JP2000263834A - Direct printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct printer which can print a sharp image by eliminating interference of electrodes between adjacent holes. SOLUTION: First control electrodes 68 of holes 56 adjacent in main scanning direction are interconnected and second control electrodes 70 of holes 56 adjacent in sub-scanning direction are also interconnected. The first and second control electrodes 68, 70 of respective holes 56 are arranged such that print particles 38 pass through the hoes 56 when voltages for permitting flight of print particles is applied thereto. Voltages being applied to the first and second control electrodes 68, 70 are differentiated from each other. Alternatively, print timing of each dot is provided with a time band for prohibiting simultaneous flight of print particles to all electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct printing apparatus used for a copying machine, a printer and the like.

[0002]

2. Description of the Related Art U.S. Pat.
No. 7250 discloses a direct printing apparatus. In this direct printing apparatus, a toner carrier for holding a toner, a back electrode facing the toner carrier, and a plurality of holes arranged between the back electrode and the toner carrier and surrounding these holes are provided. And a print station comprising a print head having electrodes. The back electrode of this printing station is connected to a power supply, which creates an electric field between the toner carrier and the back electrode that sucks the toner on the toner carrier and flies through the holes in the print head to the back electrode side. ing. A sheet passage is formed between the print head and the back electrode.

In the above-described direct printing apparatus, when an ON voltage is applied to the electrodes of the print head, the toner on the toner carrier flies due to the toner attraction by the electric field between the toner carrier and the back electrode, and passes through the holes to form a sheet. Stick on top. When an off-voltage is applied to the electrodes of the print head,
The toner suction force does not reach the toner on the toner carrier, and the toner does not fly. When the on / off voltage applied to the electrodes of such a print head is controlled based on a desired image signal, an image composed of a large number of pixels (presence or absence of toner dots) is printed on a sheet. .

[0004]

In such a direct printing apparatus, a large number of drivers I for controlling the electrodes of the print head are used.
C was required, and there were limitations on cost reduction and printing speed. Therefore, in order to reduce the number of driver ICs, two holes are provided in each hole, the first layer is connected in the main scanning direction, and the second layer is connected in the sub-scanning direction. So-called matrix control has been proposed.
In such matrix control, interference between holes may occur due to the influence of electrodes of adjacent holes called crosstalk. That is, when an electrode of a certain hole is on and an electrode of an adjacent hole is off, toner is caused to fly even in a hole having an off electrode due to an on electrode, or conversely, is affected by an off electrode. In some cases, the toner may be hindered by the holes having the electrodes. It is difficult to completely avoid such crosstalk due to practical limitations such as the ability of the driver IC to control the electrodes.

The present invention has been made in view of the above problems, and has as its object to provide a direct printing apparatus capable of printing sharp images without interference of electrodes between adjacent holes. is there.

[0006]

Means for Solving the Problems As a means for solving the above-mentioned problems, a first invention is to directly attach print particles to a printing medium and print an image consisting of dots of the print particles. In a printing apparatus, a holding member that holds printing particles charged to a predetermined polarity and an electric field that is disposed to face the holding member and electrically attracts and flies the printing particles held by the holding member are formed. A back electrode that is disposed between the holding member and the back electrode, a plurality of holes through which the print particles can pass, and a control electrode that is disposed around the holes, and a print head including: The control electrode includes a driver that applies a voltage that allows the print particles to fly based on an image signal and a voltage that does not allow the print particles to fly. Two control electrodes are provided for each hole, and the control electrodes are adjacent in the main scanning direction. The first of each hole By connecting the control electrodes to each other and connecting the second control electrodes of the adjacent holes in the sub-scanning direction to each other, the first control electrode and the second control electrode of each hole allow the print particles to fly. When the applied voltage is applied, the printing particles pass through the holes, and the voltages applied to the first and second control electrodes are different from each other.

[0007] In the direct printing apparatus of the present invention having the above-described configuration, the first control electrode has a function of peeling the printing particles on the holding member, and the second electrode moves the printing particles in the hole. Has functions. The function of the first control electrode must be strong during printing, and the function of the second control electrode must be strong during non-printing. For this reason, the first control electrode is set to a potential that emphasizes ON, and the second control electrode is set to a potential that emphasizes OFF. Thereby, the functions of the first and second control electrodes can be sufficiently exhibited, and as a result, a sharp image without crosstalk can be printed.

According to a second aspect of the present invention, there is provided a direct printing apparatus for printing an image composed of dots of print particles by directly attaching print particles to a medium to be printed. A holding member that holds the printing particles charged to a polarity, a back electrode that is arranged to face the holding member, and forms an electric field that electrically attracts and flies the printing particles held by the holding member to fly; A print head provided between a holding member and the back electrode, the print head including a plurality of holes through which the print particles can pass, and a control electrode disposed around the hole; and an image signal applied to the control electrode of the print head. And a driver for applying a voltage that allows the print particles to fly and a voltage that does not allow the print particles to fly. Control electrodes By connecting and connecting the second control electrodes of the holes adjacent to each other in the sub-scanning direction, a voltage allowing the print particles to fly is applied to the first control electrode and the second control electrode of each hole. The printing particles pass through the holes when the printing is performed, and a time zone is provided in which a voltage that does not allow the printing particles to fly is simultaneously applied to all the electrodes at the printing timing of each dot.

In the direct printing apparatus according to the present invention having the above-described configuration, when the first control electrode is on and the second control electrode is off, the printing on the holding member is performed by the first control electrode that is turned on. Some of the particles begin to fly, but are not moved through the holes by the second control electrode. However, if this condition continues, print particles may spill through the holes due to the accumulation of the effect of slight movement. However, in the present invention, at the printing timing of each dot, a time period in which a voltage that does not allow the printing particles to fly is applied to all the electrodes at the same time is provided, and the printing particles that have started moving are returned to the holding member side. In addition, spilling of printing particles is eliminated, and crosstalk is also prevented.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a direct printing apparatus 2 according to a first embodiment of the present invention. The direct printing apparatus 2 has a sheet supply station indicated by reference numeral 4.
The sheet supply station 4 has a cassette 6 in which sheets 8 such as paper as a printing medium are stacked and stored. A sheet supply roller 10 is disposed above the cassette 6 and rotates while contacting the uppermost sheet 8.
The sheet 8 is sent out to the inside of the printing device 2. In the vicinity of the sheet supply roller 10, a pair of timing rollers 12 is provided.
And a printing station (generally indicated by reference numeral 16) for forming an image of a printing material on the sheet 8 fed from the cassette 6 along a sheet path 14 indicated by a dashed line. ). Printing device 2
It also has a fixing station 18 for permanently fixing the image of the printing material to the sheet 8 and a stacking station 20 for receiving the sheet 8 to which the image of the printing material has been fixed.

As shown in FIG.
Has a developing device generally indicated by reference numeral 24 on the sheet passage 14. The developing device 24 has a container 26 in which an opening 28 facing the sheet passage 14 is formed. Inside the container 26 and near the opening 28, a developing roller 30 as a printing material holding member is supported rotatably in the direction of arrow 32. The developing roller 30 is made of a conductive material and is electrically grounded. A blade 36 is arranged on the outer peripheral surface of the developing roller 30 in contact therewith.
6 is preferably made of a plate made of rubber or stainless steel. The container 26 contains the printing material or toner particles 3.
8 are accommodated. In the present embodiment, as the toner particles 38, those that are negatively charged are used.

Below the seat passage 14, the whole is denoted by reference numeral 4.
The electrode mechanism denoted by 0 is the developing roller 30 of the developing device 24
And are arranged to face. This electrode mechanism 40
Has a support 42 made of an insulating material and a back electrode 44 made of a conductive material. The back electrode 44 is connected to a DC power supply 46 that supplies a voltage of a predetermined polarity (positive in this embodiment) to the back electrode 44, and a voltage of, for example, +1200 volts is applied. Thereby, an electric field is formed between the back electrode 44 and the developing roller 30 so that the negatively charged toner particles 38 on the developing roller 30 are electrically attracted to the back electrode 44. Has become.

A print head, generally designated by reference numeral 50, is fixed between the developing device 24 and the electrode mechanism 40 and above the sheet passage 14. The print head 50 is preferably made of a flexible printed circuit board having a thickness of about 100-200 μm. As shown in FIG. 2 and FIG.
The portion of the print head 50 located in the print area 54 facing the back electrode 44 has a plurality of holes 56. Each hole 56 has an average particle size of the toner particles 38 (from about several μm to 10 μm).
Several μm), about 25 to 200 μm
Having a diameter of

As shown in FIG. 3, the hole 56 extends in the main scanning direction 64 in the present embodiment, and
(Hereinafter referred to as the sub-scanning direction.) Three rows are provided along parallel lines 58, 60 and 62 arranged at equal intervals, and the print head has a resolution of 600 dpi. The hole 56 on each line 58, 60 and 62 has a distance D (125μ).
m) and are formed at equal intervals, and the line 58 and the line 62
The upper holes 56 (56a) and 56 (56c) have different distances (D / n) (n is the number of columns and 3 in this embodiment) from the hole 56 (56b) on the center line 60 in different directions. .)
, So that when viewed from the sub-scanning direction 66, the holes 56 appear to be arranged at equal intervals as a whole. The distance D and the number of columns are appropriately set according to the resolution.

As shown in FIG. 4, the flexible printed circuit board 52 also has a first circular electrode 68 and a second circular electrode 70 surrounding each hole 56. The first electrode 68 is arranged on one side facing the developing roller 30, and the second electrode 70 is arranged on the side facing the back electrode 44.

As shown in FIG. 5A, the first electrode 68 has a sub-scanning direction 66 (in this embodiment, the sub-scanning direction 66).
(A slightly inclined direction with respect to the first driver 72) are printed wirings 74a, common to each driver IC of the first driver 72.
74b, 74c,. . . Are electrically connected via On the other hand, of the second electrodes 70, as shown in FIG.
6, printed wiring lines 78a, 78b, 7 common to the driver ICs.
8c. The control signals X1, X2, and X2 are supplied from the driver 72 to the first electrode 68 of each row.
X3,. . . Is transmitted from the driver 76 to the second
Control signals Y1, Y2, and Y3 are transmitted to the electrode 70. Also, the first driver 72 and the second driver 7
6, is electrically connected to a controller 80 that outputs data of an image created by the printing apparatus, as shown in FIG.

More specifically, in the present embodiment, as shown in FIG. 6, for the control electrode X of the first electrode 68, for example, the base voltage V1 (B) of the DC component is about -1.
00 volts, the pulse voltage V1 (P) of the pulse component is approximately +
It is 300 volts. For the control electrode Y of the second electrode 70, for example, the base voltage V2 (B) of the DC component is about -200 volts, and the pulse voltage V2 (P) of the pulse component
Is about +200 volts. Then, the first electrode 68
The pulse voltage is applied to the second electrode 70 and the second electrode 70 so that the toner flies only in the holes that are turned on to print an image.

As shown in FIG. 7, the control signals Y1, Y2, and Y3 transmitted to the second electrode 70 are, as shown in FIG. 7, signals which sequentially change to the ON potential so as not to overlap with each other, with a period P (300 μsec). Is repeated.

On the other hand, the image signals X1, X2, X3,... Transmitted to the first electrode 68 correspond to the second electrodes corresponding to the holes to be printed among the plurality of holes connected to those lines. It is provided so as to be turned on in synchronization when the control signal of 70 is turned on.

Next, the basic operation of the direct printing apparatus 2 having the above configuration will be described.

At the printing station 16, as shown in FIG. 2, the developing roller 30 rotates in the direction indicated by the arrow 32. The toner particles 38 are supplied to the developing roller 30 and conveyed to a contact area between the blade 36 and the developing roller 30, where a negative electrostatic charge is applied to the toner particles 38 by contact with the blade 36. Thus, as shown in FIG. 4, the outer peripheral portion of the developing roller 30 passing through the contact area carries a thin layer of the charged toner particles 38.

In the print head 50, the second electrode 70 is
The control signals Y1, Y2, Y3 of the potential pattern shown in FIG. On the other hand, when the toner particles do not fly, the first electrode 68 has a base voltage V of about -100 volts.
(B) is applied to the first electrode 68. Therefore,
The negatively charged toner particles 38 on the developing roller 30 are electrically repelled from the first electrode 68 and accumulate on the developing roller 30 without flying toward the hole 56.

The controller 80 outputs image data corresponding to the image to be reproduced to the driver 72. In response to this image data, the driver 72 applies a pulse voltage V (P) (about +300 volts) to the first electrode 68 as shown in FIG. For example, in the first printing cycle P1, FIG.
When a dot D1 at a position indicated by hatching is formed, as shown in FIG. 7, X2 is turned on in synchronization with Y1 being turned on. Further, when dots D2 and D3 indicated by hatching in FIG. 5 are formed in the next printing cycle P2, as shown in FIG.
Is turned on, and X1 is turned on in synchronization with Y3 being turned on.

As a result, the toner particles 38 at the portion of the developing roller 30 facing the electrode to which the pulse voltage is applied
Is electrically attracted to the control electrode 62. As a result, a large number of toner particles 38 are activated and fly toward the opposing hole 56 by the suction force of the back electrode 44, and a lump of the toner particles 38 is transferred from the sheet supply station 4 to the printing area 5.
An image is formed on the sheet 8 by adhering to the sheet 8 supplied to the sheet 4.

The sheet 8 on which the image is formed as described above is
The toner particles are conveyed to the fixing station 18 where they are heated and permanently fixed on the sheet 8 and finally discharged onto the stacking station 20 or the catch tray.

It should be noted here that the potentials of the first electrode 68 and the second electrode 70 are set differently in consideration of the functions of the first electrode 68 and the second electrode 70.

The function of the first electrode 68 is to peel off the toner particles 38 from the developing roller 30 when the first electrode 68 is on. Therefore, by increasing the on-potential of the first electrode 68 as much as possible to attract the toner particles 38, the function can be exerted more strongly. Further, the off-potential need not be lowered so much as it only needs to realize a negative function of preventing the toner particles 38 from falling into the holes 56.

On the other hand, the function of the second electrode 70 is to prevent the toner particles 38 from being drawn into the hole 56 when the second electrode 70 is off, and to reliably stop the toner particles 38 from entering the hole 56. Therefore, by making the off-potential of the second electrode 70 as low as possible (in the direction of the same polarity as that of the toner particles 38) and repelling the toner particles 38, the function can be exerted more strongly. In addition, the ON potential is only required to have a weak effect of allowing the toner particles 38 entering the holes 56 to pass through, so that a very high potential is not required. The lower the on-potential, the better the convergence, and there is also an advantage that a sharp image can be obtained.

Therefore, as shown in FIG.
Is +300 volts, which is set higher than the on potential +200 of the second electrode 70 in the direction in which the toner particles 38 are attracted. The off-potential of the second electrode 70 is
At -200 volts, the off-potential of the first electrode 68 is set lower than -100 volts in a direction in which the toner particles 38 are repelled. By setting the potentials of the first electrode 68 and the second electrode 70 as described above, sharp toner control can be performed, and interference of the electrodes in the adjacent holes 56 can be prevented, so that crosstalk can be avoided.

(Second Embodiment) A direct printing apparatus according to a second embodiment of the present invention is different from the first embodiment only in the potential pattern to the first electrode 68 and the second electrode 70. Since it is the same as the direct printing device 2 described above, the description is omitted.

FIG. 8 shows a potential pattern of the first electrode 68 and the second electrode 70 of the direct printing apparatus according to the second embodiment. Second
Control signals Y1, Y2, Y transmitted to the electrodes 70, respectively.
In No. 3, a signal that sequentially changes to an on-potential so as not to overlap each other and with a time t during which all the electrodes are turned off is periodically repeated at a period P (330 μsec).

On the other hand, the image signals X1, X2, X3,... Transmitted to the first electrode 68 correspond to the holes 56 for printing among the plurality of holes 56 connected to those lines.
The control signal is provided so as to be turned on in synchronization with the control signal of the corresponding second electrode 70 being turned on. And Pd
In the case of discontinuous dot forming pulses such as 1, Pd2, and Pd3, when they are turned off, a time t (10 μsec in this embodiment) when all the electrodes are turned off is given. In the case of continuous dot forming pulses such as Pd4, Pd5, and Pd6, a time t during which all the electrodes are turned off is given between them.

As described above, the first electrode 68 and the second electrode 70
The reason why the time t at which all the electrodes are turned off is given to the potential pattern is as follows.

That is, the matrix control utilizes the characteristic that if one of the X line and the Y line is off, the toner does not fly and the image is not printed even if the other is on. However, particularly when the first electrode 68 of the X line is turned on, even if the second electrode 70 of the Y line is turned off, the toner particles 38 slightly separate from the developing roller 30 and move toward the print head 50 even though the second electrode 70 of the Y line is off. I do. If this “X-ON, Y-OFF” state ends with one dot forming pulse, the toner particles 38 are immediately transferred to the developing roller 30.
There is no problem as we return to the side. However, "X-ON, Y
The state of "-off" may be continued for several dots. For example, as shown in FIG. 9, “X2, Y1”, “X2, Y
In the case where dots are continuously formed at “X2, Y3”, after the dots are formed at “X2, Y1”, the time zone of t _OFF is “X2, Y2” and “X2, Y3”. While the two dots are formed, the state is "X-ON, Y-OFF", and the toner particles 38 move little by little, and the holes 56 may be clogged with the toner particles 38 or may be partially spilled.

Therefore, in the second embodiment, as shown in FIG. 8, by providing a time zone t during which all the electrodes are turned off, the toner particles 38 are returned to the developing roller 30 to prevent clogging and spillage. Thereby, crosstalk can be avoided without interference of the electrodes of the adjacent holes 56.

The developing device 24 shown in FIG. 2 used in the direct printing device 2 of the above embodiment is not limited to the above-described developing device. For example, any type of developing device used in an electrophotographic image forming apparatus can be used. It can be used instead of the developing device 24.

As described above, the present invention has been described with reference to the specific embodiments. However, it is obvious that modifications and variations may be made without departing from the scope of the invention described in the claims. .

[0039]

As is apparent from the above description, according to the first aspect, the voltages applied to the first and second control electrodes are different from each other. 2
The function of the control electrode can be sufficiently exhibited, and a sharp image without crosstalk can be printed.

According to the second aspect of the present invention, at the time of printing dots, a time period is provided for simultaneously applying a voltage that does not allow the printing particles to fly to all the electrodes. Return the particles to the holding member side,
The spill of the printing particles is eliminated, and the crosstalk is also prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a direct printing apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a printing station.

FIG. 3 is an enlarged plan view of a print head.

FIG. 4 is an enlarged cross-sectional view taken along the line IV-IV of FIG. 3, showing a print head, a developing roller, and a back electrode.

FIG. 5A is a plan view showing a wiring of a first control electrode,
(B) is a plan view showing the wiring of the second control electrode.

FIG. 6 is a diagram showing potentials of signals to a first control electrode and a second control electrode.

FIG. 7 is a diagram showing signals to a first control electrode and a second control electrode.

FIG. 8 is a diagram showing signals to a first control electrode and a second control electrode of the direct printing apparatus according to the second embodiment of the present invention.

FIG. 9 is a diagram showing signals to a first control electrode and a second control electrode when there is no time for turning off all the electrodes.

[Explanation of symbols]

 2 Direct printing apparatus 8 Sheet (medium to be printed) 30 Developing roller (holding member) 38 Toner particles (printing particles) 44 Back electrode 46 Power supply 50 Print head 56 Hole 68 First control electrode 70 ... Second control electrode 64 ... Driver

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Satoshi Shibata F-term (reference) 2C162 AE25 AE31 AE47 AF07 AF13 AF52 AF70 AH06 AH15 in 2-3-1, Azuchicho, Chuo-ku, Osaka-shi, Osaka CA02 CA12 CA24 2H029 AB07 AB16 AC02 AD01

Claims (2)

[Claims] 1. A direct printing apparatus for printing an image composed of dots of print particles by directly attaching print particles to a printing medium, comprising: a holding member for holding print particles charged to a predetermined polarity; A back electrode that is arranged to face the holding member and forms an electric field for electrically attracting and flying the print particles held by the holding member, and a back electrode that is arranged between the holding member and the back electrode; A print head comprising a plurality of holes through which the particles can pass and a control electrode disposed around the holes; and a voltage and an allowance which allow the control electrodes of the print head to fly the print particles based on an image signal. And a driver for applying a voltage that does not apply. The control electrode is provided two for each hole, the first control electrodes of the holes adjacent in the main scanning direction are connected to each other, and the control electrodes Second control of holes Connecting the poles to each other so that the print particles pass through the holes when a voltage allowing the print particles to fly is applied to the first control electrode and the second control electrode of each hole, A direct printing apparatus, wherein voltages applied to the first and second control electrodes are different from each other. 2. A direct printing apparatus for printing an image consisting of dots of printing particles by directly attaching the printing particles to a printing medium, comprising: a holding member for holding printing particles charged to a predetermined polarity; A back electrode that is arranged to face the holding member and forms an electric field for electrically attracting and flying the print particles held by the holding member, and a back electrode that is arranged between the holding member and the back electrode; A print head comprising a plurality of holes through which the particles can pass and a control electrode disposed around the holes; and a voltage and an allowance which allow the control electrodes of the print head to fly the print particles based on an image signal. And a driver for applying a voltage that does not apply. The control electrode is provided two for each hole, the first control electrodes of the holes adjacent in the main scanning direction are connected to each other, and the control electrodes Second control of holes Connecting the poles to each other such that the print particles pass through the holes when a voltage allowing the print particles to fly is applied to the first control electrode and the second control electrode of each hole, A direct printing apparatus, characterized in that a time zone in which a voltage that does not allow the printing particles to fly is applied to all the electrodes simultaneously at the dot printing timing is provided.