JPH11320952A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a high quality image without generating crosstalk of adjacent electrodes by providing an intermediate electrode between an image developing particle carrier body and an opposing electrode even when a plurality of control electrodes included in each are independently controlled. SOLUTION: This image forming apparatus comprises a toner carrier 19, an opposing electrode 21 wherein a plurality of control electrodes are arranged in one direction at a portion opposite the toner carrier body 19, a control grid 23 wherein a plurality of control electrode are arranged between the toner carrier body 19, opposing electrode 21 in a direction different from the arrangement of the opposing electrode 21 and gates 21 are formed on the positions each being superposed with each control electrode in the opposing direction, and an electrode voltage controlling means 36 for controlling the flying of the toner in accordance with an image forming signal. In the opposing electrode 21, at least an adjacent face and a face at a side of the control grid are covered with an insulation layer.

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 or a facsimile machine, or a digital printer. The present invention causes flying of visualized particles to adhere to a recording medium and flying of the visualized particles. And an image forming apparatus for forming an image directly on a recording medium by controlling the image forming apparatus based on an image signal.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method, a photoreceptor for forming an electrostatic latent image is required, and there has been a problem that the apparatus becomes large. In order to solve this problem, Japanese Patent Publication No. Hei 6-30901 and Japanese Patent Laid-Open Publication No. Hei 4-21970 disclose a method of opening and closing a passage through which toner, which is a visualized particle, passes by an electric field in an electrode matrix. Discloses a method and an apparatus for forming an image with toner.

(1) In Japanese Patent Publication No. 6-30901,
As shown in FIG. 10, the image forming apparatus combines two sets of electrode layers 104 and 105 composed of a plurality of wires arranged in parallel at regular intervals in a state where the wires are orthogonal to each other, and vertically combines them. It is disposed between the toner carrier 101 and a sheet 103 serving as a recording medium.
The counter electrode 106 is disposed below the third electrode 3. The toner carrier 101 magnetically adsorbs the magnetic toner 102 on the peripheral surface, and changes the voltage applied to the wires constituting the electrode layers 104 and 105 so that the toner carrier 101 and the opposing electrode 1 are changed.
06 and an electrostatic field is selectively formed. By moving the magnetic toner 102 through the electrode layers 104 and 105 from the toner carrier 101 to the counter electrode 106 side by the electrostatic field, the magnetic toner 102 is adsorbed on the paper 103 to form an image.

(2) In Japanese Patent Application Laid-Open No. Hei 4-21970, an image forming apparatus is arranged so as to face a toner carrier 19 as shown in FIG. 3, and a plurality of control electrodes are juxtaposed in one direction. An electrode 21, a control grid 23 disposed between the electrodes 21 and a plurality of control electrodes arranged in a direction different from the arrangement of the counter electrodes, and a counter direction between the counter electrode 21 and each control electrode of the control grid 23. And a print head 22 having an opening for forming a gate 26 serving as a passage portion of the toner 17 at a position where the print head 22 passes. Matrix driving is performed between the counter electrode 21 and the control grid 23 by using an electrode potential control means, and the electric field existing between the toner carrier 19 and the counter electrode 21 is changed, so that the toner can fly stably. The control is performed to form an image on the sheet 5.

[0005]

However, the above image forming apparatus still has the following problems.

In (1), the potential relationship between the toner carrier 101 and the counter electrode 106 is always in the toner flying direction,
In addition, a potential for causing toner to fly is applied to one electrode layer 104 (105), while the other electrode layer 105 (10
Since 4) is given a potential to suppress the toner from flying,
The behavior of the toner becomes very unstable, and there are cases where the flight of the toner cannot be suppressed. This can be improved by setting the absolute value of the toner flying suppression potential to a large value. However, the potential difference between the electrode layers 104 and 105, that is, the electric field strength, depends on the dielectric breakdown strength between the electrode layers 104 and 105. Must be: Further, since it is necessary to control the high voltage, the load on the power supply circuit unit increases, so that it is not a fundamental solution.

In (2), since the electrode control is performed separately by dividing the opposing electrode 21, the influence of the adjacent electrode in the opposing electrode on the electric field distribution on the paper surface, that is, crosstalk occurs, and the print quality is reduced. May deteriorate.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide an intermediate electrode between a visualized particle carrier and a counter electrode, and to provide the counter electrode and the intermediate electrode. To provide an image forming apparatus capable of realizing high-quality image formation with stable print quality without causing crosstalk to adjacent electrodes even when individually controlling a plurality of control electrodes included in the image forming apparatus. It is.

[0009]

According to a first aspect of the present invention, there is provided an image forming apparatus, comprising: a visualized particle carrier; and a plurality of control electrodes disposed so as to face the visualized particle carrier. Counter electrodes arranged side by side in the direction, disposed between the visualized particle carrier and the counter electrode, and a plurality of control electrodes are arranged in a direction different from the arrangement of the control electrodes of the counter electrode, A control grid in which a gate is formed at a position overlapping with each control electrode of the counter electrode in the counter direction, and flying control of the visualized particles from the visualized particle carrier to the counter electrode through the gate in accordance with an image forming signal And an electrode potential control means for forming an image by being attached to a recording medium, wherein the counter electrode has at least an adjacent surface of the plurality of control electrodes and a surface on the control grid side insulated. Sealed in layers And wherein the Rukoto.

According to a second aspect of the present invention, there is provided the image forming apparatus according to the first aspect, wherein the insulating layer comprises:
The thickness of the layer is 200 μm or less, and the control electrode width of the counter electrode sealed in the layer is at least half the pitch between the control electrodes.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be described below with reference to the drawings and tables.

(First Embodiment) A basic principle of an image forming apparatus according to the present invention and a first embodiment will be described with reference to FIGS.

As shown in FIG. 1, the image forming apparatus in this embodiment is a toner supply means for supplying toner 17 as visualized particles to a visualized particle carrier 19 (hereinafter referred to as toner carrier 19). (Toner supply unit) 2 and toner carrier 1
And an image forming unit 1 having a printing unit (printing unit) 3 for causing the toner 17 of No. 9 to fly on the recording medium 5 (hereinafter, paper 5) using electrostatic force. This image forming means 1
Is to visualize an image corresponding to the image signal on the paper 5 using the toner 17.

The toner supply means 2 accommodates the toner 17 in the toner accommodation tank 16 and stirs the toner 17 to charge the toner 17. The toner supply means 2 carries the toner 17 by electric force or magnetic force, or both. A cylindrical toner carrier 19 is provided. The thickness of the toner layer carried on the outer peripheral surface of the toner carrier 19 is determined by the doctor blade 2 provided in the toner storage tank 16.
Regulated at 0.

The printing means 3 includes a counter electrode control means 15 facing the outer peripheral surface of the toner carrier 19, and a print head 22 provided between the counter electrode control means 15 and the toner carrier 19. I have. The counter electrode control means 15 includes the counter electrode 21 and a power supply means 29 based on an image forming signal sent from the print control means 36.
Controls the voltage supplied to the opposing electrode 21 from the. This control signal is referred to as a counter electrode control signal. Print head 22
Includes a grid electrode 23 and controls a voltage supplied from the power supply unit 29 to the grid electrode 23 based on an image forming signal supplied from the print control unit 36. This control signal is referred to as a grid electrode control signal.

The configuration of the counter electrode 21 and the grid electrode 23 in the printing means 3 will be described with reference to FIG.

The counter electrode 21 is a flat plate provided parallel to the tangential direction of the toner carrier 19 or the toner carrier 1.
The paper 5 in the printing means 3 is placed on an arc-shaped or cylindrical insulating material (not shown) provided in parallel with the paper 9.
Plate-like control electrode 42 elongated in the X direction
(Hereinafter referred to as the opposing control electrodes 42) are formed in parallel with each other.

The grid electrode 23 is a plate-shaped control electrode 51 (hereinafter, referred to as a grid control electrode 51) which is parallel to the counter electrode 21 and is elongated in the Y direction which is a direction intersecting the counter control electrode 42 of the counter electrode 21. A plurality of them are formed side by side in parallel. The grid control electrode 51 has a circular opening 51a for forming the gate 26 in the longitudinal direction.
Is formed, and the toner flow from the toner carrier 19 toward the counter electrode 21 can pass therethrough.

The paper 5 which has been conveyed to the position of the printing means 3 to visualize the toner 17 is moved by the recording medium guide means (not shown) at the position of the printing means 3 to the opposite electrode 21, It is assumed that the positional relationship with the print head 22 (actually, the grid electrode 23) is fixed.

Next, the principle of image formation by the image forming means 1 will be described.

Generally, when the charged particles are placed on the air (vacuum) material interface, an attractive force is generated between the material interface and the charged particles due to the electrostatic force. This is a well-known fact electromagnetically. Therefore, the toner 17 is
9 is supported by electrostatic force on the surface thereof. In this state,
The toner 17 and the toner carrier 19 are provided on the surface of the toner carrier 19.
When an electric field exceeding the electromagnetic attraction force is applied between
The toner 17 is separated from the toner carrier 19, accelerated by the force of the electric field, and moves in a specific direction. Therefore, an electric field capable of causing the toner 17 carried on the toner carrier 19 to fly to the counter electrode 21 is generated by the relationship between the potential applied to the grid electrode 23 and the potential relationship between the toner carrier 19 and the counter electrode 21. 19 on the surface.

As a result, as shown in FIG. 3, the electric field causes the toner 17 to pass through the grid electrode 23 and fly to the counter electrode 21. In this case, when the potential applied to the counter electrode 21 and the grid electrode 23 is controlled according to the image signal, and the paper 5 is arranged on the side of the counter electrode 21 facing the toner carrier 19, the image signal is applied to the surface of the paper 5. Is formed in accordance with. The electric field at which the toner 17 starts to fly is referred to as a toner-flying start electric field Eth, and generally has a value of 1.0 M (V / m).

Next, a control method in the case of causing toner to fly will be described.

The potential applied to the opposing control electrode 42 of the opposing electrode 21 is the toner flying potential Vb1 and the toner flying suppression potential V
b2, the potential applied to the grid control electrode 51 of the grid electrode 23 is defined as a toner flying potential Vg1 and a toner flying suppression potential Vg2. At this time, the combinations of potentials applied to the gates 26 are (Vb1, Vg1), (Vb1).
1, Vg2), (Vb2, Vg1), (Vb2, Vg
There are four types of 2). Of this combination, (Vb1,
Vg1) is a potential at which both control electrodes 42 and 51 cause the toner 17 to fly, and the toner 17 flies through this gate 26. On the other hand, in the remaining three combinations, since the potential for suppressing the flying of the toner 17 is given to at least one of the control electrodes, the toner 17 cannot fly.

The above combination will be described in more detail.

(A) A potential at which the electric field between the toner carrier 19 and the counter electrode 21 becomes an electric field Eb (Eth> Eb) weaker than the toner flying start electric field Eth is given as the toner flying potential Vb1 of the counter control electrode 42. In this case, the electric field Eg between the toner carrier 19 formed by the toner flying potential Vg1 of the grid control electrode 51 and the counter electrode 21 is | Eth-E
By setting b | or more, the toner 17 can fly in the combination of (Vb1, Vg1).

Next, since the electric field between the toner carrier 19 and the counter electrode 21 formed by the toner jump suppressing potential Vb2 of the counter control electrode 42 is in the direction of suppressing the toner jump, (Vb2, Vg1) In the combination of (Vb2, Vg2), the toner 17 cannot fly, and even if there is the toner 17 flying due to the electric field formed by the toner flying potential Vg1 of the grid control electrode 51, especially in the vicinity of the sheet 5, the electric field for suppressing the flying is present. Due to the high strength, the toner 17 does not adhere to the paper 5.

In the remaining combinations (Vb1, Vg2),
Since the electric field between the toner carrier 19 and the counter electrode 21 formed by the toner flight suppression potential Vg2 of the grid control electrode 51 is in the direction of suppressing the toner flight, the toner 17 cannot fly from the toner carrier 19. No leakage occurs. In particular, the grid control electrode 5 is set so that the electric field in the vicinity of the toner carrier 19 in the above combination becomes an electric field in the flight suppression direction.
By setting the toner flying suppression potential Vg2 of 1, the leakage of the toner 17 at the time of flying suppression can be eliminated.

In addition, the toner flying suppression potential Vb2 of the opposing control electrode 42 is different from the opposing control electrode 42 and the grid control electrode 5
If the absolute value of the potential is higher, the controllability is improved and the leakage of the toner 17 can be eliminated as long as the dielectric breakdown does not occur between the electrodes 1 and between the adjacent electrodes of the opposing control electrode 42. But,
Since the driving voltage of the opposing electrode control means 15 is high and the load becomes large, the electric field intensity for suppressing the flight formed by the opposing control electrode 42 has an absolute value less than the electric field intensity for the flying formed by the opposing control electrode 42. It is desirable that
Conversely, in order to simplify the configuration of the control system, the counter control electrode 4
The toner flying suppression potential Vb2 of No. 2 may be 0 V, but the controllability is slightly inferior. Therefore, preferably, when the applied voltage of the grid control electrode 51 is equal to or more than the absolute value of the applied voltage at the time of toner flying suppression, an electric field in the flying direction is not generated at the time of toner flying suppression, and stable flying of the toner 17 can be suppressed.

Similarly, the toner flying suppression potential Vg2 of the grid control electrode 51 is within the absolute value of the potential as long as the dielectric breakdown does not occur between the opposing control electrode 42 and the grid control electrode 51 and between adjacent electrodes of the grid control electrode 51. Is higher, the controllability is improved and the leakage of the toner 17 can be eliminated.
However, the driving voltage of the print head 22 is high, and the burden increases. Conversely, in order to simplify the configuration of the control system, the toner flying suppression potential Vg2 of the grid control electrode 51 may be set to 0 V, but the controllability is slightly inferior.

(B) As another combination, the toner carrier 1
9 and the opposing electrode 21 are the toner flying start electric field E
A potential at which an electric field Eb ′ (Eth <Eb ′) stronger than th may be given as the toner flying potential Vb1 of the counter control electrode 42. In this case, the toner flying potential Vg1 of the grid control electrode 51 may be 0 V.
When the potential is set so as to form an electric field that assists flight of 7, the controllability at the time of printing is further improved.

(Vb2, Vg1), (Vb2, Vg2)
In the combination of (1), the toner 17 cannot fly as in the case of (A). Even if the flying toner 17 exists, the toner 17 does not adhere to the paper 5 in the vicinity of the paper 5 because the electric field strength of the flying suppression is particularly high.

The flying suppression electric field Eg 'between the toner carrier 19 and the counter electrode 21 formed by the toner flying suppression potential Vg2 of the grid control electrode 51 is | Eb'-Eth |
By setting a larger value, the toner 17 cannot fly in the combination of (Vb1, Vg2). In particular, by setting the toner flight suppression potential Vg2 of the grid control electrode 51 so that the electric field in the vicinity of the toner carrier 19 in this combination becomes a field in the flight suppression direction, leakage of the toner 17 during flight suppression is eliminated. can do.

In addition to the above, when the potential difference in the toner flying direction of the control grid 23 at the time of flying toner is increased, the amount of toner collected on the control grid 23 increases, and the toner 17 adhered to the control grid 23 causes clogging. May occur. For this reason, it is desirable that the potential is at least lower than the absolute value of the potential of the opposing control electrode 42 when the toner flies. More preferably, the electric field strength in the toner flying direction formed by the grid control electrode 51 is
As long as the electric field strength is smaller than the electric field strength in the toner flight direction formed by the toner 2, the toner 17 can be efficiently discharged in the paper direction.

In the control of the grid control electrode 51, if an electric field for suppressing the flying of the toner is formed in all the grid control electrodes 51 for an arbitrary time before the potential of the opposing control electrode 42 is switched, the electric current passes through the control grid 23. Thus, the potential of the opposing control electrode 42 is switched before adhering to the paper 5, and it is possible to prevent the toner from adhering to the surface of the control grid 23 opposing the paper recording surface, thereby preventing contamination due to contact with the paper.

FIG. 4 is a diagram showing a configuration in which the toner 17 flies only at the gate _Gmn as matrix control based on the above contents.

[0037] The counter electrode control unit 41 and the driver 39 of the high-voltage driver section 38 on the basis of the signal of the grid electrode control unit 40, the control electrode X _m of the counter electrode 21, to the control electrode Y _n of the grid electrode 23, respectively Vb1, While applying Vg1, Vb2 and Vg2 are applied to the other opposing control electrode 42 and grid control electrode 51, respectively.

[0038] _{X m + i = Vb2 Y n} + i = Vg2 (i = 1,2) X m = Vb1 Y n = Vg1 X mi = Vb2 Y ni = Vg2 (i = 1,2) result, each of the control The potentials applied to the electrodes 42 and 51 and ON / ○ FF of each gate 26 are as shown in Table 1 below.

[0039]

[Table 1]

Based on the above basic principle and the toner flying method, the positional relationship between the counter electrode control means 15 and the print head 22 in the printing means 3 of the image forming means 1 in this embodiment is shown in FIG. 2 to Table 4 will be described.

The pitch p between the control electrodes 42 of the counter electrode 21
Is determined by the size of the matrix and the printing resolution. Each of the electrode width d, the electrode pitch p, the gap t between the counter electrode 21 and the paper 5 and the gap g between the counter electrode 21 and the control electrode 51 of the grid electrode 23 are closely related to crosstalk between adjacent electrodes. It is necessary to define the range within which the influence of the crosstalk is suppressed.

In FIG. 5A, the counter electrode 21 has a structure in which the surface adjacent to each control electrode 42 and the surface on the grid electrode 23 side are covered with an insulating layer 53. This insulating layer 53
Are provided to prevent dielectric breakdown between the control electrodes 42 in the counter electrode 21 and crosstalk with the grid electrode 23 in practice.

Not really, as shown in the figure,
A recording medium guide unit 55 is provided between the insulating layer 53 and the conveyed sheet 5 so that the sheet 5 does not directly contact the counter electrode 21 and the insulating layer 53.

The results measured under various conditions in FIG. 5A will be described below in a table.

<Measurement Example 1> The preconditions for the measurement were as follows: a gap g of 0.5 mm, a gap t of 0.05 mm, a pitch p between the electrodes of 1.0 mm, and a control electrode 4 of the counter electrode 21.
+0.6 kV (toner flying voltage), −
0.3 kV (toner flying suppression voltage), grid electrode 23
Are set to +0.2 kV (toner flying voltage) and -0.2 kV (toner flying suppressing voltage)
Table 2 shows the measurement results of printing when the electrode width d was varied between 0.4 and 0.8 mm.

[0046]

[Table 2]

According to Table 2, if the electrode width d is at least half of the electrode pitch p (d ≧ p / 2), the effect of crosstalk between adjacent electrodes is suppressed, and good printing is possible. More preferably, it is preferable to make the pitch as close as possible to the inter-electrode pitch p within a range in which insulation breakdown between adjacent electrodes does not occur, so that the selection range of other setting conditions such as the applied voltage of the opposing control electrode 42 or the grid control electrode 51 is wider. In addition, the occurrence of crosstalk is reduced.

<Measurement Example 2> The preconditions for the measurement were as follows: the electrode pitch p was 1.0 mm, the electrode width d was 0.8 mm, the gap t was 0.05 mm, and the grid electrode 23 was applied to the control electrode 51. The voltage is +0.2 kV (toner flying voltage),
−0.2 kV (toner flight suppression voltage) and the gap g
Is varied between 0.5 and 1.5 mm, and the printing measurement results when an appropriate voltage is applied to the control electrode 42 of the counter electrode 21 in the gap g are shown in Table 3.

[0049]

[Table 3]

According to Table 3, the gap g between the counter electrode 21 and the control electrode 51 of the grid electrode 23 is equal to the pitch p between the electrodes.
Below (g ≦ p), it is possible to suppress the influence of the crosstalk between the adjacent electrodes and perform good printing. On the other hand, when the pitch between the electrodes is larger than p (g> p), when the toner flying suppression voltage of the control electrode 51 of the counter electrode 21 is low as in Measurement No. 2-3, leakage occurs when the flying is suppressed. Further, when the toner flying suppression voltage of the control electrode 51 of the counter electrode 21 is increased as in Measurement No. 2-4, the print density is low and high density printing cannot be performed. For this reason, the gap g is 0.5 to 1.0 in consideration of the blurring of printing due to the contact between the control electrode 51 of the grid electrode 23 and the paper 5 and the thickness variation due to the paper type and the reduction of the applied voltage to the counter electrode 21. Preferably, it is 5 mm, and conversely, the pitch p between the electrodes must be set to this value or more. However, the electrode width d of the control electrode 42 of the counter electrode 23 is equal to or more than half the electrode pitch p (d
≧ p / 2).

<Measurement Example 3> The preconditions for the measurement were as follows: the electrode pitch p was 1.0 mm, the electrode width d was 0.8 mm, the gap g was 0.8 mm, and the application of the counter electrode 21 to the control electrode 42 was performed. The voltage is +0.6 kV (toner flying voltage), -0.
3 kV (toner flying suppression voltage), the voltage applied to the control electrode 51 of the grid electrode 23 is +0.2 kV (toner flying voltage), -0.2 kV (toner flying suppression voltage), and the gap t is 0.05 to 0. Table 4 shows the printing results when the distance was changed between 30 mm.

[0052]

[Table 4]

As shown in Table 4, the control electrode 4 of the counter electrode 21
Considering the influence of crosstalk between adjacent electrodes, the gap t between the sheet 2 and the sheet 5 has a significant effect on the print quality unless it is 200 μm or less (t ≦ 200 μm). Counter electrode 21
5 is preferably in contact with the gap t between the control electrode 42 and the sheet 5, but in practice, the insulating film 53 is provided as shown in FIG. The thickness of the insulating film 53 is 20 to 200 μm, depending on the voltage applied to the control electrode 42 of the counter electrode 21.
Need to be suppressed. Further, in consideration of the air gap between the control electrode 42 of the counter electrode 21 due to the waving of the paper 5 and the paper 5, the thickness of the insulating film 53 is desirably 100 μm or less. However, the electrode width d of the control electrode 42 of the counter electrode 23 is at least half the inter-electrode pitch p (d ≧ p / 2).
Is a condition.

Therefore, the recording medium guide means can stably convey the paper 5 while keeping the gap t between the control electrode 42 of the counter electrode 21 and the paper 5 at 200 μm or less (t ≦ 200 μm).

From the above three measurement results, the thickness of the insulating layer was suppressed to 200 μm or less (preferably 100 μm or less), and the control electrode 42 of the counter electrode 21 sealed to the insulating layer was
Is equal to or more than half of the electrode pitch p (d ≧ p /
With 2), it is possible to suppress the influence of crosstalk between the adjacent electrodes of the opposing electrode 21 and stably maintain good print quality. Further, by setting the gap g between the counter electrode 21 and the control electrode 51 of the grid electrode 23 to be equal to or less than the electrode pitch p (g ≦ p), the influence of crosstalk can be further suppressed and good printing can be performed.

The measurement examples 1 to 3 are shown in FIG.
The measurement was performed with the configuration of FIG. 5A, but as shown in FIG.
Similar results were obtained when measurement was performed with a configuration in which the control electrode 42 in the counter electrode 21 was entirely covered with the insulating layer 53. In any case, it is necessary to provide the recording medium guide means 55 so that a certain gap is formed between the insulating layer 53 and the paper 5.

As described above, the electric field applied between the toner carrier 19 and the counter electrode 21 changes according to the potential supplied to the counter electrode 21 and the grid electrode 23, and the electric field applied from the toner carrier 19 to the counter electrode 21 changes. Is controlled.

In the above description, a round hole is used as the shape of the gate, but it may be a polygon or a slit. In the case of the slit shape, the intermediate electrode can be simplified and downsized, but it is necessary to consider the influence on adjacent dots.

In the above description, the counter control electrode 42
Although the configuration described above is a line electrode, a number of needle-shaped electrodes corresponding to the gate 26 may be provided, and the needle-shaped electrodes may be wired so as to be time-divisionally controlled. In this case, the influence of the adjacent back electrode can be reduced, and the print dot diameter can be reduced. However, since the electric field intensity formed by the opposing control electrode 42 is stronger as the area of the corresponding opposing control electrode 42 is larger, the control electric field at the needle electrode is less controllable than the line electrode. However, this is within a range in which there is no problem in practical use.

In the above description, the control electrode 42 of the counter electrode 21 is a line electrode that is long in the direction perpendicular to the direction in which the recording medium 5 is conveyed, but may be long in the conveyance direction. In this case, the number of control electrodes 51 of the grid electrode 23 decreases, but the number of control electrodes 42 of the counter electrode 21 increases. Generally, compared to the voltage applied to the grid electrode 23,
Since the voltage applied to the counter electrode 21 is a high voltage, the load on the drive circuit increases and the electrode width and pitch of the control electrode 42 of the counter electrode 21 are controlled by the control electrode 5 of the grid electrode 23.
Must be wider than one.

In the above description, the configuration using the negatively charged toner has been described. However, when the positively charged toner is used, the polarity of each applied voltage may be set as appropriate.

From the above, it is possible to obtain a good print with little influence of the cross talk of the adjacent electrode on the counter electrode, thereby realizing high quality image formation.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG.

FIG. 6 is a diagram showing the configuration between the control electrodes of the opposing electrodes. Here, only the differences from the first embodiment will be described.

When the control electrode 42 having the counter electrode 21, for example, the control electrode Y _i is turned on, the adjacent electrodes Y _{i + 1} , Y _i
i-1 is turned off, and the crosstalk of the adjacent electrode affects. However, at both ends of the opposing electrode 21, only one of them is affected, and an unbalanced state is likely to occur in the flight control at both ends and the center part. Required. Therefore, dummy electrodes 43 are provided on both outer sides of the opposing control electrode 42 as shown in FIG.

The dummy electrode 43 is connected to the counter control electrode 42
And the same width as the electrode width of the opposed control electrode 42. Therefore, during printing, by applying a voltage equivalent to the voltage of the opposing control electrode 42 when the opposing control electrode 42 is turned off, regardless of which control electrode of the opposing control electrode 42 is turned on, the adjacent electrodes on both sides are always turned off. The difference at the center can be eliminated.

Here, the shape, dimensions, and applied voltage of the dummy electrode 43 are set equal to those of the counter control electrode 42 for the sake of simplicity of the device and the control circuit. The shape, size, and applied voltage are not particular.

From the above, it is possible to obtain a good print with little influence of the crosstalk between the adjacent electrodes at the counter electrode, thereby realizing high quality image formation.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG.

FIGS. 7A and 7B are configuration diagrams of the control grid. In this case, the first and the second
Only the description of the parts different from those of the embodiment is described.

The grid electrode (control grid) 23 may be configured such that a common electrode 52 as a second electrode layer is provided on the side parallel to the control electrode 51 of the first electrode layer and close to the toner carrier with the insulator 54 interposed therebetween. Good. In this case, not only the flying amount of the toner 17 is suppressed, but also the change in the charge amount of the toner 17 on the toner carrier 19 using the second electrode layer as a reference potential, or the distance between the toner carrier 19 and the control grid 23. Control electrode 51 and opposing control electrode 4 due to fluctuation of
2 can reduce the influence on the electric field formed. Thereby, stable control can be realized, and a strong electric field strength can be formed with a low applied voltage.

Further, even if the charged toner 17 adheres to the common electrode, the charge is immediately removed, so that the influence of the attached charged toner on the flight control can be eliminated. If the voltage applied to the common electrode 52 is set to 0 V, the driving circuit can be reduced, but a potential other than 0 V may be applied.

Further, as described in the first embodiment, when the potential difference in the toner flying direction of the control grid 23 at the time of flying toner is increased, the amount of toner collected by the control grid 23 increases, and There is a possibility that clogging may occur due to the toner 17 attached to the toner 23. For this reason, it is desirable that the potential is at least lower than the absolute value of the potential of the opposing control electrode 42 when the toner flies. More preferably, if the electric field strength in the toner flying direction formed by the grid control electrode 51 is equal to or less than the electric field strength in the toner flying direction formed by the opposing control electrode 42, the toner 17 can be efficiently discharged in the paper direction. .

In the control of the grid control electrode 51, if an electric field for suppressing the flying of toner is formed in all the grid control electrodes 51 for an arbitrary time before the potential of the opposing control electrode 42 is switched, the control grid 23 passes through the control grid 23. As a result, the potential of the opposing control electrode 42 is switched before adhering to the sheet 5, and it is possible to prevent the toner from adhering to the surface of the control grid 23 opposing the sheet recording surface, thereby preventing contamination due to contact with the sheet.

From the above, it is possible to obtain good printing with little influence of crosstalk between adjacent electrodes on both the grid electrode and the counter electrode, thereby realizing high quality image formation.

(Application Example) A case in which the image forming apparatus according to the present invention is applied to a digital copying machine will be described with reference to FIGS.

As shown in FIG. 8, the digital copying machine according to this application example includes an image forming unit 1 having a toner supplying unit 2 and a printing unit 3. This image forming means 1
This is to visualize an image corresponding to an image signal on a sheet as a recording medium using toner as visualized particles.

On the paper supply side A of the paper 5 to the image forming means 1, a paper cassette 4 containing the paper 5 as a recording medium, a paper feed roller 6 for feeding the paper 5 from the paper cassette 4, a supplied paper The sheet detecting member 7 that is driven by the sheet detecting member 5 moves, the sheet feed sensor 8 that detects that the sheet 5 is supplied by the movement of the sheet detecting member 7, and the sheet 5 supplied from the sheet cassette 4 is imaged at a predetermined timing. A registration roller 9 to be supplied to the forming unit 1 is provided.
On the other hand, a fixing unit for fixing the toner image formed on the sheet 5 by the image forming unit 1 to the sheet 5 by heating or pressing, or both, on the discharge side B of the sheet 5 from the image forming unit 1 10, a paper discharge roller 11 for discharging the paper 5 processed by the fixing unit 10 onto a paper discharge tray 14, a paper detection member 12 driven and moved by the paper 5 to be discharged,
A paper discharge sensor 13 that detects that the paper 5 has been discharged by the movement of the paper detection member 12 and a paper discharge tray 14 that receives the discharged paper 5 are provided. The configuration of the image forming unit 1 is the same as the configuration of FIG. 1 described above.

The system configuration of the entire digital copying machine in this application example will be described with reference to FIG.

As shown in FIG. 9, the system configuration block includes a main control unit 31 for controlling the entire digital copying machine,
An image processing unit 32 that converts image data obtained from the image reading unit 24 into a format of image data to be printed; an image forming control unit 33; and electrode units of the image forming unit 1 (toner carrier 19, A power supply unit (power supply unit) 29 for applying a potential to the control electrode of the electrode 21 and each control electrode of the grid electrode 23) is provided.

The image reading section 24 scans, for example, a document placed on a transparent document placing table (not shown) by an optical scanning means, and reflects the reflected light on a CCD (Char).
The image data is converted into an image signal by a Ge Coupled Device to obtain image data. Image processing unit 3
2 is provided with, for example, an image memory formed of a magnetic recording medium such as a semiconductor memory or a hard disk, and converts the image data obtained from the image reading unit 24 into a format of image data to be printed. Then, the processed image data is stored in an image memory (not shown).

The image formation control unit 33 constitutes an image formation control section 34, a data processing section 35, and an electrode potential control means for the grid electrode potential and the counter electrode potential together with the image formation control section 34 and the data processing section 35. A print control unit (print control unit) 36 and a process control unit 37 are provided. The image forming control unit 34 includes the image processing unit 3
2 is converted into image data to be given to the print control unit 36. Specifically, for example, a character code indicated by the image data is converted into a dot sequence. Further, the image forming control section 34 outputs the voltage output from the power supply section (power supply section) 29 to the image forming section 1.
(The toner carrier 19, the control electrode of the counter electrode 21, the control electrode of the grid electrode 23, etc.). The data processing unit 35 decomposes the image data processed by the image formation control unit 34 according to the number of electrode rows of the grid electrode 23. The print control unit (print control unit) 36 generates a grid voltage control signal and a counter voltage control signal for controlling the potentials of the grid electrode 23 and the counter electrode 21 based on the image data input from the data processing unit 35. And a print head 22 and a counter electrode control unit (counter electrode control means) 1
Give 5 The process control unit 37 includes the image forming control unit 3
In accordance with the command given from step 4, a control signal corresponding to each process is given to each section.

Next, the image forming operation will be described.

1) When a document to be copied is placed on the image reading section 24 and the copy start button is operated, the main control section 31 receiving this input starts the image forming operation.
That is, a document image is read by the image reading unit 24.

2) The image data read by the image reading unit 24 is processed by the image processing unit 32, and the image is temporarily stored in an image memory (not shown).

3) The main motor (not shown) operates. The paper 5 in the paper cassette 4 is sent out toward the image forming unit 1 by the paper feed roller 6 driven by the main motor. When the sheet detecting member 7 is pushed up by the sheet 5, the sheet feeding sensor 8 detects that the sheet is in a normal sheet feeding state by this operation. Thereafter, the leading end of the sheet comes into contact with the registration roller 9 which is stationary, and stops at once.

4) When the normal paper feed is detected by the feed sensor 8, the image data stored in the image memory is transferred to the image forming control unit 33.

5) The image forming control unit 33 converts the input image data into the print head 22 and the counter electrode control unit 1.
5 begins to be converted to a control signal. When a predetermined amount of the control signal is obtained, the image forming control unit 33 activates the registration roller 9 to cause the sheet 5 to move the opposing electrode 21 of the printing unit 3 of the image forming unit 1 on the surface facing the toner carrier 19. To the side. The transported paper 5 is guided and transported by a recording medium guide unit (not shown). The predetermined amount of the control signal differs depending on the configuration of the digital copying machine.

6) Thereafter, the image forming control unit 33 sends the control signal to the print head 22 and the counter electrode control unit 15. The control signal is supplied at a timing synchronized with the supply of the paper 5 to the printing unit 3 by the registration roller 9.

7) Print Head 22 and Counter Electrode Controller 15
Then, the grid electrode control unit 40 and the counter electrode control unit 41 shown in FIG.
8 is controlled. As a result, a voltage is appropriately applied from the driver 39 to a predetermined control electrode, and the electric field in the vicinity of the print head 22 and the counter electrode control unit 15 is controlled. That is, at the gate 26 of the grid electrode 23, the prevention of the toner from flying from the toner carrier 19 to the counter electrode 21 and the release thereof are appropriately performed according to the image data. As a result, a toner image corresponding to the image signal is formed on the paper 5.

8) The paper 5 on which the toner image has been formed is conveyed to the fixing means 10, where the toner image is fixed on the paper.

9) The sheet 5 on which the toner image has been fixed is discharged onto a discharge tray 14 by a discharge roller 11. At this time, the sheet detection member 12 is pushed up by the sheet 5, and the sheet ejection sensor 13 detects that the sheet 5 is normally ejected by this operation. By this detection, the main control section 31 determines that the printing operation on the paper 5 has been completed normally.

As described above, the digital copying machine in this application example is
By using the image forming apparatus of the present invention, stable print quality can be obtained, and a high-quality image can be realized.

The embodiments and application examples described above are not limited to the above description unless the gist of the present invention is changed.

[0095]

According to the image forming apparatus of the present invention, the following effects can be obtained in each claim.

According to the first and second aspects of the present invention, it is possible to obtain good printing with little influence of crosstalk between adjacent electrodes at the counter electrode, thereby achieving high quality image formation. doing.

According to the third aspect of the present invention, high-density printing can be performed even when the voltage applied to the counter electrode is reduced, and furthermore, the printing is blurred due to the contact between the grid electrode and the recording medium and the thickness variation due to the type of paper. Has the effect of being able to respond favorably.

Take into account

[Brief description of the drawings]

FIG. 1 is a structural diagram for explaining a main part of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view showing a configuration of a counter electrode and a grid electrode of an image forming unit in the first embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a diagram schematically illustrating an image forming operation in an image forming unit of the present invention and a conventional image forming apparatus.

FIG. 4 is an explanatory diagram showing a configuration for applying a potential to a counter electrode and a grid electrode of an image forming unit in the first embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a configuration diagram illustrating a shape position of a counter electrode and a grid electrode of an image forming unit in the first embodiment of the image forming apparatus according to the present invention.

FIG. 6 is a perspective view illustrating a configuration of a counter electrode and a grid electrode of an image forming unit in a second embodiment of the image forming apparatus according to the present invention.

FIG. 7 is a configuration diagram showing a shape position of a counter electrode and a grid electrode of an image forming unit in a third embodiment of the image forming apparatus according to the present invention.

FIG. 8 is a schematic diagram for explaining an overall configuration of an application example to which the image forming apparatus according to the present invention is applied.

FIG. 9 is a block diagram for explaining system control of an application example to which the image forming apparatus according to the present invention is applied.

FIG. 10 is a configuration diagram of a conventional image recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming means 2 Toner supply means 3 Printing means 15 Counter electrode control part (means) 19 Toner carrier 21 Counter electrode 22 Print head 23 Control grid 26 Gate

Claims (2)

[Claims] 1. A developing particle carrier, a counter electrode disposed to face the developing particle carrier, and a plurality of control electrodes arranged in one direction, and the developing particle carrier. A plurality of control electrodes are arranged between the counter electrodes, and a plurality of control electrodes are juxtaposed in a direction different from the arrangement of the control electrodes of the counter electrode, and a gate is formed at a position overlapping each control electrode of the counter electrode in the counter direction. A control grid, and an electrode potential control means for controlling the flight of the visualized particles from the carrier for visualizing particles to the counter electrode through the gate in accordance with an image forming signal, and attaching the particles to a recording medium to form an image. An image forming apparatus comprising: the counter electrode, wherein at least a surface adjacent to the control electrode and a surface on the control grid side are sealed with an insulating layer. 2. The insulating layer according to claim 1, wherein said insulating layer has a thickness of 200 μm or less, and a control electrode width of a counter electrode sealed in said layer is at least half of a pitch between said control electrodes. 2. The image forming apparatus according to 1.