JPH01116574A - Toner replenishing device - Google Patents

Abstract

PURPOSE:To constitute the title device so that a toner is pre-electrified adequately, and also, dispersed satisfactorily and replenished into a developing device by providing a means for executing a control for turning on a toner peeling means based on a signal from a toner concentration detecting means, and thereafter, turning off the toner peeling means at the time point when a toner replenishing roller has made about one rotation. CONSTITUTION:A toner replenished operation is executed at a prescribed interval by a fact that a solenoid 25 repeats ON and OFF at a prescribed period, while a toner replenishing signal from a toner concentration sensor 9 is setting. The replenished toner is supplied onto a developing sleeve 4 by a bucket roller 5, carried to the opposed part to a photosensitive drum 6 and offered for the development, and the toner is adequately electrified in advance by passing through an electrifying blade 16 two times or more on a toner replenishing roller 15, dispersed satisfactorily and replenished, therefore, electrification failure and dispersion failure do not occur on the developing sleeve 4.

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 includes a toner hopper that stores toner on the path of a developing device, a toner replenishment roller that closes an opening formed at the bottom of the toner hopper, and By providing a notch groove in the axial direction of the outer peripheral surface of the toner replenishment roller and rotating the toner replenishment roller appropriately, the toner in the toner hopper is taken in while the notch groove faces the toner hopper, and the toner is drawn downward. Some devices are designed to cause the toner to fall into the developing device when it reaches the developing device.

(Problems to be Solved by the Invention) However, in the developing device equipped with the conventional toner replenishing device, the toner taken into the notch groove on the toner replenishing roller falls into the developing device in a solid state. There were problems such as poor toner dispersion within the developing device, unevenness and fogging of images, and toner smearing.

For this reason, as shown in Japanese Utility Model Application Publication No. 61-99169, a charging blade and a scraping blade are pressed into contact with the toner replenishment roller, and the toner is pre-charged by frictional contact with the charging blade, and the scraping blade is used to pre-charge the toner. A device in which the image forming apparatus is dropped into a developing device has been proposed.

However, 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 detection means. That is, only when a toner replenishment signal is issued, the toner replenishment roller rotates and toner is replenished. Therefore, after the toner replenishment signal is issued, the toner on the toner replenishment roller is
The toner is charged only after passing through the charging blade, and once the toner has passed through the charging blade, it is immediately scraped off by the scraping blade, so it cannot be said that the preliminary charging of the toner is necessarily sufficient.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner replenishing device in which toner is sufficiently precharged, well dispersed, and replenished into a developing device.

(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 device includes 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 provided in pressure contact with the toner replenishment roller and conveyed on the toner replenishment roller. A charging blade is provided downstream of the charging blade in the rotational direction of the toner replenishment roller to form a toner layer of a constant thickness while charging the toner to be applied to the toner. When the toner on the toner replenishing roller passes through the charging blade twice or more, the toner removing means is turned on based on signals from the toner replenishing roller and the toner concentration detecting means, and then the toner replenishing roller is turned on. and control means for controlling the toner peeling means to be turned off after approximately one rotation.

(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 the toner replenishment signal from the toner concentration detection means,
The control means turns on the toner peeling means after the toner on the toner supply roller passes through the charging blade two or more times. Then, the toner peeling means sequentially peels off the charged toner layer being conveyed on the outer circumferential surface of the toner replenishment roller and replenishes it into the developing device. At this time, the toner on the toner replenishment roller has passed through the charging blade two or more times and is sufficiently charged, and is formed in a layer of a constant thickness, so it is distributed well in the developing device at a constant rate. will be replenished.

During this toner replenishment operation, when the toner replenishment roller makes approximately one rotation and all the toner that has passed through the charging blade twice or more is peeled off, the control means turns off the toner peeling means. Then, after waiting until the toner on the toner replenishing roller passes through the charging blade two or more times, the control means turns on the toner peeling means and repeats the same toner replenishing operation as described above.

Therefore, only toner that has passed through the charging blade twice or more and has been sufficiently charged is replenished into the developing device.

(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 (
A toner concentration sensor (9) is attached to the inner wall surface of 3).

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 packet roller (5) is rotationally driven by a motor (ll), and the developing sleeve (4) is also rotated by a motor (11) via gears (12) and (13). It is designed to be driven.

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 packet 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 attached to one edge of the opening (14a) of the toner hopper (14), and its lower end is oriented in the rotational direction (C) of the toner replenishment roller (15). 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 (
15), and as shown in FIGS. 2 and 3, a blade holding plate (21) is installed at both ends of a U-shaped frame (20), and a blade holding plate (21) is installed on both ends of the U-shaped frame (20). The scraping blade (22) is fixed to the developer tank (
3) on the supporting members (23), (23) protruding from the inner surface of the
It is swingably attached via pins (24), (24),
The middle part of the frame (20) is engaged with the solenoid (25) and the spring (26). And the solenoid (2
5), the tip of the scraping blade (22) rotates in the direction of arrow (d) in FIG.
15) and when the solenoid (25) is turned off, the tip of the scraping blade (22) will move as shown by the arrow (d' in Figure 2).
The toner replenishing roller (15) is configured to rotate in the direction and detach from the toner replenishing roller (15) by the return force of the spring (26).

As shown in FIG. 3, the control device (19) controls the rotation of a motor (27) that drives the toner replenishment roller (15), and also controls the toner replenishment signal or toner replenishment stop signal of the toner concentration sensor (9). The solenoid (25) of the toner scraping mechanism (18) is turned on or off based on the signal.

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

In this state, when the print switch is turned on, the photosensitive drum (6) is driven by the main motor (not shown).
rotates in the direction of the arrow (8), and the motor (11)
, (27) are driven, and the developing sleeve (4) and packet roller (5) rotate in the directions of arrows (a) and (b), respectively.

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 peripheral surface of the developing sleeve (4) is transferred to the magnetic roller (
7) while being held by the magnetic force of arrow (a) along with the toner.
) 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 (lO) 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.

When the toner of the developer is consumed by this developing operation and the toner concentration decreases, the toner concentration sensor (9) detects this and issues a toner replenishment signal to the control device (19).

The toner replenishment operation will be explained below according to the flowchart shown in FIG. 4 and the time chart shown in FIG.

In step (SIOI), it is determined whether or not the toner replenishment signal is on, that is, whether or not the toner density sensor (9) has detected low density. If the toner replenishment signal is on, the toner replenishment signal is determined in step (5102). Turn on the supply roller (15).

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 arrow (c) on the toner supply roller (15), passes through the toner scraping mechanism (18) which is in the off state, passes through the seal blade (17), and passes through the toner hopper (14).
) and further passes through the charging blade (16) where it is charged in the same manner as described above. In this way, the toner on the toner replenishment roller (15) is transferred to the charging blade (15) every rotation.
6), and while being sufficiently pre-charged, the toner scraping mechanism (18) circulates until the toner scraping mechanism (18) is turned on.

Next, in step (S103) it is determined whether the solenoid (25) is on. Here, the solenoid (2
5) is off, it is determined in step (S104) whether the toner on the toner supply roller (15) has passed through the charging blade (16) two or more times, and if it has not passed, the process returns directly. . As a result, even if the toner replenishment signal is on, the toner will hit the charging blade (16) twice.
The solenoid (25) remains in the OFF state and waits until it passes through the vehicle more than once.

Further, if the toner on the toner supply roller (15) has passed through the charging blade (16) twice or more, step (s
At t05), the solenoid (25) is turned on.

This causes the frame (
20) rotates in the direction of arrow (d) in FIG. 2, and the tip of the scraping blade (22) comes into pressure contact with the toner supply roller (15). Therefore, the charged toner layer of a constant thickness formed on the toner supply roller (15) is scraped off and replenished into the developer tank (3) as shown in FIG. At this time, the toner on the toner replenishment roller (15) is in a charged state and is formed in a layer with a constant thickness, so it is continuously replenished into the developer tank (3) at a constant rate with good dispersion. .

During this toner replenishment operation, step (
Since the solenoid (25) is turned on in step S103), it is determined in step (s+06) whether or not the toner concentration sensor (15) has completed one rotation since the solenoid (25) was turned on. If so, the program returns and continues the toner replenishment operation.

Furthermore, if the toner supply roller (15) has completed one rotation, the solenoid (25) is activated in step (S I O7).
Turn off. As a result, the toner scraping mechanism (18)
The frame (20) and the spring (26) cause the arrow (do)
The tip of the scraping blade (22) separates from the toner supply roller (15). Therefore, the charged toner layer on the toner supply roller (15) is transported in the direction of arrow (c) without being scraped off, and furthermore, the charged toner layer on the toner supply roller (15) is transported in the direction of arrow (c).
6), it circulates while being pre-charged.

If the toner on the toner supply roller (15) passes through the charging blade (16) twice or more, step (51)
04) and then in step (5105), the solenoid (
25) 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 replenishing 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 replenished into the developer tank (3). will be done.

In the above-described toner replenishment operation, as shown in FIG. 5, the solenoid (25) is turned on at regular intervals while the toner replenishment signal from the toner concentration sensor (9) is on.

By repeating off and on, it will be done at regular intervals.

The replenished toner is supplied onto the developing sleeve (4) by the packet roller (5) and conveyed to the part facing the photoreceptor drum (6) for development. It has passed through the charging blade (16) twice or more at the top, has been sufficiently charged, and has been replenished in a well-distributed manner.
There is no charging failure or poor dispersion on the developing sleeve (4), and a beautiful image without developer lumps, unevenness, or fog can be obtained.

In this way, toner is replenished and the developing sleeve (4
) becomes high, the toner concentration detection sensor (9) detects this and issues a toner replenishment stop signal to the control device (19).

Then, since the toner replenishment signal is off in step (SIOI), the toner replenishment roller (15) is turned off in step (S108), the solenoid (25) is turned off in step (Sl'09), and the process returns.

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) is disposed below the toner supply roller (15) with a predetermined gap, and the conductive roller (28)
is configured to be rotatably driven by a motor (27) at the same time as the toner replenishment roller (15), and is configured to apply a voltage (V) of opposite polarity to the toner, that is, a negative voltage (V), based on a toner replenishment signal; Alternatively, the toner on the toner replenishing roller (15) may be electrostatically peeled off by the conductive roller (28) and then scraped off by the scraping blade (29).

In this case, similar to the turning on and off of the solenoid (25) in the above embodiment, when the toner on the toner replenishing roller (15) passes through the charging blade (16) twice or more, the conductive roller (28) is turned on and off. It is sufficient to turn on the power supply circuit and then turn off the power supply circuit when the toner replenishing roller (15) has made approximately one revolution.

In FIGS. 6 and 7, the components other than the toner peeling mechanism (18a) 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 charged toner layer of a constant thickness is formed on the toner replenishment roller by the charging blade, and the control means By turning the toner peeling means on and off, the charged toner layer that has passed through the charging blade twice or more is peeled off.

Therefore, toner that has passed through the charging blade twice or more and has been sufficiently charged is replenished into the developing device at a constant rate with good dispersion, so toner with poor charging 9 and poor dispersion will not be replenished into the developing device. This has the effect that it is possible to obtain beautiful images without toner bumps, fog, 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 replenishing device, 2... Developing device, 9...
Toner concentration sensor, 14... Toner hopper, 15...
・Toner supply port=U, 16...Charging blade, 18・
... Toner scraping mechanism (toner peeling means), 19...
·Control device. Page 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 toner hopper that accommodates toner and an opening provided below the toner hopper. a toner replenishment roller rotatably provided to block the toner replenishment roller, and a charging blade provided in pressure contact with the toner replenishment roller to form a toner layer of a constant thickness while charging the toner conveyed on the toner replenishment roller. , a toner peeling means provided downstream of the charging blade in the rotational direction of the toner replenishing roller, for peeling off the toner layer on the toner replenishing roller and replenishing it into the developing device, and a toner concentration detecting means based on a signal from the toner peeling means, a control means that turns on the toner peeling means when the toner on the toner replenishment roller passes the charging blade two or more times, and then turns off the toner peeling means when the toner replenishment roller has made approximately one rotation; A toner replenishing device characterized by comprising: