JPH10193703A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a high quality print while holding a print medium surely and stably on a rotary member. SOLUTION: A print medium M is attracted electrostatically to the outer circumferential surface 11, 12 of a rotary member 10 rotatable at a constant circumferential speed and ink is jetted from an ink jet nozzle to the turning print medium M along with the rotary member 10. The rotary member 10 is brought into contact with the outer circumferential surface 11, 12 and neutralized before attraction to the print medium M and/or after printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating member rotatable at a constant peripheral speed, which uses a charge attracting force to suck and hold a printing medium, and prints a rotating printing medium together with the rotating member from an ink jet nozzle. The present invention relates to an ink jet printer formed so as to be able to print while spraying ink.

[0002]

2. Description of the Related Art A nozzle head for each color is reciprocated over the entire length in a row direction, and printing is performed during each forward movement to print one line, and after one line printing, a printing medium (plain paper, OHP paper, etc.).
Compared to a so-called serial type ink-jet printer which feeds M by one line in the column direction and repeats them, printing speed can be drastically increased and continuous printing operation can be performed over a large number of sheets. The present applicant has proposed an ink-jet printer capable of achieving a great reduction in size (for example, Japanese Patent Application No. 8-296959).

In FIG. 4, a drum (rotating member) 10 is rotatable at a constant peripheral speed and can hold a print medium M on an outer peripheral surface 11 thereof. That is, the print medium M is held on the outer peripheral surface 11 of the drum 10 by using the holding force of the medium holding means, and is rotationally transferred by using the rotation of the drum 10.

A nozzle head (print head) 200 for each color is arranged in the rotation (Y) direction of the drum 10. Therefore, an integrated nozzle head 200 for each color or an integrated nozzle head 200 for each color in which a plurality of nozzle head elements are arranged in the row direction over the entire length in the row direction (perpendicular to the paper surface), for example, by the pitch between inkjet nozzles. Ink is sprayed from the inkjet nozzles 207 for each color onto the rotating print medium M while being reciprocated, thereby printing in the row direction, and printing in the column direction using the rotation of the drum 10 during the forward movement of the pitch between the inkjet nozzles. Can be. That is, since the line-direction printing and the column-direction printing can proceed simultaneously, the printing speed can be greatly increased.

Further, since the nozzle heads 200 for each color and the ink tanks (ink cassettes) 213 for the respective colors are arranged at separate positions, the nozzle heads 200 for the respective colors are provided.
In addition to the fact that the printing speed can be reduced and the reciprocating speed in the row direction can be greatly increased, the printing speed can be further increased, and the capacity of the ink tank (ink cassette) 213 for each color can be greatly increased. This allows continuous printing operation.

In order to realize these, one side (right side in FIG. 4) of the drum 10 is provided with a feeding means 60 and a medium feeding means 9.
0, and on the other side (left side in FIG. 4), the medium peeling means 140, the medium discharge / conveyance means 160, and the direction switching means 190
Are provided.

The feeding means 60 can selectively feed the printing medium M one by one from one of the cassette feeding means 71 and the manual feeding means 61. The medium supply means 90 feeds the fed print medium M to the drum 1 at a predetermined timing.
Feed to the 0 side. The medium peeling means 140 peels the print medium M from the drum 10 after printing, and
0 discharges and conveys the peeled print medium M to the left in FIG. The direction switching unit 190 selectively switches between the discharge tray 192 and the upper discharge tray 193.

Thus, the feeding, supply, holding, rotational transfer, printing, peeling, and discharging and conveying of the printing medium M can be continuously performed, so that multicolor printing of, for example, 20 sheets or more of A4 size in one minute can be performed. it can.

Here, in order to obtain the holding force of the printing medium M, it is conceivable to construct the printing medium M by using any one or an arbitrary combination of a charge attracting force, a negative pressure attracting force, and a mechanical clamping force. In particular, for miniaturization, adoption of a charging means utilizing a charge attracting force is effective.

[0010]

Therefore, charging means is
The printing medium M supplied to the outer peripheral surface 11 of the rotating rotating member (10) was charged while the charging roller was in contact with the printing medium M. The printing medium M was extremely small and could be held in close contact with the outer peripheral surface 11.

However, when a continuous printing operation is performed for a large number of sheets, for example, more than 200 sheets, the trailing edge of the printing medium M is particularly likely to be lifted. Such a situation often occurs when an electric insulating layer having a high electric resistance value (volume resistivity), for example, a mylar sheet is formed on the outer peripheral surface 11 in order to improve the charging efficiency or maintain the charge attracting force. This hinders stable high-quality printing.

An object of the present invention is to provide an ink jet printer capable of stably performing high quality printing while reliably and stably holding a printing medium on a rotating member.

[0013]

Means for Solving the Problems When the specifications were measured for each continuous printing operation time, a charging phenomenon occurred on the outer peripheral surface of the rotating member (especially when an electric insulating layer was formed) and the operation time was prolonged. Tend to increase the electric charge. Moreover,
A decrease in the charge adsorbing power of the print medium is observed with the increase in the charge amount.

Thus, the present invention achieves the above object by forming, for example, a charge remaining on the rotating member after the previous printing medium is peeled off from the rotating member.

That is, according to the first aspect of the present invention, a print medium is sucked and held on the outer peripheral surface of a rotatable member rotatable at a constant peripheral speed by using a charge attraction force, and an ink jet nozzle is attached to the print medium rotating with the rotatable member. The printing apparatus is characterized in that it is formed so as to be printable while spraying ink from above, and that the rotating member is formed so as to be in contact with the outer peripheral surface before suction holding of the print medium and / or after printing so that the rotating member can be neutralized.

In this invention, for example, after the previous printing medium is printed, or after the subsequent printing medium is peeled off, or before the next printing medium is attracted and held, for example, a discharging brush is brought into contact with the outer peripheral surface of the rotating member to remove the charge from the rotating member. Therefore, since the residual charge on the outer peripheral surface of the rotating member and its increase can be eliminated, high quality printing can be performed continuously and stably while each printing medium is reliably and stably adsorbed and held.

According to a second aspect of the present invention, there is provided an ink jet printer in which a medium supply means, a charging means, a medium peeling means, a print head, and a charge removing means are arranged in this order in the rotation direction of the rotating member.

In this invention, since the medium supply means is provided on the upstream side of the charging means in the rotation direction of the rotating member, the supplied printing medium can be charged immediately, so that the charging efficiency is high. Further, since the medium separating means is provided on the downstream side, the previous print medium can be smoothly separated and the next print medium can be supplied promptly. Further, since the static elimination means is provided on the downstream side of the print head, static elimination of the rotating member can be performed immediately after the print medium has passed after printing. Therefore, the same operation and effect as those of the first aspect of the invention can be obtained, and further, from the previous supply to the subsequent peeling, mainly focusing on the charging, can be performed continuously and more stably.

According to a third aspect of the present invention, the charging means is formed of a charging roller rotatable against the outer peripheral surface and the leading end of the printing medium supplied by the medium supplying means and the outer peripheral surface are first formed. An inkjet printer is provided downstream of a position on the outer peripheral surface in contact with the rotating member in a rotation direction of the rotating member.

According to this invention, when the leading end of the print medium supplied from the medium supply means first comes into contact with or reaches the outer peripheral surface of the rotating member, the charging roller disposed downstream of the reaching point in the rotating direction of the rotating member. Are charged and rotated while being pressed against the print medium. Therefore, in addition to providing the same operation and effect as the case of the second aspect of the present invention, the leading end of the supplied print medium can be immediately and reliably charged, so that more stable suction holding and rotational transfer can be performed.

Further, according to a fourth aspect of the present invention, the charging roller is formed of a conductive rubber roller having an electric resistance value of 1 × 10 ⁶ Ω-cm or less, and has a DC 1.5
This is an ink jet printer which is formed so that a printing medium contacted by applying KV can be charged.

In this invention, the electric resistance value is 1 × 10 ⁶
Direct current (D) is applied to the rotating shaft of the conductive rubber roller of Ω-cm or less.
C) The printing medium is charged by applying 1.5 kV. Therefore, the same operation and effect as those of the inventions of claims 2 and 3 can be obtained, and the printing medium can be more closely adhered to the outer peripheral surface and the charging efficiency can be further improved.

Further, the invention according to claim 5 is an ink jet printer wherein the charging means and the charge removing means are formed on the outer peripheral surface of the rotating member so as to be able to contact and separate therefrom.

In this invention, the charging means is in contact with the outer peripheral surface immediately before the print medium is supplied, and can be separated after charging over the entire length of the print medium. Contact during a period that is not held, and can be separated during holding. Therefore, the same operation and effect as those of the inventions according to the second to fourth aspects can be obtained, and furthermore, since there is no interference with the printing medium or the like during the printing operation, smooth charging and discharging can be performed.

Further, according to the invention of claim 6, the static eliminator is capable of continuously contacting the outer peripheral surface during one rotation of the rotating member in a state where the printing medium is not suction-held on the outer peripheral surface of the rotating member. Is an inkjet printer.

According to this aspect of the invention, static electricity can be continuously removed during one rotation of the rotating member in a state where the printing medium is not held by suction.
Therefore, the same operation and effect as those of the inventions of claims 2 to 5 can be obtained, and furthermore, the entire outer peripheral surface of the rotating member can be more reliably and uniformly discharged.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. This inkjet printer is shown in FIG.
As shown in the figure, the print medium M is sucked and held on the outer peripheral surface 11 (12) of the rotating member 10 rotatable at a constant peripheral speed by using the charge attracting force, and the ink jet nozzle is attached to the print medium M rotating with the rotating member 10. The printing member 207 is formed so as to be capable of printing while spraying ink, and is formed so as to be able to contact the outer peripheral surface 11 (12) before suction holding of the printing medium M and / or after printing so that the rotating member 10 can be neutralized.

A description will be given of a case where the overall configuration is the same as that of the previously proposed ink jet printer (FIG. 4). However, the description of the same parts as those in FIG. 4 will be simplified or omitted.

In FIG. 1, the rotating member is formed of a drum 10 having a hollow portion 14, and is rotatable at 120 rpm capable of achieving multi-color printing at 20 PPM. The shaft portion 15 serving as the center of rotation is grounded by a ground wire 19 (open space).
It is connected to the.

On the outer peripheral surface 11 of the drum 10, an electric insulating layer 12 having an electric resistance value (volume resistivity) of 1 × 10 ¹² to 1 × 10 ²⁰ Ω-cm is formed. This is to secure a surface potential (for example, 500 V or more) after charging. In this embodiment, the thickness 2 is closely adhered to the drum outer peripheral surface 11.
It is formed from a 5 μm Mylar sheet. In addition, a recess 13 is provided in a part of the outer peripheral surface 11 so that the tip of the medium peeling means (peeling claw) 140 can temporarily enter therein.

Around the drum 10, a medium supply means 90, a charging means 21 and a replenishment charging means 25 forming a medium holding means 20, a charge eliminating means 30, a medium peeling means 140, a nozzle (print) head 200 The static elimination means 40 is arranged in this order from the upstream side to the downstream side in the rotation (Y) direction.

The medium supply means 90 includes a pair of supply rollers 9.
In addition to the medium supply function to the drum 10
It has a function of adjusting the attitude of the print medium M and a function of standby for supply.

That is, the leading end of the printing medium M fed from below in FIG.
3 and is elastically deformed in the guide 94 on the upstream side. Therefore, the leading end of the print medium M is placed on the drum (shaft 1).
5) It can be supplied without skew because it is aligned in the axial direction.
The elastic restoring force of the print medium M in the guide 94 can promote the posture adjusting force. Whether or not the posture adjustment process has been started can be confirmed by the medium sensor 97.

When the posture adjustment is completed, both rollers 9
Reference numerals 1 and 92 move the print medium M to the drum 10 side along the downstream guide 96 until the leading end of the print medium M is detected by the medium sensor 98. Therefore, the leading end of the printing medium M is bitten by the rollers 91 and 92, so that the trailing end of the printing medium M is fed to the cassette feeding means (71) or the manual feeding means disposed below the guide 94. It can be free from (61). That is,
At this point, the feeding process for the next print medium M is completed.
Thus, the supply standby state to the drum 10 can be established. This is effective for speeding up printing.

The printing medium M can be supplied to the drum 10 (11) at a predetermined timing. The position where the supplied print medium M first contacts, that is, the outer peripheral surface 11
(12) Let P be the destination point on the top. The supplied print medium M
After the leading end of the roller 91 is
Is moved rightward as shown by the two-dot chain line in FIG. Therefore, the rear end side of the print medium M becomes free, and does not become a load of the rotation transfer by the drum 10.

The charging means 21 may be either a direct (contact) charging method using a charging roller or the like or an indirect (non-contact) charging method using a corona discharger or the like in relation to the charge removing means 40. And

That is, the charging means 21 can be selectively switched between the solid line state (contact) and the two-dot chain line state (separation) shown in FIG. 1 by the advance / retreat means 29 shown in FIGS. In the printing medium M (or the electrically insulating layer 1)
2) a charging roller 23 that can be directly charged; and a power supply 22 that applies, for example, DC + 1.5 kV to the charging roller 23. The charging roller 23 is a conductive rubber roller having an electric resistance value (volume resistivity) of 1 × 10 ⁶ Ω-cm or less. Improve charging efficiency and pressure contact. The conductive rubber is selected from urethane rubber, silicon rubber and the like. In this embodiment, urethane rubber is employed.

The charging roller 23 is disposed on the outer peripheral surface 11 of the charging roller 23 immediately downstream of the arrival point P on the downstream side in the rotation (Y) direction of the drum 10.
(12) is provided as a position that can be contacted. That is,
The angle θ between the reaching point P about the shaft portion (center of rotation) 15 and the charging roller 23 is made smaller as long as the leading end of the supplied print medium M does not collide with the charging roller 23. This is because the leading end of the supplied print medium M can be quickly charged. When the leading end of the print medium M is more reliably sucked and held on the outer peripheral surface 11 (12), the rotational transfer can be more reliably performed.

The replenishing charging means 25 which forms the medium holding means 20 together with the charging means 21 is formed of a corona discharger which can discharge a positive charge by applying, for example, 4 kV, and rotates the drum 10 (especially, the nozzle head). In order to maintain a constant charge attraction force by compensating for the charge attraction force attenuated during printing using the printing medium 200, the charge is replenished to the print medium M.

As shown in FIG. 2, the advancing / retreating means 29 includes a link lever 29L that can rotate around a pin member 29P,
A spring 29SP for pulling one side (upper side) 29LF of the link lever 29L to the left in the drawing, and an eccentric cam 29C for pressing the other side (lower side) 29LB downward in the figure against the pulling force of the spring 29SP. Consists of The charging roller 23 is rotatably mounted on a link lever 29L via a support shaft 29S.

Therefore, the other side 29
When the LB is not pushed down, the spring 29
The charging roller 23 can be brought into contact with the drum outer peripheral surface 11 (12) or the print medium M by the urging force (tensile force) of the SP. In addition, they come into contact with a certain pressing force. If the other end 29LB is pushed down by the eccentric cam 29C, the charging roller 23 can be separated from the drum outer peripheral surface 11 (12).

The advance / retreat means 29 is moved forward and backward by a drive control unit 250 described later. At least advance is performed at a timing at which the leading end of the print medium M can be charged immediately after the charging roller 23 comes into contact with the outer peripheral surface 11 (12).

The charge eliminating means 30 is formed of a corona discharger to which an AC potential can be applied. Prior to the mechanical peeling by the medium peeling means 140, the charge eliminating means 30 is provided between the outer peripheral surface 11 (12) and the print medium M. The charge adsorption force can be eliminated. The replenishment charging means 25 is based on reverse charging.

Here, the static elimination means 40 includes a static elimination brush 42
The outer peripheral surface 11 (specifically, the electric insulating layer 1
2) It is formed so as to be able to remove the charge remaining in contact therewith. The neutralization brush 42 is attached to the elevating means 59 shown in FIG. 3 via the holder 41 and the elevating member 45, and is formed so as to be able to move up and down between a lower position and an upper position shown in FIG.

The elevating means 59 may be appropriately constructed from a cam driving method similar to the moving means 29, such as a solenoid driving method, an air cylinder driving method, or a motor driving method.

The drive control unit 250 shown in FIG.
Although the entire printer including the ROM and the RAM can be drive-controlled, those not directly related to the apparatus are not shown.

In the case of this embodiment, the drive control unit 250
When the apparatus power is turned on (ON), the main motor 10M is rotated at a low speed and the elevating means 59 is raised from the lower position to the upper position shown in FIG. Accordingly, the charge removing brush 42 comes into contact with the electric insulating layer 12 to remove the residual charge on the drum 10 side. This initialization is completed by an automatic or manual command.

When the initialization is completed, the drive control section 250 drives the lifting / lowering means 59 to lower it to a position below the static elimination means 40, and switches the main motor 10M to high-speed rotation.

Thereafter, the drum rotation position detector 10S
When it is detected that the rotational position (angle) of the drum 10 has reached a preset rotational position, the print medium M that has been in the supply standby state by driving the medium supply unit 90 is shown in FIG. It is supplied to the side 10 at a moving speed equivalent to the drum peripheral speed.

Prior to this (or simultaneously), the advance / retreat means 29 is driven to advance the charging roller 23 from the two-dot chain line state to the solid line state in FIG. In other words, the process is executed immediately before the arrival point P is rotationally transferred. Charging roller 2
3 contacts the drum outer peripheral surface 11 (electrical insulating layer 12) with a constant pressing force by the urging force (tensile force) of the spring 29SP shown in FIG. The drive control unit 250 turns on the power supply 22 immediately before or simultaneously with contact with the print medium M, and applies a voltage to the charging roller 23.

Therefore, from the point in time when the leading end (the arrival point P) of the supplied print medium M enters between the charging roller 23 and the electrical insulating layer 12 that rotates following the rotation of the drum 10, the print medium M Can be charged. That is,
A charge is applied to the leading end of the print medium M, and the charge can be immediately attracted and held on the outer peripheral surface 11 (12) of the rotating member (10) by the charge attracting force.

When the holding of the leading end is established, in this embodiment, when it is confirmed from the output signal of the drum rotation position detector 10S, the drive control unit 250 moves the one roller 91 of the medium supply means 90 to the two points in FIG. Move to dashed line state. Therefore, the rear end side of the print medium M is in a free state from both rollers 91 and 92, so that the rotation transfer load of the drum 10 is not generated.

Thus, the printing medium M is charged on the outer peripheral surface 11 of the drum by the charge attracting force given by the charging means 21.
(Electrical insulating layer 12) and is held by suction and charging roller 23
And is transported in the Y direction as the drum 10 rotates. Since the charging roller 23 is driven to rotate and presses the printing medium M from the front end side to the rear end side while pressing against the outer peripheral surface 11 (12) side, the adhesion between the printing medium M and the electrical insulating layer 12 is improved. Can be improved.

When the drum rotation position detector 10S detects (confirms) that the rear end of the printing medium M has passed the charging roller 21 during one rotation of the drum 10, the charging roller 21 moves forward and backward. 29, the print medium M (ST19) is retracted to the two-dot chain line state in FIG.
Side). Therefore, the print medium M is attracted and held on the drum outer peripheral surface 11 (12) only by the electric charge attracting force, and is rotationally transferred in the Y direction.

The ink is jetted from the nozzle head (inkjet nozzle) 200 during the rotation of the drum 4 (2 to 5) thereafter, and printing is performed on the print medium M which is being rotationally transferred. During this period, the charging means 25 for replenishment operates, and the charge attraction force is kept constant. In addition, the drive control unit 250 activates the medium supply unit 90 to set the next print medium M in a supply standby state.

When the multi-color printing on the print medium M of, for example, A4 size is completed by four rotations of the drum, the drive control unit 250
Operates the charge eliminating means 30 to eliminate the charge adsorbing force between the printed printing medium M and the electrical insulating layer 12, and activates the medium peeling means 140 to mechanically move the leading end side of the printed printing medium M. Peel off. The peeled print medium M is
The medium is delivered to the medium discharge / conveying means (160) by a medium peeling means (peeling claw) 140 which also serves as a delivering means.

Thus, the drive control unit 250 controls the lifting / lowering unit 5 to suck and hold the next print medium M and to rotate and transport the print medium M.
9 is driven to raise the charge removing means 40 to the upper position as shown in FIG. Therefore, the charge removing brush 42 removes the charge remaining on the electric insulating layer 12.

The outer peripheral surface 11 (12) of the drum 10
In a state where the printing medium M is not held by suction
During one rotation (during the sixth rotation in this embodiment), the electrical insulating layer 12 is in continuous contact. Therefore, it is possible to uniformly and reliably remove the static electricity in the entire longitudinal direction of the outer peripheral surface 11 (12).

Hereinafter, printing is performed while the print medium M is successively suction-held and rotated and transferred. When the printing operation is completed, the drive control unit 250 rotates the main motor 10M again at a low speed and activates the lifting / lowering means 59 to move the neutralization brush 42 in FIG.
(ST26), and the charge is also removed at the end of the printing operation. This is executed for a preset time Ts. Thereafter, the charge removing brush 42 is lowered to the lower position.

According to this embodiment, the print medium M is attracted and held on the outer peripheral surface 11 (12) of the rotating member 10 rotatable at a constant peripheral speed by using the charge attracting force. The ink is sprayed from the ink jet nozzle 207 onto the rotating print medium M so as to be printable, and the rotary member 10 is discharged by contacting the outer peripheral surface 11 (12) before and / or after the suction of the print medium M and / or after printing. Since the printing medium M is formed so as to be rotatable,
0) It is possible to stably perform high-quality printing while securely and stably holding by suction.

The medium supply means 90, the charging means 20 (23) and the medium peeling means 1 are rotated in the direction of rotation of the rotating member (10).
Since the print head 40, the print head (200), and the charge removing means 40 are arranged in this order, the process from the previous supply centering on the charging to the subsequent peeling can be performed continuously and more stably.

The charging means 21 is provided on the outer peripheral surface 11 (12).
Is formed from a charging roller 23 that can be pressed against and rotated from the position (P) on the outer peripheral surface where the leading end of the print medium M supplied by the medium supply unit 90 and the outer peripheral surface 11 (12) first contact. Since it is disposed downstream of the member (10) in the rotation (Y) direction, the leading end of the supplied print medium M can be immediately charged, so that more stable suction holding and rotation transfer can be performed.

The charging roller 23 has an electric resistance of 1 ×.
Since the printing medium M is formed of a conductive urethane rubber roller having a resistance of 10 ⁶ Ω-cm or less and is contacted by applying a direct current of 1.5 KV through its rotating shaft, the printing medium M is formed so as to be chargeable. Can be brought into close contact with the outer peripheral surface 11 (12), and the charging efficiency can be further enhanced.

Further, since the charging means 21 (23) and the charge removing means 40 are formed so as to be able to contact and separate from the outer peripheral surface 11 (12) of the rotating member (10), they interfere with the printing medium M during the printing operation. Smooth charging and static elimination can be performed without any.

In a state where the printing medium M is not adsorbed and held on the outer peripheral surface 11 (12) of the rotating member (10), the discharging member 40 rotates the outer peripheral surface 11 during one rotation of the rotating member (10).
Since it is possible to make continuous contact with (12), the entire outer peripheral surface 11 (12) of the rotating member (10) can be more reliably and uniformly discharged.

Further, since the charging roller 23 is formed to be rotatable following the rotation of the drum 10, the rotating member (1
In addition to not applying unnecessary external force that causes the wrinkle or the like to the print medium M without causing the rotation load of 0), the drum outer peripheral surface 11 (1) can be drawn from the front end side to the rear end side.
Adhesion to 2) can be further enhanced.

Further, since the charging roller 23 can be pressed against the drum outer peripheral surface 11 (12) by the urging force (tensile force) of the spring 29SP when the advance / retreat means 29 is in the advanced state, the printing medium M Outer peripheral surface 11 (1
Adhesion to 2) can be further enhanced.

Further, since the medium supply means 90 has a posture adjustment function and a supply standby function in addition to the medium supply function, the print medium M can be supplied and held on the drum 10 without skew. At the same time, the feeding process for the next print medium M can be completed during the printing operation of the previous print medium M, so that the speed of the holding rotation transfer and the printing can be further increased.

Further, replenishing charging means 25 is provided,
Since the charge adsorption force attenuated during the holding rotation transfer and during printing is formed so as to be replenished, the holding rotation transfer can be more reliably performed.

Further, a charge eliminating means 30 is provided,
After the holding rotation transfer (printing operation), the charging means 20 (21, 21)
Since it is formed so that the charge adsorbing force according to 5) can be eliminated, mechanical peeling (holding release) by the medium peeling means 140 is performed.
Can be smoothed.

[0071]

According to the first aspect of the present invention, the print medium is attracted and held on the outer peripheral surface of the rotatable member rotatable at a constant peripheral speed by using the electric charge attracting force, and is applied to the print medium rotating with the rotatable member. It is formed to be printable while spraying ink from an ink jet nozzle, and before and / or after holding a print medium by suction.
Alternatively, since the rotating member is formed so as to be capable of discharging electricity by contacting the outer peripheral surface after printing, residual charges on the outer peripheral surface of the rotating member and its increase can be eliminated. Therefore, high-quality printing can be performed continuously and stably while securely and stably holding each printing medium.

According to the second aspect of the present invention, the medium supply means, the charging means, the medium peeling means, the print head and the charge removing means are arranged in this order in the rotation direction of the rotating member. In addition to the same effects as those of the first invention,
Further, the process from the previous supply centering on charging to the subsequent peeling can be performed continuously and more stably.

According to the third aspect of the present invention, the charging means is formed of a charging roller rotatable against the outer peripheral surface, and the leading end of the printing medium supplied by the medium supplying means first comes into contact with the outer peripheral surface. Since it is arranged downstream of the position on the outer peripheral surface in the rotation direction of the rotating member,
In addition to the effects similar to those of the invention of the third aspect, the leading end of the supplied print medium can be immediately charged, so that more stable suction holding and rotational transfer can be performed.

Further, according to the fourth aspect of the present invention, the charging roller is formed of a conductive rubber roller having an electric resistance value of 1 × 10 ⁶ Ω-cm or less, and has a direct current of 1.times.
Since the printing medium contacted by applying 5 KV is formed so as to be chargeable, the same effects as those of the inventions of claims 2 and 3 can be obtained, and the printing medium can be more closely attached to the outer peripheral surface. The charging efficiency can be further increased.

Further, according to the fifth aspect of the present invention, the charging means and the static elimination means are formed on the outer peripheral surface of the rotating member so as to be able to come into contact with and separate from each other. In addition to the above advantages, the present invention does not interfere with a printing medium or the like during a printing operation, so that smooth charging and discharging can be performed.

Further, according to the present invention, the discharging means can be continuously contacted with the outer peripheral surface during one rotation of the rotating member in a state where the printing medium is not suction-held on the outer peripheral surface of the rotating member. Therefore, the same effects as those of the inventions of claims 2 to 5 can be obtained, and furthermore, the entire outer peripheral surface of the rotating member can be more reliably and uniformly discharged.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is also a view for explaining an advance / retreat means.

FIG. 3 is a block diagram for explaining a drive control unit.

FIG. 4 is a diagram for explaining a previously proposed inkjet printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Drum (rotating member) 11 Outer peripheral surface 12 Electric insulating layer (outer peripheral surface) 15 Shaft part 20 Medium holding means 21 Charging means 22 Power supply 23 Charging roller 25 Replenishment charging means 29 Advance / retreat means 30 Charge erasure means 40 Static elimination means 42 Static elimination brush 59 Elevating means 90 Medium supply means 140 Medium peeling means 200 Nozzle head (print head) 207 Inkjet nozzle M Print medium Y Rotation direction

Claims (6)

[Claims] A print medium is attracted and held on an outer peripheral surface of a rotatable member rotatable at a constant peripheral speed by using a charge attracting force, and printing is performed by spraying ink from an inkjet nozzle onto a rotating print medium with the rotatable member. An ink jet printer, wherein the rotary member is formed so as to be able to contact the outer peripheral surface before and / or after printing of the print medium by suction and / or after printing, so that the rotating member can be neutralized. 2. The ink jet printer according to claim 1, wherein a medium supply unit, a charging unit, a medium separation unit, a print head, and a charge removal unit are arranged in this order in the rotation direction of the rotating member. 3. A position on the outer peripheral surface at which the leading end of the print medium supplied by the medium supply unit and the outer peripheral surface first contact each other, wherein the charging means is formed of a charging roller rotatable in pressure contact with the outer peripheral surface. 3. The ink jet printer according to claim 2, wherein the ink jet printer is disposed downstream of the rotating member in the rotation direction. 4. The charging roller has an electric resistance value of 1 × 10.
3. A printing medium formed of a conductive rubber roller having a resistance of ⁶ .OMEGA.-cm or less and capable of charging a contacted printing medium by applying a direct current of 1.5 KV via a rotating shaft thereof.
Or the inkjet printer according to claim 3. 5. The ink jet printer according to claim 2, wherein the charging unit and the discharging unit are formed on the outer peripheral surface of the rotating member so as to be able to contact and separate therefrom. 6. The apparatus according to claim 2, wherein said discharging means is capable of continuously contacting the outer peripheral surface during one rotation of the rotating member in a state where the printing medium is not suction-held on the outer peripheral surface of the rotating member.
An ink jet printer according to any one of claims 1 to 5.