JP2007118318A - Liquid ejecting apparatus, recording apparatus, and potential control unit - Google Patents

Abstract

Contamination due to charging of a recording paper 170 is prevented.
A recording head 164 having a conductive nozzle plate 166 and ejecting liquid toward the recording paper 170 while reciprocating on the recording paper 170, and the recording paper 170 at a position facing the nozzle plate 166. A platen 150 to be positioned, a counter electrode 310 disposed opposite to the nozzle plate 166 in the direction in which the liquid is ejected, a rib electrode 156 electrically coupled to the recording paper 170, and one end of the counter electrode 310 The other end of the potential difference generating unit 330 is connected to the nozzle plate 166, and when the recording paper 170 exists directly below the nozzle plate 166, the rib electrode 156 is connected to one end of the potential difference generating unit 330 and If there is an area where the recording paper 170 does not exist, the rib electrode 156 is connected to the potential difference generating means 33. And a connection switching means 400 to be connected to the other end.
[Selection] Figure 4

Description

  The present invention relates to a liquid ejecting apparatus. More specifically, the present invention relates to a liquid ejecting apparatus and a recording apparatus for attaching a liquid ejected from an opening of a nozzle plate mounted on a liquid ejecting head to a recording material, and an electric field generating unit that can be used by being mounted on these apparatuses.

  In recent liquid ejecting apparatuses, droplets ejected from the opening of the nozzle plate are miniaturized to about several pl in accordance with a request for improving the resolution of a recorded image. Since such a fine droplet has a very small mass, once ejected, the kinetic energy is rapidly lost due to the viscous resistance of the atmosphere. For example, a droplet of less than 3 pl discharged from the nozzle plate has a velocity of substantially zero when it travels about 3 mm in the atmosphere. Droplets that have lost their kinetic energy are almost balanced by the drop motion due to gravitational acceleration and the viscous resistance of the atmosphere, and it takes a long time to fall completely.

  It is also conceivable to increase the jetting speed of the liquid in order to give a larger kinetic energy to the droplet. However, when the jetting speed from the nozzle plate is actually increased, very fine droplets called ink mist are likely to be generated when the droplets are detached from the nozzle plate. In addition, it has been found that, as the flying speed increases, the viscous resistance of the atmosphere acting on each droplet also increases, so that the reach distance of the droplet is rather shortened.

  Further, in the liquid ejecting apparatus, in the case where the liquid is adhered without leaving a margin at the peripheral portion of the recording material, an inevitable misalignment between the recording material and the liquid ejecting head is expected and the size of the recording material is exceeded. The liquid is jetted over a slightly wide area. For this reason, in the vicinity of both side edges and front and rear end portions of the recording material, the liquid may be discharged even to an area where the recording material does not exist. As for the surplus liquid droplets that do not adhere to the recording material in this manner, the surplus liquid is absorbed by disposing an absorbing member at a position facing the liquid ejecting head in the liquid ejection direction. However, the absorbing member is disposed farther than the recording material with respect to the nozzle plate. Therefore, in order for the liquid droplets to reach the absorbing member, it must fly a distance larger than the recording material. For this reason, many liquids that float without reaching the absorbing member are generated from the liquid ejected to the area where the recording object does not exist.

  The floating droplets generated as a result of various phenomena as described above are called aerosols and float around the moving area of the liquid ejecting head. Part of the aerosol floats to the outside of the liquid ejecting apparatus, adheres to the periphery of the liquid ejecting apparatus, and is contaminated. In addition, most of the aerosol eventually adheres to each part in the liquid ejecting apparatus. In particular, when aerosol adheres to the transport path of a recording material such as a platen, the recording material transported next is contaminated. Further, when the aerosol adheres to the electric circuit, the rotary scale, the linear scale, or various optical sensors of the liquid ejecting apparatus, the apparatus itself may malfunction. Furthermore, when the user touches the aerosol, the user's hand is soiled. Therefore, it has been proposed to prevent the generation of aerosol and actively collect the generated aerosol.

  In the following Patent Document 1, a metal nozzle plate is used as one electrode, and an electric field is formed between an electrode disposed at a position facing the nozzle plate with the object to be processed interposed therebetween and the nozzle plate. Are listed. Since the droplets discharged from the nozzle plate are charged to the same polarity as the nozzle plate for the reasons described later, they receive a Coulomb force acting toward an electrode having a polarity different from that of the nozzle plate in an electric field. Therefore, since it continues to fly to the electrode without being decelerated in the electric field, as a result, droplets floating as an aerosol can be reduced.

In the liquid ejecting apparatus described in Patent Document 2 below, an electric field is formed between the nozzle plate and the object to be processed, and a Coulomb force directed to the object to be processed is applied to the droplet. Thus, it is described that the liquid droplets surely reach the object to be processed and the generation of aerosol is prevented. Further, in the cited document 2, by periodically reversing the polarity of the voltage applied to the object to be processed, fluctuations in the potential of the object to be processed caused by the accumulation of charged liquid in the object to be processed are prevented. Has also been proposed.
JP 2004-202867 A JP 2005-186290 A

  In the liquid ejecting apparatus described in Patent Document 1, since the recording object to be processed is located in the electric field formed between the nozzle plate and the electrode, the recording object is a distance from the nozzle plate or the electrode. Accordingly, the nozzle plate and the electrode are charged at different potentials. For this reason, some of the droplets charged to the same potential as the nozzle plate may be adsorbed by the object to be processed. This means that the object to be processed is contaminated by the electric field formed to reduce the aerosol.

  Further, in the liquid ejecting apparatus described in Patent Document 1, the workpiece is not electrically connected anywhere and is in an electrically floating state. For this reason, when a droplet adheres to and accumulates on the object to be processed by the recording operation, the charge of the droplet is also accumulated on the object to be processed, and the object to be processed is more greatly charged. Accordingly, when the amount of ink discharged in one-pass printing is large, the electric field strength between the nozzle plate and the recording material may exceed the electric field strength between the nozzle plate and the electrode. In such a case, electric lines of force extend from the object to be processed to the nozzle plate and the electrode, and in the next pass, charged droplets discharged from the nozzle plate and passing near the side of the object to be processed are And is contaminated around the edge of the workpiece.

  Furthermore, the structure disclosed in Patent Document 2 prevents the generation of aerosol by causing droplets to adhere to the recording material by Coulomb force. However, when there is no recording paper directly under the nozzle plate, aerosol generation cannot be effectively prevented. Further, once generated, the aerosol is attracted to the side end portion of the recording material existing in the vicinity, and on the contrary, contaminates the vicinity of the peripheral portion of the recording material.

  Thus, it has been found that when an electric field is formed in the vicinity of the nozzle plate for the purpose of reducing floating aerosol, depending on the conditions, the recording material is contaminated.

  In order to solve the above problems, as a first embodiment of the present invention, a conductive nozzle plate is provided, and liquid is ejected from the opening of the nozzle plate toward the recording material while reciprocating on the recording material. A liquid ejecting head, a platen for supporting and positioning the recording material from the back surface at a position facing the nozzle plate in a direction in which the liquid is ejected, and a recording material facing the nozzle plate in the direction in which the liquid is ejected A counter electrode disposed at a distance, a potential control electrode electrically coupled to a recording material supported on the platen, one end connected to the counter electrode, and the other end connected to the nozzle plate A potential difference generating means for generating an electric field between the nozzle plate and the counter electrode; and when a recording object exists directly under the nozzle plate, the potential control electrode is connected to the potential difference generating means. Connected to, if there is a region in which the recording medium is not present directly below the nozzle plate liquid ejection apparatus and a connection switching means for connecting the potential control electrodes at the other end of the potential difference generating means is provided. As a result, when a recording object exists directly under the nozzle plate, an electric field is formed between the nozzle plate and the recording object, so that the liquid discharged from the nozzle plate reliably reaches the recording object. be able to. In addition, when there is no recording material immediately below the nozzle plate, the recording material has the same potential as the nozzle plate, so that droplets charged to the same potential as the nozzle plate do not adhere to the recording material.

  In the liquid ejecting apparatus, the potential control electrode is provided on a platen that supports and positions the recording material from below at a position facing the liquid ejecting head, and is opposite to the surface of the recording material on which the liquid is ejected. The electrode member which contact | abuts the surface of this may be included. Thus, the potential control electrode provided on the platen touches the recording material directly under the nozzle plate to control the potential, so that the potential of the recording material can be controlled efficiently.

  Further, in the above liquid ejecting apparatus, the potential control electrode is rotated together with the conveyance drive roller and the conveyance drive roller which are driven to rotate while contacting the recording material so as to convey the recording material in a direction crossing the reciprocating direction. It may include at least one of a transport driven roller rotated by the transport drive roller while sandwiching the. Thereby, the potential of the recording material can be controlled by using an existing member in the liquid ejecting apparatus. Further, the potential of the recording material is kept the same as that of the nozzle plate before the recording material reaches just below the nozzle plate. Therefore, contamination by aerosol at the front end of the recording material is prevented.

  Further, in the liquid ejecting apparatus, the potential control electrode is rotated together with the discharge driving roller and the discharge driving roller that are driven to rotate while contacting the recording material so as to discharge the recording material in a direction intersecting the reciprocating direction. It may include at least one of a discharge driven roller that is rotated by the discharge drive roller while sandwiching. Thereby, the potential of the recording material can be controlled by using an existing member in the liquid ejecting apparatus. Further, even after the recording material passes just below the nozzle plate, the potential of the recording material is maintained the same as that of the nozzle plate. Therefore, contamination by aerosol at the rear end of the recording material is effectively prevented.

  Further, in the liquid ejecting apparatus, the potential control electrode is rotated together with the conveyance drive roller and the conveyance drive roller which are driven to rotate while contacting the recording material so as to convey the recording material in a direction crossing the reciprocating direction. At least one of a transport driven roller that is rotated by the transport drive roller while sandwiching the recording medium, a discharge drive roller that is rotationally driven while being in contact with the record to eject the record in a direction intersecting the reciprocating direction, and It may include at least one of a discharge driven roller that is rotated by the discharge drive roller while sandwiching the recording material together with the discharge drive roller. Thereby, the potential of the recording material can be controlled by using an existing member in the liquid ejecting apparatus. In addition, both before the leading edge of the recording material reaches directly below the nozzle plate and after the trailing edge of the recording material passes under the nozzle plate, the potential of the recording material is kept the same as that of the nozzle plate. The Therefore, contamination by aerosol at the rear end of the recording material is reliably prevented.

  Furthermore, in the liquid ejecting apparatus, the potential control electrode may include an electrode member having conductivity that contacts the recording material. As a result, good electrical connection can be obtained at a desired position with respect to the recording material, so that it becomes easy to keep the potential of the recording material at the desired potential.

  As a second embodiment of the present invention, a recording head having a conductive nozzle plate and reciprocatingly moving on the recording material and discharging ink from the opening of the nozzle plate toward the recording material; A platen that supports and positions the recording material from the back surface at a position facing the nozzle plate in the ejection direction, and a counter electrode that is disposed farther than the recording material facing the nozzle plate in the ink ejection direction A potential control electrode electrically coupled to the recording material supported on the platen, one end coupled to the counter electrode, the other end to the nozzle plate, and an electric field between the nozzle plate and the counter electrode. And a potential control electrode is connected to one end of the potential difference generating means when there is a recording object directly under the nozzle plate. If there are areas of the recording medium is not present under the recording apparatus and a connection switching means for connecting the potential control electrodes at the other end of the potential difference generating means is provided. Thereby, also in the recording apparatus, the generation of aerosol and the prevention of contamination of the recording material by the aerosol are compatible.

  Furthermore, as a third aspect of the present invention, a liquid ejecting head having a conductive nozzle plate and ejecting liquid from the opening of the nozzle plate toward the recording material while reciprocating on the recording material; An electric field generating unit mounted on a liquid ejecting apparatus having a platen for supporting and positioning a recording material from the back surface at a position facing the nozzle plate in a direction opposite to the nozzle plate, the nozzle in the liquid ejecting direction A counter electrode disposed opposite to the recording material facing the plate, a potential control electrode electrically coupled to the recording material supported on the platen, and one end coupled to the counter electrode The other end of the nozzle plate, a potential difference generating means for generating an electric field between the nozzle plate and the counter electrode, and a potential control when a recording object exists directly under the nozzle plate. An electric field generating unit comprising an electrode connected to one end of the potential difference generating means, and a connection switching means for connecting the potential control electrode to the other end of the potential difference generating means when there is a region where the recording material does not exist immediately below the nozzle plate. Provided. Accordingly, it is possible to add functions for preventing aerosol generation and preventing contamination by aerosol to an existing liquid ejecting apparatus that did not have such a function at first.

  The summary of the invention does not enumerate all necessary features of the present invention. Further, a sub-combination of these feature groups can be an invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a perspective view showing an overview of an ink jet recording apparatus 10 according to one embodiment of the present invention. In this embodiment, an upper case 110 as a cover is opened. As shown in FIG. 1, the ink jet recording apparatus 10 includes a lower case 120 serving as a base of the apparatus, an upper case 110 that forms a casing together with the lower case 120, and a paper support attached to the rear portion of the lower case 120. 130 and a discharge tray 140 formed on the front surface of the lower case 120. Further, the ink jet recording apparatus 10 includes a platen 150 disposed horizontally in the lower case 120 and a carriage 160 disposed above the platen 150 inside the casing. In FIG. 1, the paper support 130 is loaded with a recording sheet 170 as a recording object.

  In the ink jet recording apparatus 10 as described above, the recording paper 170 accommodated in the paper support 130 is taken into the inside one by one by a feeding unit (not shown), and then the platen by a transport unit (not shown). 150 is sent out. Further, the paper is sent to the discharge tray 140 by a discharge unit (not shown). In each of the feeding unit, the conveyance unit, and the discharge unit, the recording paper 170 is fed, conveyed, or discharged by being sandwiched between a driving roller that is rotationally driven and a driven roller that is driven by the driving roller.

  In the ink jet recording apparatus 10, the carriage 160 reciprocates in a direction perpendicular to the conveyance direction of the recording paper 170 above the platen 150. Therefore, the entire upper surface of the recording paper 170 can be scanned by the carriage 160 by alternately conveying the recording paper 170 and reciprocating the carriage 160. Thereby, the carriage 160 can perform a recording operation in an arbitrary area on the upper surface of the recording paper 170.

  FIG. 2 is a perspective view showing the internal mechanism 20 of the ink jet recording apparatus 10 shown in FIG. 1 with the frame 210 including the side portions 212 and 214 extracted. As shown in the figure, the internal mechanism 20 includes a frame 210 disposed substantially vertically rearward, and a pair of side surface portions 212 and 214 that extend forward from both side end portions in parallel to each other. It is mainly formed inside the area to be defined.

  As shown in the figure, in the internal mechanism 20, the carriage 160 is supported by a guide shaft 220 that passes through the carriage 160. The end of the guide shaft 220 is supported by the side portions 212 and 214, and is arranged in parallel to the frame 210 and horizontally. Accordingly, the carriage 160 can move horizontally along the guide shaft 220.

  Behind the carriage 160, a pair of pulleys 232 and 234 and a timing belt 230 hung on the pulleys 232 and 234 are disposed on the front surface of the frame 210. One pulley 234 is rotationally driven by a carriage motor 236. The timing belt 230 is coupled to the rear portion of the carriage 160. Accordingly, the carriage 160 can be reciprocated according to the operation of the carriage motor 236.

  The carriage 160 is loaded with an ink cartridge 162 from above, and includes a recording head 164 on the lower surface thereof. Further, the recording head 164 includes a metal nozzle plate 166 including an opening 168 for ejecting ink on the lower surface thereof. Therefore, ink is ejected downward from the carriage 160. Further, the carriage 160 is coupled to an electronic circuit 250 behind the frame 210 via a tape-shaped multicore cable 240. Since the multi-core cable 240 flexes flexibly as the carriage 160 moves, it does not hinder the reciprocating movement of the carriage 160.

  A platen 150 is disposed below the area where the carriage 160 reciprocates. The platen 150 supports the recording paper 170 passing under the carriage 160 from below, and keeps the distance between the nozzle plate 166 and the recording paper 170 constant. A depression 152 is formed on the upper surface of the platen 150, and the absorbing member 260 is accommodated in the depression 152. The absorbing member 260 receives ink ejected from the recording head 164 toward the area where the recording paper 170 does not exist.

  Note that ink adheres to the absorbing member 260 as the operation time of the ink jet recording apparatus 10 elapses. When the recording paper 170 comes into contact with the absorbing member 260 to which ink has adhered, the back surface of the recording paper 170 is contaminated with ink. Therefore, by forming a rib-shaped portion on the upper surface of the platen 150 and lifting and supporting the recording paper 170 from below, contact between the two is maintained to prevent contact. Specifically, a gap of about 2 to 4 mm is provided between the recording paper 170 and the absorbing member 260. An interval of about 1 mm is also maintained between the surface of the nozzle plate 166 and the surface of the recording paper 170.

  The material of the absorbing member 260 is selected with emphasis on the liquid absorption speed on the surface. For this reason, its own absorption capacity is limited. Therefore, a waste liquid absorbing member 262 having a larger absorption capacity is disposed below the platen 150, and this part and the absorbing member 260 are in contact with each other. The waste liquid absorbing member 262 is made of a material having a large absorption capacity due to capillary action as well as its absorption capacity, and can absorb a large amount of ink from the absorbing member 260.

  On the other hand, a conveyance driving roller 282 and a conveyance driven roller 284 are disposed behind the platen 150 to form a conveyance unit 280. The transport driving roller 282 is rotationally driven by a transport motor 286 disposed behind the frame 210. Further, the conveyance driven roller 284 presses the recording paper 170 against the conveyance driving roller 282. Accordingly, the conveyance driven roller 284 is rotated along with the rotation of the conveyance driving roller 282 and the recording paper 170 is sent out onto the platen 150. Since ink is ejected from the carriage 160 on the platen 150 as described above, an image can be recorded on the recording paper 170 with ink.

  In addition, a discharge driving roller 292 and a discharge driven roller 294 are disposed in front of the platen 150 to form a discharge unit 290. The discharge drive roller 292 is rotationally driven by the power distributed from the transport motor 286 described above. Further, the discharge driven roller 294 presses the recording paper 170 that has passed through the platen 150 against the discharge driving roller 292. Accordingly, as the discharge driving roller 292 rotates, the discharge driven roller 294 is rotated and the recording paper 170 is sent out from the platen 150 to the outside.

  Further, in the internal mechanism 20, a cap member 270 is disposed on the side of the platen 150 on the side surface 212 side. The cap member 270 can move up and down, and rises when the carriage 160 stops at the home position close to the side surface portion 212 to seal the lower surface of the nozzle plate 166. Further, the inside of the cap member 270 is coupled to the pump unit 272. The pump unit 272 can suck ink adhering to the surface of the nozzle plate 166. The ink sucked by the pump unit 272 is absorbed by the waste liquid absorbing member 262 through a pipe (not shown).

  Further, wiping means 274 is disposed between the platen 150 and the cap member 270. When the carriage 160 released from the sealing by the cap member 270 passes above, the wiping means 274 wipes and cleans the lower surface of the nozzle plate 166.

  FIG. 3 is a cross-sectional view schematically showing the structure of the electric field generating mechanism 31 formed in the ink jet recording apparatus 10 as described above. The electric field generating mechanism 31 includes a potential difference generating unit 330. The potential difference generating means 330 has a pair of outputs of a positive electrode and a negative electrode, and an electric field can be formed between members connected to the outputs.

In this embodiment, the negative electrode of the potential difference generating unit 330 is connected to the nozzle plate 166. Further, the absorbing member 260 is accommodated in the depressed portion 152 of the platen 150, and the counter electrode 310 is further inserted between the lower surface of the absorbing member 260 and the bottom surface of the depressed portion 152. The counter electrode 310 is connected to the positive electrode of the potential difference generating means 330 through a short circuit protection resistor 320. Therefore, when the potential difference generating unit 330 operates, an electric field E ₁ corresponding to the potential difference generated by the potential difference generating unit 330 is formed between the nozzle plate 166 and the counter electrode 310.

  The pair of outputs of the potential difference generating unit 330 is connected to the input side of the switching unit 400. The switching unit 400 connects one of the input voltages to the output side under the control of a signal to be recorded outside to be described later.

On the other hand, the platen 150 further includes a rib portion 154 protruding upward, and the recording paper 170 is positioned in the vertical direction by being supported by the upper end thereof. A rib electrode 156 made of a conductive material is attached to the upper end of the rib portion 154. The rib electrode 156 is in contact with the lower surface of the recording paper 170 and is connected to the output side of the switching unit 400. Therefore, on the platen 150, the recording paper 170 is connected to the positive electrode or the negative electrode of the potential difference generating unit 330 according to the connection state of the switching unit 400. In each state, the potential of the recording paper 170 is the same as either the counter electrode 310 or the nozzle plate 166. Accordingly, in a state in which the potential of the recording paper 170 is the same as that when the counter electrode 310, as described later, the electric field E ₂ is formed between the nozzle plate 166 and the recording paper 170.

  As described above, the rib electrode 156 functions as a potential control electrode that determines the potential of the recording paper 170. As already described, the platen 150 and its rib portion 154 are members formed of an insulating resin. Therefore, the counter electrode 310 and the rib electrode 156 are not short-circuited with each other.

  In the electric field generating mechanism 31, the counter electrode 310 is plated with a metal that is corrosion resistant to the ink of the ink jet recording apparatus 10, for example, a wire, a plate or a foil of gold, stainless steel, or nickel, or these metals. It can be formed of a wire member, a plate member, a foil member, or a net-like or lattice-like member combining these materials. As another aspect, the counter electrode 310 can be formed of a conductive coating layer, a plating layer, a thick film layer, a thin film layer, or the like formed directly on the depressed portion 152 of the platen 150.

  Further, since the rib electrode 156 slides with respect to the recording paper 170, high wear resistance is required in addition to conductivity. Specifically, stainless steel, nickel-plated iron, iron containing duralumin, chromium or molybdenum, tungsten, titanium, an alloy containing titanium, and the like can be preferably exemplified, but are not limited thereto. Moreover, it can also form integrally with the platen 150 by embedding, sticking, or two-body molding using materials, such as carbon, a metal, and a conductive polymer. Further, an amorphous semiconductor such as selenium or silicon or a metal can be formed by partial vapor deposition on the rib portion 154.

Furthermore, the absorbing member 260 is preferably formed of a conductive material having a surface resistivity of less than 10 ⁸ Ω / □. Specifically, a conductive material such as polyethylene or polyurethane mixed with a conductive material such as metal or carbon is foamed, and a conductive material such as metal or carbon is adhered to a resin foam such as polyethylene or polyurethane. A plated or plated one can be used. In addition, a resin foam material such as polyethylene or polyurethane impregnated with an electrolyte solution can be used as the absorbing member 260.

  The absorbing member 260 directly receives ink that has been ejected from the nozzle plate 166 and has not adhered to the recording paper 170. At this time, if the absorption speed of the absorbing member 260 is slow, the ink generates a so-called milk crown by an impact that collides with the surface of the absorbing member 260. Since fine ink droplets are generated from the periphery of the milk crown, which also causes aerosol generation, it is advantageous that the absorbing member 260 has a high absorption rate, in other words, a high porosity.

  Although not shown, the absorbing member 260 partially communicates with the waste liquid absorbing member 262 disposed below the platen 150 in FIG. For this reason, since the ink absorbed by the absorbing member 260 is sequentially absorbed by the waste liquid absorbing member 262 having higher absorbing power, the absorbing power of the absorbing member 260 is maintained for a long period of time.

  FIG. 4 is a schematic diagram for explaining the operation of the electric field generating mechanism 31, and shows a state in which the output of the switching unit 400 is connected to the positive electrode of the potential difference generating unit 330. The nozzle plate 166 has a plurality of openings 168 for ejecting ink. Further, as indicated by an arrow X in the drawing, the nozzle plate 166 moves from right to left in the drawing as the carriage 160 moves.

  Here, the ink pushed out from the opening 168 of the nozzle plate 166 becomes an ink column 340 that hangs down from the nozzle plate 166 at the moment immediately before the ink droplet 342 is formed. At this time, electric charges are accumulated between the tip A of the ink column 340 and the region B near the ink column 340 on the lower surface of the nozzle plate 166 by a so-called lightning rod effect.

  That is, the lightning rod effect referred to here is a region B on the surface of the nozzle plate 166 surrounded by a cone having an apex angle of 50 ° to 60 ° with the tip A (lower end in the figure) of the ink column 340 as an apex. It contributes to the charging of 342. Due to the lightning rod effect, the ink droplet 342 has a charge q that is larger than the charge corresponding to the horizontal cross-sectional area of the ink column 340 and has the same polarity as the nozzle plate 166.

On the other hand, as shown in the figure, when the recording paper 170 exists immediately below the nozzle plate 166, the output of the switching means 400 is connected to the positive electrode of the potential difference generating means 330. Accordingly, the recording paper 170 is connected to the positive electrode with respect to the nozzle plate 166 connected to the negative electrode, and an electric field E ₂ is formed between the nozzle plate 166 and the recording paper 170.

Therefore, the droplet charged with the charge q in the same polarity as the nozzle plate 166 obtains kinetic energy from the electric field E ₂ by the Coulomb force F (qE), moves downward without being decelerated, and reliably reaches the recording paper 170. To reach. As a result, the generation of aerosol that floats without reaching the recording paper 170 is prevented.

  FIG. 5 is a diagram illustrating the operation of the electric field generating mechanism 31 when a region where the recording paper 170 does not exist is generated immediately below the nozzle plate 166 at both side portions or front and rear end portions of the recording paper 170. The same constituent elements as those in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

As shown in the figure, when the recording paper 170 does not exist immediately below the nozzle plate 166, the switching unit 400 connects the output to the negative electrode of the potential difference generating unit 330. Accordingly, the recording paper 170 has the same potential as the negative electrode of the potential difference generating unit 330, that is, the same potential as the nozzle plate 166. Therefore, an electric field E ₁ is formed between the nozzle plate 166 and the absorbing member 260 and the counter electrode 310 immediately below the nozzle plate 166.

  As described above, the ink droplets ejected from the nozzle plate 166 are charged with the charge q to the same polarity as the nozzle plate 166. Therefore, the kinetic energy due to the Coulomb force F (qE) is obtained from the electric field E, moves downward without being decelerated, and finally reaches the absorbing member 260.

  In this state, the nozzle plate 166 and the recording paper 170 are at the same potential, and the ink droplets 342 charged to the same polarity as the nozzle plate 166 are not attracted to the recording paper 170. Therefore, the ink droplet 342 directed toward the absorbing member 260 does not adhere to the side end surface of the recording paper 170 and become contaminated.

  In the above embodiment, the counter electrode 310 is connected to the positive side of the potential difference generating unit 330, and the nozzle plate 166 and the recording paper 170 are connected to the negative side of the potential difference generating unit 330. However, the same function can be realized even if all the polarities are reversed and connected. Further, by setting one potential of the potential difference generated by the potential difference generating means 330 to the ground potential, the wiring in the electric field generating mechanism 31 can be simplified.

In order to prevent aerosolization by applying a Coulomb force to ink droplets in the ink jet recording apparatus 10 as shown in FIGS. 1 to 5, the electric field intensity of the electric field E ₁ or E ₂ is about 100 kV / m. Is desirable. In addition, when a potential difference is formed using the nozzle plate as one electrode to form such an electric field, the charge accumulated in the droplets ejected from the nozzle plate 166 is about 4 × 10 ⁻¹⁴ Q.

On the other hand, when the recording paper 170 is ordinary fine paper or coated with porous silica or the like, its volume resistivity is about 10 ⁷ to 10 ¹³ Ωcm. When conductive ink permeates such a recording paper 170, its volume resistivity decreases to 10 ⁵ to 10 ⁷ Ωcm. Further, the surface resistivity of the recording paper 170 to which the ink is attached is about 10 ³ to 10 ⁷ Ω / □.

  Therefore, when the potential control electrode (rib electrode 156 in FIG. 4) formed of a metal having sufficiently high conductivity is brought into contact with the recording paper 170 and connected to the potential difference generating means 330, the recording paper 170 itself and the recording paper are used. Through the ink on 170, the potential of the recording paper 170 can be controlled so as to match the output voltage of the potential difference generating means 330. Further, even when charged ink droplets are deposited on the recording paper 170, the charge of the ink droplets is discharged through the recording paper 170 itself, the ink droplets 344 attached thereto, and the rib electrode 156, so that the potential of the recording paper 170 is reduced. Will not fluctuate.

  FIG. 6 is a cross-sectional view schematically showing the structure of the electric field generating mechanism 32 according to another embodiment. In FIG. 6, the same components as those in the other drawings are denoted by the same reference numerals, and redundant description is omitted.

  As shown in the figure, the structure of the electric field generating mechanism 32 according to this embodiment has a characteristic characteristic of the shape of the rib electrode 156. That is, the rib electrode 156 penetrates the rib portion 154 of the platen 150 up and down, and the lower end of the rib electrode 156 is exposed on the lower surface of the platen 150. Therefore, the wiring between the rib electrode 156 and the potential difference generating means 330 can be coupled at the lower part of the platen 150. According to such a structure, the functions as the rib electrode 156 and the electric field generating mechanism 32 are the same as those of the electric field generating mechanism 31 shown in FIG. high.

  FIG. 7 is a cross-sectional view schematically showing the structure of an electric field generating mechanism 33 according to another embodiment. Also in FIG. 7, the same reference numerals are given to the same constituent elements as those in the other drawings, and redundant description is omitted.

  As shown in the figure, in order to eject ink from the recording head 164 and attach it to the recording paper 170, the recording paper 170 must be fed onto the platen 150. Further, the recording paper 170 on which ink is adhered on the platen 150 must be sent out from the platen 150 to the outside. Such conveyance and discharge of the recording paper 170 are performed by a conveyance unit 280 and a discharge unit 290 each including a pair of rollers.

  The conveyance unit 280 includes a conveyance driving roller 282 that contacts the lower surface of the recording paper 170 and a conveyance driven roller 284 that contacts the upper surface of the recording paper 170 and presses the conveyance driving roller 282. Here, the transport driving roller 282 is rotationally driven by the transport motor 286. On the other hand, the conveyance driven roller 284 does not have a driving force itself, and is rotated by the rotation of the conveyance driving roller 282 while pressing the recording paper 170 against the conveyance driving roller 282. The transport driving roller 282 and the transport driven roller 284 continue to touch the recording paper 170 until the rear end passes after the front end of the recording paper 170 reaches. Therefore, the potential of the recording paper 170 can be controlled via the transport unit 280 by forming the transport drive roller 282 from a conductive material and simultaneously connecting it to the potential difference generating means 330.

  In addition, the discharge unit 290 includes a discharge drive roller 292 that contacts the lower surface of the recording paper 170 and a discharge driven roller 294 that contacts the upper surface of the recording paper 170 and presses against the discharge drive roller 292. Here, the discharge drive roller 292 is rotationally driven by the transport motor 286 via a transmission mechanism (not shown). On the other hand, the discharge driven roller 294 itself has no driving force, and is rotated by the rotation of the discharge drive roller 292 while pressing the recording paper 170 against the discharge drive roller 292. The discharge driving roller 292 and the discharge driven roller 294 continue to touch the recording paper 170 until the rear end passes after the front end of the recording paper 170 arrives. Therefore, the potential of the recording paper 170 can be controlled via the discharge unit 290 by forming the discharge drive roller 292 from a conductive material and connecting it to the potential difference generating unit 330.

  Further, both the discharge driving roller 292 and the discharge driven roller 294 are formed of a conductive material, and both are electrically connected to the potential difference generating unit 330, so that the leading edge of the recording paper 170 approaches the platen 150. Thus, the potential of the recording paper 170 can be continuously controlled until the trailing edge passes over the platen 150. Therefore, the aerosol that is discharged from the nozzle plate 166 and floats above the platen 150 flies toward the counter electrode 310 and is absorbed by the absorbing member 260 without being adsorbed by the recording paper 170.

  Examples of the material of the transport driving roller 282 and the discharge driving roller 292 include metal materials having rigidity and conductivity such as iron, nickel-plated iron, and stainless steel. Further, in the case of the conveyance drive roller 282, it is also preferable to improve the frictional force of the surface by attaching alumina particles or the like to the surface for the purpose of preventing the recording paper 170 from sliding. Further, instead of attaching alumina particles, the surface may be covered with conductive rubber or the like.

  FIG. 8 is a cross-sectional view schematically showing the structure of an electric field generating mechanism 34 according to another embodiment. Also in FIG. 8, the same reference numerals are given to the same constituent elements as those in the other drawings, and redundant description is omitted.

  As shown in the figure, in this embodiment, the conveyance driven roller 284 and the discharge driven roller 294 are electrically connected to the potential difference generating unit 330 in each of the conveyance unit 280 and the discharge unit 290. The function thus obtained is the same as that shown in FIG. 7, but this embodiment has the following advantages. That is, the transport drive roller 282 and the discharge drive roller 292 are both mechanically coupled to a rotation transmission mechanism such as a gear group for rotationally driving. Therefore, the mechanical contact in these transmission mechanisms can be used to electrically connect to the potential difference generating means 330. To that end, if the rotation transmission mechanism is entirely formed of a conductive material value. Don't be. However, this type of rotation transmission mechanism is often formed by a gear formed of a resin material, and replacing this with a metal material leads to an increase in manufacturing cost, an increase in operating noise, and the like.

  In this respect, since the conveyance driven roller 284 and the discharge driven roller 294 are only supported so as to be rotatable, they are formed of a conductive material and the shaft support means is electrically connected to the potential difference generation means 330. Can easily form the potential difference control means. In addition, as a material of the conveyance driven roller 284 and the discharge driven roller 294, a conductive metal such as iron, nickel-plated iron, and stainless steel, or a conductive resin material including carbon or metal powder is used. Can do.

  FIG. 9 is a cross-sectional view schematically showing the structure of an electric field generating mechanism 35 according to still another embodiment. Also in FIG. 9, the same reference numerals are assigned to the same components as those in the other drawings, and duplicate descriptions are omitted.

  As shown in the drawing, in this embodiment, in each of the transport unit 280 and the discharge unit 290, all of the transport drive roller 282, the transport driven roller 284, the discharge drive roller 292, and the discharge driven roller 294 are potential difference generating means. 330 is electrically connected. The functions thus obtained are the same as those shown in FIGS. 7 and 8, but this embodiment has the following advantages. That is, each roller is in contact with the recording paper 170, but when the recording paper 170 is actually conveyed or discharged, the contact and separation are repeated microscopically. For this reason, when focusing on a single roller, the electrical connection when the recording paper 170 is not stable. However, by increasing the number of rollers in contact with the recording paper 170, since any roller is in contact with the recording paper 170 as a whole, the potential of the recording paper 170 can be stabilized.

  FIG. 10 is a cross-sectional view schematically showing the structure of an electric field generating mechanism 36 according to another embodiment. Also in FIG. 10, the same reference numerals are given to the same constituent elements as those in the other drawings, and redundant description will be omitted.

  In the embodiment shown in the figure, a plurality of conductive brushes 350 are mounted as means for obtaining electrical connection to the recording paper 170. The conductive brush 350 is formed of a member having both conductivity and elasticity, and one end thereof is electrically connected to the potential difference generating unit 330. The other end of the conductive brush 350 is in contact with the recording paper 170 at a plurality of locations. That is, in the conveyance direction of the recording paper 170, immediately before the platen 150, the conductive brush 350 is disposed on the front surface and the back surface of the recording paper 170, and is in contact with the front surface and the back surface of the recording paper 170, respectively. Further, immediately after the platen 150, a conductive brush 350 is disposed on the back side of the recording paper 170 and is in contact with the back side of the recording paper 170.

  In such an embodiment, a dedicated member called the conductive brush 350 must be introduced. However, since the conductive brush 350 is a dedicated part for obtaining an electrical connection, the arrangement can be freely selected. Therefore, the platen 150 and the nozzle plate 166 that are involved in aerosol collection can be disposed in the immediate vicinity, and the potential of the recording paper 170 can be controlled efficiently. In addition, the conductive brush 350 is listened to by a resin wire containing carbon or metal powder in addition to a metal wire such as stainless steel.

  FIG. 11 is a block diagram showing an example of the structure of the electronic circuit 41 that generates an external signal to be recorded for controlling the operation of the switching unit 400 in each of the above embodiments. As shown in the figure, the electronic circuit 41 receives an initialization signal Sr, a moving distance pulse Ppf, a recording object presence / absence signal Spe, and a side edge signal Sw, and outputs an outside recording signal. The initialization signal Sr is a signal that is input from the initialization input 440 at the start of the operation of the electronic circuit 41 and initializes all the values of each element.

  Here, the movement distance pulse Ppf is a pulse signal supplied from the movement distance detection means 412. The moving distance detection unit 412 is a transmission type sensor or a reflection type sensor that measures the scale of the rotary encoder 410 that rotates together with the conveyance driving roller 282, and outputs a pulse for every fixed conveyance amount of the recording paper 170.

  The recorded object presence / absence signal Spe is a binary signal that is supplied from the recorded object detection means 420 and notifies the presence / absence of the recording sheet 170. In this embodiment, the signal is present if the recording sheet 170 exists. Is set to “HI”, and if the recording paper 170 does not exist, the value is set to “LOW”. The recorded object detection means 420 is formed by a transmissive sensor, a reflective sensor, a contact microswitch, or the like disposed on the conveyance path of the recording paper 170.

  The side end signal Sw is a binary signal supplied from the recording object width detection unit 430. The recorded object width detection means 430 is a reflective sensor that is transported to the carriage 160 together with the nozzle plate 166, and is disposed along the movement direction of the carriage 160 with respect to the nozzle plate 166. Further, when the carriage 160 itself reaches the side end portion of the recording paper 170 as the carriage 160 reciprocates, the output value is changed to notify the fact. In this embodiment, the value of the side edge signal Sw is “HI” if the recording paper 170 is present, and the value of the side edge signal Sw is “LOW” if the recording paper 170 is not present.

  The movement distance pulse Ppf output from the movement distance detector 412 is input to the pulse inputs of the transport subtraction counter 450 and the discharge subtraction counter 460. The transport subtraction counter 450 sets a counter initial value when the PRESET_a input signal rises, and sets the value of the counter output signal Sdc_a to LOW. Here, the counter initial value is a value obtained by converting the physical distance between the recording object detection means 420 and the feed side end of the row of openings 168 into the number of pulses of the movement distance pulse Spe. When the START_a input becomes HI, the carrier subtraction counter 450 subtracts the counter value from the initial counter value by the number of pulses input from the pulse input Pin_a, and when the subtraction value becomes 0, the value of the carrier subtraction counter output signal Sdc_a is obtained. HI is used to stop the operation.

  Further, when the PRESET_b input signal rises, the discharge subtraction counter 460 sets the counter initial value and sets the value of the counter output signal Sdc_b to LOW. Here, the counter initial value is a value obtained by converting the physical distance between the recording object detection means 420 and the discharge side end of the row of the openings 168 into the number of pulses of the movement distance pulse Spe. When the START_b input becomes HI, the discharge subtraction counter 460 subtracts the counter value from the initial counter value by the number of pulses input to the pulse input Pin_b. When the subtraction value becomes 0, the discharge subtraction counter 460 calculates the value of the carrier subtraction counter output signal Sdc_b. HI is used to stop the operation.

  Here, the PRESET_a input of the transport subtraction counter 450 receives the output of the logical sum gate 452, and the logical sum of the initialization signal Sr, the recording object presence / absence signal Spe, and the counter output signal Sdc_b of the discharge subtraction counter 460 is input. The The PRESET_b input of the discharge subtraction counter 460 receives the output of the logical sum gate 462, and the logical sum of the initialization signal Sr and the counter output signal Sdc_a of the transport subtraction counter 450 is input.

  Further, the recording presence / absence signal Spe is input to the START_a input of the transport subtraction counter 450 via the pulse generator 426, and the recording target signal Spe is input to the START_b input of the discharge subtraction counter 460 via the inverter 422 and the pulse generator 424. An object presence / absence signal Spe is input. Note that both of the pulse generators 424 and 426 change the value of the output signal OUT to HI at the rising edge of the input signal IN, with the value becoming LOW at the rising edge of the initialization signal Sr.

  The counter output signal Sdc_a of the transport subtraction counter 450 as described above and the side end signal Sw output from the recording material width detection unit 430 are input to the AND gate 470, and the logical product of both is used as an outside signal to be recorded. Output to the outside.

FIG. 12 is a timing chart 42 showing the operation of the electronic circuit 41 shown in FIG. As shown in the figure, with the start of operation of the ink jet recording apparatus 10, the initialization signal Sr rises at a timing _{T 11,} conveyed down counter 450 and discharged down counter 460 is initialized, the count output Sdc_a, the Sdc_b The output value is LOW. The pulse generators 424 and 426 are also initialized.

Then, the recording sheet 170 when it is loaded, the movement distance pulses Ppf is generated at a timing _{T 12.} However, the period T _{12 to} T ₁₃ from when the recording paper 170 is loaded until the printing start position is reached, and the period T _{14 to} T ₁₅ after the recording operation is finished and discharged are the movement distance pulse Ppf. Are output continuously. Moreover, the period _T 13 _{through T 14} in which the recording operation is performed, since the reciprocating movement of the conveyor and the carriage 160 of the recording sheet 170 is executed alternately, the period in which the carriage 160 is reciprocally moved, the moving distance pulse Ppf Does not occur.

Subsequently, when the front end of the recording sheet 170 to the timing _{T 16} passes through the recording medium detecting unit 420, the value of the recording material presence or absence signal Spe is HI. Therefore, the output of the pulse generator 426 becomes HI, and the START_a input of the carrier subtraction counter 450 becomes HI. The carrier subtraction counter 450 sets the counter output Sdc_a to LOW at the rising edge of the PRESET_a input and the START_a input, and starts subtraction for each pulse input to the pulse input Pin_a input. At this time, the value of the signal outside the recording object is LOW.

Further, when the count value of the transfer down counter 450 becomes 0 is subtracted, at timing T _17, counter output Sdc_a transitions to HI, the output value of the AND gate 470 is a material to be recorded outside the signal side edge signal It becomes the same value as Sw. When the PRESET_b signal that receives the logical sum of the count output Sdc_a of the transport subtraction counter 450 and the initialization signal Sr rises, the counter output Sdc_b of the discharge subtraction counter 460 transitions to LOW.

Further, at timing _{T 18,} the trailing edge of the recording sheet 170 passes through the material to be recorded detecting means 420, the recording material presence or absence signal Spe transitions to LOW. Since the discharge subtraction counter 460 receives the recording object presence / absence signal Spe via the inverter 422 and the pulse generator 424, the START_b input transitions to HI. Therefore, the discharge subtraction counter 460 starts subtraction for each pulse input to the pulse input Pin_b. When the count value becomes 0, at the timing _{T 19,} it shifts the count output Sdc_b to HI. For this reason, the count output Sdc_a of the transport subtraction counter 450 transitions to LOW, so that the output of the AND gate 470 becomes LOW regardless of the state of the side end signal Sw output by the recording material width detection means 430.

  As described above, the signal outside the recording object output from the electronic circuit 41 changes depending on whether or not the recording sheet 170 exists directly below the nozzle plate 166 in both the transport direction and the width direction of the recording sheet 170. To do. Therefore, the connection of the rib electrode 156 can be appropriately switched to the positive electrode side or the negative electrode side of the potential difference generating unit 330 by controlling the switching unit 400 based on the value of the signal outside the recording object.

  FIG. 13 is a block diagram showing another structure of the electronic circuit 43 that generates an external signal to be recorded for controlling the operation of the switching unit 400. In the figure, the same components as those in the other figures are denoted by the same reference numerals and redundant description is omitted. The electronic circuit 43 also receives the initialization signal Sr, the movement distance pulse Ppf, the recorded object presence / absence signal Spe, and the side end signal Sw, and outputs the signal outside the recorded object.

  The electronic circuit 43 includes a subtraction counter 490 that receives the movement distance pulse Ppf, and a pair of storage means that holds the count initial value of the subtraction counter 490, that is, a carrier pulse number storage means 482 and a discharge pulse number storage means 484. Yes. Here, the count initial value Data1 of the conveyance pulse number storage means 482 is converted from the physical distance between the recording object detection means 420 and the feed side end of the row of openings 168 into the number of pulses of the movement distance pulse Spe. The count initial value Data2 of the ejection pulse number storage means 484 is the physical distance between the recording object detection means 420 and the ejection side end of the row of the openings 168, and is set to the number of movement distance pulses Spe. It is a converted value.

  The carrier pulse number storage means 482 receives the recorded object presence / absence signal Spe as the enable signal ENB. Accordingly, when the value of the recorded object presence / absence signal Spe is HI, the count initial value is output to the subtraction counter 490 as Data1. Further, when the value of the recording object presence / absence signal Spe is LOW, the output is set to a high impedance state.

  Further, the ejection pulse number storage means 484 receives the recording object presence / absence signal Spe as the enable signal ENB via the inverter 422. Therefore, when the value of the recording object presence / absence signal Spe is LOW, the count initial value is output to the subtraction counter 490 as Data2. When the value of the recorded object presence / absence signal Spe is HI, the output is set to a high impedance state.

  On the other hand, the subtraction counter 490 receives the moving distance pulse Ppf at the pulse input Pin, and receives the recording object presence / absence signal Spe via the pulse generator 492 at the START input. The initialization signal Sr is received at the RESET input, and is initialized when the initialization signal Sr transits to HI, and at the same time, the value of the counter output Sdc is set to HI.

  When the START input rises to HI, the subtraction counter 490 reads Data1 or Data2 from the carrier pulse number storage unit 482 or the discharge pulse number storage unit 484 to the Data input, sets it to the initial count value, and sets the movement distance pulse Ppf. Subtract the number of pulses. Further, the value of the count output Sdc is set to LOW. When the count value becomes 0, the value of the count output Sdc is set to HI and the operation is stopped.

  The count output Sdc of the subtraction counter 490 is connected to one input of the exclusive OR gate 472. Further, a recorded object presence / absence signal Spe is inputted to the other input of the exclusive OR gate 472. The output of the exclusive OR gate 472 is coupled to one input of the AND gate 470 via an inverter 474 that outputs a counter signal Sc. The side end signal Sw is input to the other input of the AND gate 470. The output of the AND gate 470 becomes a signal outside the recording object.

FIG. 14 is a timing chart 44 for explaining the operation of the electronic circuit 43 shown in FIG. As shown in the figure, at the timing _{T 21,} the initialization signal Sr by transitioning to LOW from HI, the pulse generator 492 and the subtraction counter 490 is initialized, respectively. As a result, the value of the output OUT of the pulse generator 492 becomes LOW. Further, the value of the count output Sdc of the subtraction counter 490 becomes HI. However, since the value of the recording object presence / absence signal Spe is LOW at this time, the value of the counter signal Sc that is the output of the inverter 474 that inverts the output of the exclusive OR gate 472 is LOW. Therefore, regardless of the value of the side edge signal Sw output from the recorded object width detecting means 430, the value of the signal outside the recorded object is LOW.

Then, at timing T _22, the recording sheet 170 is charged recording material presence or absence signal Spe transitions to HI, the output of the discharge pulse number storing means 484 while a high impedance, the carrier pulse number storing unit 482 The stored pulse number Data1 is set as the count initial value in the Data input of the subtraction counter 490. Further, the output OUT of the pulse generator 492 generates a pulse and inputs it to the START input of the subtraction counter 490. Accordingly, the subtraction counter 490 performs subtraction counting for each movement distance pulse Ppf supplied from the movement distance detection means 412 using the set Data 1 as an initial count value. Also, the count output Sdc of the subtraction counter 490 transitions to LOW.

When the count value becomes 0 progressed subtraction count in the down counter 490, at the timing _{T 23,} the value of the count output Sdc transits to HI. At this time, since the value of the recorded object presence / absence signal Spe is HI, the counter signal Sc transits to HI. Accordingly, the AND gate 470 outputs an output having the same value as the side end signal Sw as a signal outside the recording medium.

At timing T ₂₄ , when the recorded object presence / absence signal Spe transitions to LOW, the output of the carrier pulse number storage unit 482 becomes high impedance, while the number of pulses stored in the discharge pulse number storage unit 484 becomes Data 2. It is set as the initial count value in the Data input of the subtraction counter 490. At the same time, the output OUT of the pulse generator 492 generates a pulse and inputs it to the START input of the subtraction counter 490. Accordingly, the subtraction counter 490 performs subtraction counting for each movement distance pulse Ppf supplied from the movement distance detection means 412 using the set Data 2 as an initial count value. Also, the count output Sdc of the subtraction counter 490 transitions to LOW.

When the count value becomes 0 progressed subtraction count in the down counter 490, at the timing _{T 25,} the value of the count output Sdc transits to HI. At this time, since the value of the recorded object presence / absence signal Spe is LOW, the counter signal Sc shifts to LOW. Accordingly, the output of the AND gate 470 outputs a signal outside the recorded product having a value of LOW regardless of the value of the side end signal Sw.

  As described above, the signal outside the recording object output from the electronic circuit 43 changes depending on whether or not the recording sheet 170 exists immediately below the nozzle plate 166 in both the conveyance direction and the width direction of the recording sheet 170. To do. Therefore, by controlling the switching unit 400 based on the value of the signal outside the recording object, the connection of the rib electrode 156 that is the potential control electrode can be appropriately switched to the positive side or the negative side of the potential difference generating unit 330. .

  FIG. 15 is a flowchart F100 showing a processing procedure when the function of the electronic circuit 43 shown in FIG. 13 is realized by software in the recording apparatus on which the microprocessor is mounted. As shown in the figure, when the operation of the ink jet recording apparatus 10 is started, first, the values of the respective units are initialized by an initialization signal (S101). At this time, the value of the output signal to be recorded is also LOW (S102).

  Subsequently, the recorded object presence / absence signal Spe output from the recorded object detection means 420 is monitored to wait for the recording paper 170 to be loaded (S103: NO). When the recording paper 170 is loaded and the recording material detection means 420 detects the arrival of the leading edge of the recording paper 170 (S103: YES), the distance from the recording material detection means 420 to the feeding side end of the row of the openings 168 The movement number pulse Ppf is subtracted and counted using the number of pulses Data1 corresponding to (1) as an initial count value (S104), and the process waits for the count value to become zero (S105: NO). When the count value becomes 0 (S105: YES), the leading edge of the recording paper 170 reaches the feeding side end of the row of openings 168, and the recording operation is started. The end signal Sw is output as an external signal to be recorded (S106).

  At this time, the recorded object presence / absence signal Spe output from the recorded object detection unit 420 is monitored, and the process waits for the trailing edge of the recording paper 170 to pass through the recorded object detection unit 420 (S107: NO). When it is detected that the trailing edge of the recording paper 170 has passed the recording material detection means 420 (S107: YES), the number of pulses corresponding to the distance from the recording material detection means 420 to the discharge side edge of the 168 rows of openings. Data 2 is set as the initial count value, and the movement distance pulse Ppf is subtracted (S108), and the process waits for the count value to become 0 (S109: NO). When the count value becomes 0 (S109: YES), the trailing edge of the recording paper 170 passes just below the discharge side edge of the opening 168 row, and thus the signal outside the recording object is fixed to LOW (S110). Thus, the recording operation for one recording paper 170 is completed.

  As described in detail above, this liquid ejecting apparatus can actively collect ink mist charged with the same polarity as the nozzle plate to reduce the generation of aerosol, and at the same time, recording paper caused by charging of the recording material The contamination of 170 can also be suppressed. Further, the same function can be realized in the existing liquid ejecting apparatus by combining the potential difference generating means and the wiring connecting the potential difference generating means to the nozzle plate and the recording medium as a potential control unit.

  In the above embodiment, the specific configuration has been described by taking the ink jet recording apparatus 10 as an example. However, the liquid ejecting apparatus may be, for example, a color material ejecting apparatus or an organic EL display in the manufacture of a color filter for a liquid crystal display. In addition, it can be implemented as an electrode forming device in the manufacture of FED (surface emitting display), a sample ejecting head used for biochip manufacturing, a sample ejecting head as a precision pipette, a device for drawing pictures, characters, etc. However, it is not limited to these.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. In addition, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1 is a perspective view showing an overview of an inkjet recording apparatus 10 as a whole. FIG. 3 is a perspective view showing an internal mechanism 20 extracted from the ink jet recording apparatus 10. Sectional drawing which shows the structure of the electric field generation mechanism 31 which concerns on one embodiment. The schematic diagram explaining operation | movement of the electric field generation | occurrence | production mechanism 31 in one state. The schematic diagram explaining operation | movement of the electric field generation mechanism 31 in another state. Sectional drawing which shows the structure of the electric field generation mechanism 32 which concerns on other embodiment. FIG. 6 is a cross-sectional view showing the structure of another electric field generating mechanism 33. Furthermore, sectional drawing which shows the structure of the other electric field generation mechanism 34. FIG. Furthermore, sectional drawing which shows the structure of the other electric field generation mechanism 35. FIG. Furthermore, sectional drawing which shows the structure of the other electric field generation mechanism 36. FIG. The figure which shows typically the structure of the electronic circuit 41 which controls the switching means 400. FIG. The timing chart 42 for demonstrating operation | movement of the electronic circuit 41. FIG. The figure which shows typically the other structure of the electronic circuit 43 which controls the switching means 400. FIG. The timing chart 44 for demonstrating operation | movement of the electronic circuit 43. FIG. The flowchart F100 which shows the process sequence in the case of implement | achieving the function equivalent to the electronic circuit 43 by software.

Explanation of symbols

10 Inkjet recording device, 20 Internal mechanism, 31, 32, 33, 34, 35, 36 Electric field generating mechanism, 41, 43 Electronic circuit, 110 Upper case, 120 Lower case, 130 Paper support, 140 Discharge tray, 150 Platen, 152 Depressed portion, 154 rib portion, 156 rib electrode, 160 carriage, 162 ink cartridge, 164 recording head, 166 nozzle plate, 168 opening, 170 recording paper, 210 frame, 212, 214 side portion, 220 guide shaft, 230 timing belt 232, 234 Pulley, 236 Carriage motor, 240 Multi-core cable, 250 Electronic circuit, 260 Absorbing member, 262 Waste liquid absorbing member, 270 Cap member, 272 Pump unit, 274 Wiping means, 280 Carrying Feed unit, 282 Conveyance drive roller, 284 Conveyance driven roller, 286 Conveyance motor, 290 Discharge unit, 292 Discharge drive roller, 294 Discharge driven roller, 310 Counter electrode, 320 Short-circuit protection resistance, 330 Potential difference generating means, 340 Ink column, 342 344, ink droplets, 350 conductive brush, 400 switching means, 410 rotary encoder, 412 moving distance detection means, 420 recording object detection means, 422, 474 inverter, 424, 426, 492 pulse generator, 430 recording object width Detection means, 440 initialization input, 450 carrier subtraction counter, 452, 462 logical sum gate, 460 discharge subtraction counter, 470 logical product gate, 472 exclusive logical sum gate, 482 carrier pulse number storage means, 484 discharge pulse number storage means 490 Subtraction Printer

Claims (8)

A liquid ejecting head that has a conductive nozzle plate and ejects liquid from the opening of the nozzle plate toward the recording material while reciprocating on the recording material;
A platen for supporting and positioning the recording material from the back surface at a position facing the nozzle plate in a direction in which the liquid is ejected, and from the recording material facing the nozzle plate in a direction in which the liquid is ejected. And a counter electrode disposed far away,
A potential control electrode electrically coupled to the recording material supported on the platen;
One end connected to the counter electrode, the other end connected to the nozzle plate, and a potential difference generating means for generating an electric field between the nozzle plate and the counter electrode,
When the recording object exists directly under the nozzle plate, the potential control electrode is connected to the one end of the potential difference generating means, and when there is an area where the recording object does not exist immediately under the nozzle plate, A liquid ejecting apparatus comprising: connection switching means for connecting a potential control electrode to the other end of the potential difference generating means.   The potential control electrode is provided on a platen that supports and positions the recording material from below at a position facing the liquid ejecting head, and is disposed on a surface opposite to the surface on which the liquid is ejected. The liquid ejecting apparatus according to claim 1, comprising an abutting electrode member.   The potential control electrode sandwiches the recording object together with a conveyance driving roller that is rotationally driven in contact with the recording object so as to convey the recording object in a direction intersecting the reciprocation direction, and the conveyance driving roller. The liquid ejecting apparatus according to claim 1, further comprising at least one of a transport driven roller rotated by the transport driving roller.   The potential control electrode sandwiches the recording material together with a discharge driving roller that is rotationally driven in contact with the recording material to discharge the recording material in a direction intersecting the reciprocating direction, and the discharge driving roller. The liquid ejecting apparatus according to claim 1, further comprising at least one of a discharge driven roller rotated by the discharge driving roller.   The potential control electrode sandwiches the recording object together with a conveyance driving roller that is rotationally driven in contact with the recording object so as to convey the recording object in a direction intersecting the reciprocation direction, and the conveyance driving roller. And at least one of the transport driven rollers rotated by the transport drive roller, and a discharge drive that is rotationally driven in contact with the record to eject the record in a direction crossing the reciprocating direction. The liquid ejecting apparatus according to claim 1, further comprising at least one of a discharge driven roller that is rotated by the discharge drive roller while sandwiching the recording material together with the roller and the discharge drive roller.   The liquid ejecting apparatus according to claim 1, wherein the potential control electrode includes a conductive electrode member that contacts the recording object. A recording head having a conductive nozzle plate, and ejecting ink from the opening of the nozzle plate toward the recording material while reciprocating on the recording material;
A platen that supports and positions the recording material from the back surface at a position facing the nozzle plate in the direction in which the ink is ejected, and from the recording material that opposes the nozzle plate in the direction in which the ink is ejected. And a counter electrode disposed far away,
A potential control electrode electrically coupled to the recording material supported on the platen;
One end coupled to the counter electrode, the other end to the nozzle plate, and a potential difference generating means for generating an electric field between the nozzle plate and the counter electrode;
When the recording object exists directly under the nozzle plate, the potential control electrode is connected to the one end of the potential difference generating means, and when there is an area where the recording object does not exist immediately under the nozzle plate, A recording apparatus comprising: connection switching means for connecting a potential control electrode to the other end of the potential difference generating means. A liquid ejecting head that has a conductive nozzle plate and ejects liquid from the opening of the nozzle plate toward the recording material while reciprocating on the recording material;
An electric field generating unit mounted on a liquid ejecting apparatus including a platen that supports and positions the recording object from the back surface at a position facing the nozzle plate in a direction in which the liquid is ejected;
A counter electrode disposed farther than the recording material facing the nozzle plate in a direction in which the liquid is ejected;
A potential control electrode electrically coupled to the recording material supported on the platen;
One end coupled to the counter electrode, the other end to the nozzle plate, and a potential difference generating means for generating an electric field between the nozzle plate and the counter electrode;
When the recording object exists directly under the nozzle plate, the potential control electrode is connected to the one end of the potential difference generating means, and when there is an area where the recording object does not exist immediately under the nozzle plate, An electric field generating unit comprising connection switching means for connecting a potential control electrode to the other end of the potential difference generating means.

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