JPH07261549A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a developing roller from being left with the shape trace of the tip of a regulating member during the nonoperational state of the developing roller over a long period. CONSTITUTION:This developing device is constituted of a developing roller 243 sticking a one-constituent nonmagnetic toner 241 to a photoreceptor drum 22 via the rotating action for development, a feeding roller 244 feeding the toner 241 in a toner hopper 242 to the developing roller 243 via rotation, a rotatable support shaft 246, a regulating member 247 fixed to the support shaft 246 at the rear end section in contact with the developing roller 243 at the tip section and regulating the toner quantity stuck to the photoreceptor drum 22, a circular member fixed to the rotary shaft of the developing roller 243, and a fixed member 37 fixed to one end of the support shaft 246 and kept in contact with the outer periphery of the circular member on the periphery. The support shaft 246 is arranged in the downstream of the rotating direction of the developing roller 243 against the tip section of the regulating member 247.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an electrophotographic image recording apparatus applied to a laser printer or the like, and applies a one-component non-magnetic toner to an electrostatic latent image formed on an electrostatic latent image holder. The present invention relates to a developing device that adheres and develops.

[0002]

2. Description of the Related Art An electrophotographic image recording apparatus using this type of developing apparatus is disclosed, for example, in Japanese Patent Laid-Open No. 5-1158.
No. 8 publication is known. As shown in FIG. 7, the photosensitive drum 1 serving as an electrostatic latent image holder is provided with a charging surface for the photosensitive surface of the photosensitive drum 1.
The laser beam scanning unit 3 forms an electrostatic latent image on the charged photosensitive surface based on the recorded information, and the one-component non-magnetic toner from the developing device 4 is attached to the electrostatic latent image for development. Then, a toner image is formed.

Subsequently, the toner image is transferred onto the recording paper 6 by the transfer device 5.
Then, the recording sheet 6 is discharged by the static eliminator 7 to facilitate the separation of the recording sheet 6 from the photosensitive drum 1. Then, the recording paper 6 on which the toner image is transferred is thermally fixed by the thermal fixing device 8 and discharged to the outside.

Residual toner remaining on the photosensitive drum 1 is scraped by a toner scraping blade 9 and stored in a toner storage container 10. After that, the photoconductor drum 1 is removed from the static elimination lamp 11
Is discharged by.

The developing device 4 includes a container 4a containing one-component non-magnetic toner, a developing roller 4b which contacts the photosensitive drum 1 and adheres the toner to the photosensitive drum 1, and a toner which supplies toner to the developing roller 4b. The supply roller 4c and the developing roller 4b are composed of a layer thickness regulating member 4d that regulates the thickness of the toner layer to be constant. The layer thickness regulating member 4d is composed of a leaf spring member, is rotatably supported by the shaft 4f, has its tip in contact with the peripheral surface of the developing roller 4b, and presses the other end with a coil spring 4e, whereby the tip is The peripheral surface of the developing roller 4b is contacted with an appropriate pressing force.

[0006]

However, in the case where the coil spring 4e is used to press the tip of the layer thickness regulating member 4d against the peripheral surface of the developing roller 4b as described above, the coil spring 4e is operated or not operated. Regardless of this, the tip of the layer thickness regulating member 4d is always pressed against the peripheral surface of the developing roller 4b. The developing roller 4b is usually made of a rubber material such as urethane, NBR, or EPDM. Therefore, if the tip of the layer thickness regulating member 4d is constantly in pressure contact with the peripheral surface of the developing roller 4b, the apparatus is not used, that is, If the non-operating state lasts for a long period of time, there is a problem that due to the compression set of rubber, a shape mark of the tip of the layer thickness regulating member 4d remains on the peripheral surface of the developing roller 4b.

This shape mark remains as a development mark at the time of recording an image, which hinders image recording.

Therefore, the present invention provides a developing device in which there is no possibility that the shape trace of the tip of the regulating member will remain on the developing roller even when the developing roller is not operating for a long period of time.

[0009]

The invention according to claim 1 is
A developing roller that develops by attaching one-component non-magnetic toner to the electrostatic latent image holder by a rotating operation, a supply roller that supplies toner in the toner storage tank to the developing roller by a rotating operation, and a rotatable support shaft. While fixing the rear end to this support shaft, the toner supplied from the supply roller to the developing roller comes into contact with the developing roller at its front end before reaching the electrostatic latent image holding member, and the developing roller causes electrostatic discharge. It consists of a regulating member that regulates the amount of toner attached to the latent image carrier,
The support shaft is arranged on the downstream side in the rotation direction of the developing roller with respect to the tip of the regulating member.

According to a second aspect of the present invention, a developing roller that develops by attaching one-component non-magnetic toner to the electrostatic latent image holding member by a rotation operation, and a toner in a toner storage tank is supplied to the developing roller by rotation. The supply roller, the rotatable support shaft, and the rear end portion fixed to the support shaft, and the front end of the developing roller before the toner supplied from the supply roller to the developing roller reaches the electrostatic latent image holding member. Part that comes into contact with the developing roller and restricts the amount of toner that adheres to the electrostatic latent image holder from the developing roller, a circular member with a circular outer periphery that is fixed to the rotating shaft of the developing roller, and is fixed to one end of the support shaft. In addition, the support member is composed of a fixed member whose peripheral surface is in contact with the outer peripheral surface of the circular member, and the support shaft is arranged downstream of the tip of the regulating member in the rotation direction of the developing roller.

[0011]

In the invention according to claim 1, the tip end portion of the regulation member rotates about the support shaft, and the support shaft is arranged downstream of the tip end portion of the regulation member in the rotation direction of the developing roller. Therefore, the tip of the regulating member is pressed against the developing roller by its own weight. When the developing roller rotates, the tip of the regulating member is pressed in the rotating direction of the developing roller due to friction with the developing roller, but the pressing force is supported by the support shaft.

In this way, the regulating member reliably regulates the amount of toner adhered from the developing roller to the electrostatic latent image holder.

According to the second aspect of the invention, when the developing roller is stopped, the tip of the regulating member is pressed against the developing roller by its own weight.

When the developing roller rotates, the circular member rotates, and the circular member tries to rotate the fixed member by the contact frictional force. As a result, the rotating force of the fixed member is transmitted to the restriction member via the support shaft. However, since the tip of the regulating member is in contact with the developing roller, the rotation of the fixed member is regulated.

Thus, when the developing roller is rotated, the tip of the regulating member is pressed against the developing roller with a strong pressing force by receiving the rotating force of the fixed member.

In this way, the regulating member reliably regulates the amount of toner adhered from the developing roller to the electrostatic latent image holding member.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a laser printer of the present invention will be described.

In FIG. 1, reference numeral 21 denotes an apparatus main body, and a photosensitive drum 22 which is an electrostatic latent image holding member is arranged at the center of the apparatus main body 21. The photosensitive drum 22 is configured to rotate clockwise as indicated by an arrow in the drawing during a printing operation.

A charger 23 is arranged above the photosensitive drum 22 and a developing device 24, a transfer device 25, a charge eliminator 26, a cleaning device 27, and a charge eliminator 28 are provided clockwise from the charger 23. They are arranged in order.

A laser scanning unit 29 is arranged above the charger 23, and scanning laser light P from the laser scanning unit 29 is passed through the space between the charger 23 and the developing device 24 to the photoconductor drum 22. Irradiation and exposure are performed.

A paper feed cassette 30 is provided at the end of the apparatus main body 21 on the side where the developing device 24 is provided. The paper feeding cassette 30 stores the recording papers 31 in a stacked manner, and feeds the recording papers 31 one by one between the photosensitive drum 22 and the transfer device 25 by the operation of the paper feeding roller 32 and the conveying roller 33 during printing. It is like this.

A manual feed tray 34 for manually feeding the recording paper is arranged on the paper feed cassette 30.

A heat fixing device 35 is arranged on the side of the apparatus main body 21 opposite to the side on which the paper feeding cassette 30 is provided, and the recording paper on which the image transfer is completed is thermally fixed and discharged.

This device uses the photosensitive drum 22 during printing.
Is rotated to uniformly charge the photosensitive surface with the charger 23, and the charged photosensitive surface is irradiated with the scanning laser light P from the laser scanning unit 29 to record an image as an electrostatic latent image. The image is developed with a one-component non-magnetic toner from the developing device 24 to form a toner image. Then, the toner image is transferred to the transfer device 25.
Then, the recording paper 31 is transferred to the recording paper 31, the charge is removed by the static eliminator 26 to separate it from the photoconductor drum 22, and the separated recording paper 31 is thermally fixed by the thermal fixing device 35 and discharged.

The toner remaining on the photosensitive drum 22 is cleaned by the cleaning device 27, and then the surface of the photosensitive drum 22 is discharged by the discharging lamp 28 to prepare for the next charging. The printing operation is performed by repeating the above operation.

The developing device 24, as shown in FIG.
A toner hopper 242, which is a toner storage tank that stores the one-component non-magnetic toner 241, a developing roller 243 that is provided outside the toner hopper 242 and is in contact with the photoconductor drum 22, and the toner hopper 2 on the developing roller 243.
Toner supply roller 244 for supplying one-component non-magnetic toner 241 in 42, and toner 2 in the toner hopper 242.
Agitating roller 245 for agitating 41, and the developing roller 24
3 is constituted by an L-shaped restricting member 247 in which the front end portion is pressed against the outer peripheral surface of 3, and the rear end portion is fixed to a support shaft 246 which is a rotatable shaft.

The developing roller 243 and the toner supply roller 244 are adapted to rotate in the counterclockwise direction opposite to the direction of rotation of the photosensitive drum 22, as indicated by the arrow in the figure.

The support shaft 246 is connected to the developing roller 24.
3, and is arranged on the downstream side in the rotation direction of the developing roller 243 with respect to the tip of the regulating member 247. The tip of the regulating member 247 is the developing roller 24.
3 is in contact with the outer peripheral surface of the developing roller 243 at a portion located slightly upstream of the center position of the developing roller 243.

The developing roller 243 is made of an elastic, conductive, non-magnetic (or non-magnetized) member,
Around the conductive shaft 243a, which is a rotating shaft, conductive carbon particles, metal particles, metal fibers, etc. are dispersed in urethane rubber, silicon rubber, ethylene propylene rubber, NBR, chloroprene rubber, butyl rubber, etc. Of 10 ¹⁰ Ω · cm or less is formed, and the conductive rubber layer is covered with a silicone resin, a urethane resin, a fluororesin or the like.

In this embodiment, the conductive rubber layer has a hardness of 30.
It is made of urethane rubber and the surface is coated with conductive urethane paint. The resistance value between the conductive shaft 243a and the coating film of the conductive urethane paint is set to 10 ⁶ Ω · cm or less.

The outer diameter of the conductive shaft 243a is 8 m.
m, the outer diameter of the rubber roller is 18 mm, and the film thickness of the conductive urethane coating film is 20 to 200 μm.

Conductive shaft 2 of the developing roller 243
A negative bias is applied to 43a.

It should be noted that the developing roller need not have a coating material such as silicone resin, urethane resin, or fluororesin. Further, even if the developing roller is constructed by coating the surface of a high resistance or insulating rubber roller with a conductive resin, the surface of the semiconductor rubber roller is provided with microelectrodes electrically insulated from each other. May be.

As a method of adhering the toner from the developing roller 243 to the photosensitive drum 22, the outer peripheral surface of the developing roller 243 is brought into non-contact with the photosensitive surface of the photosensitive drum 22, and the toner particles are caused to fly by the developing electric field. Method,
A method in which the outer peripheral surface of the developing roller 243 is brought into contact with the photosensitive surface of the photosensitive drum 22 so that the toner is attached by rolling or sliding, and a DC electric field is formed between the developing roller 243 and the photosensitive drum 22 to form the toner. And a method of forming an AC electric field between the developing roller 243 and the photoconductor drum 22 to attach the toner. Either method can be applied, but in the present embodiment, a method is used in which the developing roller 243 is brought into contact with the photosensitive drum 22 and toner is attached thereto.

The one-component non-magnetic toner 241 includes
92 parts by weight of polyester resin, copper phthalocyanine pigment 4
Parts by weight, low molecular weight polypropylene 2 parts by weight, metal-containing dye 2
A negatively chargeable toner having a volume average particle diameter of 10 μm and comprising 0.5 part by weight of silica and 0.5 part by weight of external additive silica is used.

The regulating member 247 has a tip portion made of a hard or soft resin such as acrylic resin, urethane resin, fluororesin, polyamide resin, silicon resin, melanin resin, polystyrene resin, polyester resin, epoxy resin, or the like. Composite or urethane rubber,
It is made of an elastic material such as silicon rubber, and its tip is L
It is supported by a character-shaped support member.

The rear end portion of the regulating member 247, that is, the rear end portion of the support member is fixed to the peripheral surface of the support shaft 246 by screws 247a as shown in FIG.

As shown in FIG. 4, a circular member 36 having a circular outer periphery is fixed to one end of the conductive shaft 243a of the developing roller 243, and one end of the support shaft 246 is attached to the outer peripheral surface of the circular member 36. A fixing member 37 having a circular outer periphery that is in contact with the surface is fixed.

The circular member 36 and the fixing member 37 are made of resin such as ABS, PE, PP, POM and PC.

Since the fixing member 37 does not rotate, the outer circumference does not necessarily have to be circular, and only the contact portion with the circular member 36 needs to be circular, and thus may be fan-shaped.

Further, the fixing member 37 and the circular member 36 may have only one end of the developing roller 243 of the developing device 24 as described above, but the pressing force of the regulating member 247 is more stably applied to the surface of the developing roller 243. It may be arranged at both ends of the developing roller 243 for giving.

In the embodiment having such a structure, the developing device 24 forms the one-component non-magnetic toner 241 on the electrostatic latent image formed on the photosensitive surface of the photosensitive drum 22 at the time of printing to develop the electrostatic latent image.

In the developing device 24, the toner supply roller 244
Rotates to convey the toner 241 in the toner hopper 242 onto the peripheral surface of the developing roller 243. The toner 241 is primarily charged and attached on the peripheral surface of the developing roller 243 at the contact portion with the developing roller 243. Toner 2 that is attached with the primary charge
41 is the photosensitive drum 22 by the rotation of the developing roller 243.
While being conveyed to, the toner is secondarily charged and attached due to friction with the tip portion of the regulating member 247 and formed into a layer having a constant thickness.

When the developing roller 243 rotates, the circular member 36 also rotates. However, since the tip end of the regulating member 247 of the support shaft 246 is in contact with the developing roller 243, the fixing member 37 is in contact with the circular member 36. But it doesn't rotate. That is, the fixed member 37 receives the rotational frictional force of the circular member 36, but slides on the outer peripheral surface of the circular member 36.

The rotational frictional force from the circular member 36 is applied to the support shaft 2
An attempt is made to rotate 46, and the force is transmitted to the tip portion of the regulation member 247.

When the developing roller 243 rotates in this way,
The pressing force applied to the developing roller 243 by the tip of the regulating member 247 increases, and the developing roller 24 at the tip of the regulating member 247 increases.
The pressure contact force with respect to 3 becomes large.

As the developing roller 243 rotates in this manner, the developing roller 243 at the tip of the regulating member 247.
Since the pressure contact force with respect to is increased, the same action and effect as when the restriction member 247 is biased by using a spring can be obtained. Therefore, the amount of toner conveyed from the developing roller 243 to the photosensitive drum 22 can be regulated to be constant, and the thickness of the toner layer can be controlled to be constant.

Further, since the developing roller 243 does not rotate during non-printing, the leading end of the regulating member 247 has the developing roller 2
It is pressed against 43 only by its own weight. Since this pressure contact force is sufficiently weaker than when the developing roller 243 is rotated, even if the developing roller 243 is in a non-printing state for a long period of time, no trace of the shape of the tip of the regulating member 247 is left on the surface of the developing roller 243.
Therefore, the compression set does not occur on the surface of the developing roller 243, and the image quality at the time of printing is not deteriorated thereby. Also, the spring can be eliminated. As shown in FIG. 5, the diameter of the circular member 36 is the same as the diameter of the developing roller 243, and the distance from the center B of the support shaft 246 to the contact point A where the fixing member 37 contacts the circular member 36 is l, The distance from the center B of the support shaft 246 to the contact point C where the tip of the regulating member 247 is in contact with the developing roller 243 is L,
The angle between the horizontal line and the straight line passing through the center B of the support shaft 246 and the contact point C is θ, the contact force between the circular member 36 and the fixed member 37 is mg, the dynamic frictional force at that time is μmg, and the rotation of the developing roller 243. If the speed is v, the acting force N at the contact point C where the tip of the regulating member 247 is in contact with the developing roller 243 is N = 1 / L · μmg because of the moment.

When this acting force N is rewritten by the vertical component F, F = N cos θ = 1 / L · μmg · cos θ.

Between the regulating member 247 and the developing roller 243,
The contact pressure P per cm in the developing roller width direction is 30 g.
Since the range of / cm <P <100 g / cm is the best, assuming that the width of the developing roller 243 is 22 cm, the vertical component F of the entire width is 0.66 Kg <F <2.2 Kg, and F = 1 / L. From the relationship of μmg · cos θ, 0.66 Kg <1 / L · μmg · cos θ <2.2 Kg.

Therefore, the force acting on the regulating member 247 is
It can be obtained by arbitrarily setting l, L, μ, mg and θ. The contact force mg between the circular member 36 and the fixing member 37 is preferably about 5 kg, for example.

Further, for example, 1 / L = 0.5, mg = 5K
When g, θ = 30 °, that is, cos θ = 0.866, the fixing member 37 and the circular member 36 should be selected from materials satisfying the friction coefficient μ of about 0.3 <μ <1.0. become.

Incidentally, in the above embodiment, the developing roller 2
Although the rotational frictional force between the circular member 36 and the fixed member 37 is applied to the tip end portion of the regulation member 247 when the 43 is rotated,
For example, the circular member 36 and the fixing member 37 may not be used, and the tip end of the restricting member 247 may be in pressure contact with the developing roller 243 even when the developing roller 243 is rotated. Even if the developing roller 243 rotates in this way as well, since the regulating member 247 is supported by the support shaft 246, the frictional force between the developing roller 243 and the tip of the regulating member 247 becomes sufficiently large, and the toner due to the regulating member 247 becomes large. The effect of controlling the amount and the toner layer thickness is sufficiently obtained.

In the above embodiment, the shaft is used as the support shaft, and the rear end of the L-shaped regulating member is screwed to the shaft. However, the present invention is not limited to this. As shown, support shafts 256a and 256b may be attached to both side surfaces of the regulation member 257 to integrally form the regulation member and the support shaft.

Although the present invention has been described in the case of using the present invention in a laser printer, the present invention is not necessarily limited to this, and other image recording apparatus such as a printer or a copying machine using an LED or EL element for exposure. Can also be used for

[0056]

As described above, according to the present invention, there is no possibility that the shape trace of the tip of the regulating member will remain on the developing roller even when the developing roller is not operating for a long period of time. Thus, it is possible to provide a developing device that can always perform image recording with good image quality without the influence of the shape trace affecting the development and deteriorating the recorded image.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a laser printer showing an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a developing device of the embodiment.

FIG. 3 is a perspective view showing the outer appearance of the developing device according to the embodiment.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a view for explaining the action of the restriction member of the same embodiment.

FIG. 6 is a perspective view showing another embodiment of the regulating member and the support shaft.

FIG. 7 is a diagram showing a configuration example of a conventional developing device.

[Explanation of symbols]

 22 ... Photosensitive drum (electrostatic latent image holder) 24 ... Developing device 242 ... Toner hopper 243 ... Developing roller 246 ... Support shaft 247 ... Regulation member

Claims (2)

[Claims] 1. A developing roller for developing a toner by adhering one-component non-magnetic toner to an electrostatic latent image carrier by a rotating operation, and a supply roller for supplying toner in a toner storage tank to the developing roller by a rotating operation. A rotatable support shaft and a rear end portion fixed to the support shaft, and a front end portion of the developing roller before the toner supplied from the supply roller to the developing roller reaches the electrostatic latent image holding member. And a regulation member that regulates the amount of toner adhered to the electrostatic latent image holding member from the developing roller, and the support shaft is in the rotational direction of the developing roller with respect to the tip of the regulation member. A developing device arranged on the downstream side. 2. A developing roller for developing a toner by adhering one-component non-magnetic toner to the electrostatic latent image carrier by a rotating operation, and a supply roller for supplying the toner in the toner storage tank to the developing roller by rotation. The rotatable support shaft and the rear end portion are fixed to the support shaft, and the front end portion is attached to the developing roller before the toner supplied from the supply roller to the developing roller reaches the electrostatic latent image holding member. A restricting member that restricts the amount of toner that comes into contact with the electrostatic latent image holding member from the developing roller, a circular member having a circular outer periphery fixed to the rotating shaft of the developing roller, and one end of the supporting shaft. A fixed member which is fixed and whose peripheral surface is in contact with the outer peripheral surface of the circular member, wherein the support shaft is arranged on the downstream side in the rotational direction of the developing roller with respect to the tip of the regulating member. Development Location.