JPH10258536A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a clear image without generating defective printing due to leakage of toner or the like. SOLUTION: This apparatus comprises an opposing electrode 30 which is placed in opposition to a toner carrier body 10 for carrying toner 12, an insulation substrate 21 placed between the toner carrier body 10 and the opposing electrode 30, a plurality of gates which are provided on the insulation substrate 21 to be passing sections for the toner 12, a control electrode 20 consisting of at least two electrode groups including a first electrode group which is provided at a portion surrounding the gates on the toner carrier body 10 of the insulation substrate 21 and a second electrode group which is provided at a side of the opposing electrode 30 and a control circuit that applies a predetermined voltage corresponding to image data to each of electrode groups in the control electrode 20. The first electrode group and second electrode group in the control electrode 20 are controlled by being divided into a plurality of blocks and the opposing electrode 30 is disposed to be divided corresponding to each of the blocks of the control electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a printing section of a digital copying machine and a facsimile apparatus, a digital printer, a plotter, and the like, and forms an image on a recording medium by flying a developer. About.

[0002]

2. Description of the Related Art As a method for forming a visible image on a recording material such as paper from an electrical signal output from a computer, word processor, facsimile, or the like, an ink jet method using ink, a thermal transfer method for melting and transferring ink, a sublimation method, and the like. There is known an image forming method using an image forming method, an electrophotographic method, or the like.

In recent years, with the increase in speed, image quality, and cost reduction, the use of the ink jet system, which is a relatively simple device configuration in which a print head is integrated in a non-impact system, has been increasing. Since the ink that is liquid is used, bleeding occurs on paper and a good image cannot be obtained.In addition, when performing overprinting in color printing, it is not possible to expect a mixed color due to ink mixing. Therefore, when high quality is required, printing using an electrophotographic toner is employed.

[0004] Printing with toner does not cause bleeding, and a visually excellent image with a dark color tone is obtained. In addition, when a plurality of colors are mixed in colorization, a good mixed color is obtained during the fixing process. For this reason, a direct printing method using toner combining a simple process of an ink jet method and an image using toner has been proposed.

For example, in JP-A-4-135870 and JP-A-7-25057, a plurality of openings are provided for each opening, and a toner passing voltage or a toner shielding voltage is selectively provided. There has been proposed a method of forming an image having a plurality of control electrodes to be applied, controlling passage or blocking of the toner to the opening, and forming an image.

[0006]

However, according to the technique disclosed in Japanese Patent Application Laid-Open No. 4-135870, a back electrode having a magnet body is provided at a position facing the toner passage hole group arrangement position. Although it has a configuration,
Even if the toner is caused to fly only by magnetic force, electrical control is not performed, and the back electrode is divided,
The present invention is different from the basic developer flying principle of controlling toner flight by an electric field, which is the object of the present invention. Further, according to this configuration, a magnetic toner is used as the toner, but it is difficult to colorize the magnetic toner due to the inclusion of a magnetic substance.

Further, Japanese Patent Application Laid-Open No. 7-25057 discloses an insulating substrate, a plurality of first electrodes formed on a first surface of the insulating substrate and separated from each other in a row direction, and a plurality of electrodes disposed on the second surface. A second electrode separated in a column direction and formed to intersect the first electrode; and a first electrode, the second electrode, and the insulating substrate at an intersection of the first electrode and the second electrode. A method of controlling toner flight using a control electrode composed of an opening formed through the first electrode and a connection terminal connected to each of the first electrode and the second electrode for supplying a signal. Have been.

In such a method, since the control electrodes have a so-called matrix configuration, the number of potential switching means such as transistors for switching the potential is significantly larger than a configuration in which the aperture is controlled by one electrode. There is the advantage of being less.
How much the number of potential switching means can be reduced is determined by the number of apertures arranged in the electrode extending in the length direction of the control electrode. The larger the number of apertures arranged in one strip electrode, the smaller the number of potential switching means to be reduced. For example, in a configuration in which the aperture is controlled by one electrode, 3
If 00 dpi, the number of required transistors is 2560
In the case of a matrix configuration described in JP-A-7-25057, for example, the number of electrodes is 644 in the case of a 4-row × 640-column electrode configuration. This is 8 lines x
If the electrode configuration is 320 rows, the number of transistors is 3
It can be reduced to 28 and about half.

However, when the above-described configuration of 4 rows × 640 columns is changed to 8 rows × 320 columns, the length of the control electrodes in the row direction becomes longer. When the length of the control electrode in the row direction becomes longer, for example, when the toner carrier is a cylindrical sleeve, the distance between the control electrode and the toner carrier at the center and at the end changes, and the distance is longer at the center. Short and long at the ends. For this reason, the difference in the intensity of the electric field acting on the toner on the surface of the toner carrier between the central portion and the end portion increases, and the electric field required for toner flight control increases at the end portion. Therefore, the number of power supplies to be used increases and the withstand voltage of the transistors to be used further increases, which leads to an increase in the number of components and an increase in cost.

For example, as a countermeasure for avoiding a problem related to toner flight control due to an increase in the length of the control electrode in the row direction, formation of a toner carrier with a belt member or the like has been studied. However, even if a belt member is used, if the length of the control electrode in the row direction becomes longer, a portion for maintaining the parallelism becomes longer, and the influence of bending and wrinkling of the belt tends to occur, which is not preferable. Furthermore, if a belt is used, an increase in the number of parts, an increase in the size of the apparatus, and an increase in cost cannot be avoided.

The present invention has been made in order to solve the above-mentioned problems, and the length of the control electrode in the row direction does not increase as described above, and the distance between the control electrode and the toner carrier is affected. It is an object of the present invention to provide an image forming apparatus capable of causing toner to fly stably with a uniform electric field over the entire surface of a control electrode without performing the operation.

[0012]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a supply unit having a carrier for carrying a developer of at least one color; a counter electrode disposed to face the carrier; An insulating substrate disposed between the carrier and the counter electrode, a plurality of gates provided on the insulating substrate to serve as a passage portion of the developer; A control electrode composed of at least two or more electrode groups including a first electrode group provided on the support body side of the conductive substrate and a second electrode group provided on the counter electrode side, and individual electrode groups of the control electrodes. Control circuit means for applying a predetermined potential according to at least image data, and by applying a predetermined potential to the electrode group of the control electrode by the control circuit means, between the control electrode and the counter electrode Images are printed on the surface of the transported recording medium. An image forming apparatus for forming a first electrode group and the second electrode group of the control electrode, the division control at least for each of a plurality of blocks.

According to a second aspect of the present invention, in the image forming apparatus, the control of each block of the control electrode and the control of the counter electrode divided corresponding to the control electrode are controlled in synchronization with each other.

According to a third aspect of the present invention, there is provided an image forming apparatus, comprising: a supply unit having a carrier for carrying a developer of at least one color;
A counter electrode disposed to face the carrier, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate and serving as passage portions for the developer. And at least two or more electrode groups including a first electrode group provided on the carrier side of the insulating substrate around the plurality of gates and a second electrode group provided on the counter electrode side. A control electrode, and control circuit means for applying a predetermined potential at least in accordance with image data to each electrode group of the control electrodes, and the control circuit means applies a predetermined potential to the electrode group of the control electrodes. Thereby, in the image forming apparatus that forms an image on the surface of the recording medium conveyed between the control electrode and the counter electrode, each group of one of the first electrode group and the second electrode group is Before the corresponding electrode Each of the groups other than the electrode group is controlled by switching the potential of the developing agent passing through the gate, while having potential switching means for controlling by switching the potential of the developing agent passing through the gate. An image forming apparatus characterized by sharing a potential switching unit.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the divided counter electrodes are each formed of an electrode group having a potential switching means among the first electrode group and the second electrode group of the control electrodes. It is controlled in synchronization with a corresponding block.

According to a fifth aspect of the present invention, in the image forming apparatus, in each block of the control electrode, only the counter electrode corresponding to a block controlling passage of the developer through the gate is provided. It is characterized in that a potential having a polarity opposite to that of the developer is applied.

The image forming apparatus according to claim 6, wherein, in each block of the control electrode, the counter electrode corresponding to a block that blocks the passage of the developer through the gate is applied to the control electrode. It is characterized in that a potential having the same polarity as that of the image agent is applied.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect of the invention, the counter electrode divided and arranged has a potential having a polarity opposite to that of the developer,
It is characterized by having potential switching means for switching between a potential of the same polarity as that of the developer.

The image forming apparatus according to claim 8, wherein the first
Each group of either one of the electrode group and the second electrode group has a potential switching means for controlling the passage of the developer through the gate by switching the potential to the corresponding electrode, and each of the groups. The maximum current supply capacity of the potential switching means is about 70 mA or less.

According to a ninth aspect of the present invention, in any one of the control electrodes sharing the potential switching means, the maximum current supply capability of the potential switching means is about 70 mA or less. And

According to a tenth aspect of the present invention, the maximum current supply capacity of the potential switching means of the divided counter electrodes is about 70 mA or less.

According to the first aspect of the present invention, as described above, the length of the control electrode in the row direction does not increase, and the distance between the control electrode and the toner carrier does not influence.
It is possible to stably fly the toner with a uniform electric field over the entire surface of the control electrode, and it is possible to provide a clear image without causing printing defects such as toner leakage. In addition, due to the configuration of the control electrode according to the present invention, for example, 4
The same effect as in the case of an electrode configuration of 8 rows × 320 columns can be obtained with an electrode configuration of rows × 640 columns, and the number of components such as transistors can be significantly reduced.

Further, by forming the counter electrode so as to be divided so as to correspond to each block of the control electrode, for example, when the control electrode blocks toner in the block, If a potential in the direction in which toner flies is applied to the counter electrode corresponding to the position corresponding to the block, the toner leaks out of the block in which the toner is blocked by the potential of the counter electrode. Can also be solved, and an image with good print quality can be provided.

According to the second aspect of the present invention, the control of each block of the control electrode and the control of the counter electrode divided corresponding to the control electrode are controlled in synchronization with each other, so that the control of the toner flying is performed. It can be performed efficiently and accurately.

According to the third aspect of the present invention, each of the first electrode group and the second electrode group is connected to the corresponding electrode by the potential of the developer passing through the gate. And each group other than the electrode group shares a potential switching means for controlling by switching the potential of the developer passing through the gate, thereby controlling the potential. The number of parts of the switching means can be reduced, and the size and cost of the device can be reduced.

According to the configuration of the fourth aspect, the divided counter electrodes are formed into electrode groups each having a potential switching means among the first electrode group and the second electrode group of the control electrodes. By controlling in synchronization with the corresponding block, toner flight control can be performed efficiently and accurately.

According to a fifth aspect of the present invention, in each block of the control electrode, only the counter electrode corresponding to a block controlling passage of the developer through the gate is provided. By applying a potential of the opposite polarity to the developer,
It is possible to accurately control the toner flight and to provide a clear image without causing printing defects such as toner leakage.

According to the configuration of the sixth aspect, in each of the blocks of the control electrode, the counter electrode corresponding to the block in which the passage of the developer through the gate is prevented. By applying a potential having the same polarity as that of the image agent, the flying control of toner can be accurately performed, and a clear image can be provided without causing printing defects such as toner leakage.

According to the seventh aspect of the present invention, the divided counter electrode has a potential switching means for switching between a potential having a polarity opposite to that of the developer and a potential having the same polarity as the developer. As a result, the control circuit configuration becomes compact, and the size and cost of the device can be reduced.

According to the eighth aspect of the present invention, each of the first electrode group and the second electrode group is configured to apply a potential to the corresponding electrode by passing the developer through the gate. , Each of which has a maximum current supply capability of about 70 mA or less, to provide a safe and highly reliable device that complies with safety standards. be able to.

According to the configuration of the ninth aspect, in one of the electrode groups of the control electrodes sharing the potential switching means, the maximum current supply capability of the potential switching means is about 70 mA or less. It is possible to provide a safe and highly reliable device that complies with safety standards.

According to the tenth aspect of the present invention, the maximum current supply capacity of the potential switching means of the divided counter electrodes is set to about 70 mA or less, so that safety standards are observed, and safety and reliability are ensured. High device can be provided.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following description, an image forming apparatus having a configuration corresponding to a negatively charged toner will be described in detail. However, when a positively charged toner is used, the polarity of each applied voltage may be appropriately set accordingly. .

FIG. 1 shows a cross section of a printer equipped with an image forming apparatus according to an embodiment of the present invention. The outline of each element will be described with reference to FIG.

As shown in FIG. 2, the printing unit 102 prints an image corresponding to an image signal from a host computer (not shown).
The image is visualized on a sheet 8 as a recording medium using a toner 12 as a developer. That is, the image forming apparatus forms an image directly on paper by controlling the flight of the toner 12 based on the image signal.

A paper supply unit 101 is provided on the side where paper enters the image forming unit 3. The paper supply unit 101 includes a paper cassette 7 that stores paper 8 as a recording medium, a pickup roller 5 that sends out the paper 8 from the paper cassette 7, a paper feed guide (not shown) that guides the supplied paper 8, and a pair of resists. Consists of rollers. Also, the paper feed unit 1
Reference numeral 01 includes a paper feed sensor (not shown) for detecting that the paper 8 has been supplied. Pickup roller 5
Are driven by a driving device (not shown). A fixing unit 103 that fixes the toner image formed on the paper 8 by the image forming unit 3 to the paper 8 by heating and pressing is provided on the paper output side of the paper 8 from the image forming unit 3. ing. The fixing unit 103 includes a heater 40 and a heating roller 4.
1, a pressure roller 42, a temperature sensor 43, and a temperature control circuit 54. The heating roller 41 is made of, for example, an aluminum tube having a thickness of 2 mm. The heater 40 is made of, for example, a halogen lamp and is built in the heating roller 41.

The pressure roller 42 is made of, for example, a silicone resin. A 2-kg load is applied to both ends of each shaft by a spring or the like (not shown) so that the heating roller 41 and the pressure roller 42 provided opposite to each other can be pressed with the paper 8 therebetween. Have been. The temperature sensor 43 measures the temperature of the surface of the heating roller 41. The temperature control circuit 54 is controlled by a main control unit described later, and controls ON / OFF of the heater 40 based on the measurement result of the temperature sensor 43 to maintain the surface temperature of the heating roller 41 at, for example, about 150 ° C. I do.

The fixing section 103 has a paper discharge sensor (not shown) for detecting that the paper 8 has been discharged.
The materials of the heater 40, the heating roller 41, the pressure roller 42, and the like are not particularly limited. Further, the temperature of the surface of the heating roller 41 is not particularly limited. Further, the fixing unit 103 may be configured to fix the toner image by heating or pressing the sheet 8.

Although not shown, a discharge roller for discharging the paper 8 processed by the fixing unit 103 onto a discharge tray, and a discharged paper 8 on the output side of the paper 8 from the fixing unit 103. A receiving tray is provided. The heating roller 41, the pressure roller 42, and the paper discharge roller are driven by a driving device (not shown).

The toner supply unit 4 of the image forming unit 3 includes a toner storage tank 1 in which a toner 12 as a developer is stored.
1. A toner carrier 10 serving as a cylindrical carrier (sleeve) for carrying the toner 12 by magnetic force and provided inside the toner storage tank 11 to charge the toner 12 and to be carried on the outer peripheral surface of the toner carrier 10 And a doctor blade 13 for regulating the thickness of the toner layer. The doctor blade 13 is provided on the upstream side in the rotation direction of the toner carrier 10 so that the distance from the outer peripheral surface of the toner carrier 10 is, for example, about 60 μm.

The toner 12 has, for example, an average particle size of about 6 μm.
The toner is charged by the doctor blade 13 so that the charge amount is, for example, about −4 μC / g to about −5 μC / g. The doctor blade 13
The distance between and the toner carrier 10 is not particularly limited. Further, the average particle size and the charge amount of the toner 12 are not particularly limited.

The toner carrier 10 is driven by a driving device (not shown) and rotates in the direction of arrow A in the figure, for example, at a surface speed of about 80 mm / sec. The toner carrier 10 is grounded, and magnets (not shown) are arranged inside the toner carrier 10 at positions facing the doctor blade 13 and control electrodes 20 described later. Thus, the toner carrier 10 can carry the toner 12 on its outer peripheral surface.

The toner 12 carried on the outer peripheral surface of the toner carrier 10 forms ears at positions corresponding to the positions on the outer peripheral surface. The rotation speed of the toner carrier 10 is not particularly limited. Further, the toner carrier 10 may be configured to carry the toner 12 by electric force or electric force and magnetic force instead of carrying the toner 12 by magnetic force.

The printing section of the image forming section 3 has a thickness of about 1
a counter electrode 30, which is made of an aluminum plate having a thickness of 2 mm and faces the outer peripheral surface of the toner carrier 10, a counter electrode power supply 52 for supplying a high voltage to the counter electrode 30,
And a fan motor 6 that sucks and conveys the paper 8 by a suction force.

Here, the image forming process of the present image forming apparatus will be described. First, upon receiving a signal from a host computer (not shown), the main controller of the printer starts an image forming operation. That is, the image data, which is information of the host computer, is converted into an array pattern of control electrodes, and then sent to the control electrode control unit.

The main control unit of the printer operates a drive unit (not shown), and the paper 8 in the paper cassette 7 is sent out toward the image forming unit 3 by the pickup roller 5 which is driven to rotate by the drive unit. The paper feed state is detected by the paper feed sensor. The sheet 8 sent out by the pickup roller 5 is conveyed to the image forming section 3.

Thereafter, a signal is output from the control electrode control section in accordance with the image data, and a voltage is applied to the control electrode by each potential switching means. This applied voltage is applied to, for example, about 150 V or about -200 V to control the electric field near the control electrode. That is, at the gate of the control electrode, the prevention and the release of the flying of the toner 12 from the toner carrier 10 to the counter electrode 30 are appropriately performed according to the image data. As a result, about 30 mm /
A toner image corresponding to the image signal is formed on the paper 8 moving at the speed of sec. Paper 8 on which toner image is formed
Is transported to the fixing unit 103, and the toner image is fixed on the sheet 8 by the fixing unit 103. The paper 8 on which the toner image has been fixed is discharged onto a paper tray by a paper discharge roller, and a normal discharge is detected by a paper discharge sensor. Based on this detection operation, the main control unit of the printer determines normal end of the printing operation.

By the above image forming operation, a good image is formed on the sheet 8. Since the present image forming apparatus forms an image directly on the sheet 8, a visualizing member such as a photoconductor or a dielectric drum used in a conventional image forming apparatus is not required. Accordingly, the transfer operation for transferring the image from the visualized object to the sheet 8 is omitted, so that the image does not deteriorate. For this reason, the reliability of the device is improved, the configuration of the device is simplified, and the number of components is reduced, so that the device can be reduced in size and cost.

Here, the configuration of the control electrode 20 according to the present invention will be described. The control electrode 20 is two-dimensionally spread parallel to the tangential direction of the surface of the counter electrode 30 and opposed to the counter electrode 30.
The structure is such that the toner flow in the zero direction can pass. The electric field applied to the toner 12 on the surface of the toner carrier 10 changes according to the potential supplied to the control electrode 20, and the toner flying from the toner carrier 10 to the counter electrode 30 is controlled.

The control electrode 20 includes an insulating substrate 21, a ring-shaped electrode 22 which is an independent ring-shaped conductor, and a plate-shaped shield electrode provided with an opening corresponding to each ring-shaped electrode 22. 23. Control electrode 2
Each of the electrodes such as the shield electrode 23 is a control electrode voltage power supply 5.
Connected to 0.

The control electrode 20 is provided so that the distance from the outer peripheral surface of the toner carrier 10 is, for example, about 100 μm, and is fixed by a support member (not shown). As shown in FIG. 3, the control electrode 20 is an insulating substrate 21,
Potential switching means 230-1, 230-2, 230-3,
230-4, 240, 250-1, 250-2, 250
-3, 250-4 and independent strip-shaped conductors, that is, strip-shaped electrodes 200a-1, 200a-2,...
a-320, 200b-1, 200b-2,... 20
0b-320, 210-1, 210-2, 210-3,
210-4, 220-1, 220-2, 220-3, 2
20-4.

The insulating substrate 21 is made of, for example, a polyimide resin and has a thickness of about 25 μm. Further, a hole to be a gate is formed in the insulating substrate 21.

The strip electrodes 200a-1, etc., 200b-1
And 210-1 etc., 220-1 etc. are made of, for example, copper foil and are provided on the surface of the insulating substrate 21 on the toner carrier 10 side and the counter electrode 30 side, that is, around the hole, and They are arranged according to the array. Each strip electrode 2
00a-1 etc., 200b-1 etc., 210-1 etc., 220
For example, -1 is formed to have a diameter of about 220 μm and a thickness of about 30 μm. In addition, the band-shaped electrode 200a-1, etc.
The openings such as b-1, 210-1 and 220-1 have a diameter of about 200 μm, for example, and serve as a passage for the toner 12 flying from the toner carrier 10 to the counter electrode 30. The counter electrode 30 is connected to a counter electrode voltage power supply 52. Here, this passing portion is hereinafter referred to as a gate.
Note that the distance between the control electrode 20 and the toner carrier 10 is not particularly limited. Also, the size of the gate, the insulating substrate 21 and the strip electrodes 200a, 200b, 21
The material and thickness of 0 and 220 are not particularly limited.

For example, 2560 gates are formed, and each of the strip electrodes 200a-1, 200b-1, etc.
210-1 etc., 220-1 etc. are electrically connected to a high voltage driver as a potential switching means via a feeder line. The number of the gates corresponds to a resolution of 300 dpi (dot per inch) in the width of A4 size paper. The strip electrodes 200a-1 and the like, 200b-1
, 210-1 etc., 220-1 etc. are not particularly limited.

The belt-like electrodes 200a-1, etc.
The surface of 0b-1, etc., 210-1, etc., 220-1 etc. and the surface of the feeder line are covered with an insulator layer (not shown) having a thickness of about 30 [mu] m. ,
Insulation between 200b-1 etc., 210-1 etc., 220-1 etc., insulation between feeders, and strip-shaped electrodes 200a-1 etc., 200b-1 etc., 210- not connected to each other
Insulation between the power supply line and the first and the like, 220-1 and the like is ensured. The material and thickness of the insulator layer are not particularly limited.

In one embodiment of the present invention shown in FIG. 3, so-called row electrodes 210-1 and so on, 220-1 and so on
00a-1 and the like, 200b-1 and the like constitute a 4 × 640 matrix. In this embodiment mode, a transistor is used as the potential switching means. In addition, the circuit must be configured such that the maximum current when the current consumption of all the transistors is equal to or less than about 70 mA in the current consumption required for switching of this transistor. This is because there are such restrictions in safety standards. Therefore, each potential switching means of the control electrode 20 and the counter electrode 3
The circuit is configured so that the zero potential switching means does not deviate from this standard.

Eight row electrodes 210-1 to 4-4 and 220-1 to 4-4 form a group of four, and each is controlled by eight-channel potential switching means composed of eight transistors. I have. Column electrodes 200a-1 to 320,
The groups 200b-1 to 320 form a group of 320 transistors, and the potential switching means of 64 channels in which 64 transistors are built in a single-chip IC is controlled by five. The column electrodes 200a, 200b are 200a-1 and 20
One electrode of each group is controlled by one channel of the potential switching means of 64 channels such as 0b-1, 200a-2 and 200b-2.

Here, specifically, the gate 300-1 of FIG.
When the gates 300 and 320 are ON and the other gates 300 are OFF, the following control is performed. First, the potential switching means 230
The row electrode 210-1 is turned ON, and the other row electrodes 210-
2-4 and 220-1-4 are OFF, potential switching means 24
By 0, the column electrodes 200a-1 and 200b-1 are ON,
200a-2 to 320, 200b-2 to 320 are OFF
First, the gate 300-1 for which both rows are ON is printed.

Next, the row electrode 220-1 is turned on by the potential switching means 250, and the other row electrodes 210-1 to 4-4 and 220 are turned on.
-2-4 are OFF, column electrodes 200a-1, 200b-1
Is ON, 200a-2 to 320, 200b-2 to 320
Is turned OFF, and the gate 300-
320 is printed.

In the prior art, 644 transistors are used in 4 × 640 matrix control.
According to the present embodiment, control similar to the conventional control can be realized with 328 pieces. As described above, in the present embodiment, in the 4 × 640 matrix control, the number of transistors conventionally required can be reduced to about half.

Further, conventionally, when the electrode configuration is an 8 × 320 matrix configuration in order to reduce the potential switching means, the number of row electrodes is doubled and the width of the control electrodes 20 is widened. When the width of the control electrode is widened, the distance between the toner carrier 10 and the control electrode 20 is different between the central portion and the end portion due to the curvature of the toner carrier 10. In this case, the electric field sensed by the toner 12 carried on the surface of the toner carrier 10 has a large difference between the portion facing the center of the control electrode 20 and the portion facing the end. For example, the electric field at the portion opposing the center portion of the control electrode 20 and the electric field at the portion opposing the end portion become weaker at the portion opposing the end portion, so that the flying control of the toner 12 may be difficult. In the worst case, flight control becomes impossible.

The configuration of the control electrode 20 according to the present invention can also solve such a problem, and can greatly reduce the number of transistors described above without increasing the width of the control electrode.

Here, the configuration of the counter electrode 30 arranged to face the control electrode 20 will be described. The counter electrode 30 according to the present invention is divided so as to correspond to each block of the control electrode.

For example, in the control electrode 20 described above, as shown in FIG.
4 are divided into two groups of four, and the column electrodes 200a-1 to 320, 200b-1
３２０320 are divided into two groups. At this time, the opposing electrode 30 opposes the control electrode 2 as shown in FIG.
0 so as to correspond to each group of 0.
a, 30-b.

At this time, the gate 300-1 shown in FIG.
The control of the counter electrodes 30-a and 30-b will be described below along with the control when the gates 300 and 320 are ON and the other gate 300 is OFF.

First, the row electrode 210-1 is turned on by the potential switching means 230, and the other row electrodes 210-2 to 4-4 and 22 are turned on.
0-1 to 4 are OFF, the column electrodes 200a-1 and 200b-1 are ON by the potential switching means 240, and 200a-2.
To 320 and 200b-2 to 320 are turned off, and the potential of the opposite electrode 30-a is opposite to that of the toner 12, that is, the toner 12 in the present embodiment uses negatively charged toner. A positive potential is applied to −a, a potential of the same polarity as the toner 12 is applied to the counter electrode 30 -b,
That is, a negative potential is applied, the matrix is first turned on, and the opposite polarity of the toner 12 is applied to the opposing electrode to print the gate 300-1.

Here, the counter electrode 30-a disposed opposite to the block where the gate 300-1 is located is the toner 30 carried on the toner carrier 10 on the counter electrode 30-a. In order to cause the toner 12 to be attracted in the direction of the counter electrode in order to fly onto the paper 8 as a recording medium passing over the counter electrode, a potential must be applied.

On the other hand, the blocks (row electrodes 220-1 to 220-4,
200b-1 to 200), when the toner 12 passes through the gate, the toner 12 drops on a portion of the sheet 8 where the toner 12 should not fly due to the image signal, and a printing defect such as toner leakage occurs. Therefore, in order to hold the toner 12 carried on the toner carrier 10 on the surface of the toner carrier 10, the opposite electrode 30-b has the same polarity as the toner 12, which is a potential in a direction repelling in the direction of the opposite electrode. Apply potential.

Next, the row electrode 220-1 is turned on by the potential switching means 250, and the other row electrodes 210-1 to 4-4 and 220 are turned on.
-2-4 are OFF, column electrodes 200a-1, 200b-1
Is ON, 200a-2 to 320, 200b-2 to 320
Is turned off, and the potential of the opposite polarity to the toner 12 is applied to the counter electrode 30-b, that is, since the toner 12 in this embodiment uses a negatively charged toner, the potential of the positive polarity is applied to the counter electrode 30-b. The toner 12 is applied to the counter electrode 30-a.
A potential having the same polarity as the above, that is, a potential having a negative polarity is applied, the matrix is turned ON, and a potential having a polarity opposite to that of the toner 12 is applied to the opposing electrode, and the gates 300 to 320 are printed.

In the case where the control electrode 20 according to the present invention has a divided electrode configuration, when the counter electrode 30 is not divided but is configured by one counter electrode facing the entire control electrode, For example, when printing the gate 300-1 in the above-described control, the row electrode 210-1 is turned on by the potential switching means 230, and the other row electrodes 210-2 to 210-3 are turned on.
4 and 220-1 to 4-4 are OFF, and the column electrodes 200a-1 and 200b-1 are ON by the potential switching means 240.
0a-2 to 320 and 200b-2 to 320 are turned off.

Here, the blocks (row electrodes 220-1 to 220-4, column electrodes 200b-
In (1) to (320), all the row electrodes are turned off.
Since the column electrode 200b-1 is ON, a slight flying electric field is formed at the gate corresponding to the column electrode 200b-1. This is because the column electrodes 200a and 200b
00a-1 and 200b-1, 200a-2 and 200b-
2. One of 64 channels of potential switching means such as
This is caused because one electrode of each group is controlled by the channel. However, such a configuration is indispensable for reducing the number of transistors as described above, and it is necessary for the control configuration. There is no problem at all.

However, since a slight flying electric field is formed as described above, the toner 1 carried on the toner carrier 10
2 may fly due to this electric field. In the single-electrode counter electrode, a potential is applied in a direction that uniformly attracts the toner 12 toward the counter electrode over the entire surface of the control electrode, and further promotes a slight flying electric field formed at the gate corresponding to the column electrode 200b-1. As a result, the possibility that the toner 12 carried on the toner carrier 10 flies due to this electric field increases.

As a means for solving this problem, in the present invention, the counter electrode is divided and arranged in accordance with the division of the control electrode, so that the toner 12 falls off at the gate where the toner 12 should not fly as described above. Can be prevented.

Further, by applying a potential having the same polarity as that of the toner 12 to the opposite electrode of the block in which the toner flight control is not performed, the effect is extremely large, and printing failure due to toner leakage does not occur.

In the image forming apparatus according to the present invention, the paper 8 as the recording medium is conveyed by the fan motor 6 adsorbed on the paper conveyance supporting member by air flow. This paper 8
There are two methods of transporting the paper 8: a method in which the paper 8 is charged on a support member formed of a dielectric or the like and the paper 8 is electrostatically attracted to the support member and transported, and a method in which the paper 8 is transported by suction using an air flow. .

In the former transport by electrostatic attraction, the potential difference between the dielectric member and the sheet 8 is a point. In the configuration according to the present invention, both positive and negative potentials are applied to the opposite electrode. It is not preferable because it is difficult to charge and convey the paper 8 passing therethrough, and there is a possibility that a problem such as leakage may occur.

For this reason, in the image forming apparatus according to the present invention, the latter suction conveyance by air is suitable. In this case, for example, the fan motor 6 which is an air generating means has a counter electrode which is not likely to affect printing. It is arranged on the back side. In this case, a ventilation hole for passing this air flow is required before and after the counter electrode or the counter electrode.

Therefore, in the present invention, the counter electrode which is divided and arranged or a large number of ventilation holes are provided before and after the counter electrode so that the sheet 8 can be properly sucked. At this time, the vent holes need to be minute holes so as not to affect the formation of the electric field in order to form an electric field required for flying the toner over the entire surface of the counter electrode. Further, the divided counter electrode or a large number of ventilation holes provided before and after the counter electrode are formed such that the upstream side is larger than the downstream side with respect to the airflow blown in the direction of the counter electrode. Thus, the air flow for adsorbing the paper 8 can be made to act efficiently.

As described above, according to the present invention, the number of parts can be greatly reduced, whereby the size and cost of the apparatus can be reduced, and a clear image can be provided without causing printing defects such as toner leakage. can do.

In addition, the present invention is not limited to the embodiment described above and shown in the drawings, and it is needless to say that the present invention can be appropriately modified and implemented without departing from the scope of the invention.

[0081]

According to the first aspect of the present invention, there is provided a supply means having a carrier for carrying a developer of at least one color;
A counter electrode disposed to face the carrier, an insulating substrate disposed between the carrier and the counter electrode, and a plurality of gates provided on the insulating substrate and serving as passage portions for the developer. And at least two or more electrode groups including a first electrode group provided on the carrier side of the insulating substrate around the plurality of gates and a second electrode group provided on the counter electrode side. A control electrode, and control circuit means for applying a predetermined potential at least in accordance with image data to each electrode group of the control electrodes, and the control circuit means applies a predetermined potential to the electrode group of the control electrodes. Thereby, in the image forming apparatus that forms an image on the surface of the recording medium conveyed between the control electrode and the counter electrode, the first electrode group and the second electrode group of the control electrode are provided at least for each of a plurality of blocks. Split control Both the counter electrode, by arranging the split so as to correspond to each block of the control electrode, it is possible to provide a clear image without generating a defective printing toner leakage and the like.

According to the second aspect of the present invention, the control of each block of the control electrode and the control of the counter electrode divided corresponding to the control electrode are controlled in synchronization with each other, so that the control of the toner flying is performed. It can be performed efficiently and accurately.

According to the third aspect of the present invention, each of the first electrode group and the second electrode group is connected to the corresponding electrode by the potential of the developer passing through the gate. And each group other than the electrode group shares a potential switching means for controlling by switching the potential of the developer passing through the gate, thereby controlling the potential. The number of parts of the switching means can be reduced, and the size and cost of the device can be reduced.

According to the fourth aspect of the present invention, the divided counter electrodes are arranged such that each of the first electrode group and the second electrode group of the control electrode has an electrode switching means. By controlling in synchronization with the corresponding block, toner flight control can be performed efficiently and accurately.

According to a fifth aspect of the present invention, in each block of the control electrode, only the counter electrode corresponding to the block controlling passage of the developer through the gate is provided. By applying a potential of the opposite polarity to the developer,
It is possible to accurately control the toner flight and to provide a clear image without causing printing defects such as toner leakage.

According to the configuration of the sixth aspect, in each of the blocks of the control electrode, the counter electrode corresponding to the block that blocks the passage of the developer through the gate is applied to the counter electrode. By applying a potential having the same polarity as that of the image agent, the flying control of toner can be accurately performed, and a clear image can be provided without causing printing defects such as toner leakage.

According to a seventh aspect of the present invention, the divided counter electrodes have potential switching means for switching between a potential having a polarity opposite to that of the developer and a potential having the same polarity as the developer. As a result, the control circuit configuration becomes compact, and the size and cost of the device can be reduced.

According to the eighth aspect of the present invention, each of the first electrode group and the second electrode group is connected to the corresponding electrode by passing the developer through the gate at a potential. , Each of which has a maximum current supply capability of about 70 mA or less, to provide a safe and highly reliable device that complies with safety standards. be able to.

According to the configuration of the ninth aspect, in one of the electrode groups of the control electrodes sharing the potential switching means, the maximum current supply capability of the potential switching means is about 70 mA or less. It is possible to provide a safe and highly reliable device that complies with safety standards.

According to the tenth aspect of the present invention, the maximum current supply capacity of the potential switching means of the counter electrode divided and arranged is about 70 mA or less, thereby complying with safety standards, ensuring safety and reliability. High device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a main part of an image forming unit according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a control electrode according to one embodiment of the present invention.

FIG. 4 is a diagram showing an arrangement state of a control electrode and a counter electrode according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Toner carrier 12 Toner 20 Control electrode 21 Insulating substrate 30 Counter electrode 230-1, 230-2, 230-3, 230-4 Potential switching means 240, 250-1, 250-2, 250-3, 250
-4 Potential switching means

Claims (10)

[Claims] 1. A supply means having a carrier for carrying a developer of at least one color, a counter electrode arranged opposite to the carrier, and an insulating member arranged between the carrier and the counter electrode. A substrate, a plurality of gates provided on the insulating substrate as passing portions of the developer, and a first electrode group provided around the plurality of gates and on the carrier side of the insulating substrate. A control electrode composed of at least two or more electrode groups including a second electrode group provided on the counter electrode side, and a control circuit for applying a predetermined potential corresponding to at least image data to each of the control electrode groups Means for forming an image on the surface of a recording medium conveyed between the control electrode and the counter electrode by applying a predetermined potential to an electrode group of the control electrode by the control circuit means In the above control electric The first electrode group and the second electrode group are divided and controlled at least for each of a plurality of blocks, and the counter electrode is divided and arranged so as to correspond to each block of the control electrode. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the control of each block of the control electrode and the control of the counter electrode divided corresponding to the control electrode are controlled in synchronization with each other. 3. A supply means having a carrier for carrying a developer of at least one color, a counter electrode arranged opposite to the carrier, and an insulating member arranged between the carrier and the counter electrode. A substrate, a plurality of gates provided on the insulating substrate as passing portions of the developer, and a first electrode group provided around the plurality of gates and on the carrier side of the insulating substrate. A control electrode composed of at least two or more electrode groups including a second electrode group provided on the counter electrode side, and a control circuit for applying a predetermined potential corresponding to at least image data to each of the control electrode groups Means for forming an image on the surface of a recording medium conveyed between the control electrode and the counter electrode by applying a predetermined potential to an electrode group of the control electrode by the control circuit means In the first electronic device, Each of the electrode groups of one of the group and the second electrode group has a potential switching means for controlling by switching the potential of the developer passing through the gate to the corresponding electrode, and the electrode group The image forming apparatus is characterized in that the other groups share a potential switching unit that controls by switching the potential of the developer through the gate. 4. The divided counter electrode is controlled in synchronization with a block corresponding to an electrode group having a potential switching means in each of the first electrode group and the second electrode group of the control electrode. The image forming apparatus according to claim 1, wherein the image forming apparatus performs the image forming process. 5. A potential having a polarity opposite to that of the developer only for the counter electrode corresponding to a block controlling passage of the developer through the gate in each block of the control electrode. The image forming apparatus according to claim 1, wherein: 6. A potential of the same polarity as that of the developer is applied to the counter electrode corresponding to a block in which control of the passage of the developer through the gate is performed in each block of the control electrode. 4. The voltage is applied.
The image forming apparatus according to any one of the above. 7. The divided counter electrode has a potential switching means for switching between a potential having a polarity opposite to that of the developer and a potential having the same polarity as that of the developer. The image forming apparatus according to claim 3. 8. A potential switch for controlling the passage of the developer through the gate to a corresponding electrode by switching a potential of a corresponding one of the first electrode group and the second electrode group. 4. The image forming apparatus according to claim 1, wherein each of the potential switching means has a maximum current supply capability of about 70 mA or less. 9. A method according to claim 1, wherein a maximum current supply capability of said potential switching means is about 70 mA or less in one of said control electrode groups sharing said potential switching means. 3. The image forming apparatus according to any one of 3. 10. The image forming apparatus according to claim 1, wherein a maximum current supply capability of the potential switching means of the divided counter electrodes is about 70 mA or less.