JP2009154985A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device efficiently sucking a recording medium with respect to a belt platen. <P>SOLUTION: This image forming device 1 includes: a paper feeding means 3 feeding the recording medium W stored; a conveying means 11 arranged downstream of the conveying direction of the recording medium W from the paper feeding means 3 and provided with the annular belt platen 9 with both ends fixed to rotating shafts 5, 7; a printing means 13 provided to the conveying means 11 and performing printing on the recording medium W; and a sucking means 17 provided to the conveying means 11 and varying the position of a plurality of sucking portions 15 sucking the recording medium W with respect to the belt platen 9 in response to a size in an orthogonal direction orthogonal to the conveying direction of the recording medium W. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  Patent Document 1 describes a recording medium conveyance mechanism that adsorbs a sheet (recording medium) to a charged conveyance belt (belt platen). In this recording medium transport mechanism, a vacuum mechanism (suction unit) is provided on the upstream side of the transport belt in the transport direction of the paper, so that the transported paper is reliably adsorbed to the transport belt.

Further, in Patent Document 2, a sheet conveyance device in which a vacuum chamber (suction unit) is partitioned into a plurality of chambers (suction units) each provided with a pressure adjusting unit or a vacuum fan along a conveyance direction of a recording medium (recording medium). Is described. In this sheet conveying apparatus, the recording fan is efficiently attracted to the flat plate portion (belt platen) by sequentially starting the vacuum fan corresponding to the chamber where the leading end of the recording body is approached, thereby reducing the noise level. Yes.
JP 2006-327725 A Japanese Patent No. 3690182

  By the way, in Patent Document 1, a vacuum mechanism is provided on the upstream side of the conveyance belt in the conveyance direction of the paper, and the leading end portion in the conveyance direction of the paper is adsorbed to the conveyance belt. For this reason, there is a possibility that the end face of the sheet may be lifted from the conveying belt when the leading end portion of the sheet exceeds the vacuum mechanism.

  On the other hand, in Patent Document 2, a vacuum chamber including a plurality of chambers that are sequentially operated in the conveyance direction of the recording medium is provided, and the leading end portion of the recording medium in the conveyance direction is lifted from the conveyance belt when the recording medium is conveyed. Is prevented.

  However, in Patent Document 2, the operation of the vacuum chamber is controlled with respect to the size of the recording body in the transport direction. However, for any recording body in the orthogonal direction (width direction) orthogonal to any transport direction. However, if the leading end portion of the recording material in the conveyance direction is positioned in the chamber portion of the vacuum chamber, the pressure adjusting means or the vacuum fan in the chamber in that portion is activated. For this reason, suction is performed to a portion where the end of the recording body in the orthogonal direction is not located, and the suction force to the recording body is wasted.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of efficiently sucking a recording medium with respect to a belt platen.

  According to a first aspect of the present invention, there is provided a paper feeding unit that feeds a stored recording medium, and an annular belt platen that is arranged downstream of the paper feeding unit in the conveyance direction of the recording medium and has both ends fixed to a rotating shaft. A conveying unit provided in the conveying unit, a printing unit configured to print on the recording medium, and the recording medium provided in the conveying unit according to a size in an orthogonal direction perpendicular to the conveying direction of the recording medium. The image forming apparatus includes: a suction unit configured to change positions of a plurality of suction units that suction the belt platen.

  A second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the suction means is provided with a plurality of the suction portions in at least three or more rows in the orthogonal direction.

  A third aspect of the present invention is the image forming apparatus according to the second aspect, wherein the suction means is provided with a plurality of at least two rows of the suction portions in the transport direction.

  According to a fourth aspect of the invention, there is provided the image forming apparatus according to the third aspect, wherein the suction unit has a leading end portion in the transport direction of the recording medium positioned at the suction portion in the first row from the upstream in the transport direction. All the suction portions in the orthogonal direction in which the leading ends in the transport direction of the recording medium are located are operated, and the leading ends in the transport direction of the recording medium are moved to the suction portions in the second and subsequent rows from the upstream in the transport direction. In the image forming apparatus, when the position is located, the suction section in the orthogonal direction in which both ends of the recording medium are positioned is operated.

  A fifth aspect of the present invention is the image forming apparatus according to any one of the first to fourth aspects, wherein the belt platen is formed with a plurality of holes, and the recording medium is sucked by the suction means. In the image forming apparatus, an apex at which an end portion in the transport direction of the recording medium intersects an end portion in the orthogonal direction is disposed on a surface formed between the plurality of holes.

  A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, wherein the lid has a plurality of holes formed between the belt platen and the plurality of suction portions. The belt platen is provided with a plurality of holes, and the total surface area of the holes of the lid member is larger than the total surface area of the holes of the belt platen.

  According to the present invention, it is possible to provide an image forming apparatus capable of efficiently sucking a recording medium with respect to a belt platen.

(One embodiment)
An embodiment will be described with reference to FIGS. The transport direction is indicated by the arrow X direction, and the orthogonal direction orthogonal to the transport direction is indicated by the arrow Y direction.

  The image forming apparatus 1 according to the present embodiment includes a sheet feeding unit 3 that feeds a stored recording medium W, and is disposed downstream of the sheet feeding unit 3 in the conveyance direction of the recording medium W, and both ends are connected to rotating shafts 5 and 7. Conveying means 11 having a fixed annular belt platen 9, printing means 13 provided on the conveying means 11 for printing on the recording medium W, and orthogonal to the conveying direction of the recording medium W provided on the conveying means 11 A suction unit 17 that varies the positions of the plurality of suction units 15 that suck the recording medium W against the belt platen 9 according to the size in the orthogonal direction;

  Further, the suction means 17 is provided with a plurality of suction portions 15 in at least three or more rows in the orthogonal direction.

  Furthermore, the suction means 17 is provided with a plurality of suction sections 15 in at least two rows in the transport direction.

  Further, the suction means 17 is arranged in the orthogonal direction where the front end portion 19 in the transport direction of the recording medium W is located when the front end portion 19 in the transport direction of the recording medium W is positioned at the suction portion 15 in the first row from the upstream in the transport direction. When all the suction portions 15 are activated and the leading end portion 19 in the transport direction of the recording medium W is positioned at the suction portion 15 in the second and subsequent rows from the upstream in the transport direction, both end portions 21 and 23 in the orthogonal direction of the recording medium W are The positioned suction part 15 in the orthogonal direction is activated.

  Further, the belt platen 9 is formed with a plurality of holes 25, and when the recording medium W is sucked by the suction means 17, the apex P at which the end portion in the conveyance direction of the recording medium W intersects with the end portion in the orthogonal direction has a plurality of holes. 25 is disposed on a surface 27 formed between the two.

  Further, a lid member 31 having a plurality of holes 29 formed therein is disposed between the belt platen 9 and the plurality of suction portions 15, and the total surface area of the holes 29 of the lid member 31 is the hole of the belt platen 9. It is larger than the total surface area of 25.

  As shown in FIGS. 1 to 11, the paper feed unit 3 includes a paper feed tray 33 and a pickup roller 35. The paper feed tray 33 is formed of a housing, and a plurality of rectangular recording media W are stacked inside. The pickup roller 35 is in contact with the upper surface of the uppermost recording medium W stacked in the paper feed tray 33. The pickup roller 35 is rotationally driven by an actuator such as a motor (not shown) driven by the control of the arithmetic unit 37, so that the recording medium W is placed on the registration unit 39 one by one from the uppermost one. Supply. The recording medium W includes not only paper manufactured from pulp, but also film-like synthetic resin and the like that can be formed by printing or printing pictures or characters.

  The registration unit 39 includes registration rollers 41 and 43 that are in contact with each other. For example, the registration unit 39 temporarily stops the conveyance of the recording medium W fed from the sheet feeding unit 3 to the conveyance path C1, corrects the skew of the recording medium W, and sends the recording medium W to the conveyance unit 11. Is provided. The recording medium W is sandwiched between the registration rollers 41 and 43, and at least one of the registration rollers 41 and 43 is rotationally driven by an actuator such as a registration roller driving motor 45 driven by the control of the arithmetic unit 37. Thus, the recording medium W is sent out to the conveying means 11. In addition, a front end detection sensor 47 that detects the front end 19 in the conveyance direction of the recording medium W is provided between the registration unit 39 and the printing unit 13.

  The transport unit 11 is disposed along the transport path C <b> 2 downstream of the paper feeding unit 3 in the transport direction of the recording medium W, and includes a belt platen 9, a printing unit 13, and a suction unit 17.

  The belt platen 9 is formed in an annular shape, and both ends thereof are fixed to the rollers 5 and 7 (rotating shafts), and a roller 49 is provided at the lower central portion. Any of these rollers 5, 7, 49 may be used. For example, the roller 49 is driven by an actuator such as a belt platen drive motor 51 that is driven by the control of the arithmetic unit 37. The belt platen 9 is provided with a plurality of circular holes 25 at equal intervals with respect to the entire surface 27. A belt hole detection sensor 53 that detects the position of the hole 25 is provided below the belt platen 9. An image is formed on the recording medium W transported to the belt platen 9 by the printing means 13.

  The printing unit 13 is provided above the belt platen 9 and includes cyan, black, magenta, and yellow inkjet heads HC, HK, HM, and HY. The inkjet heads HC, HK, HM, and HY are full line type heads, but are serial types that form images by appropriately moving in the direction orthogonal to the paper surface of the recording medium W under the control of the arithmetic unit 37. The head may be used, or another method may be adopted. When the printing medium 13 forms an image on the recording medium W, the recording medium W is sucked by the suction means 17 with respect to the belt platen 9, and the inkjet heads HC, HK, HM, HY due to the floating of the recording medium W. Contact with is prevented. Further, a width detection device 55 such as a line sensor for detecting the width of the recording medium W (the width in the orthogonal direction perpendicular to the conveyance direction) is provided upstream of the printing unit 13 in the conveyance direction of the recording medium W. . The width detection device 55 may not be provided when the size of the recording medium W stored in the paper feed tray 33 of the paper feed unit 3 is known in advance.

  The suction means 17 is provided below the belt platen 9 (inside the belt platen 9 wound around the rollers 5, 7, 49), and includes a plurality of suction portions 15a to 15i. The suction units 15 a to 15 i include a plurality of suction fans 59 housed in the housing body 57 and a lid member 31 that covers the housing body 57.

  The storage body 57 is formed of a casing, and the inside is partitioned into three rows with respect to the conveyance direction of the recording medium W and three rows with respect to an orthogonal direction orthogonal to the conveyance direction, and a plurality of storage chambers 61 are provided. Yes.

  The suction fans 59a to 59i are housed in the housing chambers 61a to 61i, respectively, and are driven by the control of the arithmetic unit 37. By the operation of the suction fan 59, a negative pressure is generated on the surface 27 of the belt platen 9, and the recording medium W is sucked by the belt platen 9.

  In addition, although the suction fan 59 shows an example of 3 × 3 (suction fans 59a to 59i) having three rows in the conveyance direction of the recording medium W and three rows in the orthogonal direction, the present invention is not limited to this. Alternatively, the storage chamber 61 in which the suction fans 59 are stored may have a configuration in which at least three or more rows are provided in the orthogonal direction and at least two or more rows are provided in the transport direction. For example, the storage chambers 61a to 61o may be provided in the storage body 57 as shown in FIG. In this case, the storage chambers 61a to 61o may be formed so that the transport direction is longer than the orthogonal direction, and two suction fans 59 may be provided in one storage chamber 61. Further, as the number of storage chambers 61 is increased in the orthogonal direction, the larger the number of recording media W can be accommodated.

  The lid member 31 is provided in the upper part of the storage chamber 57 so as to cover the suction fan 59 stored in the storage body 57. A plurality of holes 29 are formed in the lid member 31. A plurality of holes 29 are provided at the bottom of a plurality of oblong slots 63 having a predetermined depth. The total surface area of the holes 29 is set larger than the total surface area of the holes 25 of the belt platen 9. That is, the diameter D2 of the hole 29 is set larger than the diameter D1 of the hole 25 of the belt platen 9. Thereby, the suction force to the recording medium W can be increased. Further, the distance L between the long holes 63 and 63 adjacent to each other in the conveyance direction of the recording medium W is set to be smaller than the diameter D1 of the hole 25 of the belt platen 9. Accordingly, even when the hole 25 of the belt platen 9 is disposed between the long holes 63 and 63, the hole 25 can be positioned on the long holes 63 and 63, and the recording medium W can be sucked.

  As for the shape or arrangement of the plurality of holes 29 provided in the long hole 63, the diameter of the hole 29 arranged upstream in the conveyance direction of the recording medium W is set to the largest diameter and is sequentially increased toward the downstream side. When the diameter of the hole 29 is reduced (see FIG. 10A), the gap between the holes 29 and 29 arranged on the upstream side in the conveyance direction of the recording medium W is reduced and the holes are sequentially moved toward the downstream side. It may be configured to increase the suction force on the suction start side of the recording medium W, such as increasing the distance between 29 and 29 (see FIG. 10B).

  In such a suction means 17, the positions of the suction portions 15a to 15i that are operated in accordance with the width size of the recording medium W (size in the orthogonal direction) are varied. Below, control of the suction means 17 is demonstrated.

  First, when the front end portion 19 in the transport direction of the recording medium W is positioned at the suction portions 15a, 15b, and 15c arranged upstream in the transport direction (see FIG. 11A), the front end portion 19 in the transport direction of the recording medium W. All the suction parts 15a, 15b, 15c in the orthogonal direction where the is located are operated. In addition, when the recording medium W has a width size such that both end portions 21 and 23 in the orthogonal direction of the recording medium W are disposed only in the suction portion 15b, it is only necessary to operate the suction portion 15b.

  Next, when the front end portion 19 in the conveyance direction of the recording medium W is positioned at the suction portions 15d, 15e, and 15f arranged in the second row in the conveyance direction (see FIG. 11B), the orthogonal direction of the recording medium W is reached. Only the suction portions 15d and 15f where the both end portions 21 and 23 are located are operated, and the operation of the suction portion 15b in the first row in the transport direction is stopped.

  Next, when the leading end portion 19 in the conveyance direction of the recording medium W is positioned at the suction portions 15g, 15h, and 15i arranged in the third row in the conveyance direction (see FIG. 11C), the recording medium W is perpendicular to the recording medium W. Only the suction portions 15g and 15i where the both end portions 21 and 23 are located are operated. At this time, the suction portion 15b in the first row in the transport direction and the suction portion 15e in the second row in the transport direction are in a stopped state.

  Then, suction portions 15g, 15h, 15i in which both end portions 19, 65 (front end portion and rear end portion) in the transport direction of the recording medium W are arranged in the third row in the transport direction and suction in the second row in the transport direction are arranged. When the leading end 19 in the transport direction of the second recording medium W is positioned at the suction portions 15a, 15b, and 15c arranged in the first row in the transport direction (see FIG. 11D). )), All the suction portions 15a, 15b, 15c located in the first row in the transport direction are operated, and the suction portions 15d, 15f, 15f, where both end portions 21, 23 in the orthogonal direction of the first recording medium W are located. 15g and 15i are activated.

  Such control of the suction means 17 is sequentially repeated, and when the rear end portion 65 in the transport direction of the finally fed recording medium W passes through the suction portions 15g, 15h, and 15i arranged in the third row in the transport direction. Then, the control of the suction means 17 is finished. Note that suction units other than the operated suction unit are preferably in a stopped state, but may be controlled so as to reduce the suction force more than the operated suction unit.

  The recording medium W thus sucked by the suction unit 17 and having an image formed by the printing unit 13 is conveyed to the paper discharge unit 67. The paper discharge unit 67 includes a paper discharge tray 69 that is arranged along the transport path C3 downstream of the transport unit 11 in the transport direction of the recording medium W and is provided downstream of the transport path C3. The paper discharge tray 69 accommodates a recording medium W formed with a housing and having an image formed thereon by the printing unit 13.

  Note that, for example, conveyance paths C4 and C5 are provided on the upstream side of the registration unit 39 and the upstream side of the paper discharge unit 67, and the recording medium W on which the image is formed by the printing unit 13 is branched to the conveyance path C5 by the branch unit 71. Then, the recording medium W may be reversed and sent from the conveyance path C4 to the registration unit 39, and the recording medium W may be circulated so that the printing unit 13 forms images on both sides of the recording medium W.

  Here, the operation of the suction unit 17 of the image forming apparatus 1 will be described with reference to the flowchart of FIG.

  First, the suction unit 59 is started by controlling the suction fan 59, the leading end detection sensor 47, the belt hole detection sensor 53, the registration roller drive motor 45, and the belt platen drive motor 51 with the arithmetic unit 37 (S1), and the recording medium. It is determined whether or not W can be fed (S2).

  When the sheet feeding is impossible, the control waits in the control start state. When the sheet feeding is possible, the recording medium W is fed from the sheet feeding means 3 to the registration unit 39, and the registration rollers 41 and 43 are connected to the belt platen 9. Driven at a constant speed, the recording medium W is sent out from the registration section 39 to the transport means 11 (S3).

  After confirming that the leading end 19 in the transport direction of the recording medium W has been transported to the position of the leading end detection sensor 47 (S4), the suction means 17 transports the recording medium W in the suction section 15 in the first row in the transport direction. All the suction parts 15 in which the tip 19 in the direction is located are operated (S5).

  Next, it is determined whether or not the leading end portion 19 in the transport direction of the recording medium W has passed through the suction portion 15 in the first row in the transport direction of the suction means 17 (S6). If it has not passed, the control of the suction unit 15 in the first row in the transport direction is continued, and if it has passed, suction in the second row and subsequent rows in the transport direction is performed according to the size in the orthogonal direction of the recording medium W as described above. The unit 15 is controlled (S7).

  Next, it is determined whether or not the feeding of the second recording medium W from the paper feeding means 3 to the registration unit 39 is started while the first recording medium W is passing through the conveying means 11 (S8). . When the feeding of the second recording medium W is started, the second recording medium W is controlled in the same manner as the first recording medium (S2).

  When the feeding of the second recording medium W is not started, it is determined whether or not the rear end portion 65 in the transport direction of the first recording medium W has passed through the transport unit 11 (S9). If so, the suction part of the suction means 17 is stopped (S10), and the control of the suction means 17 is terminated (S11).

  Next, the adsorption of the recording medium W to the belt platen 9 will be described with reference to FIGS.

  As shown in FIGS. 13 and 14, when the recording medium W is attracted to the belt platen 9 by the suction means 17, the apex P where the end in the conveyance direction of the recording medium W intersects with the end in the orthogonal direction is the belt P The platen 9 is disposed on a surface 27 formed between the plurality of holes 25. Thereby, the apex P of the recording medium W is not disposed in the hole 25, and the recording medium W can be reliably attracted to the belt platen 9 by the suction means 17.

  Further, the state in which the apex P of the recording medium W is disposed on the surface 27 formed between the plurality of holes 25 of the belt platen 9 includes the front end 19 in the conveyance direction of the recording medium W and the surface of the belt platen 9. 27 is preferably within 1 mm from the hole 25 (see FIG. 14A). Further, the end portion 19 (end portion 23) in the direction orthogonal to the front end portion 19 in the transport direction of the recording medium W is preferred. The overlap margins 73 and 75 between the belt platen 9 and the surface 27 of the belt platen 9 are more preferably within 1 mm from the hole 25 (see FIG. 14B). By setting the overlap margin in this way, it is possible to reliably prevent the end of the recording medium W from being lifted.

  Control for arranging the apex P of the recording medium W on the surface 27 of the belt platen 9 is performed by the arithmetic unit 37. Here, FIG. 15 is a diagram showing the relationship between the hole 25 of the belt platen 9 and the leading end portion 19 of the recording medium W with respect to time (seconds) and moving distance (mm). Indicates the range of the holes 25, and the surface 27 of the belt platen 9 is shown between the holes 25.

  First, the position of the hole 25 of the belt platen 9 is confirmed by the belt hole detection sensor 53 with the time point when the leading end 19 of the recording medium W has passed the leading edge detection sensor 47 as a base point. The relationship (deviation) with the tip 19 is measured.

  At this time, if the hole 25 of the belt platen 9 and the leading end 19 of the recording medium W are greatly separated when the leading end 19 of the recording medium W reaches the conveying means 11 (suction means 17), The registration roller drive motor 45 is accelerated or decelerated at a stage before the tip 19 is sucked by the suction means 17. Thereby, the conveyance speed of the recording medium W is accelerated or decelerated, and when the leading end 19 of the recording medium W reaches the conveying means 11, the hole 25 of the belt platen 9 and the leading end 19 of the recording medium W are brought close to each other. .

  Then, the apex P of the recording medium W can be arranged on the surface 27 of the belt platen 9 by operating the suction means 17 in a state where the hole 25 of the belt platen 9 and the tip 19 of the recording medium W are synchronized. it can. In FIG. 15, the leading end 19 of the recording medium W is in a state of being disposed on the hole 25 of the belt platen 9 (the state of FIG. 13), but the acceleration / deceleration of the registration roller drive motor 45 is adjusted. As a result, the overlap margin 73 between the front end portion 19 in the conveyance direction of the recording medium W and the surface 27 of the belt platen 9 can be brought into a state within 1 mm from the hole 25 (the states shown in FIGS. 14A and 14B). .

  Here, the operation of attracting the recording medium W to the belt platen 9 will be described with reference to the flowchart of FIG.

  First, the suction unit 59 is started by controlling the suction fan 59, the leading end detection sensor 47, the belt hole detection sensor 53, the registration roller drive motor 45, and the belt platen drive motor 51 with the arithmetic unit 37 (S1), and the recording medium. It is determined whether or not W can be fed (S2).

  When the sheet feeding is impossible, the control waits in the control start state. When the sheet feeding is possible, the recording medium W is fed from the sheet feeding means 3 to the registration unit 39, and the registration rollers 41 and 43 are connected to the belt platen 9. Driven at a constant speed, the recording medium W is sent out from the registration section 39 to the transport means 11 (S3).

  It is confirmed that the leading end 19 in the transport direction of the recording medium W has been transported to the position of the leading end detection sensor 47 (S4). At this time, the position of the hole 25 in the belt platen 9 and the recording medium W are detected by the belt hole detection sensor 53. Is compared with the position of the tip 19 (S21).

  Next, it is determined whether or not the leading end 19 of the recording medium W and the hole 25 of the belt platen 9 are synchronized (S22). In the case of synchronization, the registration roller drive motor 45 is directly driven at the same speed as the belt platen drive motor 51 (the rotation speed at which the conveyance speed of the recording medium W is constant) to complete the feeding of the recording medium W. (S26).

  If not synchronized, the distance between the hole 25 of the belt platen 9 and the leading end 19 of the recording medium W when the leading end 19 of the recording medium W reaches the conveying means 11 in this state is calculated. (S23). The registration roller drive motor 45 is accelerated or decelerated in accordance with this distance, and the conveyance speed of the recording medium W is accelerated or decelerated (S24).

  When the leading end 19 of the recording medium W reaches the conveying means 11, the registration roller driving motor 45 is moved to the belt when the hole 25 of the belt platen 9 and the leading end 19 of the recording medium W come close to each other. The platen drive motor 51 is driven at a constant speed (the number of rotations at which the conveyance speed of the recording medium W is constant) (S25), and the feeding of the recording medium W is completed (S26).

  When the tip 19 of the recording medium W and the hole 25 of the belt platen 9 are not synchronized, the acceleration / deceleration of the registration roller drive motor 45 is adjusted. However, the present invention is not limited to this. The acceleration / deceleration of the belt platen drive motor 51 may be adjusted according to the conveyance speed of W.

  In such an image forming apparatus 1, the suction unit 17 that varies the positions of the plurality of suction units 15 that suck the recording medium W against the belt platen 9 in accordance with the size in the orthogonal direction orthogonal to the conveyance direction of the recording medium W. Therefore, the position of the suction portion 15 can be made different with respect to the recording medium W having a different size in the orthogonal direction, and the suction force of the suction means 17 is not wasted.

Accordingly, the recording medium W can be efficiently sucked with respect to the belt platen 9. Also, since the position of the suction portion 15 is varied according to the size of the recording medium W in the orthogonal direction, any size of recording can be performed. The lift of the end portion of the recording medium W can be prevented with respect to the medium W, and the contact between the recording medium W and each inkjet head of the printing unit 13 can be prevented.

  Furthermore, since the suction part 15 of the suction means 17 is provided in at least three or more rows in the orthogonal direction and in at least two rows or more in the transport direction, the more sections of the suction means 17 are provided, the more Therefore, the image forming apparatus 1 can be made more efficient.

  In addition, when the suction unit 17 has the leading end 19 in the transport direction of the recording medium W positioned at the suction portion 15 in the first row from the upstream in the transport direction, all of the orthogonal directions in which the leading end 19 in the transport direction of the recording medium W is located. Therefore, when the suction of the recording medium W is started, the end 19 in the conveyance direction of the recording medium W and the both ends 21 and 23 in the orthogonal direction can be reliably attracted to the belt platen 9.

  Further, when the suction means 17 is positioned at the suction section 15 in the second and subsequent rows from the upstream side in the transport direction of the recording medium W, the orthogonal positions at which both ends 21 and 23 in the orthogonal direction of the recording medium W are positioned. Since the direction suction section 15 is operated, the belt platen 9 reliably prevents the opposite ends 21 and 23 of the recording medium W from being lifted when the recording medium W is conveyed, while the recording medium W is attracted when the recording medium W is conveyed. It is possible to save energy by putting the suction unit 15 unnecessary for the operation into a stopped state.

  Further, when the recording medium W is sucked by the suction means 17, the apex P of the recording medium W is arranged on the surface 27 formed between the plurality of holes 25 of the belt platen 9. Can be prevented from entering the hole 25, and the recording medium W can be reliably adsorbed to the belt platen 9 by the suction means 17.

  Further, since the total surface area of the holes 29 of the lid member 31 is set larger than the total surface area of the holes 25 of the belt platen 9, the suction force from the suction portion 15 of the suction means 17 exerted on the belt platen 9 is reduced. As a result, the recording medium W can be efficiently sucked onto the belt platen 9.

  In the suction unit, when the leading end of the recording medium in the transport direction is positioned at the suction section in the first row from the upstream in the transport direction, all the suction sections in the orthogonal direction where the leading end of the recording medium in the transport direction is located are operated. However, the suction force of the suction part located between the suction parts is at least smaller than the suction force of the suction part where both ends of the recording medium in the orthogonal direction are located in the suction part of the first row from the upstream in the transport direction. The suction force may be reduced to such an extent that can be sucked.

1 is a schematic diagram illustrating an image forming apparatus according to an embodiment. It is a top view of a belt platen. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. 2 is a block diagram illustrating a control system of the image forming apparatus. FIG. It is a top view of a belt platen, and is a figure which shows a suction means. It is a figure which shows the modification of a storage body. It is a principal part expanded sectional view of a suction means. It is a top view of a lid member. It is a figure which shows the modification of the hole of a cover member. It is a figure which shows operation | movement of a suction means. It is a flowchart which shows operation | movement of a suction means. FIG. 4 is a diagram illustrating an adsorption state of a recording medium with respect to a belt platen. FIG. 7 is a diagram illustrating another example of the state of adsorption of the recording medium to the belt platen. It is a figure which shows control of the front-end | tip part of a recording medium, and the hole of a belt platen. 6 is a flowchart illustrating an operation of attracting a recording medium to a belt platen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 3 ... Paper feeding means 5, 7 ... Roller (rotating shaft)
DESCRIPTION OF SYMBOLS 9 ... Belt platen 11 ... Conveyance means 13 ... Printing means 15 ... Suction part 17 ... Suction means 19 ... End part 21 in conveyance direction ... Both ends part in orthogonal direction 25 ... Hole 27 ... Surface 29 ... Hole part 31 ... Cover member P ... apex W ... recording medium

Claims (6)

Paper feeding means for feeding the stored recording medium;
A transport unit provided with an annular belt platen disposed downstream of the sheet feeding unit in the transport direction of the recording medium and having both ends fixed to a rotation shaft;
Printing means provided on the conveying means for printing on the recording medium;
A suction unit that is provided in the transport unit and varies the positions of a plurality of suction units that suck the recording medium with respect to the belt platen in accordance with a size in a direction orthogonal to the transport direction of the recording medium;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the suction unit includes a plurality of the suction units in at least three rows with respect to the orthogonal direction. The image forming apparatus according to claim 2,
The image forming apparatus according to claim 1, wherein the suction unit includes a plurality of the suction units in at least two rows in the transport direction. The image forming apparatus according to claim 3, wherein
The suction means includes all the orthogonal directions in which the leading ends of the recording medium in the transport direction are located when the leading ends of the recording medium in the transport direction are located in the suction section in the first row from the upstream in the transport direction. The orthogonal position where both ends of the recording medium in the orthogonal direction are located when the suction section is activated and the leading end in the conveyance direction of the recording medium is positioned in the suction section in the second and subsequent rows from the upstream in the conveyance direction An image forming apparatus, wherein the suction part in the direction is operated. The image forming apparatus according to any one of claims 1 to 4, wherein
The belt platen has a plurality of holes, and when the recording medium is sucked by the suction means, the apex at which the end in the transport direction and the end in the orthogonal direction of the recording medium intersect is the plurality of holes. An image forming apparatus, wherein the image forming apparatus is disposed on a surface formed therebetween. The image forming apparatus according to any one of claims 1 to 5,
A lid member having a plurality of holes is disposed between the belt platen and the plurality of suction portions, the belt platen has a plurality of holes, and a total surface area of the holes of the lid member. Is larger than the total surface area of the holes of the belt platen.

Images