JPH05116365A - Electrostatic recording apparatus - Google Patents

Abstract

PURPOSE:To inexpensively provide a miniaturized electrostatic recording apparatus capable of stably forming a good recording image free from a residual image or disturbance and enhanced in resolving power over a long period of time without providing an exclusive cleaning member. CONSTITUTION:A recording electrode EL is provided to the recording part W closely opposed to the peripheral surface of the cylindrical electrode 5 provided to the peripheral surface of a developing sleeve 12 and the LSI 15 driving the electrode EL is arranged on the peripheral surface of the developing sleeve 12 on the upstream side in the toner feed direction (e) of the recording part W. The LSI 15 is covered with a cover film 16 and a magnet roll 13 is built in the developing sleeve 12 in a freely rotatable manner. The recording control part C connected to the LSI 15 applies the signal voltage corresponding to recording data to the whole of recording electrode wires containing the recording electrode EL at the time of recording and applies cleaning voltage to the electrode wires at the time of non-recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording apparatus that transfers a developer, which is conveyed along a predetermined path, to a recording medium according to recording information to form a recorded image.

[0002]

2. Description of the Related Art Conventionally, a multi-stylus printer is well known as one of electrostatic recording devices.
This multi-stylus printer forms a recording head by arranging a large number of needle-shaped recording electrodes in the main scanning direction at minute equal intervals, and selectively applies a voltage to each needle-shaped electrode according to a recording signal to print on a sheet. Is directly discharged to form an electrostatic latent image. In this case, special paper coated with a high electric resistance agent is used so that the electric charge can be easily and stably held on the paper. However, such a special paper is not preferable as a paper for office work because it has a poor writing property with a pencil or a pen and has a problem of storability because it deteriorates depending on environmental conditions such as humidity.

If the distance between the tip of the needle-shaped electrode and the surface of the paper is large, the discharge electric field spreads and the dots formed become large, making it difficult to obtain a high-resolution recorded image. For that reason,
A gap material is provided on the paper surface, and the gap material and the tip of the needle-shaped electrode are brought into sliding contact with each other to secure a minute gap. However, according to this method, there is a problem that the tip of the needle-shaped electrode is worn.

Therefore, as a recording method 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, a toner image is formed on a drum-shaped intermediate recording medium, and then the toner is formed. A method of transferring an image onto a sheet is used. In the case of this method, since the intermediate recording medium is repeatedly used, it is necessary to surely perform cleaning every time the intermediate recording medium is used so that an afterimage does not occur. However, if a known mechanical cleaning means is provided around the intermediate recording medium, the electrostatic recording apparatus becomes large.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to use plain paper and to provide a good recorded image having no afterimage and high resolution without providing a dedicated cleaning member. It is an object of the present invention to provide a small-sized and inexpensive electrostatic recording device that can be stably formed over a long period of time.

[0006]

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, a plurality of recording electrodes arranged in parallel on the surface of the developer carrying member at intervals, and arranged to face the recording electrode. An electrode driving means including a counter electrode, an electrode driving circuit element that outputs a driving voltage to each recording electrode, and a connecting member that connects the electrode driving circuit element and each recording electrode, and an output voltage of the electrode driving element are controlled. And a recording control means for forming a recording electric field according to recording information in a recording unit in which the recording electrode and the counter electrode are close to each other, and selectively transfers the conveyed developer to the counter electrode side. In an electrostatic recording device for forming a recorded image, the electrode driving means is laid along the surface of the developer carrying member on the upstream side with respect to the developer conveying direction of the recording section, and the recording control means performs the recording. Do not form an electric field Optionally during non-recording, it is an main point to be output the cleaning voltage to form the cleaning electric field of the recording field in the opposite direction to the connecting member from the electrode driving circuit elements.

[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. 2 is a schematic cross-sectional view showing the overall configuration of the electrostatic recording device as one embodiment of the present invention. In the figure, reference numeral 1 is a paper feed cassette in which plain papers P are stacked and stored, and is detachably attached to the bottom of the machine body. Above the tip of the inserted paper cassette 1,
The paper feed roller 2 is arranged so as to be rotatable in the direction of the arrow.
A standby roll pair 3 is arranged in front of the paper feed roller 2, and after the paper P fed by the paper feed roller 2 is temporarily stopped from advancing to adjust the conveyance posture, the image transfer unit on the downstream side is arranged. The sheet is re-fed so as to be synchronized with the arrival timing of the recorded image described later.

A transfer roll 4 is arranged in a sheet conveying path extending obliquely upward from the pair of standby rolls 3. A cylindrical electrode 5 also serving as an intermediate recording medium and a counter electrode is arranged to face the transfer roll 4. The peripheral surface facing portions of both the cylindrical electrode 5 and the transfer roll 4 become the image transfer portion T.
In the image transfer portion T, the toner recording image formed on the peripheral surface of the cylindrical electrode 5 and conveyed along with its rotation as described later is transferred onto the sheet re-fed by the standby roll pair 3.

In this example, the cylindrical electrode 5 is driven and rotated in the counterclockwise direction indicated by arrow a. A bias power source 5a for applying a bias voltage having the same polarity as the toner charging polarity is connected to the cylindrical electrode 5. In this example, since a two-component developer composed of a toner having a negative (−) triboelectric charging characteristic and a magnetic carrier having a positive (+) triboelectric charging characteristic is used as the developer, the bias power source 5a produces a negative charge. A voltage is applied and the voltage value is set to -50V. The cylindrical electrode 5 of this example is arranged in a recording image forming unit U which is detachably attached to the machine body. The configuration of the recording image forming unit U will be described later in detail.

On the downstream side (obliquely above) of the image transfer section T,
A fixing device 6 is provided. The fixing device 6 of this example comprises a heating roll 6a and a pressure contact roll 6b, and heat-fixes the toner image when the paper is sandwiched between the rolls 6a and 6b and conveyed. The fixed sheet is discharged and stacked on the discharge tray 7 from the discharge port Oe in a face-up state with the image side facing up.

The detailed structure of the recording image forming unit U will be described below. As shown in FIG. 1, the recording image forming unit U generally comprises the above-mentioned cylindrical electrode 5, a toner storage tank 8 for storing the replenishment toner t0, and a development recording tank 9 having a recording means and a developer conveying means. .. The developer is not limited to a two-component developer, and a one-component developer such as a magnetic toner composed of an insulating resin, magnetic fine powder and colorant particles can also be used.

A stirring blade 8a is rotatably arranged in the toner storage tank 8. The stirring blade 8a stirs the stored replenishment toner t0 to prevent aggregation. Further, a toner supply port (not shown) is formed in a partition wall Uw between the toner storage tank 8 and the development recording tank 9, and a toner supply roll 10 is installed in this toner supply port. Toner supply roll 10
Is rotated in accordance with the toner concentration of the developer d circulating in the developing / recording tank 9 to replenish the developing / recording tank 9 with an appropriate amount of replenishment toner t0. As a result, the toner concentration of the developer d in the development recording tank 9 is controlled within the proper range.

At the bottom of the developing and recording tank 9, a stirring roll 11 for stirring the developer d is arranged so as to extend in the horizontal direction. The stirring roll 11 of this example is rotated in the arrow B direction.

A developing sleeve 12 as a developer carrying member is horizontally installed in parallel with the cylindrical electrode 5 above the stirring roll 11 with a minute gap therebetween. The minute gap where the peripheral surfaces of the developing sleeve 12 and the cylindrical electrode 5 closely face each other serves as a recording portion W on which a toner recording image is formed. The developing sleeve 12 is made of a non-magnetic material, and has a magnet roll 1 as a developer conveying means inside.
3 is rotatably built in. Different magnetic poles are alternately magnetized on the circumferential surface of the magnet roll 13, and the magnet roll 13 is driven and rotated in the counterclockwise direction indicated by an arrow C, and the developer d is broken along the circumferential surface of the developing sleeve 12. Carry in the clockwise direction indicated by arrow d.

Then, a recording electrode sheet 14 having recording electrodes and electrode driving means for the recording electrodes is attached and laid in an area upstream of the recording portion W on the peripheral surface of the developing sleeve 12 with respect to the developer conveying direction d. is there. The recording electrode sheet 14 of this example uses a flexible printed circuit board (FPC) made of a non-magnetic material, and as shown in FIG. 3, a plurality of recording electrode lines 14a are arranged in parallel on a base film 14b at a predetermined fine pitch. Is formed to extend. The recording electrode sheet 14 is attached to the recording electrode wire 14a.
Are formed on the peripheral surface of the developing sleeve 12 so that the extending direction and the arranging direction of the developing sleeve are aligned with the peripheral direction and the width direction of the peripheral surface of the developing sleeve 12, respectively. In that case, one end surface of the recording electrode sheet 14 in which the respective tips of the recording electrode wires 14a are lined up is aligned with the position of the peripheral surface of the developing sleeve 12 which is closest to the peripheral surface of the cylindrical electrode 5. By thus providing the recording electrode sheet 14 on the peripheral surface of the developing sleeve 12, the width direction of the peripheral surface of the developing sleeve 12 serving as the developer transport path becomes the main scanning direction,
The number of recording signal lines 14a corresponds to the maximum number of data for one main scanning line. In this example, a large number of recording electrode wires 14
a with a pitch of 84.6 μm (3
The pattern is formed by an etching method at a density of 00 DPI).

A plurality of LSIs 15 as electrode driving circuit elements are mounted on the end portion of the recording electrode sheet 14 opposite to the recording portion W side. These plural LSIs 15 include
An appropriate number of recording electrode wires 14a are divided and connected.
Further, as shown in FIG. 1, each LSI 15 is connected to a recording control section C as recording control means for controlling the entire recording operation of the electrostatic recording apparatus of this example. The recording control unit C is the LSI 1
In addition to sending a print signal corresponding to the print information to 5, the non-printing signal is sent selectively to a non-transfer toner cleaning command, which will be described later.

In FIG. 1, the recording electrode sheet 1 described above is used.
The end portion of the No. 4 LSI 15 is mounted on the flat surface portion 12a formed on the upper peripheral surface of the developing sleeve 12.
By forming the flat portion 12a on the peripheral surface of the developing sleeve 12 in this manner, the LSI 15 can be easily installed. Then, the cover film 16 made of a non-magnetic material is formed in the area of the recording electrode sheet 14 excluding the tip portion extending to the recording portion W.
Is formed to have substantially the same curvature as the peripheral surface of the developing sleeve 12 and is covered therewith. As a result, the surface of the cover film 16 serves as a developer transport path, and the LSI 15 can be prevented from being damaged by friction with the developer or the like. Further, since the cover film 15 is bent and installed in an arc shape, the developer can be smoothly moved along the surface thereof. Instead of covering with the cover film 15, the surface of the recording electrode sheet 14 may be coated with a non-magnetic material. When the protective member such as the cover film 16 is covered in this manner, the tip of the recording electrode wire 14a which does not cover the protective member becomes the recording electrode EL which is substantially involved in the recording image formation. Therefore,
The portion of the recording electrode wire 14a excluding the tip portion that becomes the recording electrode EL serves as a connecting member that constitutes the electrode driving circuit element and the electrode driving means. This connecting member portion serves as a cleaning member that cleans untransferred toner as described later.
The area where the recording electrode EL faces the circumferential surface of the cylindrical electrode 5 is the recording portion W described above.

By installing the recording electrode and the electrode driving means for the recording electrode as described above, the portion of the connecting member for connecting the recording electrode and the electrode driving circuit element can be shortened. That is,
Recording electrode line 14a connecting the recording electrode EL and the LSI 15
But it's short. This not only makes the recording electrode sheet 14 small and inexpensive, but also reduces the so-called antenna effect of the recording electrode wire 14a, making it less susceptible to noise. As a result, it is possible to stably form a recorded image that accurately corresponds to the recorded information.

A doctor blade 17 for regulating the layer thickness of the developer d to an appropriate thickness is provided near the peripheral surface of the developing sleeve 12 and substantially opposite to the recording portion W. The doctor blade 17 of this example is configured such that a part of the surface of the partition wall Uw on the side of the developing / recording tank 9 is projected until it is close to the peripheral surface of the developing sleeve 12 with a minute gap D therebetween.

A step G is formed immediately downstream of the recording electrode EL in the recording section W. By providing this step G, the toner transferred to the peripheral surface of the cylindrical electrode 5 to form a recorded image and the developer remaining on the surface of the developing sleeve 12 are sufficiently separated from each other after the image is formed, and both interfere with each other. It is possible to reliably prevent the inconvenience of disturbing the formed image.

Recording portion W on the peripheral surface of the developing sleeve 12
The developer wraparound prevention member 1 is provided on the lower peripheral surface on the downstream side.
8 are provided. The wraparound prevention member 18 prevents the returned residual developer from being returned directly to the upstream side of the doctor blade 17 along the peripheral surface of the developing sleeve 12 without passing through the stirring roll 11.

Next, a recording image forming operation in the electrostatic recording apparatus of this example will be described. In FIG. 1, when the magnet roll 13 is driven and rotated in the direction of arrow C, a rotating magnetic field for rotating the magnetic particles in the developer d is formed on the peripheral surface of the developing sleeve 12, and the developer d forms a brush. Meanwhile, the magnet roll 13 is conveyed in the direction of the arrow D, which is opposite to the direction of rotation. The conveyed developer d reaches the recording portion W after being regulated by the doctor blade 17 to have a predetermined thickness. At this time, the toner particles are sufficiently negatively charged by friction with the carrier particles, the peripheral surface of the developing sleeve 12 or the surface of the cover film 16.

The recording control unit C controls the LS according to the input recording information.
The LSI 15 which sends a recording signal to I15 and receives this signal,
A signal voltage corresponding to a recording signal is applied to each recording electrode EL. As a result, in the recording portion W, a recording electric field corresponding to the recording signal is formed between the recording electrode EL and the surface of the cylindrical electrode 5, and the toner in the developer d is selectively transferred to the surface of the cylindrical electrode 5. In this case, in this example, when the recording signal corresponding to 1 bit is "H", the corresponding recording electrode EL is -2.
A signal voltage of 00V is applied. At this time, a voltage of -50 V is applied to the cylindrical electrode 5 by the bias power source 5a as described above, so that the corresponding recording electrode E is transferred from the cylindrical electrode 5 to the corresponding recording electrode E.
A recording electric field based on the potential difference of 150 V is formed toward L. Since the negatively charged toner particles move to the higher potential side, only the toner particles on the recording electrode EL to which a signal voltage of −200 V is applied (recording signal is “H”) selectively travels around the cylindrical electrode 5 times. It transfers to the surface and forms one black dot.

On the other hand, when the 1-bit recording signal is "L", the LSI 15 switches the signal voltage to the corresponding recording electrode EL to the ground potential. As a result, the potential difference seen from the cylindrical electrode 5 to the corresponding recording electrode EL is −50 V,
Since the direction of the lines of electric force (direction of the electric field) is opposite to that in the case of "H" described above, the toner particles negatively charged are retained on the recording electrode EL and do not transfer.

As described above, L as the electrode drive circuit element is used.
By SI15, the potential of the recording electrode EL is selectively switched between -200 V and the ground potential according to the recording signal corresponding to the input recording information, and a toner recording image corresponding to the recording information is formed on the surface of the cylindrical electrode 5 around. At this time, as described above, the recording electrode line 14a connecting the recording electrode EL and the LSI 15 is connected.
Therefore, the toner recording image accurately corresponding to the recording information can be stably formed without the noise mixed in the recording signal. The density of the toner recording image can be adjusted by changing the bias voltage of the bias power source 5a. A suitable adjustment range in that case is about 0 to -50V, and
The image density increases as it approaches V.

In FIG. 2, the toner recording image formed on the peripheral 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 set by the standby roll pair 3 here. It is transferred onto the paper that is measured and re-fed. The untransferred toner that has not been transferred and remains on the peripheral surface of the cylindrical electrode 5 is returned to the recording portion W again as the cylindrical electrode 5 rotates. The untransferred toner remaining on the peripheral surface of the cylindrical electrode 5 is cleaned and removed as follows.

In FIG. 1, the recording control section C sends a cleaning signal to the LSI 15 in anticipation of a non-recording time such as a time corresponding to a paper-to-paper transportation interval, and the LSI 15 receiving the cleaning signal receives the recording electrode wire 14a. (See FIG. 3) A cleaning voltage is applied to the entire surface. In this case, the cleaning voltage needs to form an electric field capable of transferring the untransferred toner remaining on the peripheral surface of the cylindrical electrode 5 to the recording electrode sheet 14 side, that is, an electric field in a direction opposite to the recording electric field described above. Therefore, the potential is set higher than the bias voltage applied to the cylindrical electrode 5. That is, in this example, since the bias voltage of the cylindrical electrode 5 is set to -50V, the cleaning voltage is set to + 50V, for example. As a result, the potential difference seen from the cylindrical electrode 5 to the recording electrode wire is −
The electric field becomes 100 V, and the cleaning electric field based on this potential difference causes an area where the recording electrode wire and the circumferential surface of the cylindrical electrode 5 face each other, that is, the connecting member portion of the recording electrode wire and the circumferential surface of the cylindrical electrode 5 face upstream from the recording portion W. It is formed over a region (hereinafter, referred to as a cleaning region) to be formed. This cleaning electric field has the same direction of electric lines of force as the electric field (corresponding to the white dot) based on the potential difference of −50 V formed corresponding to the above-mentioned “L” recording signal, and its magnitude is larger than that. Due to this cleaning electric field, the negatively charged untransferred toner remaining on the peripheral surface of the cylindrical electrode 5 is recorded.
And the peripheral surface of the cylindrical electrode 5 is cleaned. Further, in the cleaning area on the upstream side of the recording section W, the developer carrying path is suddenly narrowed, so that the carried developer d is temporarily retained to form a toner pool. The untransferred toner is also removed from the peripheral surface of the cylindrical electrode 5 by the scraping effect of the toner chain grown in the toner pool. In this way, after the untransferred toner is removed from the peripheral surface of the cylindrical electrode 5 by cleaning, the recording operation is performed again in the recording unit, so that there is no image defect such as an afterimage due to defective cleaning and a high-resolution recorded image is stable. Formed in. Further, since the entire recording means constituted by the recording electrode EL, the LSI 15 as the electrode driving means for the electrode, and the recording electrode wire 14a connecting them is provided on the upstream side from the recording portion W, it is possible to change from recording to non-recording. There is no possibility that the formed recording image is disturbed by the cleaning electric field.

In FIG. 1, the developer that has not transferred to the surface of the cylindrical electrode 5 and remains on the recording electrode sheet 17 side has a step G formed immediately downstream of the recording portion W, so immediately after passing through the recording portion W. Move away from the surface of the cylindrical electrode 5. Therefore, it is possible to surely avoid the disadvantage that the toner recording image formed on the surface of the cylindrical electrode 5 in the recording portion W is disturbed by mutual interference with the residual developer on the surface of the developing sleeve 12.

The residual developer not transferred to the cylindrical electrode 5 side in the recording section W but conveyed to the downstream side is scraped off from the surface of the developing sleeve 12 by the wraparound prevention member 18, and is developed and recorded.
It drops to the bottom and is returned to the doctor blade upstream side of the peripheral surface of the developing sleeve 12 as the stirring roll 11 rotates. At this time, the toner is uniformly stirred with the replenishment toner t0.

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

For example, as means for conveying the developer,
Not limited to the magnet roll, a conveying means that uses a traveling wave magnetic field generated by an exciting coil may be used. Further, although the developer containing the toner of negative (−) chargeability was used as the developer, it is also possible to use the developer containing the toner of positive (+) chargeability. In that case, the polarities of the voltages applied to the recording electrode and the counter electrode may be positive (+).

[0032]

As described above in detail, according to the present invention, a plurality of recording electrodes are installed in parallel in the developer transporting route for transporting the developer along a predetermined route and a minute gap is maintained. Electrode driving means is provided which is provided with opposing electrodes, and which has electrode driving circuit elements for driving the recording electrodes and a connecting member for connecting the electrodes along the developer transport path on the upstream side of the recording section where the electrodes face each other. The recording control means selectively outputs a cleaning voltage capable of removing untransferred toner remaining on the counter electrode from the electrode driving circuit element during non-recording to form a cleaning electric field in a region where the connection member and the counter electrode face each other. As a result, it is possible to accurately and stably secure a minute gap in the recording portion necessary for forming a high-resolution image, and to carry a toner recording image without providing a dedicated cleaning unit. Untransferred developer can be reliably cleaned removed from counter electrode surface. Then, since the untransferred developer is cleaned in the area where the connection member on the upstream side of the recording portion and the counter electrode face each other, it is possible to reliably form a recorded image without an afterimage in the recording portion, and the formed recording image is recorded on the downstream side of the recording portion. Thus, it is possible to avoid the inconvenience caused by applying the cleaning voltage. Further, since the electrode driving means is laid along the developer transport path, the connection member can be short and inexpensive, and it is possible to prevent the disadvantage that the recording operation is disturbed by noise due to the antenna effect of the connection member. ..
Therefore, it is possible to reduce the size of the electrostatic recording apparatus that is capable of stably forming a high-resolution recorded image that accurately corresponds to the recorded information without image defects such as an afterimage and disorder due to poor cleaning. Can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a recording image forming unit and its peripheral configuration in an electrostatic recording apparatus as an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the overall configuration of the electrostatic recording device.

FIG. 3 is a partially cutaway perspective view showing the recording image forming unit.

[Explanation of symbols]

 5 Cylindrical Electrode 5a Bias Power Supply (for Cylindrical Electrode) 8 Toner Storage Tank 9 Development Recording Tank 10 Toner Replenishing Roll 11 Auger Roll 12 Developing Sleeve 13 Magnet Roll 14 Recording Electrode Sheet 14a Recording Electrode Wire 15 LSI 16 Cover Film 17 Doctor Blade 18 Surrounding Preventing member 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 the developer along the surface of the developer carrying member, and a gap on the surface of the developer carrying member. A plurality of recording electrodes arranged in parallel with each other, a counter electrode arranged to face the recording electrodes, an electrode drive circuit element that outputs a drive voltage to each recording electrode, and the electrode drive circuit element and each recording electrode are connected. And a recording control unit that controls the output voltage of the electrode driving element, and a recording electric field is formed in a recording unit in which the recording electrode and the counter electrode are close to each other according to recording information. In the electrostatic recording apparatus that selectively transfers the transported developer to the counter electrode side to form a recorded image, the electrode driving means is provided on the upstream side with respect to the developer transport direction of the recording unit. Surface of developer carrying member The recording control means selectively outputs a cleaning voltage for forming a cleaning electric field in a direction opposite to the recording electric field from the electrode drive circuit element to the connecting member when the recording control means does not form the recording electric field. An electrostatic recording device characterized by: