Recording device

Abstract

Conventionally, no particular consideration has been given to problems caused by ozone inside the device. For example, there is a risk that ozone may contaminate the water-repellent film on the surface of the recording head, resulting in poor ink ejection. [Solution] The device comprises a recording head that records on a medium, a conveying belt that has an adsorption surface that adsorbs the medium and transports the medium to a position opposite the recording head, a first charging means that contacts the conveying belt and frictionally charges the adsorption surface, and a second charging means that charges the adsorption surface by applying a voltage to the conveying belt, and is characterized in that the control means that switches between charging the adsorption surface by the first charging means and charging the adsorption surface by the second charging means switches between charging the adsorption surface by the first charging means and charging the adsorption surface by the second charging means depending on the state of the surface of the medium that contacts the adsorption surface.

Description

Technical Field

[0001] The present invention relates to a recording apparatus that records on a medium.

Background Art

[0002] In a recording apparatus typified by a printer, a configuration may be adopted in which a medium typified by a recording paper is conveyed using a conveyance belt. Further, in such a configuration, a configuration may be used in which the medium is adsorbed to the conveyance belt by charging the conveyance belt (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the process of charging the conveyance belt, ozone may be generated. Depending on the amount of generation, a filter may be provided to prevent leakage of ozone outside the apparatus. However, conventionally, the problems caused by ozone inside the apparatus have not been particularly considered. For example, the water-repellent film on the surface of the recording head may be contaminated by ozone, leading to poor ink ejection.

Means for Solving the Problems

[0005] To solve the above problems, the recording apparatus of the present invention includes a recording head that performs recording on a medium, a conveyance belt that has an adsorption surface for adsorbing the medium and conveys the medium at a position facing the recording head, a first charging means that contacts the conveyance belt and triboelectrically charges the adsorption surface, a second charging means that charges the adsorption surface by applying a voltage to the conveyance belt, and a control means that controls the first charging means and the second charging means. The control means is characterized by switching between charging of the adsorption surface by the first charging means and charging of the adsorption surface by the second charging means according to the state of the surface of the medium that contacts the adsorption surface.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0007] The present invention will be outlined below. A recording apparatus according to a first aspect of the present invention includes a recording head that performs recording on a medium, a conveyance belt that has an adsorption surface for adsorbing the medium and conveys the medium at a position facing the recording head, first charging means that contacts the conveyance belt and triboelectrically charges the adsorption surface, and second charging means that charges the adsorption surface by applying a voltage to the conveyance belt. A control means for switching between the charging of the adsorption surface by the first charging means and the charging of the adsorption surface by the second charging means switches between the charging of the adsorption surface by the first charging means and the charging of the adsorption surface by the second charging means according to the state of the surface of the medium in contact with the adsorption surface.

[0008] According to this aspect, the recording apparatus includes first charging means for triboelectrically charging an adsorption surface that adsorbs a medium in contact with a conveyance belt, and second charging means for charging the adsorption surface by applying a voltage to the conveyance belt. The control means switches between the charging of the adsorption surface by the first charging means and the charging of the adsorption surface by the second charging means according to the state of the surface of the medium in contact with the adsorption surface. Therefore, by minimizing the charging of the adsorption surface by the second charging means, it is possible to achieve both suppression of ozone generation and appropriate adsorption of the medium to the adsorption surface. Also, by selecting the first charging means, power consumption can be suppressed.

[0009] A second aspect of the present invention is characterized in that, in the first aspect, when the control means adsorbs the surface of a medium on which recording has not been performed to the adsorption surface, it selects the charging of the adsorption surface by the first charging means, and when it adsorbs the surface of a medium on which recording has already been performed to the adsorption surface, it selects the charging of the adsorption surface by the second charging means.

[0010] Particularly when recording is performed by discharging a liquid onto a medium, the surface of the medium onto which the liquid has been discharged, i.e., the surface of the medium on which recording has already been performed, and the surface of the medium onto which the liquid has not been discharged, i.e., the surface of the medium on which recording has not been performed, have different electrical conductivities. The latter, i.e., the surface of the medium on which recording has not been performed, has lower electrical conductivity and is more favorably adsorbed onto the adsorption surface. According to this aspect, when the control means adsorbs the surface of the medium on which recording has not been performed onto the adsorption surface, it selects the charging of the adsorption surface by the first charging means. When adsorbing the surface of the medium on which recording has already been performed onto the adsorption surface, it selects the charging of the adsorption surface by the second charging means. Thus, the medium can be appropriately adsorbed both when adsorbing the surface of the medium on which recording has already been performed and when adsorbing the surface of the medium on which recording has not been performed.

[0011] According to a third aspect of the present invention, in the first or second aspect, the charging of the adsorption surface by the second charging means can be switched between charging by applying a first voltage and charging by applying a second voltage lower than the first voltage. When the control means selects the charging of the adsorption surface by the second charging means, it selects the first voltage in the contact region where the medium contacts the adsorption surface and selects the second voltage in the non-contact region where the medium does not contact the adsorption surface.

[0012] According to this aspect, when the control means selects the second charging means, it selects the first voltage in the contact region where the medium contacts the adsorption surface and selects the second voltage lower than the first voltage in the non-contact region where the medium does not contact the adsorption surface. Therefore, the amount of ozone generation when the second charging means is selected can be suppressed. Note that in this specification, the second voltage includes the meaning of 0V.

[0013] The fourth aspect of the present invention is, in the first or second aspect, the charging of the adsorption surface by the second charging means can be switched between charging by applying a first voltage and charging by applying a second voltage lower than the first voltage, and when the control means selects the charging of the adsorption surface by the second charging means, the first voltage is selected in a region where the front end and the rear end of the medium contact the adsorption surface, and the second voltage is selected in a region where an intermediate portion between the front end and the rear end of the medium contacts. This is characterized by the above.

[0014] According to this aspect, when the control means selects the second charging means, the first voltage is selected in a region where the front end and the rear end of the medium contact the adsorption surface, and the second voltage lower than the first voltage is selected in a region where an intermediate portion between the front end and the rear end of the medium contacts. Therefore, the lifting from the adsorption surface can be favorably suppressed by selecting the first voltage at the front end and the rear end of the medium, and the amount of ozone generation can be suppressed by selecting the second voltage in a region where an intermediate portion between the front end and the rear end of the medium contacts. In addition, in this specification, the second voltage means including 0V.

[0015] The fifth aspect of the present invention is, in the first aspect, the control means is characterized by switching between the first charging means and the second charging means according to the recording density of the surface of the medium in contact with the adsorption surface.

[0016] According to this aspect, since the control means switches between the first charging means and the second charging means according to the recording density of the surface of the medium in contact with the adsorption surface, it is possible to achieve both suppression of the amount of ozone generation and appropriate adsorption of the medium to the adsorption surface.

[0017] The sixth aspect of the present invention is, in the first aspect, the control means switches between the first charging means and the second charging means along the conveyance direction according to the recording position of the surface of the medium in contact with the adsorption surface in the conveyance direction of the medium. This is characterized by the above.

[0018] According to this aspect, since the control means switches the first charging means and the second charging means along the conveyance direction according to the recording position in the conveyance direction of the surface of the medium in contact with the adsorption surface, it is possible to achieve both suppression of the ozone generation amount and appropriate adsorption of the medium to the adsorption surface.

[0019] A seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the first charging means and the second charging means charge the adsorption surface to a positive polarity. According to this aspect, in the configuration in which the adsorption surface is charged to a positive polarity, the operational effects of any one of the first to sixth aspects described above can be obtained.

[0020] An eighth aspect of the present invention is characterized in that, in any one of the first to seventh aspects, it includes a static elimination brush capable of contacting the adsorption surface and a switching means for switching whether or not to ground the static elimination brush, and the first charging means is constituted by the static elimination brush in a non-grounded state. According to this aspect, since the static elimination brush, which is a configuration for static elimination, also serves as the first charging means, an increase in cost can be suppressed by reducing the number of parts.

[0021] Hereinafter, the present invention will be specifically described. Hereinafter, as a recording apparatus according to the present invention, an inkjet printer (hereinafter abbreviated as "printer") that performs inkjet recording on recording paper, which is an example of a medium, will be taken as an example. Note that in the inkjet method, there are various forms such as a type in which an ink cartridge is mounted on a carriage and a type in which an ink storage unit is provided outside the carriage and the ink storage unit and the carriage are connected by an ink tube, and the present invention is applicable to any form. Note that the printer 1 according to the present embodiment is a type in which an ink storage unit is provided outside the carriage and the ink storage unit and the carriage are connected by an ink tube. In addition, there are a type in which a recording head that discharges ink moves in the paper width direction and a type in which the recording head is formed to cover the paper width direction and does not move, and the printer 1 according to the present embodiment is the latter type.

[0022] In each figure, the x-y-z coordinate system shown has the x-direction being the depth direction of the apparatus and the paper width direction, the y-direction being the width direction of the apparatus, and the z-direction being the height direction of the apparatus and the direction of gravity. Note that the direction in which the recording paper is conveyed is referred to as "downstream", and the opposite is referred to as "upstream".

[0023] Hereinafter, the overall configuration of the printer 1 will be outlined while referring to FIGS. 1 and 2. In FIG. 1, the printer 1 includes a scanner unit 3 above the apparatus main body 2A that performs recording on the recording paper, and additional units 2B and 2C below the apparatus main body 2A. The apparatus main body 2A includes a paper cassette 10A, the additional unit 2B includes a paper cassette 10B, and the additional unit 2C includes a paper cassette 10C. These additional units 2B and 2C are optional units for increasing the number of sheets of paper that can be accommodated, and can be arbitrarily attached to the apparatus main body 2A.

[0024] Reference numeral 5 is an operation unit that performs various operations of the printer 1, and reference numeral 4 is a tray that receives the recording paper on which recording is performed and discharged. More specifically, it is a face-down paper discharge tray that receives the recording paper discharged with the most recently recorded recording surface facing down. Also, reference numeral 35 is a paper feed unit, and it can be opened and closed with respect to the apparatus main body 2A by rotating about a rotation fulcrum (not shown).

[0025] Reference numeral 6 is an opening / closing cover that constitutes the paper feed unit 35, and is configured to be swingable about a swing axis 6a (FIG. 2), and can be opened in the directions indicated by arrows e and f. In FIG. 1, the virtual line and reference numeral 6-1 indicate the opening / closing cover during the opening / closing process. An insertion tray 41 (FIG. 2) is provided inside the opening / closing cover 6. The insertion tray 41 rotates about a swing axis 41a and can be opened and closed together with the opening / closing cover 6. Note that the insertion tray 41 shown in FIG. 2 is in the storage posture, and can be opened in the clockwise direction from the state of FIG. 2 and is inclined upward to enable manual paper feeding.

[0026] Further, in the printer 1, the side where the operation unit 5 is disposed is the front side of the apparatus, and the side where the opening / closing cover 6 is provided is the right side surface of the apparatus. That is, the feeding, conveying, and discharging of the recording paper in the printer 1 are performed along the left-right direction of the apparatus.

[0027] Next, while referring to FIG. 2, the paper conveyance path in the printer 1 will be outlined. The printer 1 has these three paper feeding paths: a feeding path from the paper cassette 10A (see the cassette feeding locus S1), feeding paths from the paper cassettes 10B and 10C (not shown in FIG. 2) (see the additional cassette feeding locus S2), and a feeding path from the manual tray 41 on which the recording paper is placed (see the manual feeding path S3).

[0028] The printer 1 also has these two paper discharging methods: face-up discharging (see the face-up discharging locus T1) in which the recording surface on which recording was most recently performed is discharged upward, and face-down discharging (see the face-down discharging locus T2) in which the recording surface on which recording was most recently performed is discharged downward.

[0029] In FIG. 2, reference numeral 7 indicates a face-up paper discharge tray that receives the recording paper discharged face-up. This face-up paper discharge tray 7 can take the stored state shown in FIG. 2 and an open state (not shown) by rotating about the rotation axis 7a.

[0030] The printer 1 is provided with these five paper conveyance paths: a recording conveyance path R1, a switchback path R2, a reversal path R3, a face-down discharge path R4, and further a face-up discharge path R5.

[0031] In FIG. 2, reference numeral 33 indicates a flap (path switching member) driven by a drive source (not shown), and switches between the state shown by the solid line and reference numeral 33 in FIG. 2 and the state shown by the virtual line and reference numeral 33-1.

[0032] When the flap 33 is in the state shown by the solid line in Fig. 2, the recording paper is guided to the face-down discharge path R4 and is face-down discharged as shown by the face-down discharge locus T2. When the flap 33 is in the state of the phantom line and the reference numeral 33-1 in Fig. 2, the recording paper is guided to the face-up discharge path R5 and is face-up discharged as shown by the face-up discharge locus T1. Hereinafter, the paper feed path up to the registration roller pair 17 in Fig. 2 will be further described.

[0033] The paper cassette 10A detachably provided on the apparatus main body 2A is provided with a hopper 11. By swinging the hopper 11 about the shaft 11a, the recording paper accommodated in the paper cassette 10A comes into contact with and separates from a feed roller 12 that is rotationally driven by a motor (not shown).

[0034] The recording paper fed out from the paper cassette 10A by the feed roller 12 is separated (double-feed prevention) by passing through the nip position of the separation roller pair 13, and reaches the registration roller pair 17 under the feeding force from the conveyance roller pair 14. The additional units 2B and 2C (Fig. 1) located under the apparatus main body 2A are also provided with a feed roller 12 and a separation roller pair 13. The recording paper fed out from each paper cassette reaches the registration roller pair 17 under the feeding force from the conveyance roller pair 14 shown in Fig. 2. Also, a feed roller 15 and a separation roller 16 are provided in the paper feed path (manual feed path S3) from the manual feed tray 41. The recording paper set on the manual feed tray 41 reaches the registration roller pair 17 by the rotation of these rollers.

[0035] Hereinafter, the paper conveyance path downstream from the registration roller pair 17 will be described with reference to Fig. 3. Note that in Fig. 3, the description is made on the premise that the recording paper is face-down discharged through the face-down discharge path R4.

[0036] First, the rollers provided in each paper conveyance path will be described. In FIG. 3, reference numeral 17 denotes a resist roller pair, reference numerals 20 to 24 and 26 to 29 all denote conveyance roller pairs for conveying the recording paper, and reference numeral 25 denotes a discharge roller pair for discharging the recording paper. One roller of each roller pair other than the resist roller pair 17 and the conveyance roller pair 26 is denoted by reference numeral F, and the other roller is denoted by reference numeral G. Note that the discharge roller pair 25 provided at the most downstream of the face-down discharge path R4 constitutes a discharge unit that discharges the recording paper from the face-down discharge path R4.

[0037] Roller F is a drive roller driven by a motor (not shown), and is, for example, a rubber roller provided in a plurality at appropriate intervals in the paper width direction. Roller G is a driven roller that can nip the recording paper with roller F by urging means (not shown) and rotates in a driven manner in contact with the recording paper, and is provided in a pair with roller F at appropriate intervals in the paper width direction. Roller G is a gear roller having a plurality of teeth on its outer periphery, and suppresses white dropout and transfer of the ink on the already recorded surface by making point contact with the recording surface. Note that, in addition to constituting each conveyance roller pair, the driven roller G is provided at an appropriate position on the paper conveyance path, and is particularly provided on the side in contact with the most recent recording surface.

[0038] On the other hand, the resist roller pair 17 and the conveyance roller pair 29 have a different configuration from the above-described roller pairs. Specifically, the conveyance roller pair 29 includes a drive roller 29a that is rotationally driven, and a driven roller 29b that is pressed toward the drive roller 29a and can rotate in a driven manner. Among these, the driven roller 29b is a resin roller having a smooth outer peripheral surface.

[0039] The resist roller pair 17 includes a driving roller 17a that is rotationally driven and a driven roller 17b that is rotatable following and is pressed toward the driving roller 17a by a biasing means (not shown). Among these, the driving roller 17a is a roller having fine irregularities on its outer periphery, and the driven roller 17b is a resin roller having a smooth outer peripheral surface. A plurality of driving rollers 17a are provided at appropriate intervals along the axial direction with respect to the rotation axis 17c (FIG. 4). Similarly, a plurality of driven rollers 17b are provided at appropriate intervals along the axial direction with respect to the rotation axis 17d (FIG. 4).

[0040] Between each of the above-described rollers, the recording paper is guided by upper and lower guide members. In FIGS. 2 to 4, in order to avoid complication of the drawing, the guide members are not labeled, but the thick lines connecting between the rollers indicate the above-described guide members. Further, the illustration of the above-described guide members is appropriately omitted after FIG. 4.

[0041] Next, the recording conveyance path R1 as the first conveyance path passes under a recording head 8 as a recording unit for performing recording on the recording paper and extends upstream and downstream thereof. In this embodiment, for convenience, the recording conveyance path R1 is generally from position M1 to position M2 in FIG. 3. In the recording conveyance path R1, the paper receives a feeding force from the resist roller pair 17 and the belt unit 18.

[0042] In this embodiment, the recording head 8 as a recording means is a recording head (so-called line head) provided such that nozzles for discharging ink cover the entire width direction of the paper, and is configured as a recording head capable of performing recording on the entire paper width without moving in the paper width direction.

[0043] The switchback path R2 as the second conveyance path is a conveyance path that connects to the recording conveyance path R1. After feeding the recording paper that has passed under the recording head 8 (in the left direction in FIG. 3), it is switchbacked and conveyed in the direction opposite to the feeding direction (in the right direction in FIG. 3). It is located on the inner side of the curve with respect to the face-down discharge path R4 described later. In this embodiment, for convenience, the switchback path R2 is generally to the left of the position M3 in FIG. 3. In the switchback path R2, the recording paper receives a feeding force from the pair of conveyance rollers 26.

[0044] The inversion path R3 as the third conveyance path is a conveyance path that connects to the switchback path R2. The recording paper conveyed in the reverse direction (in the right direction in FIG. 3) is inverted by bypassing the upper side of the recording head 8 and merged at the upstream position of the recording head 8 in the recording conveyance path R1 (in this embodiment, the upstream position of the registration roller pair 17). In this embodiment, for convenience, the inversion path R3 is generally the path from the position M3 to the position M4 in FIG. 3. In the inversion path R3, the recording paper receives a feeding force from the pair of conveyance rollers 27, 28, 29.

[0045] The face-down discharge path R4 as the fourth conveyance path is a conveyance path that connects to the recording conveyance path R1. It is a path for bending and inverting the recording paper that has passed under the recording head 8 with the face facing the recording head 8 inward and discharging it. In this embodiment, for convenience, the face-down discharge path R4 is generally to the left of the position M2 in FIG. 3. In the face-down discharge path R4, the recording paper receives a feeding force from the pair of conveyance rollers 20, 21, 22, 23, 24, and the pair of discharge rollers 25.

[0046] In addition, at the connection parts of each conveyance path, a first flap 31 and a second flap 32 are provided as path switching members for switching the conveyance path. The first flap 31 is swingable about a swing fulcrum 31a by receiving a driving force from a driving means (not shown). The second flap 32 is provided so as to be engageable with the first flap 31 via an engaging part (not shown), and swings about a swing fulcrum 32a in response to the swing of the first flap 31. These flaps set the path along which the recording paper advances.

[0047] Subsequently, while referring to FIG. 4, the belt unit 18 and its peripheral configuration will be described in detail. The conveyor belt 18c constituting the belt unit 18 is an endless belt made of a base material such as urethane or rubber and containing a conductive material as required to adjust the resistance value. It is wound around the upstream drive pulley 18a and the downstream driven pulley 18b, and a predetermined tension is applied by a tensioner (not shown). The drive pulley 18a is rotationally driven by a motor 37 controlled by the control unit 9. When the drive pulley 18a is rotationally driven, the conveyor belt 18c operates, and the recording paper adsorbed to the conveyor belt 18c is conveyed.

[0048] Support plates 45 and 46 are provided inside the conveyor belt 18c, and the conveyor belt 18c is provided in a state where its inward deflection is restricted by these support plates 45 and 46. The support plates 45 and 46 are formed of a conductive material such as metal and are grounded in this embodiment.

[0049] A charging roller 44 is provided at a position facing the drive pulley 18a with the conveyor belt 18c interposed therebetween. The printer 1 according to this embodiment includes a first charging means and a second charging means as means for charging the conveyor belt 18c, and the charging roller 44 constitutes the second charging means.

[0050] The charging roller 44 is in contact with the outer surface of the conveyor belt 18c and rotates passively in response to the operation of the conveyor belt 18c. A power supply device 49 for applying a DC voltage to the charging roller 44 is connected to the charging roller 44, and thereby the charging roller 44 supplies electric charges to the portion in contact with the conveyor belt 18c. The power supply device 49 is controlled by the control unit 9 to switch on and off the voltage application to the charging roller 44 and to switch the voltage applied to the charging roller 44. In this embodiment, the charging roller 44 supplies positive charges to the conveyor belt 18c and charges the outer surface of the conveyor belt 18c to a positive polarity. That is, the outer surface of the conveyor belt 18c becomes the adsorption surface 18d for adsorbing the recording paper.

[0051] A driven roller 19a is provided above the driving pulley 18a with the conveyor belt 18c interposed therebetween. Similarly, a driven roller 19b is provided above the driven pulley 18b with the conveyor belt 18c interposed therebetween. The recording paper conveyed by the conveyor belt 18c is pressed against the conveyor belt 18c by these driven rollers 19a and 19b. The driven rollers 19a and 19b are made of a conductive material such as metal and are grounded.

[0052] A static elimination brush 43 that contacts the recording paper is provided upstream of the recording head 8, and the static elimination brush 43 removes the electric charges on the upper surface of the recording paper or the outer surface of the conveyor belt 18c, that is, the adsorption surface 18d. More specifically, when electric charges are applied to the adsorption surface 18d of the conveyor belt 18c by the charging roller 44, electric charges of the opposite polarity to the surface in contact with the adsorption surface 18d are generated on the recording paper in contact with the adsorption surface 18d, and further electric charges of the opposite polarity to those charges are generated on the opposite surface of the recording paper, that is, the recording surface. The electric charges on the recording surface side are removed by the static elimination brush 43, and as a result, only the electric charges on the side of the recording paper in contact with the conveyor belt 18c remain, and the recording paper is adsorbed to the adsorption surface 18d. The static elimination brush 43 may be made of any material that can remove electric charges from the recording paper and the conveyor belt 18c, and can be formed of a resin material such as conductive nylon, for example.

[0053] Also, the static eliminator brush 43 is also used for static elimination of the conveyor belt 18c. The static eliminator brush 43 is connected to a switching unit 48 as switching means, and the switching unit 48 switches between a state where the static eliminator brush 43 is grounded, that is, earthed, and a state where it is not grounded under the control of the control unit 9.

[0054] A cleaning blade 47 is provided below the belt unit 18. The cleaning blade 47 is provided so as to sandwich the conveyor belt 18c between it and the support plate 46, and by wiping the adsorption surface 18d of the conveyor belt 18c, it removes ink, foreign matter, etc. adhering to the adsorption surface 18d. The cleaning blade 47 can be formed of a resin material such as a PET (polyethylene terephthalate) film, for example. Incidentally, the cleaning blade 47 can also be provided so as to be switchable between a state of being in contact with the conveyor belt 18c and a state of being separated from the conveyor belt 18c. Also, the cleaning blade 47 can be connected to a switching unit that switches between a grounded state and a non-grounded state, similar to the above-described static eliminator brush 43, so that it can be used as the first charging means described later in addition to or instead of the static eliminator brush 43.

[0055] The above-described motor 37, power supply device 49, switching unit 48, etc. are connected to the control unit 9 as control means. The control unit 9 acquires recording data, which is data for performing recording generated by a printer driver operating on an external computer (not shown) or a printer driver provided in the control unit 9, and based on the recording data, controls each mechanism part including the recording head 8 and motors for recording paper conveyance. Also, the control unit 9 performs necessary control based on the detection states of various sensors. The sensor 36 shown in FIG. 4 is provided between the resist roller pair 17 and the belt unit 18, and sends a detection signal to the control unit 9, whereby the control unit 9 can detect the passage of the leading end and the trailing end of the recording paper at the position of the sensor 36. For example, when the control unit 9 detects the passage of the leading edge of the recording paper at the position of the sensor 36, it can determine the start timing of charging the adsorption surface 18d by the charging roller 44. Also, when it detects the passage of the trailing edge of the recording paper, it can determine the end timing of charging the adsorption surface 18d by the charging roller 44.

[0056] In this embodiment, the registration roller pair 17 and the drive pulley 18a use a motor 37, which is a common drive source, as the drive source. The paper conveyance speed by the registration roller pair 17 and the paper conveyance speed by the belt unit 18 are determined by the reduction ratio of the gear group that transmits power from the motor 37 to the registration roller pair 17 and the drive pulley 18a, etc. However, the registration roller pair 17 and the drive pulley 18a may be driven by separate motors respectively.

[0057] Subsequently, with reference to FIGS. 4 to 6, the switching of the charging means will be described. As described above, the printer 1 includes a first charging means and a second charging means as means for charging the adsorption surface 18d of the conveyance belt 18c. The first charging means is a means for triboelectric charging the adsorption surface 18d, and the second charging means is a means for charging the adsorption surface 18d by applying a voltage to the conveyance belt 18c. Then, the control unit 9 switches between charging the adsorption surface 18d by the first charging means and charging the adsorption surface 18d by the second charging means according to the state of the surface of the recording paper in contact with the conveyance belt 18c. Hereinafter, charging the adsorption surface 18d by the first charging means may be referred to as triboelectric charging, and charging the adsorption surface 18d by the second charging means may be referred to as voltage application charging.

[0058] In this embodiment, the second charging means is constituted by the charging roller 44 as described above, and the charging roller 44 charges the adsorption surface 18d to a positive polarity. The first charging means is constituted by the static elimination brush 43 in this embodiment, and the static elimination brush 43 charges the adsorption surface 18d to a positive polarity. The switching unit 48 connected to the static elimination brush 43 can switch between a state where the static elimination brush 43 is grounded and a state where it is not grounded under the control of the control unit 9. In the state where it is not grounded, when the operating conveyor belt 18c contacts the static elimination brush 43, the adsorption surface 18d becomes triboelectrically charged. The static elimination brush 43 is preferably made of a material that is on the negative side of the triboelectric series compared to the material forming the conveyor belt 18c in order to positively charge the adsorption surface 18d. As described above, since the static elimination brush 43, which is a configuration for static elimination, also serves as the first charging means, an increase in cost can be suppressed by reducing the number of parts.

[0059] Still, even when the switching unit 48 is in a state where the static elimination brush 48 is grounded, if the static elimination of the adsorption surface 18d by the static elimination brush 48 is not completely performed and a certain amount of charge remains on the adsorption surface 18d, triboelectric charging may be performed with the switching unit 48 in a state where the static elimination brush 48 is grounded. Therefore, a configuration omitting the switching unit 48 can also be adopted.

[0060] And by selecting triboelectric charging, the control unit 9 can prevent the generation of ozone caused by the charging process of voltage application charging while adsorbing the recording paper onto the adsorption surface 18d. In other words, by minimizing the use of voltage application charging, it is possible to achieve both suppression of ozone generation and appropriate adsorption of the recording paper onto the adsorption surface 18d. Also, by selecting triboelectric charging, the power consumption of the printer 1 can be suppressed. Therefore, when using triboelectric charging, voltage application charging is not used. Conversely, when using voltage application charging, triboelectric charging is not used. However, when using voltage application charging, triboelectric charging can also be used in combination.

[0061] The following will be described in more detail with reference to FIG. 5. Before the leading edge of the recording paper reaches the conveyance belt 18c, the control unit 9 determines whether the surface of the recording paper that contacts the adsorption surface 18d has already been a surface on which ink has been ejected, that is, a surface that has already been recorded (step S101). If it is an unrecorded surface on which ink has not yet been ejected (No in step S101), frictional electrification is used (step S104). Here, as shown in FIG. 6, the unrecorded surface is the second surface Sb of the recording paper, that is, the surface opposite to the first surface Sa that first faces the recording head 8, or when the recording paper is inverted without recording on the first surface Sa, the first surface Sa becomes the unrecorded surface.

[0062] Returning to FIG. 5, in step S101, conversely, if the surface of the recording paper that contacts the adsorption surface 18d is a surface that has already been recorded (Yes in step S101), it is determined whether the recording density is equal to or higher than a predetermined threshold value (step S102). If the recording density is less than the predetermined threshold value (No in step S102), frictional electrification is used (step S104). Conversely, if the recording density is equal to or higher than the predetermined threshold value (Yes in step S102), voltage application electrification is used (step S103). And if there is a next recording operation (Yes in step S105), steps S101 and subsequent steps are repeated.

[0063] That is, between the recorded surface on which ink has been ejected and the unrecorded surface on which ink has not been ejected, the latter has lower electrical conductivity than the former and is better adsorbed to the adsorption surface 18d. Also, even if it is a recorded surface, if the recording density is low, it is well adsorbed to the adsorption surface 18d. The recording density here means the area on which ink has been ejected per unit area. In this way, when the control unit 9 adsorbs the unrecorded surface to the adsorption surface 18d, it selects frictional electrification, and when adsorbing the recorded surface to the adsorption surface 18d, it selects voltage application electrification. Thereby, the recording paper can be appropriately adsorbed both when adsorbing the recorded surface and when adsorbing the unrecorded surface. Also, even on the already recorded surface, since the frictional electrification and the voltage application electrification are switched according to the recording density, it is possible to achieve both suppression of the amount of ozone generated by the voltage application electrification and appropriate adsorption of the recording paper to the adsorption surface 18d. Still, the process based on the determination in step S102, that is, the process of switching between frictional electrification and voltage application electrification according to the recording density, may be omitted, and regardless of the recording density, voltage application electrification may always be selected for the already recorded surface.

[0064] The control examples described above can be further modified as follows. (1) The electrification of the adsorption surface 18d by voltage application electrification can be switched between electrification by applying a first voltage and electrification by applying a second voltage lower than the first voltage. When the control unit 9 selects voltage application electrification, the first voltage is selected in the contact area where the recording paper contacts the adsorption surface 18d, and the second voltage is selected in the non-contact area where the recording paper does not contact. This can suppress the amount of ozone generated when voltage application electrification is selected.

[0065] An example of the area on the adsorption surface 18d where the recording paper does not contact is, for example, the area between the preceding recording paper and the next recording paper following it. In FIG. 6, reference symbol P1 indicates the preceding paper, and reference symbol P2 indicates the subsequent paper. The range of the adsorption surface 18d corresponding to the area Wk between the rear end R of the preceding paper P1 and the front end F of the subsequent paper P2 is an example of the area on the adsorption surface 18d where the recording paper does not contact. Also, examples of the area on the adsorption surface 18d where the recording paper does not contact include the entire adsorption surface 18d before the start of the recording job and the entire adsorption surface 18d after the end of the recording job. Still, the second voltage means including 0V.

[0066] FIG. 8 is a flowchart showing an example of the above control. When the suction surface 18d is in contact with the recording paper (Yes in step S201), the control unit 9 selects the first voltage (step S203). When the suction surface 18d is not in contact with the recording paper (No in step S201), the control unit 9 selects a second voltage lower than the first voltage (step S202). The above process is repeated until the recording is completed (step S204). In addition, this control can also be applied to the voltage application charging in step S103 in the control shown in FIG. 5.

[0067] (2) When the control unit 9 selects voltage application charging, as shown in FIG. 6, in the region where the leading end Wf and the trailing end Wr of the recording paper contact the suction surface 18d, the first voltage may be selected, and in the intermediate portion Wc between the leading end Wf and the trailing end Wr of the recording paper, the second voltage may be selected. Thereby, the lifting from the suction surface 18d can be favorably suppressed by selecting the first voltage at the leading end Wf and the trailing end Wr of the recording paper. And ozone generation can be suppressed by selecting the second voltage in the intermediate portion Wc between the leading end Wf and the trailing end Wr. In addition, also in this embodiment, the second voltage means including 0V.

[0068] FIG. 9 is a flowchart showing an example of the above control. When the suction is not at the center of the paper (No in step S301), the control unit 9 selects the first voltage (step S303). When the suction is at the center of the paper (Yes in step S301), the control unit 9 selects a second voltage lower than the first voltage (step S302). The above process is repeated until the recording is completed (step S304). In addition, this control can also be applied to the voltage application charging in step S103 in the control shown in FIG. 5. At this time, the control shown in FIG. 8 can also be further applied.

[0069] (3) The control unit 9 is along the conveyance direction Y according to the recording position in the conveyance direction Y of the surface of the recording paper in contact with the suction surface 18d First voltage and Second voltageIt may be switched as such. For example, in FIG. 6, it is assumed that ink is ejected onto the first surface Sa which is one surface of the recording paper P1. Then, when this recording paper P1 is reversed and the region Wp comes into contact with the adsorption surface 18d as shown in FIG. 7, the first voltage is selected in the region of the adsorption surface 18d where the region Wp is in contact, and the second voltage is selected in the region where the other regions except the region Wp are in contact on the first surface Sa. Thereby, it is possible to achieve both suppression of the ozone generation amount and appropriate adsorption of the recording paper to the adsorption surface 18d.

[0070] FIG. 10 is a flowchart showing an example of the above control. When the area to be adsorbed is a recorded area (Yes in step S401), the control unit 9 selects the first voltage (step S403), and when the area to be adsorbed is an unrecorded area (No in step S401), the control unit 9 selects a second voltage lower than the first voltage (step S402). The above processing is repeated until the recording is completed (step S404). In addition, this control can also be applied to the voltage application charging in step S103 in the control shown in FIG. 5. At this time, the control shown in FIG. 8 can also be further applied.

[0071] In addition, in FIG. 4, a static elimination brush 43 and a charging roller 44 are arranged upstream of the contact start position f of the recording paper in the rotation direction of the conveyor belt 18c. Among these, the distance c from the position e where the charging roller 44 closest to the contact start position f contacts the conveyor belt 18c to the contact start position f is preferably longer than the distance d from the detection position of the sensor 36 to the contact start position f in the paper conveyance path. That is, if the distance c is shorter than the distance d, there is a possibility that the adsorption surface 18d of the conveyor belt 18c is not charged when the leading edge of the paper reaches the contact start position f. However, in this embodiment, since the distance c is longer than the distance d, the adsorption surface 18d is surely charged when the leading edge of the paper reaches the contact start position f. This is particularly suitable when the paper conveyance speed by the resist roller pair 17 is equal to the paper conveyance speed by the conveyance belt 18c.

[0072] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention described in the claims. Needless to say, these are also included in the scope of the present invention.

Explanation of Signs

[0073] 1... Inkjet printer, 2A... Apparatus main body, 2B, 2C... Expansion unit, 3... Scanner unit, 4... Face-down paper discharge tray, 5... Operation unit, 6... Open / close cover, 7... Face-up paper discharge tray, 8... Recording head, 9... Control unit, 10A~10C... Paper cassettes, 11... Hopper, 12... Feeding roller, 13... Separation roller pair, 14... Conveying roller pair, 15... Feeding roller, 16... Separation roller, 17... Resist roller pair, 18... Belt unit, 18a... Driving pulley, 18b... Driven pulley, 18c... Conveyance belt, 18d... Adsorbing surface, 19a, 19b... Driven rollers, 20~29... Conveying roller pairs, 31... First flap, 32... Second flap, 33... Flap, 35... Feeding unit, 36... Sensor, 37... Motor, 43... Static eliminator brush, 44... Charging roller, 45... Support plate, 46... Support plate, 47... Cleaning blade, 48... Switching unit, 49... Power supply device F... Driving roller, G... Driven roller, R1... Recording conveyance path (first conveyance path), R2... Switchback path (second conveyance path), R3... Inversion path (third conveyance path), R4... Face-down discharge path (fourth conveyance path), R5... Face-up discharge path (fourth conveyance path) S1... Cassette feeding locus, S2... Expansion cassette feeding locus, S3... Manual feeding locus, T1... Face-up discharge locus, T2... Face-down discharge locus

Claims

1. A recording head for recording on a medium, a conveyance belt having an adsorption surface for adsorbing the medium and conveying the medium to a position facing the recording head, a contact member that contacts the conveyance belt, voltage application means for charging the adsorption surface by applying a voltage to the conveyance belt, and comprising: the contact member is formed of a material different from the material forming the conveyance belt on the charging row, furthermore, the contact member is a cleaning member for cleaning the conveyance belt, the control means for controlling the charging of the adsorption surface is configured to, according to the recording density of the surface of the medium that contacts the adsorption surface, when the recording density is less than a predetermined threshold value, select a first control for charging the adsorption surface by rotating the conveyance belt with the contact member in contact with the adsorption surface, thereby charging the adsorption surface by friction between the contact member and the conveyance belt, when the recording density is greater than or equal to the threshold value, select a second control for charging the adsorption surface by the voltage application means, when the first control is selected, the voltage application means does not apply a voltage to the conveyance belt, A recording apparatus characterized by the above.

2. In the recording apparatus according to claim 1, the voltage application means includes: a charging roller that is in contact with the conveyance belt and rotates drivenly, a power supply device that switches on and off the voltage application to the charging roller based on the control of the control means, and having: A recording apparatus characterized by the above.

3. In the recording apparatus according to claim 1 or claim 2, the charging of the adsorption surface by the second control is switchable between charging by applying a first voltage and charging by applying a second voltage lower than the first voltage, when the control means selects the second control, select the first voltage in the contact area where the medium contacts the adsorption surface, select the second voltage in the non-contact area where the medium does not contact, A recording apparatus characterized by the above.

4. In the recording apparatus according to claim 1 or claim 2, the charging of the adsorption surface by the second control is switchable between charging by applying a first voltage and charging by applying a second voltage lower than the first voltage, when the control means selects the second control, select the first voltage in the area where the front end and the rear end of the medium contact the adsorption surface, select the second voltage in the area where the middle part between the front end and the rear end of the medium contacts, A recording apparatus characterized by the above.

5. In the recording apparatus according to claim 1 or claim 2, The charging of the adsorption surface by the second control can be switched between charging by applying a first voltage and charging by applying a second voltage lower than the first voltage. When the control means selects the second control, according to the recording position in the conveyance direction of the surface of the medium that contacts the adsorption surface, in the region where the recorded area of the medium contacts the adsorption surface, the first voltage is selected. In the region where the unrecorded area of the medium contacts the adsorption surface, the second voltage is selected. A recording apparatus characterized by the above.

Images