JP2003263016A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of forming an image of appropriate density even just after the start of using the developing device, and to provide an image forming apparatus equipped with the developing device. <P>SOLUTION: Before the start of using, a boundary between a storage chamber 34a for storing toner and a developing chamber 34b in a developing cartridge 28 is closed with a shutter member 63 while keeping the toner packed in the developing chamber 34b, and the packed toner is pushed with a pushing member 68 toward a supply roller 33, then, the toner is packed with a density larger than the loose apparent density in the developing chamber 34b. Then, the toner is satisfactorily secured in the developing chamber 34b before the start of using, and then, the toner is satisfactorily supplied to the developing roller 31 even just after the start of using, consequently, the quantity of the toner carried by the developing roller 31 can be satisfactorily secured, and the image of the appropriate density can be formed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus such as a laser printer equipped with the developing device.

[0002]

2. Description of the Related Art In an image forming apparatus such as a laser printer, a developing cartridge containing toner is usually removably attached to the apparatus main body. The developing cartridge has a storage chamber for storing toner and a development chamber for developing toner, and an opening for communicating between the storage chamber and the developing chamber. Are formed. The storage chamber is rotatably provided with an agitator for transporting the stored toner from the opening to the developing chamber, and the developing chamber is provided with a supply roller, a developing roller and a layer thickness regulating blade. .

When the developing cartridge is mounted on the main body of the apparatus and each part is driven while the developing roller is opposed to the photosensitive drum, first, the agitator rotates.
The toner in the storage chamber is conveyed from the opening to the developing chamber, and the toner is supplied to the developing roller by the rotation of the supply roller. Then, as the developing roller rotates, the toner is separated between the layer thickness regulating blade and the developing roller. It enters and is carried on the surface of the developing roller as a thin layer having a constant thickness.

After that, when the toner carried on the surface of the developing roller faces the electrostatic latent image formed on the surface of the photosensitive drum as the developing roller rotates, the toner develops the electrostatic latent image. Form a visible image. Then, by transferring the visible image onto the paper, a predetermined image is formed on the paper.

[0005]

However, since the toner in the accommodating chamber is not conveyed to the developing chamber by the agitator before the use of the developing cartridge is started, for example, the laser in which the developing cartridge immediately after unpacking is mounted is installed. In the printer, in the developing cartridge, the amount of toner supplied from the supply roller to the developing roller is small. Therefore, the amount of toner carried per unit area on the surface of the developing roller is insufficient, resulting in a shortage of the absolute amount of toner and a consequent increase in the amount of electrostatic charge of toner per unit area. Density becomes low, and as a result, the density of the image formed on the paper decreases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a developing device capable of forming an image having an appropriate density even immediately after the use of the developing device is started, and An object of the present invention is to provide an image forming apparatus including such a developing device.

[0007]

To achieve the above object, the invention according to claim 1 is provided with a storage chamber for storing a developer, and a development chamber in which a developer carrier is provided. In a developing device in which an opening communicating between the storage chamber and the developing chamber is formed between the storage chamber and the developing chamber, in the opening before the use of the developing device is started, A shielding member that prohibits passage of the developer between the accommodation chamber and the developing chamber is provided, and the developing chamber is filled with the developer at a density higher than the loose apparent density. Is characterized by.

According to this structure, before the use of the developing device is started, the shielding member prohibits passage of the developer at the opening between the developing chamber and the developing chamber, and in that state, Since the developer is filled in the developing chamber at a density higher than the apparent density, the developer in the developing chamber is sufficiently secured at the start of use. Therefore, even immediately after the start of use, the developer is sufficiently supplied to the developer carrier, and as a result, the amount of the developer carried on the developer carrier can be sufficiently secured, and the developer having the appropriate concentration can be obtained. An image can be formed.

The invention according to claim 2 is provided with an accommodating chamber for accommodating a developer and a developing chamber in which a developer carrier is provided, and between the accommodating chamber and the developing chamber. In a developing device in which an opening communicating with the storage chamber and the developing chamber is formed, before the use of the developing device is started, the opening is provided between the storage chamber and the developing chamber. Is provided with a shielding member for prohibiting passage of the developer, and the developing chamber is filled with the developer at a rate of 2 g or more per cm in a width direction orthogonal to the height direction.

According to this structure, before the use of the developing device is started, the shielding member prohibits passage of the developer in the opening between the developing chamber and the developing chamber, and in that state, Since the developer is filled in the developing chamber in an amount of 2 g or more per 1 cm in the width direction orthogonal to the height direction, the developer in the developing chamber is sufficiently secured at the start of use, and due to the weight of the developer, The developer is sufficiently supplied to the developer carrier. Therefore, immediately after the start of use, the amount of the developer carried by the developer carrying member can be sufficiently secured, and an image having an appropriate density can be formed.

The invention described in claim 3 is the same as claim 1.
Alternatively, in the invention described in Item 2, the shielding member is provided so that the opening can be opened and closed.

According to this structure, before the use of the developing device is started, the opening is closed by the shielding member so that the developer can be well filled in the developing chamber, and the opening is opened at the start of use. Thus, the developer can be supplied from the storage chamber into the developing chamber through the opening. Therefore, with a simple configuration, it is possible to achieve the filling of the developer in the developing chamber before the start of use and the supply of the developer from the storage chamber into the developing chamber after the start of use.

The invention according to claim 4 is the same as claim 1.
In the invention described in any one of (1) to (3), a supply unit for supplying a developer to the developer carrying member is provided in the developing chamber so that the gravity of the developer in the developing chamber acts on the developing unit. It is characterized in that it is arranged below the developer in the room in the direction of gravity.

According to this structure, the supply means includes:
Since the weight of the developer acts, the supply unit can reliably hold the developer and supply it to the developer carrier by the pressure received from the developer. Therefore, it is possible to more reliably ensure the amount of the developer carrying member,
An image having an appropriate density can be formed.

The invention described in claim 5 is the same as claim 4
In the invention described in, in the developing chamber, a layer thickness regulating member for supporting the developer carrier in a thin layer of the developer is provided, the developer carrier, in the developing chamber, The layer thickness regulating member is disposed laterally in the direction of gravity of the developer in the developing chamber, and the layer thickness regulating member limits the gravity of the developer in the developing chamber from directly acting on the developer carrier. And the developer carrying member.

When the self-weight of the developer acts directly on the developer carrying member, the developer is carried directly on the developer carrying member without being charged between the supplying means and the developer carrying member. Charging becomes unstable.

However, according to such a structure, the layer thickness regulating member restricts the gravity of the developer in the developing chamber from directly acting on the developer carrying member, so that the developer carrying member has its own weight. Becomes difficult to act directly. Therefore, the developer carrying member is reliably supplied with the charged developer between the supply means and the developer carrying member, and stable charging of the developer can be ensured.

The invention described in claim 6 is the same as in claim 4
Alternatively, in the invention described in 5, the height of the developer in the developing chamber is 25 mm or more from the supply means before the use of the developing device is started.

According to this structure, since the height of the developer in the developing chamber is 25 mm or more from the supply means before the use of the developing device is started, the supply means is operated by the pressure received from the developer. Can be reliably held and supplied to the developer carrying member. Therefore, it is possible to more reliably ensure the amount of the developer carrying member,
An image having an appropriate density can be formed.

The invention described in claim 7 is the same as claim 1.
In the invention described in any one of (1) to (6), the developing chamber is provided with pressing means for pressing the developer toward the supply means.

According to this structure, if the developer in the developing chamber is pressed toward the supply means by the pressing means before the use of the developing device is started, the supply means is pressed at the start of use. Thus, it is possible to form a state in which the pressure from the developer is positively applied. Therefore, the supply amount of the developer to the developer carrier immediately after the start of use can be reliably ensured, so that the amount of the developer carrier can be more reliably ensured, and an image having an appropriate density can be obtained. Can be formed.

The invention described in claim 8 is the invention according to claim 7.
In the invention described in (1), the pressing means is configured to be able to release the pressing force.

With this structure, at the start of use of the developing device, the pressing force of the pressing means can be released to allow the developer to flow in the developing chamber. Therefore, after the start of use, the developer can be circulated in the developing chamber, and as a result, more favorable image formation can be achieved by stabilizing the charging.

The invention described in claim 9 is the same as claim 1.
In the invention described in any one of (1) to (5), a pressure release port for releasing the filling pressure of the developer is provided above the opening between the accommodation chamber and the development chamber. It has a feature.

According to this structure, if the pressure release port is closed before the use of the developing device is started, the developer is filled more closely in the developing chamber and the developer is carried at the start of use. The amount of developer carried on the body can be reliably ensured. After the start of use, the pressure release port is opened to make the filling of the developer in the developing chamber more sparse and to promote the flow of the developer, thereby stabilizing the charging and forming a better image. Can be achieved.

The tenth aspect of the invention is characterized in that, in the invention according to any one of the first to ninth aspects, the developer is substantially spherical toner.

If the developer is a square non-spherical toner, and the toner is densely packed in the developing chamber before the use of the developing device, it becomes difficult to flow after the use of the developing device. In some cases, the developer may be retained and printing defects may occur.

However, according to this structure, since the developer is a substantially spherical toner having a good fluidity, even if the developer is densely filled in the developing chamber before the use of the developing device, the developing device is well developed. After the start of use, the fluid can flow well, the charge can be stabilized, and good image formation can be achieved.

The invention described in claim 11 is characterized in that, in the invention described in any one of claims 4 to 10, the supply means is in contact with the developer carrying member.

According to this structure, since the supplying means is in contact with the developer carrying member, the developer supplied to the developer carrying body by the supplying means is present between these supplying means and the developer carrying body. Charged well. for that reason,
It is possible to make the developer carrier reliably carry the charged developer between the supply unit and the developer carrier.

The invention described in claim 12 is characterized in that, in the invention described in any one of claims 1 to 11, it is a non-magnetic one-component developing system.

In the case of the non-magnetic one-component developing method, it is necessary to carry a fixed amount of the stably charged developer on the developer carrying member. However, according to such a construction, before the start of use, the developing chamber is kept. Since it is possible to secure a sufficient amount of the developer, as a result, it is possible to secure a fixed amount of the developer carrying member and achieve good image formation.

According to a thirteenth aspect of the present invention, in the invention according to any one of the first to twelfth aspects, the developer is conveyed to the developing chamber through the opening toward the developing chamber. It is characterized in that it is provided with a conveying means for carrying out.

According to this structure, the developer in the accommodating chamber can be conveyed to the developing chamber while being agitated by the conveying unit, so that good image formation can be achieved.

The invention described in Item 14 is an image forming apparatus, which is characterized by including the developing device according to any one of Items 1 to 13.

When such a developing device is provided, an image having an appropriate density can be formed immediately after the use of the developing device is started.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side sectional view of an essential part showing an embodiment of a laser printer as an image forming apparatus of the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for feeding a sheet 3 into a main body casing 2.
Also, an image forming unit 5 for forming a predetermined image on the fed paper 3 is provided.

The feeder unit 4 has a paper feed tray 6 which is detachably mounted on the bottom of the main body casing 2, a paper pressing plate 7 provided in the paper feed tray 6, and one end side of the paper feed tray 6. A paper feed roller 8 and a paper feed pad 9 provided above the ends, paper dust removing rollers 10 and 11 provided downstream of the paper feed roller 8 in the transport direction of the paper 3, a paper dust removing roller 10 and The registration roller 12 is provided on the downstream side of the sheet 3 in the transport direction of the sheet 3.

The sheet pressing plate 7 is capable of stacking the sheets 3 in a stacked manner, and is swingably supported at the end portion far from the paper feed roller 8, so that the near end portion is vertically moved. It is movable in the direction, and is urged upward from the back side by a spring (not shown). Therefore, as the stacking amount of the sheets 3 increases, the sheet pressing plate 7 is swung downward against the biasing force of the spring with the end portion farther from the sheet feeding roller 8 as a fulcrum. The paper feed roller 8 and the paper feed pad 9 are arranged to face each other, and the paper feed pad 9 is pressed toward the paper feed roller 8 by a spring 13 provided on the back side of the paper feed pad 9. . The uppermost sheet 3 on the sheet pressing plate 7 is fed from the back side of the sheet pressing plate 7 by a spring (not shown) to the sheet feeding roller 8.
The sheet is pressed toward the sheet, is pinched by the sheet feeding roller 8 and the sheet feeding pad 9 by the rotation of the sheet feeding roller 8, and is then fed sheet by sheet. The fed paper 3 is fed to the paper dust removing roller 10
After 11 and 11, the paper dust is removed and the paper dust is sent to the registration roller 12. The registration roller 12 is composed of a pair of rollers, and after the paper 3 is subjected to a predetermined registration, an image forming position (a contact position between the photosensitive drum 27 and the transfer roller 30, that is, a toner image on the photosensitive drum 27 is The visual image) is sent to a transfer position) where the image is transferred to the sheet 3.

The feeder unit 4 further includes a multi-purpose tray 14, a multi-purpose side sheet feeding roller 15 and a multi-purpose side sheet feeding pad for feeding the sheets 3 stacked on the multi-purpose tray 14. 25
The multi-purpose side sheet feeding roller 15 and the multi-purpose side sheet feeding pad 25 are arranged to face each other, and the multi-side feeding roller 25 and the multi-purpose side sheet feeding pad 25 are arranged by a spring 25a disposed on the back side of the multi-purpose side sheet feeding pad 25. The paper feed pad 25 on the purpose side is pressed toward the paper feed roller 15 on the multipurpose side. The sheets 3 stacked on the multi-purpose tray 14 are sandwiched between the multi-purpose side sheet feeding roller 15 and the multi-purpose side sheet feeding pad 25 by the rotation of the multi-purpose side sheet feeding roller 15 and then fed one by one. To be paper.

The image forming section 5 includes a scanner unit 16,
The process unit 17 and the fixing unit 18 are provided.

The scanner unit 16 is provided in the upper part of the main body casing 2, and has a laser emitting portion (not shown),
It is equipped with a polygon mirror 19 which is driven to rotate, lenses 20 and 21, and reflecting mirrors 22, 23 and 24,
A polygonal mirror 19, a lens 20, reflecting mirrors 22 and 23, and a lens 2 are used to emit a laser beam based on predetermined image data emitted from the laser emitting section, as indicated by a chain line.
1. The light is passed through or reflected by the reflecting mirror 24 in this order, and the surface of the photosensitive drum 27 of the process unit 17, which will be described later, is irradiated by high-speed scanning.

The process unit 17 is disposed below the scanner unit 16, and as shown in FIG. 2, a photosensitive drum 27 and a developing device are provided in a drum cartridge 26 which is detachably attached to the main body casing 2. The developing cartridge 28, the scorotron charger 29, and the transfer roller 30 are provided.

As shown in FIG. 3, the developing cartridge 28 is detachably attached to the drum cartridge 26, and is divided into an accommodating chamber 34a for accommodating toner as a developer and a developing chamber 34b. Has been formed. The storage chamber 34a and the developing chamber 34b are separated from each other by a partition wall 51, and the partition wall 51 has a toner supply port 37 as an opening formed in a slit shape, which will be described in detail later.
Are formed.

An agitating / conveying member 55, which will be described in detail later, is rotatably provided in the accommodating chamber 34a, and positive charging non-magnetic one-component toner is filled therein as a developer. Examples of the toner include a polymerizable monomer, for example, a styrene-based monomer such as styrene, acrylic acid, alkyl (C1 to C4) acrylate, alkyl (C1 to C4).
4) A polymerized toner obtained by copolymerizing an acrylic monomer such as methacrylate by a known polymerization method such as suspension polymerization is used. Since such a polymerized toner has a substantially spherical shape and has extremely good fluidity, good development can be achieved, and as a result, a high quality image can be formed. In addition to such a toner, a coloring agent such as carbon black and a wax are mixed, and an external additive such as silica is added in order to improve fluidity. The average particle size is about 6 to 10 μm.

The toner in the storage chamber 34a is agitated and conveyed by a later-described agitating / conveying member 55 provided at the center of the storage chamber 34a.
The toner supply port 3 of the partition wall 51 provided between the storage chamber 34a and the developing chamber 34b is agitated by the rotation of the agitator 36 as a transporting means for the toner in the arrow direction (clockwise direction).
7 is conveyed to the developing chamber 34b. Incidentally, the accommodation chamber 34a
Both side walls 52 (see FIG. 4) are provided with windows 38 for detecting the remaining amount of toner, and the stirring and conveying member 5 described later
5 is cleaned by the cleaner 39 supported by the rotary shaft 35.

In the developing chamber 34b, there are provided a developing roller 31 as a developer carrying member, a layer thickness regulating blade 32 as a layer thickness regulating member, and a supply roller 33 as a supplying means.

The supply roller 33 is on the lower side in the developing chamber 34b, on the diagonally lower side of the toner supply port 37,
It is disposed below the toner conveyed to the developing chamber 34b in the direction of gravity so as to be rotatable in the arrow direction (counterclockwise direction). The supply roller 33 has a metal roller shaft covered with a roller made of a conductive sponge body. Further, the supply roller 33 extends from its uppermost portion to the ceiling portion of the developing chamber 34b, that is, the bottom surface of the elastic cover 73 of the toner pressing portion 70 of the pressing member 68 described later in the steady state shown in FIG. 3B. Are arranged such that the height of the is 30 mm or more.

In the developing chamber 34b, the developing roller 31 is located on the side of the supply roller 33 on the side opposite to the toner supply port 37, and to the side of the direction of gravity of the toner conveyed to the developing chamber 34b in the arrow direction ( It is rotatably provided in the counterclockwise direction. The developing roller 31 has a metal roller shaft covered with a roller made of an elastic material that is a conductive rubber material. More specifically, the developing roller 31 includes carbon particles or the like. The surface of the roller body made of conductive urethane rubber or silicone rubber containing is coated with a coating layer of urethane rubber or silicone rubber containing fluorine. A predetermined developing bias is applied to the developing roller 31 with respect to the photosensitive drum 27.

The supply roller 33 and the developing roller 31 are in contact with each other in such a state that they are compressed to some extent.

Further, a layer thickness regulating blade 32 is arranged near the developing roller 31. The layer thickness regulating blade 32 is arranged above the developing roller 31 so as to face each other along the axial direction of the developing roller 31. The layer thickness regulation blade 32 is used for the developing cartridge 2
8, a support member 90 attached to the casing, a plate spring member 91 made of a metal plate spring member extending from the support member 90 toward the upper portion of the developing roller 31, and a tip end portion of the plate spring member 91. And a pressing portion 40 having a semicircular cross-section made of insulating silicone rubber. The pressing portion 40 is developed by the elastic force of the leaf spring member 91.
It is constituted so that it is pressed onto the upper part 1.

Then, the toner supply port 3 from the storage chamber 34a
The toner conveyed to the developing chamber 34b via 7 is supplied to the developing roller 31 by the rotation of the supply roller 33, and at this time, positively frictionally charged between the supply roller 33 and the developing roller 31, and further, The toner supplied onto the developing roller 31 enters between the pressing portion 40 of the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates, and forms a thin layer having a constant thickness as the developing roller 31. Carried on top.

As shown in FIG. 2, the photosensitive drum 27 is located at a position lateral to the developing roller 31.
It is arranged so as to be rotatable in the direction of the arrow (clockwise) so as to face it. In the photosensitive drum 27, the drum body is grounded and the surface portion is formed of a positively chargeable photosensitive layer made of polycarbonate or the like.

The scorotron type charger 29 is arranged above the photosensitive drum 27 with a predetermined interval so as not to contact the photosensitive drum 27. The scorotron type charger 29 is a scorotron type charger for positive charging that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 27 to a positive polarity. ing.

The surface of the photosensitive drum 27 is uniformly positively charged by the scorotron charger 29 as the photosensitive drum 27 rotates, and then the laser beam from the scanner unit 16 is scanned at high speed. Is exposed to form an electrostatic latent image based on predetermined image data.

Next, when the toner carried on the developing roller 31 and positively charged comes into contact with the photosensitive drum 27 so as to face the photosensitive drum 27 due to the rotation of the developing roller 31, a static charge is formed on the surface of the photosensitive drum 27. An electrostatic latent image, that is, a surface of the photosensitive drum 27 that is uniformly positively charged, is supplied to an exposed portion whose potential is lowered by being exposed by a laser beam, and is selectively carried to be visualized. And thus reversal development is achieved.

The transfer roller 30 is arranged below the photosensitive drum 27 so as to face the photosensitive drum 27, and the transfer roller 30 is provided in the drum cartridge 26 in the arrow direction (counterclockwise direction).
It is rotatably supported by. This transfer roller 30 is
A metal roller shaft is covered with a roller made of a conductive rubber material, and a predetermined transfer bias is applied to the photosensitive drum 27 during transfer. Therefore, the visible image carried on the surface of the photosensitive drum 27 is transferred onto the paper 3 while the paper 3 passes between the photosensitive drum 27 and the transfer roller 30.

As shown in FIG. 1, the fixing unit 18 is disposed on the downstream side of the process unit 17, and is provided with the heating roller 4.
1, a pressing roller 42 for pressing the heating roller 41, and a pair of conveying rollers 43 provided on the downstream side of the heating roller 41 and the pressing roller 42. The heating roller 41 is made of metal and is provided with a halogen lamp for heating. While the paper 3 passes between the heating roller 41 and the pressing roller 42, the toner transferred onto the paper 3 in the process unit 17 is passed. Heat fix to
The sheet 3 is conveyed to the sheet discharge path 44 by the conveying roller 43. The paper 3 sent to the paper discharge path 44 is sent to the paper discharge roller 45, and the paper discharge roller 45
Then, the sheet is discharged onto the sheet discharge tray 46.

Further, the laser printer 1 has a paper 3
A reverse transport unit 47 is provided to form images on both sides of the sheet. The reversing conveyance unit 47 is provided with the paper discharge roller 45.
A reverse transport path 48, a flapper 49, and a plurality of reverse transport rollers 50.

The paper discharge roller 45 is composed of a pair of rollers and is configured to be capable of switching between forward rotation and reverse rotation. This paper discharge roller 45 is, as described above,
When the paper 3 is discharged onto the paper discharge tray 46, the paper 3 rotates in the forward direction, but when the paper 3 is reversed, the paper 3 rotates in the reverse direction.

The reverse transport path 48 is provided along the vertical direction so that the sheet 3 can be transported from the paper discharge roller 45 to a plurality of reverse transport rollers 50 disposed below the image forming section 5. The upstream end is arranged near the discharge roller 45, and the downstream end is arranged near the reverse conveyance roller 50.

The flapper 49 is swingably provided so as to face the branch portion between the paper discharge path 44 and the reversal conveyance path 48, and is reversed by the paper discharge roller 45 by the excitation or non-excitation of a solenoid (not shown). The conveyance direction of the ejected sheet 3 can be switched from the direction toward the paper discharge path 44 to the direction toward the reverse conveyance path 48.

A plurality of reversing / conveying rollers 50 are provided in a substantially horizontal direction above the paper feeding tray 6, and the reversing / conveying rollers 50 on the most upstream side are arranged near the rear end of the reversing / conveying path 48. In addition, the reverse conveyance roller 50 on the most downstream side is provided so as to be arranged below the registration roller 12.

When forming an image on both sides of the sheet 3, the reversal conveyance section 47 is operated as follows. That is, the sheet 3 having the image formed on one surface is discharged from the sheet discharge path 44 to the sheet discharge roller 45 by the transport roller 43.
When the sheet 3 is fed to the sheet, the sheet discharge roller 45 rotates normally while sandwiching the sheet 3 and once conveys the sheet 3 toward the outer side (the sheet discharge tray 46 side). When the paper 3 is sent to the outside and the rear end of the paper 3 is nipped by the paper discharge roller 45, the forward rotation is stopped. Next, the paper discharge roller 45 rotates in the reverse direction, and the flapper 49 causes the paper 3 to be reversed in the conveyance path 4
8 and the paper 3 is switched.
Are conveyed to the reverse conveyance path 48 in the state of being reversed in the front-rear direction. When the conveyance of the paper 3 is completed, the flapper 49 is switched to the original state, that is, the state in which the paper 3 sent from the carry roller 43 is sent to the paper discharge roller 45. Next, the sheet 3 conveyed in the reverse direction to the reverse conveying path 48 is conveyed to the reverse conveying roller 50, is reversed upward from the reverse conveying roller 50, and is sent to the registration roller 12. The sheet 3 conveyed to the registration roller 12 is turned upside down, and after being again subjected to a predetermined registration, is sent toward the image forming position, whereby a predetermined image is formed on both sides of the sheet 3.

In the laser printer 1, the photosensitive drum 2 is transferred after being transferred onto the sheet 3 by the transfer roller 30.
Residual toner remaining on the surface of No. 7 is collected by the developing roller 31, that is, a so-called cleanerless system. If the residual toner on the surface of the photosensitive drum 27 is collected by such a cleanerless system, it is not necessary to provide a cleaner device such as a blade or a waste toner storage means, which simplifies the device configuration, reduces the size, and reduces the cost. It can be reduced.

In the laser printer 1 as described above, the toner supply port 37 of the developing cartridge 28 has a toner passage port 62 opened in a vertically elongated shape (height direction) as a substantially rectangular shape as shown in FIG. However, a plurality of slits are formed substantially at the lower side in the vertical direction of the partition wall 51 at predetermined intervals in the width direction (direction orthogonal to the vertical direction), so that openings are formed in a slit shape.

More specifically, as shown in FIG. 5, for example, the length X in the vertical direction of the toner passage port 62 is
The width Y is about 10 to 15 mm, and the length Y in the width direction is about 1 mm. Further, for example, the distance Z between each adjacent toner passage port 62 is set to about 1.5 mm.

The toner supply port 37 has a length in the width direction (that is, a portion where the toner passage port 62 is formed in the width direction) in the photosensitive drum 2.
The image forming area 7 (electrostatic latent image forming area) has a length substantially equal to that of the image forming area.

Further, as shown in FIG. 2, the partition wall 51 is provided with a shutter member 63 as a shielding member.

As shown in FIG. 3, the shutter member 63 has an elongated rectangular plate shape, and the developing chamber 34b of the partition wall 51.
The toner supply port 37 is provided at a position opposite to the toner supply port 37 on the side. The shutter member 63 is provided with the same number of shutter openings 64 in the width direction as the toner passage openings 62 of the toner supply opening 37 at the same intervals as the toner passage openings 62. Further, one end in the width direction of the shutter member 63 has an outer protruding portion 65.
Is projected from the side wall 52 on one side of the accommodation chamber 34a, and an engaging portion 67 that projects downward in the vertical direction is integrally provided at the end of the outer protruding portion 65. A spring 66 is interposed between the locking portion 67 and the side wall 52, and the locking portion 67 is urged by the spring 66.
Is always urged toward the outer side in the width direction with respect to the side wall 52.

When the developing cartridge 28 is not attached to the laser printer 1 and is not attached, the shutter member 63 is urged against the developing cartridge 28 by the urging force of the spring 66, as shown in FIG. 4B. It has been moved in the direction of arrow B (rightward in FIG. 4). As a result, as shown in FIG. 5B, the toner supply port 37
The toner passage port 62 and the shutter port 64 are not overlapped with each other, the toner passage port 62 of the toner supply port 37 is closed by the shutter member 63, and the storage chamber 34a and the developing chamber 34b are closed. .

On the other hand, when the developing cartridge 28 is mounted on the laser printer 1, the outer projecting portion 65 comes into contact with the contact portion 2a provided on the main body casing 2 and resists the biasing force of the spring 66. 4A, the shutter member 63 is moved in the direction of arrow A (leftward in FIG. 4) with respect to the developing cartridge 28, as shown in FIG. 4A. As a result, as shown in FIG. 5A, the toner passage port 62 of the toner supply port 37 and the shutter port 64 are brought into a state of overlapping with each other, and the shutter port 64 of the shutter member 63 causes the toner supply port 3 to move.
The toner passage port 62 of No. 7 is opened, and the accommodation chamber 34a and the developing chamber 34b are opened for communication.

Further, as shown in FIG. 3, the agitating / conveying member 55 of the developing cartridge 28 is arranged in the substantially central portion of the accommodating chamber 34a, and is provided with a rotary shaft 35, an agitator 36 and a cleaner 39.

As shown in FIG. 4, both ends of the rotary shaft 35 are inserted into and supported by a support hole 56 provided at a substantially central portion of the side wall 52 of the housing chamber 34a, and one end of the rotary shaft 35 is housed. It projects outside the chamber 34a. A gear 57 is provided at one end protruding outside the accommodation chamber 34a, and the rotation shaft 35 is configured to rotate by transmitting power from a drive source (not shown) to the gear 57. Has been done.

The agitator 36 includes a base portion 58 (see FIG. 3) having a substantially rectangular cross section which is provided over substantially the entire axial direction of the rotary shaft 35 in the accommodating chamber 34a, and a free end portion of the base portion 58 as shown in FIG. Conveyor plate 59 provided on one side of
And a film member 60 attached to the free end of the transport plate 59 along the axial direction of the rotary shaft 35.

The transport plate 59 has a plate shape whose length in the width direction (that is, the axial direction of the rotary shaft 35) is substantially equal to the length corresponding to the image forming area (electrostatic latent image forming area) of the photosensitive drum 27. A plurality of substantially rectangular openings 59a for reducing agitation resistance are formed along the width direction on the base 58 side thereof at predetermined intervals.

The film member 60 is in the form of a film made of PET (polyethylene terephthalate) or the like, and is attached along the width direction to the free end side of the transport plate 59 in the rotation direction of the stirring and transporting member 55. .

In the agitator 36, when the rotary shaft 35 is driven to rotate, the free end portion of the film member 60 rubs the bottom portion in the accommodating chamber 34a, and then the entire surface of the toner supply port 37 of the partition wall 51 is predetermined. Rub with the pressing force of. Therefore, the toner in the storage chamber 34a is scraped up by the film member 60 from the bottom of the storage chamber 34a, and is conveyed while being pushed from the toner passage port 62 of the toner supply port 37 toward the developing chamber 34b. It In the film member 60, the pressing force when the film member 60 pushes the toner from the toner passage port 62 of the toner supply port 37 toward the developing chamber 34b is a predetermined amount of the toner in the developing chamber 34b which will be described later. The pressure of the toner in the developing chamber 34b at a certain time is set to be substantially equal.

Since the agitator 36 is formed in a substantially uniform shape in the width direction as described above, it has substantially the same toner transporting ability in the width direction. Therefore, the toner in the storage chamber 34a is conveyed by the agitator 36 from the toner passage opening 62 to the developing chamber 34b substantially equally in the width direction.

The cleaner 39 has a plate-shaped member 61 extending in the opposite direction to the direction in which the transport plate 59 extends at both axial ends of the rotary shaft 35, and a cleaning member provided at the end of the plate-shaped member 61. 61a and. Each plate-shaped member 61 has a substantially L shape, and one side thereof is formed along the rotation axis 35, and the other side orthogonal to the one side is formed so as to face the side wall 52. Each cleaning member 61 a is made of a substantially rectangular plate-shaped elastic body, and the other side of each plate-shaped member 61 is provided with the accommodation chamber 34 of each side wall 52.
It is attached so that the window 38 of a can be wiped off.

In the developing chamber 34b of the developing cartridge 28, as shown in FIG. 3, a pressing member 6 as a pressing means for pressing the toner toward the supply roller 33.
8 are provided.

The pressing member 68 is provided on the upper wall 53 of the developing chamber 34b above the supply roller 33, and has a handle portion 69, a toner pressing portion 70, and a pressing sponge member 71.
It has and.

The handle portion 69 has a substantially T-shaped cross section composed of a plate-shaped handle portion 74 and a shaft portion 75 formed so as to project downward from the central portion of the handle portion 74. 75 is inserted so as to penetrate the upper wall 53 in the vertical direction. A lock member 76 capable of projecting radially outward is provided in the axial direction of the shaft portion 75.
6 is urged by an elastic member (not shown) mounted in the shaft portion 75 so that a part thereof projects outward in the radial direction of the shaft portion 75.

The toner pressing portion 70 is inserted into the space surrounded by the partition wall 51, the front wall 54 and the side walls 52 at the upper part of the developing chamber 34b, and is integrally provided at the lower end portion of the shaft portion 75. The pressing main body 72 and the elastic cover 73 are provided. The pressing body 72 is an elastic cover 7 made of an elastic body.
3 covers the sides and the lower side of the developing chamber 34b.
Is closely fitted in a space surrounded by the partition wall 51, the front wall 54, and the side walls 52 in the upper part of the.

The pressing sponge member 71 is made of a sponge body and is interposed in a compressed state between the lower surface of the upper wall 53 and the upper surface of the pressing body 72 of the toner pressing portion 70 on the outer periphery of the shaft portion 75. .

Before the use of the developing cartridge 28 is started, the pressing member 68 pushes down the toner pressing portion 70 by the elastic force of the pressing sponge member 71, as shown in FIG. 3A. The toner in the developing chamber 34b is pressed toward the supply roller 33 by the toner pressing portion 70. Further, at this time, the lock member 76 provided on the shaft portion 75 has the upper wall 5 of the developing chamber 34b.
The protrusion is restricted by the inner peripheral surface of 3, and is housed in the shaft portion 75.

The steady state of the developing cartridge 28,
That is, at the time of image formation, the handle portion 69 is pulled upward, the pressing sponge member 71 is compressed, and the toner pressing portion 70 is brought closer to the upper wall 53 of the developing chamber 34b. As a result, the pressing of the toner in the developing chamber 34b against the supply roller 33 by the toner pressing portion 70 is released. At this time, the lock member 76 provided on the shaft portion 75 is positioned above the upper wall 53 by the upward movement of the handle portion 69, and the restriction by the upper wall 53 is released. The elastic force of an elastic member (not shown) inside 75 causes the elastic member to project outward in the radial direction, thereby restricting the downward movement of the handle 69.

Next, a series of processes until the developing cartridge 28 is mounted on the laser printer 1 and a steady state in which an image is formed will be described.

First, before shipment of the developing cartridge 28, a new toner is filled in the accommodating chamber 34a of the developing cartridge 28, and then, in order to enable good image formation immediately after the mounting to the laser printer 1, The developing chamber 34b is filled with the new toner.

To fill the developing chamber 34b with new toner,
First, as shown in FIG. 3B (however, at this time,
The toner in the developing chamber 34b is empty. ), With the handle portion 69 of the pressing member 68 pulled up, the outer protruding portion 65 of the shutter member 63 is attached to the developing cartridge 28.
Press inward. Then, the shutter member 63 is moved toward the inside of the developing cartridge 28 (direction of arrow A), and as shown in FIGS. 4A and 5A, the shutter port 64 of the shutter member 63 and the toner supply port. The toner passage port 62 of 37 is aligned,
The toner supply port 37 is opened like a slit between the storage chamber 34a and the developing chamber 34b.

Next, a motor (not shown) is connected to the gear 57 of the rotary shaft 35 of the stirring / transporting member 55, and the motor is driven to rotate the stirring / transporting member 55. Then, the agitator 36 conveys the toner in the storage chamber 34a from the storage chamber 34a to the developing chamber 34b through the toner supply port 37. Then, the toner is sufficiently filled in the developing chamber 34b such that the upper surface (water level) of the toner conveyed into the developing chamber 34b reaches the vicinity of the bottom surface of the elastic cover 73 of the toner pressing portion 70. At the same time, the driving of the motor is stopped and the rotation of the agitator 36 is stopped. Then, when the pressing of the outer protruding portion 65 of the shutter member 63 is released, the shutter member 63 is moved in the arrow B direction by the biasing force of the spring 66, as shown in FIGS. 4B and 5B. The shutter opening 64 of the shutter member 63 and the toner passage opening 6 of the toner supply opening 37
2 is shifted from each other, and the toner supply port 37 is closed between the storage chamber 34a and the developing chamber 34b.

Next, the handle portion 69 of the pressing member 68 is pushed down. Then, the lock member 76 retracts into the shaft portion 75, and the elastic force of the pressing sponge member 71 causes the toner pressing portion 70 to press the toner in the developing chamber 34b toward the supply roller 33. As a result, before the use of the developing cartridge 28 is started, the developing chamber 34b is sufficiently filled with toner, and the filled toner is pressed by the pressing member 68 toward the supply roller 33. .

Therefore, in the developing chamber 34b before the use of the developing cartridge 28 is started, the toner density is higher than the loose apparent density. More specifically, the toner density is 2 g or more per cm in the width direction. Is filled, and the height of the filled toner is 25 mm or more from the upper portion of the supply roller 33.

The loose apparent density is the density in a state where the toner is sieved and is still sieved off. The toner used in the laser printer 1 is set to about 0.4 g / ml, for example. There is. In addition,
The loose apparent density can be measured using, for example, a powder tester manufactured by Hosokawa Micron.

Then, in this state, the developing cartridge 28 is shipped and mounted by the user on the laser printer 1 at the start of use. At the beginning of use, first
Before mounting the developing cartridge 28 on the laser printer 1, the handle portion 69 of the pressing member 68 is pulled up. Then, the pressing sponge member 71 is compressed, and the pressing of the toner in the developing chamber 34b against the supply roller 33 by the toner pressing portion 70 is released.

Next, the developing cartridge 28 is attached to the laser printer 1. Then, as described above, as shown in FIGS. 4A and 5A, the toner passage port 62 and the shutter port 64 of the shutter member 63 are aligned with each other, and the toner supply port 37 is opened. The storage chamber 34a and the developing chamber 34b are communicated with each other. Then, the laser printer 1 is activated to start image formation.

Then, before the use of the developing cartridge 28 is started, the passage of the toner between the accommodating chamber 34a and the developing chamber 34b is prohibited by the shutter member 63, and the developing chamber 34b has Since the toner is filled with a density larger than the loose apparent density, more specifically, 2 g or more per 1 cm in the width direction, the toner in the developing chamber 34b is sufficiently secured at the start of image formation. There is. Therefore, even immediately after the start of image formation, the toner is sufficiently supplied to the developing roller 31 due to its own weight, and as a result, the developing roller 31 is
It is possible to secure a sufficient amount of the toner to be carried and to form an image with an appropriate density.

Further, before the use of the developing cartridge 28 is started, the toner in the developing chamber 34b is pressed toward the supply roller 33 by the pressing member 68, so that the supply roller 33 is pressed at the start of image formation. On the other hand, it is possible to form a state in which the pressure from the toner is positively applied. Therefore, the amount of toner supplied to the developing roller 31 immediately after the start of use can be reliably ensured, so that the carrying amount of the developing roller 31 can be more reliably ensured, and an image having an appropriate density is formed. be able to.

Further, before the developing cartridge 28 is attached to the laser printer 1, the handle portion 69 of the pressing member 68 is pulled upward, so that the pressing force of the toner pressing portion 70 on the toner in the developing chamber 34b is increased. Since the toner can be released, the toner can be made to flow in the developing chamber 34b at the start of image formation. Therefore, after the mounting, the toner can be circulated in the developing chamber 34b, and as a result, a better image formation can be achieved due to the stabilization of the charging.

Further, in this developing cartridge 28, the height of the toner in the developing chamber 34b is
From the top of the supply roller 33 to be 25 mm or more,
Since the developing chamber 34b is filled with toner, the supply roller 33 can reliably hold the toner and supply it to the developing roller 31 by the pressure received from the toner. Therefore, the amount of toner carried on the developing roller 31 can be secured more reliably. As a result, an image having an appropriate density can be formed.

Further, in the developing cartridge 28, the shutter member 63 can open and close the toner supply port 37,
Before the use of the developing cartridge 28 is started, the toner supply port 37 is closed by the shutter member 63, and the developing chamber 34 is closed.
Toner can be satisfactorily filled in b, and the toner supply port 37 can be opened at the start of use to supply the toner from the accommodation chamber 34a into the developing chamber 34b through the toner supply port 37. Therefore, with a simple configuration,
Filling the developing chamber 34b with toner before the start of use, and storing chamber 34a in the developing chamber 34b after mounting.
Toner supply from can be achieved.

When the laser printer 1 is activated and image formation is started, the agitator 3 of the agitating / conveying member 55 is moved.
By the rotational driving of 6, the conveyance of the toner in the storage chamber 34a to the developing chamber 34b via the toner supply port 37 is started.

After that, since the toner supply port 37 is formed in a slit shape, the pressing force of the agitator 36 causes the toner supply port 37 toward the developing chamber 34b from the accommodating chamber 34a.
While the toner is allowed to be conveyed, the passage of the toner from the developing chamber 34b to the storage chamber 34a is restricted, and the toner is prevented from returning to the storage chamber 34a again. Therefore, at the time of image formation, the amount of toner in the developing chamber 34b is reduced to the storage chamber 3
A predetermined amount is maintained regardless of the amount of toner in 4a.

When the amount of toner in the developing chamber 34b is already a predetermined amount, the film member 60 of the agitator 36 has a pressing force for pushing the toner toward the developing chamber 34b through the toner supply port 37. Since the pressure of the toner in the developing chamber 34b is substantially equal to that of the agitator 3,
Due to the conveying force of 6, the toner of the amount larger than that is developed in the developing chamber 34b.
It is restricted to be transported inside.

More specifically, in such a steady state of image formation, the amount of toner in the developing chamber 34b depends on the height of the upper surface (water level) of the toner and the pressing force of the agitator 36 at the toner supply port 37. It is higher than the acting portion, and is 25 mm or more from the upper part of the supply roller 33, and the upper surface (water level) of the toner and the ceiling portion of the developing chamber 34b,
That is, the amount is maintained such that a predetermined gap (about 3 to 10 mm) is formed between the toner pressing portion 70 and the bottom surface of the elastic cover 73. In this steady state, the developing chamber 34b is filled with 2 g or more of toner per cm in the width direction by the conveyance of the agitator 36.

Therefore, in this developing cartridge 28, a sufficient amount of toner can be secured in the developing chamber 34b even in a steady state, regardless of the decrease in the amount of toner in the accommodating chamber 34a, and the supply roller 33 is By the pressure received from the toner, the toner can be reliably held and supplied to the developing roller 31. Therefore, the amount of toner carried on the developing roller 31 can be reliably ensured. As a result, it is possible to reduce the decrease in the image forming density after being left standing. Even in the initial printing, the toner is rapidly conveyed into the developing chamber 34b, so that the initial density reduction can be reduced.

Further, in the developing cartridge 28, when the amount of toner in the developing chamber 34b reaches a predetermined amount, the pressure of the toner in the developing chamber 34b to the toner supply port 37 and the agitator to the toner supply port 37. Since the pressing force of the developing chamber 36 is substantially equal to that of the developing chamber 3,
When the amount of toner in the developing chamber 34b does not reach the predetermined amount, the amount of toner in the developing chamber 34b increases due to the conveyance of the toner by the pressing force of the agitator 36, while the amount of toner in the developing chamber 34b increases.
When the amount of toner in the inside reaches a predetermined amount, the pressing force of the agitator 36 to the toner supply port 37 and the pressure of the toner in the developing chamber 34b to the toner supply port 37 become equal to each other. The conveyance of toner from the agitator 36 toward the developing chamber 34b is restricted. As a result, in the developing chamber 34b, it is possible to always maintain a predetermined amount of toner without excess or deficiency, so that the developing roller 31 can secure the toner carrying amount regardless of the amount of toner in the accommodating chamber 34a. Therefore, it is possible to reduce a decrease in image forming density.

For example, if the developing chamber 34b is filled with toner without a gap, it may be difficult for the toner to circulate and the charging may become nonuniform. If a gap is formed between the elastic cover 73 and the bottom surface of the elastic cover 73, the toner in the developing chamber 34b can circulate well, so that uniform charging is ensured and good image formation is achieved. Can be achieved.

In the developing cartridge 28, since the height from the upper portion of the supply roller 33 to the bottom surface of the elastic covering body 73 of the toner pressing portion 70 is 30 mm or more, the distance between the toner and the bottom surface of the elastic covering body 73 is increased. Even if you create a gap in
A sufficient amount of toner can be secured in the developing chamber 34b. Therefore, the supply roller 33 can satisfactorily supply the toner to the developing roller 31 while circulating the toner. As a result, it is possible to further reduce the decrease in image forming density.

Further, in this developing cartridge 28,
In the developing chamber 34b, the toner is filled with 2 g or more per 1 cm in the width direction, so that the toner in the developing chamber 34b is sufficiently secured. Therefore, it is possible to secure a sufficient amount of toner carried by the developing roller 31. As a result, it is possible to further reduce the decrease in image forming density.

The lengths of the toner supply port 37 and the agitator 36 of the developing cartridge 28 in the width direction are substantially equal to the length corresponding to the image forming area of the photosensitive drum 27 developed by the developing roller 31. Therefore, the toner can be supplied from the storage chamber 34a through the toner supply port 37 in the width direction of the developing roller 31 of the developing chamber 34b without excess or deficiency, and good image formation can be achieved. it can. In addition, the toner supply port 37
Is configured such that the toner does not easily return from the developing chamber 34b to the storage chamber 34a. For example, if the width of the toner supply port 37 in the width direction is short, the toner is not formed in a portion where the toner supply port 37 is not formed. However, such a defect can be prevented.

Further, since the agitator 36 has substantially the same carrying capacity in the width direction, the toner in the accommodating chamber 34a is uniformly supplied into the developing chamber 34b in the width direction of the toner supply port 37. be able to. Therefore, the amount of toner carried can be secured uniformly in the width direction of the developing roller 31. As a result, it is possible to further reduce the decrease in image forming density.

Further, in the developing cartridge 28, the supply roller 33 and the developing roller 31 are arranged so as to be in pressure contact with each other, so that the supply roller 33 ensures a sufficient amount in the developing chamber 34b. The toner contained in the developing roller 31 can be sufficiently supplied to the developing roller 31, and the toner supplied to the developing roller 31 can be favorably charged between the supplying roller 33 and the developing roller 31.
In addition, it is possible to reliably supply the charged toner between the supply roller 33 and the developing roller 31.

In the developing chamber 34b, the supply roller 33 is located below the developing chamber 34b so that the gravity of the toner acts in the developing chamber 34b.
The toner carried by the agitator 36 is arranged below the toner conveyed in the direction of gravity, and the toner is fed by the agitator 36.
3, the toner carried into the developing chamber 34b is carried above the supply roller 33, and the own weight of the carried toner acts on the supply roller 33. To do. Therefore, the supply roller 33 is
Due to the pressure received from the toner, the toner can be reliably held and satisfactorily supplied to the developing roller 31.
As a result, the amount of toner carried on the developing roller 31 can be secured more reliably. As a result, it is possible to further reduce the decrease in image forming density, and it is possible to form an image having an appropriate density.

Further, in the developing cartridge 28, the developing roller 31 is arranged laterally in the direction of gravity of toner in the developing chamber 34b, and the plate spring member 91 of the layer thickness regulating blade 32 is conveyed to the developing chamber 34b. The toner is arranged between the toner and the developing roller 31 so as to restrict the gravity of the toner from directly acting on the developing roller 31.

For example, when the developing roller 31 and the toner are not partitioned by the leaf spring member 91 of the layer thickness regulating blade 32 and the self-weight of the toner directly acts on the developing roller 31, the toner is supplied to the supply roller 33. Since the toner is directly carried by the developing roller 31 without being charged between the developing roller 31 and the developing roller 31, the charging becomes unstable.

However, as described above, the developing roller 31 is disposed on the side of the developing chamber 34b in the direction of gravity of the toner, and the layer thickness regulating blade 32 causes the gravity of the toner conveyed to the developing chamber 34b to the developing roller 31. If the toner is disposed between the toner and the developing roller 31 so as not to act directly, it is possible to restrict the gravity of the toner from directly acting on the developing roller 31, so that the developing roller 31 is not loaded with its own weight. It becomes difficult to act directly. Therefore, the toner charged reliably between the supply roller 33 and the developing roller 31 is supplied to the developing roller 31, and stable toner charging can be secured.

Since the toner supply port 37 of the developing cartridge 28 is formed in a slit shape,
The toner supply port 37 has a simple structure, and is operated from the toner storage chamber 34 a by the action of the agitator 36 to the developing chamber 34.
It is possible to allow the toner to be transferred to the developing chamber 34b and to restrict the toner that has been transported to the developing chamber 34b from the developing chamber 34b to the storage chamber 34a. Therefore, it is possible to more simply and surely secure a sufficient amount of toner in the developing chamber 34b,
The amount of toner carried on the developing roller 31 can be secured. As a result, it is possible to further reduce the decrease in image forming density.

A pressure release port for releasing the toner filling pressure in the developing chamber 34b may be provided above the toner supply port 37 in the partition wall 51 between the storage chamber 34a and the developing chamber 34b. FIG. 6 shows a sectional side view of the main part of such a developing cartridge 28. In addition, in FIG.
The same members as those of the developing cartridge 28 shown in
The same reference numerals are given and the description is omitted.

In FIG. 6, this developing cartridge 28
The partition wall 51 between the storage chamber 34a and the developing chamber 34b is divided into an upper partition wall 51a and a lower partition wall 51b in the vertical direction, and the upper partition wall 51a and the lower partition wall 51b.
Between b and b, an upper opening 80 is formed as a substantially rectangular pressure release port (communication port) that extends in the width direction and that communicates the storage chamber 34a and the developing chamber 34b.

The upper opening 80 has a substantially rectangular shape elongated in the width direction. For example, the length in the up-down direction is about 3 to 10 mm, and the length in the width direction is in the width direction. The toner passage port 62 is formed to have a length substantially equal to the length of the portion where the opening is formed. The upper opening 80 is not limited to the above-described shape, and for example, a plurality of openings are formed so as to be arranged in the width direction substantially equal to the length of the portion where the toner passage opening 62 is formed. Good.

An opening / closing mechanism 81 is provided in the upper opening 80. The opening / closing mechanism 81 includes a gate member 82, an upper foam elastic body 83, and a lower foam elastic body 84. ing.

The gate member 82 has a plate shape, extends in the width direction of the upper opening 80, and is slidably fitted in the vertical direction at substantially central portions in the thickness direction of the upper partition wall 51a and the lower partition wall 51b. . A gate opening 87 having substantially the same shape as the upper opening 80 is formed in the middle of the gate member 82 in the vertical direction. Also, at its upper end,
A pressed portion 86 having a substantially semicircular cross section is provided.

The upper foam elastic body 83 is provided in the upper partition wall 51a so as to sandwich the gate member 82 from both the accommodation chamber 34a side and the developing chamber 34b side.

The lower foaming elastic member 84 is provided in the lower partition wall 51b so that the lower end of the gate member 82 can come into contact with the lower partition member 51b, and the elastic force of the lower foaming member 84 always attaches the gate member 82 upward. I am energetic.

When the developing cartridge 28 is not attached to the laser printer 1, the gate member 82 is attached upward by the elastic force of the lower foam elastic body 84, as shown in FIG. 6A. And the pressed portion 86 is
The gate opening 87 is opposed to the upper foam elastic body 83 in the upper partition wall 51a while protruding from the upper portion of the developing cartridge 28 to a predetermined position. Thereby, the upper opening 80 is closed by the lower portion of the gate opening 87 in the gate member 82.

On the other hand, when the developing cartridge 28 is mounted on the laser printer 1, the upper end of the pressed portion 86 contacts the contact portion 2b provided on the main body casing 2 of the laser printer 1, and the gate member 82 is removed. It is pressed downward. As a result, as shown in FIG.
The pressed portion 86 is pushed down until it comes into contact with the upper wall 53 of the developing cartridge 28, the gate member 82 is moved downward against the elastic force of the lower foam elastic body 84, and the gate member 8
The second gate opening 87 is aligned with the upper opening 80,
The upper opening 80 is opened so as to communicate between the accommodation chamber 34a and the developing chamber 34b.

Then, in a series of processes until the developing cartridge 28 is mounted on the laser printer 1 and a steady state in which image formation is performed, first, before shipment of the developing cartridge 28, in the same manner as described above. The shutter member 63 is pressed toward the inside of the developing cartridge 28 (direction of arrow A in FIG. 5) to open the toner supply port 37 in a slit shape between the storage chamber 34a and the developing chamber 34b. In this state, the gate member 82 is pressed upward by the elastic force of the lower foam elastic body 84, and the upper opening 80 is closed by the lower part of the gate foam 87 of the upper elastic foam 83. .

Next, a motor and an agitating / conveying member 5 (not shown)
The gear 57 of the rotary shaft 35 of No. 5 is connected and the motor thereof is driven to rotationally drive the agitating / conveying member 55, and the agitator 36 moves from the accommodation chamber 34a to the developing chamber 34b via the toner supply port 37. Transport toner.
Then, as shown in FIG. 6A, when the developing chamber 34b is sufficiently filled with toner, driving of the motor is stopped, rotation of the agitator 36 is stopped, and then,
Release the pressing of the external protruding portion 65 of the shutter member 63,
The toner supply port 37 is closed.

As a result, a sufficient amount of toner is filled in the developing chamber 34b of the developing cartridge 28 before the start of use, as described above.

Then, in this state, when the developing cartridge 28 is shipped and mounted on the laser printer 1 at the start of use by the user, the toner supply port 37 is opened and the upper opening is opened as described above. Since 80 is also opened, the developing chamber 34 can be opened from the upper opening 80.
The filling pressure of the toner filled in b is released.

Therefore, by closing the upper opening 80 before starting the use of the developing cartridge 28, the toner in the developing chamber 34b can be filled more densely and the developing roller 31 at the start of use. It is possible to reliably secure the amount of toner to be carried. Further, after the start of use, the upper opening 80 is opened, so that even if the pressing force by the agitator 36 is large, when the toner of a predetermined amount or more is conveyed into the developing chamber 34b, the upper opening 80 is opened.
The toner in the developing chamber 34b is returned to the inside of the accommodating chamber 34a via the. Therefore, until the amount of toner in the developing chamber 34b reaches a predetermined amount, the amount of toner in the developing chamber 34b increases due to the toner conveyance by the pressing force of the agitator 36, while the amount of toner in the developing chamber 34b increases. Reaches a predetermined amount, and when a predetermined amount or more of toner is conveyed, the toner that has been conveyed into the developing chamber 34b by a predetermined amount or more is returned toward the storage chamber 34a through the upper opening 80. As a result, in the developing chamber 34b, the toner can always be kept at a predetermined amount without excess or deficiency, so that the developing roller 31
Can secure the amount of toner carried regardless of the amount of toner in the storage chamber 34a, and can reduce the decrease in image forming density. Further, by preventing the toner from being excessively filled in the developing chamber 34b and accelerating the flow of the toner, it is possible to achieve better image formation by stabilizing the charging.

Further, in such a developing cartridge 28, two walls may be provided between the developing chamber 34b and the accommodating chamber 34a, and an opening may be provided in each of the walls. Such a developing cartridge 28 is shown in FIG. In FIG. 7, the same members as those of the developing cartridge 28 shown in FIGS. 1 to 6 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 7, this developing cartridge 28
Is a partition wall 51 that defines the developing chamber 34b and the accommodating chamber 34a.
An auxiliary partition wall 92 is provided laterally on the developing chamber 34b side.

The auxiliary partition wall 92 is bonded to the partition wall 51 on the side of the developing chamber 34b, and the upper flat portion 93 is bonded to the partition wall 51 in the vicinity of the upper part of the partition wall 51 where the toner supply port 37 is formed. The lower flat portion 94 joined near the lower portion of the partition 51 in the vertical direction where the toner supply port 37 is formed, and the upper flat portion 93 and the lower flat portion 94 have a substantially V-shaped cross section. The bent portion 95 that is bent is integrally formed.

The bent portion 95 is formed as a first slanted wall 96 that is slanted downward from the lower end of the upper flat portion 93 toward the inside of the developing chamber 34b (that is, the downstream side in the toner transport direction). Then, a second inclined wall 97, which is formed by obliquely bending downward from the lower end of the first inclined wall 96 toward the lower flat portion 94, is continuously formed.

At the substantially vertical center of the second inclined wall 97,
An auxiliary toner supply port 98 as an opening is provided so as to substantially face the toner supply port 37 in the width direction. In this auxiliary toner supply port 98, the same number of auxiliary toner passage ports 99 as the toner passage port 62 of the toner supply port 37 are formed along the width direction at substantially the same intervals as the toner passage ports 62. .

Due to such a bent portion 95, a space 100 surrounded by the toner supply port 37 of the partition wall 51, the first inclined wall 96 and the second inclined wall 97 is provided between the partition wall 51 and the auxiliary partition wall 92. It is formed.

In the developing cartridge 28,
When the toner is conveyed by the agitator 36 from the accommodation chamber 34a toward the development chamber 34b, the toner first passes through the toner supply port 37 formed in a slit shape by the plurality of toner passage ports 62, and the accommodation chamber 34a. Is transported to the space 100. Next, the toner conveyed to the space 100 is further pressed by the toner that passes through the toner supply port 37 from the storage chamber 34 a by the pressing force of the agitator 36, and the incident toner passage port 9 of the second inclined wall 97.
9 is conveyed to the developing chamber 34b. In this transportation,
Since the incident toner supply port 98 of the second inclined wall 97 is formed so as to be directed obliquely downward, the toner also favorably passes through the incident toner supply port 98 due to its own weight.

On the other hand, the toner conveyed into the accommodating chamber 34a is difficult to move toward the space 100 and passes to the accommodating chamber 34a side because the incident toner supply port 98 is formed so as to open obliquely downward. Is more reliably prevented.

As described above, the above-mentioned developing cartridge 2
In FIG. 8, the toner in the storage chamber 34 a first passes through the toner supply port 37 of the partition wall 51 by the pressing force of the agitator 36 and is conveyed to the space 100, and then the additional toner supply port 98 of the auxiliary partition wall 92. And is conveyed to the developing chamber 34b. On the other hand, the toner in the developing chamber 34b does not easily move from the auxiliary toner supply port 98 into the space 100, and the passage to the storage chamber 34a is more surely restricted, so that the toner is developed from the storage chamber 34a through the space 100. The toner conveyed to the chamber 34b is more reliably prevented from returning to the storage chamber 34a again. Therefore, the amount of toner carried on the developing roller 31 can be secured more reliably. As a result, it is possible to further reduce the decrease in image forming density.

The toner used in the developing cartridge 28 of the above-described embodiment is a polymerized toner as described above, and is a substantially spherical toner. For example, when a non-spherical angular toner such as a pulverized toner is used, if the toner is densely packed in the developing chamber 34b, it becomes difficult for the toner to flow,
Toner may accumulate and printing failure may occur. However, if the substantially spherical toner having good fluidity is filled in this way, the toner can flow well in the developing chamber 34b to stabilize the development and achieve good image formation. can do.

Further, since the laser printer 1 uses the non-magnetic one-component developing system, the developing roller 3
It is necessary to carry a fixed amount of toner that has been stably charged in No. 1, but as described above, this developing cartridge 2
In No. 8, it is possible to always secure a sufficient amount of toner in the developing chamber 34b, and as a result, the developing roller 31 can secure a fixed amount of toner and achieve good image formation.

Since the laser printer 1 is provided with the above-described developing cartridge 28, even if the toner is not sufficiently conveyed by the agitator 36, the initial image formation immediately after the start of use or the image after leaving for a while is left. Also in the formation, it is possible to effectively reduce the decrease in the image forming density, so that good image formation can always be achieved.

In the above-described embodiment, the toner supply port 37 is formed in a slit shape including the toner passage ports 62 which are elongated in the vertical direction and which are arranged in a line at predetermined intervals in the width direction. The shape of such a slit is not limited at all, and may be formed as a horizontally long slit, or a plurality of slit rows may be provided.

Further, the toner supply port 37 is not limited to be formed in the slit shape as described above, but may be formed in a wire mesh shape, or a brush-like member is provided in the opening. May be.

Further, in the developing cartridge 28 shown in FIG. 7 described above, the toner passage port 62 and the auxiliary toner passage port 99 are formed in substantially the same shape. However, these two openings are, for example, the toner passage port. 62 may be formed in different shapes such as a substantially rectangular shape that is long in the vertical direction and the auxiliary toner passage opening 99 is a substantially rectangular shape that is long in the width direction.

Although the shutter member 63 is used as the shielding member in the above-described embodiment, the shielding member of the present invention may be, for example, a seal member that covers the toner supply port 37 of the developing cartridge 28. In such a case, before the start of use, a seal member is attached to the toner supply port 37 to close the toner supply port 37, and when the developing cartridge 28 is attached to the laser printer 1, the seal is applied. The toner supply port 37 may be opened by peeling off the member from the toner supply port 37.
Further, as for the pressure release port, a seal member that covers the upper opening 80 may be provided as in the above.

Further, the pressing member 68 manually pulls up the handle portion 69 as shown in the above embodiment when the developing cartridge 28 is mounted on the laser printer 1. It may be configured such that it is automatically moved upward when it is mounted on 1.

In the above-described embodiment, the accommodating chamber 34a and the developing chamber 34b in the developing cartridge 28 are also used.
However, the accommodating chamber in the present invention is not limited to the above-described embodiment. It may be configured as possible.

[0151]

As described above, according to the invention described in claim 1, since the developer is filled in the developing chamber at a density higher than the loose apparent density, at the start of use, Sufficient developer is secured in the developing chamber. Therefore, even immediately after the start of use, the developer is sufficiently supplied to the developer carrier, and as a result, the amount of the developer carried on the developer carrier can be sufficiently secured, and the developer having the appropriate concentration can be obtained. An image can be formed.

According to the second aspect of the present invention, the developer is filled in the developing chamber at a rate of 2 g or more per 1 cm in the width direction orthogonal to the height direction. The developer is sufficiently secured, and the developer itself is sufficiently supplied to the developer carrier by the weight of the developer. Therefore, immediately after the start of use, the amount of the developer carried by the developer carrying member can be sufficiently secured, and an image having an appropriate density can be formed.

According to the third aspect of the present invention, with a simple structure, the developer can be filled in the developing chamber before the start of use and supplied from the storage chamber into the developing chamber after the start of use. Can be achieved.

According to the invention described in claim 4, it is possible to more reliably secure the amount of the developer carrier,
An image having an appropriate density can be formed.

According to the fifth aspect of the present invention, the developer carrying member is supplied with the reliably charged developer between the supply means and the developer carrying member, and stable development is achieved. The charge of the agent can be secured.

According to the sixth aspect of the invention, the developer can be reliably supplied to the developer carrier, and the amount of the developer carrier can be more reliably ensured and the developer can be supplied in an appropriate concentration. Image can be formed.

According to the seventh aspect of the present invention, the amount of developer supplied to the developer carrier immediately after the start of use can be reliably ensured, so that the amount of developer carrier carried can be more reliably achieved. Can be ensured and an image with an appropriate density can be formed.

According to the eighth aspect of the invention, the developer can be circulated in the developing chamber after the start of use, and as a result, better image formation can be achieved by stabilizing the charge. You can

According to the invention described in claim 9, it is possible to reliably secure the amount of the developer carried by the developer carrier at the start of use, and to promote the flow of the developer after the start of use. As a result, it is possible to achieve even better image formation by stabilizing the charging.

According to the tenth aspect of the invention, even if the developing device is densely packed before the start of use of the developing device, it flows well after the start of use of the developing device to stabilize charging. Therefore, good image formation can be achieved.

According to the eleventh aspect of the invention, it is possible to make the developer carrying member carry the reliably charged developer between the supplying means and the developer carrying member.

According to the twelfth aspect of the invention, in the non-magnetic one-component developing system, a sufficient amount of the developer can be secured in the developing chamber, so that the developer carrier can keep a constant carrying amount. It can be ensured and good image formation can be achieved.

According to the thirteenth aspect of the present invention, since the developer in the accommodating chamber can be conveyed toward the developing chamber while being stirred, excellent image formation can be achieved.

According to the fourteenth aspect of the present invention, an image having an appropriate density can be formed immediately after the use of the developing device is started.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part showing an embodiment of a laser printer as an image forming apparatus of the present invention.

FIG. 2 is a side sectional view of an essential part showing a process unit of the laser printer shown in FIG.

FIG. 3 is a side sectional view of a main part of a developing cartridge of the process unit shown in FIG. 2, in which (a) shows the developing cartridge in a state where a pressing member is pushed down in a state before use is started. , (B) show the developing cartridge with the pressing member pulled up in the steady state.

FIG. 4 is a cross-sectional view of the developing cartridge shown in FIG. 3 viewed from the direction of arrow M, in which (a) is a state in which the developing cartridge is mounted in the laser printer.
The shutter opening of the shutter member and the toner passage opening of the toner supply opening are aligned with each other, and the toner supply opening is opened. FIG. 6B shows the shutter member when the developing cartridge is not installed in the laser printer. Shutter opening of
The toner supply port does not coincide with the toner passage port, and the toner supply port is closed.

5 is an enlarged view of an essential part showing the toner supply port shown in FIG. 4, in which FIG. 5A shows the shutter port of the shutter member and the toner passage port of the toner supply port shown in FIG. Match and
The state where the toner supply port is opened is shown, (b) is
FIG. 4B shows a state in which the shutter opening of the shutter member and the toner passage opening of the toner supply opening do not coincide with each other and the toner supply opening is closed.

FIG. 6 is a side sectional view of an essential part showing another embodiment (a configuration in which an upper opening is provided in a partition wall between the developing chamber and the containing chamber) of the developing cartridge of the process unit shown in FIG. In addition, (a) shows the developing cartridge in a state in which the upper opening is closed before the start of use,
(B) shows the developing cartridge in a state where the upper opening is opened in the steady state.

FIG. 7 is a side sectional view of an essential part showing another embodiment of the developing cartridge of the process unit shown in FIG. 2 (a mode in which a partition wall and an auxiliary partition wall are provided between the developing chamber and the containing chamber).

[Explanation of symbols]

1 laser printer 28 Development Cartridge 31 developing roller 32 layer thickness control blade 33 Supply roller 34a accommodation room 34b Development room 36 Agitator 37 Toner supply port 63 Shutter member 68 Pressing member 80 Upper opening

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Claims (14)

[Claims] 1. A storage chamber for storing a developer, and a development chamber in which a developer carrier is provided, wherein the storage chamber and the development chamber are provided between the storage chamber and the development chamber. In a developing device in which an opening communicating with the developing device is formed, before the use of the developing device is started, the opening is
A shielding member that prohibits the passage of the developer between the storage chamber and the developing chamber is provided, and the developing chamber is filled with the developer at a density higher than the loose apparent density. Characterizing development device. 2. An accommodating chamber for accommodating a developer and a developing chamber in which a developer carrier is provided, wherein the accommodating chamber and the developing chamber are provided between the accommodating chamber and the developing chamber. In a developing device in which an opening communicating with the developing device is formed, before the use of the developing device is started, the opening is
A shielding member that prohibits the passage of the developer between the storage chamber and the developing chamber is provided, and the developing chamber is filled with the developer at a rate of 2 g or more per cm in a width direction orthogonal to the height direction. And a developing device. 3. The shielding member is provided so that the opening can be opened and closed.
The developing device according to 1. 4. In the developing chamber, a supply means for supplying the developer to the developer carrying member is provided with a gravity of the developer in the developing chamber so that the gravity of the developer in the developing chamber acts. The developing device according to claim 1, wherein the developing device is disposed downward in the direction. 5. The developing chamber is provided with a layer thickness regulating member for causing the developer carrying member to carry the developer in a thin layer, and the developer carrying member is provided in the developing chamber within the developing chamber. Arranged laterally in the direction of gravity of the developer in the developing chamber, the layer thickness regulating member, the gravity of the developer in the developing chamber,
5. The developing device according to claim 4, wherein the developing device is arranged between the developer and the developer carrier so as to limit the direct action on the developer carrier. 6. The height of the developer in the developing chamber is 25 m from the supply means before the use of the developing device is started.
The developing device according to claim 4 or 5, wherein the developing device has a thickness of m or more. 7. The developing device according to claim 1, wherein the developing chamber is provided with pressing means for pressing the developer toward the supply means. 8. The developing device according to claim 7, wherein the pressing unit is configured to release the pressing force. 9. A pressure release port for releasing the filling pressure of the developer is provided above the opening between the accommodating chamber and the developing chamber. 6. The developing device according to any one of 1 to 5. 10. The developing device according to claim 1, wherein the developer is a substantially spherical toner. 11. The developing device according to claim 4, wherein the supply unit is in contact with the developer carrying member. 12. The developing device according to claim 1, which is a non-magnetic one-component developing system. 13. The carrying means for carrying the developer toward the developing chamber through the opening in the storage chamber is provided.
The developing device according to any one of 1. 14. An image forming apparatus, comprising the developing device according to claim 1. Description: