JPH10193720A - Medium holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a medium surely and stably on a rotary member. SOLUTION: The medium holder comprises a charging means 20 (corona discharger 21) for imparting charges to the medium holding face Mb of a rotary member (drum 10) turning in one (Y) direction at a constant speed without touching before the forward end of an externally fed medium (print medium M) touches the outer circumferential surface 11 of the rotary member, and a supplementary charging means 22 for supplementing the charge attraction force, being damped through rotation, of the medium suction held on the outer circumferential surface 11 of the rotary member through the charge attraction force of the charging means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a medium holding device for holding a medium on an outer peripheral surface of a rotatable rotating member by utilizing a charge attracting force. In particular, it is used for holding a print medium of an ink jet printer.

[0002]

2. Description of the Related Art For example, a nozzle unit for each color is reciprocated over the entire length in the line direction, and printing is performed during each forward movement to print one line, and after printing one line, a printing medium (plain paper, OH) is printed.
Compared to a so-called serial-type ink jet printer that feeds M one line in the column direction and repeats them, printing speed can be greatly increased, continuous printing operation can be performed over many sheets, and so-called laser printing. The present applicant has proposed an ink jet printer capable of achieving a significant reduction in size as compared with a printer (for example, Japanese Patent Application No. 8-296959).
No.).

That is, in FIG. 5, a drum 10 is rotatable at a constant peripheral speed and can hold a print medium M on an outer peripheral surface 11 thereof. Rotation of this drum 10 (Y)
A nozzle unit (print head) 200 for each color is provided in the direction. Therefore, an integrated nozzle unit 200 for each color in the entire length in the row direction (perpendicular to the paper surface) or an integrated nozzle unit 200 for each color in which a plurality of nozzle unit elements are arranged in the row direction is provided, 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.

[0004] Further, since the nozzle unit 200 for each color and the ink tank (ink cassette) 213 for each color are arranged at a distance from each other, the nozzle unit 2 for each color is provided.
00 can be lightened, and the reciprocating movement speed in the row direction can be greatly increased. This further promotes higher printing speed, and the capacity of the ink tank (ink cassette) 213 for each color can be greatly increased. Can be continuously printed.

In order to realize these, a medium feeding means 60 and a medium feeding means 90 are provided on one side (right side in FIG. 5) of the drum 10, and a medium is provided on the other side (left side in FIG. 5). Peeling means 140, medium discharging / conveying means 160, and direction switching means 1
90 are provided.

The medium feeding means 60 includes a cassette feeding means 7
The print medium M can be selectively fed one sheet at a time from either one of the manual feeding means 61 and the manual feeding means 61. Medium supply means 90
Supplies the fed print medium M to the drum 10 at a predetermined timing. The medium peeling means 140 peels the print medium M from the drum 10 after printing, and the medium discharge / transport means 160 discharges and transports the peeled print medium M leftward in FIG. The direction switching unit 190 selectively switches between the discharge tray 192 and the upper discharge tray 193.

In this manner, since the feeding, supply, holding, printing, peeling, and discharging and conveying of the print medium M can be continuously performed, multicolor printing of, for example, 20 sheets or more in A4 size can be performed in one minute. That is, if the print medium M is rotated and held on the rotating drum 10 using the medium holding device, high-speed printing becomes possible.

Here, it is conceivable that the medium holding device is constructed by utilizing any one or an arbitrary combination of a charge attracting force, a negative pressure attracting force, and a mechanical clamping force. The adoption of a charging means utilizing an attraction force is effective.

[0009]

By the way, the charging means is provided by any one or a combination of a contact system in which the medium is directly charged by contact with the medium and a non-contact system in which the medium is indirectly charged (charged) by non-contact with the medium. Be built.

In general, the contact method can charge the medium directly, so that the charging efficiency is high, and the medium can be pressed against the outer peripheral surface of the rotating member, so that the mechanical adhesion can be provided. On the other hand, since the non-contact method is indirect charging, it is possible to avoid interference with components including a medium to be held and a rotating member, but it is said that charging efficiency is relatively low.

However, as the number of types of media to be used increases with the spread of the media, especially when there is a thick media, the contact charging system is charged by contact from the surface opposite to the holding surface to the rotating member. In some cases, the substantial charging efficiency for obtaining the force is not always high. Also,
In the case where the negative pressure suction holding and the mechanical suction holding are used together as an auxiliary, a measure for avoiding interference with those embodied elements is required. Naturally, there is also a problem in the sequence that charging cannot be performed until a medium is supplied.

Further, in any of the charging methods, there is a phenomenon that the charge attracting force is attenuated by other factors (for example, printing) during the rotation of the rotating member.

SUMMARY OF THE INVENTION An object of the present invention is to provide a medium holding device capable of applying a charge to a medium in a non-contact manner and replenishing an attenuated charge adsorbing force so as to reliably and stably hold the medium.

[0014]

According to a first aspect of the present invention, a rotating member which rotates at a constant peripheral speed in one direction does not contact the rotating member before the leading end of a medium supplied from the outside comes into contact with the outer surface. And a replenishing charging means capable of replenishing the charge adsorbed force attenuated during rotation to the medium adsorbed and held on the outer peripheral surface of the rotating member by the charge adsorbing force of the charging means. Device.

In the above invention, the charging means charges the rotating rotating member in a non-contact manner and applies a charge. Therefore, when the medium supplied from the outside can come into contact with the rotating member,
The holding surface of the medium is held on the outer peripheral surface by the electric charge attracting force between the rotating member. Also, during rotation after holding,
For example, the charge attraction force attenuated by ink jet printing is kept constant by the supplementary charge from the supplementary charging means. Therefore, since the holding surface is charged, the charging efficiency is substantially high, and for example, even if the medium is thick, it can be held reliably and stably.

Further, according to a second aspect of the present invention, the outer peripheral surface of the rotating member has an electric resistance value of 1 × 10 ¹² to 1 × 10 ²⁰ Ω-cm.
A medium holding device formed of a corona discharger that forms an electric insulating layer of the above, short-circuits the rotating shaft to ground, and the charging means applies a positive charge to the electric insulating layer.

In this invention, a positive charge is applied from the corona discharger to the high-resistance electrical insulating layer formed on the outer peripheral surface of the rotating member whose rotating shaft is short-circuited to ground. Therefore, the same operation and effect as those of the first aspect can be obtained, and the substantial charging efficiency can be further improved.

The invention according to claim 3 is a medium holding device in which the charging means and the replenishment charging means are formed from a common corona discharger having a variable charging polarity.

In this invention, the medium is attracted and held while the rotating member is charged by the common corona discharger. Thereafter, the charge polarity is switched to replenish the medium with, for example, an amount of charge corresponding to the amount of attenuation. Therefore, the same operation and effect as those of the first and second aspects of the invention can be obtained, and further, the size and cost of the apparatus can be reduced.

Further, according to a fourth aspect of the present invention, there is provided an electrically insulating roller capable of pressing the medium against the outer peripheral surface of the rotating member after the leading end of a medium supplied from the outside comes into contact with the outer peripheral surface of the rotating member. Media holding device.

In this invention, when the leading end of the medium comes into contact with the outer peripheral surface, the electrically insulating roller presses the medium toward the outer peripheral surface. Therefore, the same effects as those of the first to third aspects of the present invention can be obtained, and further, since the medium can be brought into close contact with the outer peripheral surface, the holding by the charge adsorption force can be further strengthened, and the electric insulating roller can be used. Since the medium can be mechanically squeezed from the front end side to the rear end side, the entire area of the medium can be uniformly held and wrinkles and the like can be prevented.

Further, the invention according to claim 5 is a medium holding device in which the electrically insulating roller is formed so as to be capable of coming into contact with and separating from the medium held by the rotating member.

According to the invention, the electrically insulating roller in contact with the medium is separated from the rotating member when the rear end of the medium passes, for example. Therefore, the same operation and effect as those of the fourth aspect of the invention can be obtained, and further, the interference of the electrically insulating roller with the medium and other components can be avoided.

Further, the invention according to claim 6 is a medium holding device provided with a charge removing means for removing a charge adsorbing force for adsorbing and holding a medium on an outer peripheral surface of the rotating member.

In this invention, the charge removing means removes the charge attraction before the medium is peeled off. Therefore,
In addition to providing the same functions and effects as those of the first to fifth aspects of the present invention, the medium can be easily separated after holding.

Furthermore, in the invention according to claim 7, a medium separating means capable of mechanically separating the medium from the outer peripheral surface thereof is provided downstream of the disposing position of the charge removing means in the rotation direction of the rotating member. Media holding device.

In this invention, when the charge removing means removes the charge attracting force, the medium peeling means disposed downstream in the rotating direction immediately peels the medium from the outer peripheral surface, for example, mechanically. Therefore, the same operation and effect as the case of the invention of claim 6 can be obtained, and further, the peeling can be performed smoothly and quickly in a series.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) As shown in FIG. 1, a medium (printing medium) supplied from the outside to an outer peripheral surface 11 of a rotating member (drum 10) rotating at a constant peripheral speed in one (Y) direction as shown in FIG. Before the leading end of the medium M) comes into contact with the rotating member (1),
0) charging means 20 (21) capable of applying a charge without contact
And a replenishment charging means (22) capable of replenishing the charge adsorption force attenuated during rotation on the medium held on the outer peripheral surface 11 (12) of the rotating member by the charge adsorption force of the charging means.

The overall configuration will be described for the case where it is constructed so that it can be used as a medium holding means of the same inkjet printer as that of the previously proposed inkjet printer (FIG. 5). Therefore, the description of the same parts as those in FIG. 5 will be simplified or omitted.

In FIG. 1, the rotating member is formed of a drum 10 having a hollow portion 14, is capable of achieving multi-color printing at 20 PPM, and is rotatable in the Y (one) direction at a constant peripheral speed of 120 rpm. The shaft portion (rotating shaft) 15 serving as the center of rotation is short-circuited to ground (open space) by a ground wire 19.

On the outer peripheral surface 11 of the drum 10, an electric insulating layer 12 having an electric resistance value of 1 × 10 ¹² to 1 × 10 ²⁰ Ω-cm is formed. In this embodiment, the drum outer peripheral surface 11
It is formed from a mylar (polyester film) sheet having a thickness of 25 μm, which is adhered to the substrate. Also, the outer peripheral surface 1
Part 1 is provided with a recess 13 into which the tip of a medium peeling means (peeling claw) 140 can temporarily enter.

Around the drum 10, charging means 20
Corona discharger 21, medium supply means 90, electrically insulating roller 30, replenishment charging means (corona discharger 2
2), static eliminating means (corona discharger 40), medium peeling means 1
40, a nozzle (printing) head 200 is arranged in this order from the upstream side to the downstream side in the rotation (Y) direction.

Here, as shown in FIG. 1, the corona discharger 21 forming the charging means 20 is provided on the front side (in FIG. 1) of the medium supply means 90 for supplying the print medium M to the drum 10 in the direction of rotation (Y) of the drum. (A left side), and before the leading end of a medium (print medium M) supplied from the outside (90 side) comes into contact with the outer peripheral surface 11 of the drum 10, the drum 10 [11 (1
2)], a positive charge Q can be provided in a non-contact manner.

That is, a positive charge Q is applied to the surface of the high-resistance electrical insulating layer 12, and a negative charge (static induction) is applied to the holding surface (back surface) Mb of the print medium M supplied from the outside (91 side). ) Occurs and a charge attraction force can be generated between the drum 10 (12). Therefore, depending on the thickness of the print medium M, the substantial charging efficiency for generating the charge attracting force can be further improved as compared with the case where the non-holding surface (front surface ... printing surface) Mf is directly charged by contact.

Further, it does not interfere with the print medium M and the peripheral components (90, 30, 22, 40, 140, etc.) held by the electric charge, and furthermore, for example, the extremely short time between the supply timing with the medium supply means 90 and Since there is no need to perform temporal sequence adjustment, control can be facilitated.

Corona discharger 2 forming charging means for replenishment
Numeral 2 replenishes the medium (M), which has been charged and held on the outer peripheral surface 11 (12) of the rotating member (10), by the charge adsorption force of the corona discharger 21, with the charge adsorption force attenuated during rotation.
In this embodiment, since the replenishing charging means also charges the medium (M) in a non-contact manner, the charging is performed from the surface Mf side of the medium (M).

That is, the corona discharger 22 forming the replenishing charging means discharges negative charges by applying, for example, -4 (+2, -2) kV and rotates the drum 10 (especially when the nozzle head 200 is turned on). The constant charge attraction force is maintained by compensating for the charge attraction force attenuated during printing.

The medium supply means 90 includes a pair of supply (aligning) rollers 91 and 92, and has a function of adjusting the attitude of the print medium M and a function of supplying the medium in addition to the function of supplying the medium to the drum 10.

That is, the leading end of the printing medium (medium) M fed from below in FIG.
2 and is elastically deformed in the guide 94 on the upstream side. Therefore, the leading end of the print medium M is aligned with the axial direction of the drum (shaft portion 15) and can be supplied without skew. 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 attitude adjustment is completed, the supply rollers 91 and 92 are connected to the medium sensor 98 by the leading end of the print medium M.
The print medium M is moved to the drum 10 side along the downstream side guide 96 until the position detected by. Therefore,
Since the leading end side of the printing medium M is bitten by the rollers 91 and 92, the trailing end side of the printing medium M is connected to the cassette feeding means (71) or the manual feeding means (61) disposed below the guide 94. ) Can be free. In other words, at this point, the feeding process for the next printing medium M is completed, and a 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
Is held on the outer peripheral surface 11 by, for example, negative pressure suction holding means (not shown) provided as necessary,
On the other hand, the supply roller 91 is moved rightward as shown by a two-dot chain line in FIG. 1 by the engagement / separation means 95 shown in FIG.
Therefore, the rear end side of the print medium M becomes free,
No load is imposed on the rotary transfer by the drum 10. The engagement / separation means 95 is formed in the same manner as the contact / separation means 29 described later in detail.

After the leading end of the medium (M) supplied from the outside (90) contacts the outer peripheral surface 11 (12) of the drum 10, the electrically insulating roller 30 applies the medium (M) to the outer peripheral surface 1 (12).
1 (12) side. Further, although it is possible to follow the rotation of the drum 10, it may be formed to be able to rotate.

The electrically insulating roller 30 can be selectively switched between a solid line state (contact) and a two-dot chain line state (separation) shown in FIG. 1 by the contact / separation means 29 shown in FIG. In this embodiment, the rubber hardness is set to 20 ± 5 degrees (JIS A scale), and the nip width N can be increased. Therefore, the adhesion by pressing can be improved.

The electrically insulating roller 30 is used for the drum 10
It is arranged as a position where it can come into contact with its outer peripheral surface 11 (12) immediately after the arrival point P on the downstream side in the rotation (Y) direction. That is, the leading end of the supplied print medium M is positioned at the outer peripheral surface 11 (1).
As far as it does not collide with the electrically insulating roller 30 contacted in 2), it is arranged closer. This is because the leading end of the supplied print medium M can be quickly pressed. 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.

As shown in FIG. 2, the contact / separation means 29 includes a link lever 29L rotatable about a pin member 29P and a spring for pulling one side (upper side) 29LF of the link lever 29L to the left in the figure. 29SP and an eccentric cam 29C for pushing the other side (lower side) 29LB downward in the figure against the pulling force of the spring 29SP. The electrically insulating roller 30 is connected to the link lever 29 via the support shaft 29S.
L is mounted rotatably, that is, rotatably (rotatable) following the rotation of the rotating member (10).

Therefore, the other side 29
When the LB is not pushed down, the spring 29
By the urging force (tensile force) of the SP, the electrically insulating roller 3
0 can be brought into contact with the printing medium M through the drum outer peripheral surface 11 (12). In addition, they come into contact with a certain pressing force. When the other end 29LB is pushed down by the eccentric cam 29C, the electrically insulating roller 30 is moved to the drum outer peripheral surface 11 (1).
2).

The contact / separation means 29 is advanced (contacted) and retracted (separated) by the drive control unit 250 described later. At least when the medium (M) is moved forward,
It is desirable to be executed at the timing immediately after the contact with (12).

The charge removing means is formed by a corona discharger 40 to which an AC potential can be applied. Prior to the mechanical peeling by the medium peeling means 140, the electric charge between the outer peripheral surface 11 (12) and the print medium M is absorbed. The power can be dissipated.

The medium (M) is transferred from the outer peripheral surface 11 (12) of the drum 10 to a position downstream of the position where the static elimination means (40) is disposed.
Is provided. This medium peeling means 140 is composed of a peeling claw, and can appropriately and temporarily enter the concave portion 13 of the drum 13 to peel off the tip of the medium (M). Peeling nail (14
0) is driven by a motor or a solenoid via a link mechanism or the like.

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 2 shown in FIG.
50, when the device power (power) is turned on (ON),
The main motor 10M is rotated. Since the medium (M) is not charged and held, the charging means 20 (21) is driven to charge the outer surface 11 (12) of the drum 10 with the positive charge Q. When the drum rotation position detector 10S detects that the rotation position (angle) of the drum 10 has reached a preset rotation position, the medium supply unit 90 is driven to set the printing in the supply standby state. Medium M
Is supplied to the drum 10 shown in FIG. 1 at a moving speed equivalent to the drum peripheral speed.

Before or after this (or simultaneously), the contact / separation means 29 is driven to move the electrically insulating roller 30 to the position shown in FIG.
Advance from the dot-dash line state to the solid line state. In other words, the process is executed immediately before the arrival point P is rotationally transferred. The electrically insulating roller 30 is pressed against the drum outer peripheral surface 11 (electrically insulating layer 12) with a constant pressing force by the urging force (tensile force) of the spring 29SP shown in FIG.

Then, the leading end of the print medium M can be immediately attracted and held on the outer peripheral surface 11 (12) of the rotating member (10) by the electric charge attracting force. Further, the leading end (the arrival point P) of the supplied printing medium M is rotated by the rotation of the drum 10 to the electrically insulating roller 30 and the electrically insulating layer 12.
The charging surface Mb of the print medium M can be charged from the point in time when the printing medium M enters.

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 section 250 activates the engagement / separation means 95 to operate the one side of the medium supply means 90. Supply roller 91 is connected to 2
Move to the dotted line state. Therefore, the rear end side of the print medium M is in a free state from both the supply rollers 91 and 92, so that the rotation transfer load of the drum 10 is not generated. Further, since the hardness of the electrically insulating roller 30 is set to 20 ± 5 degrees and pressed against the electrical insulating layer 12, the nip width can be increased.

Thus, the printing medium M is charged by the charging means 20
(21) Drum outer peripheral surface 11 (electric insulating layer 12)
Is charged and held on the drum outer peripheral surface 11 (electric insulating layer 12) by the charge adsorbing force imparted thereto, and is brought into close contact with the electrically insulating roller 30 by pressing contact, and is rotationally transferred in the Y direction with the rotation of the drum 10. . Electrically insulating roller 30
Since the print medium M is driven and rotated and presses against the outer peripheral surface 11 (12) side while the print medium M is moved from the front end side to the rear end side,
The adhesion between the print medium M and the electrical insulating layer 12 can be further improved.

When the drum rotation position detector 10S detects (confirms) that the rear end of the printing medium M has passed the electrically insulating roller 30 during one rotation of the drum 10, the electrically insulating roller 30 FIG.
To the print medium M (the electric insulating layer 12).
Side). That is, in a state where it is not necessary to make contact with the medium (M), the separated state is maintained. 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.

During the subsequent rotation of the drum 4 (2 to 5), ink is jetted from the nozzle head (inkjet nozzle) 200, and printing is performed on the print medium M being rotationally transferred. During this period, the replenishing charging means (22) 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
Is to eliminate the electric charge attracting force between the printed printing medium M and the electrical insulating layer 12 by operating the static elimination means (40), and to mechanically move the leading end side of the printed printing medium M by operating the medium removing means 140. 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.

According to this embodiment, however, the outer surface 11 of the rotating member (10) that rotates at a constant peripheral speed in one direction.
Before the tip of the medium (M) supplied from the outside (90 side) comes into contact with (12), a charging means 20 (21) capable of applying a charge without contacting the rotating member, and a charging means 20 (2)
The outer peripheral surface 11 of the rotating member (10) by the charge adsorbing force according to 1).
(12) a replenishing charging means (22) capable of replenishing the charge-adsorbing force attenuated during rotation to the medium having the charge-adsorbed and held therein, and capable of applying and holding a charge without contacting the rotating rotating member (10). Since the charge adsorption force attenuated during the subsequent rotation is formed so as to be replenishable, the charging efficiency is substantially high, and for example, even if the medium is thick, it can be reliably and stably held.

Further, an electric insulating layer 12 having an electric resistance of 1 × 10 ¹² to 1 × 10 ²⁰ Ω-cm is formed on the outer peripheral surface 11 of the rotating member (10), and the rotating shaft (15) is short-circuited to ground. In addition, since the charging means 20 is formed from the corona discharger 21 that applies the positive charge Q to the electric insulating layer 12, the substantial charging efficiency can be further increased.

Further, after the leading end of the medium (M) supplied from the outside (90 side) comes into contact with the outer peripheral surface 11 of the rotating member (10), it is possible to press the medium against the outer peripheral surface of the rotating member. Since the roller 30 is provided, the medium (M) can be brought into close contact with the outer peripheral surface 11 (12), so that the holding by the charge attraction force can be further strengthened. Since it is possible to mechanically squeeze the rear end side, the entire area of the medium can be uniformly held and wrinkles and the like can be prevented.

Further, since the electrically insulating roller 30 is formed so as to be capable of coming into contact with and separating from the medium (M) held by the rotating member (10), the electrically insulating roller 30 can be applied to the medium (M) and components. Interference can be avoided.

The outer peripheral surface 11 (1) of the rotating member (10)
2) Since the charge removing means (40) for removing the charge adsorbing force for adsorbing and holding the medium (M) is provided, the charge adsorbing force can be removed before the medium (M) is peeled off. The subsequent separation of the medium can be facilitated.

Further, a medium peeling means 140 capable of mechanically peeling the medium from the outer peripheral surface thereof is provided downstream of the position where the static elimination means (40) is disposed in the rotation (Y) direction of the rotating member (10). Therefore, peeling can be performed smoothly and quickly in a series.

Further, the electrically insulating roller 30 is
Since the rotation member is formed so as to be able to follow the rotation of 0, the rotation member (10) does not generate a large rotation load and does not apply unnecessary external force that causes wrinkles to the print medium M. Since it is possible to squeeze to the rear end side, the adhesion to the drum outer peripheral surface 11 (12) can be further enhanced.

Further, since the electrically insulating roller 30 can be pressed against the drum outer peripheral surface 11 (12) by the urging force (tensile force) of the spring 29SP when the contact / separation means 29 is in the forward state, the printing medium is formed. The adhesion of M to the drum outer peripheral surface 11 (12) can be further stabilized and further improved.

Further, since the medium supply means 90 has an attitude 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, the corona discharger 21, the medium supply means 90, the electrically insulating roller 30, the corona discharger 22,
Since the corona discharger 40, the medium peeling means 140, and the nozzle head 200 are arranged in this order in the drum rotation (Y) direction, charging before printing—medium supply—medium pressing—charge replenishment and charge after printing are performed. Removal-medium stripping can be performed quickly and stably in a series.

(Second Embodiment) As shown in FIG. 4, the second embodiment has a basic configuration similar to that of the first embodiment (FIGS. 1 to 3). The charging means 20 (21) and the replenishing charging means (22) in the first embodiment are formed of one common corona discharger 21.

That is, the charging means 20 is formed in a variable charging polarity type. Specifically, the drive control unit 250 increases the charging capability by, for example, increasing the DC output voltage of the power supply unit 21P to a high voltage before holding all the medium (M) by suction, and switches the polarity of the DC output voltage after holding the medium by suction. , Lowering the charging ability at low pressure.

Thus, according to the second embodiment,
In addition to achieving the same operation and effect as in the case of the first embodiment,
Further, the size and cost of the apparatus can be reduced, and the degree of freedom in layout can be increased.

[0072]

According to the first aspect of the present invention, before the tip of the medium supplied from the outside comes into contact with the outer surface of the rotating member rotating at a constant peripheral speed in one direction, the rotating member is contactlessly charged. The rotating means comprises charging means capable of applying, and replenishing charging means capable of replenishing the charge adsorbing force attenuated during rotation to the medium held and held on the outer peripheral surface of the rotating member by the charge adsorbing force of the charging means. Since the rotating member is formed in a non-contact manner, the charge can be applied to the holding surface of the medium and the charge adsorption force attenuated during the rotation after the holding can be supplemented, the substantial charging efficiency is high and the medium is thick, for example. Even if it can be held securely and stably.

According to the second aspect of the present invention, the electric resistance value of the outer peripheral surface of the rotating member is 1 × 10 ¹² to 1 × 10 ²⁰ Ω-c.
m, the rotating shaft is grounded and short-circuited to ground, and the charging means is formed of a corona discharger which applies a positive charge to the electrical insulating layer. And the charging efficiency can be further improved.

According to the third aspect of the present invention, the charging means and the replenishing charging means are formed of a common corona discharger of a variable charging polarity type. In addition to the same effects as described above, the size and cost of the apparatus can be further reduced.

Further, according to the fourth aspect of the present invention, there is provided an electrically insulating roller capable of pressing the medium against the outer peripheral surface of the rotating member after the leading end of the medium supplied from the outside comes into contact with the outer peripheral surface of the rotating member. Since it is provided, the same effects as those of the first to third aspects of the invention can be obtained. Further, since the medium can be brought into close contact with the outer peripheral surface, the holding by the charge attracting force can be further strengthened, and the electric insulation can be achieved. Since the media can be mechanically squeezed from the leading end side to the trailing end side of the medium by the sex roller, the entire area of the medium can be uniformly held and wrinkles and the like can be prevented.

Furthermore, according to the fifth aspect of the present invention, since the electrically insulating roller is formed so as to be capable of coming into contact with and separating from the medium held by the rotating member, the same effect as that of the fourth aspect of the invention can be obtained. In addition, interference of the electrically insulating roller with the medium and components can be avoided.

Furthermore, according to the invention of claim 6, since the outer peripheral surface of the rotating member is provided with the charge removing means for removing the charge attracting force for attracting and holding the medium, the claim 1 is provided.
In addition to the effects similar to those of the inventions according to the fifth to fifth aspects, the medium can be easily separated after holding.

According to the seventh aspect of the present invention, there is provided a medium peeling means capable of mechanically peeling the medium from the outer peripheral surface of the rotating member in the rotation direction downstream of the position where the static elimination means is provided. Therefore, the same effect as that of the invention of claim 6 can be obtained, and further, the peeling can be performed smoothly and quickly in a series.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining a contact / separation unit.

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

FIG. 4 is a schematic side view showing a second embodiment of the present invention.

FIG. 5 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 Electrical insulation layer (outer peripheral surface) 15 Shaft part (rotating shaft) 20 Charging means 21 Corona discharger (charging means) 21P power supply unit 22 Corona discharger (replenishing charging means) 29 contact Separating means 29SP Spring 30 Electrically insulating roller 40 Corona discharger (Electric charge removing means) 90 Medium supply means (external) 140 Medium peeling means 200 Nozzle head (Print head) 207 Inkjet nozzle M Print medium (Medium) Y Rotation direction

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichiro Fujii 570 Ohito, Oni-cho, Takata-gun, Shizuoka Prefecture Inside the Tech Ohi Works, Inc.

Claims (7)

[Claims] A charging means capable of applying a charge to the rotating member in a non-contact manner before a leading end of a medium supplied from the outside comes into contact with an outer peripheral surface of the rotating member rotating at a constant peripheral speed in one direction; A replenishing charging means capable of replenishing the charge attracting force attenuated during rotation to the medium attracted and held on the outer peripheral surface of the rotating member by the charge attracting force of the means. 2. An electric resistance value of 1 on an outer peripheral surface of the rotating member.
An electric insulating layer of × 10 ¹² to 1 × 10 ²⁰ Ω-cm is formed, the rotating shaft is short-circuited to ground, and the charging means is formed of a corona discharger which applies a positive charge to the electric insulating layer. The medium holding device according to claim 1. 3. The medium holding device according to claim 1, wherein said charging means and said replenishment charging means are formed of a common corona discharger having a variable charging polarity. 4. An electric insulating roller is provided which is capable of pressing the medium against the outer peripheral surface side of the rotating member after the tip of a medium supplied from the outside comes into contact with the outer peripheral surface of the rotating member. The medium holding device according to claim 3. 5. The medium holding device according to claim 4, wherein the electrically insulating roller is formed so as to be capable of coming into contact with and separating from the medium held by the rotating member. 6. The medium according to claim 1, further comprising a charge removing means for removing a charge attracting force for attracting and holding the medium on an outer peripheral surface of the rotating member. Holding device. 7. The medium according to claim 6, further comprising a medium separating unit that is capable of mechanically separating a medium from an outer peripheral surface of the rotating member in a rotation direction of the rotating member and downstream of a position where the charge removing unit is disposed. Holding device.