JPH08108565A - Image forming device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent wrinkles from occurring in the electrode array 1. An electrode array 1 is arranged between a rear electrode body 2 on which an image recording medium 3 abuts and a toner carrying roller 16 so that a plurality of rows of openings 12 are arranged in parallel with a rotation axis of the toner carrying roller 16. Arranged and four tension rollers 26
a, 26b, 26c and 26d are pressed into contact with the four corners of the surface of the electrode array 1, and these tension rollers are rotated by drive motors 27a, 27b, 27c and 27d to sandwich the row of openings 12 on both sides. A tension force is applied to the electrode array 1 to prevent wrinkles from occurring in the electrode array 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an image forming apparatus which can be used in a copying machine, a facsimile machine, a printer, etc., and more specifically, an image forming apparatus for forming an image by flying charged toner by an electric field. It is about.

[0002]

2. Description of the Related Art Heretofore, as an image forming apparatus of this type, the applicant of the present invention has previously disclosed that a thin film-like electric insulating sheet is provided with a plurality of openings in a line in JP-A-6-155798. A control electrode is provided in each of the electrode arrays for each opening, and an image recording such as a sheet is formed on the opposite side of the toner carrying roller as a toner supplying means in the toner case containing the toner with the electrode array sandwiched therebetween. An image forming apparatus for forming an image on the image recording medium by controlling the passage of the charged toner through an opening by a control voltage applied to each control electrode by positioning the medium, A sheet-holding roller having a rotation axis orthogonal to the moving direction of the image recording medium, and a toner supply roller for slidingly contacting the outer peripheral surface of the toner-holding roller with the toner; Image recording medium a plurality of portions of the outer peripheral portion of the electrode array with the openings in a row in a direction perpendicular to the direction of movement, and proposed that fixed to the upper surface of directly said toner case of.

In this case, the film-shaped electrode array is tensioned so that the vicinity of the lower surface of each opening in the electrode array comes into contact with the outer peripheral surface of the toner carrying roller with a substantially uniform contact pressure. It was fixed to the toner case via.

[0004]

However, the electrode array itself or the adhesive may be partially wrinkled due to aging, or the electrode array may expand when energy is applied to the image forming apparatus. Due to
The tension on the electrode array fixed to the toner case is relaxed, and the contact pressure on the outer peripheral surface of the toner carrying roller is reduced as a whole, or the contact pressure is partially changed,
There is a problem in that the amount of toner passing through each opening becomes non-uniform and uneven density of the image and distortion of the image occur, which deteriorates the printing quality.

Further, the plurality of locking portions on the wide surface of the thin film-shaped electrode array are locked at the ends of the plurality of tension springs to apply a tension force to the electrode array on the substantially wide surface of the film. When applied, each locking part in the thin film of the electrode array has an edge of this tension spring due to the difference in magnitude between the component force in the tension direction by each tension spring and the component force in the direction intersecting with it. Since wrinkles are formed on the electrode array in the locking portion near the portion, and the contact pressure of the electrode array on the outer peripheral surface of the toner carrying roller becomes uneven in each opening,
The above problems could not be resolved.

The present invention has been made to solve these technical problems, and it is an object of the present invention to provide an image forming apparatus capable of obtaining stable print quality without causing wrinkles in the electrode array. It is intended.

[0007]

In order to achieve the above object, the image forming apparatus of the invention according to claim 1 is a film-shaped electrode in which a plurality of openings are formed and each opening has a control electrode. An array, a toner supply means for supplying toner to the openings of the electrode array, an image recording medium arranged on the opposite side of the electrode array from the toner supply means, and each control electrode of the electrode array are independent. An image composed of a control circuit element that controls the toner to selectively fly the toner from the toner supply means through the opening onto the image recording medium, and a pulling means that applies a tension force to the electrode array. In the forming device, the electrode array includes
Openings are formed in rows in a direction intersecting with the moving direction of the image recording medium, and the pulling means is configured to press the surface of the electrode array toward the surface side of the toner supply means. is there.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a plurality of the pulling means are arranged with the row of the openings sandwiched therebetween, and on both sides of the openings. ,
The surface of the electrode array is configured to be pressed toward the surface of the toner supply unit. According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a pair of pulling means is arranged so as to sandwich the row of the openings, and a direction intersecting the row of the openings in the electrode array. In order to apply a tension force to the two, both of the pulling means are configured to apply a rotational frictional force to the surface of the electrode array.

[0009]

Next, an embodiment of the present invention will be described. FIG. 1 shows an outline of an image forming apparatus of the present invention, which is about 1 mm from the surface of an electrode array 1 as toner flow control means.
The metal-roller-shaped back electrode body 2 rotating in the direction of arrow A is supported by a frame (not shown) with a space of.

An image recording medium 3 such as a printing paper, which is inserted in a gap between the electrode array 1 and the back electrode body 2, can be conveyed in the direction of arrow B by a paper feeding device 4 composed of a roller pair. On the downstream side in the transport direction of the image recording medium 3,
A fixing device 5 including a heating roller 6 and a pressing roller 7 for fixing an image is arranged. Next, the respective components will be described in detail. A toner supply device 8 as a toner supply unit includes a toner case 9 that also serves as a housing.
The toner 18 contained in the toner case 9, the supply roller 15, the conductive toner carrying roller 16 made of a metal cylinder such as copper or aluminum, and the like. A toner carrying roller 16 and a supply roller 15 having a rotating shaft in a direction orthogonal to the direction in which the image recording medium 3 is conveyed.
Have substantially the same length and are rotated in the directions of arrows D and C in FIG. 1 by a rotation driving device (not shown).

12 rows of openings of the electrode array 1 to be described later are
It is arranged on the back surface of the insulating sheet 11 along the axis of the toner carrying roller 16 so that the opening 12 contacts a part of the outer peripheral surface of the toner carrying roller 16. The base end of a regulating blade 19 for regulating the toner layer thickness, which is in pressure contact with the peripheral surface on the upstream side of the rotation of the toner carrying roller 16, is fixed to the toner case 9, and the toner 18 supplied by the supply roller 15 is supplied.
Is slidably contacted with the outer peripheral surface of the toner carrying roller 16 by the regulation blade 19 to regulate the layer thickness of the toner 18 to a predetermined uniform thickness and to charge the toner 18.

As shown in FIGS. 1 to 5, the electrode array 1 has a plurality of openings 12 each having a diameter of about 100 μm on an insulating sheet 11 made of polyimide as an electrically insulating base material having a thickness of about 25 μm. The control electrodes 13 are formed in one row in the direction orthogonal to the moving direction of the medium 3, and are divided into the openings 12 on the side facing the image recording medium 3.
To form.

If the insulating sheet 11 is made too thin,
A polyimide resin having a thickness of 25 μm is suitable because it becomes difficult to form the control electrode 13 and handle the electrode array 1 itself. As shown in FIG. 3, for each opening 12 such as a round hole formed through the insulating sheet 11, an annular electrode portion is provided above the insulating sheet 11 along the circumference of the opening 12. A control electrode 13 composed of 13a and a lead portion 13b for connecting each electrode portion 13a to the control voltage applying circuit 21 is formed of a metal such as copper or gold having a thickness of about 1 μm.

In the embodiment shown in FIGS. 2 and 3, the lead portion 13b of the control electrode with respect to the openings 12 arranged in a line extends along the moving direction of the image recording medium 3, and the lead portions 13b shown in FIGS. As shown, the frame 25 fixed to the upper flange portion of the toner case 9 is formed with an opening hole 25a facing the upper surface of the toner carrying roller 16 and extends in the front-back direction along the axis of the toner carrying roller 16. A pair of ridges 2
3 and 23 are projected upward. The sheet 11 on the back surface side of the electrode array 1 arranged so as to cover the pair of protrusions 23, 23, the opening hole 25a, and the toner carrying roller 16.
Reinforcing plates 24 made of a rubber plate, a resin plate, or the like arranged so as to extend parallel to the axis of the toner carrying roller 16 on both front and back surfaces of the front and rear portions of the outer peripheral edge of the image recording medium 3 in the moving direction. , 24 are stretched with an adhesive, rivets, eyelets or the like, and both reinforcing plates 24, 24 are fixed to the frame body 25.

Further, in the first embodiment, the tension rollers 26a, 26b, 26 as four tension means are provided between the ridge 23 on the frame 25 and the reinforcing plate 24.
c and 26d are arranged so as to come into contact with the front and rear portions on the front surface side of the electrode array 1, and the tension rollers 26
a, 26b, 26c, 26d are respectively driven by a drive motor 27
A, 27b, 27c, and 27d are configured to rotate in the arrow E direction in FIG. 2 and in the opposite arrow E'direction.

As a result, the back surface of the sheet 11 in the electrode array 1 stretched at the pair of protrusions 23, 23 comes into contact with the upper surface of the toner carrying roller 16 and the four tension rollers that rotate. 26a, 26b,
26c and 26d are configured to apply tension to the seat 11 in a direction (Y direction shown in FIG. 2) orthogonal to the row of the openings 12.

In this state, the row of the openings 12 is kept pushed upward by the outer peripheral upper surface of the toner carrying roller 16, so in other words, the row of the openings 12 is arranged with respect to the toner carrying roller 16. Seat 11 centered on
Is bent at substantially the same angle on the upstream side and the downstream side in the moving direction of the image recording medium 3 so that the opening 12 in one row comes into uniform pressure contact with the outer peripheral surface of the toner carrying roller 16, and the outer peripheral surface of the toner carrying roller 16 is It has a component of tension force in the direction of increasing the contact area with.

A DC power source 20 is connected between the back electrode body 2 and the toner carrying roller 16, and the back electrode body 2
A high voltage of about +1 kV is applied to the toner carrying roller 16 and the control voltage application circuit 21.
Are connected to each other, and a voltage of 0 V or +50 V is applied to the control electrode 13 based on an image forming signal from a data control circuit (not shown).

The toner 18 is an electrically insulating toner having an electrically insulating property, and is supplied to the surface of the toner carrying roller 16 by the supply roller 15. Conductive toner carrying roller 1
Including the surface 6 and the toner 18 attached thereto, the potential becomes the same as a whole. Next, the recording operation (printing operation) of the image forming apparatus thus configured will be described.

First, the toner carrying roller 16 and the toner supply roller 15 having substantially the same length as the toner carrying roller 16 rotate in the directions of arrows D and C shown in FIG. The insulating toner 18 sent from the supply roller 15 is rubbed against the surface of the toner carrying roller 16 and is charged to a large negative value.

Next, the blade 1 for regulating the toner layer thickness
At 9, the layer thickness of the toner 18 is thinned to a predetermined value, and the toner 18 carried on the surface of the toner carrying roller 16 is conveyed toward the electrode array 1 by the rotation of the toner carrying roller 16. The surface of the toner carrying roller 16 is rubbed against the insulating sheet 11 on the lower surface of the electrode array 1. At this time, the four corner portions of the electrode array 1 have tension rollers 26a, 26 which rotate on both sides of the row of openings 12 with the row of openings 12 interposed therebetween.
As a result of being rubbed by b, 26c and 26d, a tension force is simultaneously applied in the Y direction and the Y'direction.

That is, the tension rollers 26a, 26b,
The tensile force generated by the frictional resistance of rubbing the surfaces of the film-shaped electrode array 1 in the opposite directions at 26c and 26d is applied to the wide surface of the electrode array 1 via the pair of ridges 23 and 23. Of the toner carrying roller 1 without causing wrinkles in the electrode array 1 by being substantially evenly dispersed.
A uniform and stable contact can be obtained between the front surface 6 and the back surface of the electrode array 1.

If there is an image, the control voltage application circuit 21 is driven based on the image signal from the data control circuit, and +50 is applied to the control electrode 13 corresponding to the image portion.
A voltage of V is applied. As a result, in the vicinity of the opening 12 corresponding to the image portion, due to the potential difference between the control electrode 13 and the conductive toner carrying roller 16, an electric force line from the ring-shaped control electrode portion 13a toward the toner carrying roller 16 is generated. It is formed. The strength of the line of electric force at this time is proportional to the potential difference and inversely proportional to the distance between the control electrode 13 and the surface of the toner carrying roller 16.

Then, the negatively charged toner 18
Is subjected to an electrostatic force in the direction of higher potential by the line of electric force from the control electrode 13 toward the toner carrying roller 16, and is drawn out so as to pass through the opening 12. The toner 18 thus extracted is further subjected to the voltage (+1 kV) applied to the back electrode body 2 so that the image recording medium 3
The electric field formed between the electrode array 1 and the electrode array 1 causes the toner 18 to fly toward the image recording medium 3, and the toner 18 is deposited on the surface of the image recording medium 3 to form a visible pixel.

In this case, as described above, the electrode array 1 is not wrinkled, and the contact between the outer peripheral surface of the toner carrying roller 16 and the row of the openings 12 is uniform and stable.
It is possible to obtain an image without uneven toner density or image distortion. In the non-image operation, the control voltage application circuit 21 is driven according to the signal from the data control circuit to apply a voltage of 0 V to the control electrode 13 for the non-image portion. As a result, the toner carrying roller 16 and the control electrode 13
Since no electric field is formed between the toner and the toner, the toners 18 on the toner carrying roller 16 are not subjected to the electrostatic force, and the toners 18 do not pass through the opening 12.

Further, the opening 1 is formed on the surface of the image recording medium 3.
While one row of toner 18 is formed by the two rows, the image recording medium 3 is conveyed by one pixel in the direction perpendicular to the row of the openings 12 (direction of arrow B in FIG. 1). By repeating such an operation, a predetermined image is formed by the toner 18 on the surface of the image recording medium 3. After that, the toner image is heated and fixed on the image recording medium 3 at the position of the fixing device 5.

In the image forming apparatus constructed as described above, when the insulating toner 18 is used, the conductive toner carrying roller 16 and the control electrode 1 in the electrode array 1 are used.
The electrical insulation between 3 and 3 is maintained. In the second embodiment shown in FIG. 6, the pair of ridges 23, 23 shown in FIG. 2 and the like are omitted, and the four corner portions of the electrode array 1 are tension rollers 26a, 26b, 2 as four pulling means.
By pressing at 6c and 26d, the back surface of the sheet 11 is pressed against the outer peripheral surface of the toner carrying roller 16, and the four tension rollers rotate in the arrow E and E'directions, respectively. The pulling force is generated by the frictional resistance of rubbing the surfaces of the electrode array 1 in the opposite directions, and substantially the same as in the first embodiment, the electrode array 1 is free from wrinkles and each opening 12 has toner. Since the outer peripheral surface of the carrier roller 16 is uniformly contacted and is stable, an image can be obtained in which uneven toner concentration and image distortion do not occur.

In the non-image operation, the control voltage application circuit 21 is driven according to the signal from the data control circuit so that a negative voltage such as -10V is applied to the control electrode 13 for the non-image portion. May be. In this case,
An electric field opposite to the electric field with respect to the image forming portion is formed between the toner carrying roller 16 and the control electrode 13, so that the flying of the toner 18 on the toner carrying roller 16 can be further suppressed, and fogging is reduced. An image can be formed.

According to the above process, the control electric field in the electrode array 1 is formed between the control electrode 13 and the surface of the toner carrying roller 16 as one electrode facing the opening 12. The electric field for control can be directly applied to the toner 18 conveyed by the toner carrying roller 16 to the vicinity of the opening 12, and the toner control efficiency is excellent.

Since the toner carrying roller 16 which is one of the electrodes and the electrode array 1 having the control electrode 13 are located very close to each other with the toner 18 being conveyed therebetween, the applied voltage for control is applied. Even if it is lowered, the electric field strength can be increased and the flying force of the toner 18 can be increased. Therefore, an integrated circuit element for low voltage can be used as a control voltage application circuit for driving the control electrode 13, The manufacturing cost of the forming apparatus becomes low.

If the electrically insulating sheet 11 in the electrode array 1 is brought into contact with the outer peripheral surface of the toner carrying roller 16 as one of the electrodes, even if the toner 18 is not carried on the toner carrying roller 16, it is electrically charged. There is no short circuit. The tension roller as the pulling means is formed longitudinally along the row of the openings 12 as shown by the chain double-dashed line in FIG. 4, instead of the four corner portions of the electrode array 1 in plan view. You may make it equip each with a drive motor. Furthermore, in each of the above embodiments,
If the drive motor that rotates the tension roller is configured to operate only during the printing operation, the tensile force of friction with the electrode array 1 due to the rotation of each tension roller is not always applied to the electrode array 1, so that the long-term It is possible to prevent the disadvantage that the electrode array 1 unnecessarily extends during use.

An integrated circuit chip (IC) for applying the control voltage may be mounted on both sides or one side of the electrode array 1 with the row of openings 12 interposed therebetween. Although the tension rollers are arranged on both sides of the opening in this embodiment, they may be arranged on only one side of the opening.

[0033]

As described above, claim 1
The image forming apparatus according to the invention described in 1), a plurality of openings are formed, each opening has a film-like electrode array each having a control electrode, a toner supply unit for supplying toner to the openings of the electrode array, The image recording medium disposed on the opposite side of the electrode array from the toner supply unit and each control electrode of the electrode array are independently controlled to transfer the toner from the toner supply unit to the image through the opening. In an image forming apparatus comprising a control circuit element for selectively flying on a recording medium and a pulling means for applying a tension force to the electrode array, the electrode array intersects the moving direction of the image recording medium. The pulling means is configured to press the surface of the electrode array toward the surface side of the toner supply means.

As described above, according to the present invention, the tension means presses the film-shaped electrode array 1 in the thickness direction thereof, so that the tension force is applied in the direction along the wide surface of the electrode array. become. Moreover, since the pulling means presses the electrode array toward the surface side of the toner supply means, the extension of the electrode array due to this tension force is substantially evenly distributed over the wide surface of the electrode array to form the electrode array. There is no occurrence of fire.

Therefore, there is an effect that a stable image formation can be executed without causing unevenness in toner density or image distortion during an image forming operation. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, a plurality of the pulling means are arranged so as to sandwich the row of the openings, and the pulling means are provided on both sides of the openings of the electrode array. The surface is pressed toward the surface of the toner supply unit.

Therefore, the extension of the electrode array due to the tension force is more evenly distributed to the wide surface of the electrode array on both sides of the opening, and wrinkles do not occur in the electrode array. Further, since the surface of the toner carrying roller and the row of the openings of the electrode array can be brought into uniform and stable contact, there is no unevenness in the toner density during the image forming operation and no distortion in the image. Thus, the effect that stable image formation can be executed is achieved.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the image forming apparatus described above, a pair of pulling means is arranged so as to sandwich the row of openings, and both pulling means are provided with electrodes in order to apply a tension force to the electrode array in a direction intersecting the row of openings. It is configured to apply a rotational frictional force to the surface of the array. Therefore, unlike the conventional tension spring, a tensile force that concentrates on one place of the electrode array is not generated, and therefore, wrinkles are not generated in the electrode array as in the invention according to claim 1, and Since a uniform and stable contact can be obtained between the surface of the toner carrying roller and the row of openings of the electrode array, there is no unevenness in the toner density during image forming operation, and there is no distortion in the image, which is stable. There is an effect that image formation can be executed.

In addition, since the film-shaped electrode array is tensioned in the thickness direction by the pulling means, it does not loosen even if the electrode array expands due to changes over time, and does not loosen. The opening of the electrode array can be always brought into close contact with the outer peripheral surface of the carrier roller, and stable printing quality can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of an image forming apparatus.

FIG. 2 is a perspective view showing a mounting state of an electrode array on a toner case in the first embodiment.

FIG. 3 is a perspective view of a main part of an electrode array.

FIG. 4 is a plan view showing an arrangement state of an electrode array and a pulling unit.

5 is a cross-sectional view taken along the line VV of FIG.

FIG. 6 is a sectional view of a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Electrode array 2 Back electrode body 3 Image recording medium 8 Toner supply device 9 Toner case 11 Insulating sheet 12 Opening 13 Control electrode 16 Toner carrier roller 21 Control voltage applying circuit 23, 23 Protrusion 24 Reinforcing plate 25 Frame 26a, 26b , 26c, 26d Tension rollers 27a, 27b, 27c, 27d as pulling means Driving motors

Claims (3)

[Claims] 1. A film-shaped electrode array having a plurality of openings, each opening having a control electrode, a toner supply unit for supplying toner to the openings of the electrode array, and an electrode array for the electrode array. The image recording medium arranged on the opposite side of the toner supply means and each control electrode of the electrode array independently to select the toner from the toner supply means on the image recording medium through the opening. In an image forming apparatus including a control circuit element for causing the electrode array to fly and a pulling unit for applying a tension force to the electrode array, the electrode array has a row-like array in a direction intersecting the moving direction of the image recording medium. The image forming apparatus is characterized in that an opening is formed in the opening, and the pulling unit presses the surface of the electrode array toward the surface of the toner supply unit. 2. A plurality of the pulling means are arranged so as to sandwich the row of the openings, and the pulling means is configured to press the surface of the electrode array toward the surface of the toner supplying means on both sides of the openings. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed. 3. A pair of pulling means are arranged so as to sandwich the row of openings, and both pulling means of the electrode array are arranged so as to apply a tension force to the electrode array in a direction intersecting the row of openings. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to apply a rotational frictional force to the surface.