supply roller (
15) When the upper toner passes through the charging blade (16) twice or more, turn on the power circuit to the back side or the front side of the conductive roller (28), and then turn on the toner supply roller (15).
It is sufficient to turn off the power supply circuit when the rotation has been made approximately one revolution.

In FIGS. 6 and 7, the components other than the toner peeling mechanism (30) are the same as those in the embodiment shown in FIGS. 1 and 3, and therefore the description thereof will be omitted.

Further, in the above embodiment, the toner replenishment roller (15) is turned on based on the toner replenishment signal from the toner concentration sensor (9), but when the main motor is turned on,
Alternatively, the toner supply roller (15) may be turned on. As a result, even if the toner replenishment signal is not set, as long as the main motor is driving, the toner replenishment roller (
15) A charged toner layer is formed on the top, so if the toner replenishment signal is on, the solenoid (2
5) is turned on, resulting in faster response.

In the above embodiment, the toner density sensor provided in the developing device is used as the toner density detecting means to detect the toner density in the developing device, and toner replenishment control is performed based on this detection signal. However, as a toner density detection means, the image density of a predetermined latent image pattern formed on the photoreceptor drum after development is detected by an image density sensor provided on the photoreceptor drum side, and based on this detection signal. The present invention can be applied to devices that perform toner replenishment control.

(Effects of the Invention) As is clear from the above description, according to the present invention, a plurality of toner concentration detection means are provided, and a toner peeling means is provided separately to correspond to each of the toner concentration detection means. , a charged toner layer of a constant thickness is formed on the toner replenishment roller by a charging blade, and based on a toner replenishment signal from one of the toner concentration detection means, the toner concentration at which the toner replenishment signal is issued by the control means is determined. The toner peeling means corresponding to the detection means is turned on and off to peel off the charged toner layer that has passed through the charging blade, thereby replenishing toner only to the portions that require replenishment.

Therefore, the toner supply roller should be rotated integrally.
Since it is only necessary to turn on and off one of the toner peeling means provided separately in the longitudinal direction of this toner supply roller, the drive mechanism is simple and control is easy. Also,
Toner is efficiently replenished and the toner concentration within the developing device is made uniform. Furthermore, since the sufficiently charged toner that has passed through the charging blade is replenished into the developing device at a constant rate with good dispersion, toner with poor charging and dispersion will not be replenished into the developing device. This has the effect of making it possible to obtain beautiful images without toner run-off, fogging, or unevenness.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a developing device equipped with a toner replenishing device according to the present invention, and FIG. 2 is a sectional view showing a toner scraping mechanism.
Figure 3 is a plan view of the developing device shown in Figure 1, Figures 4 and 5.
6 is a sectional view of a developing device equipped with a toner replenishing device according to another embodiment of the present invention, and FIG. 7 is a sectional view of the developing device shown in FIG. 6. FIG. l... Toner supply device, 2... Developing device, 9a, 9
b... Toner concentration sensor, 14... Toner hopper, 15... Toner supply roller, 16... Charging blade, l8a, l8b...
・Toner scraping mechanism (toner peeling means), 19...
Control device. Patent applicant Minolta Camera Co., Ltd. Agent
People Patent Attorneys Aobai Ao and 2 others Figure 3 Figure 6 Figure 7

Claims (1)

[Claims] (1) A toner replenishing device attached to a developing device that supplies toner to develop a latent image formed on an electrostatic latent image carrier, which includes a plurality of toner concentration detection means, a toner hopper that stores toner, and a toner hopper that stores toner. A toner replenishment roller is rotatably provided so as to close an opening provided at the bottom of the toner hopper, and a toner replenishment roller is provided in pressure contact with the toner replenishment roller to charge the toner conveyed on the toner replenishment roller while maintaining a constant thickness. A charging blade that forms a toner layer, and a toner replenishing roller that is divided in the longitudinal direction of the toner replenishing roller and provided on the downstream side of the charging blade in the rotational direction of the toner replenishing roller so as to correspond to each of the toner concentration detection means. The toner peeling means peels off the upper toner layer and replenishes it into the developing device, and the control means performs ON/OFF control of the corresponding toner peeling means based on the signal from each toner concentration detection means. A toner replenishing device characterized by: