JPH0538843A - Electrostatic recording device - Google Patents

Abstract

PURPOSE:To stably form a recording image of high quality free from scumming by preventing scattering of developing agent in a developing agent transfer passage upstream of a recording section. CONSTITUTION:The forward end of a recording electrode sheet 17, as a recording electrode EL, is positioned at a location where the outer periphery of a development sleeve 15 and the circumferential surface of a cylinder electrode 5 are closely opposed to each other to form a recording section W. The arrangement of the sheet 17 is such that a large number of recording electrode wires 17a are formed in patterns on a base film l7b and a protection coat 17c, wherein an insulating coat layer 17c1 and a conductive coat layer 17c2 are layered, is applied onto said wires. And the layer 17c2 in contact with developing agent (d) is connected to earth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type electrostatic recording apparatus which forms an electrostatically recorded image without bringing a recording head and a recording medium into contact with each other.

[0002]

2. Description of the Related Art Conventionally, as an electrostatic recording system in which plain paper can be used and a minute gap between the image medium and the tip of the recording electrode can be accurately secured, toner is formed on a drum-shaped intermediate recording medium. A method of forming an image and transferring the toner image onto a sheet is used. In the case of this method, the size of the device tends to increase because an intermediate recording medium is used. Therefore, a method is adopted in which a process of simultaneously performing recording and development is adopted to avoid an increase in size of the apparatus. In this method, the recording electrode is placed in a width direction (main scanning direction) at a position facing a counter electrode that also serves as an intermediate recording medium in the developer transport path.
Are arranged in parallel with each other, and the toner conveyed image is formed by selectively transferring the developer conveyed according to the record information at the electrode facing portion from the recording electrode.

Before reaching the electrode facing portion, the developer is liable to be frictional between the developer particles such as toner and carrier, or the surface of the developer carrying member forming the developer transport path or the layer thickness regulating member. It is charged with polarity and electric charge. However, depending on the material of the developer transport path, there are problems that the charge amount is insufficient or that the polarity is opposite to the desired polarity. When the developer is charged in the opposite polarity or the charge amount is insufficient, the background stain is likely to occur.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is capable of triboelectrifying a developer with a desired polarity in a necessary and sufficient manner, and is of high quality without scumming. It is an object of the present invention to provide an electrostatic recording device capable of stably forming various recorded images over a long period of time.

[0005]

SUMMARY OF THE INVENTION There are two main points of the present invention, one of which is, in order to achieve the above-mentioned object, a developer conveying means for conveying a developer along a predetermined developer conveying path, and A two-component developer containing a toner and a carrier is used as the developer, which has a recording electrode and a counter electrode arranged in parallel on the developer transport path with a space therebetween, and a counter electrode facing the recording electrode. Voltage is applied to the electrodes according to the recorded information,
In an electrostatic recording device that selectively transfers the developer conveyed to a recording unit where the recording electrode and the counter electrode face each other to the counter electrode side, at least the developing unit on the upstream side of the developer conveying direction of the recording unit. The point is that the surface in contact with the agent is made of a conductive material and is grounded.

Another aspect of the present invention is, in order to achieve the above-mentioned object, a developer transport means for transporting a developer along a predetermined developer transport path, and an interval is maintained on the developer transport path. A two-component developer including a toner and a carrier is used as the developer, and a voltage is applied to each of the recording electrodes according to recording information. In an electrostatic recording device that selectively transfers the developer, which has been applied and has been conveyed to a recording unit where the recording electrode and the counter electrode face each other, to the counter electrode side, on the upstream side of the developer conveying direction of the recording unit. At least the surface in contact with the developer is formed of an insulating material having a triboelectrification characteristic of rubbing with the carrier to be charged to the same polarity as the charging polarity of the toner with the carrier.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in FIGS. FIG. 1 is a schematic sectional view showing the overall configuration of a recording apparatus as an embodiment of one of the main points of the present invention. In the figure, reference numeral 1 is a paper feed cassette in which plain papers P are stacked and housed, and is attached to the side of the machine so as to be freely inserted and removed. A paper feed roller 1a is disposed above the leading end of the inserted paper feed cassette 1 so as to be rotatable in the arrow direction. In front of the paper feed roller 1a, an insulating member is formed.
The lower transport guide plates 2a and 2b are laid to form a sheet carry-in path. In this paper carry-in path, a pair of standby rolls 3
Is arranged so that the progress of the paper P fed out by the paper feed roller 1a is once stopped to adjust the conveyance posture, and thereafter, it is synchronized with the arrival timing of a recording image described later to the image transfer section T on the downstream side. Re-deliver to.

At the image transfer portion T on the downstream side of the standby roll pair 3, a transfer charger 4 is arranged opposite to the upper peripheral surface of a cylindrical electrode 5 which also serves as an image carrier. The cylindrical electrode 5 serves as a counter electrode of a recording electrode which will be described later, and in this example, the cylindrical electrode 5 is driven and rotated in a counterclockwise direction indicated by an arrow a. A bias power source 5a capable of applying a bias voltage having the same polarity as the charging polarity of the toner in the developer described later is connected to the cylindrical electrode 5. A recording image forming unit U, which will be described later, is installed opposite to the peripheral surface on the opposite side of the cylindrical electrode 5. A toner recording image is formed on the surface of the cylindrical electrode 5 by the recording image forming unit U, and the toner recording image is conveyed to the image transfer portion T with the rotation of the cylindrical electrode 5 and transferred onto the sheet fed again. The configuration of the recording image forming unit U will be described later in detail.

On the downstream side of the image transfer section T, a separation claw 6 is arranged with its tip pressed against the peripheral surface of the cylindrical electrode. And
An air suction type conveyor belt 7 is horizontally stretched on the downstream side of the separation claw 6 to suck the back surface of the sheet separated from the peripheral surface of the cylindrical electrode 5 by the separation claw 6 after the transfer of the recorded image is completed. While carrying out, it conveys toward the fixing device 8 provided in the front. The fixing device 8 is composed of a heating roll 8a and a pressure contact roll 8b, and heat-fixes the toner image when the paper is sandwiched and conveyed between the rolls. The fixed sheet is discharged and stacked on the discharge tray 10 from the discharge port 9 in a face-down state with the image side facing down.

As described above, in the recording apparatus of this example,
Since the entire sheet transport path from sheet feeding to sheet ejection is formed in a substantially straight shape, the sheet passing operation is generally smooth, and sheet defects such as image defects and jams are unlikely to occur.
In addition, there is an advantage that a face-down sheet discharge state that does not require page alignment, which is preferable for the recording apparatus, can be obtained by the straight sheet passage.

The detailed structure of the recording image forming unit U will be described below. As shown in FIG. 2, the recording image forming unit U generally includes a toner storage tank 11 for storing replenishment toner t0, a development recording tank 12 having a recording unit and a developing unit, and the like. A stirring blade 11 a is rotatably arranged in the toner storage tank 11. A two-component developer is used as the developer. In this example, a two-component magnetic developer in which a magnetic carrier having a negative (-) triboelectricity and a positive (+) insulating toner are mixed at a predetermined ratio is used. ..

At the bottom of the developing / recording tank 12, a horizontal developer circulation path 13 shown in FIG. 3 is formed. In FIG. 3, in the pair of parallel longitudinal paths 13a and 13b in the horizontal circulation path 13, a pair of auger rolls 14a,
14b is rotatably installed. Each auger roll 14
a and 14b have a plurality of spiral blades 14a2 and 14b2 provided upright on the peripheral surface of the shafts 14a1 and 14b1, respectively, and reverse feed blades 14a3 and 14b3 having opposite spiral directions provided upright at one end of each of them. (See perspective view of FIG. 5). And, so that the respective reverse feed blades 14a3, 14b3 are located on the opposite sides,
The auger rolls 14a, 14b are connected to the longitudinal paths 13a, 13
Place each in b. These pair of auger rolls 14
The a and 14b are driven and rotated in directions opposite to each other as indicated by arrows B and C and in a direction in which the developer is conveyed toward the reverse feed blades 14a3 and 14b3. As a result, the reverse feed blade 14
At the corners where a3 and 14b3 are provided, the conveying forces in the opposite directions, which face each other, collide with each other, and the developer is ejected at a right angle and flows to the other longitudinal path side. In this way, the developer can be circulated and flowed while being stirred in the direction indicated by the broken arrow D in this example, and at this time, the developer can be sufficiently tribocharged. By changing the material and shape of the auger rolls 14a and 14b, the amount of charge required for the developer can be sufficiently frictionally charged.

The central portion of the horizontal circulation path 13 configured as described above is surrounded by a wall S so that the circulating developer does not enter.
A space S surrounded by w is formed. Then, as shown in FIG. 2, the auger roll 14 closer to the toner storage tank 11 is provided.
A replenishment port 11b for the replenishment toner t0 is formed in the upper part of a along the axial direction of the auger roll 14a.

In FIG. 2, above the auger roll 14b, a developing sleeve 15 as a developer carrying member that forms a vertical conveying path for the developer is installed extending in the horizontal direction. The developing sleeve 15 rotatably incorporates a magnet roll 16 as a developer conveying means therein, and is arranged so as to face the cylindrical electrode 5 described above. Magnet roll 16
Different magnetic poles are alternately magnetized on the peripheral surface of the developer. By rotating the magnet roll 16 in the counterclockwise direction indicated by the arrow E, the developer d is vertically moved along the peripheral surface of the developing sleeve 15. The sheet is conveyed in the clockwise direction indicated by the dashed arrow.

The cylindrical electrode 5 is formed near the peripheral surface of the developing sleeve 15.
A doctor blade 12a as a layer thickness regulating member for regulating the layer thickness of the conveyed developer d to an appropriate thickness is provided on the upstream side in the toner conveying direction of the facing portion close to the peripheral surface. is there. A toner scattering prevention plate 12b is arranged above the doctor blade 12a. The toner scattering prevention plate 12b is provided in order to prevent a problem that the developer conveyed downstream due to the layer thickness regulation by the doctor blade 12a scatters to the outside of the recording image forming unit U and stains the image. In this example, the upper end of the tank wall of the development recording tank 12 is bifurcated and formed on the doctor blade 12a and the toner scattering prevention plate 12b, respectively.

A recording unit W for forming a toner recording image on the peripheral surface of the cylindrical electrode 5 is constructed as follows on the downstream side of the toner layer thickness regulating unit in the toner conveying direction. As shown in FIG. 4, in this example, a step G is formed on the peripheral surface of the developing sleeve 15 at a position closest to the peripheral surface of the cylindrical electrode 5. The step G is formed over the entire width direction of the peripheral surface of the developing sleeve 15.

The developing sleeve 1 on the upstream side from the step G described above.
A recording electrode sheet 17 having a large number of recording electrodes is laid on the surface of the five circumferences. In the recording electrode sheet 17, as shown in FIG. 5, a large number of recording electrode wires 17a extend in parallel with each other in the sheet longitudinal direction along the circumferential direction of the peripheral surface of the developing sleeve 15 and at a predetermined fine pitch. They are arranged side by side in the width direction (toner conveyance path width direction: main scanning direction). The number of recording electrode lines 17a corresponds to the maximum number of data for one main scanning line. Recording electrode sheet 1 of this example
Reference numeral 7 is a flexible printed circuit board (FPC), and a large number of recording electrode lines 17a made of a non-magnetic conductive material are arranged on a base film 17b made of a flexible insulating material in an amount of 40 μm.
Is laid and formed with a density of 84.6 μm pitch (300 DPI) while maintaining the gap.

As shown in FIG. 6 which is an enlarged schematic cross-sectional view of the recording portion W and its vicinity, the recording electrode wire 17a is laid on the base film 17b and is involved in the formation of a recorded image. A protective coat 17c is applied except for the tip region Z. The tip portion Z of the recording electrode wire 17a not covered with the protective coat 17c becomes the recording electrode EL for forming a recorded image. The protective coat 17c is formed in a two-layer structure in which a conductive coat layer 17c2 made of a conductive material is laminated on an insulating coat layer 17c1 made of an insulating material. As a result, the insulation between the recording electrode wires 17c is improved by the insulation coating layer 1
7c1 can be ensured and abrasion of the recording electrode wire 17a due to friction with the developer d carried by the entire protective coat 17c can be prevented. The conductive coat layer 17c2 that contacts the developer d is grounded together with the developing sleeve 15.

When the recording electrode sheet 17 as described above is manufactured, a base film 17b made of a flexible insulating material coated with a copper foil is etched to form a large number of recording electrode lines 17a after patterning. , Insulation coating layer 17c1
Then, the conductive coating layer 17c2 may be sequentially laminated on the region excluding the tip region Z. A protective coat 17c in which a conductive coat layer 17c2 is laminated on the insulating coat layer 17c1 may be formed in advance, and the protective coat 17c may be applied after the recording electrode lines 17a are patterned.

In FIG. 4, in the recording electrode sheet 17 having the above-described structure, the leading ends of the recording electrodes EL formed in parallel are aligned with the step G position, and from this position the developing sleeve 15 is formed.
Is provided over the peripheral surface on the upstream side. This recording electrode EL
The space where the cylindrical electrode 5 and the peripheral surface of the cylindrical electrode 5 face each other is the recording portion W.

In FIG. 2, on the downstream side of the recording portion W in the toner conveying direction, a wall Sw1 on the developer storage tank 12 side is extended by a wall surrounding the central space S of the horizontal circulation path 13 described above. Its tip is brought into contact with the peripheral surface of the developing sleeve 15. As a result, the developing sleeve 1 is not transferred in the recording portion W.
The developer d ′ remaining on the surface of the five circumferences and conveyed along with the rotation of the magnet roll 16 is scraped off onto the replenishment tank side path 13a of the horizontal circulation path 13 so that the developer d ′ becomes the central space S.
It is possible to prevent inconveniences such as intrusion into the inside and direct return to the upstream side along the peripheral surface of the developing sleeve 15 without passing through the horizontal circulation path 13. A flat plate member dedicated to scraping off the residual developer d ′ adhering to the developing sleeve 15 may be provided separately from the peripheral wall of the central space S. In this case, the scraping member may be supported in the vertical direction, the tip may be brought into contact with the peripheral surface of the developing sleeve 15, and the other end may be extended to the bottom of the central space S. Further, if the scraping member is made of a magnetic material, the magnetic force of the magnet roll 16 can be blocked, and a smoother scraping and conveying effect can be obtained.

The recording electrode sheet 17 is aligned at the position where the tip of the recording electrode EL is closest to the peripheral surface of the cylindrical electrode 5 on the peripheral surface of the developing sleeve 15, is laid over about half the peripheral surface on the upstream side, and is horizontally arranged. After pulling it out, lower it vertically,
It extends to the inside of the central space S of the above-mentioned horizontal circulation path. On the vertically extending portion of the recording electrode sheet 17, a plurality of drive circuit elements 18 for applying a recording voltage to each recording electrode EL according to recording data are mounted. Then, as shown in FIG. 5, the recording electrode lines 17a of the above-mentioned recording electrode sheet 17 are connected to each drive circuit element 18 by dividing the recording electrode lines 17a into N lines. In this way, by storing and installing the other end of the recording electrode sheet 17 on which the drive circuit element 18 is mounted in the central space S, the drive circuit element 18 can be protected from dust such as developer and the development recording tank 12 can be protected. The structure is extremely compact.

Next, a recording image forming operation in the electrostatic recording apparatus of this example will be described. In FIG. 2, when the magnet roll 16 is driven and rotated in the direction of arrow E, a rotating magnetic field for rotating each particle of the two-component developer d is formed on the outer peripheral surface of the developing sleeve 15. By this rotating magnetic field,
The developer d in the horizontal circulation path 13b is attracted to the upper developing sleeve 15 side and is conveyed in the direction of the arrow opposite to the rotating direction of the magnet roll 16 while forming a brush on the recording electrode sheet 17. The developer d, which is conveyed upward along the surface of the recording electrode sheet 17, is subjected to the cutting control by the doctor blade 12a, uniformly thinned to a desired layer thickness (the height of the cutting), and reaches the recording portion W. ..

By the way, the following problems are likely to occur in the conventional developer transport path up to the above-mentioned recording section W. In FIG. 8, as in the embodiment of FIG. 6, a step G is formed at a position of the developing sleeve 91 that is closest to the cylindrical electrode 92, and the tip of the recording electrode sheet 93 is stepped by a step G.
And is provided on the peripheral surface of the developing sleeve 91. The recording electrode sheet 93 is formed by patterning a large number of recording electrode lines 93a on a base film 93b and applying an insulating protective coat 93c on the base film 93b except the tip portion Z. The two-component developer d is conveyed on the surface of the insulating protective coat 93c while forming a spike. The two-component developer d is composed of an insulating toner t which is charged positively and is rubbed against each other, and a magnetic carrier c which is negatively charged. Now, it is assumed that the insulating protective coat 93c has a triboelectric charging property of being positively charged by friction with the carrier c. Incidentally, the illustrated state is a state in which a non-image portion is formed, and the voltage applied to the recording electrode EL by the drive circuit element 94 is on the ground potential side.

The carrier c of the developer d is negatively charged by friction with the toner t, but the insulating protection coat 93
When it is conveyed on the surface c, it is rubbed with the surface and newly charged with a positive charge, and the negative charge is neutralized. As a result, the degree of negative charge of the carrier c becomes weak,
Alternatively, when triboelectric charging with the insulating protective coat 93c is remarkable, it may be positively charged. The toner t adheres to the carrier c by the Coulomb force, and this Coulomb force becomes weaker as the negative charge of the carrier c is neutralized and reduced as described above. As a result, the toner t becomes the carrier c.
The toner t is separated from the carrier c and scattered by the centrifugal force and the impact force during the conveyance, and a part ts of the scattered toner adheres to the circumferential surface of the cylindrical electrode 92 by a so-called mirror image force. The other part ts' of the scattered toner is the recording electrode E.
It adheres to L with the same image force and is deposited. This recording electrode EL
The toner ts' accumulated on the carrier c and the recording electrode EL are
Since it serves as an insulating layer that blocks the conduction with the carrier c, even if the carrier c is transported onto the recording electrode EL, the positive charge obtained by friction with the insulating protection coat 93c cannot be leaked. Therefore, the carrier c that has been conveyed onto the recording electrode EL while forming the ears remains weakly negative or positive, and thus even if it comes into contact with the scattered toner ts adhering to the circumferential surface of the cylindrical electrode 92, Cannot be collected. The scattered toner ts that is not collected in the recording portion W becomes toner stains in the non-image portion, that is, background stains, and deteriorates the image quality.

However, in this example, as shown in FIG. 6, the surface layer of the protective coat 17c is grounded as the conductive coat layer 17c2 made of a conductive material.
The above-mentioned inconvenience is surely prevented. In FIG. 6, the ears of the two-component developer d composed of the magnetic carrier c and the insulating toner t are recorded on the surface of the conductive coating layer 17c2 on the recording portion W.
Is being transported to. By the time the ears of the developer d are carried into the recording portion W, the carrier c and the toner t are in friction with each other, and are sufficiently frictionally charged to the above-mentioned charging polarity. That is, the carrier c is negatively charged, the toner t is positively charged, and each of them is sufficiently charged with substantially the same amount of electric charge. Here, the carrier c is the conductive coat layer 17c of the protective coat 17c.
Although it also rubs against the two surfaces, since the conductive coat layer 17c2 is grounded, almost no electric charge is generated by friction with the surface of the conductive coat 17c2. Therefore, the toner t of the carrier c
There is no fear that the negative charge obtained by the triboelectric charging with and will decrease, and the carrier c and the toner t are carried into the recording unit W in a state in which the necessary and sufficient initial charge is held. Therefore, even if the developer d is subjected to the centrifugal force or the impact force caused by the conveyance during the conveyance, the toner t and the carrier c retain a sufficient electric charge as described above, and the strong Coulomb force due to the electric charge causes The toner t is securely held by the carrier c and does not come off. In this way, the occurrence of background stain due to the scattered toner is reliably prevented.

In FIG. 4, in the recording portion W, the recording electrode E
The peripheral surface of the cylindrical electrode 5 is rotationally moved with respect to L while maintaining a predetermined minute gap, and the thinned developer d is carried in between the electrodes. In the recording portion W, the drive circuit element selectively applies the recording voltage to each recording electrode EL according to the recording data as described above. In this case, when the 1-bit recording data is, for example, “H”, a voltage of +200 V is applied to the corresponding recording electrode EL in this example.
A bias voltage of +50 V in this example is applied to the cylindrical electrode 5 facing the recording electrode EL by the bias power source 5a. Therefore, an electric field based on the potential difference of +150 V is formed from the recording electrode EL toward the circumferential surface of the cylindrical electrode 5. The bristles of the developer d pass through the recording portion W in which such an electric field is formed while being in contact with the peripheral surface of the cylindrical electrode 5. At this time, the positively charged toner t in the developer d is subjected to an electric field force to move the toner t to the lower potential side. This electric field force is larger than the Coulomb force with the carrier c described above, and therefore only the toner t of the ears of the developer d carried on the recording electrode EL to which the voltage of +200 V is applied is selectively selected. It is transferred to the surface and one black dot Dt is formed.

The schematic enlarged sectional view of FIG. 6 shows the state of the recording portion W when the non-image portion (background portion) is formed. As shown in the figure, when the 1-bit recording data is "L", the recording voltage applied to the recording electrode EL by the drive circuit element 18 is switched to the ground potential side. As a result, a potential difference of +50 V is formed from the cylindrical electrode 5 toward the recording electrode EL having the ground potential, and the positive-polarity toner t is subjected to the electric field force attracted toward the recording electrode EL having the lower potential. Therefore,
When the ears of the developer d pass through the recording portion W, the toner t comes into contact with the peripheral surface of the cylindrical electrode 5, but the toner t is attracted to the recording electrode EL side by both Coulomb force and electric field force. It does not adhere to the peripheral surface of the cylindrical electrode 5 due to the force. In this way, the toner t passes through the recording portion W while adhering to the carrier c, so that the occurrence of background stain is more reliably prevented.

In FIG. 4, in the recording section W, the potential of each recording electrode EL is +20 depending on the input recording data as described above.
The toner recording image is formed on the surface of the cylindrical electrode 5 by selectively controlling it to 0 V and the ground potential, and the toner recording image is composed of black dots Dt and has no background stain. The bristles of the developer d ′ that have passed through the recording portion W reach the step G on the immediately downstream side, and quickly move away from the circumferential surface of the cylindrical electrode 5. As a result, it is possible to surely avoid the problem that the toner recording image formed on the circumferential surface of the cylindrical electrode 5 is disturbed by the ears of the developer d that has passed through the recording portion W.

In FIG. 1, the toner recording image formed on the surface of the cylindrical electrode 5 is conveyed to the image transfer portion T along with the rotation of the cylindrical electrode 5 in the counterclockwise direction (a), and the timing is measured by the standby roll pair 3 here. And is transferred onto the paper that is re-fed. The bias voltage of the bias power source 5a may be changed to adjust the density of the toner recording image. In that case, the appropriate adjustment range is about 0 to +50 V, and the closer to 0 V, the higher the image density.

In FIG. 2, a step G passing through the recording portion W is formed.
The ears of the developer d ′ that have passed through (see FIG. 4) move to the downstream side with the rotation of the magnet roll 16, are scraped off the surface of the developing sleeve 15 by the scraping wall Sw1, and fall to the auger roll 14a, and the replenishment port Toner t supplied from 11b
Stir-mixed with 0. With the rotation of the auger roll 14a, the developer d'returned and returned and the replenishment toner t0 are circulated and conveyed while being mixed and stirred. In FIG. 3, the developer that is circulated and conveyed in the direction of the broken arrow D is conveyed again in the vertical direction by the rotating magnetic field of the magnet roll 16 that extends above when it is conveyed through the longitudinal path 13b on the non-replenishment side. It

As described above, the developer d'conveyed to the downstream side through the recording section W is scraped off onto the horizontal circulation path 13 and smoothly returned to the upstream side while being stirred through the horizontal circulation path 13. Then, the toner recording image is formed again. When the developer d is circulated and conveyed while being stirred in the horizontal circulation path 13, the toner and the carrier rub against each other, and each of them is sufficiently triboelectrically charged to each of positive and negative polarities.

Next, an embodiment based on the other main point of the present invention will be described with reference to FIG. The same components as those in the above-described embodiment based on one of the points are given the same reference numerals and the description thereof will be omitted. In the embodiment shown in FIG. 7, the recording electrode sheet 19 is formed by patterning the recording electrode lines 19a on the base film 19b, and then the insulating protective coat 19c made of a single layer of insulating material except the tip portion Z is formed thereon. It is constructed by being attached. As the developer d, as in the above-described embodiment, the toner t that is rubbed against each other to be positively charged
Two-component developer d consisting of a negatively charged carrier c
Is used. Then, as an insulating material of the insulating protective coat 19c, the carrier c is rubbed to charge it negatively (the insulating protective coat itself is charged positively), and preferably it is rubbed with the toner t to make it positive. A material having a triboelectrification characteristic that is electrically charged (the insulating protection coat 19c itself is negatively charged) is selected. That is, a material located between the material of the toner t and the material of the carrier c on the triboelectric series is selected. As a result, when the developer d is transported on the surface of the insulating protective coat 19c serving as the developer transporting route, the carrier c rubs against the surface of the insulating protective coat 19c and is negatively charged. Since the carrier c rubs against the toner t and is negatively charged, it is more strongly negatively charged while being transported on the surface of the insulating protective coat 19c. Therefore,
The positively charged toner t can be securely attached and held by the strong Coulomb force. Therefore, when the developer d is conveyed to the recording portion W, it is possible to prevent the toner t from separating from the carrier c and scattering due to centrifugal force or the like, and it is possible to obtain a good recorded image without background stain. Further, even if the surface of the insulating protective coat 19c and the toner t come into contact with each other during the conveyance of the developer d, the toner t is positively triboelectrically charged due to the relationship in the triboelectric charging series between the two, so that the Coulomb force with the carrier c is increased. It becomes stronger and the occurrence of background dirt is prevented more reliably.

It should be noted that the present invention should not be limited to the above specific embodiments, and various modifications can be made within the technical scope of the present invention.

For example, as the developer, it is also possible to use a two-component developer in which the toner has a negative (-) chargeability and the carrier has a positive (+) chargeability. In that case, the bias voltage applied to the recording electrode and the counter electrode may have a negative (-) polarity. When the protective coat is formed of an insulating material, an insulating material that rubs against the carrier and charges it to a positive polarity may be selected.

[0036]

As described above in detail, according to the present invention, the member forming the surface portion in contact with the developer on the upstream side of the recording portion where the recording electrode and the counter electrode face each other is made of a conductive material. When it is formed by the above method and grounded, or when it is formed by an insulating material, the developer is conveyed to the recording section by selecting an insulating material having a characteristic of being rubbed with the carrier and being charged with the same polarity as the toner. It is possible to reliably prevent the inconvenience that the toner detaches from the carrier and adheres to the counter electrode before. As a result, it is possible to stably obtain a high-quality recorded image without background stains.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the overall configuration of an electrostatic recording device as an embodiment of one of the main points of the present invention.

FIG. 2 is a schematic cross-sectional view showing a recording image forming unit and its peripheral configuration in the electrostatic recording apparatus.

FIG. 3 is a plan sectional view showing a horizontal circulation path of the recording image forming unit.

FIG. 4 is a schematic cross-sectional view showing a configuration of a recording unit and its vicinity in the electrostatic recording device.

FIG. 5 is a perspective view showing the entire recording image forming unit.

FIG. 6 is a schematic enlarged cross-sectional view showing a detailed configuration in the vicinity of the recording unit and a developer conveying operation.

FIG. 7 is a schematic enlarged cross-sectional view showing a configuration of a recording unit and its vicinity as an embodiment of the other main point of the present invention.

FIG. 8 is a schematic enlarged cross-sectional view showing a configuration near a recording unit in a conventional electrostatic recording device.

[Explanation of Codes] 4 Transfer Charger 5 Cylindrical Electrode 5a Bias Power Supply (Cylindrical Electrode Side) 11 Developer Reservoir 12 Development Recording Tank 13 Horizontal Circulation Path 14a, 14b Auger Roll 15, 20, 91 Development Sleeve 16 Magnet Roll 17, 19, 93 recording electrode sheet 17a, 19a, 93a recording electrode wire 18,94 drive circuit element EL, EL 'recording electrode S central space U recording image forming unit W recording unit

Claims (3)

[Claims] 1. A developer transporting means for transporting a developer along a predetermined developer transporting path, a recording electrode arranged in parallel on the developer transporting path with a space therebetween, and a recording electrode facing the recording electrode. A recording unit having a counter electrode, a two-component developer containing a toner and a carrier is used as the developer, a voltage is applied to each of the recording electrodes according to recording information, and the recording electrode and the counter electrode face each other. In an electrostatic recording device for selectively transferring the developer conveyed to the counter electrode side, at least a surface in contact with the developer on the upstream side in the developer conveying direction of the recording portion is formed of a conductive material. An electrostatic recording device characterized by being grounded. 2. A developer transporting means for transporting a developer along a predetermined developer transporting path, a recording electrode arranged in parallel on the developer transporting path with a space therebetween, and a recording electrode opposed to the recording electrode. A recording unit having a counter electrode, a two-component developer containing a toner and a carrier is used as the developer, a voltage is applied to each of the recording electrodes according to recording information, and the recording electrode and the counter electrode face each other. In an electrostatic recording device that selectively transfers the developer conveyed to the counter electrode side, at least a surface in contact with the developer on the upstream side in the developer conveying direction of the recording unit is rubbed with the carrier. An electrostatic recording apparatus, wherein the toner is formed of an insulating material having a frictional charging characteristic that charges the toner to the same polarity as the carrier. 3. The electrostatic recording apparatus according to claim 2, wherein the position of the insulating material on the triboelectric series is between the toner and the carrier.