JPH11301006A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep an image forming state well by accurately controlling through-holes for flying toner. SOLUTION: A plurality of rows of through-holes 22, wherein one row comprises four through-holes 22 arranged linearly in the direction inclined by a predetermined angle with respect to the feed direction of a recording medium, are formed to a flight control part 2 in the direction crossing the feed direction of the recording medium at a right angle. Ring-shaped control electrodes 23 are formed to the respective edge parts of the through-holes 22 and the control electrodes 22 of each row are connected by strip-like electrodes 24. Cylindrical toner carriers 45-48 are arranged under four through-holes 22 contained in one row. The toner carrier 45 supports the toner on its peripheral surface. A flight electric field is formed in the through-holes 22 corresponding to the positions where potential at the time of formation of the flight electric field is applied to both of a plurality of the strip-like electrodes and a plurality of the toner carriers 45-48 and toner flies from the surfaces of the toner carriers 45-48 through these through-holes 22.

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 for forming an image by flying toner on a toner carrier to a recording medium via a through hole in which a flying electric field is formed.

[0002]

2. Description of the Related Art In a conventional image forming apparatus such as a digital copying machine, a surface of a photoreceptor uniformly charged in advance is irradiated with image light to form an electrostatic latent image by photoconductive action. In general, an image is formed by so-called electrophotography in which a toner image formed by electrostatically adsorbing toner onto a recording medium is transferred to the surface of a recording medium. In the image formation using the electrophotographic method, an adverse effect on the environment due to ozone generated at the time of corona discharge in a step of charging the surface of the photoreceptor and the like, and an increase in the size of the structure for performing a number of steps and an image There is a problem that the forming time is lengthened.

Therefore, there have been proposed a large number of direct recording type image forming apparatuses which form an image by directly flying toner onto a recording medium through a through hole in which an electric field is selectively formed. In this direct recording type image forming apparatus, the potential of electrodes disposed in each of a large number of through holes is switched to control the flight of toner passing through the through holes to form an image on the surface of a recording medium. In this case, if the potentials of the electrodes arranged in each of the through holes are controlled independently, a number of potential switching means (hereinafter referred to as FETs) as many as the number of through holes are required.

For this reason, as disclosed in Japanese Patent Application Laid-Open No. Hei 6-91918, two-way electrode groups each passing through a plurality of through-holes are arranged so as to cross each other in each through-hole, and are arranged in two directions. A matrix-driven direct recording method has been proposed in which a through hole through which toner flies is selected from a plurality of through holes by a combination of electrodes that apply a flight control potential in each of the electrode groups. In this matrix driving method, the number of FETs to be arranged can be reduced, and cost reduction can be realized.

However, in the matrix-driven direct recording method, the toner should originally pass only through the through-hole where a predetermined ON potential is applied to both of the electrodes in the two directions that intersect. The toner also passes through a through-hole to which only one of the two-way electrodes is applied with the ON potential, and leaks toner to generate a deterioration in contrast due to fogging and poor image quality due to color mixing during color image formation. Invite. Further, when the leakage toner is generated in the through hole where the recording medium does not face, the leakage toner adheres to the counter electrode provided facing the through hole, and stains the back surface of the recording medium that passes later, Changes in the apparent potential of the toner, causing poor toner flight. Furthermore, if the leaked toner adheres to the inside of the control electrode or the through-hole near the through-hole, a change in the apparent potential of the control electrode or clogging of the through-hole occurs, resulting in an image drop due to defective toner flight. There's a problem.

In order to solve these problems, it is conceivable to apply a predetermined off-potential to an electrode located in a through-hole through which toner should not pass. Since the potential difference between the off state and the off state becomes large, it is necessary to sufficiently increase the withstand voltage of the FET, resulting in an increase in cost. Although it is conceivable to reduce the opening diameter of the through-hole on the counter electrode side, the on-potential must be sufficiently large in order to secure the effect of the electrode potential in the recording medium.
It is necessary to sufficiently increase the pressure resistance of T, resulting in an increase in cost. Furthermore, a method of approaching the control electrode to the recording medium, or a method of reducing the interval between the matrix electrodes is conceivable, but maintaining the conveyance position accuracy of the recording medium, and
This leads to an increase in cost and a decrease in yield for maintaining insulation between the electrodes. In addition, it is conceivable to control the physical properties of the toner to be used, but it is not easy to control the physical properties of the toner such as the charge amount, and the feasibility is extremely low in consideration of the influence on the environment and the change with time.

For these reasons, Japanese Patent Application Laid-Open No. Hei 6-22702 discloses
No. 2, discloses a configuration in which a toner carrying belt 127 disposed between a column electrode 101 and a row electrode 125 constituting a control electrode for matrix driving is provided as shown in FIG. With this configuration, the toner carrying belt 1
It is said that a control electric field is formed in the toner supply path constituted by 27, the efficiency of the control voltage is increased, the image forming speed is increased, and the loss of an image due to the blocking of the through hole can be prevented. ing.

[0008]

However, in the configuration disclosed in Japanese Patent Application Laid-Open No. 6-227022, when the belt-shaped toner carrier is made of a high-resistance material, the toner carrier itself is charged. As a result, the potential on the surface changes, the surface potential of the toner becomes unstable, the switching of the control electric field formed between the toner carrier and the control electrode becomes insufficient, and the passage of the toner through the through-hole is accurately performed. There is a problem that cannot be controlled. In addition, since the toner carrier is passed between the row electrode and the column electrode with a short interval, the toner carrier floating during the movement comes into contact with or comes close to the column electrode located above, and the control electrode is short-circuited. To cause damage to the control circuit. On the other hand, when the toner carrier is made of a low-resistance material, electrostatic shielding is caused by the toner carrier floating from the row electrode during movement, and a control electric field is not formed between the toner carrier and the column electrode. You will not be able to fly. For this reason, it is necessary to keep the toner carrier in close contact with the row electrodes, but it is often mechanically difficult to always keep the toner carrier in close contact with all of the plurality of row electrodes, which increases the cost and reduces the yield. Invite you. Furthermore, when a potential difference occurs between the row electrodes, the toner carrier may be damaged due to heat generation. If the tolerance of the resistance value is narrow, and the environmental change and the aging of the resistance value are considered, the toner carrier may be damaged. The choice of materials is extremely difficult.

Further, in the case of performing the direct recording type image formation irrespective of the single drive or the matrix drive, the diameter of the through hole is equal to or larger than the dot diameter of the image formed on the recording medium. A ring-shaped or band-shaped electrode is arranged at the edge of the through hole. For this reason, the plurality of through holes cannot be arranged in a line in a direction orthogonal to the transport direction of the recording medium due to geometric reasons, and it is necessary to arrange the through holes obliquely in a predetermined range in the transport direction of the recording medium. In addition, the through holes adjacent to each other are arranged at predetermined intervals in the conveying direction of the recording medium. Therefore, even when a solid black image is formed on the recording medium, the toner does not fly out of the toner carrier at the same time through the through holes adjacent to each other, and the penetrating holes located on the upstream side in the transport direction of the recording medium. After the toner flies through the holes, the toner flies through the adjacent through-holes when the recording medium moves downstream of the transport direction by the interval of the through-holes.

Looking at the toner carrier, the portion where the toner has flown through the through-hole arranged on the upstream side in the conveying direction of the recording medium is larger than the diameter of the through-hole, and this portion is the next through-hole. When arranged in a direction perpendicular to the transport direction with respect to the holes, an electric field for causing toner to fly to the next through-hole is formed, so that a part of the toner to pass through the next through-hole has already been formed. There is a problem that the toner does not exist, the flying amount of the toner decreases, and white streaks occur in the image in the transport direction, thereby deteriorating the image quality.

SUMMARY OF THE INVENTION An object of the present invention is to provide a direct recording type image forming apparatus capable of accurately controlling toner flight and maintaining a good image forming state without causing a significant increase in cost. To provide.

[0012]

According to the first aspect of the present invention, a flying electric field is selectively formed in a plurality of through-holes arranged in a predetermined direction, and the flying electric field is applied to the toner carried by the toner carrier. In an image forming apparatus that forms an image by flying to a recording medium via a formed through-hole, a plurality of toner carriers are arranged in parallel in a direction in which the through-hole is arranged,
A voltage controller is provided which selectively applies a potential difference between any of the plurality of control electrodes provided in the through hole and any of the plurality of toner carriers to form a flying electric field.

According to the first aspect of the present invention, it is possible to selectively connect any one of the plurality of toner carriers arranged in parallel to the direction in which the plurality of through holes are arranged and any one of the plurality of control electrodes provided in the through hole. , A flying electric field is formed in any of the plurality of through holes. Therefore, a flying electric field is selectively formed between the toner carrying member carrying the toner flying through the through hole and the through hole,
The flying electric field is accurately formed only in the through hole through which the toner passes, and the toner does not fly through the through hole adjacent to the through hole through which the toner should pass and through which the toner should not pass.

According to a second aspect of the present invention, a plurality of the through holes are arranged in each of two directions crossing each other,
It is characterized in that the same number of toner carriers as the number of arranged through holes in any one of the two directions are arranged in this direction.

According to the second aspect of the present invention, the same number of toner carriers as the number of through holes are arranged in one of the two directions in which the through holes intersect each other. Therefore, by appropriately selecting the toner carrier that should give a potential difference between the plurality of toner carriers and the control electrode, only one of the plurality of through holes arranged in the parallel direction of the toner carrier is provided. The toner flies.

According to a third aspect of the present invention, a plurality of control electrode sets are formed by control electrodes involved in the formation of a flying electric field in the through holes that are not adjacent to each other in the one direction. A plurality of toner carriers whose number is equal to the total number of through holes in the one direction are arranged in parallel in the one direction, and the voltage control unit is provided between any one of the plurality of control electrode sets and any one of the plurality of toner carriers. In which a flying electric field is formed by selectively giving a potential difference.

According to the third aspect of the present invention, the number of control electrode sets corresponding to through holes that are not adjacent to each other in any one of two directions intersecting each other, and the number of toner carrying members arranged in parallel in that direction. Is made equal to the total number of through holes arranged in that direction. For example, when four through-holes are arranged in the parallel direction of the toner carrier and two control electrode sets related to formation of a flying electric field in two through-holes that are not adjacent to each other are configured, Two toner carriers are arranged in parallel. Therefore, the total number of toner carriers to be arranged in parallel is reduced.

According to a fourth aspect of the present invention, the voltage control section includes the plurality of control electrodes and the plurality of toners in such an order that the through-holes in which the flying electric field is formed in the plurality of through-holes are not adjacent to each other on each toner carrier. It is characterized in that a potential at the time of forming a flying electric field is sequentially applied to the carrier.

According to the fourth aspect of the present invention, the plurality of control electrodes and the plurality of toner carriers are sequentially arranged so that the through holes in which the flying electric field is formed are not adjacent to each other. Is applied at the time of formation. Therefore, the toner does not fly continuously from a partially overlapping range in the toner carrier, and there is no shortage of toner in the image formed on the recording medium.

According to a fifth aspect of the present invention, there is provided the control electrode voltage application section, wherein the voltage control section selectively applies a potential when a flying electric field is formed or a potential when a flying electric field is not formed to each of the plurality of control electrodes. And a toner carrier voltage application section for selectively applying a potential when a flying electric field is formed or a potential when no flying electric field is formed to each of the plurality of toner carriers.

According to the fifth aspect of the present invention, a potential when a flying electric field is formed or a potential when a flying electric field is not formed is applied to each of the plurality of control electrodes from the control electrode voltage application section, and each of the plurality of toner carriers is The potential at the time of formation of the flying electric field or the potential at the time of non-formation is applied from the toner carrier voltage application unit. Therefore, the potential at the time of formation of the flying electric field is applied to the control electrode and the toner carrier where the flying electric field is to be formed, and the flying electric field is not formed to the control electrode and the toner carrier where the flying electric field should not be formed. Is applied, and a flying electric field is formed only in the through hole where the potential at the time of forming the flying electric field is applied to both the control electrode and the toner carrier, and either the control electrode or the toner carrier is The flying electric field is not formed in the through-hole to which the potential when the flying electric field is not formed is applied to both, and the potential when the flying electric field is formed is selectively formed in both the plurality of control electrodes and the plurality of toner carriers. The toner flies only through the through hole specified by the application.

[0022]

FIG. 1 is a schematic diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 10 includes a printing unit 1, a recording medium supply unit 4, a fixing unit 6, and a control unit 7. The recording medium supply unit 4 includes a recording medium storage unit 40 mounted on the upper surface of the main body of the image forming apparatus 10, a pickup roller 41 for feeding out the recording medium P stored in the recording medium storage unit 40 one by one,
The printing unit 1 prints the sent recording medium P at a predetermined timing.
A registration roller 42 for guiding the inside is provided. The pickup roller 41 and the registration roller 42 are driven via a drive mechanism (not shown) based on a drive signal output from the control unit 7.

The fixing unit 6 detects the temperature of the cylindrical heat roller 62 containing a heater 61 such as a halogen lamp therein, the pressure roller 63 that contacts the heat roller 62 at a predetermined pressure, and the temperature of the heat roller 62. Temperature sensor 64
The on / off control of the heater 61 based on the detection signal of the temperature sensor 64 maintains the surface temperature of the heat roller 62 at a temperature at which the toner can be melted. The recording medium P that has passed through the printing unit 1 is guided between the heat roller 62 and the pressure roller 63 in the fixing unit 6,
Subject to heat and pressure. Thus, the toner attached to the surface of the recording medium P is melted and fixed on the surface of the recording medium P.

FIG. 2 is a diagram showing a configuration of a printing unit of the image forming apparatus. The printing unit 1 of the image forming apparatus 10 controls a toner charger 3 that supplies a predetermined amount of toner T charged with a charge of a predetermined polarity and a predetermined value, and controls flying of the toner supplied by the toner charger 3. A flight control unit 2 and a counter electrode 11 facing the flight control unit 2 with a certain gap therebetween are provided. The toner charger 3, the flight control unit 2, and the counter electrode 11 are arranged in this order from below. Therefore, in the printing unit 1, the toner flies upward from below.

FIG. 3 is a diagram showing a configuration of a toner charger constituting a printing unit of the image forming apparatus. The toner charger 3 includes a toner carrier storage tank 36 in which four toner carriers 45 to 48, four supply rollers 53 to 56, and four regulating members 49 to 52 are arranged together with two supply members 57.
A toner storage tank 39 in which the stirring roller 37 is disposed,
It is constituted by. In the toner storage tank 39, the stirring roller 37 is driven to rotate in a predetermined direction, and stirs the toner stored in the toner storage tank 39.

In the toner carrier storage tank 36, each of the supply rollers 53 to 56 comes into contact with each of the toner carriers 45 to 48 arranged in parallel with each other.
Each of the regulating members 49 to 52 abuts. The supply rollers 53 to 56 supply the toner to the peripheral surfaces of the toner carriers 45 to 48. Each of the toner carrying members 45 to 48 is disposed in a small chamber separated by regulating members 49 to 51 and a partition so that the toner applies an appropriate powder pressure to each of the regulating members 49 to 52. Have been.

The toner carriers 45 to 48 are made of, for example, a metal material such as aluminum, a rubber material such as urethane, silicon or ethylene propylene, or a material obtained by adding a conductive agent such as carbon black or ion to these rubber materials. It is formed as a material and rotates at a peripheral speed of, for example, 60 mm / sec. Irregularities of several μm to several tens μm are uniformly formed on the surface of each of the toner carriers 45 to 48, and the toner is formed on the surfaces of the toner carriers 45 to 48 by the regulating members 49 to 52, respectively. A predetermined charge is applied by frictional charging, the thickness of the toner layer on the surface of the toner carriers 45 to 48 is regulated to a predetermined value, and the toner carriers 45 to 48 are conveyed to the print area by rotation. Is done.

The regulating members 49 to 52 are made of a metal such as stainless steel, phosphor bronze or nickel-coated iron, a rubber material such as urethane, silicon or ethylene propylene, or a conductive agent such as carbon black or ion. It is formed into a rigid body or an elastic body by using the added material as a material.

The supply rollers 53 to 56 are formed of a material obtained by adding a conductive agent such as carbon black to urethane, and have a foamed surface in order to increase the supply efficiency of the toner. Each of the supply rollers 53 to 56 is
It rotates at the same peripheral speed in the same direction as the toner carriers 45 to 48.

As the toner, a non-magnetic one-component toner in which a colorant, a charge controlling agent and a release agent are added to a main resin such as styrene acrylic or polyester and an external additive such as silica or titania is added, or Further, a magnetic toner to which magnetic powder is added can be used.

The surface roughness of the toner carriers 45 to 48, the linear pressure of the regulating members 49 to 52, and the materials of these members depend on the charge amount, transport amount and layer thickness required for the toner. It is determined.

FIG. 4 is a plan view and a sectional view of a flight control unit constituting a printing unit of the image forming apparatus. The flight control unit 2 is disposed on the upper surfaces of the toner carriers 45 to 48 and controls the flight of toner adsorbed and conveyed on the peripheral surfaces of the toner carriers 45 to 48. The flight control unit 2 includes a cover layer 27
After forming the control electrode 23 thereon, the cover layer 2
7, and a polyimide resin can be used as the cover layer 27. This flight control unit 2
Is formed by forming four rows of four through holes 22 linearly arranged in a direction inclined by a predetermined angle with respect to the transport direction of the recording medium and forming a plurality of rows in a direction orthogonal to the transport direction of the recording medium. is there. The control electrodes 23 are formed in a ring shape at the edge of each through-hole 22, and are connected by a strip-shaped electrode 24 for each column. Each of the through holes 22 is formed to have an opening diameter of, for example, 160 μm, and the opening diameter is increased on the lower surface facing the toner carriers 45 to 48. The control electrode 23 and the strip electrode 24 can be made of, for example, a copper foil having a thickness of about 18 μm.

Incidentally, a shield electrode may be formed on the upper surface of the control electrode 23 via the cover layer 27.

FIG. 5 is a diagram showing a circuit configuration of a printing unit of the image forming apparatus. The control electrode 23 is connected to a control electrode voltage application circuit 72 via a strip electrode 24 serving as a power supply electrode. The control electrode 23 is applied with a rectangular wave voltage corresponding to the image information from the control electrode voltage application circuit 72.
When the toner carried on the toner carrying members 45 to 48 is caused to fly to the counter electrode 11 side through the through hole 22 of the flight control unit 2, an ON potential of, for example, +300 V is applied to the control electrode 23 to cause the toner to fly. Is prevented when the control electrode 23
For example, an off potential of 0 V is applied.

On the other hand, each of the toner carriers 45 to 48 is connected to a toner carrier voltage application circuit 73.
A rectangular wave voltage corresponding to the image information is applied from the toner carrier voltage application circuit 73 to each of the toner carriers 45 to 48. When the toner carried on the toner carriers 45 to 48 is caused to fly to the counter electrode 11 side through the through hole 22 of the flight control unit 2, an ON potential of, for example, 0 V is applied to the control electrode 23 to cause the toner to fly. Is applied, an off-potential of, for example, +300 V is applied to the control electrode 23.

In the flight controller 2, the control electrode 23 is fixed to the electrode mount 21 so as to face the toner carriers 45 to 48, and is arranged so as to be parallel to the counter electrode 11. The counter electrode 11 is formed of a toner carrier 45-48.
Are arranged so that the distance from the outer peripheral surface thereof is, for example, 1 mm, and a voltage of, for example, 2 kV is applied from the counter electrode voltage application circuit 71 during a printing operation. In the electric field between the counter electrode 11 and the toner carriers 45 to 48, the flying toner does not adhere to the flying control unit 2, and the flying trajectory of the toner passing through the through-hole 22 does not expand. It is required that scattering of the attached toner can be prevented. On the other hand, the interval between the outer peripheral surfaces of the toner carriers 45 to 48 and the control electrode 23 is set to, for example, 100 μm, and is smaller than the inner diameter of the ring-shaped control electrode 23. As a result, the influence of the electric field generated by applying a voltage to the control electrode 23 is reduced.
Of the toner carrier 45
To 48 can reliably fly the toner.

In the above configuration, the voltage corresponding to the image information is applied to the control electrode 23 by the control electrode voltage application circuit 72, and the voltage corresponding to the image information is applied to the toner carrier 45 to 45 by the toner carrier voltage application circuit 73. When the voltage is applied to the toner carrier 48, the electric field acting on the toner layer on the surface of the toner carrier 45 to 48 changes, and the flying of the toner from the surface of the toner carrier 45 to 48 is controlled. The controller unit 7
A main control unit that controls the entire image forming apparatus 10 together with a control electrode voltage application circuit 72 and a counter electrode voltage application circuit 71, an image processing unit that converts obtained image information into image data to be printed, And an image forming control unit 8 for converting the image data obtained from the image processing unit into image data to be given to the flight control unit 2.

The control electrode voltage application circuit 72 and the toner carrier voltage application circuit 73 are made up of two FETs having different polarities arranged in a push-pull manner. The voltage applied to the control electrode 23 is switched, and the rise and fall of the voltage change at the time of voltage switching are made steep, so that the switching can be speeded up. Pixel quality can be improved with high accuracy.

The image forming apparatus 10 configured as described above
Will be described below. When an image signal is transmitted from an external device such as a host computer to the controller unit 7, the controller unit 7 separates the image signal into a print start signal, a control signal such as a recording medium size, and image information, and outputs the image signal according to the print start signal. By rotating the pickup roller 41, the recording medium P stored in the recording medium storage unit 40 is sent out to a position where the recording medium P comes into contact with the registration roller 42. At this time, the rotation of the pickup roller 41 is started after confirming that the recording medium P is present by the sensor provided in the recording medium storage unit 40 for detecting the presence or absence of the recording medium P. Next, the registration roller 42 rotates at a constant speed,
The recording medium P is conveyed into the printing unit 1 while being pressed by the recording medium guide plate 43 at a constant speed. In synchronization with the rotation of the registration roller 42, processing of image information is started in the image forming control unit of the controller unit 7. Since the recording medium P is conveyed from a state in which it is in contact with the registration roller 42, printing is started from a predetermined position calculated in the image forming control unit.

In the printing section 1, the toner uniformly stirred by the stirring roller 37 in the toner charger 3 is supplied to the toner carrier storage tank 36, and is fed into the small chamber by the supply rollers 53 to 56. It is. The toner sent into the small chamber is pressed and rubbed by the toner carrying members 45 to 48 and the regulating members 49 to 52 to be charged to a predetermined polarity, adheres to the surface of the toner carrying members 45 to 48, and Flight control unit 2 by rotation of bodies 45 to 48
Is conveyed to a position facing the through-hole 22. Here, when an ON potential according to the image information is applied to the control electrode 23, a voltage difference is generated between the toner carriers 45 to 48 and the control electrode 23, and the toner layer on the surface of the toner carriers 45 to 48 is formed. A potential distribution which is convex with respect to the toner carriers 45 to 48 is formed on the counter electrode 11 via the through holes 23 from the surface of the toner carriers 45 to 48 in accordance with the electric field strength in the toner layer. Adhere to the surface of the recording medium P that is in contact with the recording medium P. The recording medium P that has passed through the printing unit 1 is guided to the fixing unit 6 and receives heat and pressure. FIG. 6 is a diagram showing a timing chart showing printing timings on the toner carrier and the control electrodes in the image forming apparatus and a diagram showing printing conditions. As shown in FIG. 6B, when a negatively charged toner is used as the toner, 0 V is applied to the toner carriers 45 to 48.
Is applied, and when +300 V is applied to the control electrode 23, printing by flying toner is performed. That is, 0 V or +300 is applied to both the toner carriers 45 to 48 and the control electrode 23.
When a voltage of V is applied, there is no potential difference between the toner carriers 45 to 48 and the control electrode 23, so that printing by flying toner is not performed. Further, the toner carriers 45 to 4
8 when +300 V is applied to the control electrode 23 and 0 V is applied to the control electrode 23, an electric field in the opposite direction from the control electrode 23 to the toner carriers 45 to 48 is formed. I can't.

As shown in FIG. 6A, the toner carrier 4
A voltage of +300 V during non-printing and 0 V during printing is applied to 5-48. That is, the toner carriers 45 to 48 have
A square wave print signal having a voltage of 0 V is sequentially supplied in synchronization with the print timing. On the other hand, a voltage of +300 V is applied to the control electrode 23 during printing and 0 V during non-printing. For example, a voltage of 0 V is applied to the first toner carrier 45, and +300 is applied to the other toner carriers 46 to 48.
When a voltage of V is applied and a voltage of +300 V is applied to the control electrode 23, printing by flying toner is performed through the through hole 22 in the control electrode 23 facing the surface of the first toner carrier 45. And other toner carriers 46 to 48
No printing by flying toner is performed through the through hole 22 in the control electrode 23 facing the surface of the toner.

Next, a voltage of 0 V is applied to the second toner carrier 46, and the other toner carriers 45, 4
When a voltage of +300 V is applied to 7, 48 and a voltage of +300 V is applied to the control electrode 23, the second toner carrier 4
6, the printing is performed by the flying of the toner through the through-hole 22 in the control electrode 23 facing the surface of the control electrode 23, and the control electrode 2 facing the surfaces of the other toner carriers 45, 47 and 48.
No printing is performed by the flying of the toner through the through hole 22 in 3.

The same applies to the case where a voltage of 0 V is applied only to the third toner carrier 47 and the case where a voltage of 0 V is applied to only the fourth toner carrier.

As described above, +30 is applied to the control electrode 23.
When the voltage of 0V is applied, the toner carrier 45
By selectively applying a voltage of 0 V to 48 in order,
A dot of an arbitrary pixel on the surface of the recording medium P can be formed by toner flying through any one of the four through holes 22 arranged in the transport direction of the recording medium.

FIG. 7 is a plan view and a sectional view of a flight control unit of an image forming apparatus according to a second embodiment of the present invention.
FIGS. 7B to 7E show cross sections at respective positions of L, M, N, and O in FIG. 7A. As shown in FIG. 7A, the flight control unit 2 of the image forming apparatus according to the present embodiment provides a predetermined inclination angle with respect to the conveyance direction of the recording medium P, and the four flight control units are arranged obliquely. A first control electrode 29 and a second control electrode 30 each having a ring shape are arranged at each edge of the hole 34, and a voltage corresponding to image information is applied to the first control electrode 29 and the second control electrode 29. To the control electrode 30 of
The through holes 34 are electrically opened and closed to open the toner carriers 45 to 48.
The printing is performed by controlling the flying of the toner from the surface.

As shown in FIGS. 7B to 7E, the flight control section 2 arranges a first control electrode 29 and a second control electrode 30 with an insulating layer 28 interposed therebetween. The cover layer 27 is formed on both sides. The cover layer 27 and the insulating layer 28 are formed with a thickness of about 25 μm using, for example, a polyimide resin as a material. First control electrode 29
The second control electrode 30 is made of, for example, a copper foil having a thickness of about 18 μm, and has an inner diameter of 230 μm or 350 μm.
m and an outer diameter of 330 μm or 450 μm.
Each of the 60 μm through holes 34 is formed in a double concentric shape.

In the four through-holes 34 forming one row of through-holes, the first control electrode 29 is located in the first and third through-holes 34 from the upstream side in the transport direction of the recording medium P. The second control electrode 30 is located inside and
Of the first control electrode 29 in the second and fourth through holes 34 from the upstream side in the transport direction of the recording medium.
Located inside. In each through-hole row, the four first control electrodes 29 are connected by a band-shaped power supply electrode 31, and the four second control electrodes 30 are connected by a band-shaped power supply electrode 32.

Two toner carriers 58 and 59 are arranged in the toner charger 3 so as to face the flight controller 2. The first toner carrier 58 disposed on the upstream side in the transport direction of the recording medium in the toner charger 3 is disposed at the first and second positions in the flight control unit 2 from the upstream side in the transport direction of the recording medium. Facing the through hole 34. On the other hand, the second toner carrier 59 disposed in the toner charger 3 on the downstream side in the transport direction of the recording medium is located at the third and fourth positions in the flight controller 2 from the upstream side in the transport direction of the recording medium. Opposes the through-hole 34 arranged at

As shown in FIG. 8, a flat shield electrode 35 is provided on the toner carrier 58, 59 side of the flight controller 2.
May be arranged. This shield electrode 35 is, for example,
A hole 35 is formed at a position corresponding to each of the through holes 34 of the flight control unit 2 by stacking titanium to a thickness of about 1 μm.
a is formed. The opening diameter of the hole 35a is larger than the outer diameter of the control electrode located inside in each through hole 34, and smaller than the inner diameter of the control electrode located outside.

In the flight control unit 2 configured as described above, the first control electrode 29 and the second control electrode 30 located at the edge of the through hole 34 through which the toner passes are located more inside. By applying a voltage at the time of printing to the control electrode, the toner carried by the toner carrier 58 or 59 is caused to fly through a desired through-hole 34, thereby performing printing on the surface of the recording medium.

FIG. 9 is a timing chart of voltages applied to the toner carrier and the control electrodes in the image forming apparatus. The toner carriers 58 and 59 have +
A printing signal for applying a voltage of 300 V and applying a voltage of 0 V during printing is supplied. That is, the toner carriers 58 and 59
, A rectangular wave print signal having a voltage of 0 V is sequentially supplied in synchronization with the print timing. On the other hand, the control electrodes 29, 3
To 0, a voltage of +300 V is applied during printing and a voltage of 0 V is applied during non-printing.

For example, a voltage of 0 V is applied to the first toner carrier 58 and a positive voltage is applied to the second toner carrier 59.
A voltage of 300 V is applied, and +30 is applied to the first control electrode 29.
When a voltage of 0 V is applied and a voltage of 0 V is applied to the second control electrode 30, the control electrode 29 and the toner carrier 58 located inside the first through hole 34 from the upstream side in the transport direction of the recording medium are arranged. A potential difference is generated between the toner carrier 58 and the toner transported by the toner carrier 58 via the first through hole 34 from the upstream side in the transport direction of the recording medium. At this time, since the inner diameter of the control electrode 30 that does not cause a potential difference with the toner carrier 58 is larger than the outer diameter of the control electrode 29, the potential of the control electrode 30 affects the flying of the toner in the first through hole 34. Will not give. In the second through hole 34 from the upstream side in the transport direction of the recording medium, the inner diameter of the control electrode 29 that generates a potential difference between the control electrode 29 and the toner carrying member 58 has a potential difference between the control electrode 29 and the toner carrying member 58. Since the diameter is larger than the outer diameter of 30, the toner does not fly in the second through hole 34 due to the voltage of the control electrode 29. Further, in the third through hole 34 from the upstream side in the transport direction of the recording medium, there is no potential difference between the control electrode 29 located inside and the toner carrier 59, and in the fourth through hole 34, An electric field in the opposite direction from the control electrode 30 located inside to the toner carrier 59 is formed, and the third through-hole 34 is formed.
Also, the toner does not fly through the fourth through hole 34. Accordingly, in this case, printing is performed only by the first through hole 34 by the flying of the toner.

Next, +300 is applied to the first toner carrier 58.
V, and the second toner carrier 59
Is applied to the first control electrode 29 by + 300V.
V, and 0 V is applied to the second control electrode 30.
When a voltage of V is applied, a potential difference is generated between the control electrode 29 located inside the third through hole 34 from the upstream side in the transport direction of the recording medium and the toner carrier 59, and the potential difference is increased in the transport direction of the recording medium. Printing is performed by the flying of the toner conveyed by the toner carrier 59 through the third through hole 34 from the side. At this time, since the inner diameter of the control electrode 30 that does not generate a potential difference with the toner carrier 59 is larger than the outer diameter of the control electrode 29, the potential of the control electrode 30 affects the flying of the toner in the third through hole 34. Will not give. Further, in the fourth through hole 34 from the upstream side in the transport direction of the recording medium, the inner diameter of the control electrode 29 that generates a potential difference between the control electrode 29 and the toner carrier 59 has no potential difference with the toner carrier 59. Since the diameter is larger than the outer diameter of 30, the toner does not fly in the fourth through hole 34 due to the voltage of the control electrode 29. Further, in the first through hole 34 from the upstream side in the transport direction of the recording medium, there is no potential difference between the control electrode 29 located inside and the toner carrier 58, and the second through hole 34 An electric field in the opposite direction from the control electrode 30 located inside to the toner carrier 58 is formed, and the first through-hole 34 is formed.
Also, the toner does not fly through the second through hole 34. Therefore, in this case, printing is performed only by the third through hole 34 by the flying of the toner.

Next, a voltage of 0 V is applied to the first toner carrier 58, and +3 is applied to the second toner carrier 59.
A voltage of 00 V is applied, a voltage of 0 V is applied to the first control electrode 29, and +300 is applied to the second control electrode 30.
When a voltage of V is applied, a potential difference is generated between the control electrode 30 located inside the second through hole 34 from the upstream side in the transport direction of the recording medium and the first toner carrier 58,
Printing is performed by the toner transported by the toner carrier 58 via the second through hole 34 from the upstream side in the transport direction of the recording medium. At this time, the inner diameter of the control electrode 29 that does not cause a potential difference with the toner carrier 58 is
Since it is larger than the outer diameter of 0, the potential of the control electrode 29 does not affect the flying of the toner in the second through hole 34. Further, in the first through hole 34 from the upstream side in the conveying direction of the recording medium, the inner diameter of the control electrode 30 that generates a potential difference between the control electrode 30 and the toner carrying member 58 has no potential difference with the toner carrying member 58. Since the diameter is larger than the outer diameter of the second through hole 29, the toner does not fly in the second through hole 34 due to the voltage of the control electrode 30. Further, in the third through hole 34 from the upstream side in the conveyance direction of the recording medium, the toner carrier 5 is moved from the control electrode 29 located inside.
9, an electric field is formed in the opposite direction to the control electrode 30 and the toner carrier 5 located inside the fourth through hole 34.
No potential difference is generated between the first through-hole and the third through-hole, and the toner does not fly through the third through-hole and the fourth through-hole. Therefore, in this case, printing is performed only by the second through hole 34 by the flying of the toner.

Next, +300 is applied to the first toner carrier 58.
V, and the second toner carrier 59
, A voltage of 0 V is applied to the first control electrode 29, and +300 is applied to the second control electrode 30.
When a voltage of V is applied, a potential difference is generated between the control electrode 30 located inside the fourth through hole 34 from the upstream side in the transport direction of the recording medium and the toner carrier 59, and the potential difference is increased in the transport direction of the recording medium. Printing is performed by the flying of the toner conveyed by the toner carrier 59 via the fourth through hole 34 from the side. At this time, since the inner diameter of the control electrode 29 that does not cause a potential difference with the toner carrier 59 is larger than the outer diameter of the control electrode 30, the potential of the control electrode 29 affects the flying of the toner in the fourth through hole 34. Will not give. Further, in the third through hole 34 from the upstream side in the conveying direction of the recording medium, the inner diameter of the control electrode 30 that generates a potential difference between the control electrode 30 and the toner carrier 59 does not cause a potential difference with the toner carrier 59. Since the diameter is larger than the outer diameter of the third through hole 29, the toner does not fly in the third through hole 34 due to the voltage of the control electrode 30. Further, in the first through hole 34 from the upstream side in the transport direction of the recording medium, an electric field in the opposite direction from the control electrode 29 located inside to the toner carrier 58 is formed. No potential difference occurs between the control electrode 30 and the toner carrying member 58 located in the first through hole 34.
Also, the toner does not fly through the second through hole 34. Therefore, in this case, printing is performed only by the fourth through hole 34 by the flying of the toner.

As described above, the voltage of +300 V is selectively applied to the control electrodes 29 and 30, and the voltage of 0 V is selectively applied to the toner carrying members 58 and 59 in order, so that the recording medium can be printed. A dot of an arbitrary pixel on the surface of the recording medium P can be formed by toner flying through one of the four through holes 34 arranged in the transport direction in order.

Also, by preventing the voltage at the time of forming the flying electric field from being applied to the two through holes 34 where the toner carriers 58 and 59 face each other at a continuous timing, the surface of the toner carriers 58 and 59 is prevented. In this case, it is possible to prevent the toner from flying from the partially overlapping range, and to prevent a decrease in image quality such as the occurrence of white streaks in a solid black image due to a decrease in the amount of flying toner.

The positions of the through holes 34 in the flight control section 2 are, for example, as shown in FIG.
4 may be arranged in a staggered manner in the recording medium conveyance direction. By arranging in this manner, the toner flies from each of the toner carrier 58 and the toner carrier 59 with respect to two dots adjacent to each other in the direction orthogonal to the transport direction on the recording medium, and the surface of the toner carrier In the range including the portion where the toner has already flown, printing is not continuously performed by the flying of the toner, and the occurrence of white streaks in a solid black image due to an insufficient amount of flying toner is prevented. be able to.

The distance between the toner carriers 58 and 59 and the control electrodes 29 and 30 is smaller than the inner diameter of the control electrode located inside of the control electrodes 39 and 30, and the distance between the control electrodes 29 and 30 is small. The influence of the electric field due to the application of the voltage to the surface of the toner carrying members 58 and 59 is ensured.

Further, as shown in FIGS. 11A and 11B, the first control electrode 29 located inside at the edge of the first through hole 34 from the upstream side in the transport direction of the recording medium.
The distance d1 between the second control electrode 30 located inside the edge of the second through hole 34 and the surface of the toner carrier 58 is equal to the distance d2 between the second control electrode 30 and the surface of the toner carrier 58. This relationship is the same in the toner carrier 59. In this way, by making the distance between the inner control electrode which influences the flying control of the toner among the control electrodes 29 and 30 in the respective through holes 34 and the surface of the toner carrying members 58 and 59 constant, each of the through holes 34 becomes uniform. The flying amount of the toner passing through the hole 34 can be made constant, and the image forming state can be made uniform.

In addition, in the configuration shown in FIGS. 7 and 10, only the control electrodes located inside the control electrodes 29 and 30 formed on the edge of each through hole 34 are used to form the flying electric field of the toner. Are involved. Therefore, each through hole 3
In the configuration shown in FIGS. 7 and 10, only the control electrode 29 or 30 located inside may be formed at the edge portion 4.

[0062]

According to the first aspect of the invention, between any one of the plurality of toner carriers arranged in parallel in the arrangement direction of the plurality of through holes and any one of the plurality of control electrodes provided in the through hole. By selectively applying a potential difference and forming a flying electric field in any of the plurality of through holes, only between the toner carrier carrying the toner flying through the through hole and the through hole through which the toner should pass. The flying electric field can be formed accurately, the toner does not fly through the through holes through which the toner should not pass, the image can be prevented from being stained, and the image forming state can be maintained well. .

According to the second aspect of the present invention, the same number of toner carriers as the number of through-holes are arranged in one of two directions in which the through-holes intersect with each other. The toner carrier that should give a potential difference between the toner carrier and the control electrode is appropriately selected, and the toner is accurately fly through only one of the plurality of through holes arranged in the parallel direction of the toner carrier. Can be done.

According to the third aspect of the present invention, the number of control electrode sets corresponding to the through holes that are not adjacent to each other in any one of the two directions intersecting with each other and the number of the toner carrying members arranged in parallel in that direction. By making the value multiplied by the number equal to the total number of through holes arranged in that direction,
The total number of toner carriers to be arranged in parallel can be reduced, the structure of the apparatus can be simplified, and the cost can be reduced.

According to the fourth aspect of the invention, the plurality of control electrodes and the plurality of toner carriers are sequentially scattered so that the through holes in which the flying electric field is formed are not adjacent to each other. By applying the electric potential at the time of forming the electric field, the toner is prevented from flying continuously from the partially overlapping range on the toner carrier, and the toner formed on the recording medium may be insufficient. In addition, the generation of white streaks in a solid black image can be reliably prevented.

According to the fifth aspect of the present invention, a potential at the time of formation of a flying electric field or a potential at the time of non-formation is applied to each of the plurality of control electrodes from the control electrode voltage application section, and each of the plurality of toner carriers is By applying a potential at the time of formation of a flying electric field or a potential at the time of non-formation from the toner carrier voltage application unit to the control electrode and the toner carrier, the through-hole to which the potential at the time of the formation of the flying electric field is applied. A flying electric field is formed only in one or both of the control electrode and the toner carrier, so that a flying electric field is not formed in a through hole to which a potential when the flying electric field is not formed is applied. By selectively applying a potential at the time of forming a flying electric field to both the electrode and the plurality of toner carriers, the toner can be accurately fly only through the specified through-hole, and the image It can be accurately reproduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a printing unit of the image forming apparatus.

FIG. 3 is a diagram illustrating a configuration of a toner charger constituting a printing unit of the image forming apparatus.

FIG. 4 is a plan view and a cross-sectional view of a flight control unit constituting a printing unit of the image forming apparatus.

FIG. 5 is a diagram illustrating a circuit configuration of a printing unit of the image forming apparatus.

FIG. 6 is a diagram showing a timing chart and a printing condition showing a printing timing in a toner carrier and a control electrode in the image forming apparatus.

FIG. 7 is a plan view and a cross-sectional view of a flight control unit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view of a flight control unit according to another configuration of the image forming apparatus.

FIG. 9 is a timing chart of voltages applied to a toner carrier and a control electrode in the image forming apparatus.

FIG. 10 is a plan view of a flight control unit according to still another configuration in the image forming apparatus.

FIG. 11 is a diagram illustrating a positional relationship between a control electrode and a toner carrier in a printing unit of the image forming apparatus according to the second embodiment.

FIG. 12 is a diagram illustrating a configuration of a main part of a conventional image forming apparatus.

[Explanation of symbols]

 1-Printing section 2-Flying control section 3-Toner charger 4-Recording medium accommodating section 22,34-Through hole 23,29,30-Control electrode 45-48,58,59-Toner carrier 72-Control electrode voltage Application circuit 73-toner carrier voltage application circuit

Continued on the front page (72) Inventor Yukito Nishio 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation

Claims (5)

[Claims] A flying electric field is selectively formed in a plurality of through holes arranged in a predetermined direction, and a toner carried by a toner carrier is caused to fly to a recording medium via the through hole in which the flying electric field is formed. In the image forming apparatus that forms an image by performing the image forming process, a plurality of toner carriers are provided in parallel in a direction in which the through holes are arranged, and any one of the plurality of control electrodes provided in the through holes and any of the plurality of toner carriers are provided. An image forming apparatus, comprising: a voltage control section for selectively providing a potential difference therebetween to form a flying electric field. 2. A plurality of said through holes are arranged in each of two directions intersecting each other, and the same number of toner carriers as the number of through holes arranged in one of the two directions are arranged in this direction. 2. The image forming apparatus according to 1. 3. A plurality of control electrode sets are constituted by control electrodes involved in the formation of a flying electric field in through holes that are not adjacent to each other in the one direction, and the product of the control electrode sets and the number of control electrode sets is such that A plurality of toner carriers of the same number as the arrangement number of holes are arranged in parallel in the one direction, and the voltage control unit selectively causes a potential difference between any one of the plurality of control electrode sets and any one of the plurality of toner carriers. The image forming apparatus according to claim 2, wherein the image forming apparatus forms the flying electric field by applying the electric field. 4. The method according to claim 1, wherein the voltage control section sequentially controls the plurality of control electrodes and the plurality of toner carriers in such a manner that the through-holes in which the flying electric field is formed in the plurality of through-holes are not adjacent to each other. 4. An electric potential at the time of formation is applied.
An image forming apparatus according to claim 1. 5. A control electrode voltage application section for selectively applying a potential when a flying electric field is formed or a potential when a flying electric field is not formed to each of a plurality of control electrodes; A toner carrier voltage applying unit that selectively applies a potential when a flying electric field is formed or a potential when not formed,
The image forming apparatus according to claim 1, further comprising: