JP2014141030A - Medium conveying device, recording device - Google Patents

Abstract

An apparatus having a configuration for transporting an object to be transported using a transport belt capable of suppressing scattering of ink mist and obtaining a good recording result is provided.
An ink jet printer includes a conveyance belt that adsorbs and conveys a recording sheet by electrostatic adsorption, and a belt charging unit that charges the conveyance belt. The belt charging unit charges the transport belt 9 so that the negative charge amount is larger than the positive charge amount for the entire belt portion constituting the placement surface 9a on which the recording papers P1 and P2 are placed on the transport belt 9. The ink mist positively charged by the Leonard effect is adsorbed by the negatively charged conveying belt 9 as a whole, and the floating of the ink mist inside the apparatus is suppressed.
[Selection] Figure 2

Description

  The present invention relates to a medium conveying apparatus that conveys a medium, and a recording apparatus including the medium conveying apparatus.

  In a recording apparatus typified by a printer, a configuration in which an object to be transported, that is, a recording sheet, is transported using a transport belt may be employed. In order to obtain an appropriate recording quality in such a configuration, it is necessary to prevent the recording paper from lifting from the conveyance belt. As a means for adsorbing the recording paper to the transport belt, an apparatus using electrostatic attraction in addition to air suction has been conventionally used. Patent Documents 1 to 5 disclose such a conventional configuration.

  The printing apparatus described in Patent Document 1 is configured such that, when forming a charging pattern in which charged areas having different polarities alternate on the transport belt, the area excluding the position where the polarity is reversed and the end of the recording paper face each other. ing. That is, in the portion where the charge is switched from “+” to “−”, there are places where the charge becomes zero, but in the vicinity where such charge becomes zero, the “+” charge and the “−” charge are Since they are close to each other, there are regions where the charging is unstable due to the influence of the electric charges. In view of this, the printing apparatus described in Patent Document 1 forms a charging pattern so that the end of the recording paper is not desired in such an unstable region.

In addition, by applying an alternating voltage on the conveyor belt, the positively charged region and the negatively charged region are alternately formed because of the influence of the electric lines of force from the positive charge to the negative charge, the electric force, or the Coulomb force. Is more effective than the electrostatic adsorption force (adsorption force due to dielectric polarization) obtained by uniformly forming a charged region of the same polarity on the conveyor belt. This is because there are cases.
In addition, Patent Documents 3 to 5 disclose a configuration in which a recording medium is electrostatically attracted to a conveyance belt by applying an alternating voltage on the conveyance belt.

JP 2006-264899 A JP 2006-346870 A JP 2008-74558 A JP 2006-103022 A JP 2006-62829 A

  By the way, of the ink ejected from the ink jet recording head, the liquid droplets that do not land on the recording paper (sometimes referred to as ink mist) adhere to the components of the apparatus, or on the recording surface of the recording paper. The technical problem of adhesion has been known for some time.

  Here, the charging characteristics of the ink mist will be described below. When ink droplets are ejected from the recording head, the ink droplets are divided into main droplets that land on the recording paper and satellite droplets that float without landing on the recording paper (this becomes the above-described ink mist). The satellite droplets floating in the air are positively charged by the Leonard effect (the air around the satellite droplets is negatively charged). In addition, the longer the time for which the ink mist drifts in the air, the greater the positive charge amount of the ink mist.

  Therefore, when an alternating voltage is applied to the transport belt to form a charging pattern in which positively charged areas and negatively charged areas are alternately arranged, the positively charged ink mist affects the positively charged areas on the transport belt. As a result, the ink mist may be more significantly scattered.

  In many cases, such a malfunction of the apparatus caused by the scattering of ink mist cannot be dealt with by the end user, and is often repaired by the manufacturer. On the other hand, there is a problem associated with the ink mist adhering to the recording medium, that is, the problem of deterioration in recording quality, but the ink mist generated by one recording floats without adhering to any place. If the amount of ink mist is naturally smaller than the accumulated ink mist, and such ink mist adheres to the entire conveyor belt including the paper area, it will minimize the deterioration in recording quality due to ink mist adhesion. be able to.

  The present invention has been made in view of such a situation, and an object of the present invention is to suppress scattering of ink mist in an apparatus having a configuration for transporting an object to be transported using a transport belt. It is to effectively prevent a problem associated with adhering to the components of the voltage applying voltage.

  In order to solve the above problems, a medium conveying apparatus according to the first aspect of the present invention includes a conveying belt that adsorbs and conveys an object to be conveyed by electrostatic attraction, a belt charging unit that charges the conveying belt, And the belt charging means charges the conveyor belt so that the negative charge amount is larger than the positive charge amount for the entire belt portion constituting the placement surface on which the object to be conveyed is placed on the conveyor belt. It is characterized by.

  According to this aspect, the belt charging means for charging the transport belt is such that the negative charge amount is larger than the positive charge amount for the entire belt portion constituting the mounting surface, that is, the negative charge is dominant. Since the transport belt is charged, the liquid droplets drifting above the placement surface are attracted to the transport belt side and attached. Thereby, scattering of a droplet can be suppressed and the malfunction accompanying a droplet adhering to the component of an apparatus can be prevented.

  According to a second aspect of the present invention, in the first aspect, the belt charging unit includes a charging roller in contact with the transport belt, and a voltage applying unit that applies an alternating voltage to the charging roller, and the voltage application The means applies an alternating voltage to the charging roller so that the area of the negative charging region is larger than the area of the positive charging region.

  According to this aspect, the voltage application means applies the alternating voltage to the charging roller so that the area of the negative charging area is larger than the area of the positive charging area. The entire portion can be charged so that the negative charge amount is larger than the positive charge amount.

  According to a third aspect of the present invention, in the first aspect, the belt charging unit includes a charging roller in contact with the conveyance belt, and a voltage applying unit that applies an alternating voltage to the charging roller, and the voltage application The means applies the alternating voltage to the charging roller so that the maximum value of the negative voltage is larger than the maximum value of the positive voltage.

  According to this aspect, the voltage application means applies the alternating voltage to the charging roller so that the maximum value of the negative voltage is larger than the maximum value of the positive voltage, so that the area of the negative charging area is the area of the positive charging area. The negative charge amount can be increased without increasing it, and the negative charge amount can be increased as a whole without reducing the polarity switching portion of the charging region, that is, while maintaining the electrostatic attraction force.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the belt charging unit minus the area of the placement surface excluding the placement area on which the object to be conveyed is placed. It is characterized by having a structure for charging.

  According to this aspect, the belt charging means for charging the conveyor belt negatively charges the area of the mounting surface on the conveyor belt where the object to be conveyed is placed, excluding the area on which the object to be conveyed is placed. Therefore, the positively charged droplets are attracted and attached to the negatively charged region outside the transported object placement region of the transport belt. Thereby, the adhesion amount of the droplet on the conveyance belt can be increased from the conveyance object, and the adhesion amount of the droplet on the conveyance object can be reduced.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the belt charging unit includes at least the placement area of the transport belt in which a negative charging area and a positive charging area are arranged in a lattice shape. It is characterized in that it is formed in a charged region that is arranged.

  According to this aspect, the belt charging unit forms at least the above-described placement area of the transport belt in a charging area in which a minus charging area and a plus charging area are arranged in a grid pattern. Even if the toner adheres to the transported medium due to the influence of the charged region, it is dispersed as a whole, making it difficult to visually recognize the adhesion of the droplets.

That is, if the negatively charged region and the positively charged region are alternately formed in a band shape, the positively charged droplet adheres to the negatively charged region, so that the droplet adhesion is visually recognized as a band. It becomes easy. However, as described above, the negatively charged region and the positively charged region are formed in a lattice shape, so that the droplets are dispersed as a whole, and even if the droplets adhere to the transported object, it is difficult to visually recognize them. it can.
Then, the positively charged droplets adhere to the entire area of the object to be transported, so that the scattering of the droplets can be effectively suppressed.

  In addition, a large number of switching portions between the positive charging region and the negative charging region are formed on the conveyance belt by the lattice-shaped charging pattern. The electrostatic attraction force (Maxwell stress) applied to the medium due to the influence of the electric force line from the positive charge to the negative charge, the electric force, or the Coulomb force (Maxwell stress) is more effective as the switching area between the positive charge area and the negative charge area increases. Become. Therefore, by forming the grid-like charging pattern, the medium can be more reliably adsorbed on the conveyance belt.

  According to a sixth aspect of the present invention, there is provided a medium conveying apparatus according to any one of the first to fifth aspects, wherein a recording head that performs recording on a medium and the mounting surface described above are disposed so as to face the recording head. And a recording apparatus. According to this aspect, in the recording apparatus, it is possible to obtain the same effect as any of the first to fifth aspects described above.

  According to a seventh aspect of the present invention, in the sixth aspect, a voltage application member to which a positive voltage is applied is provided at a position downstream of the recording head in the medium conveyance path and facing the mounting surface. It is characterized by that.

  The droplets ejected from the recording head tend to scatter to the downstream side in the transport direction due to the action accompanying the movement of the transport belt (the action of the air flow). According to this aspect, since the voltage application member to which a plus voltage is applied is provided at a position downstream of the recording head and facing the mounting surface in the medium conveyance path, the object to be conveyed in the conveyance belt. Of the surface of the mounting surface on which the object to be transported is removed, excluding the mounting region on which the object to be transported is mounted, that is, an electric field is formed between the negatively charged region and the voltage application member, and the droplets scattered thereby Can be effectively adhered to the conveying belt side, and the scattering of droplets can be effectively prevented.

FIG. 3 is a side view of a recording unit in the ink jet printer according to the present invention. FIG. 3 is a plan view schematically showing a first example of a charging pattern on a conveyor belt. The top view which shows typically the 2nd Example of the charging pattern on a conveyance belt. The top view which shows typically the 3rd Example of the charging pattern on a conveyance belt. (A), (B) is a top view which shows the variation of a belt charging means. (A) is a top view which shows the structure of the belt charging means which concerns on 4th Example, (B) is a top view which shows typically the 4th Example of the charging pattern on a conveyance belt. (A) is a top view which shows the structure of the belt charging means which concerns on 5th Example, (B) is a top view which shows typically 5th Example of the charging pattern on a conveyance belt. (A) is a top view which shows the structure of the belt charging means which concerns on 6th Example, (B) is a top view which shows typically 6th Example of the charging pattern on a conveyance belt.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. However, the invention is not limited to the embodiment described below, and various modifications are possible within the scope of the invention described in the claims. Assuming that these are also included in the scope of the present invention, one embodiment of the present invention will be described below.

  FIG. 1 is a side view of a recording unit of an ink jet printer 1 which is an embodiment of a recording apparatus of the present invention, FIG. 2 is a plan view schematically showing a first example of a charged pattern state on a conveyor belt, and FIG. FIG. 4 is a diagram showing the second embodiment, and FIG. 4 is a diagram showing the third embodiment. 5A and 5B are plan views showing variations of the belt charging means.

  6A is a plan view showing the configuration of the belt charging means according to the fourth embodiment, FIG. 6B is a diagram schematically showing the belt charging pattern according to the fourth embodiment, and FIG. ) Is a plan view showing the configuration of the belt charging means according to the fifth embodiment, FIG. 7B is a diagram schematically showing the belt charging pattern according to the fifth embodiment, and FIG. 8A is the sixth embodiment. FIG. 8B is a diagram schematically showing a belt charging pattern according to the sixth embodiment. FIG. In each figure, the components of the ink jet printer 1 are simplified as appropriate.

  In the xyz coordinate system shown in each figure, the x direction and the y direction are horizontal directions, of which the x direction is the paper width direction and the belt width direction (device depth direction), and the y direction is the device direction. These are the left-right direction, the belt moving direction, and the paper transport direction. The z direction is the direction of gravity (the device height direction).

  In FIG. 1, the ink jet printer 1 includes a feed roller 2, and the feed roller 2 supplies a recording paper P as an example of a transported object onto a transport belt 9. On the further upstream side of the feed roller 2, there is provided a feeding means including a detachable paper cassette for storing the recording paper, a feeding roller for feeding the recording paper P from the paper cassette, and the like. In FIG. 1, the feeding means is not shown. Also, the discharge means for discharging the recording sheet P on which recording has been performed is not shown.

  The conveyance belt 9 is an endless belt for adsorbing and conveying the recording paper P on the belt surface, and is entrained between the driving roller 7 and the driven roller 8. The driving roller 7 and the driven roller 8 arranged on the downstream side thereof are arranged in parallel in a substantially horizontal plane at a predetermined interval, whereby the conveying belt 9 is located between the driving roller 7 and the driven roller 8. Both the upper part and the lower part of the belt part located in the position are substantially horizontal. However, the present invention is not limited to this, and when the diameters of the driving roller 7 and the driven roller 8 are different, if the upper part of the transport belt 9 is substantially horizontal, the lower part does not need to be horizontal.

  The drive roller 7 is configured to be rotationally driven by a drive motor (not shown), and this drive motor is driven and controlled by the control unit 11 so that the transport belt 9 is moved in a predetermined direction at a predetermined timing. The motor is driven by a predetermined movement amount at a predetermined movement speed. In addition, the arrow (right arrow and left arrow) in FIG. 1 shows a belt moving direction, and the curved arrow attached to the driving roller 7 and the driven roller 8 shows the rotation direction of both rollers.

As will be described later, the conveyor belt 9 is charged to a predetermined state by the belt charging unit 14, thereby electrostatically adsorbing the recording paper P. For this reason, the conveyor belt 9 is made of an insulating material such as PET, polyimide, fluorine resin, or rubber having at least the surface (outer peripheral surface) having a medium resistance (1 × 10 ¹⁰ Ω / □ or less), and is necessary. Accordingly, carbon black or a conductive filler is mixed to adjust the resistance value, and the amount of retained charge for charging is adjusted.

  The inkjet recording head 3 is disposed above the conveyance belt 9 so as to face the surface of the conveyance belt 9 that is flat. The inkjet recording head 3 is, for example, yellow (Y), magenta (M), cyan (C), or black (K) 4 in order from the moving belt 9 moving direction, that is, the upstream side of the recording paper P conveying direction. It has a nozzle row (not shown) that ejects colored ink droplets (droplets). Then, under the control of the control unit 11, a color image is formed on each recording sheet P conveyed by the conveying belt 9 at a predetermined timing.

  Note that an ink tank (not shown) in which inks of these colors Y, M, C, and K are stored in the apparatus main body (not shown) of the inkjet printer 1 is detachable from or attached to the apparatus main body. Ink is supplied from the ink tank to the inkjet recording head 3 through an ink tube (not shown).

  In the present embodiment, the ink jet recording head 3 is a long head along the width direction (x direction) of the transport belt 9 which is a direction orthogonal to the paper transport direction, that is, the most recording paper expected to be used. This is a non-scanning head formed to a length that can cover the entire width of a large size paper. However, the present invention is not limited to this, and may be a scanning head that discharges ink while moving in the paper width direction (x direction), that is, a so-called serial type recording head.

  In addition, the nozzle plate 3a formed with an ink discharge hole (not shown) that forms a surface facing the conveying belt 9 in the inkjet recording head 3 may be formed of a conductor such as metal, or an insulating material such as silicon. It may be formed of a body or a semiconductor. When the nozzle plate 3a is formed of a conductor such as a metal, when the nozzle plate 3a is grounded, the negative charge of the ink moving in the nozzle plate 3a moves to the nozzle plate 3a side, so that the ink is ejected. Thus, the charged state changes to the positive charging side.

  The lower surface (nozzle formation surface) of the nozzle plate 3a is directed to the upper surface of the transport belt 9, that is, the paper placement surface 9a on which the recording paper P is placed, and the nozzle formation surface is the paper placement surface of the transport belt 9. 9a and a predetermined distance away from each other.

  A second paper detection sensor 5 is provided at a position on the surface of the ink jet recording head 3 that faces the conveyor belt 9 and away from the nozzle plate 3a. The second paper detection sensor 5 is an optical sensor, and includes a light emitting unit and a light receiving unit (not shown), receives light emitted from the light emitting unit at the light receiving unit, and sends a detection signal based on the amount of light to the control unit 11. And send. Thereby, the control unit 11 can detect the passage of the leading edge and the trailing edge of the recording paper P, and can grasp the length of the recording paper P together with the driving speed of the conveying belt 9.

  A first paper detection sensor 4 is provided downstream of the feed roller 2 and upstream of the transport belt 9, that is, between the feed roller 2 and the transport belt 9. The first paper detection sensor 4 is an optical sensor having the same configuration as the second paper detection sensor 5, and the control unit 11 of the inkjet printer 1 receives a detection signal from the first paper detection sensor 4, The timing at which the recording paper P reaches the conveying belt 9, more specifically, the positional relationship between the recording pattern P and a charging pattern (described later) formed on the conveying belt 9 can be controlled. In FIG. 1, the first paper detection sensor 4 is shown in the vicinity of the recording paper P placement area of the transport belt 9. There must be a distance equal to or greater than the distance to one charging roller 16. As a result, it is possible to grasp the area where the leading edge or the trailing edge of the recording paper P is placed on the conveying belt 9, so that the charging of the conveying belt 9 can be controlled.

  Subsequently, a belt charging unit 14 is provided below the driving roller 7 that drives the conveying belt 9. The belt charging unit 14 includes a charging roller 16 and a voltage applying unit 12 that applies a voltage to the charging roller 16.

  The voltage application means 12 is a power supply device configured by an AC power supply, a DC power supply, a known switching regulator, and the like, and is a power supply device that can perform rectification of alternating voltage, polarity inversion, pulse modulation, and the like. The voltage application unit 12 applies a predetermined alternating voltage to the charging roller 16 under the control of the control unit 11. The charging roller 16 is made of, for example, a conductive rubber material.

  On the other hand, a static eliminator 10 is provided below the driven roller 8. The static eliminator 10 is a static eliminator for eliminating the charged state of the conveyor belt 9, and is located upstream of the belt charger 14 in the belt driving direction, and the belt charger 14 is controlled under the control of the controller 11. Before the charging pattern is formed on the conveyor belt 9, the charged state of the conveyor belt 9 is eliminated in advance. The static eliminator 10 can use various types of static eliminator such as a well-known ion-type static eliminator or a self-discharge rectifier represented by a static eliminator brush.

  Reference numeral 19 denotes a voltage application member provided at a position on the downstream side of the ink jet recording head 3 and facing the paper placement surface 9 a of the conveyance belt 9. The voltage application member 19 is made of a conductive material and is applied with a positive voltage.

  Thereby, the following effects are obtained. That is, the ink droplets ejected from the ink jet recording head 3 and floating tend to scatter to the downstream side in the transport direction due to the action accompanying the movement of the transport belt 9 (the action of the air flow). However, an electric field is formed between the negatively charged region portion of the sheet placement surface 9a of the transport belt 9 and the voltage application member 19, thereby effectively adhering scattered ink droplets to the transport belt 9 side. And ink droplets can be effectively prevented from scattering.

  Reference numeral 24 denotes a cleaning roller. The cleaning roller is provided so as to be able to come into contact with the conveyance belt 9, and removes ink droplets, foreign matters, and the like attached to the conveyance belt 9 by being in contact with the conveyance belt 9. The cleaning roller 24 is rotationally driven by a motor (not shown) in a direction that opposes the moving direction of the conveyor belt 9, thereby functioning to wipe the surface of the conveyor belt 9. Note that not only the cleaning roller 24 but also a wiper or the like that can clean the transport belt 9 may be used.

■■■ First Example ■■■
Next, a first embodiment of the charging pattern formed by the belt charging unit 14 will be described with reference to FIG. In FIG. 2, the display formed by enclosing the characters “+” or “−” is an image of the charging polarity (the polarity of the charge generated on the conveying belt) formed on the sheet placing surface 9 a of the conveying belt 9. It expresses. Reference numeral P1 indicates a recording sheet conveyed in advance, and reference numeral P2 indicates a recording sheet conveyed subsequent to the recording sheet P1.

  In the charging pattern shown in FIG. 2, a charging pattern is formed on the transport belt 9 in a state in which a negative charging region and a positive charging region are alternately arranged along the moving direction of the transport belt 9. Here, the length of the negative charging region (the length in the transport direction) is longer than that of the positive charging region. That is, the area of the negative charging region is larger than the area of the positive charging region.

  The symbol Q indicates the length of the negatively charged region, and the positively charged region is formed between the negatively charged regions having the length Q. As described above, since the negatively charged region is formed longer than the positively charged region, the negative charge increases with respect to the charge amount on the paper placement surface 9a of the conveyor belt 9, and the negative charge becomes more dominant. Thus, the positively charged ink droplets drifting above the sheet placement surface 9a are effectively attracted and adhered to the conveying belt 9 side. Thereby, scattering of ink droplets can be effectively suppressed.

■■■ Second Example ■■■
Subsequently, a second embodiment of the charging pattern formed by the belt charging means will be described with reference to FIG. The charge pattern shown in FIG. 3 differs from the first embodiment shown in FIG. 2 in that the length of the minus charge area and the plus charge area in the belt moving direction is the same, that is, the area of the minus charge area and the plus charge area. The area of the area is the same, and the negative charge area is given a higher potential than the positive charge area so that the charge amount of the negative charge area is larger than the charge amount of the positive charge area. In FIG. 3, a “−” display surrounded by a thick circle conceptually indicates that the charge amount is larger (than the plus charge amount).

  In this embodiment, the voltage applying unit 12 applies a voltage to the charging roller 16 so that the maximum value of the negative voltage is larger than the maximum value of the positive voltage when applying the alternating voltage so as to form the charging pattern as described above. . As a result, as in the first embodiment, the negative charge becomes more dominant with respect to the charge amount on the paper placement surface 9a of the transport belt 9, and ink droplets drifting above the paper placement surface 9a are transported. The ink droplets are effectively attracted to the side, and the ink droplets can be effectively prevented from scattering.

■■■ Third Example ■■■
Next, a third embodiment of the charging pattern formed by the belt charging means will be described with reference to FIG.
As shown in the figure, in this embodiment, the belt charging is performed so that the entire area on the sheet placing surface 9a of the conveyor belt 9 is negatively charged except for the sheet placing area on which the recording sheet is placed. The charged state is formed by the means 14. Accordingly, the positively charged ink mist is attracted to and adhered to the negatively charged region outside the paper placement region of the transport belt 9. Thereby, it is possible to suppress the scattering of ink mist in the apparatus and to suppress or prevent various problems associated with the scattering of ink mist. In addition, the amount of ink mist adhering to the transport belt 9 can be increased, the amount of ink mist adhering to the recording surface of the recording paper can be reduced, and a better recording result can be obtained.

  Further, with the charging pattern as described above, the minus charge amount becomes more dominant than the plus charge amount with respect to the belt portion constituting the sheet placement surface 9a in the transport belt 9, that is, the minus charge amount is more than the plus charge amount. Therefore, the ink droplets (positively charged) drifting above the sheet placement surface 9a are effectively attracted to the conveying belt 9 side, and the scattering of the ink droplets can be further effectively suppressed. .

  The charging roller that forms such a charged state is configured, for example, as shown in FIG. In FIG. 5A, the first charging roller 16A has a length L1. The length L1 corresponds to the width of the recording paper P, and an alternating voltage is applied to the first charging roller 16A formed to the length L1 by the voltage applying unit 12A. The length L2 indicates the dimension in the width direction of the conveyor belt 9.

  As a result, in the area where the conveying belt 9 is in contact with the first charging roller 16A (the area where the conveying belt 9 and the recording sheet are in contact), a negative charging area extending in the sheet width direction and a positive charging extending in the sheet width direction are also provided. As shown in FIG. 4, these regions are formed alternately along the paper transport direction. As shown in FIG. 4, a negative voltage is applied to the first charging roller 16A between the sheets (between the preceding sheet P1 and the following sheet P2). Thus, a negatively charged region is continuously formed between the sheets.

On the other hand, the second charging roller 17 is disposed in a region outside the length region of the first charging roller 16A, and is in contact with a region outside the region (paper region) where the first charging roller 16A is in contact with the transport belt 9. A negative voltage is applied to the second charging roller 17 by the voltage applying means 12A. As a result, a negative charging area is continuously formed along the sheet conveyance direction in the area of the conveyance belt 9 that contacts the second charging roller 17.
As a result, a charging pattern as shown in FIG. 4 is formed on the conveyor belt 9.

  In the case of the configuration shown in FIG. 5A, it is assumed that the paper width is fixed. However, as shown in FIG. 5B, the configuration is to cope with a plurality of paper width dimensions. You can also. In FIG. 5B, the charging roller 16B is formed to have a length L0, the charging roller 17B is disposed in a region deviating from the length region of the charging roller 16B, and the charging roller 17A further includes the lengths of the charging rollers 16B and 17B. Arranged in an area outside the area.

  An alternating voltage is applied to the charging roller 16B (however, a negative voltage is continuously applied between sheets). An alternating voltage or a negative voltage is applied to the charging roller 17B according to the paper size. A negative voltage is applied to the charging roller 17A regardless of the paper size.

  For example, when the paper width is L0, an alternating voltage is applied to the charging roller 16B, and a negative voltage is continuously applied to both of the charging rollers 17A and 17B. Accordingly, a charging pattern as shown in FIG. 4 can be formed when the paper width is L0. When the paper width is L1, an alternating voltage is applied to the charging rollers 16B and 17B, and a negative voltage is continuously applied to the charging roller 17A. Accordingly, a charging pattern as shown in FIG. 4 can be formed when the paper width is L1. As described above, according to the configuration shown in FIG. 5B, a charging pattern as shown in FIG. 4 can be formed for two types of paper widths L0 and L1. Incidentally, if a charging roller is further added in addition to the charging rollers 17A and 17B in the above manner, a larger number of paper sizes can be accommodated.

  In this embodiment, the area between the recording paper P2 and the recording paper P1 is formed as a negatively charged area. However, as shown in FIG. 4, the recording papers P1 and P2 facing the negatively charged area between the papers. A charging pattern in the paper placement area is formed so that a positive charging area is arranged at each end of the sheet. That is, the charging pattern is formed such that the leading edge and the trailing edge of the sheet are located between the positive charging area and the negative charging area. As a result, the leading edge and the trailing edge of the paper are positioned at the polarity switching portion of the charging pattern, and an electrostatic adsorption force due to Maxwell stress is effectively obtained, and the lifting of the leading edge and the trailing edge of the paper is effective. Is suppressed.

  In the examples of FIGS. 2 to 4, the negative charging area and the positive charging area are alternately formed to expect the electrostatic adsorption action due to Maxwell stress in the example of FIGS. If a positive charge appears on the recording paper opposite to the negative charge on the belt and attracts them, the charge pattern of the paper placement area is uniformly a negative charge area. good. Alternatively, it may be a charging pattern in which non-charged areas and negatively charged areas are alternately formed. The same applies to other embodiments.

■■■ Fourth Example ■■■
Subsequently, a fourth embodiment of the charging pattern formed by the belt charging means will be described with reference to FIGS. 6 (A) and 6 (B). The fourth embodiment is characterized in that the placement area on which the recording paper P is placed on the transport belt 9 is formed in a charging area in which a minus charging area and a plus charging area are arranged in a grid pattern.

  FIG. 6B schematically shows such a charging pattern, and a region indicated by a symbol Ep (a hatched region) indicates a positively charged region (a region where a positive charge is generated) by a symbol En. Regions (non-hatched regions) indicate negatively charged regions (regions where negative charges are generated), respectively.

  When a charging area extending in the sheet width direction is seen at an arbitrary position in the sheet conveyance direction, the charging area Ck + 1 starts from the minus charging area En, and toward the right in the figure, the plus charging area Ep and the minus charging area En. , ... are alternately located. The next charging area Ck + 2 starts from the positive charging area Ep and is alternately positioned with the negative charging area En, the positive charging area Ep,. In the present embodiment, there is almost no gap between the positively charged region Ep and the negatively charged region En in the paper width direction.

  Further, when the charging area extending in the sheet conveyance direction is viewed at an arbitrary position in the sheet width direction, the charging area Rk + 1 starts from the minus charging area En, and the plus charging area Ep and minus charging are directed upward in the figure. It is located alternately with the regions En,. The next charging region Rk + 2 starts from the positive charging region Ep and is alternately positioned with the negative charging region En, the positive charging region Ep,... Upward in the figure. In the paper transport direction, an uncharged area having a certain width is formed between the positively charged area Ep and the negatively charged area En. This non-charged region is a part where the polarity changes when an alternating voltage is applied, and strictly includes a region where no voltage is applied (non-charged region) and a region where voltage is applied but slightly (weakly charged region). It is.

  As described above, in this embodiment, the belt charging unit forms the placement area on the conveying belt 9 where the recording paper is placed in a charging area in which the minus charging area En and the plus charging area Ep are arranged in a grid pattern. . As a result, even if floating ink droplets adhere to the recording paper due to the influence of the charged region, they are dispersed as a whole, making it difficult to visually recognize the adhesion of the ink droplets.

  In other words, if the negatively charged region and the positively charged region are alternately formed in a band shape, the positively charged ink droplets adhere to the negatively charged region, so that the ink droplet adhesion is visually recognized as a band. It becomes easy. However, since the negatively charged region En and the positively charged region Ep are formed in a lattice shape as described above, ink droplets are dispersed as a whole, and even if floating ink mist adheres to the recording paper, it is difficult to visually recognize it. can do. In addition, since the positively charged ink droplets uniformly adhere to the entire area of the recording paper, scattering of the ink droplets can be effectively suppressed.

  In addition, a large number of switching portions between the positive charging region Ep and the negative charging region En are formed on the conveyor belt 9 by the lattice-shaped charging pattern. The electrostatic force (Maxwell stress) applied to the medium due to the influence of the electric lines of force from the positive charge to the negative charge, the electric force, or the Coulomb force (Maxwell stress) is more effective as the switching area between the positive charging area Ep and negative charging area En increases. It becomes the target. Therefore, by forming the grid-like charging pattern, the recording paper can be more reliably adsorbed onto the conveyance belt 9. In particular, the edge portion of the recording paper P can be adsorbed satisfactorily.

  The belt charging means for forming the lattice-like charging pattern as described above can be configured as shown in FIG. 6A, for example. In FIG. 6A, the belt charging unit includes the first charging unit 25, the second charging unit 28, and the voltage applying unit 12C. In this embodiment, the first charging unit 25 and the second charging unit 28 are used as an alternative to the charging roller 16 (roller for charging the paper region) in FIG. 1, and the region outside the paper region is In FIG. 6A, it is negatively charged by another charging roller (not shown) (for example, the charging roller 17 shown in FIG. 5A) or is set to a non-charged region (non-charged control region).

  The first charging unit 25 has a first charging roller 27 in contact with the conveyor belt 9 on a shaft 26 extending in a belt width direction (x direction) that is a first direction intersecting the moving direction (y direction) of the conveyor belt 9. And arranged at predetermined intervals. The second charging unit 28 includes a second charging roller 30 in contact with the conveyor belt 9, which is positioned on the downstream side (belt moving direction side) of the first charging unit 25, and extends along a shaft 29 extending in parallel with the shaft 26. It is arranged so as to be positioned between one charging roller 27. The first charging roller 27 and the second charging roller 30 are made of, for example, a conductive rubber material.

  The voltage application unit 12 </ b> C applies an alternating voltage to the first charging unit 25 and the second charging unit 28. In FIG. 6A, the symbol Ds indicates the distance between the axes of the first charging unit 25 and the second charging unit 28. In order to form a grid-like charging pattern as shown in FIG. The cycle of the alternating voltage or the distance Ds is set so that an integral multiple of the cycle of the alternating voltage applied by the voltage applying means 12C is equal to the distance Ds.

  In this embodiment, as in the third embodiment, the minus charge amount is larger than the plus charge amount for the entire belt portion constituting the placing surface 9a on which the recording paper is placed on the transport belt 9. A region excluding the placement region on which the recording paper is placed is formed in a negatively charged state. Alternatively, in forming the grid-like charging pattern, a higher voltage may be applied when a minus voltage is applied than when a plus voltage is applied. This is the same in the fifth embodiment described later.

■■■ Fifth Example ■■■
Next, a fifth embodiment of the charging pattern formed by the belt charging means will be described with reference to FIGS. In the fifth embodiment, as shown in FIG. 7B, the loading area on which the recording paper is placed on the conveying belt 9 is formed in a charging area in which a minus charging area and a plus charging area are arranged in a grid pattern. It is characterized by doing. This is the same as the fourth embodiment described above, and this embodiment is different in the configuration of the charging unit that forms the grid-like charging pattern.

  As shown in FIG. 7A, the belt charging unit includes a charging unit 31 and a voltage applying unit 12D. The charging unit 31 includes a charging roller 33 in contact with the conveyor belt 9 along a shaft 32 extending in a belt width direction (x direction) that is a first direction intersecting a moving direction (y direction) of the conveyor belt 9. It is arranged at intervals. The charging roller 33 includes a first region 33a to which a positive potential is applied along the circumferential direction, and a second region 33b that is electrically insulated from the first region 33a and to which a negative potential is applied. It is a complex consisting of The first area 33a and the second area 33b of the charging roller 33 are made of, for example, a conductive rubber material.

  The voltage applying unit 12D includes a direct current power source, and applies a voltage having a reverse polarity to each of the first region 33a and the second region 33b of the charging roller 33. As a result, the negatively charged areas En and the positively charged areas Ep are alternately formed on the transport belt 9 along the belt moving direction by one roller body. The adjacent charging roller 33 is attached to the shaft 32 so that the phases of the first region 33a and the second region 33b are reversed. The positive charging areas Ep are alternately formed, and a grid-like charging pattern is formed as described above.

■■■ Sixth Example ■■■
Next, a sixth embodiment of the charging pattern formed by the belt charging means will be described with reference to FIGS. In the sixth embodiment, as shown in FIG. 8B, the loading area on which the recording paper is placed on the conveyor belt 9 is arranged in a grid pattern with a negatively charged area and an uncharged area (uncharged control area). It forms in the charged area | region which consists of.

  FIG. 8B schematically shows such a charging pattern, where the area indicated by reference numeral En is a negatively charged area (area where negative charges are generated) and the area indicated by reference numeral E0 (negatively charged area). (Region formed between En) indicates a non-charged region (non-charged control region).

  When a charged region extending in the paper width direction is viewed at an arbitrary position in the paper transport direction, the charged region Ck + 1 starts from the negatively charged region En and is directed to the right direction in the drawing in the non-charged region E0 and the negatively charged region En. , ... are alternately located. The next charged region Ck + 2 starts from the non-charged region E0 and is alternately positioned with the negatively charged region En, the non-charged region E0,.

  Further, when the charged region extending in the paper transport direction is seen at an arbitrary position in the paper width direction, the charged region Rk + 1 starts from the negatively charged region En, and the noncharged region E0 and the negatively charged region are directed upward in the figure. It is located alternately with the regions En,. The next charged region Rk + 2 starts from the non-charged region E0 and is positioned alternately with the negatively charged region En, the non-charged region E0,.

  As described above, in this embodiment, the belt charging unit forms the placement area on the conveying belt 9 where the recording paper is placed in a charging area in which the minus charging area En and the non-charging area E0 are arranged in a grid pattern. . As a result, even if the floating ink mist adheres to the recording paper due to the influence of the charged region, it is dispersed as a whole, making it difficult to visually recognize the adhesion of the ink mist.

  In this embodiment, no electric lines of force or electric force or Coulomb force are formed between the negatively charged region En and the non-charged region E0. However, the presence of the negatively charged region En causes static electricity due to dielectric polarization on the recording paper. The electroadsorption force acts, and the recording paper is adsorbed to the conveyance belt 9.

  The belt charging means for forming such a charging pattern includes a charging portion 34 and a voltage applying means 12E as shown in FIG. The charging unit 34 is configured such that a charging roller 36 in contact with the conveying belt 9 is predetermined along an axis 35 extending in a belt width direction (x direction) that is a first direction intersecting a moving direction (y direction) of the conveying belt 9. It is arranged at intervals.

  The charging roller 36 has a semicircular shape in which a half region in the circumferential direction is cut, and is made of, for example, a conductive rubber material. The adjacent charging roller 36 has a phase reversed by 180 °. Further, it is attached to the shaft 35.

  The voltage application unit 12E includes a DC power source, and applies a negative voltage to the charging roller 36. As a result, the negative charging area En and the non-charging area E0 are alternately formed on the transport belt 9 by the single charging roller 36 along the belt moving direction. Also in the belt width direction, the negatively charged areas En and the non-charged areas E0 are alternately formed, and a grid-like charged pattern is formed as described above.

Each of the embodiments described above is an example, and it goes without saying that the present invention is not limited to these embodiments. In particular, in the present embodiment, the present invention is applied to an ink jet printer, but may be applied to other liquid ejecting apparatuses in general.
Here, the liquid ejecting apparatus uses an ink jet recording head, and is not limited to a recording apparatus such as a printer, a copier, and a facsimile machine that discharges ink from the recording head to perform recording on a recording medium. And a device for ejecting a liquid corresponding to the application from a liquid ejecting head corresponding to the ink jet recording head to an ejected medium corresponding to the recording medium, and attaching the liquid to the ejected medium.

  In addition to the recording head, as a liquid ejecting head, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, and an electrode material (conductive paste) used for forming an electrode such as an organic EL display or a surface emitting display (FED) Examples thereof include an ejection head, a bioorganic matter ejection head used for biochip production, and a sample ejection head as a precision pipette.

DESCRIPTION OF SYMBOLS 1 Inkjet printer, 2 Feed roller, 3 Inkjet recording head, 4 1st paper detection sensor, 5 2nd paper detection sensor, 7 Drive roller, 8 Driven roller, 9 Conveyor belt, 10 Static elimination device, 11 Control part, 12, 12A -12E Voltage application means, 14 belt charging means, 16 first charging roller, 17 second charging roller, 19 voltage applied member, 24 cleaning roller, 25 first charging section, 26 shaft, 27 charging roller, 28 second charging Part, 29 axis, 30 charging roller, 31 charging part, 32 axis, 33 charging roller, 33a first area, 33b second area, 34 charging part, 35 axis, 36 charging roller, En negative charging area, Ep plus charging area , E0 Uncharged area, P Recording paper

Claims (7)

A conveyor belt that adsorbs and conveys the object to be conveyed by electrostatic adsorption;
Belt charging means for charging the transport belt,
The belt charging means charges the conveyor belt such that a negative charge amount is larger than a positive charge amount for the entire belt portion constituting a placement surface on which a conveyance object is placed on the conveyance belt;
A medium conveying apparatus characterized by the above. The medium conveying apparatus according to claim 1, wherein the belt charging unit includes a charging roller in contact with the conveying belt;
Voltage application means for applying an alternating voltage to the charging roller,
The voltage application means applies an alternating voltage to the charging roller such that the area of the negative charging region is larger than the area of the positive charging region.
A medium conveying apparatus characterized by the above. The medium conveying apparatus according to claim 1, wherein the belt charging unit includes a charging roller in contact with the conveying belt;
Voltage application means for applying an alternating voltage to the charging roller,
The voltage applying means applies an alternating voltage to the charging roller so that the maximum value of the negative voltage is larger than the maximum value of the positive voltage.
A medium conveying apparatus characterized by the above. 4. The medium conveying apparatus according to claim 1, wherein the belt charging unit is configured to negatively charge a region of the mounting surface excluding a mounting region on which the object to be transported is mounted. 5. Comprising
A medium conveying apparatus characterized by the above. 5. The medium conveyance device according to claim 1, wherein the belt charging unit includes at least the placement area of the conveyance belt in which a negative charging area and a positive charging area are arranged in a grid pattern. Formed in the charged area,
A medium conveying apparatus characterized by the above. A recording head for recording;
The medium conveying device according to any one of claims 1 to 5, wherein the placement surface is disposed so as to face the recording head.
Recording device. The recording apparatus according to claim 6, further comprising a voltage application member to which a positive voltage is applied at a position downstream of the recording head in the medium conveyance path and facing the mounting surface.
A recording apparatus.

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