JPH08179621A - Development device - Google Patents

Abstract

(57) [Summary] [Purpose] Stabilization of the brush pressure of the magnetic brush against the latent image carrier during development by preventing the magnetic brush pool from staying near the developer regulating member when the developer carrier is reversed. To achieve
Provided is a developing device capable of obtaining a good image. Constitution: When the developing sleeve 4 is rotated in the reverse direction, the doctor blade 61 is swung in the direction of arrow e in FIG.
It is provided in the casing 7 so as to be swingably supported by the support shaft 10 so as to have a wide interval with. Further, when the developing sleeve 4 rotates in the normal direction, the opening of the casing 7 serving as a swing restricting member that restricts swinging beyond the predetermined distance to the developing sleeve 4 to the downstream side in the rotation direction of the developing sleeve 4. It abuts the end 7a located.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer, and more specifically, a magnetic brush made of a developer carried on a surface of a developer carrying body is provided with a predetermined height or quantity. The present invention relates to a developing device provided with a developer regulating member that regulates the above.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus in which developing devices are juxtaposed in the vicinity of a latent image carrier having a latent image formed on the surface thereof, for example, as in the developing device disclosed in JP-A-2-23027, At the time of development, a magnetic brush is formed on the surface of the developer carrying member by the magnetic force generated by the magnetic field generating means, and the magnetic brush is supplied to the surface of the latent image carrying member after having a predetermined height or amount by the developer regulating member. There is known a developing device that visualizes a latent image.

As a developing device for forming a magnetic brush on the surface of the developing carrier as described above, for example, FIG.
Also, a developing device as shown in FIG. 16 is known. That is, in the developing device shown in FIGS. 15 and 16, the developing sleeve 4, which is a developing carrier, is moved forward by the drive source (not shown) in the rotational direction A of the photosensitive body 1, which is a latent image carrier, during development. It is designed to be rotationally driven in the direction of the arrow a which is the direction (hereinafter, the case of rotating in the direction of the arrow a is referred to as “forward rotation”), and a plurality of magnets 3 as magnetic field generating means are provided therein. It is placed in a non-rotating state. The magnet 3 includes a magnet 3a for drawing up the developer 9 from the developer accommodating portion 7c in the casing 7 as a developer accommodating member onto the developing sleeve 4, and the developer 9 from the developing sleeve 4 onto the developer accommodating portion 7c. The magnet 3b is returned to the inside, and a low magnetic force portion 8 is formed between the magnets 3a and 3b and is low enough to prevent the developer 9 from being carried on the developing sleeve 4.

At the time of development, the developer 9 composed of toner and carrier contained in the developer container 7c is
The paddle 5 as a developer carrying means carries the developer onto the developing sleeve 4, and the magnetic force of the magnet 3a carries the developer onto the developing sleeve 4 to form a magnetic brush on the developing sleeve 4. With the forward rotation of the developing sleeve 4, the magnetic brush is conveyed to a portion (hereinafter, referred to as a doctor gap) D between a developing blade 4 and a doctor blade 6 as a developer regulating member provided near the developing sleeve 4. By passing through the doctor gap D, the magnetic brush 9b is regulated to a predetermined height or amount and becomes the magnetic brush 9b. This magnetic brush 9b is provided on the developing sleeve 4 facing the photoconductor 1.
The latent image on the surface of the photoconductor 1 is visualized by being conveyed to an upper region (hereinafter referred to as a developing region) G. The magnetic brush remaining on the developing sleeve 4 after being conveyed to the developing area G is magnetized by the magnet 3a and the magnet 3b as the developing sleeve 4 rotates normally.
Before being conveyed to the low magnetic force section 8 between the magnet 3b and the magnet 3b, it is returned to the developer accommodating portion 7c in the casing 7 and is stirred by the paddle 5 in the casing 7, and then again as the developer 9 by the magnet 3a. It is carried on the developing sleeve 4. In this way, the developer 9 circulates between the developer accommodating portion 7c in the casing 7 and the developing sleeve 4.

In the case of a color copying machine in which a plurality of such developing devices are arranged side by side around a latent image carrier such as a photoconductor, when developing by one developing device, another developing device is used. It is necessary to carry out the cutting of the developing sleeve. This is because unless the developing sleeve is cut off from the other developing sleeves, the magnetic images on the other developing sleeve other than the developing sleeve that is performing the development will be disturbed by the developed image of a certain color. This is because the colors may be mixed or mixed.

Therefore, for example, FIG. 15 and FIG.
When the developing sleeve 4 rotates in the direction of the arrow a in FIG.
The developer 9 is carried while being drawn up by the magnetic force of the magnet 3a. Then, when rotating in the direction of the arrow b in FIG. 16, that is, when reversing, the spike cutting is performed. At the time of this reverse rotation, the developer 9 drawn up onto the developing sleeve 4 by the magnet 3a is conveyed to the low magnetic force portion 8 immediately after being drawn up, and the centrifugal force and the self-weight due to the rotation of the developing sleeve 4 cause the developing sleeve 4 to move into the casing 7. The developing sleeve 4 does not carry the developer 9, and the developing area G and the surface portion of the developing sleeve are in the state of the spikes.

[0007]

However, the developer 9 circulating between the developer accommodating portion 7c and the developing sleeve 4 at the time of development as described above remains on the developing sleeve 4 after passing through the developing area G. Even if the magnetic brush is conveyed from the magnet 3b to the low magnetic force portion 8 with the positive rotation of the developing sleeve 4, the magnetic brush is attracted by the magnet 3b and the developer is accommodated depending on the centrifugal force or the self-weight due to the rotation of the developing sleeve 4. The developer pool 9a may be formed in the vicinity of the low magnetic force portion 8 without returning to the portion 7c.

When the developer 9 is cut off, that is, when the developing sleeve 4 rotates in the reverse direction, the developer pool 9a passes through the developing area G and is conveyed to the doctor gap D when the developing sleeve 4 rotates in the reverse direction. Then, it tries to pass through the doctor gap D, but at the time of development, it cannot pass because the amount per unit area is larger than that of the magnetic brush 9b after being regulated by the doctor blade 6, so that the developing sleeve 4 rotates in the rotation direction. The developer stays near the side surface of the doctor blade 6 on the upstream side, and is rotated by the doctor blade 6 by further rotation of the developing sleeve 4 to become a developer pool 9c having a larger amount per unit area than the developer pool 9a.

Therefore, when the developer pool 9c having a large amount per unit area is conveyed to the developing area G, the developer pool 9 is formed.
In the developing area G of c, the spike pressure on the photoconductor 1 is increased,
When the developer pool 9c having a high peak pressure comes into contact with the photoconductor 1 in the development area G during development, fluctuations in the rotation speed of the photoconductor 1 may occur, which may cause abnormal images such as color misregistration and image distortion. There was a problem. Depending on the setting of the distance between the developing sleeve 4 and the photoconductor 1 in the developing area G, when the developer reservoir 9a passes through the developing region G when the developing sleeve 4 is rotated in the reverse direction, the developer reservoir 9a may be removed. The rotation pressure of the photoconductor 1 may be changed by the spike pressure, and an abnormal image such as color misregistration or image distortion may occur.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the accumulation of the developer pool in the vicinity of the developer regulating member when the developer carrying member is reversed. It is an object of the present invention to provide a developing device capable of stabilizing a bristle pressure of a magnetic brush on a latent image carrier at the time of development and obtaining a good image.

[0011]

In order to achieve the above object, the invention of claim 1 has an opening facing a latent image carrier having a latent image formed on the surface thereof, and a developer inside. A developer accommodating member for accommodating and a developer carrying member which is disposed near the opening so as to face the latent image carrying member and supplies a magnetic brush made of the developer to the latent image carrying member and which can be rotated in the forward and reverse directions. And a developer regulating member which is arranged so as to face the developer carrying member and regulates the magnetic brush on the surface of the developer carrying body to a predetermined height or amount, and a desired magnetic field on the surface of the developer carrying body. Magnetic field generating means for forming a magnetic brush on the surface of the developer carrier by the magnetic force of the magnetic field generating means at the time of development and reversely rotating the developer carrier at the time of non-development. In a developing device for cutting off the spikes, when the developer carrying member is rotated in the reverse direction, It is characterized in that the distance between the image-carrying member and the developer regulating member is widened.

According to a second aspect of the present invention, in the developing device according to the first aspect, when the developer carrying member is rotated in a reverse direction, the developer bearing member is separated from the developer carrying member by the brush pressure received from the magnetic brush on the developer carrying member. The developer regulating member is swingably provided so as to widen the interval.

According to a third aspect of the present invention, in the developing device according to the first aspect, the developer carrying member is so arranged that a space between the developer carrying member and the developer regulating member is widened when the developer carrying member is rotated in a reverse direction. It is characterized in that the body is swingably provided.

According to a fourth aspect of the present invention, there is provided a developer accommodating member having an opening facing a latent image carrier having a latent image formed on the surface thereof and accommodating a developer therein, and the latent image near the opening. A developer carrying member which is arranged so as to face the carrier and which is capable of rotating forward and backward, supplying a magnetic brush made of the developer to the latent image carrier, and which is arranged so as to face the developer carrier, A first developer regulating member that regulates the magnetic brush on the surface of the developer bearing member to a predetermined height or amount, and a magnetic field generating unit that forms a desired magnetic field on the surface of the developer bearing member are provided. The developer carrying member is rotated in the forward direction so that a magnetic brush is carried on the surface of the developer carrying member by the magnetic force of the magnetic field generating means, and the developer carrying member is rotated in the reverse direction during non-development to remove the spikes of the magnetic brush. In the developing device for carrying out the A second developer regulating member for regulating the magnetic brush on the developer carrying member to a predetermined height or amount when the holding member is rotated in the reverse direction is provided, and when the developer bearing member is rotated in the reverse direction, It is characterized in that the distance between the developer carrying member and the second developer regulating member is narrower than that during normal rotation of the developer carrying member.

According to a fifth aspect of the present invention, in the developing device according to the fourth aspect, when the developer carrying member is rotated in the reverse direction, the brush pressure received from the magnetic brush on the developer carrying member causes the developer carrying member to be separated from the developer carrying member. It is characterized in that the second developer regulating member is swingably provided so as to narrow the interval.

According to a sixth aspect of the present invention, in the developing device according to the fourth aspect, the distance between the developer carrying member and the second developer regulating member is narrowed when the developer carrying member is rotated in the reverse direction. The developer carrying member is swingably provided.

[0017]

According to the present invention, when the developer carrier is reversed, that is, when the magnetic brush is cut off, the distance between the developer carrier and the developer regulating member, that is, the doctor gap is increased. Therefore, the developer reservoir made of the magnetic brush remaining on the developer carrying member without being returned to the developer accommodating member after being conveyed to the developing area along with the normal rotation of the developer carrying member at the time of development is After the developer carrying member is rotated in the reverse direction, the developer carrying member is conveyed to the developing area, and then is conveyed into the developer accommodating member through the doctor gap having a wide interval.

In particular, in the invention of claim 2, at the time of the cutting of the spikes, the developer regulating member swings due to the spike pressure applied from the magnetic brush on the developer carrying member so that the developer regulating member and the developer carrying member are carried. The distance from the body widens.

Further, in the invention of claim 3, at the time of the cutting of the ear, the developer carrier swings to widen the space between the developer regulating member and the developer carrier.

In a fourth aspect of the present invention, the second developer regulating member for regulating the magnetic brush on the developer bearing member to a predetermined height or amount when the developer bearing member is rotated in the reverse direction is a developing member. When the agent carrier is rotated in the reverse direction, that is, when the magnetic brush is cut off, the space between the developer carrier and the developer carrier is narrower than that during the normal rotation of the developer carrier. Therefore, the developer reservoir made up of the magnetic brush remaining on the developer carrying member without being returned to the developer accommodating member after being conveyed to the developing area along with the normal rotation of the developer carrying member during development is When the body is reversed, it passes between the narrowed developer carrying member and the second developer regulating member, is regulated to a predetermined height or amount, and is conveyed to the developing area. It passes through between the body and the first developer regulating member and is accommodated in the developer accommodating member.

In particular, in the invention of claim 5, at the time of the cutting of the spikes, the spike of the brush applied from the magnetic brush on the developer carrying member causes the second developer regulating member to swing, whereby the second developer is swung. The distance between the regulation member and the developer carrying member becomes narrow.

Further, in the invention of claim 6, at the time of the cutting of the ear, the developer carrier swings to widen the interval between the second developer regulating member and the developer carrier.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a developing device used in a color electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a front view showing the outline of a copying machine to which the developing device according to this embodiment is applied,
FIG. 2 is an explanatory diagram showing a state of the developing device during development, and FIG. 3 is an explanatory diagram showing a state of the developing device during cutting of a brush. FIG.
The copying machine of No. 4 visualizes and develops each electrostatic latent image corresponding to four colors of black B, cyan C, magenta M, and yellow Y formed on the photoconductor 1 as a latent image carrier 4 It is equipped with a developing device. Since these four developing devices have the same configuration and operation, the developing device 20B corresponding to black B will be described below.

The developing device 20B is the same as that shown in FIGS.
Similarly to the developing device shown in FIG. 6, the developing sleeve 4 as a developing carrier is driven by a drive source (not shown) in the forward direction with respect to the rotation direction A of the photoconductor 1 which is a latent image carrier during development. It is designed to rotate normally in the direction of arrow a,
A plurality of magnets 3 as magnetic field generating means are arranged in the inside thereof in a non-rotating state. The magnet 3 includes a magnet 3a for pumping the developer 9 arranged in a casing 7 as a developer accommodating member from the casing 7 onto the developing sleeve 4.
A magnet 3b for returning the developer 9 from above the developing sleeve 4 into the casing 7 is provided. Between the magnets 3a and 3b, a low magnetic force portion 8 having a low magnetic force so that the developer 9 is not carried on the developing sleeve 4 is provided. Has become.

The developer 9 composed of toner and carrier contained in the developer accommodating portion 7c is conveyed onto the developing sleeve 4 by the stirring paddle 5 as a developer conveying means and developed by the magnetic force of the magnet 3a. Carried on the sleeve 4 to form a magnetic brush on the developing sleeve 4. This magnetic brush moves with the forward rotation of the developing sleeve 4,
The magnetic brush 9b is conveyed between the doctor blade 6 as a developer regulating member provided near the developing sleeve 4 and the developing sleeve 4, that is, the doctor gap D and regulated to a predetermined height or amount to form the magnetic brush 9b. The magnetic brush 9b is conveyed to the developing area G on the developing sleeve 4 facing the photoconductor 1 to visualize the latent image on the surface of the photoconductor 1. The magnetic brush remaining on the developing sleeve 4 after being conveyed to the developing area G is magnetized before being conveyed to the low magnetic force portion 8 between the magnet 3a and the magnet 3b as the developing sleeve 4 rotates in the normal direction. It is returned to the developer accommodating portion 7c in the casing 7 by 3b, stirred by the stirring paddle 5 in the casing 7, and then again carried as the developer 9 on the developing sleeve 4 by the magnet 3a. In this way, the developer 9
Circulates between the developer container 7c and the developing sleeve 4. Although the two-component magnetic developer including the toner and the carrier is used as the developer 9 in this embodiment, it may be a one-component magnetic developer.

However, in such a developing device 20B, as described above, when the developing sleeve 4 is rotated in the reverse direction, it is located near the side surface of the doctor blade 6 on the upstream side in the rotating direction of the developing sleeve 4 rather than the magnetic brush 9b. A developer pool 9c having a high ear pressure for 1 is formed. Then, the developer pool 9c having a high ear pressure is conveyed to the developing area G along with the normal rotation of the developing sleeve 4, which may cause fluctuations in the rotation speed of the photoconductor 1.

Therefore, in this embodiment, instead of the doctor blade 6, a doctor blade 61 is provided which can prevent the developer pool 9c from being formed in the vicinity of the side surface of the doctor blade when the developing sleeve is reversed.

As shown in FIG. 2, when the developing sleeve 4 is rotated in the reverse direction, the doctor blade 61 swings in the direction of arrow e in FIG. It is provided in the casing 7 so as to be swingably supported by the support shaft 10 so as to widen the distance from the casing 4. Further, when the developing sleeve 4 rotates in the normal direction, the casing 7 has a function as a swinging restricting member that restricts the developing sleeve 4 from swinging to a downstream side in the rotation direction of the developing sleeve 4 over a predetermined distance. It comes into contact with the casing end 7a located near the opening.

In the present embodiment, at the time of cutting the head, that is, when the developing sleeve 4 is rotated in the reverse direction, as described above, the developer pool 9a formed during the development passes through the developing area G when the developing sleeve 4 is rotated in the reverse direction. Then, when it is transported to the doctor gap D, as shown in FIG.
Is swung to the downstream side in the rotational direction of the developing sleeve 4 due to the brush pressure received from the developer pool 9a, and the doctor gap D is widened. Then, the magnetic brush 9 a passes through the widened doctor gap D and is conveyed into the casing 7, and is returned to the developer accommodating portion 7 c in the casing 7 by the low magnetic force portion 8. During development, the doctor blade 61 is
As shown in FIG. 7, the doctor gap D is brought into contact with the casing end portion 7a and its swing is restricted, so that the doctor gap D becomes a predetermined distance, and when the magnetic brush formed on the developing sleeve 4 passes through the doctor gap D. The magnetic brush 9b, which is regulated to have a predetermined height or amount and has a predetermined amount per unit area, is conveyed to the developing area G. As a result, in the photoconductor 1, the developer pool 9a does not stay near the side surface of the doctor blade 61 on the upstream side in the rotation direction of the developing sleeve 4 at the time of cutting of the ear to form the developer pool 9c. The fluctuation of the rotation speed due to the pool 9a does not occur, and an abnormal image such as color shift or image distortion does not occur.

4 and 5 show a modification of the doctor blade. In this example, the doctor blade 62
Has a front end inserted into a hole 7d provided in the vicinity of the opening of the casing 7, and a rear end swingably supported by a support shaft 16. Then, the long hole P formed at the rear end portion
A pin fixed to the plunger 13a of the solenoid 13 as the swing drive means is inserted therein, and the rear end portion and the plunger 13a are connected.

The solenoid 13 moves the plunger 13a into the main body by excitation or demagnetization, and supports the doctor blade 62 connected via a pin to the support shaft 16
Is used as a fulcrum to swing the direction of the arrow f in the drawing, that is, to the upstream side in the rotational direction of the developing sleeve 4 at the time of cutting, to widen the doctor gap D. In this example, the plunger 13a is excited to cause the solenoid 13 to move. It moves inside the body. The solenoid 13 has a spring 15 whose one end is connected to the doctor blade 62.
Connected with. This spring 15 is the solenoid 1
3 does not hinder the swinging of the doctor gap D in the direction to widen it, and the demagnetization of the solenoid 13 urges the doctor blade 62 toward the casing 7 to keep the doctor gap D at a predetermined interval. It has an elastic force to the extent possible.

FIG. 6 is a timing chart of the developing sleeve 4 and the solenoid 13.
6 is controlled to be excited while the developing sleeve 4 is rotating in the reverse direction, that is, while the spike cutting is performed.

According to this example, at the time of brush cutting, that is, when the developing sleeve 4 is rotated in the reverse direction, as described above, the developer pool 9a formed during the development passes through the developing area G as the developing sleeve 4 is rotated in the reverse direction. Then, when the doctor blade 62 is conveyed to the doctor gap D, the doctor blade 62 swings in the direction of the arrow f in the figure by the excitation of the solenoid 13 to widen the doctor gap D, as shown in FIG. Then, the developer pool 9a passes through the widened doctor gap D and is conveyed into the casing 7, where the low magnetic force portion 8 causes the casing 7 to move.
It is returned to the developer accommodating portion 7c therein. Then, at the time of development, the doctor blade 62 is urged in the direction of the casing 7 by the elastic force of the spring 15 due to the demagnetization of the solenoid 13 and comes into contact with the outer wall of the casing 7 having a function as a swing restriction member. The tip of the doctor blade 62 is prevented from colliding with the developing sleeve 4, and the doctor gap D becomes a predetermined distance. And
The magnetic brush formed on the developing sleeve 4 is regulated to a predetermined height or amount when passing through the doctor gap D, and becomes a magnetic brush 9b having a predetermined amount per unit area in the developing area G. Be transported. As a result, the photoreceptor 1 has the developing sleeve 4 when the developer pool 9a is cut off.
Since the developer pool 9c does not stay in the vicinity of the side plate of the doctor blade 62 on the upstream side in the rotation direction of the above, the fluctuation of the rotation speed due to the developer pool 9a does not occur, and the color misregistration and the image distortion are caused. The abnormal image of does not occur.

Next, another embodiment of the doctor blade capable of preventing the developer pool 9c from being formed in the vicinity of the side surface of the doctor blade when the developing sleeve is reversed will be described. Note that the description in the above-described embodiment is applied to points that are not particularly described.

In the developing device 20B shown in FIGS. 7 and 8, when the developing sleeve 4 is rotated in the normal direction, the doctor blade 6 as the first developer regulating member for regulating the magnetic brush to a predetermined height or amount is provided in the casing. 7 is formed in the vicinity of the opening, and a doctor gap D is formed between the doctor blade 6 and the developing sleeve 4. Further, when the developing sleeve 4 is rotated in the reverse direction, a doctor blade 63 as a second developer regulating member that regulates the developer pool 9a before being conveyed to the developing area G to a predetermined height or amount is provided in the developing sleeve 4. A doctor gap d is formed between the doctor blade 63 and the developing sleeve 4 in the vicinity of the opening of the casing 7 facing the surface that rises during reverse rotation.

The doctor blade 63 as the second developer regulating member is swingably provided by a support shaft 14 in a hole 7e provided in the vicinity of the opening of the casing 7, and one end 63a of the doctor blade 63 is provided in the casing 7. It is located inside and the other end 63 b is located outside the casing 7. One end 63a
Has an edge portion inclined so that the doctor gap d is swung in a direction in which the doctor gap d is narrowed, that is, in a direction approaching the developing sleeve 4 by the brush pressure received from the developer pool 9a when the developing sleeve 4 is rotated in reverse, Also, the other end 63b
Is a spring 1 whose one end is connected to the casing 7.
It is connected to 2. Further, the doctor gap d when narrowed is set to be narrower than the doctor gap D formed by the doctor blade 6 and the developing sleeve 4 as the first developer regulating member.

At the time of development, that is, when the developing sleeve 4 rotates in the forward direction, the spring 12 has a direction in which the one end 63a is separated from the developing sleeve 4 by the brush pressure received from the developer pool 9a on the developing sleeve 4, that is, the doctor gap d. Does not hinder swinging in the spreading direction, and
When the developing sleeve 4 temporarily stops its rotation when the rotation direction is switched, the other end 63b is pushed down in the direction of an arrow g in the drawing to expand and contract so that the one end 63a enters the developer reservoir 9a. It has power.

Then, as shown in FIG. 7, the developing sleeve 4
During normal rotation, that is, during development, one end 63a of the doctor blade 63 swings in the direction away from the developing sleeve 4 by the brush pressure received from the developer pool 9a on the developing sleeve 4, and the doctor gap d becomes wider. At this time, the other end 63
b moves against the elastic force of the spring 12, and the spring 12 is compressed. When the rotation of the developing sleeve 4 is stopped at the time of cutting the head, the other end 63b moves in the direction of arrow g in FIG. 8 due to the elastic force of the spring.
The doctor gap d is narrowed by the spike pressure of the developer pool 9a that is received when the one end 63a swings toward the developing sleeve 4 and enters the magnetic sleeve pool 9a and the developing sleeve 4 rotates in the reverse direction. At this time, the doctor blade 63 is prevented from colliding with the surface of the developing sleeve 4 by swinging the one end 63a by contacting a part of the doctor blade 63 with the peripheral edge Q having a function as a swing restricting member of the hole 7e. To be done.

In the example shown in FIGS. 7 and 8, as described above, the developer pool 9a formed at the time of development is conveyed to the narrowed doctor gap d at the time of cutting, and passes through this doctor gap d. After being conveyed to the developing area G by being regulated to a predetermined height or amount, the developer accommodating portion in the casing 7 passes through the doctor gap D that is wider than the doctor gap d. Returned to 7c. For this reason, it is possible to prevent the developer pool 9a from accumulating near the side surface of the doctor blade 6 on the upstream side in the rotation direction of the developing sleeve 4 at the time of cutting of the ear to form the developer pool 9c.

At the time of development, the magnetic brush formed on the developing sleeve 4 is regulated to a predetermined height or amount when passing through the doctor gap D, and has a predetermined amount per unit area. 9b and conveyed to the developing area G. As a result, in the photoconductor 1, since the developer image developer pool is not formed near the side surface of the doctor blade 6, the fluctuation of the rotation speed due to the developer pool 9a does not occur, and the abnormal image such as the color shift or the image distortion is generated. Does not occur.

Further, in the developing device 20B of the present embodiment, the doctor gap d is set to be narrower than the distance between the developing sleeve 4 and the photosensitive member 1 in the developing area G, so that the developer pool 9a is developed. When the developer passes through the developing area G due to the reverse rotation of 4, the developer pool 9
The rotation speed of the photoconductor 1 is not changed by the ear pressure of a.

9 and 10 show a modification of the second doctor blade. In this example, the second doctor blade 64 has a front end 64 a inserted into a hole 7 g provided in the vicinity of the opening of the casing 7, and a rear end 64 b is swingably supported by the support shaft 18. Then, the pin fixed to the plunger 13a of the solenoid 13 as the swing drive means is inserted into the elongated hole P formed in the rear end portion 64b to connect the rear end portion 64b and the plunger 13a. Has been done. Further, in the vicinity of the tip end portion 64a, in order to prevent the tip end portion 64a from rocking until it collides with the surface of the developing sleeve 4, a rocking regulation for contacting the peripheral edge of the hole portion 7g to regulate the rocking. The convex portion 64c having a function as a member is provided.

The solenoid 13 moves the plunger 13a into the main body by excitation or demagnetization, and swings the doctor blade 64 connected through the pin P in the direction of arrow h in the figure with the support shaft 18 as a fulcrum. To narrow the doctor gap d, and in this example, the plunger 13a moves into the body of the solenoid 13 by excitation. The solenoid 13 is also connected to a spring 19 whose one end is connected to the doctor blade 64. This spring 19 is the solenoid 13
It has an elastic force that does not prevent the doctor gap d from swinging in the direction in which the doctor gap d is narrowed by excitation and is swingable in the direction in which the doctor gap d is widened by demagnetizing the solenoid 13. .

FIG. 11 is a timing chart of the developing sleeve 4 and the solenoid 13.
11 is controlled so as to be excited while the developing sleeve 4 is rotating in the reverse direction, that is, while the spike cutting is being performed.

In the example shown in FIGS. 9 and 10, as described above, the developer pool 9a formed at the time of development is conveyed to the doctor gap d narrowed by the excitation of the solenoid 13 at the time of cutting the head, and the doctor gap d is formed. After being regulated to a predetermined height or amount by the blade 64 and conveyed to the developing area G, the developer accommodating portion in the casing 7 passes through the doctor gap D that is wider than the doctor gap d. Returned to 7c. Therefore, it is possible to prevent the developer pool 9a from accumulating in the vicinity of the side surface of the doctor blade 6 on the upstream side in the rotation direction of the developing sleeve 4 at the time of ear cutting to form the developer pool 9c.

At the time of development, the magnetic brush formed on the developing sleeve 4 is regulated to have a predetermined height or amount when passing through the doctor gap D, and has a predetermined amount per unit area. 9b and conveyed to the developing area G. As a result, in the photoconductor 1, the developer pool 9a stays in the vicinity of the side surface of the doctor blade 6 on the upstream side in the rotation direction of the developing sleeve 4 at the time of cutting of the spikes, and the developer pool 9a.
Since c is not formed, fluctuations in the rotation speed due to the developer pool 9a do not occur, and abnormal images such as color misregistration and image distortion do not occur.

In the developing device 20B as described above, the doctor gap d is set to be narrower than the distance between the developing sleeve 4 and the photoconductor 1 in the developing area G, so that the developer pool 9a is developed. When the toner passes through the developing area G due to the reverse rotation of No. 4, the rotation speed of the photoconductor 1 is not changed by the brush pressure of the developer pool 9a.

Here, in each of the above-described embodiments, in order to prevent the developer pool 9c from being formed when the developing sleeve is reversed, the doctor blade for regulating the magnetic brush to a predetermined height or amount is shaken. Although it is an example of movably provided, instead of oscillating the doctor blade,
It is also possible to prevent the developer pool 9c from being formed by swingably providing the developing sleeve 4 as the developer carrying member. Hereinafter, an example of the developing device 20B in which the developing sleeve 4 is swingably provided will be described. Note that the description in each of the above-described embodiments is applied to points that are not particularly described.

The developing device 20B of this embodiment is provided with an arm 30 as a supporting member for rotatably supporting the developing sleeve 4 via the rotary shaft 22. As shown in FIG. 12, one end 30a of this arm 30 has a photosensitive member 1
The upper support shaft 1a is rotatably connected to the other end, and the other end 30b rotatably supports the developing sleeve 4.
The developing sleeve 4 is arranged between a doctor blade 6 as a first developer regulating member provided near the opening of the casing 7 and a casing collar portion 7d having a function as a second developer regulating member. There is.

Further, the arm 30 has a long hole P at a substantially central portion in the longitudinal direction thereof, and is connected to the plunger 13a of the solenoid 13 through the long hole P, and the vicinity of the long hole P. Thus, one end is connected to the spring 31 attached to the side wall of the device. The spring 31 does not prevent the developing sleeve 4 from swinging in a direction in which the doctor gap D formed by the developing sleeve 4 and the doctor blade 6 becomes narrower due to demagnetization of the solenoid 13, and the spring 31 does not move. It has an elastic force that does not prevent the developing sleeve 4 from swinging in the direction in which the doctor gap d formed by the developing sleeve 4 and the casing flange portion 7d becomes narrower due to the excitation.

Further, as shown in FIG. 13, the rotary shaft 22 rotatably supporting the developing sleeve 4 on the arm 30 has its both ends provided on both side plates 21 of the developing device 20B. The holes 23 are respectively inserted. The elongated hole 23 has a function as a rocking restricting member for restricting the rocking of the developing sleeve 4 due to the demagnetization or excitation of the solenoid 13, and the demagnetization of the solenoid 13 causes the developing sleeve 4 to move to the doctor blade 6. When approaching, that is, when swinging in the direction of narrowing the doctor gap d, the rotary shaft 22 contacts the upper end portion 23a, thereby preventing the developing sleeve 4 from colliding with the doctor blade 6 and developing the same. The sleeve 4 is positioned with respect to the doctor blade 6. Further, when the developing sleeve 4 approaches the casing flange portion 7d due to the excitation of the solenoid 13, that is, when the developing sleeve 4 swings in the direction of narrowing the doctor gap D, the rotary shaft 22 comes into contact with the lower end portion 23b. The developing sleeve 4 is prevented from colliding with the collar portion 7d and positioned with respect to the collar portion 7d.

In this embodiment, the solenoid 13 is demagnetized during development, that is, when the developing sleeve 4 rotates forward, and the developing sleeve 4 is positioned at the position shown by the solid line in FIG. However, when passing through the doctor gap D, it is regulated to a predetermined height or amount. The regulated magnetic brush is conveyed to the developing area G along with the rotation of the developing sleeve 4, and is then conveyed to the aforementioned low magnetic force portion 8 (not shown) to form the developer reservoir 9a as described above. To be done.

Then, at the time of cutting the edges, that is, the developing sleeve 4
At the time of the reverse rotation, the solenoid 13 is excited, and the developing sleeve 4 swings in the direction of narrowing the gap with the casing collar portion 7d and is positioned at the position shown by the broken line in the figure. With this swing, the doctor gap D becomes wider than during development. The developer pool 9a (not shown) is
After passing through the narrowed doctor gap d, regulated to a predetermined height or amount, and conveyed to the developing area G, the doctor gap D wider than the doctor gap d is passed and the casing 7 It is returned to the developer accommodating portion 7c therein. Therefore, it is possible to prevent the developer pool 9a from accumulating in the vicinity of the side surface of the doctor blade 6 on the upstream side in the rotation direction of the developing sleeve 4 at the time of ear cutting to form the developer pool 9c.

At the time of development, the magnetic brush formed on the developing sleeve 4 is regulated to have a predetermined height or amount when passing through the doctor gap D, and has a predetermined amount per unit area. 9b and conveyed to the developing area G. As a result, in the photoconductor 1, the developer pool 9a stays in the vicinity of the side surface of the doctor blade 6 on the upstream side in the rotation direction of the developing sleeve 4 at the time of cutting of the spikes, and the developer pool 9a.
Since c is not formed, fluctuations in the rotation speed due to the developer pool 9a do not occur, and abnormal images such as color misregistration and image distortion do not occur.

In the developing device 20B as described above, the doctor gap d is set to be narrower than the distance between the developing sleeve 4 and the photoconductor 1 in the developing area G, so that the developer pool 9a is developed. When the toner passes through the developing area G due to the reverse rotation of No. 4, the rotation speed of the photoconductor 1 is not changed by the brush pressure of the developer pool 9a.

In the present embodiment, the swinging of the developing sleeve 4 may be performed by changing only the interval of the doctor gap d without changing the interval of the doctor gap D at the time of development, that is, by narrowing the interval. . In this case, for example, the rotary shaft 2 has a circular arc centered on the doctor blade 6 and having a radius of a distance between the tip of the doctor blade 6 and the center of the rotary shaft 22 supporting the developing sleeve 4.
The developing sleeve 4 may be swung so that the central portion of 2 moves. Further, the swinging of the developing sleeve 4 can be performed so as to change only the interval of the doctor gap D, that is, to widen it, without changing the interval of the doctor gap d. In this case, for example, the center of the rotary shaft 22 is on an arc whose radius is the distance between the casing flange 7d and the center of the rotary shaft 22 that supports the developing sleeve 4. The developing sleeve 4 may be swung so that the parts move.

The embodiment in which the present invention is applied to a color electrophotographic copying machine in which a plurality of photoconductors, which are latent image carriers, are arranged around the photoconductor has been described above. It is also applicable to an image forming apparatus arranged in the periphery, and an image in which a plurality of developing devices are rotatably arranged around the photosensitive member and the developing devices are rotated to sequentially develop latent images on the photosensitive member. It can also be applied to a forming device.

[0058]

According to the invention of claim 1, when the developer carrying member is reversed, that is, when the developer is cut off, it passes between the developer carrying member having the wider developer pool and the developer regulating member. Since the developer is carried into the developer accommodating member, the developer pool does not stay near the developer regulating member when the developer carrying member is reversed. Therefore, as in the conventional case, the developer pool accumulated near the developer regulating member is conveyed to the developing area where the developer carrying member and the latent image carrying member face each other during forward rotation of the developer carrying member, that is, during development. Therefore, the magnetic brush has a constant brush pressure on the latent image carrier at the time of development, and image defects such as color misregistration and image distortion do not occur, and an image can be improved.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the magnetic brush on the developer carrying member can prevent the accumulation of the developer pool in the vicinity of the developer regulating member at the time of cutting the head. There is an effect that it can be achieved with a simple configuration in which the developer regulating member is swingably provided so that the gap with the developer carrying member is widened by the brush pressure received from the developer controlling member.

According to the third aspect of the present invention, in addition to the effect of the first aspect, the developer carrier and the developer can be prevented from accumulating in the vicinity of the developer regulating member at the time of cutting the spikes. This can be performed by swingably providing the developer carrying member so that the space between the developer carrying member and the regulating member is widened.

According to the invention of claim 4, the developer pool passes between the narrowed developer carrying member and the second developer regulating member when the developer carrying member is reversed, that is, when the developer is cut off. After that, since it passes through between the developer carrying member and the first developer regulating member and is conveyed into the developer accommodating member, when the developer carrying member is reversed, the developer pool near the developer regulating member. No retention occurs. Therefore, as in the conventional case, the developer pool accumulated near the developer regulating member is conveyed to the developing area where the developer carrying body and the latent image carrying body face each other at the time of normal rotation of the developer carrying body, that is, at the time of development. Therefore, the magnetic brush has a constant ear pressure on the latent image bearing member during development, and image defects such as color misregistration and image distortion do not occur, and the image can be improved. Further, by setting the interval between the developer carrying member and the second developer restricting member to be narrower than the interval between the developer carrying member and the latent image carrying member, the developer can be rotated when the developer carrying member rotates in the reverse direction. When the pool passes between the narrowed developer carrier and the developer regulating member, the pool is regulated to a height shorter than the distance between the developer carrier and the latent image carrier and conveyed to the developing area. As a result, the brush pressure on the latent image carrier of the magnetic brush that passes through the developing area at the time of cutting the edges becomes constant, and image defects such as color misregistration and image distortion do not occur, and it is possible to improve the image quality. There is.

According to the invention of claim 5, in addition to the effect of claim 4, the prevention of the conveyance of the developer pool to the developing area at the time of cutting the head is received from the magnetic brush on the developer carrier. There is an effect that it can be achieved with a simple configuration in which the second developer regulating member is swingably provided so that the gap with the developer carrying member is narrowed by the spike pressure.

According to the sixth aspect of the invention, in addition to the effect of the fourth aspect, it is possible to prevent the developer pool from being conveyed to the developing area at the time of cutting the edges of the developer by the developer carrier and the second developer. This can also be performed by swingably providing the developer carrying member so that the gap with the regulating member becomes narrow.

[Brief description of drawings]

FIG. 1 is a front view showing the outline of a copying machine to which a developing device according to this embodiment is applied.

FIG. 2 is an explanatory view showing a developing state of the developing device.

FIG. 3 is an explanatory view showing a state of the developing device at the time of cutting an ear.

FIG. 4 is an explanatory view showing a modified example of a doctor blade.

FIG. 5 is an explanatory view showing a state of the doctor blade when cutting a head.

FIG. 6 is a timing chart of driving a developing sleeve and a solenoid in the developing device.

FIG. 7 is an explanatory view showing a developing state of a developing device according to another embodiment.

FIG. 8 is an explanatory view showing a state of the developing device when cutting off the spikes.

FIG. 9 is an explanatory view showing a modification of the doctor blade.

FIG. 10 is an explanatory view showing a state of the doctor blade when cutting the head.

FIG. 11 is a timing chart of driving a developing sleeve and a solenoid in the developing device.

FIG. 12 is an explanatory view showing a main part of a developing device according to still another embodiment with a side plate removed.

FIG. 13 is an explanatory view showing a main part of the developing device with side plates attached.

FIG. 14 is a timing chart of driving a developing sleeve and a solenoid in the developing device.

FIG. 15 is an explanatory diagram showing a state of the conventional developing device during development.

FIG. 16 is an explanatory view showing a state of the developing device when cutting off the spikes.

[Explanation of symbols]

 1 Photosensitive Drum 1a Support Shaft 10 Support Shaft 13 Solenoid 15 Spring 16 Support Shaft 18 Support Shaft 20 Developing Device 21 Side Plate 22 Rotating Shaft 23 Long Hole 3 Magnet 30 Arm 4 Developing Sleeve 5 Stirring Paddle 61 Doctor Blade 62 Doctor Blade 63 Doctor Blade 64 Doctor Blade 7 Casing 7a Casing End 7c Developer Storage 8 Low Magnetic Field 9 Developer 9a Developer Reservoir 9c Developer Reservoir G Development Area

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroshi Ono 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Satoshi Hatori 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks Company Ricoh

Claims (6)

[Claims] 1. A developer accommodating member having an opening facing a latent image carrier having a latent image formed on its surface and accommodating a developer therein, and a developer accommodating member near the opening facing the latent image carrier. Is arranged as
A forward and reverse rotatable developer carrier for supplying a magnetic brush made of the developer to the latent image carrier, and a magnetic brush on the surface of the developer carrier, which is disposed so as to face the developer carrier, A developer regulating member for regulating the height or amount to a predetermined height and magnetic field generating means for forming a desired magnetic field on the surface of the developer carrying body are provided, and the magnetic force of the magnetic field generating means at the time of development causes the developer carrying body to move. A developing device in which a magnetic brush is carried on the surface, and the developer carrying member is reversely rotated at the time of non-development so as to cut off the magnetic brush, and when the developer carrying member is reversely rotated, A developing device characterized in that a space between the developer regulating member and the developer regulating member is widened. 2. The developer regulating member so that the gap between the developer carrying member and the developer carrying member is widened by the brush pressure received from the magnetic brush on the developer carrying member when the developer carrying member rotates in the reverse direction. 2. The developing device according to claim 1, wherein the developing device is swingable. 3. The developer carrying body is swingably provided so that a space between the developer carrying body and the developer regulating member is widened when the developer carrying body is rotated in a reverse direction. The developing device according to claim 1. 4. A developer accommodating member having an opening facing a latent image carrier on the surface of which a latent image is formed, and a developer accommodating member for accommodating a developer therein, and facing the latent image carrier near the opening. Is arranged as
A forward and reverse rotatable developer carrier for supplying a magnetic brush made of the developer to the latent image carrier, and a magnetic brush on the surface of the developer carrier, which is disposed so as to face the developer carrier, A first developer regulating member for regulating to a predetermined height or amount,
Magnetic field generating means for forming a desired magnetic field on the surface of the developer carrying member, the developer carrying member is rotated in the forward direction during development, and a magnetic brush is applied to the surface of the developer carrying member by the magnetic force of the magnetic field generating means. In a developing device for carrying and carrying out reverse rotation of the developer carrying member at the time of non-development to cut off the magnetic brush, the developer carrying member is arranged so as to face the developer carrying member, and when the developer carrying member is rotated in the reverse direction. A second developer regulating member for regulating the magnetic brush on the developer carrier to a predetermined height or amount,
Further, when the developer carrying member is rotated in the reverse direction, the distance between the developer carrying member and the second developer regulating member is narrower than that in the normal rotation of the developer carrying member. apparatus. 5. The second developer so that the gap between the developer carrying member and the developer carrying member is narrowed by the brush pressure received from the magnetic brush on the developer carrying member when the developer carrying member rotates in the reverse direction. The developing device according to claim 4, wherein the regulating member is provided so as to be swingable. 6. The developer carrying body is swingably provided so that a space between the developer carrying body and the second developer regulating member becomes narrow when the developer carrying body rotates in a reverse direction. The developing device according to claim 4, wherein: