JPH10200668A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide images without fogging and nonuniformity by setting the Young's modulus of a charge body control means for controlling the passing of a charge body and a charge body carrying means for carrying and supplying the charge body to a surface to be less than the Young's modulus of the charge body. SOLUTION: A toner 16 is carried on the peripheral surface of a toner- carrying roller 14 and charged to negative polarity by a blade 18 and a pressurized contact state is released by a control electrode 4 from an aperture 6. At this time, by making the Young's modulus of the toner 16 larger than the Young's moduli of a printing head 1 and the toner carrying roller 14, storage elastic energy by elastic compression distortion is made small, jumping out from the aperture 6 is suppressed at the time of being released from the compressed state, and generation of the fogging on a recording medium is eliminated. Also, since the mechanical strength of the toner 16 is higher than those of the printing head 1 and the toner carrying roller 14, it is not destroyed at a pressurized contact part, the fixation and aggregation of the toner 16 are prevented, and the generation of striped nonuniformity is suppressed.

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 used for a copying machine, a printer, a facsimile, a plotter, and the like.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus which obtains an image on a recording medium by controlling the passage of toner by applying an image signal to a charged body flow control means having a toner flow path is disclosed in It has been proposed in Japanese Patent Application Laid-Open No. 6-255163 according to the applicant. Further, an apparatus using an opening (hereinafter, referred to as an aperture) as the toner flow path has been proposed in, for example, Japanese Patent Application Laid-Open No. 6-155798.

In the image forming apparatus, charged toner flow control means (hereinafter referred to as a print head) is formed by arranging toner flow paths on an insulating sheet and forming control electrodes corresponding to the toner flow paths. ), And a toner carrying roller for carrying the toner on the surface. Further, the image forming apparatus is configured such that one surface of the print head is brought into contact with the peripheral surface of the toner carrying roller in the vicinity of the toner channel arrangement. The image forming apparatus controls the passage of the charged toner, which is a charged body, through the toner channel by applying a voltage (hereinafter, referred to as a control voltage) according to image data to the control electrode. Forming a toner image on a recording medium disposed on the opposite side of the toner carrying roller with the print head interposed therebetween.

In this image forming apparatus, the toner on the toner carrying roller and the print head are in contact with each other via the toner near the toner flow path. Therefore,
By rubbing the so-called blocking toner which adheres to the vicinity of the toner flow path and tries to hinder the toner supply with the toner supplied later, the toner supply to the toner flow path is not hindered.

In this image forming apparatus, a control voltage corresponding to an image signal is applied to a control electrode to form an electrostatic field (hereinafter, referred to as a control field) in and near the toner flow path. By applying an electrostatic force to the charged toner by the action of the control electric field, the passage of the toner through the toner flow path is controlled.

At this time, the toner supplied to the toner flow path while being carried on the toner carrying roller is applied to the surface of the toner carrying roller by a physical image such as a mirror image force due to the charge of the toner itself and a van der Waals force. Are adhered by a strong adhesive force, which is a resultant force with a natural force. Therefore,
In order to apply an electrostatic force to the toner that overcomes the strong adhesive force to separate the toner from the surface of the toner carrying roller, a considerably high control voltage is required.

However, in the image forming apparatus having the above configuration,
When the toner carried on the toner carrying roller surface comes into sliding contact with the print head in the vicinity of the toner flow path, a mechanical force is given to the toner. Is released. Therefore, the passage of the toner through the toner flow path can be controlled with a small control voltage.

Further, the configuration in which the print head and the toner on the toner carrying roller are in contact with each other means that the control electrode on the print head and the surface of the toner carrying roller carrying the toner are extremely close to each other. That is, since a strong control electric field can be obtained even with a small control voltage, an image can be formed with high contrast.

[0009]

However, in the conventional image forming apparatus as described above, the toner on the toner carrying roller is conveyed to the toner flow path while receiving pressure from the print head and the toner carrying roller. So
When the toner reaches just below the toner flow path and is released from the pressure, the toner jumps up from above the supporting roller with elastic energy stored in the toner, and passes through the toner flow path regardless of the control of the control electric field. There was a problem of fogging of the image.

[0010] Further, the toner is destroyed by the pressure and gradually adheres to the surface of the print head or the toner carrying roller, and there is a problem that as the number of prints increases, stripe-shaped unevenness occurs in the formed image.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to provide an image forming apparatus capable of obtaining an image without fogging or unevenness.

[0012]

In order to solve the above-mentioned problems, an image forming apparatus according to a first aspect of the present invention comprises:
A charged material flow control means including a charged material flow path through which the charged material passes, and a control electrode for controlling passage of the charged material in the charged material flow path; and supplying the charged material to the charged material flow control means. A charge carrying means for carrying a charged body on the surface thereof, by bringing the charged body carrying means into contact with the charged body flow control means via the charged body, thereby providing the charged body flow path. By supplying the charged body and controlling the passage of the supplied charged body by the control electrode, the recording medium is disposed on the opposite side of the charged body carrying means with the charged body flow control means interposed therebetween. The image forming apparatus is characterized in that the charged material flow control means and the charged material carrying means have a Young's modulus less than or equal to the charged material's Young's modulus.

According to this configuration, the charged body is supplied to the charged body flow path while receiving pressure between the charged body flow control means and the charged body holding means, and the charged body is provided immediately below the charged body flow path. When the charged body is released from the pressure, the charged body does not accidentally pass through the charged body flow path due to the recovery of the elastic strain.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 according to the present embodiment.

A toner supply device 10 is disposed below the image forming apparatus, and an upper portion of the toner supply device 10
A print head 1 is provided as charged body flow control means, which is a means for controlling toner flow. A back electrode roller 22 is rotatably disposed above the print head 1 with a gap of about 1 mm. In the gap between the print head 1 and the back electrode roller 22, the recording medium 20 is moved by the rotation of the back electrode roller 22 in the direction of arrow D shown in FIG. Are transported in the direction of arrow C shown in FIG.
Are arranged. The heat fixing device 26 can use a heat fixing method or a pressure fixing method.

Next, the details of each component will be described.

As shown in FIG. 1, the toner supply device 10 includes a toner case 11 which also serves as a housing of the entire device.
Inside, preferably an insulating toner 16 as a charged body
And a toner carrying roller 14 serving as a charged body carrying means, which is a cylindrical member for carrying the toner 16 on its surface and transporting it toward the print head 1.
Are provided so as to be rotatable in the direction of arrow B shown in FIG.

The toner carrying roller 14 is formed by forming a coating layer of a synthetic resin or a synthetic rubber around a cylindrical surface of a metal roller member, so that the metal roller member is electrically grounded. , Provided in the toner case 11.

A cylindrical supply roller 12 for supplying the toner 16 contained in the toner case 11 to the toner carrying roller 14 is provided obliquely below the toner carrying roller 14 in FIG. Are provided rotatably in the direction of arrow A shown in FIG. The supply roller 12 and the toner carrying roller 14 are disposed in parallel with each other so as to be in pressure contact with each other via the toner 16.

Above the supply roller 12 in the toner case 11, the amount of the toner 16 carried on the roller surface of the toner carrying roller 14 is uniformly adjusted on the roller surface, and the toner A blade 18 for uniformly charging the roller 16 is disposed so as to press the roller surface of the toner carrying roller 14 against the roller.

As shown in FIG.
For example, an aperture 6 as a charged channel having a diameter of about 60 μm is arranged in a line in the longitudinal direction of the print head 1 on a base film 2 which is a synthetic resin film having an insulating property such as a polyester film having a thickness of about 25 μm. The control electrodes 4 made of a conductive metal pattern such as copper or gold having a thickness of about 8 μm are formed around the apertures 6 so as to surround the edges of the apertures 6. You.

Here, since the print head 1 is attached to the toner case 11 while applying tension,
The vicinity of the arrangement of the apertures 6 of the print head 1 and the roller peripheral surface of the toner carrying roller 14 are configured to be in pressure contact with the toner 16 therebetween.

The control electrodes 4 are respectively connected to driving elements 8 such as ICs. The drive element 8 sends, for example, 0 to the control electrode 4 based on an image signal sent from an image signal receiving unit (not shown) provided in the image forming apparatus.
OFF voltage of V or -30V, or O of + 30V
It is configured to apply an N voltage. Note that the image signal receiving means is connected to an external device such as a computer, an image reading device, or an image communication device (not shown).

The back electrode roller 22 is disposed directly above and parallel to the arrangement of the apertures 6 in the print head 1, and a voltage of +1 kV is applied to the back electrode roller 22 by a DC power supply (not shown). It is configured to be.

In the image forming apparatus having the above configuration, the toner 16, the base film 2, and the toner carrying roller 14
Are composed mainly of a polyester resin. By selecting the type of additives and monomers as raw materials, for example, the Young's modulus of the toner 16 is 500 kgf / mm ^{2 at} room temperature, 2 Young's modulus 450 kgf / mm ^2, it is possible to adjust the Young's modulus of the toner carrying roller 14 so as to be 420kgf / mm ^2.

Next, the operation of the image forming apparatus configured as described above will be described with reference to FIG.

First, when the supply roller 12 rotates in the direction of arrow A in FIG. 1, the toner 16 contained in the toner case 11 is conveyed toward the toner carrying roller 14. The transported toner 16 is carried on the roller peripheral surface of the toner carrying roller 14 by sliding between the toner carrying roller 14 and the supply roller 12, and the blade 18
As a result, it is formed into a thin and uniform layer
While being rubbed by the blade 18, it is charged to a predetermined polarity, here a negative polarity.

As described above, the toner 16 thinned on the roller peripheral surface of the toner carrying roller 14 by the blade 18 is printed on the toner carrying roller 14 with the rotation of the toner carrying roller 14 in the direction of arrow B. It is conveyed to the pressure contact portion with the head 1.

Since the toner 16 rolls in the pressure contact portion, the toner 16 is supplied to the print head 1 immediately below the aperture 6 in a state where the adhesive force with the toner carrying roller 14 is reduced.

Here, the toner 16 is released from the pressed state. However, as described above, the toner 16 has a higher Young's modulus and a smaller storage elastic energy due to elastic compressive strain than the print head 1 and the toner carrying roller 14. When released from the pressure contact state, it does not accidentally jump out of the aperture 6. Further, according to the above configuration, the toner 16
Since the mechanical strength of the toner is higher than that of the print head 1 and the toner carrying roller 14, the toner is not broken at the press contact portion, and the fixation and aggregation of the toner 16 at this portion can be prevented.

When a control voltage of +30 V, which is an ON voltage, is applied to the control electrode 4 from the drive element 8 in response to the image signal, the control electrode 4 is placed near the aperture 6 corresponding to the control electrode 4. An electric field is generated due to a potential difference between the toner carrier roller 14 and the toner carrier roller 14, and the negatively charged toner 16 receives an electrostatic force in a direction of higher potential, passes through the aperture 6 from the toner carrier roller 14, and is drawn out to the control electrode 4 side. .
The extracted toner 16 further flies toward the recording medium 20 by an electric field formed between the recording medium 20 and the aperture electrode body 1 by a high voltage of +1 kV applied to the back electrode roller 22. Then, they are deposited on the recording medium 20 to form dot-shaped pixels.

Further, the driving element 8 responds to an image signal by
When a control voltage of −30 V or 0 V, which is an OFF voltage, is applied to the control electrode 4, a negatively charged toner 16 is controlled between the control electrode 4 and the toner carrying roller 14 by the toner carrying roller 14. Since an electric field which receives an electrostatic force toward the electrode 4 is not formed, the electric field does not pass through the aperture 6.

When -30 V is used as the OFF voltage, the control electrode 4 has a lower potential than the electrically grounded toner carrying roller 14, and the negatively charged toner 16
An electric field is formed from the control electrode 4 toward the toner carrying roller 14 due to electrostatic force.
Does not accidentally pass through the aperture 6. Therefore, a good image with little fog is formed.

The recording medium 20 conveyed through the gap between the print head 1 and the back electrode roller 22 is orthogonal to the arrangement of the apertures 6 during the recording of one row of the apertures 6 by the toner 16. In one direction, and by repeating this process, the recording medium 2
Thus, a toner image is formed over the entire area of 0. After that, the toner image formed on the recording medium 20 is fixed on the recording medium 20 by the heat fixing device 26.

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

For example, as the material of the toner 16, the print head 1, and the toner carrying roller 14, polyester resins having different Young's moduli are used. However, the present invention is not limited thereto. By doing so, the same effect as above can be obtained. For example, when the toner 16 is a polyester resin, the material of the print head 1 and the toner carrying roller 14 is as follows.
A polyolefin-based synthetic resin such as polyethylene having a smaller Young's modulus than the polyester resin can be used.

Further, if the Young's modulus of the toner 16, the print head 1, and the toner carrying roller 14 are made the same, the elastic strain of the pressed portion is equally distributed, so that the effect of preventing the toner 16 from erroneously flying is the highest. Become.

Further, the print head 1 has an aperture 6
May be used only in the vicinity of the arrangement of the above materials.

[0040]

As is apparent from the above description, according to the image forming apparatus of the present invention, the charged body is charged by the stored elastic energy of the charged body at the contact portion between the charged body flow control means and the charged body carrying means. This solves the problem of erroneously passing through the charged material flow path and causing fogging on the recording medium. Further, since the charged body is not destroyed by the pressure received at the contact portion, the charged body does not adhere to the charged body flow control means or the charged body holding means, and the formed image becomes uneven as the number of prints increases. Is resolved. Therefore, it is possible to provide an image forming apparatus capable of obtaining an image without fog or unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a print head mounted on the image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 print head 4 control electrode 6 aperture 8 driving element 14 toner carrying roller 16 toner

Claims (1)

[Claims] 1. A charged body flow control means comprising a charged body flow path through which a charged body passes, a control electrode for controlling passage of the charged body in the charged body flow path, and a charged body flow control means. In order to supply a charged body, the surface of the charged body carrying means for carrying a charged body, the charged body carrying means, by contacting the charged body flow control means via the charged body, the By supplying the charged body to the charged body flow path and controlling the passage of the supplied charged body by the control electrode, the charged body is disposed on the opposite side of the charged body carrying means with respect to the charged body flow control means. An image forming apparatus for forming an image on a recording medium according to claim 1, wherein a Young's modulus of said charged body flow control means and said charged body carrying means is set to be equal to or less than a Young's modulus of said charged body.