JP4998425B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that ejects ink onto a recording medium.

  In Patent Document 1, four ink jet recording heads, a belt platen that transports recording paper along the transport direction to positions facing the four ink jet recording heads, and upstream and downstream of the four ink jet recording heads are arranged. An ink jet recording apparatus including two paper sensors is described. In this ink jet recording apparatus, after the upstream sheet sensor detects the recording sheet, if the downstream sheet sensor does not detect the sheet after a certain time, it is determined that a jam (paper jam) has occurred in the recording sheet, and the jam processing Is done.

International Publication No. WO2006 / 054665 Pamphlet

  In the ink jet recording apparatus described in Patent Document 1, a paper sensor is disposed downstream of the ink jet recording head. Ink mist generated when ink is ejected from the ink jet recording head is caused to flow mainly downstream due to the air flow accompanying the conveyance of the recording paper, so that a large amount of ink mist adheres to the downstream paper sensor. When ink mist adheres to the paper sensor in this way, the detection accuracy of the recording paper is lowered, and it is impossible to determine whether or not a jam has occurred on the recording paper. Therefore, the recording medium is jammed, and the recording paper is not conveyed to the position facing the ink jet recording head, but the ink is ejected from the ink jet recording head, and the belt platen (conveying belt) which is a conveying mechanism is removed. The problem of fouling arises.

  Accordingly, an object of the present invention is to provide an ink jet recording apparatus in which ink mist hardly adheres to a sensor.

The ink jet recording apparatus of the present invention, the ink jet head discharge surface for discharging a Lee ink is formed, which can length along the conveying path is conveyed along the conveying path different from the recording medium from each other conveyance And a mechanism for controlling the transport mechanism so that the recording medium is transported to a position facing the ejection surface, and for controlling the inkjet head so that ink is ejected to the recording medium based on print data. Means, a first sensor disposed upstream of the inkjet head along the transport path and detecting a front end of the recording medium transported by the transport mechanism, and the first sensor along the transport path The front end of the recording medium disposed upstream of the recording medium and conveyed by the conveyance mechanism is located downstream of the upstream side surface of the inkjet head. And a second sensor which detects the trailing edge of the recording medium when. The control means is configured to detect the recording medium when the second sensor does not detect the trailing edge of the recording medium after the first sensor detects the leading edge of the recording medium and until a predetermined time elapses. The inkjet head is controlled so that ink ejection is stopped , and after a predetermined time has elapsed since the first sensor detects the front end of the recording medium, ink ejection is started to the recording medium. To control .

According to this, since the first and second sensors are arranged upstream of the ink jet head and the second sensor is arranged at a position relatively distant from the ink jet head, the ink mainly flows downstream along the transport path. Mist is less likely to adhere to both sensors. For this reason, it is possible to accurately detect whether or not a jam has occurred in the recording medium. As a result, it is possible to prevent the occurrence of a jam and the ejection of ink even though the recording medium does not exist at the position facing the ejection surface, and it is possible to suppress the conveyance mechanism from being soiled by the ink. it can. In addition, it is possible to improve the ink ejection accuracy with respect to the recording medium.

  In the present invention, the inkjet head includes a plurality of the inkjet heads arranged in one direction along the transport path, and is disposed upstream of the inkjet head disposed upstream in the one direction, and A third sensor is further provided for detecting the rear end of the recording medium when the front end of the recording medium conveyed by the conveying mechanism is between two adjacent ink jet heads. And when the third sensor does not detect the trailing edge of the recording medium between the time when the second sensor detects the trailing edge of the recording medium and a predetermined time elapses. It is preferable to control the ink jet head so as to stop the ink ejection with respect to the ink jet head. Thereby, since the detection interval of the recording medium by the first, second and third sensors is shortened, it is possible to detect whether or not a jam has occurred in the recording medium more quickly.

  Further, at this time, with respect to the one direction, the front end of the recording medium disposed upstream of the inkjet head disposed upstream and conveyed by the conveyance mechanism is located downstream of the two inkjet heads. A fourth sensor is further provided for detecting the trailing edge of the recording medium when it is downstream of the upstream side surface of the disposed inkjet head. And when the fourth sensor does not detect the trailing edge of the recording medium between the time when the third sensor detects the trailing edge of the recording medium and a predetermined time elapses. The ink jet head may be controlled so as to stop the ink ejection with respect to the ink jet head. This makes it possible to detect in a wide range whether or not a jam has occurred in the recording medium.

  Further, at this time, with respect to the one direction, the inkjet head is arranged upstream from the inkjet head arranged at the most upstream, and the front end of the recording medium conveyed by the conveyance mechanism is from the inkjet head arranged at the most downstream side. Is further provided with a fifth sensor for detecting the trailing edge of the recording medium when it is downstream. And when the fifth sensor does not detect the trailing edge of the recording medium after the fourth sensor detects the trailing edge of the recording medium and before a predetermined time elapses, The ink jet head may be controlled so as to stop the ink ejection with respect to the ink jet head. This makes it possible to detect whether or not a jam has occurred in the recording medium before the front end of the recording medium passes through the most downstream ink jet head.

Also, in the present invention, the second sensor is preferably a length along the transport path are plural arranged according to different recording medium. As a result, it is possible to detect whether or not a jam has occurred in the recording medium even when recording media having different lengths along the conveyance path are conveyed.

  In the present invention, it is preferable to further include a moving mechanism that moves the first sensor and the second sensor according to recording media having different lengths along the transport path. This eliminates the need to provide a plurality of first and second sensors even when recording media having different lengths along the transport path are transported, thereby suppressing an increase in manufacturing cost of the device itself and increasing the size of the device itself. Can be suppressed.

According to the ink jet recording apparatus of the present invention, the first and second sensors are disposed upstream of the ink jet head, and the second sensor is disposed at a position relatively distant from the ink jet head. Thus, the ink mist flowing downstream is less likely to adhere to both sensors. For this reason, it is possible to accurately detect whether or not a jam has occurred in the recording medium. As a result, it is possible to prevent the occurrence of a jam and the ejection of ink even though the recording medium does not exist at the position facing the ejection surface, and it is possible to suppress the conveyance mechanism from being soiled by the ink. it can. In addition, it is possible to improve the ink ejection accuracy with respect to the recording medium.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an appearance of the ink jet printer according to the first embodiment of the present invention. FIG. 2 is a schematic side view showing the internal structure of the ink jet printer shown in FIG. FIG. 3 is a schematic diagram showing the separation distance of the sensor with respect to the inkjet head. In FIG. 3, the ink jet head and the sensor are drawn in a straight line for easy understanding of the separation distance of the sensor.

  As shown in FIG. 1, the inkjet printer 1 has a rectangular parallelepiped housing 1 a, and two openings 3 a and 3 b are sequentially provided from the top (front side on the left side in FIG. 1) from the top. Is formed. The opening 3a is provided with a door 4 that can be opened and closed with the horizontal axis at the lower end as a fulcrum. The opening 3a and the door 4 are disposed to face the belt conveyance device 50 in the depth direction of the housing 1a (the direction perpendicular to the paper surface of FIG. 2 and perpendicular to the conveyance direction A).

  As shown in FIG. 2, the ink jet printer 1 is a color ink jet printer having four ink jet heads 2 that respectively eject magenta, cyan, yellow, and black inks. The printer 1 is provided with a paper feeding device 10 at the lower side in FIG. 2 and a paper discharge unit 15 at the upper side in FIG. 2, and a belt conveying device 50 is provided therebetween. In the printer 1, a conveyance path of the paper P from the paper feeding device 10 to the paper discharge unit 15 through the belt conveyance device 50 is formed. Further, the printer 1 includes a control unit 100 that controls these operations.

  As shown in FIG. 2, the sheet feeding device 10 (part of the transport mechanism) includes a sheet feeding cassette 11 that can store a plurality of stacked sheets P, and a sheet feeding roller 12 that feeds the sheets P from the sheet feeding cassette 11. And a paper feed motor 13 (see FIG. 4) for rotating the paper feed roller 12. The paper feed cassette 11 is detachably disposed in the direction perpendicular to the paper surface of FIG. 2, and is disposed at a position overlapping the belt conveyance device 50 in the vertical direction in FIG. 2 when mounted on the housing 1a. Further, the paper feed cassette 11 is configured to be able to store paper P (for example, A4 size paper P1 and B5 size paper P2) having different lengths along the transport path.

  The paper feed roller 12 feeds the paper P from the paper feed cassette 11 by rotating and contacting the paper P positioned at the uppermost position. The paper feed motor 13 is controlled by the control unit 100. On the left end side in FIG. 1 of the paper feed cassette 11, a transport guide 17 (part of the transport path) that extends while curving from the paper feed cassette 11 toward the belt transport device 50 is provided.

  In this configuration, the paper feed roller 12 rotates in the clockwise direction in FIG. 2 under the control of the control unit 100, so that the paper P in contact with the paper feed roller 12 is sent out to the belt conveyance device 50 through the conveyance guide 17. It is.

  The belt conveyance device 50 (a part of the conveyance mechanism) includes two belt rollers 51 and 52, a conveyance belt 53, and a platen 57, and conveys the paper P in the conveyance direction A. The conveyor belt 53 is an endless belt that is wound around the rollers 51 and 52. The platen 57 is disposed in a region surrounded by the conveyance belt 53. The platen 57 supports the conveyor belt 53 at a position facing the inkjet head 2 so that the conveyor belt 53 does not bend downward. The belt roller 52 is a driving roller, and rotates in the clockwise direction in FIG. 2 when a driving force is applied to the shaft of the belt roller 52 from the transport motor 59 (see FIG. 4). The belt roller 51 is a driven roller, and rotates in the clockwise direction in FIG. 2 when the conveyor belt 53 travels as the belt roller 52 rotates.

  The conveyance surface 54 that is the outer peripheral surface of the conveyance belt 53 is subjected to silicone treatment and has adhesiveness. A nip roller 48 is disposed at a position facing the belt roller 51. The nip roller 48 presses the sheet P sent out from the sheet feeding device 10 against the conveyance surface 54. The paper P pressed against the transport surface 54 is transported in the transport direction A while being held on the transport surface 54 by the adhesive force. As described above, a part of the conveyance path is also formed between the belt conveyance device 50 and the inkjet head 2.

  A peeling member 9 is provided immediately downstream in the conveyance direction A of the belt conveyance device 50. The peeling member 9 peels off the paper P from the conveyance surface 54 by the leading end of the peeling member 9 entering between the paper P and the conveyance belt 53.

  As shown in FIGS. 2 and 3, the printer 1 is provided with 18 sensors 80 to 97 that detect the paper P along the conveyance path. These 18 sensors 80 to 97 are located upstream of the inkjet head 2 arranged first in the conveyance direction A (the most upstream arrangement), and the trailing edge of the paper P passing through the guide 17 is detected. It is arranged so that it can be detected. The 18 sensors 80 to 97 transmit detection signals to the control unit 100 when the trailing edge of the paper P is detected. Of the eighteen sensors 80 to 97, nine sensors 80 to 88 detect the rear end of the A4 size paper P1 sent out from the paper cassette 11, and the nine sensors 89 to 97 are B5 size paper. The rear end of P2 is detected.

  Specifically, as shown in FIG. 3A, the sensor 80 is located when the front end of the paper P1 is upstream of the first disposed inkjet head 2 and in the vicinity of the inkjet head 2. The rear end of the paper P1 is disposed at a position where it can be detected. The sensor 81 can detect the rear end of the paper P1 when the front end of the paper P1 is downstream of the upstream side of the ink jet head 2 arranged first and is opposed to the center of the ejection surface 2a. It is arranged in the position. The sensor 82 is disposed at a position where the rear end of the sheet P1 can be detected when the front end of the sheet P1 is in the middle of the two inkjet heads 2 disposed first and second. The sensor 83 is disposed at a position where the rear end of the sheet P1 can be detected when the front end of the sheet P1 is at a position facing the center of the ejection surface 2a of the inkjet head 2 disposed second. Similarly to the sensors 81 and 83, the sensors 85 and 87 are arranged such that the rear end of the paper P1 when the front end of the paper P1 is at a position facing the center of the ejection surface 2a of the third and fourth inkjet heads 2. Are arranged at positions where they can be detected. Similarly to the sensor 82, the sensors 84 and 86 are arranged to follow the paper P1 when the front end of the paper P1 is in the middle of the second and third ink jet heads 2 and in the middle of the third and fourth ink jet heads 2, respectively. The ends are arranged at positions where they can be detected. The sensor 88 is located downstream of the inkjet head 2 in which the front end of the paper P1 is arranged fourth (most downstream) and in the vicinity of the inkjet head 2, and the sensor P1 It is arranged at a position where the rear end can be detected. In addition, the sensors 80-88 are arrange | positioned at equal intervals along the conveyance path | route.

  As shown in FIG. 3B, when the front end of the paper P2 is upstream of the ink jet head 2 arranged first and in the vicinity of the ink jet head 2, as shown in FIG. It is arranged at a position where the end can be detected. The seven sensors 90 to 96 are different when the corresponding paper P is different, and the front end of the paper P2 is at a position facing the center of the ejection surface 2a of the first to fourth ink jet heads 2 as in the sensors 81 to 87. And when it is in the middle between the respective heads of the first to fourth inkjet heads 2, it is arranged at a position where the rear end of the paper P2 can be detected. Similarly to the sensor 88, the sensor 97 also has a rear end of the paper P2 when the front end of the paper P2 is downstream of the fourth inkjet head 2 and in the vicinity of the ink jet head 2. It is arranged at a position where can be detected. The sensors 89 to 97 are arranged at equal intervals along the transport path.

  As shown in FIG. 2, there are four feed rollers 21a, 21b, 22a, 22b (part of the transport mechanism), the feed rollers 21a, 21b, and the feed roller between the belt transport device 50 and the paper discharge unit 15. A transport guide 18 (a part of the transport path) disposed between 22a and 22b is disposed. The feed rollers 21b and 22b are rotationally driven by feed motors 23 and 24 (see FIG. 4) controlled by the control unit 100. In this configuration, the feed motors 23 and 24 are driven so that the feed rollers 21b and 22b rotate under the control of the control unit 100, and the paper P discharged from the belt conveying device 50 is held between the feed rollers 21a and 21b. 2 is passed through the transport guide 18 and sent upward in FIG. 2, and then sent to the paper discharge unit 15 while being held between the feed rollers 22a and 22b. The feed rollers 21a and 22a are driven rollers and rotate as the paper is conveyed.

  The four inkjet heads 2 are provided side by side along the transport direction A as shown in FIG. That is, the ink jet printer 1 is a line printer. The inkjet head 2 has an elongated rectangular parallelepiped shape whose longitudinal direction extends in a direction orthogonal to the transport direction A. The inkjet head 2 has a laminate (both not shown) in which a flow path unit in which an ink flow path including a pressure chamber is formed and an actuator that applies pressure to the ink in the pressure chamber are bonded together. The bottom surface is an ejection surface 2a on which a plurality of ejection ports (not shown) for ejecting ink are formed. Then, when the paper P transported by the belt transport device 50 passes just below the four inkjet heads 2, the inks of the respective colors are sequentially ejected from the ejection ports toward the upper surface of the paper P. Thereby, a desired color image is formed on the upper surface of the paper P, that is, the printing surface.

  Next, the control unit 100 will be described. The control unit 100 is configured by, for example, a general-purpose personal computer. Such a computer stores hardware such as a CPU, ROM, RAM, and hard disk, and various software including a program for controlling the operation of the printer 1 is stored in the hard disk. Then, by combining these hardware and software, later-described units 101 to 103 (see FIG. 4) are constructed.

  4 is a block diagram showing a schematic configuration of the control unit 100 shown in FIG. The control unit 100 includes a print control unit 101, a conveyance control unit 102, and a jam determination unit 103. The print control unit 101 controls each inkjet head 2 to eject ink onto the paper P based on print data transferred from a host computer (not shown). At this time, the print control unit 101 detects that the sensor 80 detects the trailing edge of the paper P1 conveyed by the belt conveying device 50 or the sensor 89 detects the trailing edge of the paper P2 after a predetermined time has elapsed. Each inkjet head 2 is controlled so that ink is ejected onto the paper P. The predetermined time here refers to the distance along the transport path from the front end of the paper P when the sensors 80 and 89 detect the rear end to the most upstream discharge port for discharging the ink of the first inkjet head 2. The time divided by the conveyance speed of the paper P.

  Note that the print data includes paper data indicating the paper size (A4, B5, etc.) selected by the user. Based on this paper data, the print control unit 101 uses the two sensors 80 and 89. It is determined whether the detection signal of the paper P is valid. That is, when the A4 size paper P1 is conveyed, only the detection signal from the sensor 80 is determined to be valid, and when the B5 size paper P2 is conveyed, only the detection signal from the sensor 89 is determined to be valid. Then, the above-described ink discharge control is performed.

  The transport control unit 102 controls the paper feed motor 13, the transport motor 59, and the feed motors 23 and 24 so as to transport the paper P from the paper supply device 10 to the paper discharge unit 15.

  The jam determination unit 103 determines whether the detection signals of the paper P from the 18 sensors 80 to 97 are valid according to the paper data. That is, when the A4 size paper P1 is conveyed, it is determined that the detection signals from the sensors 80 to 88 are valid, and when the B5 size paper P2 is conveyed, the detection signals from the sensors 89 to 97 are valid. Is determined. Then, it is determined that a jam has occurred on the paper P only when the detection intervals in these effective detection signals respectively exceed a predetermined time. The predetermined time referred to here is obtained by dividing the distance between the sensors by the conveyance speed of the paper P in the two sensor sets (the sensor set of the sensors 80 to 88 and the sensor set of the sensors 89 to 97) according to the paper size. It was time. In addition, since the nine sensors constituting the sensor set are arranged at equal intervals along the conveyance path, the predetermined time between the sensors is the same.

  Specifically, when the A4 size paper P1 is transported, the jam determination unit 103 first detects a rear end of the paper P1 by the sensor (first sensor) 80 (predetermined time of the sensors 80 and 81). Jam on the paper P1 when the sensor (second sensor) 81 does not detect the trailing edge of the paper P1 until the separation distance along the transport path is divided by the transport speed of the paper P1. Is determined to have occurred. Further, the jam determination unit 103 detects when the sensor (third sensor) 82 does not detect the trailing edge of the paper P1 after the sensor 81 detects the trailing edge of the paper P1 until a predetermined time elapses. It is determined that a jam has occurred on the paper P1. Further, the jam determination unit 103 detects when the sensor (fourth sensor) 83 does not detect the trailing edge of the paper P1 after the sensor 82 detects the trailing edge of the paper P1 until a predetermined time elapses. It is determined that a jam has occurred on the paper P1. The determination unit 103 determines that a jam has occurred in the paper P1 only when the detection intervals at which the trailing edge of the paper P1 is detected exceed the predetermined time in the order of the sensors 84 to 88 as the paper is conveyed. .

  On the other hand, when the B5 size paper P2 is transported, the jam determination unit 103 detects the paper P2 in the order of the sensors 89 to 97 along with the paper transport, as in the case of the paper P1. Only when the predetermined time is exceeded, it is determined that a jam has occurred on the paper P2. Note that the predetermined time here is the same as the above-mentioned predetermined time because the distance between the sensors in each group is the same. When the jam determination unit 103 determines that a jam has occurred as described above, the jam determination unit 103 controls the print control unit 101 and the conveyance control unit 102 to stop the ink ejection from each inkjet head 2 and the paper. The conveyance of P is stopped. In addition, when the detection interval from the sensor corresponding to the conveyed paper P is within a predetermined time and the jam determination unit 103 does not determine that a jam has occurred, the paper P receives ink when facing the inkjet head 2. An image is formed by ejection, and is ejected to the paper ejection unit 15.

  As described above, according to the inkjet printer 1 of the present embodiment, the sensors (first sensors) 80 and 89 and the sensors (second sensors) 81 and 90 are upstream of the inkjet head 2 which is the most upstream, and the inkjet head. 2, the ink mist that flows downstream along the transport path mainly passes to the sensors 80, 81, 89, 90. It becomes difficult to adhere. For this reason, it is possible to accurately detect whether or not a jam has occurred in the paper P. As a result, it is possible to prevent the ink from being ejected onto the paper P even when the jam occurs and the paper P does not exist at the position facing the ejection surface, and the belt conveyance device 50 is contaminated by the ink. Can be suppressed. In addition, since all the 18 sensors 80 to 97 are arranged upstream of the first inkjet head 2, it is difficult for the ink mist to adhere to any of the sensors 80 to 97.

  In addition, sensors (third sensors) 82 and 91 are arranged upstream of the first inkjet head 2, and a predetermined time has elapsed since the jam determination unit 103 detected the trailing edge of the paper P by the sensors 81 and 90. In the meantime, when the sensors 82 and 91 do not detect the trailing edge of the paper P, the print control unit 101 is controlled so as to stop ink ejection on the paper P. Thereby, since the detection interval of the paper P in the sensors 80 and 89, the sensors 81 and 90, and the sensors 82 and 91 is shortened, it becomes possible to quickly determine whether or not the paper P is jammed.

  Further, sensors (fourth sensors) 83 and 92 are arranged upstream of the first inkjet head 2, and a predetermined time has elapsed since the jam determination unit 103 detected the trailing edge of the paper P by the sensors 82 and 91. In the meantime, when the sensors 83 and 92 do not detect the trailing edge of the paper P, the print control unit 101 is controlled so as to stop ink ejection on the paper P. Thereby, it is possible to detect in a wide range whether or not a jam has occurred in the paper P.

  Further, sensors (fifth sensors) 88 and 97 are arranged upstream of the first inkjet head 2, and a predetermined time has elapsed since the jam determination unit 103 detected the trailing edge of the paper P by the sensors 87 and 96. In the meantime, when the sensors 88 and 97 do not detect the trailing edge of the paper P, the print controller 101 is controlled so as to stop ink ejection on the paper P. Thereby, it is possible to determine whether or not a jam has occurred in the paper P before the front end of the paper P passes through the inkjet head 2 located on the most downstream side.

  In addition, since eighteen sensors 80 to 97 are arranged according to the paper size (paper sizes having different lengths along the conveyance path), the paper P is jammed even when different sizes of paper are conveyed. It is possible to determine whether or not there is.

  Subsequently, a second embodiment of the present invention will be described. FIG. 5 is a schematic side view showing the internal structure of the inkjet printer according to the second embodiment of the present invention. In addition, about the thing similar to 1st Embodiment, it shows with the same code | symbol and abbreviate | omits description. The ink jet printer 201 according to the present embodiment includes a sensor 294 disposed upstream of the ink jet head 2 disposed first and in the vicinity of the ink jet head 2 instead of the sensors 80 and 89 according to the first embodiment. Have. The sensor 294 is disposed at a position where the front edge of the paper P can be detected when the sensors 80 and 89 detect the rear edge of the paper P.

  The printer 201 also has a control unit 200 that is substantially the same as the control unit 100 of the first embodiment. As shown in FIG. 5, the control unit 200 includes a print control unit 211, a conveyance control unit 212, and a jam determination unit 213.

  The print control unit 211 is substantially the same as the print control unit 101 of the first embodiment, and after a predetermined time has elapsed since the sensor 294 detected the front end of the paper P conveyed by the belt conveyance device 50, the paper P Each ink jet head 2 is controlled so as to eject ink. The predetermined time here is a time obtained by dividing the distance from the sensor 294 along the transport path to the most upstream ejection port that ejects the ink of the first inkjet head 2 by the transport speed of the paper P. As described above, the sensor 294 is arranged upstream of the first inkjet head 2 and in the vicinity of the inkjet head 2, and the above-described control is performed by the print control unit 211, thereby improving the ink ejection accuracy with respect to the paper P. It becomes possible. The conveyance control unit 212 performs the same control as the conveyance control unit 102 of the first embodiment.

  The jam determination unit 213 determines whether the detection signal of the paper P from the 17 sensors 81 to 88, 90 to 97, and 294 is valid according to the paper data. That is, when the A4 size paper P1 is transported, the detection signals from the sensors 81 to 88, 294 are determined to be valid, and when the B5 size paper P2 is transported, the sensors 90 to 97, 294 It is determined that the detection signal is valid. Then, it is determined that a jam has occurred on the paper P only when the detection intervals in these effective detection signals respectively exceed a predetermined time.

  Specifically, when the A4 size paper P1 is conveyed, the jam determination unit 213 determines whether the sensor (first sensor) 294 detects the front edge of the paper P1 for a predetermined time (when the sensor 294 detects the front edge). When the sensor 81 does not detect the trailing edge of the sheet P1 until the distance from the trailing edge of the sheet P1 to the sensor 81 along the conveying path is divided by the conveying speed of the sheet P1). It is determined that a jam has occurred on the paper P1. On the other hand, when the B5 size paper P2 is conveyed, the jam determination unit 213 conveys from the rear end of the paper P2 when the sensor 294 detects the front edge of the paper P1 for a predetermined time (the sensor 294 detects the front edge). Jam occurs on the paper P2 when the sensor 90 does not detect the trailing edge of the paper P2 until the time (distance obtained by dividing the distance to the sensor 90 along the path by the conveyance speed of the paper P2) elapses. Is determined. Other than these, the jam determination unit 213 performs the same control as the jam determination unit 103 of the first embodiment, and when the jam determination unit 213 determines that a jam has occurred, the print control unit 211 and the conveyance control unit 212. Are controlled to stop the ink ejection from each inkjet head 2 and to stop the conveyance of the paper P.

  As described above, according to the ink jet printer 201 of the present embodiment, the sensor 294 and the sensors 81 and 90 are disposed upstream of the first ink jet head 2 and the sensors 81 and 90 are relatively separated from the ink jet head. Since it is arranged at the position, it is possible to obtain the same effect as in the first embodiment. Also, since the sixty-one 81 to 88 and 90 to 97 are arranged in accordance with the paper size, it is possible to determine whether or not a jam has occurred in the paper P even when different sizes of paper are conveyed. It becomes possible.

  Subsequently, a third embodiment of the present invention will be described. FIG. 6 is a schematic side view showing the internal structure of the ink jet printer according to the third embodiment of the present invention. FIG. 7 is a schematic perspective view of the moving mechanism shown in FIG. FIG. 8 is a block diagram showing a schematic configuration of the control unit 300 shown in FIG. In addition, about the thing similar to 2nd Embodiment, it shows with the same code | symbol and abbreviate | omits description.

  As shown in FIG. 6, the ink jet printer 301 according to the present embodiment includes a moving mechanism 350 that moves the sensors 81 to 88 instead of the sensors 90 to 97 according to the second embodiment. This is almost the same as the embodiment.

  As shown in FIG. 7, the moving mechanism 350 includes a plate-like member 351 extending along the conveyance path, eight support members 352 fixed to the plate-like member 351 and supporting the sensors 81 to 88, and a rotation shaft. And a drive motor (not shown) having a pinion fixed thereto. Note that the plate-like member 351 has flexibility and bends along with the movement along the conveyance path.

  A rack 351 a that meshes with the pinion is formed on the lower surface of the plate-like member 351. Four protrusions 351b protruding in the width direction from the side surfaces are formed at both ends in the longitudinal direction of the plate-like member 351. These four protrusions 351b are slidably fitted in a guide groove (not shown) extending along the conveyance path in the printer 301. In this configuration, the plate-like member 351 moves along the transport path by driving the drive motor under the control of the control unit 300. Normally, the sensors 81 to 88 are arranged at a position where the trailing edge is detected when the A4 size paper P1 is transported, and the sensor 81 is used by the moving mechanism 350 only when the B5 size paper P2 is transported. ˜88 are moved to the position where the trailing edge of the B5 size paper P2 is detected, that is, the positions of the sensors 90 to 97 in the second embodiment.

  As illustrated in FIG. 8, the control unit 300 includes a print control unit 311, a conveyance control unit 312, a jam determination unit 313, and a movement mechanism control unit 314. The print control unit 311 and the conveyance control unit 312 perform the same control as the print control unit 211 and the conveyance control unit 212 of the second embodiment. The movement mechanism control unit 314 moves the sensors 81 to 88 to a position corresponding to either the A4 size paper P1 or the B5 size paper P2 according to the paper data included in the print data. To control.

  The jam determination unit 313 determines that a jam has occurred on the paper P only when the detection intervals in the detection signals from the nine sensors 81 to 88, 294 exceed a predetermined time. That is, the jam determination unit 313 detects that the paper P is jammed in the order of the sensor 294 and the sensors 81 to 88 as the paper P is conveyed only when the detection interval of the paper P exceeds a predetermined time. Is determined. When the jam determination unit 313 determines that a jam has occurred, the jam determination unit 313 controls the print control unit 311 and the conveyance control unit 312 to stop ink ejection from each inkjet head 2 and to convey the paper P. Stop. The predetermined time here is the same as each predetermined time in the second embodiment.

  As described above, also in the ink jet printer 301 of the present embodiment, the same effects as those of the second embodiment can be obtained. Further, since the moving mechanism 350 is provided, the sensors 81 to 88 can be moved according to the paper size. This eliminates the need to provide more sensors upstream of the inkjet head 2 even when different sizes of paper P are transported, thereby suppressing an increase in manufacturing cost of the device itself and an increase in size of the device itself. It becomes possible. This effect is more effective as the number of paper sizes to be conveyed increases.

  In addition, you may employ | adopt the moving mechanism which moves the sensor in this embodiment in 1st Embodiment. That is, without providing the sensor 89, the sensor 80 may be supported by the moving mechanism, and the sensor 80 may be moved according to the paper size. Even in this case, the same effect as that of the third embodiment can be obtained.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, the ink jet printer 1 according to the first embodiment may not include the sensors 82 to 97 other than the sensors 80 and 81. The ink jet printer 201 according to the second embodiment may not include the sensors 82 to 88 and 90 to 97 other than the sensors 81 and 294. The ink jet printer 301 according to the third embodiment may not include the sensors 82 to 88 other than the sensors 81 and 294. Even in these cases, it is possible to accurately detect a jam that occurs between the sheet feeding device 10 and the inkjet head 2 located upstream.

  In the first and second embodiments, when only one type of paper having a paper length along the transport path is transported, the upstream of the inkjet head 2 located at the most upstream position at the position corresponding to the paper length. It is sufficient to provide a plurality of sensors. In the first and second embodiments, when a sheet having three or more sheet lengths along the conveyance path is conveyed, a sensor may be further added according to the sheet size. In addition, the moving mechanism in the third embodiment may be any moving mechanism as long as the sensor can be moved.

1 is a perspective view showing an external appearance of an ink jet printer according to a first embodiment of the present invention. It is a schematic side view which shows the internal structure of the inkjet printer shown in FIG. It is a schematic diagram which shows the separation distance of the sensor with respect to an inkjet head. It is a block diagram which shows schematic structure of the control part shown in FIG. It is a schematic side view which shows the internal structure of the inkjet printer by 2nd Embodiment of this invention. It is a schematic side view which shows the internal structure of the inkjet printer by 3rd Embodiment of this invention. It is a schematic perspective view of the moving mechanism shown in FIG. It is a block diagram which shows schematic structure of the control part shown in FIG.

Explanation of symbols

1,201,301 Inkjet printer (inkjet recording device)
2 Inkjet head 2a Discharge surface 10 Paper feeding device 21a, 21b, 22a, 22b Feed roller 50 Belt conveying device 80, 89, 294 Sensor (first sensor)
81,90 sensor (second sensor)
82,91 sensor (third sensor)
83,92 sensor (4th sensor)
88,97 sensor (5th sensor)
100, 200, 300 Control unit (control means)
350 Moving mechanism

Claims (6)

An inkjet head having an ejection surface for ejecting ink;
A transport mechanism capable of transporting along a different recording medium length along the transport path from each other in the transport path,
Control means for controlling the transport mechanism so as to transport the recording medium to a position facing the ejection surface, and for controlling the inkjet head so as to eject ink based on print data to the recording medium;
A first sensor that is disposed upstream of the inkjet head along the transport path and detects a front end of the recording medium transported by the transport mechanism;
When the front end of the recording medium disposed upstream of the first sensor and transported by the transport mechanism along the transport path is downstream of the upstream side surface of the inkjet head, the rear end of the recording medium is A second sensor to detect,
When the second sensor does not detect the trailing edge of the recording medium after the first sensor detects the leading edge of the recording medium and before a predetermined time elapses, the control means discharges ink to the recording medium. The inkjet head is controlled so as to stop , and the inkjet head is controlled to start ejecting ink to the recording medium after a predetermined time has elapsed after the first sensor detects the front end of the recording medium. An ink jet recording apparatus. A plurality of the inkjet heads arranged in one direction along the transport path;
The recording medium when the front end of the recording medium disposed upstream of the inkjet head disposed upstream in the one direction and conveyed by the conveying mechanism is between two adjacent inkjet heads A third sensor for detecting the rear end of the
When the third sensor does not detect the trailing edge of the recording medium after the second sensor detects the trailing edge of the recording medium and until a predetermined time elapses, the control means performs ink for the recording medium. an ink jet recording apparatus according to claim 1, wherein the controller controls the ink jet head so as to stop the discharge. The inkjet in which the front end of the recording medium that is arranged upstream of the inkjet head arranged in the most upstream direction and conveyed by the conveyance mechanism is arranged downstream of the two inkjet heads in the one direction A fourth sensor for detecting the trailing edge of the recording medium when it is downstream of the upstream side surface of the head;
When the fourth sensor does not detect the trailing edge of the recording medium between the time when the third sensor detects the trailing edge of the recording medium and a predetermined time elapses, the control means performs ink for the recording medium. The inkjet recording apparatus according to claim 2 , wherein the inkjet head is controlled so as to stop the ejection. When the front end of the recording medium which is arranged upstream of the inkjet head arranged upstream and is conveyed by the conveyance mechanism is downstream from the inkjet head arranged most downstream with respect to the one direction. And a fifth sensor for detecting the rear end of the recording medium,
When the fifth sensor does not detect the trailing edge of the recording medium after the fourth sensor detects the trailing edge of the recording medium and until a predetermined time elapses, the control means performs ink for the recording medium. The inkjet recording apparatus according to claim 3 , wherein the inkjet head is controlled so as to stop the ejection. The second sensor is an ink jet recording apparatus according to claim 1, wherein a length along the transport path are plural arranged according to different recording medium. The inkjet recording apparatus according to claim 1, further comprising a moving mechanism that moves the first sensor and the second sensor according to recording media having different lengths along the conveyance path.

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