JPH04333068A - Image recorder - Google Patents

Abstract

PURPOSE:To obtain an image of high quality without any reduction in density even in continuous recording by forcedly feeding toner to a space formed between a recording electrode and a recording member from a recessed or projecting parts on outer periphery of a sleeve. CONSTITUTION:A rotatable hollow sleeve 13 of a non magnetic body provided with a multiple number of recessed or projecting parts on its outer periphery is provided in a hopper 6 on upstream side of recording direction with respect to the recording electrode 5 to feed toner 23 to tip of the recording electrode 5 installed in the vicinity of the recording member 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for forming toner images using magnetic toner, such as conductive magnetic toner (hereinafter abbreviated as "toner").

0002

[Prior Art] Conventionally, a cylindrical recording member and a recording electrode consisting of a plurality of recording electrode needles are arranged on the member at a small distance, and an area (recording area) constituted by the recording member and the tip of the recording electrode. Conductive magnetic toner is supplied to the recording electrode, and the toner is aligned between the recording electrode needle and the recording member to form a conductive path by the magnetic field of a magnetic field generating means disposed downstream of the recording electrode in the recording direction, and an image is formed on the recording electrode needle. 2. Description of the Related Art An image recording apparatus is known that forms a toner image by applying a recording voltage according to a signal. Such an image recording apparatus is described in, for example, Japanese Patent Laid-Open No. 2-173766.

0003

[Problems to be Solved by the Invention] In the above-mentioned prior art, a toner supply source and a magnetic field generation means are provided in the path for conveying the conductive magnetic toner to the recording electrode, but the arrangement of the toner supply source and the magnetic field generation means is In some cases, the magnetic force acting on the toner from the magnetic field generating means makes it difficult to convey the toner to the tip of the recording electrode, resulting in a decrease in density during continuous recording.

An object of the present invention is to provide an image recording apparatus having a small toner supply section that supplies a sufficient amount of toner to the gap formed between a recording electrode and a recording member, and that provides high image quality and does not cause a decrease in density during continuous recording. Our goal is to provide the following.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a column-shaped recording electrode in which a plurality of electrode needles are arranged perpendicularly to the moving direction of a recording member, and a micro gap between the recording electrode and the recording member. The recording member is provided and moves; a hopper for depositing magnetic toner on the upstream side of the recording electrode in the moving direction; and a sleeve having a built-in magnetic field generating means in the hopper and having a plurality of concave or convex portions on the outer periphery. a drive circuit that applies a voltage corresponding to an image to be recorded to the recording electrode to charge the toner portion in contact with the recording member; and a drive circuit that applies a magnetic field to the minute gap on the downstream side of the recording electrode in the moving direction and a second magnetic field generating means for supplying the magnetic field.

[0006]

[Operation] The toner is attracted to the sleeve by the static magnetic field of the magnetic field generating means in the hopper, and due to the inertial force caused by the rotation of the sleeve and the pushing force due to the concave or convex portions on the outer circumference of the sleeve, the toner is relatively irregular compared to the recording density. A sufficient amount of toner is conveyed to the recording member side, and the toner is aligned in the gap formed between the recording member and the recording electrode by the action of a magnetic field.

[0007] This prevents the amount of toner in the recording electrode portion from becoming insufficient due to changes in the amount of accumulated toner due to toner consumption or the influence of the magnetic force exerted on the toner by the static magnetic field of the magnetic field generating means, so that toner is always supplied to the recording area. The supply amount is sufficient, and high quality images with no decrease in density can be obtained even during continuous recording.

[0008]

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a cross-sectional side view of an image recording apparatus according to the present invention.

The configuration of the embodiment will be explained below. Inside the hopper 6 is conductive magnetic toner (hereinafter abbreviated as toner).
23 is accumulated and stored, and the toner at the bottom is in contact with the recording member 1.

[0011] The sleeve 13 has a diameter of about 14 m, for example.
The recording member 1 is made of a hollow non-magnetic material and is rotatably supported within the hopper 6, and is rotated by a drive mechanism (not shown) in the direction of the arrow c in the figure at a circumferential speed approximately equal to the circumferential speed of the recording member 1. Eight grooves are provided on the outer periphery of the sleeve 13 at intervals of about 5.5 mm, and the depth of the depressions is about 0.5 mm.

The magnetic field generating means 12 is a permanent magnet fixed to the main body of the recording apparatus within the sleeve 13, and is, for example, a ferrite magnet YBM- manufactured by Hitachi Metals, Ltd. with a saturation magnetic flux density of approximately 0.4 T (4,000 Gauss). It is 2BD.

The recording electrodes 5 include an electrode substrate 5a made of a non-magnetic insulator, and arranged in a row on the electrode substrate 5a in an out-of-plane direction in the figure.
For example, recording electrode needles 5e made of conductors arranged in a row at a pitch of 125 μm, an integrated circuit 5d arranged on the electrode substrate 5a and applying a recording voltage to the recording electrode needles 5e in accordance with an image signal, and protecting the integrated circuit 5d. The heat sink 5b is composed of a protective member 5c made of an insulating non-magnetic material, and a heat sink 5b made of a non-magnetic material with good thermoelectric properties and fixed to the electrode substrate 5a.

The drum-shaped recording member 1 has a base, for example,
A non-magnetic conductor 1a made of an aluminum alloy or the like, the surface of which is formed of an insulator 1b made of, for example, an anodic film of aluminum or a coating film of a thermosetting resin, and a recording electrode needle 5c.
and a gap of approximately 20 to 300 μm.

The recording member 1 is rotated by a drive mechanism (not shown) in the direction of arrow b shown in the figure, which is perpendicular to the column direction of the recording electrode needles 5e.

The endless belt 3 is located on the downstream side of the recording electrode 5 in the recording direction and close to the recording electrode 5, and is run by a belt guide 20 made of a non-magnetic material and fixed to the drive roller 18 and the main body of the apparatus. It runs in the direction of the arrow a shown in the figure by a drive roller 18 which is supported by a drive roller 18 and rotated by a drive mechanism (not shown).

The second magnetic field generating means 11 includes an endless belt 3
A permanent magnet is fixed to the main body of the recording device within the casing, for example, a ferrite magnet YBM-2BD manufactured by Hitachi Metals, Ltd. with a saturation magnetic flux density of about 0.4 T, which supplies magnetic flux to the recording electrode needle 5e and the hopper 6. The magnetic field generating means 12 is provided with the same magnetic poles facing each other.

On the downstream side in the recording direction of the second magnetic field generating means 11, a magnetic field generating means 11 is located close to the recording member 1, is fixed to the recording apparatus main body within the endless belt 3, and has a plurality of magnetic poles in the rotating direction of the recording member 1. A non-image detoning magnet 21 is arranged. The non-image toner removal magnet 21 is a permanent magnet, for example, a ferrite magnet YBM-2BD manufactured by Hitachi Metals, Ltd. with a saturation magnetic flux density of about 0.4 T, and has a plurality of magnetic poles on the side facing the recording member 1. A magnetic field is supplied onto the recording member 1.

The toner conveying magnet 24 is fixed on the belt guide 20 along the inner circumference of the endless belt 3 from the downstream side in the recording direction of the non-image toner removing magnet 21 to near the drive roller 18. The toner conveying magnet 24 has a plurality of magnetic poles perpendicular to the running direction of the endless belt 3, and supplies magnetic flux onto the endless belt 3.

The scraper 8 has one side in contact with the endless belt 3, and the other side is fixed to the top of the recording electrode 5 by means not shown.

The rotating blade 7 is rotated in the direction of arrow e by a drive mechanism (not shown).

A transfer roller 4 that presses the recording paper 2 against the recording member 1, a cleaning blade 15 made of a flexible member that contacts the recording member 1 on one side, and a cleaning blade 15 supported on the outer periphery of the recording member 1. A support body 14 is provided.

A blade 16 is installed in the discharged toner receiver 17 and is rotated by a drive mechanism (not shown).

A charge eliminating blade 9 is disposed downstream of the cleaning blade 15 in the recording direction with one side in contact with the recording member 1. The static eliminating blade support 10 is arranged such that the static eliminating blade 9 always contacts the recording member 1 on one side with a constant pressure in the direction in which the recording electrode needles 5e are arranged.

In this embodiment, the recording electrode needle 5e has a diameter of 125 μm.
Since they are arranged at a pitch, recording can be performed at a high recording density of 8 dots per 1 mm.

Toner 23 deposited in toner hopper 6
are attracted by the magnetic field generating means 12 onto the grooved sleeve 13 provided at sufficiently large intervals compared to the recording density. The sucked toner 23 is conveyed to the tip of the recording electrode by a grooved sleeve 13 that rotates in the direction of arrow c in the figure, and is deposited on the recording member 1. Therefore, regardless of the amount of toner 23 in the hopper 6, a sufficient amount of toner 23 can always be supplied to the tip of the recording electrode 5, so that changes in the amount of toner 23 deposited in the hopper 6 due to toner consumption or There is no influence of variations in the amount of toner deposited in the hopper 6 in the arrangement direction of the recording electrode needles 5b, and the amount of toner 23 supplied to the tip of the recording electrode 5 is sufficient, resulting in high image quality. The toner conveying force generated by the rotation of the recording member 1 and the magnetic attraction force generated by the second magnetic field generating means 11 stably move the toner 23 in the recording direction from the gap between the recording electrode 5 and the recording member 1. Let it flow.

At this time, the driving integrated circuit 5d applies a recording voltage according to the image signal to the plurality of recording electrode needles 5e, selectively charges the toner 23 existing in the gap, and charges are injected. Electrostatic attraction is generated in the charged toner, which adheres to the recording member 1 and becomes image forming toner 23a.

When the non-image toner to which no charge is injected passes through the gap by two forces, the toner transport force and the magnetic attraction force, the magnetic attraction force that overcomes the gravitational field from the second magnetic field generating means 11 causes the non-image toner to move in the direction of the arrow g. It flies toward the second magnetic field generating means 11 as shown in FIG. Second magnetic field generating means 11
The non-image toner remaining on the recording member 1 after overcoming the magnetic attraction from The non-image toner is completely removed from the recording member 1 by minute vibrations caused by the magnetic field, and the non-image toner is removed by the non-image toner removing magnet 2.
Fly towards 1.

The flying non-image toner 23b is attracted onto the endless belt 3 by the magnetic force of the second magnetic field generating means 11 and the magnetic force of the non-image toner removing magnet 21, and as the endless belt 3 runs, it moves in the direction of arrow a. It is conveyed in the direction of , moved onto the scraper 8 by the scraper 8 , and collected into the hopper 6 . The toner transport magnet 24 carries the non-image toner 23
b is held on the endless belt 3 by magnetic force, and the non-image toner 23 is
prevent from falling. The rotary blade 7 rotates in the direction of arrow e to urge the non-image toner 23b to be conveyed onto the scraper 8.

The charged toner 23a forming the image is transferred onto the recording paper 2 by the pressing force of the transfer roller 4 to form an image.

The non-transferred toner 23c remaining on the recording member 1 without being transferred is removed from the recording member 1 by the cleaning blade 15, falls to the end of the discharged toner receiver 17 due to gravity, and is further removed by the screw 16. Due to the rotation, the toner is deposited inside the discharged toner receiver 17.

The charge eliminating blade 9, which is disposed on the downstream side of the cleaning blade 15 in the recording direction with one side in contact with the recording member 1, receives charges from the charged toner 23a forming the image, and the charged toner 23a forming the image is transferred. After that, the residual potential is removed from the dielectric layer 1a of the recording member 1, which still has a residual potential, and the image toner 23a is removed from the static elimination blade support 10. It is placed so that it is in contact with the

FIG. 2 shows calculation results of the magnetic force distribution inside the hopper 6 by the magnetic field generating means 12 and the second magnetic field generating means 11 of the embodiment shown in FIG. The circles in the figure indicate calculation points every 1 mm on the top, bottom, left and right, and the direction of the line segment extending from there indicates the direction of the magnetic force, and the length of the line segment indicates its size. Each step in diameter increases four times in size.

[0034] Here, the magnetic force is expressed as the force exerted by a magnetic field on toner particles when the toner particles exist in space, with gravitational acceleration being 1G. The toner used in the calculation has a magnetization of 50 emu/g, and when the toner magnetization is larger than this value, the magnetic force increases, and when it is smaller, the magnetic force decreases.

In FIG. 2, the recording electrode 5 and the sleeve 13
The direction of the magnetic force in the region 22 in between is directed from the recording member 1 toward the recording electrode 5. That is, toner 23
The direction is opposite to the direction in which the recording electrode 5 is transported to the tip of the recording electrode 5.

In this embodiment, which has a groove on the sleeve 13,
The following advantages of the image recording device of the present invention are shown.

FIG. 3 shows the toner 2 in the hopper 6 of this embodiment.
3 is a diagram illustrating the conveyance state of No. 3. The toner 23 is attracted onto the sleeve 13 by the magnetic field generating means 12 provided within the sleeve 13 . Since a plurality of grooves are provided on the outer periphery of the sleeve 13, the surface area of the outer periphery of the sleeve 13 is increased, and a large amount of toner 23 can be conveyed between the recording electrode 5 and the sleeve 13. Further, by providing the groove, when the sleeve 13 is rotated in the direction C in the figure, the force f pushing the toner is added to the inertial force Fs, which becomes larger than the magnetic force Fm between the recording electrode 5 and the sleeve 13. It becomes easier to convey a regular but sufficient amount of toner 23 to the tip of the recording electrode 5.

FIG. 4 illustrates the state of toner conveyance in a conventional device. The toner 23 is attracted onto the sleeve 13 by the magnetic field generating means 12 provided within the sleeve 13 . When the sleeve 13 is rotated in the direction C, the toner 23 is conveyed to the tip of the recording electrode 5 only by the inertial force Fs. However, as described above, since the magnetic force Fm acts on the region 25 between the recording electrode 5 and the sleeve 13, the toner 23 is blocked in the region 25 and is difficult to be conveyed to the tip of the recording electrode 5.

FIG. 5 shows the results of collecting all-black developed images and measuring the optical density, and shows the optical density versus the all-black recording length. The solid line is based on this example,
This is the result when eight grooves were provided on the outer circumference of the sleeve to convey toner and record. The broken line shows the result when toner was conveyed and recorded without providing a groove on the outer periphery of the sleeve. In the case of a sleeve without a groove, the black density decreases as the total black recording length increases, whereas in the case of a grooved sleeve, a constant black density is maintained regardless of the total black recording length. There is.

FIG. 6 illustrates the toner conveyance state in a second embodiment of the present invention. The difference from the embodiment shown in FIG. 1 is that about 5.5
Eight protrusions with a height of approximately 1 mm were provided at intervals of 1 mm. The toner 23a, which is held up between the recording electrode 5 and the sleeve 13 by magnetic force, is pushed into the tip of the recording electrode 5 by the inertia force generated when the sleeve 13 is rotated and by the protrusion of the sleeve 13, albeit irregularly. A sufficient amount of toner 23 can be transported. Therefore, even during continuous recording, good images can be obtained without a decrease in density.

In the present invention, any shape may be used as long as a concave or convex portion is provided on the outer periphery of the sleeve. Further, according to experiments, even when four concave or convex portions were provided on the outer periphery of a sleeve having a diameter of 14 mm at intervals of about 11 mm, good images were obtained without a decrease in density during continuous recording.

[0042]

According to the present invention, a sleeve having a plurality of concave or convex portions on the outer periphery and containing a built-in magnetic field generating means is provided in the hopper on which conductive toner is deposited, so that the toner in the hopper can generate a magnetic field. The toner is attracted onto the sleeve by the static magnetic field formed by the means, and is not affected by variations in the amount of toner deposited in the hopper or the magnetic force acting on the toner by the magnetic field generating means due to the inertial force and toner pushing force caused by the rotation of the sleeve. Since a sufficient amount of toner can be conveyed to the gap formed between the recording member and the recording electrode, there is no decrease in density even during continuous recording, and a high-quality toner image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the magnetic force distribution of the embodiment shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a toner conveyance state in the embodiment shown in FIG. 1;

FIG. 4 is an explanatory diagram showing a state of toner conveyance in a conventional device.

FIG. 5 is an explanatory diagram comparing the developing performance of the embodiment shown in FIG. 1 and the conventional apparatus shown in FIG. 4;

FIG. 6 is an explanatory diagram showing a toner conveyance state according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Recording member, 2... Recording paper, 3... Endless belt, 4... Transfer roller, 5... Recording electrode, 6... Hopper, 9... Static elimination blade, 11... Second magnetic field generating means, 12... Magnetic field generating means, 1
3... Sleeve, 23... Conductive magnetic toner.

Claims (1)

[Claims] 1. A recording electrode in which a plurality of recording electrode needles are arranged in a row, a cylindrical or cylindrical recording member that rotates with a minute gap between the recording electrode, and the recording member of the recording electrode. a rotatable non-magnetic hollow sleeve having a built-in magnetic field generating means for supplying conductive magnetic toner and provided on the upstream side of the recording electrode; a magnetic field generating means that is provided in the arrangement direction and generates a static magnetic field, applies a recording voltage to the plurality of recording electrode needles according to an image signal, and the recording member passes through the gap by rotation of the recording member. An image recording apparatus for selectively applying electric charge to conductive magnetic toner to obtain a microscopic image of the charged toner, characterized in that a plurality of concave or convex shaped portions are provided on the outer periphery of the sleeve.