JPH0948151A - Image forming device - Google Patents

Abstract

(57) Abstract: An image forming apparatus having high resolution and easy to manufacture. A plurality of apertures 6 are formed side by side on an insulating sheet 2 of an aperture electrode body 1, and a plurality of control electrodes 4 are formed corresponding to each aperture 6. Further, a pair of deflection electrodes 3 are arranged on both the left and right ends of the insulating sheet 2. Then, when the control voltage is applied to the control electrode 4 and the toner is ejected from the aperture 6, the deflection voltage is applied to the deflection electrode 3 to bend the toner in either of the left and right directions so that the toner flies so that the aperture 6 appears. Pixels with doubled resolution in the lined up direction are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which can be used for a copying machine, a printer, a plotter, a facsimile, and the like.

[0002]

2. Description of the Related Art Conventionally, as one of image forming apparatuses, an electrode having a plurality of openings (hereinafter referred to as apertures) is used, and a voltage is applied to the electrode based on image data. U.S. Pat. No. 3,689,935 discloses controlling toner particles so that they can pass through the aperture and forming an image on a support by the toner particles that have passed.

This image forming apparatus comprises a flat plate made of an insulating material, a continuous reference electrode formed on one surface of the flat plate, and a plurality of control electrodes insulated from each other formed on the other surface. , An aperture electrode body having at least one row of apertures formed through each of the control electrodes, and a means for selectively applying a potential between the reference electrode and the control electrode. A means for supplying charged toner particles so that the flow of toner particles passing through the aperture is modulated by an electric potential, and a means for positioning the support in the particle flow path so that the support and the aperture electrode body can move relative to each other. It consists of and.

Also, for example, US Pat. No. 4,743,926.
Nos. 4,755,837, 4,780,733, and 4,847,796 disclose an image forming apparatus in which an aperture electrode body is arranged with a control electrode on the support side and a reference electrode on the toner supply side. There is.

In contrast, US Pat. No. 4,912,489
In the specification of the above U.S. Pat. No. 5,967,967, the voltage applied to the control electrode when the aperture electrode body is off is disclosed by disposing the aperture electrode body with the reference electrode on the support side and the control electrode on the toner supply side. It is described that it can be suppressed to about 1/4 as compared with the image forming apparatus.

[0006] Here, the off-time means the time when the toner particles are not adhered to the support, that is, the time when a blank portion of the image is formed. At the time when a toner image is formed.

[0007]

However, in the conventional image forming apparatus as described above, the voltage is independently applied to the control electrode corresponding to each aperture. For this reason, if an attempt is made to develop a head capable of printing with a higher resolution, there is a problem in that the gap between the apertures becomes narrow, the structure becomes complicated, and its production becomes difficult.

Further, in the conventional image forming apparatus, a large number of apertures and control electrodes and driving elements are required to increase the resolution, which causes a problem of high cost.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus having a simple structure and a high resolution.

[0010]

To achieve this object, in an image forming apparatus according to a first aspect of the present invention, a plurality of charged particle passage portions through which charged particles pass are formed side by side in at least one row. And an electrode array having control electrodes corresponding to each of the plurality of charged particle passage portions, and charged particle supply means for supplying the charged particles to the charged particle passage portion of the electrode array, and the charged particles of the electrode array. In an image recording apparatus configured to record an image by adhering charged particles that have passed through the passing portion to a recording medium, the charged particles that have passed through the charged particle passing portion of the electrode array are aligned with the direction in which the charged particle passing portions are arranged. An electric field generating means for generating a deflection electric field for deflecting in substantially the same direction and a control means for controlling the direction of the deflection electric field generated by the electric field generating means are provided. Therefore, the charged particles that have passed through the charged particle passage portion fly while being bent by the deflection electric field.

Further, in the image forming apparatus according to the present invention, the control means switches the direction of the deflection electric field at a predetermined timing and controls the control voltage applied to the control electrode in accordance with the switching timing to charge. The charged particles are bent and fly in a direction substantially the same as the direction in which the particle passage portions are lined up.

The image forming apparatus according to claim 3 is
The direction of the deflection electric field is switched a plurality of times during the formation of one pixel.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of an image forming apparatus according to the present embodiment. A cylindrical rear electrode roller having a gap of 1 mm on the upper side of an aperture electrode body 1 as an electrode array. A recording medium 2 such as a paper sheet 22 is rotatably arranged on a chassis (not shown) and is inserted into the gap.
It is configured to be able to carry 0. Further, a toner supply device 10 as a charged particle supply means is arranged below the aperture electrode body 1 along the longitudinal direction of the aperture electrode body 1, and further, the back electrode roller 22 is provided. A fixing device 26 is provided at the destination of the recording medium 20 conveyed by the fixing device 26.

Next, the respective constituent elements will be described in detail. The toner supply device 10 includes a toner case 11 which also serves as a housing of the entire apparatus, and a toner 16 which is stored in the toner case 11 as charged particles. It comprises a supply roller 12, a toner carrying roller 14, and a toner layer regulating blade 18. Here, the toner carrying roller 14 carries the toner 16 and conveys it toward the aperture electrode body 1, and the supply roller 12 supplies the toner 16 to the toner carrying roller 14.

The supply roller 12 and the toner carrying roller 14 are rotatably supported by the toner case 11 in the direction of the arrow shown in FIG. Further, the toner layer regulating blade 18
Is for adjusting the amount of the toner 16 carried on the toner carrying roller 14 to be uniform on the roller surface and for uniformly charging the toner 16, and is pressed against the toner carrying roller 14. .

As shown in FIG. 2, the aperture electrode body 1 has 90 μm on a 25 μm thick insulating sheet 2 made of polyimide.
A plurality of apertures 6 each serving as a charged particle passage portion having a square shape of m × 40 μm are formed side by side, and a control electrode 4 having a thickness of 8 μm is arranged along the short side of the aperture. Each control electrode 4 has a conducting wire routed in the direction opposite to the toner supply direction, and is connected to each drive element 9 of the control voltage application circuit 8. And the control electrode 4
Is configured such that −30V or + 30V is applied via the drive element 9. Here, the aperture 6 is not necessarily limited to a quadrangle as shown in FIG. 2, and may be, for example, a circle having a diameter of 60 μm, or may have an oval shape, a triangle shape, a parallelogram shape, or the like.

Further, a pair of deflection electrodes 3 are arranged on both ends of the insulating sheet 2. The deflection electrode 3 is connected to the deflection voltage application circuit 40 and applies a deflection electric field to the toner 16 that has jumped out of the aperture 6 to bend the flight direction of the toner 16 in the left-right direction (the direction in which the apertures 6 are arranged).
V is configured to be switched and applied at a predetermined timing. Therefore, the deflection electrode 3 and the deflection voltage applying circuit 40 form an electric field generating means.

A CPU 42 as a control means is connected to the control voltage applying circuit 8 and the deflection voltage applying circuit 40, and the CPU 42 is configured to operate according to a flow chart described later. The CPU 42 is connected to a feeding device 44 including the back electrode roller 22 and the like for conveying the recording medium 20.

Further, a DC power source 24 is connected between the back electrode roller 22 and the toner carrying roller 14, and this DC power source is + with respect to the back electrode roller 22.
A voltage of 1 kV can be applied.

As shown in FIG. 1, the aperture electrode body 1 has a control electrode 4 and a deflection electrode 3 on the recording medium 20 side.
Are opposed to each other, and are pressed against the toner carrying roller 14 at the aperture position of the insulating sheet 2.

The positional relationship between the aperture 6 of the aperture electrode body 1 and the toner carrying roller 14 will now be described in detail. As shown in FIG. 3, the center line 30 of each aperture 6 is the toner carrying roller 14. It is arranged so as to pass through the uppermost portion of the peripheral surface of and the central shaft 32 of the toner carrying roller 14. According to this, each aperture 6
Based on the uppermost part of the peripheral surface of the toner carrying roller 14,
By arranging them evenly on the left and right, the distribution of the toner 16 passing through each aperture 6 can be made uniform over the entire area of the aperture. In addition, the wall surface of the aperture 6 and the toner 16
Since the flying direction of the toner is parallel to the flying direction of the toner, it is possible to stably fly the toner.

Further, the aperture electrode body 1 itself has an aperture 6 with respect to the toner carrying roller 14 as shown in FIG.
It is pressed so that it bends to the left and right about the same angle. As a result, the contact area between the aperture electrode body 1 and the toner carrying roller 14 can be increased, and the lower periphery of the aperture 6 can be pressed uniformly to the left and right, so that uneven toner concentration is minimized. Can be suppressed.

Next, the operation of the image forming apparatus configured as described above will be described.

First, by rotating the toner carrying roller 14 and the supply roller 12 in the direction of the arrow shown in FIG. 1, the toner 16 sent from the supply roller 12 is rubbed against the toner carrying roller 14 to be negatively charged. The toner is carried on the toner carrying roller 14. Toner 1 carried
The layer 6 is thinned by the layer regulation blade 18 and charged, and then is conveyed toward the aperture electrode body 1 by the rotation of the toner carrying roller 14. Then, the toner on the toner carrying roller 14 is supplied under the aperture 6 while being rubbed by the insulating sheet 2 of the aperture electrode body 1.

In this state, as shown in the schematic diagram of the print pixel of FIG. 5, when one aperture 6 is formed, the toner 16 is bent to the left and ejected to form one pixel (t ₀
~t _1), when forming one pixel by fly bending toner 16 on the right side (t ₁ ~t _2), if the left and right sides in to fly by bending the toner 16 to form a 2 pixels (t ₂ ~ t ₃ ), a case where no pixel is formed (from t ₃ ), will be described with reference to the timing chart of FIG. 4 and the flowchart of FIG.

First, the CPU 42 forms a deflection electric field leftward in step S1 (hereinafter simply referred to as S1 and other steps are the same). This is because the deflection voltage application circuit 40 applies a voltage of -5 kV to the deflection electrode 3 on the right side in FIG. 2 and applies a voltage of +5 kV to the deflection electrode 3 on the left side.
By controlling.

Next, the CPU 42 determines the printing position in S2, and this time forms a pixel on the left side.
In S3, + 30V is applied to the control electrode 4. By applying such a voltage, the negatively charged toner 16 is pulled up by the control electrode 4, passes through the aperture 6, is bent to the left by the deflection electric field formed to the left, and flies to the left side on the recording medium 20. One dot is formed at

When the CPU 42 determines in S4 that the predetermined timing (Tp / 6 in FIG. 4) has been reached, the deflection electric field is formed rightward in step S5. This is +5 kV on the deflection electrode 3 on the right side in FIG.
Is applied and the deflection voltage applying circuit 40 is controlled so that a voltage of -5 kV is applied to the left deflection electrode 3. Next, the CPU 42 discriminates the print position in S6, and this time forms a pixel on the left side, so −30 V is applied to the control electrode 4 in S7.
When a non-printing electric field of -30 V is applied, the negatively charged toner does not pass through the aperture 6 and is sent on the toner carrying roller 14 as it is, so that dots are formed on the right side of the recording medium 20. Not done.

When the CPU 42 determines in S8 that the predetermined timing (2Tp / 6 in FIG. 4) has been reached, the CPU 42 feeds the recording medium 20 by one dot in step S9, and repeats the operations after S1 three times. Thus, one pixel on the left side consisting of 3 dots is formed.

As described above, at the pixel time Tp required to form one pixel, the direction of the deflection electric field is periodically switched to the left or right at a predetermined timing, and +30 V is applied to the control electrode 4 only when the deflection electric field is directed to the left. By applying, it is possible to form pixels only on the left side of the recording medium 20 with respect to the aperture 6.

Next, as shown in FIG. 4 and FIG.
42, at time t ₁ , when the deflection electric field is leftward, −30V is applied to the control electrode 4 (S10), and when the deflection electric field is rightward, + 30V is applied to the control voltage 4 (S11).
One pixel is formed on the right side of the recording medium 20 with respect to the aperture 6.

Furthermore, from the time t _2, 1 CPU 42 applies a + 30 V to the control electrode 4 regardless of the orientation of the deflection field (S3, S11), the left and right sides on the recording medium 20 relative to the apertures 6 Form pixel by pixel.

[0034] Then, from the time t _3, CPU 42 applies a -30V to the control electrode 4 regardless of the orientation of the deflection field (S10, S7), the recording medium relative to the apertures 6 20
No pixels are formed on either of the upper and left sides.

Then, by repeating the above process, a toner image is formed on the entire surface of the recording medium 20. After that, the formed toner image is fixed on the recording medium 20 by the fixing device 26.

By the above electric field application process, it becomes possible to form arbitrary pixels at the left and right positions on the recording medium 20 with respect to one aperture 6. That is, the control electrodes 4 connected to one driving element 9 can form pixels at different positions. Therefore, it is possible to print pixels with higher resolution without increasing the number of ICs forming the driving element 9.

In the present embodiment, the left and right dots are switched by performing time-divisional driving. However, since the recording medium 20 is intermittently conveyed for each dot formation, the dots are arranged on the left side. The dot formation position in the transport direction of the recording medium 20 does not deviate between the formation of dots and the formation of dots on the right side.

Although the recording medium 20 may be continuously conveyed, when the recording medium 20 is continuously conveyed, the dots on the right side are displaced to the downstream side in the conveying direction of the recording medium 20 with respect to the dots on the left side. I will end up. However, in the present embodiment, since one pixel is formed of three dots, the deviation between the left and right dot formation positions is one dot (1/3 pixel) and is not very noticeable. Then, by increasing the number of dots formed by one pixel, it is possible to make the deviation of the left and right dot formation positions less noticeable. Further, in FIG. 2, the pair of deflection electrodes 3 are arranged in a direction orthogonal to the transport direction of the recording medium 20, but the left deflection electrode 3 is arranged.
If the toner 16 forming the dots on the left side is bent to the left side by the deflection electric field, the toner 16 forming the dots on the right side is deflected when the toner 16 forming the dots on the left side is bent to the left side by the deflection electric field. When it is bent to the right by the electric field, it is also bent to the upstream side in the transport direction, so
It is possible to prevent misalignment of the left and right dots in the carrying direction.

If an insulating toner is used in the image forming apparatus constructed as described above, the toner carrying roller 14 is used.
The insulation between the control electrode 4 and the control electrode 4 is maintained, and the aperture 6 does not cause dielectric breakdown.

In the above process, the control electric field generated by the control electrode 4 is formed between the control electrode 4 and the inside of the aperture 6 and between the aperture 6 and the toner carrying surface of the toner carrying roller 14 which faces the aperture 6. Toner 1
Since the control electric field can be directly applied to 6, the control efficiency is high.

Further, even if a part of the supplied toner 16 receives mechanical force due to sliding with the aperture electrode body 1 and enters the aperture 6 corresponding to the non-image portion, inside the aperture 6 Since it can be controlled so as not to pass through the aperture 6 by the electric field, the toner controllability is good.

Further, since the toner carrying roller 14 and the aperture electrode body 1 are opposed to each other with the toner layer interposed therebetween, they can be arranged at a relatively short distance, so that the control voltage can be lowered and an inexpensive driving element can be provided. Can be used.

In addition, the insulating sheet 2 of the aperture electrode body 1
Is directed toward the toner carrying roller 14 side, so that the toner
Even if 6 is not present, the control electrode 4 and the toner carrying roller 14 do not come into contact with each other and electrically short-circuit, and the drive element is not destroyed.

Further, since the aperture electrode body 1 and the toner 16 on the toner carrying roller 14 are in contact with each other at the entrance portion of the aperture 6, the toner 16 accumulated at the entrance portion of the aperture 6 is not supported. Since the toner 16 is pushed away by the toner sequentially supplied, the toner 16 does not accumulate and bridge to block the aperture 6.

The present invention is not limited to the embodiments described in detail above, and various modifications can be made without departing from the spirit of the invention.

For example, in the above-mentioned embodiment, the control voltage of the aperture corresponding to the non-image portion is set to -30V, but it may be zero voltage. In this case, lower voltage driving is possible.

Although the deflection electric field is set to ± 5 kV in the present embodiment, it may be set to 0 V and 10 kV. In this case, one of the deflection electrodes can be grounded, which facilitates the arrangement.

Further, the deflection electric field may be switched between ± 5 kV and ± 10 kV to control each of the left and right dots at two locations, far and near. In this case, one aperture 6 can form dots at four positions.

Further, although the deflection electrode is formed on the aperture electrode body in the present embodiment, it may be arranged between the aperture electrode body and the image receiving body.

Further, in the present embodiment, a pair of deflection electrodes are arranged, but a deflection electrode may be provided for each aperture and voltage may be applied in synchronization with the control electric field to deflect the toner for printing. In this case, the deflection action can be performed with a lower voltage.

In the above embodiment, the aperture electrode body is used as the toner flow control means.
It is also possible to use a knitted electrode body as described in the specification of US Pat. No. 5,036,341 or an edge electrode body having a recording edge portion described in JP-A-6-255163.

[0052]

As is apparent from the above description, in the image forming apparatus according to the first aspect of the present invention, the charged particles can be deflected in the flight direction by the deflection electric field and adhered onto the recording medium. The resolution can be increased with a simple configuration.

Further, in the image forming apparatus according to the second aspect, the resolution can be increased by simple control.

The image forming apparatus according to claim 3 is
It is possible to reduce the positional deviation between two adjacent pixels formed by deflecting the flight direction.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment embodying the configuration of an image forming apparatus of the present invention.

FIG. 2 is a perspective view illustrating a configuration of an aperture electrode body used in the image forming apparatus.

FIG. 3 is a diagram schematically illustrating a configuration of an aperture electrode body and a toner carrying roller used in the image forming apparatus.

FIG. 4 is a timing chart showing the timing of control voltage application and deflection electric field switching in the image forming apparatus.

FIG. 5 is an explanatory diagram schematically showing pixels printed at the above timing.

FIG. 6 is a flowchart illustrating an operation of a CPU of the image forming apparatus.

[Explanation of symbols]

 1 Aperture Electrode Body 3 Deflection Electrode 4 Control Electrode 6 Aperture 8 Control Voltage Applying Circuit 10 Toner Supply Device 14 Toner Carrier Roller 16 Toner 40 Deflection Voltage Applying Circuit 42 CPU

Claims (3)

[Claims] 1. An electrode array having a plurality of charged particle passage portions through which charged particles pass, the control electrode corresponding to each of the plurality of charged particle passage portions, and an electrode thereof. An image recording system that is provided with a charged particle supply means for supplying charged particles to the charged particle passage portion of the array, and records an image by attaching the charged particles that have passed through the charged particle passage portion of the electrode array to a recording medium. In the device, an electric field generating means for generating a deflection electric field for deflecting the charged particles that have passed through the charged particle passage of the electrode array in a direction substantially the same as the direction in which the charged particle passage is arranged, An image forming apparatus comprising: a control unit for controlling a direction of a deflection electric field generated by the electric field generation unit. 2. The control means switches the direction of the deflection electric field at a predetermined timing, and controls the control voltage applied to the control electrode according to the switching timing. Image forming device. 3. The switching of the direction of the deflection electric field is performed a plurality of times during formation of one pixel.
The image forming apparatus as described in the above.