JPH0542711A - Electrostatic recording device - Google Patents

Abstract

PURPOSE:To provide an electrostatic recording device wherein inconvenience of disturbance of formed record image caused by recovery developer can be prevented and record image with high quality having high resolution without image disturbance can be formed stably. CONSTITUTION:A step difference G is formed on a position deviated from a position facing a position Nc most approximate to a developing sleeve 15 on a peripheral surface of a cylindrical electrode 5 by a fine distance R upstream in toner conveying direction. The magnitude of the step difference G is set to be larger than height of head of magnetic toner to be formed at a downstream of a recording unit W. A record electrode sheet 17 is attached covering a peripheral surface at the upper stream from the recording unit W on the peripheral surface of the developing sleeve 15 and a tip of a recording electrode EL uncovered with an insulating protective coat 17c at the tip of the record electrode sheet 17 is positioned in the step difference G.

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.

In the above electrostatic recording system, a magnetic developer such as a magnetic toner is usually used as the developer, and the magnetic field generating means such as a magnet roll forms the ears of the developer while the developer is applied to the electrode facing portion. Transport. In that case, the toner recording image formed on the counter electrode in the electrode facing portion tends to be disturbed by the ears of the developer remaining on the recording electrode side.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides an electrostatic recording apparatus capable of stably forming a high-quality recorded image without image distortion for a long period of time. The purpose is to do.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention comprises a developer carrying member laid along a predetermined path,
A developer carrying means for carrying a developer along the surface of the developer carrying member, recording electrodes arranged in parallel on the surface of the developer carrying member, and a counter electrode arranged opposite to the recording electrode. In the electrostatic recording apparatus, which has a voltage applied to each of the recording electrodes according to recording information and selectively transfers the conveyed developer to the counter electrode side, The developer carrying member and the surface of the counter electrode are positioned so as to be shifted by a minute distance upstream from the position where the counter electrode surface is closest to the developer carrying member, and a step which falls toward the downstream side at a position corresponding to the tip of the recording electrode of the developer carrying member is formed. The point is that the size of the step is set to be larger than the height of the ears formed by the developer while being formed.

[0006]

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 cross-sectional view showing the overall configuration of a recording apparatus as an embodiment 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, upper and lower transport guide plates 2a and 2b made of an insulating member are laid to form a paper carry-in path. A standby roll pair 3 is arranged in the sheet carrying-in path, and after temporarily stopping the progress of the sheet P fed by the sheet feeding roller 1a to adjust the conveying posture, the image transfer unit T on the downstream side is provided. The sheet is re-fed so as to be synchronized with the arrival timing of the recorded image described later.

In the image transfer portion T on the downstream side of the standby roll pair 3, a transfer charger 4 is arranged so as to face 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 portion T, a separating 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.

Now, the detailed structure of the recording image forming unit U will be described. As shown in FIG. 2, the recording image forming unit U is roughly composed of a developer storage tank 11 for storing a replenishment developer d0, a developing recording tank 12 having a recording means and a developing means, and the like. A stirring blade 11a is rotatably arranged in the developer storage tank 11. In this example, the developer is a one-component developer containing at least an insulating resin, magnetic fine powder and colorant particles, and an insulating magnetic toner having a negative (−) triboelectrification polarity is used. As the developer, it is possible to use a two-component magnetic developer in which a magnetic carrier and an insulating toner are mixed in a predetermined ratio.

At the bottom of the developing / recording tank 12, a horizontal circulation path 13 for the developer 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. 6). 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 constructed 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 developer storage tank 11 is provided.
A replenishment port 11b for the replenishment magnetic toner d0 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 with its axis extending horizontally. 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. Different magnetic poles are alternately magnetized on the circumferential surface of the magnet roll 16, and the magnetic toner d is driven along the circumferential surface of the developing sleeve 15 by driving and rotating the magnet roll 16 in the counterclockwise direction indicated by arrow E. And is conveyed in a clockwise direction indicated by a vertical broken arrow.

The cylindrical electrode 5 is formed near the peripheral surface of the developing sleeve 15.
A doctor blade 12a for restricting the height of the bristles of the magnetic toner d being conveyed to a predetermined height is arranged on the upstream side in the toner conveying direction of the facing portion close to the peripheral surface.
A toner scattering prevention plate 12b is arranged above the doctor blade 12a. This toner scattering prevention plate 12b
Is provided to prevent the inconvenience that the developer conveyed downstream due to the layer thickness regulation by the doctor blade 12a is scattered outside 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 arranged as follows on the downstream side of the toner spike height regulating unit in the toner conveying direction. As shown in FIG. 4, the cylindrical electrode 5 is formed on the peripheral surface of the developing sleeve 15.
A step G is provided at a position upstream of the position Nc closest to the developing sleeve 15 side on the peripheral surface by a minute distance R.
Has been formed. For example, when the outer diameter of the cylindrical electrode 5 is 20 mm and the outer diameter of the developing sleeve 15 is 23 mm, the minute distance R is preferably about 1 mm. The step G is formed over the entire widthwise direction of the peripheral surface of the developing sleeve 15.

The size of the step G is set so that the residual magnetic toner conveyed to the downstream side of the step G can prevent disturbance of the toner recording image formed on the peripheral surface of the cylindrical electrode 5 as described later. The height is set larger than the height of the spike formed by d '. The ears of the residual magnetic toner d ′ on the downstream side of the step, which causes the image disturbance, are formed as follows.

As shown in FIG. 5, the ears of the magnetic toner d'are
It is formed at a position facing the magnetic pole of the magnet roll 16 on the surface of the developing sleeve 15 on the downstream side of the step G. in this case,
First, the first magnetic toner particle d1 'is attracted and held at the position on the magnetic pole by the magnetic gradient force Fm1 of the magnet roll 16. Since the magnetic toner particles d1 'are magnetic substances, they concentrate the magnetic force lines. As a result, the magnetic toner d1 '
A magnetic gradient force Fm2 stronger than the magnetic gradient force Fm1 is formed on the upper side, and the second magnetic toner particles d2 'are held thereon. Similarly, magnetic toner particles d3 ', ... dn', d (n + 1) 'are sequentially stacked on the second magnetic toner d2' to form ears. However, the strength of the magnetic field generated by the magnet roll 16 becomes weaker as it is separated from the magnetic pole. Therefore, when the height of the magnetic toner d'has reached a certain height, the magnetic gradient force of the magnetic toner d'becomes small even if a large number of magnetic force lines are focused, and the height of the magnetic toner d'has a constant height. Does not grow any further. That is, for example, when n magnetic toner particles d1 'to dn' are connected to form a spike having a height h, the (n + 1) th magnetic toner particle d is formed.
The magnetic gradient force Fm (n + 1) acting on (n + 1) 'is Fm1> Fm (n + 1). As a result, the (n + 1) th magnetic toner particle d (n
+1) is held on the surface of the developing sleeve 15 by a stronger magnetic gradient force Fm1, and the height of the spikes of the magnetic toner d is determined by h.

As can be seen from the above-mentioned formation mechanism of the magnetic toner ears, the height h of the ears of the magnetic toner d depends on the magnetization of the magnetic toner and the particle size of the magnetic toner particles (the degree of focusing of magnetic force lines varies depending on the particle size). , And the number of magnetic poles of the magnet roll 16 and its magnetic flux density. Therefore, the larger the magnetization and particle size of the magnetic toner d ', the greater the magnetic toner d'.
Since the height h of the spikes becomes large, the step G
Also needs to be set larger than that. Also, the smaller the number of magnetic poles and the magnetic flux density of the magnet roll 16, the height h of the spikes
Therefore, the size of the step G needs to be increased correspondingly.

Returning to FIG. 4, a recording electrode sheet 17 having a large number of recording electrodes is laid on the peripheral surface of the developing sleeve 15 upstream from the step G. In the recording electrode sheet 17, as shown in the perspective view of FIG. 6, a large number of recording electrode wires 17a are extended 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. Sheet width direction at pitch (toner conveyance path width direction:
They are arranged side by side in the main scanning direction). The number of recording electrode lines 17a corresponds to the maximum number of data for one main scanning line. The recording electrode sheet 17 of this example is composed of 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 to have a thickness of 40 μm. With a gap of 84.6
It is laid and formed with a density of μm pitch (300 DPI).

On the recording electrode line 17a, except for the tip region Z related to the formation of a recorded image, the insulating protective coat 17 is formed.
c is attached. The insulating protection coat 17c is made of an electrically insulating material and ensures insulation between the recording electrode wires 17a, and at the same time, the recording electrode wires 17a due to friction with the magnetic toner.
It is provided to prevent abrasion of the. The tip portion Z of the recording electrode wire 17a not covered with the insulating protection coat 17c is
It becomes a recording electrode EL that forms a recorded image. Recording electrode EL
When the insulating protection coat 17c is also applied on the upper surface, unnecessary charges are accumulated on the insulating protection coat 17c due to friction with the magnetic toner and cause image defects such as scumming. However, the recording electrode EL is exposed as in this example. By doing so, such an inconvenience can be prevented, and the electric field necessary for forming a recorded image can be efficiently formed.

When the recording electrode sheet 17 having the above-mentioned structure is manufactured, a base film 17b made of a flexible insulating material coated with a copper foil is subjected to an etching process to form a large number of recording electrode wires 17a in a pattern. After that, the insulating protection coat layer 17c may be applied to the region excluding the tip region Z.

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. The inter-electrode distance L of the recording portion W is preferably as small as possible for forming a high-resolution recorded image with sharp dots, and is usually set to about 50 μm.

In FIG. 2, on the downstream side of the recording section W in the toner conveying direction, a wall Sw1 on the developer storage tank 12 side is extended by a wall that surrounds 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 magnetic toner d ′ remaining on the surface of the fifth circumference 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, and the magnetic toner d ′ enters the central space S. This prevents the inconvenience of being directly returned to the upstream side along the peripheral surface of the developing sleeve 15 without passing through the horizontal circulation path 13. Note that a flat plate member dedicated to scraping off the residual magnetic toner 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 is supported in the vertical direction, and the front end is the developing sleeve 1.
It is sufficient to bring them into contact with the surface of the five circumferences and extend the other end 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 arranged such that the recording electrode EL tips are aligned with the step G, and is laid over the peripheral surface of about half of the upstream side from this, and is pulled out in the horizontal direction and then vertically lowered.
It extends to the inside of the central space S of the above-mentioned horizontal circulation path. A plurality of drive circuit elements 18 for applying a recording signal voltage to each recording electrode EL according to recording data are mounted on a vertically extending portion of the recording electrode sheet 17. 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 the magnetic toner particles is formed on the outer peripheral surface of the developing sleeve 15. Due to this rotating magnetic field, the magnetic toner d in the horizontal circulation path 13b is moved upward to the developing sleeve 15
It is attracted to the 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 magnetic toner d, which is conveyed upward along the surface of the recording electrode sheet 17, is regulated by the doctor blade 12a to a predetermined height, and heads toward the recording portion W. During this conveyance, the magnetic toner d is charged to a negative (-) polarity due to friction between the magnetic toners or the surface of the insulating protective coat 17c of the recording electrode sheet 17 which serves as a developer conveyance path.

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 L, and the doctor blade 12 is interposed between the electrodes.
The ears of the magnetic toner d whose ears have been cut off by a are carried in. In the recording portion W in such a state, each recording electrode EL
On the other hand, as described above, the drive circuit element selectively applies the recording signal voltage according to the recording data. Now, for example, when 1-bit recording data is "H" (ON), one black dot is formed.
It is assumed that an ON signal voltage of 0V is applied. In this case, a bias power source 5a is attached to the cylindrical electrode 5 facing the recording electrode EL.
Thus, a bias voltage having the same polarity as the triboelectric charging polarity of the magnetic toner d is applied. In the case of this example, since the triboelectrification polarity of the magnetic toner d is negative (-), a negative bias voltage is applied and the voltage is set to -50V. Therefore,
A developing electric field based on the potential difference of 150 V is formed from the cylindrical electrode 5 toward the recording electrode EL. The ears of the magnetic toner d pass through the recording portion W in which such a developing electric field is formed while contacting with the peripheral surface of the cylindrical electrode 5. At this time, the magnetic toner d, which is negatively charged, is subjected to an electric field force to move it to a higher potential. Therefore, only the magnetic toner d carried on the recording electrode EL to which the ON signal voltage of −200 V is applied is selectively transferred to the surface of the cylindrical electrode 5.

At the time when an ON signal voltage of -200 V is applied to the recording electrode EL, as shown in FIG. 7A, the magnetism transferred to the circumferential surface of the cylindrical electrode 5 over the range of the distance Z in the sub-scanning direction. Toner d ″ is attached. The ON signal voltage for forming one black dot is, as shown in FIG.
It is applied over the dot recording period). The distance SL that the peripheral surface of the cylindrical electrode 5 moves during this time Tw is SL = Tw.VD, where VD is the peripheral surface moving speed of the cylindrical electrode 5. Therefore, after the time Tw, as shown in FIG. 7B, the magnetic toner d ″ transferred and attached to the circumferential surface of the cylindrical electrode 5 is transferred.
The front portion df ″ over the distance SL within the distance is carried out from the recording portion W as the cylindrical electrode 5 rotates.

As shown in FIG. 8, after the ON signal voltage corresponding to the ON recording data is applied for the time Tw, if the next recording data is OFF, the recording signal voltage is the ground potential. Switched to off signal voltage. As a result, in FIG. 7B, the potential difference of the corresponding recording voltage EL from the cylindrical electrode 5 becomes −50V. as a result,
A recovery electric field for reversely transferring the transfer magnetic toner d ″ (negative polarity) to the recording electrode EL side is formed in the recording portion W, and the rear part d of the transfer magnetic toner d ″ remaining in the recording portion W is formed.
Only r ″ ((Z−SL)) is collected on the recording electrode EL side. Therefore, what remains on the circumferential surface of the cylindrical electrode 5 is the recording portion W.
Only the front magnetic toner df ″ that has been carried out from
This forms one black dot Dt (see FIG. 4).

In FIG. 4, according to the present invention, based on the present invention, the tip position of the recording electrode EL is shifted from the position facing the closest position Nc on the circumferential surface of the cylindrical electrode 5 to the upstream side by a minute distance R. The one black dot Dt described above is sharply formed. This is because by shifting the tip of the recording electrode EL by a minute distance R, the electric field of the portion forming the front and rear ends of the dots in the sub-scanning direction (downstream end of the electric field) can be formed to the maximum strength. This is because the so-called sharpness at the front and rear ends of the dots in the sub-scanning direction is improved.

The formed 1 black dot Dt corresponds to the cylindrical electrode 5
Is conveyed to the downstream side with the rotation of. On the other hand, the residual magnetic toner d ′ that has not transferred is carried out to the downstream side of the recording unit W and forms the ears by the mechanism described above. The ears formed by the residual magnetic toner d'may disturb the recorded image formed of the black dots Dt formed on the circumferential surface of the cylindrical electrode 5. However, in the embodiment based on the present invention, as in this embodiment, the step G having a head larger than the height h of the spikes is formed immediately downstream of the recording portion W, so that the tips of the spikes are black dots Dt.
The inconvenience that the printed image is not disturbed without disturbing the recording medium is reliably prevented.

In FIG. 1, the toner recording image formed on the surface of the cylindrical electrode 5 is conveyed to the image transfer portion T together 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, an appropriate adjustment range is about 0 to -50V, and the closer to 0V, the higher the image density.

In FIG. 2, a step G passing through the recording portion W is formed.
The bristles of the residual magnetic toner d ′ that have passed through (see FIG. 4) move to the downstream side as the magnet roll 16 rotates, and are scraped off from the surface of the developing sleeve 15 by the scraping wall Sw1 and fall to the auger roll 14a for replenishment. The magnetic toner d0 supplied from the port 11b is mixed with stirring. Auger roll 14a
With the rotation of, the magnetic toner d'returned and returned and the replenishing magnetic toner d0 are circulated and conveyed while being mixed and stirred. In FIG. 3, the magnetic toner that is circulated and conveyed in the direction of the broken line 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 side opposite to the supply side. It

As described above, the magnetic toner d'conveyed to the downstream side through the recording section W is scraped off on 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 magnetic toner d is circulated and conveyed while being stirred in the horizontal circulation path 13, it is sufficiently triboelectrified to a predetermined polarity.

It should be noted that the present invention should not be limited to the above-mentioned specific embodiments, and it goes without saying that various modifications can be made within the technical scope of the present invention. For example, although the negative (−) chargeable magnetic toner is used as the developer in the above embodiment, it is also possible to use the positive (+) chargeable magnetic toner. In that case, the bias voltage applied to the recording electrode and the counter electrode may have a positive (+) polarity.

[0035]

As described above in detail, according to the present invention, the recording electrode is located at a position displaced by a minute distance from the position where the counter electrode surface and the developer carrying member are closest to each other to the upstream side in the developer transport direction. The tip is positioned, a step is formed at the position corresponding to the tip of the recording electrode, which drops toward the downstream side, and the size of the step is set to be larger than the height of the spike formed by the developer, thereby sharpening the pixel. It is possible to reliably prevent the inconvenience that the formed toner recording image is disturbed by the collected developer. As a result, it is possible to stably form a high-resolution recorded image having sharp pixels without image distortion for a long period of time.

[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 an explanatory diagram showing a mechanism of formation of developer ears in the recording unit.

FIG. 6 is a perspective view showing the entire recorded image forming unit.

FIG. 7 is an operation explanatory diagram showing stepwise a dot forming operation in the recording unit.

FIG. 8 is a timing chart showing a relationship between a recording signal voltage and a bias voltage.

[Explanation of symbols]

 5 Cylindrical electrode 5a Bias power supply (cylindrical electrode side) 11 Developer storage tank 12 Development recording tank 13 Horizontal circulation path 14a, 14b Auger roll 15 Developing sleeve 16 Magnet roll 17 Recording electrode sheet 17a Recording electrode wire 18 Driving circuit element EL recording electrode G step S central space U recording image forming unit W recording unit

Claims (1)

[Claims] 1. A developer carrying member laid along a predetermined path, a developer carrying means for carrying a developer along the surface of the developer carrying member, and a gap on the surface of the developer carrying member. It has a recording electrode arranged in parallel while keeping it, and a counter electrode arranged so as to face the recording electrode. A voltage is applied to each of the recording electrodes according to recording information, and the conveyed developer is transferred to the counter electrode side. In the electrostatic recording device for selectively transferring, the tip of the recording electrode is displaced by a minute distance to the upstream side in the developer transport direction from the position where the developer carrying member and the surface of the counter electrode are closest to each other, and the developer is An electrostatic recording apparatus characterized in that a step is formed at a position corresponding to the tip of the recording electrode of the carrier member, the step falling toward the downstream side, and the size of the step is set to be larger than the height of the brush formed by the developer. ..