JP2596011B2 - Toner supply device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply device of a developing device used for an image forming apparatus such as a copying machine and a printer.

2. Description of the Related Art Conventionally, as a toner replenishing device of this type, a toner hopper for storing toner is provided substantially above a developing device, and a toner replenishing roller is provided so as to close an opening formed at the bottom of the toner hopper. By providing a notch groove in the axial direction of the outer peripheral surface of the toner supply roller, and by appropriately rotating the toner supply roller, the toner in the toner hopper is taken in while the notch groove faces the toner hopper,
There is one in which the toner is dropped into the developing device when it comes down.

(Problems to be Solved by the Invention) However, in the developing device provided with the conventional toner replenishing device, since the toner taken in the notch groove on the toner replenishing roller drops into the developing device in a solid state,
Dispersion of the toner in the developing device becomes poor, resulting in unevenness in the image.
There have been problems such as fogging and toner bleeding.

For this reason, as shown in Japanese Utility Model Laid-Open Publication No. 61-99169, the charging blade and the scraping blade are pressed against the toner replenishing roller, and the toner is pre-charged by frictional contact with the charging blade. There has been proposed one that is dropped into a developing device.

However, in this toner replenishing device, the rotation of the toner replenishment roller is controlled to be on or off based on a toner replenishment signal from the toner density detecting means. That is, the toner supply roller rotates to supply toner only when the toner supply signal is issued. Therefore, the toner on the toner supply roller is charged only after passing through the charging blade after the toner supply signal is issued, and the toner once passing through the charging blade is immediately scraped off by the scraping blade. Is not sufficient.

The present invention has been made in view of the above problems, and has as its object to provide a toner replenishing device in which toner is sufficiently pre-charged, and is 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 supply device provided with a developing device for supplying toner to a latent image formed on an electrostatic latent image carrier and developing the latent image. In the apparatus, a toner hopper for storing toner, a toner supply roller provided to close an opening provided below the toner hopper, a toner supply roller that is driven to rotate in conjunction with driving of a main motor of the developing device, and a toner supply roller provided in pressure contact with the toner supply roller A charging blade for forming a toner layer having a constant thickness while charging the toner conveyed on the toner replenishing roller, and a toner layer provided on the toner replenishing roller downstream of the charging blade in the rotation direction of the toner replenishing roller. A toner peeling unit for peeling off the toner and supplying the toner to the developing device; and a control unit for controlling on / off of the toner peeling unit based on a signal from the toner density detecting unit. Those having a means.

(Operation) With the driving of the main motor of the developing device, the toner supply roller rotates, and the toner on the outer peripheral surface of the toner supply roller among the toner stored in the toner hopper is conveyed with the rotation of the toner supply roller. When passing through the gap between the charging blade and the toner supply roller, the toner is charged by frictional contact with the charging blade and forms a toner layer having a constant thickness. The charged toner layer is conveyed on the toner supply roller while facing the inside of the developing device.

When the control unit turns on the toner removing unit based on the toner supply signal from the toner concentration detecting unit, the toner removing unit sequentially removes the charged toner layer being conveyed on the outer peripheral surface of the toner supply roller and enters the developing device. Replenish. At this time, the toner on the toner replenishing roller is charged and formed in a layer having a constant thickness, so that the toner is continuously replenished into the developing device at a constant rate with good dispersion. Even if the control unit turns off the toner removing unit based on the toner replenishment stop signal from the toner concentration detecting unit, the toner replenishment roller continues to rotate as long as the main motor is driven. On the outer peripheral surface, as above,
A charged toner layer having a constant thickness is formed by the charging blade. Therefore, even if a toner supply signal is issued after that,
The toner which is sufficiently charged and formed into a layer having a constant thickness is supplied.

Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

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

The developing sleeve (4) is rotatably supported in the direction of the arrow (a) so as to close the opening (3a) formed in the developing tank (3) from the inside, and a part exposed from the opening (3a). Are formed so as to face the photosensitive drum (6) with a predetermined gap.

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 alternately arranged N and S in the circumferential direction is housed in a fixed state. And
One of the plurality of magnets is disposed so as to be closest to the photosensitive drum (6), and the same pole is disposed at a portion facing the bucket roller (5).

Above the developing sleeve (4), a spike 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. A toner concentration sensor (9) is attached to the inner wall surface of the developing tank (3) which forms a space on the upstream side in the rotation direction of the developing sleeve (4) from the ear height regulating member (8).

The bucket roller (5) has a plurality of buckets (10) attached in the longitudinal direction of the outer periphery, and is parallel to the developing sleeve (4) on the side opposite to the photosensitive drum (6) with respect to the developing sleeve (4). And supported so as to be rotatable in the direction of arrow (b). The bucket roller (5) is rotated by a motor (11) as shown in FIG.
The developing sleeve (4) is also driven to rotate by a motor (11) via gears (12) and (13).

The toner supply device (1) includes a toner hopper (14), a toner supply roller (15), a charging blade (16), a seal blade (17), a toner scraping mechanism (18), and a control device (19). It consists of

The toner hopper (14) contains toner and is provided above the developing tank (3) so as to be located above the bucket roller (5).

The toner replenishing roller (15) is rotatably supported in the direction of arrow (c) so as to close an opening (14a) formed at the bottom of the toner hopper (14). ), And the upper half thereof is formed so as to be in contact with the toner in the toner hopper (14).

The charging blade (16) is attached to one edge of the opening (14a) of the toner hopper (14), and its lower end is directed in the rotation direction (c) of the toner supply roller (15). 15) is pressed against.

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 directed in the rotation direction (c) of the toner supply roller (15). It is pressed against (15).

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

The toner scraping mechanism (18) includes a toner supply roller (15) between the charging blade (16) and the seal blade (17).
Is provided diagonally below, as shown in FIGS. 2 and 3.
Blade holding plate (21) at both ends of U-shaped frame (20)
Is fixed to the blade holding plate (21) and the scraper blade (22) is fixed thereto. The pins (23) and (23) projecting from the inner surface of the developing tank (3) are pinned on the blade holding plate (21). 24), (24)
And an intermediate portion of the frame (20) is engaged with a solenoid (25) and a spring (26).
When the solenoid (25) is turned on, the tip of the scraping blade (22) rotates in the direction of the arrow (d) in FIG. 2 to come into pressure contact with the toner replenishing roller (15), and when the solenoid (25) is turned off. The tip of the scraping blade (22) is formed so as to rotate in the direction of the arrow (d ') in FIG. 2 and separate from the toner supply roller (15) by the return force of the spring (26).

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

In the developing device (2) having the above configuration, a two-component developer including a toner and a carrier is used. A predetermined amount of the developer is stored in the developing tank (3) in advance, and the toner is replenished. Is stored in the toner hopper (14).

In this state, when the print switch is turned on, the photosensitive drum (6) rotates in the direction of the arrow (e) based on the driving of the main motor (not shown), and the motors (11) and (27) are driven. , The developing sleeve (4), the bucket roller (5) and the toner replenishing roller (15) rotate in the directions of arrows (a), (b) and (c), respectively.

As a result, in the developing tank (3), the developer scooped by the bucket (10) of the bucket roller (5) rotating in the direction of the arrow (b) is discharged toward the developing sleeve (4). Then, the carrier in the developer supplied on the outer peripheral surface of the developing sleeve (4) is transported together with the toner in the direction of the arrow (a) while being held by the magnetic force of the magnetic roller (7).

The transport amount of the developer on the developing sleeve (4) is firstly regulated by the spike height regulating member (8), and the blocked developer is the developer that follows in the space behind the spike height regulating member (8). And the fluid flows in a vortex, mixing the toner and the carrier,
Stirring is performed, and the toner is positively charged and the carrier is negatively charged. Here, the toner concentration in the developer is detected by the toner concentration sensor (9).

The developer that has passed through the hot height regulating member (8) is indicated by an arrow (a).
The carrier is conveyed in a magnetic brush state in the direction, and the carrier passes through the respective magnetic pole opposing portions and receives a strong magnetic force, so that the carrier and the toner are further mixed and agitated, and charged to a state in which development is possible.

In this way, when the developing sleeve (4) is rotated about once and reaches the same-polarity opposed portion of the magnetic roller (7), the magnetic holding force is lost and the developing tank (3) on the bucket roller (5) side is lost. Collected. In the developing tank (3), the toner and the carrier are mixed and agitated based on the operation of the bucket (10) of the bucket roller (5) in the direction of the arrow (b).

On the other hand, in the toner hopper (14), as the toner supply roller (15) rotates in the direction of the arrow (c), the toner in contact with the toner supply roller (15) is conveyed in the direction of the arrow (c) and is charged by the charging blade (16). ) And the toner supply roller (15), the toner is charged to a positive polarity by frictional contact with the charging blade (16) and forms a charged toner layer having a constant thickness. This charged toner layer is conveyed in the direction of arrow (c) on the toner replenishing roller (15), passes through the toner scraping mechanism (18) in the OFF state, passes through the seal blade (17), and passes through the toner hopper (14). And then passes through the charging blade (16) to be charged as described above. In this way, the toner on the toner replenishing roller (15) goes around the charging blade (16) for each rotation and is sufficiently precharged, while circulating until the toner scraping mechanism (18) is turned on.

In the above state, the original image is scanned to form an electrostatic latent image on the surface of the photosensitive drum (6), and the electrostatic latent image moves to a portion facing the developing sleeve (4). Then, the developer is developed by being rubbed by the magnetic brush of the developer on the developing sleeve (4).

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

Hereinafter, the toner supply operation will be described with reference to the flowchart shown in FIG. 4 and the time chart shown in FIG.

In step (S101), it is determined whether or not the main motor is turned on. If it is turned on, the toner supply roller (15) is turned on in step (S102). As a result, as described above, a charged toner layer having a constant thickness is formed on the toner supply roller (15). If the main motor is off, the solenoid (25) is turned off in step (S105) and the routine returns.

Next, in step (S103), it is determined whether or not the toner supply signal is on, that is, whether or not the toner density sensor (9) has detected a low density. In S104), the solenoid (25) is turned on.

As a result, the frame (20) engaged with the solenoid (25) rotates in the direction of the arrow (d) in FIG. 2, and the tip of the scraping blade (22) comes into pressure contact with the toner supply roller (15). Accordingly, the charged toner layer having a constant thickness formed on the toner replenishing roller (15) is scraped off and replenished into the developing tank (3) as shown in FIG. At this time, since the toner on the toner replenishing roller (15) is charged and formed in a layer having a constant thickness, the toner is continuously replenished into the developing tank (3) at a constant rate with a good dispersion. .

The replenished toner is supplied onto the developing sleeve (4) by the bucket roller (5) as described above, and is conveyed to a portion facing the photosensitive drum (6) to be subjected to development. Since the toner is replenished with good dispersion, poor charging and poor dispersion on the developing sleeve (4) do not occur, and a beautiful image free from unevenness and fogging of the developer can be obtained.

When the toner is supplied and the toner density on the developing sleeve (4) increases, the toner density detection sensor (9)
Detects this, and issues a toner supply stop signal to the control device (19).

Then, since the toner supply signal is off in step (S103), the solenoid (25) is turned off in step (S105) and the routine returns. As a result, the frame (20) of the toner scraping mechanism (18) is pulled back in the direction of the arrow (d ') by the spring (26), and the tip of the scraping blade (22) is separated from the toner supply roller (15). Therefore,
The charged toner layer on the toner replenishing roller (15) is conveyed in the direction of the arrow (c) without being scraped off, and goes around while being pre-charged by the charging blade (16).

For this reason, as long as the main motor is driven and the toner replenishing roller (15) is rotating, even if a toner replenishment signal is issued later, there will be no charging failure or dispersion failure.

In the above-described embodiment, while the toner supply signal from the toner concentration sensor (9) is raised, the solenoid (25) is always turned on to supply the toner. Is passed through the charging blade (16) and is soon scraped off by the scraping blade (22), so that it is only charged by a single frictional contact with the charging blade (16), and the preliminary charging is insufficient. May be replenished as is.

Therefore, even if the toner replenishment signal from the toner density sensor (9) rises, the toner is charged by the charging blade (16).
It is also possible to turn on the solenoid (25) only when the toner has passed through at least two times to supply toner.

That is, as shown in FIGS. 6 and 7, it is determined in step (S201) whether or not the main motor is turned on. If so, the toner supply roller (15) is turned on in step (S202). I do. As a result, a charged toner layer having a constant thickness is formed on the toner supply roller (15). If the main motor is off, the solenoid (25) is turned off in step (S209) and the routine returns.

Next, in step (S203), it is determined whether the toner supply signal is on. If it is off, the solenoid (25) is turned off in step (S209) and the process returns. If it is on, step (S204) is performed. To determine whether the solenoid (25) is on. Here, if the solenoid (25) is off, it is determined in step (S205) whether or not the toner has passed the charging blade (16) two or more times. If so, the solenoid is determined in step (S206). Turn on (25), and return if it has not passed. As a result, even if the toner supply signal is on, the toner is charged by the charging blade (1
The solenoid (25) waits in the OFF state until it passes through (6) two or more times.

If the solenoid (25) is on in step (S204), it is determined in step (S207) whether or not one revolution of the toner supply roller (15) has been completed since the solenoid (25) was turned on. If completed, the solenoid (25) is turned off in step (S208), and if not completed, the routine returns. 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) two or more times and has been sufficiently pre-charged is scraped off.

In the above-described embodiment, the toner is mechanically scraped off by a toner scraping mechanism (18) including a scraping blade (22) and a solenoid (25) as the toner peeling means. As shown in FIG. 9, a conductive roller (28) is disposed below the toner supply roller (15) with a predetermined gap, and the conductive roller (28) is moved by a motor (27). At the same time, it is formed so as to be rotatable, and is formed so as to apply a reverse voltage to the toner, that is, a negative voltage (V) based on the toner replenishment signal. Alternatively, the toner may be electrostatically peeled off by the sex roller (28) and then scraped off by the scraping blade (29). 8 and 9 are the same as those of the embodiment shown in FIGS. 1 and 3 except for the toner peeling mechanism (18a), and thus the description thereof is omitted.

In the above-described embodiment, as the toner concentration detecting means, the toner concentration in the developing device is detected by a toner concentration sensor provided in the developing device, and the toner replenishment control is performed based on this detection signal. The image density sensor provided on the photosensitive drum side detects the image density of a predetermined latent image pattern formed on the photosensitive drum after development, as a toner density detecting means, based on this detection signal. To perform toner supply control.

(Effects of the Invention) As is apparent from the above description, according to the present invention, a charged toner layer having a constant thickness is formed on a toner supply roller by a charging blade, and based on a toner supply signal,
The control means turns on and off the toner peeling means to peel off and replenish the charged toner layer.

Therefore, even if the toner replenishment signal does not rise, the charged toner layer is always formed as long as the main motor is driven. There is no replenishment in the developing device, and there is an effect that a beautiful image free of toner scum, fog and unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device provided with a toner replenishing device according to the present invention, FIG. 2 is a sectional view showing a toner scraping mechanism,
FIG. 3 is a plan view of the developing device shown in FIG. 1, and FIGS.
6 is a flowchart and a time chart of a toner supply control routine, and FIGS. 6 and 7 are flowcharts of another embodiment of the toner supply control routine.
FIG. 8 is a sectional view of a developing device provided with a toner replenishing device according to another embodiment of the present invention, and FIG.
FIG. 3 is a plan view of the developing device shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Toner supply device, 2 ... Developing device, 9 ... Toner density sensor, 14 ... Toner hopper, 15 ... Toner supply roller, 16 ... Charging blade, 18 ... Toner scraping mechanism (toner peeling means) , 19 ... Control device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yasuyuki Hiromoto 2-30-30 Azuchicho, Higashi-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Camera Co., Ltd. (72) Tomoaki Yokoyama 2-chome Azuchi-cho, Higashi-ku, Osaka, Osaka 30 Osaka International Building Minolta Camera Co., Ltd. (72) Inventor Kunio Toda 2-30 Azuchicho, Higashi-ku, Osaka City, Osaka Prefecture Osaka International Building Minolta Camera Co., Ltd. (56) References JP-A-54-151840 (JP) A) Jiko 49-31158 (JP, Y1)

Claims (1)

(57) [Claims] 1. A toner replenishing device attached to a developing device for supplying and developing toner to a latent image formed on an electrostatic latent image carrier, comprising: a toner hopper for storing toner; and a toner hopper provided below the toner hopper. A toner replenishing roller that is provided to close the opening and is driven to rotate with the driving of the main motor of the developing device; and a toner replenishing roller that is provided in pressure contact with the toner replenishing roller to charge the toner conveyed on the toner replenishing roller with a constant thickness. A charging blade for forming a toner layer of the toner supply roller, a toner separation unit provided downstream of the charging blade in the rotation direction of the toner supply roller, and separating the toner layer on the toner supply roller to supply the toner layer to the developing device; And a control unit for performing on / off control of the toner peeling unit based on a signal from the detection unit.