JPH08300714A - Image forming apparatus - Google Patents

Abstract

PURPOSE: To form a thin and uniform toner layer on a toner carrier and to obtain an excellent quality of image with no fluctuation of density and formation of a stable image. CONSTITUTION: A toner layer restricting member 18 in this image forming apparatus is constituted of a rod-like body 18b consisting of a stainless round rod extending in the direction intersecting the toner carrying direction by right angles and an elastic sheet 18a consisting of a stainless spring steel one end of which is fixed on the rod-like body 18b and pushing the rod-like body 18b toward a toner carrying roller 14. Hereby, the rod-like body 18b itself can be alone processed with extremely good accuracy and especially the surface shape and condition can be uniformly and smoothy finished. Therefore, a thin and uniform toner 16 layer can be formed on the surface of a toner carrying body 14 and it is possible to stably record an image with high quality without fluctuation of density and fog.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applied to a copying machine, a printer, a facsimile and the like.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses of this type, as disclosed in, for example, Japanese Patent Laid-Open No. 6-155798, an image is formed on an aperture electrode body having a plurality of small openings (apertures). An image that controls the passage of apertures of toner particles (charged particles) charged to a predetermined polarity by applying a drive signal by a signal and records an image on a medium such as print paper by the passed toner particles. Forming devices have been proposed.

In this image forming apparatus, an aperture electrode body (electric field control means) made of an insulating sheet in which a plurality of openings (apertures) are arranged in a row is provided, and one side of the aperture electrode body is a circumference of a toner carrying roller (toner carrying body). While being arranged so as to face the surface, the surface of the aperture electrode body opposite to the toner carrying roller, that is, the surface facing the recording medium,
A control electrode for controlling passage of charged toner (charged particles) through the opening is separately installed for each opening, and a rear electrode roller (counter electrode) to which a voltage of a predetermined polarity is applied.
Is arranged so as to contact the back surface side of the recording medium, and the toner pulled out from the opening is caused to fly toward the surface of the recording medium by electrostatic force.

According to this image forming apparatus, since the electric field generated by the control electrode is formed between the control electrode and the inside of the opening, and between the opening and the toner carrying surface of the toner carrying roller facing the opening, the electric field is carried. The control electric field can be applied directly to the toner to be controlled, so that the control efficiency is good, and a part of the supplied toner receives mechanical force due to the contact with the aperture electrode body, and the opening corresponding to the non-image area is opened. Even if you enter the department,
Since the electric field inside the opening can be controlled so as not to pass through the opening, the toner controllability is also good. Therefore, a high quality image can be easily obtained. Furthermore, since the toner carrying roller and the aperture electrode body are opposed to each other with the toner layer interposed therebetween, they can be arranged at a relatively short distance, and the toner flow can be accurately controlled even with a low control voltage. it can. Therefore, excellent effects such as low cost and high reliability can be expected without the need for expensive control drive elements.

However, in the above-mentioned conventional image forming apparatus, for example, as shown in FIG. 13, a toner layer regulating blade 118 made of a metal elastic plate or the like is used, and its flat surface is the surface of the toner carrying roller 114. The toner carrying roller 114 is arranged so as to come into pressure contact with the pressure contact force.
Since a uniform toner layer is formed on the surface of the toner, a corresponding effect is obtained in that the thickness of the layer of the toner 116 is uniformly regulated, but the function as a charging blade, that is, the thickness of the toner layer is obtained. It was not possible to sufficiently exert the function of restricting the toner to be thinner and giving a predetermined amount of electric charge to all the toner particles.

Therefore, in order to solve this problem, FIG.
As shown in FIG. 4 and FIG. 15, a laterally elongated elastic metal plate, for example, an elastic metal blade 128 made of stainless spring steel or the like having a thickness of about 0.1 mm is bent at a tip of about R 0.2 mm. An apparatus has been proposed in which the outer side of the bent portion is pressed against the toner carrying roller 114 to realize a thin layer of the toner 116.

[0007]

However, in the elastic metal blade 128 described above, if the shape and size of the R portion of the bend are not uniform in the longitudinal direction, a thin layer toner is formed on the carrier roller (toner carrier). Since the layer thickness becomes uneven, the bending portion is required to be as small and uniform as possible, but due to the processing principle, minute cracks inevitably occur in the bending direction. Also, from the consideration of the strength and processing stability of the blade, it is necessary to match the bending direction with the rolling direction of the material, but in that case, scratches on the unevenness extending in the rolling direction that can be inevitably made during roll forming of the material , It will be attached in the bending direction of the blade.

In the worst case, the fine cracks generated in the blade in the direction of the toner carrying of the carrier and the scratches during the roll forming immediately become uneven in the thickness of the toner layer of the carrier. Also, cracks and scratches are relatively small,
Even if there is no problem at the beginning of use, the toner will be scratched and damaged due to uneven pressure applied to the toner layer, etc. However, the thickness of the toner layer becomes uneven due to this.

As described above, when the image is formed with the toner layer thickness uneven in the longitudinal direction of the carrier or the surface is uneven, not only density unevenness occurs but also image fogging is caused. Become.

The present invention has been made in order to solve such a problem, and it is possible to easily form a thin and uniform toner layer, and to obtain excellent image quality without density unevenness and stable image quality. An object is to provide an image forming apparatus capable of forming an image.

[0011]

In order to achieve this object, the toner layer regulating member in the image forming apparatus of the present invention has a rod-shaped body extending in the direction orthogonal to the toner transport direction, and one end of the rod-shaped body. It is characterized by comprising an elastic plate which is fixed and presses the rod-shaped body toward the toner carrier.

Further, the rod-shaped body is made of a round rod made of metal such as stainless steel or aluminum.

Further, the elastic plate is characterized by being made of a spring metal material such as stainless spring steel or phosphor bronze.

Further, it is characterized in that an image is formed by directly controlling the flow of the toner carried by the toner carrier by the electric field control means.

[0015]

According to the image forming apparatus of the present invention having the above-mentioned structure, the toner layer regulating member is a rod-shaped member extending in the direction orthogonal to the toner conveying direction, and one end of which is fixed to the rod-shaped member. Is constituted by an elastic plate that presses the toner toward the toner carrier, the rod itself can be processed by itself with extremely high precision, and in particular, its surface shape can be finished uniformly and smoothly. Therefore, a thin and uniform toner layer can be formed on the surface of the toner carrier, and excellent image quality without density unevenness and stable image formation are possible.

Further, since the rod-shaped body is made of a round rod made of metal such as stainless steel or aluminum, it can be easily and accurately performed according to, for example, a manufacturing method of a wire dot used in an impact type dot printer. It can be processed.

Furthermore, since the elastic plate is made of a spring metal material such as stainless spring steel or phosphor bronze, it is possible to easily form a metal rod-like body by using a general joining means such as welding or brazing. In addition, it is possible to securely fix the elastic member, and the elastic force can be evenly applied to each part in the longitudinal direction of the rod-shaped body. Therefore, the rod-shaped body can be pressed against the surface of the toner carrier under the same conditions anywhere in the longitudinal direction, and a thin and uniform toner layer can be formed.

Further, since the flow of the toner carried by the toner carrier is directly controlled by the electric field control means, a thin and uniform toner layer is used to form a high quality image without density unevenness. It can be stably formed.

[0019]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus embodying the present invention. A toner supplying device 10 is provided on the right side of the image forming device, and a toner supplying device 10 is provided on the left side of the toner supplying device 10.
An aperture electrode body 1 is provided as an electric field control means (toner flow control means) for controlling the toner flow. On the left side of the aperture electrode body 1, a back electrode plate 22 as a counter electrode is arranged with a space of 1 mm. Further, the recording medium 20 is conveyed in the direction of arrow C by the rotation of the conveying roller 19 or the like into the gap between the aperture electrode body 1 and the back electrode plate 22, and the destination of the conveyance is a pressure roller having silicon rubber on the surface layer. A heat fixing device 26 including a heat roller 26b having a halogen heater inside is provided. In addition, this heat fixing device 2
No. 6 can be replaced by either a heat fixing method or a pressure fixing method.

Next, the details of the above respective components will be described. First, as shown in FIG. 1, the toner supply device 10 includes a toner case 1 which also serves as a housing of the entire device.
1, a toner, preferably an insulating toner 16 is stored in the toner case 11, and a cylindrical toner carrying roller (for carrying the toner 16 and carrying it toward the aperture electrode body 1 ( Toner carrier) 1
4 is provided so as to be rotatable in the arrow B direction shown in FIG. Further, in the lower right portion of the toner carrying roller 14,
A cylindrical supply roller 12 for supplying the toner 16 stored in the toner case 11 to the toner carrying roller 14 is provided rotatably in the arrow direction shown in FIG. The supply roller 12 and the toner carrying roller 14 are arranged parallel to each other so that the generatrixes of their cylindrical surfaces are in contact with each other.

Further, in the toner case 11, above the toner carrying roller 14, the carrying roller 14 is provided.
The toner also functions as a charging blade for adjusting the amount of the toner 16 carried by the roller 16 to be uniform on the roller surface and for uniformly charging the toner 16 to a predetermined polarity, here negative polarity (negative). Layer control blade 18
Is provided. The toner agitator 17 for stirring toner
Is for agitating the toner 16 contained in the toner case 11, and is rotatably provided in the direction of the arrow shown in FIG.

As shown in detail in FIG. 2, the aperture electrode body 1 is composed of, for example, a polyimide insulating sheet 2 having a thickness of about 25 μm, and the insulating sheet 2 has a diameter of about 60 μm. Multiple openings (aperture)
6 are formed in a line in the longitudinal direction of the aperture electrode body 1. Around the opening 6, a control electrode 4 made of copper foil having a thickness of about 8 μm is formed for each opening 6.

Here, the positional relationship between the opening 6 of the aperture electrode body 1 and the toner carrying roller 14 will be described in detail. As shown in FIG. 1, each opening (aperture) 6 will be described.
Are arranged so that their respective center lines pass through the leftmost portion of the peripheral surface of the toner carrying roller 14 and the central axis of the toner carrying roller 14. According to this, the openings 6 are evenly arranged vertically with respect to the leftmost portion of the peripheral surface of the toner carrying roller 14, so that the distribution of the toner 16 passing through the openings 6 is changed. The entire area of the (aperture) 6 can be made uniform. Further, since the wall surface of the opening 6 and the flying direction of the toner 16 are parallel to each other, it is possible to stably fly the toner.

Further, the aperture electrode body 1 itself bends with respect to the toner carrying roller 14 by the same angle (about 3 degrees) between the upstream side and the downstream side in the transport direction of the recording medium 20 around the opening 6. Being pressed against. This allows
Since the contact area between the aperture electrode body 1 and the toner carrying roller 14 can be increased and the periphery of the opening 6 can be pressed uniformly, the occurrence of toner density unevenness can be suppressed as much as possible. .

A control voltage applying circuit 8 is connected between the control electrode 4 and the toner carrying roller 14.
Based on the image signal, the control voltage applying circuit 8 applies a positive voltage of about +30 V to the control electrode 4 corresponding to the image portion and −30 V to the control electrode 4 corresponding to the non-image portion.
It is configured to apply a negative voltage of about V. On the other hand, a backside voltage application circuit 24 composed of a DC high voltage power supply is connected between the backside electrode plate 22 and the toner carrying roller 14, and a high voltage of about +1 kV can be applied to the backside electrode plate 22. It is like this.

By the way, the toner layer regulating blade 18 in the present embodiment, as shown in detail in FIG. 3 and FIG.
For example, at one end of a horizontally elongated elastic plate 18a made of a metal material for spring having a thickness of about 0.1 mm, a rod-shaped body made of stainless steel having a diameter of about 0.5 mm, or a round bar made of metal such as free-cutting steel or aluminum ( The pressure contact rod) 18b is integrally joined. The pressure contact rod 18b is pressed against the surface of the toner carrying roller 14 in a state of being arranged in parallel with the central axis of the toner carrying roller 14, that is, in a state of extending in a direction orthogonal to the conveying direction of the toner 16. Therefore, the base end portion of the elastic plate 18a is attached to the toner case 11.

The metal material for springs used as the material of the elastic plate 18a includes, for example, spring steel, which is very general as an iron-based material, and stainless spring steel, and a copper-based material. As, phosphor bronze, nickel silver,
Alternatively, there are beryllium copper and the like, but stainless spring steel, which is particularly excellent in rust resistance, is preferably used here. Further, stainless spring steel is also preferably used for the rod-shaped body 18b.

Here, the rod-shaped body 18b itself can be processed very easily and accurately according to a method of manufacturing a wire dot or the like used in an impact type dot printer. In particular, since polishing can be performed by itself, the surface shape can be finished extremely uniformly and smoothly.

Then, the rod-like body 18b and the elastic plate 18
A general joining method such as welding or brazing can be adopted for joining the a and the rod-shaped body 18b and the elastic plate 18a.
Apply a type of adhesive that is suitable for bonding materials with
It is also possible to bond both.

At this time, it is needless to say that the rod-shaped body 18b may be joined while the cross section remains circular as shown in FIG. 4, but if possible, the joining is made stronger. As shown in FIG. 5, the rod-shaped body 1
A part of the outer peripheral surface of 8b may be processed to be flat, and one end of the elastic plate 18a may be joined to the flat surface.
As shown in FIG. 6, a groove may be formed in a part of the outer peripheral surface of the rod-shaped body 18b, and one end of the elastic plate 18a may be inserted into and joined to this, or may be press-fitted. In particular, according to the method shown in FIG. 6, it is possible to perform accurate joining without using a special positioning jig or the like.

Next, the operation of the image forming apparatus configured as described above will be described.

First, when the supply roller 12 rotates in the direction of the arrow shown in FIG. 1, the toner 16 stored in the toner case 11 is conveyed toward the toner carrying roller 14. Then, the toner 16 supplied from the supply roller 12 is rubbed against the toner carrying roller 14 by the toner layer regulating blade 18 to be thinned and has a predetermined polarity, here negative polarity (minus).
The toner layer is charged to a toner layer and is carried on the toner carrying roller 14 as a thin toner layer having a uniform thickness.

At this time, the toner layer regulating blade 18 is
In particular, the shape of the pressure contact portion of the rod-shaped body 18b is uniform in the longitudinal direction and has a smooth surface.
Further, since the pressure contact force is kept uniform by the elastic plate 18a anywhere in the width direction, the thickness of the toner layer carried on the surface of the toner carrying roller 14 is made uniform, and , Its surface condition can be made very smooth, and a predetermined charge amount (charge amount) can be uniformly applied to all toner particles forming the toner layer, and the charge condition can be changed. It can be uniform.

The toner 16 carried as a thin toner layer on the surface of the toner carrying roller 14 has the opening portion of the aperture electrode body 1 as the carrying roller 14 rotates in the direction of arrow B shown in FIG. 6 is carried toward the vicinity of the opening 6 (aperture electrode body 1 and the toner carrying roller 14 in this process), so that the toner on the carrying roller 14 is weakened in its adhesive force. 6), it is possible to control the toner flow with a low control voltage.

That is, when the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 come into contact with each other near the opening 6, the toner particles roll on the carrying roller 14 and the toner particles stand still. It is possible to separate the toner carrier 14 from the toner carrier 14 with a weaker control voltage than that in the current state.

As a result, the toner (charged particles) 16 supplied to the vicinity of the opening 6 of the aperture electrode body 1 in a state in which the adhesive force with the toner carrying roller 14 is sufficiently relaxed is opened in accordance with the image signal. The passage of section 6 is controlled.

For example, when a positive voltage of +30 V is applied from the control voltage applying circuit 8 to the control electrode 4 corresponding to the image portion in accordance with the image signal, the opening 6 of the opening 6 corresponding to the control electrode 4 is applied. In the vicinity, due to the potential difference (electric field) between the control electrode 4 and the toner carrying roller 14, an electric force line from the control electrode 4 toward the toner carrying roller 14 is formed.
As a result, the toner 16 charged in the negative polarity (negative) receives an electrostatic force in the direction of high potential, and is drawn from the toner carrying roller 14 through the opening 6 to the control electrode 4 side. The toner 16 thus extracted is further flown toward the recording medium 20 by an electric field formed between the recording medium 20 and the aperture electrode body 1 by the high voltage of +1 kV applied to the back electrode plate 22. Then, the pixels are deposited on the medium 20 to form dot-shaped pixels.

A negative voltage of -30 V is applied from the control voltage applying circuit 8 to the control electrode 4 corresponding to the non-image area. As a result, an electric field from the control electrode 4 toward the toner carrying roller 14 is not formed between the toner carrying roller 14 and the control electrode 4, and cannot pass through the opening 6. Moreover, a voltage lower than that of the toner carrying roller 14 is applied to the control electrode 4
Since an electric field opposite to the electric field corresponding to the image portion is formed between them, the toner 16
The flight of is suppressed more effectively. Therefore, an image with less fogging is formed.

In such an image forming process,
Since the toner layer carried and formed on the toner carrying roller 14 by the toner layer regulating blade 18 is mechanically and electrically uniform, the mechanical flow under the opening (aperture) is also very large. In addition to being stable, the electrostatic force due to the control voltage can be directly received, and as a result, an extremely high quality image with less density unevenness and fog can be obtained.

On the other hand, the aperture electrode body 1 and the back electrode plate 22
The recording medium 20 conveyed through the gap between the two is fed by one pixel in the direction orthogonal to the row of the openings (apertures) 6 while one row of pixels is formed on the surface thereof by the toner 16. . And by repeating the above process,
A toner image is formed on the entire surface of the recording medium 20. afterwards,
The toner image formed on the recording medium 20 is transferred to the thermal fixing device 26.
It is fixed on the recording medium 20.

In the image forming apparatus of this embodiment, since the insulating toner is used as the toner 16, the insulating property between the toner carrying roller 14 and the control electrode 4 can be ensured, and the opening ( There is no risk of dielectric breakdown of the aperture 6 by mistake.

Further, even when the toner 16 is no longer present on the toner carrying roller 14 due to a defect in the toner supply system, the insulating sheet 2 of the aperture electrode body 1 causes a gap between the control electrode 4 and the toner carrying roller 14. Since the insulating property is ensured, the control electrode 4 and the toner carrying roller 14 are not electrically short-circuited by mistake, and there is no fear of damaging the control drive element or the like.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, in the above embodiment, the rod-shaped body (pressing rod) 18b of the toner layer regulating blade 18 is constituted by a round rod such as stainless spring steel. However, as shown in FIGS. May be an elliptical rod-like body 28b, or as shown in FIGS. 9, 10, 11 and 12, a rod-like body having an appropriate rectangular shape such as a triangular, quadrangular or hexagonal sectional shape. It may be the body 38b.

Further, the rod-shaped bodies 18b, 28b, 38b
The material is not limited to stainless steel, metal materials such as free-cutting steel and aluminum, and synthetic resin materials and the like can be used as long as they satisfy mechanical and electrical properties. is there. Similarly, the material of the elastic plate 18a is not limited to a spring metal material such as stainless spring steel or phosphor bronze, but may be another elastic metal material, or a synthetic resin material having an appropriate elasticity. But it doesn't matter.

Further, in the above embodiment, the aperture electrode body was used as the electric field control means (toner flow control means), but for example, a mesh-shaped electrode as described in JP-A-1-503221. It is also possible to use the body.

[0048]

As is apparent from the above description,
According to the image forming apparatus of the present invention, the toner layer regulating member that regulates the toner layer thickness is a rod-shaped body extending in the direction orthogonal to the toner transport direction, and the rod-shaped body has one end fixed to the rod-shaped body. Since it is composed of the elastic plate that is pressed against the toner carrier, the rod-shaped body can be processed by itself with extremely high precision, and in particular, its surface shape can be finished uniformly and smoothly. Therefore, a thin and uniform toner layer can be formed on the surface of the toner carrier, and excellent image quality without density unevenness and stable image formation are possible.

Also, since the rod-shaped body is made of a round rod made of metal such as stainless steel or aluminum, for example, it can be easily and accurately performed according to the manufacturing method of the wire dot used in the impact type dot printer. It can be processed.

Further, since the elastic plate is made of a spring metal material such as stainless spring steel or phosphor bronze, a metal rod-like body can be easily formed by using a general joining means such as welding or brazing. In addition, it is possible to securely fix the elastic member, and the elastic force can be evenly applied to each part in the longitudinal direction of the rod-shaped body. Therefore, the rod-shaped body can be pressed against the surface of the toner carrier under the same conditions anywhere in the longitudinal direction, and a thin and uniform toner layer can be formed.

Furthermore, since the flow of the toner carried by the toner carrier is directly controlled by the electric field control means, a thin and uniform toner layer is used to form a high-quality image without density unevenness. It can be stably formed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an image forming apparatus embodying the present invention.

FIG. 2 is a partially cutaway perspective view of an aperture electrode body showing an embodiment of the electric field control means of the present invention.

FIG. 3 is a perspective view of a toner layer regulation blade showing a first embodiment of the present invention.

FIG. 4 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller in the first embodiment of the present invention.

FIG. 5 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller according to a second embodiment of the present invention.

FIG. 6 is an enlarged view of an essential part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller in a third embodiment of the present invention.

FIG. 7 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller according to a fourth embodiment of the present invention.

FIG. 8 is an enlarged view of an essential part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller in a fifth embodiment of the present invention.

FIG. 9 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller according to a sixth embodiment of the present invention.

FIG. 10 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller in a seventh embodiment of the present invention.

FIG. 11 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller according to an eighth embodiment of the present invention.

FIG. 12 is an enlarged view of a main part showing a correspondence relationship between a toner layer regulating blade and a toner carrying roller according to a ninth embodiment of the present invention.

FIG. 13 is a schematic configuration diagram showing a conventional image forming apparatus.

FIG. 14 is a perspective view of a toner layer restriction blade showing another conventional example.

FIG. 15 is an enlarged view of a main part showing a corresponding relationship between a toner layer regulating blade and a toner carrying roller in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aperture electrode body (electric field control means) 2 Insulating sheet 4 Control electrode 6 Opening part (aperture) 14 Toner carrying roller (toner carrying body) 16 Toner (charged particles) 18 Toner layer regulating blade 18a Elastic plate 18b Rod-like body (pressure contact) Bar) 20 recording medium 22 back electrode plate (counter electrode) 28b rod-shaped body (pressure welding rod) 38b rod-shaped body (pressure welding rod)

Claims (4)

[Claims] 1. An image forming apparatus comprising: a toner carrier for carrying charged toner; and a toner layer restricting member for restricting a layer thickness of the toner carried by the toner carrier, wherein the toner layer restricting member is provided. An image forming method characterized in that the member is composed of a rod-shaped body extending in a direction orthogonal to the toner transport direction, and an elastic plate having one end fixed to the rod-shaped body and pressing the rod-shaped body toward the toner carrier. apparatus. 2. The rod-shaped body is made of stainless steel, or
The image forming apparatus according to claim 1, wherein the image forming apparatus comprises a round bar made of metal such as aluminum. 3. The image forming apparatus according to claim 2, wherein the elastic plate is made of a spring metal material such as stainless spring steel or phosphor bronze. 4. The image is formed by directly controlling the flow of toner carried by the toner carrier by the electric field control means.
The image forming apparatus according to any one of 1.