JPH0420977A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To stably form a recording image having high resolution without wearing a recording head by applying a recording voltage on an electrode opposing part where a recording electrode opposes to a cylindrical electrode, and selectively transfer a developer carried to the electrode opposing part by a developer carrying means to the side of the cylindrical electrode. CONSTITUTION:When an alternating current is energized to an energizing coil, a traveling-wave magnetic field moving in the direction of the arrow (A) is formed on the outer periphery of the region where the energizing coil is disposed of a recording unit Uw, and magnetic toner (dt) is carried in the direction of the arrow (B) opposite to the direction of the (A) while forming nap. The carried magnetic toner (dt) whose nap is cut and regulated to a prescribed thickness by a doctor blade 18, and then, reaches a recording part W. A recording part W. A recording electrode wire is arrayed and laid from the recording part W to its upstream side, and a driving circuit element 21 selectively applies the recording voltage according to recorded data with respect to each recording electrode wire. The electrostatically charged magnetic toner (dt) is moved to a high potential side, so that only the magnetic toner (dt) on the recording electrode wire on which the voltage is applied is selectively transferred to the surface of the cylindrical electrode 5, on the recording part W, and a black dot is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a non-contact electrostatic recording device that forms an electrostatically recorded image without bringing a recording head into contact with a recording medium.

[Prior art and its problems]

Conventionally, a multi-stylus printer is well known as one of the electrostatic recording devices.This multi-stylus printer has a recording head made up of a large number of needle-shaped electrodes (styli) arranged at minute intervals, and converts image signals into Accordingly, a high voltage is selectively applied to each needle-shaped electrode to form an electrostatic latent image by directly discharging it onto the paper.In such a multi-stylus printer, the tip of the needle-shaped electrode and the paper surface are If the interval between the
A gap layer is provided on the surface of the paper, and the gap layer and the needle-shaped electrode are brought into sliding contact to ensure a minute gap.

However, this multi-stylus printer has the disadvantage that the needle-like electrodes are worn out because the paper is always in sliding contact with the tips of the needle-like electrodes.

[Purpose of the invention]

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide an electrostatic recording device that can stably form high-resolution recorded images without causing wear on the recording head. .

[Key points of the invention]

The above purpose is to arrange an excitation coil along the back surface of a developer conveyance body made of a non-magnetic material fixedly laid so that the surface becomes a developer conveyance path, and to supply multiple phases of current with different phases to the excitation coil. a developer conveying means that is energized to convey the developer by forming a magnetic field that moves in waves along the surface of the developer conveying body; and a plurality of recording electrodes on the surface of the developer conveying body in a direction perpendicular to the developer conveying direction. Recording means arranged in parallel and comprising a drive circuit installed inside the developer conveying means for outputting a recording voltage to each of the recording electrodes in accordance with input recording information, and facing the recording electrodes with a predetermined gap maintained therebetween. Leave the arranged cylindrical electrode overnight,
By applying the recording voltage to the electrode facing portion where the recording electrode and the cylindrical electrode face each other, the developer transported by the developer transport means to the electrode facing portion is selectively transferred to the cylindrical electrode side. This is achieved by providing an electrostatic recording device characterized by the following.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 11.

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 denotes a paper feed cassette loaded with plain paper P, which is detachably attached to the side of the machine. A paper feed roller 1a is arranged above the tip of the inserted paper feed cassette 1 so as to be rotatable in the direction of the arrow.

In front of the paper feed roller 1a, there is formed a paper transport path defined by upper and lower conveyance guide plates 2a+2b made of insulating members. A pair of standby rolls 3 is disposed in this paper feed path, and after temporarily stopping the advance of the paper P fed out by the paper feed roller 1a and adjusting the conveyance posture, the paper P is transferred to the image transfer section T on the downstream side. The image is re-fed in synchronization with the arrival timing of the recorded image, which will be described later.

In the image transfer section T on the downstream side of the standby roll pair 3, a transfer charger 4 is arranged opposite to a cylindrical electrode 5 which also serves as an image carrier.

In this example, the cylindrical electrode 5 is driven to rotate in the counterclockwise direction indicated by arrow a. A bias power supply 5a capable of applying a bias voltage of -30V is connected to this cylindrical electrode 5. On the opposite circumferential surface of the cylindrical electrode 5, a recording image forming unit l-U, which will be described later, is arranged to face the cylindrical electrode 5. A toner recorded image is formed on the surface of the cylindrical electrode 5 by this recorded image forming unit (U), and as the cylindrical electrode 5 rotates, the toner recorded image is conveyed to the image transfer section T and transferred onto the paper that is being fed again. . The configuration of the recording image forming unit (U) will be described in detail later.

On the downstream side of the image transfer section T, a separating claw 6 is disposed with its tip pressed against the circumferential surface of the cylindrical electrode. An air suction type conveyor belt 7 is stretched horizontally downstream of the separation claw 6, and the separation claw 6 finishes transferring the recorded image.
The back surface of the sheet separated from the circumferential surface of the cylindrical electrode 5 is sucked and conveyed toward the fixing device 8 provided in front of the sheet. The fixing device 8 consists of a heating roll 8a and a pressure roll 8b, and thermally fixes the toner image when the paper is held between the two rolls and conveyed. After the fixing, the sheets are discharged from the discharge port 9 and stacked on the paper discharge tray 10 in a face-down state with the image side facing down.

As described above, in the recording apparatus of this example, the entire paper transport path from paper feeding to paper ejection is formed in a substantially straight shape, so the paper feeding operation is generally smooth, and image defects are avoided. Paper feeding defects such as jams are less likely to occur. It also has the advantage that the above-mentioned straight sheet passing path can achieve a face-down sheet discharge state that does not require page alignment, which is preferable for the recording apparatus.

Here, the detailed configuration of the recording image forming unit (U) will be explained.

The recording image forming unit U generally has an agitation roll 12 and a supply roll 13 rotatably disposed at the bottom of a unit container 11 that stores the developer d, and integrates an image recording means and a developer conveying means. A recording unit U is arranged in such a manner that its recording portion W is exposed through an opening 11a that is open toward the circumferential surface of the cylindrical electrode 5 described above. In this example, the developer d
As a one-component developer containing at least an insulating resin, magnetic fine powder, and colorant particles, an insulating magnetic toner having negative (-) triboelectric charging characteristics is used. In addition, developer d
Alternatively, a two-component developer in which a magnetic carrier and an insulating toner are mixed in a predetermined ratio can also be used.

FIG. 2 is a schematic cross-sectional view showing the recording unit Uw and its peripheral members. The recording unit Us of this example has a columnar body with an oval cross section and extending in the direction perpendicular to the plane of the paper, and has a base 14 made of a high magnetic permeability material such as iron, nickel, or permalloy.
A region other than a part of the outer circumferential surface of is covered with an outer cover member 5 made of a non-magnetic material and whose surface serves as a conveyance path for the magnetic toner d. The peripheral surface of the base body 14 covered with the outer cover member 15 includes
A large number of concave grooves 14a having a V-shaped cross section are formed parallel to each other at equal intervals along the longitudinal axis direction of the base body (direction perpendicular to the plane of the paper). Although FIG. 2 only shows a total of 12 concave grooves 14a, in reality there are more concave grooves 14 than that.
A is formed densely.

The length of each concave groove 14a is set to be longer than the width of the conveyance path defined on the circumferential surface of the outer cover member 15.

A conducting wire lea is buried and laid in each circuit groove 14a,
A coil portion 16 as a part of the excitation coil is formed respectively. As shown in FIG. 3(a), this coil portion 16 is
In this example, it is divided into two groups, A and B, and each group's coil portion 16A,
16B are arranged every other piece. In this case, Figure 3 (
As shown in b), a pair of coil parts 16, 16 adjacent to each other with one coil part 16 in the other group in the same group (for example, consecutive odd-numbered and even-numbered coil parts with the coil part 16Bl) 16AI and 16n) are formed by winding the same conducting wire f6a many times in a predetermined direction across every other pair of recessed grooves 14al l4a. Therefore, every other pair of coil parts 18 in the same group are adjacent to each other.
．． The running directions of the 16 conducting wires lea (based on the winding direction of the coil) are opposite to each other.

In addition, when the coil part 16 is divided into m groups of 3 or more, the coil parts of each group are arranged every (m-1) pieces, and the conductor 1
A pair of concave grooves 14a+1 every (m-1) 6a
4a to form a pair of coil parts of the same set.

As shown in FIG. 4, two types (two phases) of alternating currents IA+IB i A with a phase shift of π/2 are applied to the coil portions 4A of group A and the coil portions 4B of group B configured as described above.工 sin (ωt) ・・・・・・・・・
... (1) i B: I Sin (ωt +
π/2) ...... (2) are respectively energized. By the way, coil part work 6 is A.

B, ...... When divided into m groups of 9M, each coil group has m types (m types) with a phase shift of 77m as shown below.
The alternating currents of the sets) are applied in the order of arrangement.

Coil parts 18A and 16A i A=Isln(ω t) Coil parts 16B and 16B iB=Isln(ω t+ 77m) Coil parts 16M and 16M 1 H= I sin (CLJ t + (n+-1)
)π/m) However, the wave height value (maximum value) ω; 2πf, f: frequency t: time. By applying alternating current to each coil portion 16 as described above, Each partition portion 14b is excited with a magnetic field corresponding to the applied current as shown in FIG. FIG. 5 is a graph showing temporal changes in the excitation magnetic field distribution on the surface of the sleeve 2. FIG. In the graph, the vertical axis represents the sleeve radial component Hr of the excitation magnetic field, and the horizontal axis represents the position on the surface of the sleeve 2. Note that T is the period of the alternating current that is applied. In this example, as described above, the running directions of the conducting wires in the odd-numbered and even-numbered coil portions 16 (for example, 16Al and 16A2) in each set are reversed. Therefore, the coil portions 16 of the same group
If an alternating current with the same phase is passed through the coils, the directions of the magnetic fields excited by the odd-numbered and even-numbered coil portions 16 will be opposite to each other. As a result, the distribution curve of the magnetic field formed on the surface of the sleeve 2 also draws a waveform corresponding to the alternating current as shown in FIG. Since this waveform magnetic field changes with a period T like an alternating current, it results in the formation of a traveling wave magnetic field that travels in the direction C in the figure.

That is, in FIG. 3(a), the waveform magnetic field formed on the surface of the sleeve 2 by all the coil portions 16 travels counterclockwise along the surface of the jacket member 15 at a predetermined speed. As a result, the magnetic toner can be conveyed to the port in the clockwise direction opposite to the traveling direction A of the traveling wave magnetic field. In this case, as shown in FIG. 2, the magnetic toner dt is conveyed while forming spikes of toner corresponding to the lines of magnetic force of the traveling wave magnetic field.

Incidentally, the method of winding the conducting wire to lay and form the excitation coil that generates the traveling wave magnetic field as described above around the circumferential surface of the base body 14 is not limited to the above-mentioned method, but as shown in FIG. One fill 16' may be formed by winding the conducting wire lea around six protruding stripes 14'a provided on the circumferential surface. In addition, as shown in FIG. 7, no unevenness is formed on the peripheral surface of the base, and the conductor
A may be extended and laid in the circumferential direction (! - right angle direction) to form a coil. In this case, the single conductive wire portion 16# from being folded back at one end to being folded back at the other end is This corresponds to the coil portion 16 or coil 16' of the example.

Furthermore, instead of the above-mentioned normal alternating current, an alternating current based on pulse width modulation may be applied.

Returning to FIG. 2, in this example, the base body 14 is separably divided into two parts, and the internal space S is formed by joining the divided base bodies 14A and 14B. Each divided base 1
4A and 14B are individually covered with outer cover members 15A and 15B. Both outer covering members 15A are used to form a flat toner conveyance path.

A bridge member 17 is installed at the joint portion of 15B.

On the upstream side of the toner conveyance path, there is a doctor blade 18 for regulating the toner spikes to an appropriate length to form a toner layer.
It is arranged. The doctor blade 18 of this example is fixed to the side wall of the unit container 11 with its tip brought close to the surface of the outer cover member 15B. On the downstream side of the doctor blade 18, the position where the circumferential surface of the sheathing member 15A is closest to the circumferential surface of the cylindrical electrode 5 with a small gap therebetween becomes the recording section W, where the magnetic toner dt is inputted to the cylindrical electrode 5 according to the recorded data. The toner is selectively transferred to the surface to form a toner recorded image. On the downstream side of the recording section W, a scraping plate 19 is disposed with its tip pressed against the surface of the jacket member 15A. This scraping plate 19 removes residual magnetic toner dt' that has been conveyed without being used in the recording section W to the stirring roll 12 (
(see Figure 1).

As shown in FIG. 8, a recording electrode sheet 20 is placed on the circumferential surface of the outer cover member 15A in an area upstream from the recording section W to the opening in the toner transport direction. . The recording electrode sheet 20 of this example is made of a flexible printed circuit board (FPC), and has a plurality of recording electrode lines 20a extending parallel to each other in the sheet longitudinal direction in the sheet width direction (toner conveyance path width direction). They are formed to extend in parallel on the base film 2Ob at a predetermined fine pitch. The number of recording signal lines 20a is
This corresponds to the maximum number of data for one main scanning line, which will be described later. When manufacturing the FPC recording electrode sheet 20 of this example, a base film 20b made of a flexible insulating material covered with copper foil is etched, and a large number of recording electrode wires 2 are etched.
0a with a pitch of 86μm (300μm, keeping a gap of 40μm)
The pattern is formed at a density of DPI). Although not shown, an insulating film is applied to the surface of the recording electrode sheet 20 to ensure insulation between the recording electrode lines 2Oa.

As shown in FIG. 2, the recording electrode sheet 20 described above has the following characteristics:
The divided bases 14A, 1 are submerged below the bridge member 17.
4B to the internal space S. In the internal space S, recording electrode lines 20a are arranged according to recording data.
A plurality of drive circuit elements 21 are provided to drive the drive circuit. The recording electrode lines 20a of the recording electrode sheet 20 described above are divided into N pieces and connected to these drive circuit elements 21, respectively. From each drive circuit element 21, an input wiring circuit 2
2 is pulled out from the recording unit Uw from the other joint surface of the divided bases 14A and 14B. The input wiring circuit 22 is
It is connected to a recording control section (not shown).The configuration and operation of the drive circuit element 21 will now be described based on the block diagram of FIG. 9.

The drive circuit element 21 consists of a shift register 21a, a data latch 21b, an AND circuit section 21C, a driver section 21d for driving recording electrode lines, and a pull-down resistor section 21e, and these are sequentially connected to the N recording electrode lines assigned to each drive circuit element 21. It is connected via the same number of signal lines as 20a. Assuming that the maximum paper that can be used with the recording device of this example is A4 size, the recording density is 300D as described above.
Since it is PI, the maximum data for one line in the main scanning direction (the width direction of the toner transport path in the recording section W: the direction in which the recording electrode lines 20a are arranged in parallel) is approximately 2400 bits.

The shift register 21a is connected to the recording data and data clock signal input lines 22a and 22b of the input wiring circuit 22 extending from the recording control section (not shown), and the recording data for one line described above is connected to the shift register 21a. is inputted realistically in synchronization with the data clock signal. Here, if one drive circuit element drives 100 recording electrode lines 20a, a total of 24 drive circuit elements 21 will be required.

Each drive circuit element 21 has a cascade connection configuration in which its respective data output terminal 23 is connected to the data input line 22a of the next stage drive circuit element 21, and data exceeding 100 bits is sequentially sent to the next stage drive circuit element 21. Shifted.

The next data latch 21b is connected to an input line 22c for a latch clock signal and a clock signal, and the N pieces of recording data input to the shift register 21a in synchronization with the 7 clock clock signal are transferred to the data latch 21b. latched to.

The AND circuit section 21c includes N AND circuits 21cl to 2.
The strobe signal input line 22d is connected to each AND circuit 21cl to 21cN.

The strobe signal is a signal output to control the ON period when the recording electrode line 20a does not need to be ON for the entire period of a 1-bit recording cycle. each AND
The circuits 21cl to 21cN output a uH signal when both the N-bit recording data output from the data latch 21b and the strobe signal are "H".

The driver section 21d includes N transistors TRI to TR.
N, each base terminal and AND circuit 21cl~
Each output terminal of 21 cN is connected through a resistor. Then, in this example, the emitter terminals of each transistor TRI to TRN are connected to a bias power supply 24 whose output is 1200V.
A collector terminal is connected to each of the N recording electrode lines 20a. The pull-down resistor section 21e includes N pull-down resistors RDI to RDN, and includes a driver section transistor T.
Each collector terminal of RI-TRN is connected to each pull-down resistor RD.
The configuration is such that they are each grounded via the I-RDN.

Therefore, when the output signal from the AND circuits 2101 to 21cN is "H", the base terminal of the corresponding transistor TR becomes "H", and the transistor TR is turned on. As a result, the corresponding signal electrode line 20a is
A bias voltage of V is applied, and one black dot is formed as described later. Conversely, when the output signal of the AND circuits 21cl to 21cN is "L", the corresponding transistor TR is turned off, so the recording electrode line 20a connected thereto becomes the ground potential, and no black dot is formed.

Next, a recorded image forming operation in the recording apparatus of this example will be explained.

In FIG. 2, when the above-mentioned alternating current is applied to the excitation coil, a traveling wave magnetic field moving in the direction of arrow A is formed on the outer peripheral surface of the area where the excitation coil of the recording unit Uw is disposed, and the magnetic The toner d is conveyed in the opposite direction of the arrow while forming ears. The conveyed magnetic toner dt is regulated to have a predetermined thickness by the doctor blade 18, and then reaches the recording section W. At this time, the magnetic toner dt is triboelectrically charged to a negative polarity. Recording electrode wires 20a (see FIG. 8) are laid in parallel on the upstream side of the recording section W.
As described above, the drive circuit element 21 selectively applies a recording voltage to each recording electrode line 20a according to recording data. In this case, when one bit of recording data is "H", the driver transistor TR is turned on, and when a voltage of -200V is applied to the corresponding recording electrode line 20a, the recording electrode
! Since a voltage of -30V is applied to the cylindrical electrode 5 facing the recording electrode line 20a, a potential difference of 150V is created from the cylindrical electrode 5 toward the recording electrode line 20a.

Since the negatively charged magnetic toner dt moves toward the higher potential, the magnetic toner dt on the recording electrode line 2Oa to which a voltage of -2O0V is applied in the recording section W where the interval is the narrowest and the electric field is the largest. Only the black dots are selectively transferred to the surface of the cylindrical electrode 5, forming black dots.

On the other hand, when one bit of recording data is "L", the corresponding driver transistor TR is turned off and the recording electrode line 20 is turned off.
a becomes the ground potential. As a result, the potential difference seen from the cylindrical electrode 5 to its corresponding recording electrode line 20a becomes -30V, and the negative magnetic toner dt remains held on the recording electrode line 2Oa side and does not transfer.

As mentioned above, the corresponding recording electrode line 2 is
The potential of 0a is selectively controlled to the ground potential of 1200V, and a toner recorded image is formed on the surface of the opposing cylindrical electrode 5 in accordance with the recorded data. This toner recorded image is conveyed to the image transfer section T as the cylindrical electrode 5 rotates in the counterclockwise direction a, as shown in FIG. transferred onto paper.

Incidentally, in order to adjust the density of the above-mentioned toner recorded image, it is sufficient to change the bias voltage of the bias power supply 5a. In that case, the appropriate adjustment range is about 0 to -30V, and OV
The closer it is to , the higher the image density.

The magnetic toner dt' remaining in the recording section W without being transferred to the cylindrical electrode 5 side moves downstream with the progress of the traveling wave magnetic field, is scraped off from the surface of the outer covering member 15A by the scraping plate 19, and is removed by the stirring roll. 12 and is stirred and mixed with the stored toner.

Note that the present invention is not limited to the specific embodiments described above (it goes without saying that various modifications can be made within the technical scope of the present invention).

For example, as shown in FIG.
It may be laid over an appropriate length region upstream from the recording portion W on the outer circumferential surface or downstream as shown by the two-dot chain line.

Furthermore, as shown in FIG. 11, the recess 2 can be formed without dividing the base 27.
7a, the drive circuit element 21 may be built in the recess 27a, and the recording electrode sheet 28 may be laid over a wide area from the upstream end of the outer covering member 29 to the recording mW.

Note that in order to prevent dust from entering the recess 27a,
What is necessary is to cover the cover 30 with the lid 30.

〔Effect of the invention〕

As described above in detail, according to the present invention, a traveling wave magnetic field generating means having no rotation mechanism is used as a developer conveying means, and a plurality of recording electrodes are arranged on the developer conveying path at a minute distance from the opposing electrode. By arranging the recording electrodes in parallel with a gap between them and installing the drive circuit for the recording electrodes inside the developer conveying means, a large number of recording electrodes can be arranged in parallel at high density with a simple structure. Therefore, it becomes possible to manufacture a recording device that can form a high-resolution recorded image in a small size and at low cost. In addition, since the developer is transported without using a rotating mechanism and it is a non-contact recording method, the durability of the recording device is improved and it is possible to stably form high-resolution images over a long period of time. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the overall configuration of a recording apparatus as an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a recorded image forming unit and its peripheral configuration in the recording apparatus, and FIG.
Figures (a) and 3(b) are explanatory diagrams showing the configuration of the excitation coil in the recording device, respectively, Figure 4 is a graph diagram showing the waveform of the current flowing through the excitation coil, and Figure 5 is the Graphs showing temporal changes in excitation magnetic field distribution curves due to excitation coils, FIGS. 6 and 7 are explanatory diagrams showing other embodiments of excitation coils, and FIG. 8 shows the above-mentioned recording image forming unit. FIG. 9 is a circuit diagram showing the drive circuit configuration of the recording image forming unit, and FIGS. 10 and 11 are sectional views showing other embodiments of the recording image forming unit, respectively. . 1... Paper feed cassette 3... Standby roll pair 4... Transfer charger 5... Cylindrical electrode 5a... Bias power supply (cylindrical electrode side) 8... Fixing device 10... Paper discharge Tray 11... Unit container 12... Stirring roll 14, 24, 27... Base 14A, 14B... Divided base 15.15A, 15B, 26.29... Outer covering member 16
... Coil portion 16'... Coil 16''... Conductor portion 18... Doctor blade 19... Scraping plate 20, 25, 28... Recording electrode sheet 20a... Recording electrode wire 20b ... Base film 21 ... Drive circuit element 22 ... Input wiring circuit 24 ... Bias power supply (recording electrode side) T ... Image transfer section U ... Recording image forming unit U, ... Recording unit W...recording section

Claims (3)

[Claims] (1) An excitation coil is arranged along the back surface of a developer transport body made of a non-magnetic material that is fixedly laid so that the surface serves as a developer transport path, and currents of multiple phases with different phases are applied to the excitation coil. a developer transporting means for transporting the developer by forming a magnetic field that moves in waves along the surface of the developer transporting member; and a plurality of recording electrodes arranged on the surface of the developer transporting member in a direction perpendicular to the developer transporting direction. and a recording means comprising a drive circuit installed inside the developer conveying means for outputting a recording voltage to each of the recording electrodes according to input recording information, and a recording means disposed facing the recording electrodes with a predetermined gap maintained therebetween. By applying the recording voltage to an electrode facing portion where the recording electrode and the cylindrical electrode face each other, the developer transported by the developer transport means to the electrode facing portion is transferred to the electrode facing portion. An electrostatic recording device characterized by selectively transferring to a cylindrical electrode side. (2) The electrostatic recording device according to claim 1, wherein the developer is a one-component insulating developer containing at least an insulating resin, a magnetic fine powder, and colorant particles. (3) The electrostatic recording device according to claim 1, wherein the developer is a two-component developer in which a magnetic carrier and an insulating toner are mixed in a predetermined ratio.