Image forming apparatus

Abstract

To enable printing even while a thick portion passes a recording head without moving the recording head.SOLUTION: An image forming apparatus includes: a recording head which discharges liquid droplets to a recording medium to form an image; a detection mechanism which is disposed on a transport path on the upstream side of a recording region, and detects a thick portion having a thickness greater than other portions of the recording medium; and a movement mechanism which constitutes a part of a conveyance mechanism, is disposed respectively on the upstream and downstream sides of the recording region, holds the recording medium in a movable manner, and is movable in a direction in which the recording medium and the recording head face each other. On the basis of a detection result of the thick portion by the detection mechanism, while the thick portion passes through the recording region, the movement mechanism is moved from a normal position to a separation position that is separated from the recording head by an amount corresponding to the thickness of the thick portion, image formation by the recording head is allowed to continue in a state where the movement mechanism is moved to the separation position, and the movement mechanism is returned from the separation position to the normal position after the thick portion has passed through the recording region.SELECTED DRAWING: Figure 1B

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] There is a known image forming apparatus that forms an image by ejecting droplets from a recording head onto a long strip of recording medium (continuous paper) while conveying the recording medium in the longitudinal direction using a conveying mechanism (rollers) (see Figure 1E). This type of image forming apparatus can print multiple independent images sequentially in the longitudinal direction of the paper.

[0003] A post-processing machine that performs post-processing on the printed continuous paper is often located downstream of an image forming device that prints on continuous paper. Examples of post-processing machines include another image recording device that records an image on the back side of the paper, a cutting device that cuts the paper, a folding device that folds the paper, and a half-cutting device that cuts only the seal layer of a paper sheet that consists of a backing layer and a seal layer. In such image forming devices, a technique is known that moves the recording head to a retracted position away from the paper when the splice portion (thick portion) of the paper reaches the recording head to prevent the splice portion from colliding with the recording head (see Patent Documents 1 to 3). DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] However, in the image forming apparatuses described in Patent Documents 1 to 3, printing is disabled while the recording head is being moved to the retracted position, which causes problems such as delays in the post-processing machine, reduced productivity, and the generation of wasted paper. Another problem is that when the recording head is returned from the retracted position to the printing position, it takes time for the return operation to position the recording head with high precision.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to make it possible to print while a thick portion passes over a recording head without moving the recording head. [Means for solving the problem]

[0006] In order to achieve the above object, the image forming apparatus of the present invention forms an image on a long, strip-shaped recording medium while transporting the recording medium in a longitudinal direction using a transport mechanism, and includes a recording head that is arranged opposite a recording area on the transport path of the recording medium and forms an image on the recording medium by ejecting droplets onto the recording medium that has arrived at the recording area; a detection mechanism that is arranged on the transport path upstream of the recording area and detects thick portions of the recording medium that are thicker than other portions; and a moving mechanism that constitutes part of the transport mechanism, which is arranged respectively upstream and downstream of the recording area and is capable of moving in a direction in which the recording medium and the recording head face each other while holding the recording medium in a movably manner, and based on the detection result of the thick portion by the detection mechanism, moves the moving mechanism from a normal position to a spaced position away from the recording head by the thickness of the thick portion while the thick portion passes through the recording area, and allows the recording head to continue forming an image while the moving mechanism is moved to the spaced position, and returns the moving mechanism to the normal position after the thick portion has passed through the recording area. [Effects of the Invention]

[0007] According to the present invention, printing can be performed while the thick portion passes the recording head without moving the recording head. [Brief explanation of the drawings]

[0008] [Figure 1A] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention, showing a state in which a splice portion of a sheet is detected by a sensor; [Figure 1B] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention, showing a state in which a moving mechanism is lowered and a predetermined gap is formed between a splice portion and a recording head. [Figure 1C]FIG. 10 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention, illustrating a state in which the movement mechanism rises after the splice portion has passed the recording head, forming a predetermined gap between the paper and the recording head. [Figure 1D] FIG. 2 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention, illustrating a state in which a sensor detects the descent of a moving mechanism. [Figure 1E] FIG. 1 is a schematic diagram of a conventional image forming apparatus. [Figure 2A] FIG. [Figure 2B] FIG. 10 is an elevation view of the moving mechanism when (a) it is rising and (b) it is falling. [Figure 3] (a) Plan view and (b) cross-sectional view of the splice portion. [Figure 4] FIG. 1 is an elevation view of a sensor for detecting a splice. [Figure 5] FIG. 1 is a perspective view of an image forming apparatus that prints on fabric. [Figure 6A] FIG. 10 is a schematic diagram of an image forming apparatus according to a modified embodiment of the present invention, showing a state in which a splice portion of a sheet is detected by a sensor. [Figure 6B] FIG. 10 is a schematic diagram of an image forming apparatus according to a modified embodiment of the present invention, showing a state in which the abutting mechanism has descended and a predetermined gap has been formed between the splice portion and the recording head. [Figure 6C] FIG. 10 is a schematic diagram of an image forming apparatus according to a modified embodiment of the present invention, showing a state in which the abutting mechanism operates to set the return position of the lifting roller while the splice portion passes the recording head. [Figure 6D] FIG. 10 is a schematic diagram of an image forming apparatus according to a modified embodiment of the present invention, showing a state in which the lifting rollers have returned to their original position and are ready to print the next sheet of paper. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of an image forming apparatus according to the present invention will be described below with reference to the drawings. As shown in Figures 1A-1D, 2A, and 2B, an image forming apparatus 10 according to this embodiment has a supply roll 11 that supplies continuous paper P as a long strip-shaped recording medium, and a take-up roll 12 that takes up the printed continuous paper P.

[0010] A main body 13 of the image forming device 10 is disposed between an upstream supply roll 11 and a downstream take-up roll 12. Within this main body 13, an entrance roller, two lifting rollers 15 and 16, a guide roller 17, and an exit roller 18 are disposed, which constitute a transport mechanism for the continuous paper P. A hot air heater 21 for drying the printed continuous paper P can be disposed between the guide roller 17 and the exit roller 18.

[0011] The transport mechanism can be configured, for example, with a transport motor and multiple rollers. However, the lift rollers 15 and 16 may or may not have a driving force. The lift rollers 15 and 16 can also be configured with rollers for supporting paper or platen rollers.

[0012] A sensor 19 is disposed between the entrance roller and the lift roller 15 as a detection mechanism for detecting the thickness of the paper. This sensor 19 is used to detect thick portions of the paper that are thicker than other portions, and in this embodiment is configured to detect the splice portion Pa of the continuous paper P.

[0013] Inkjet head Four inkjet heads 20Y, 20M, 20C, and 20K that make up the recording head are disposed between the lifting rollers 15 and 16. These four heads 20Y-20K are disposed adjacent to one another in order from the upstream side to the downstream side in the transport direction.

[0014] The arrangement order of the four heads 20Y-20K in the transport direction may be different from that shown in Fig. 1A. A single monochrome printing head may be provided instead of the inkjet heads 20Y, 20M, 20C, and 20K.

[0015] The inkjet head 20Y is an inkjet head that ejects yellow ink, the inkjet head 20M is an inkjet head that ejects magenta ink, the inkjet head 20C is an inkjet head that ejects cyan ink, and the inkjet head 20K is an inkjet head that ejects black ink.

[0016] Inkjet heads 20Y, 20M, 20C, and 20K can record full-color images on continuous paper P. Inkjet heads 20Y, 20M, 20C, and 20K have the same configuration.

[0017] The ink of each color is stored in an ink tank for each color, flows through an ink flow path for each color, and is supplied to the inkjet head of the corresponding color among the inkjet heads 20Y, 20M, 20C, and 20K. In Fig. 2A, the ink tanks for each color and the ink flow paths for each color are omitted.

[0018] The inkjet heads 20Y, 20M, 20C, and 20K each include a plurality of nozzles, which are provided on the ejection surface on the lower surface of the head.

[0019] The ejection surface faces the conveyance surface of the continuous paper P between the conveyance rollers 15 and 16. The ejection surface is parallel to the conveyance surface.

[0020] Inkjet heads 20Y, 20M, 20C, and 20K are line-type inkjet heads. In line-type inkjet heads 20Y, 20M, 20C, and 20K, a plurality of nozzles are arranged in the width direction of continuous paper P (the direction perpendicular to the paper surface of FIG. 1A).

[0021] The width direction is a direction perpendicular to the conveyance direction. The width direction is perpendicular to the longitudinal direction of the continuous paper P and coincides with the lateral direction of the continuous paper P.

[0022] A plurality of nozzle rows each having nozzles arranged in the width direction may be arranged in the transport direction. The arrangement and number of the plurality of nozzles can be determined appropriately taking into consideration various conditions.

[0023] Lifting rollers The lifting rollers 15, 16 are made up of a pair of upper and lower rollers that sandwich the continuous paper P from above and below. The lifting rollers 15, 16 movably support the continuous paper P. The rollers 15', 16' of conventional image forming devices 10 are not configured to be able to be raised and lowered as shown in Figure 1E, and in most cases the inkjet heads 20Y, 20M, 20C, 20K can be retracted above the continuous paper P to avoid collision with the splice part Pa.

[0024] As shown in Figures 2A and 2B, both ends of the shafts of the pair of upper and lower rollers are supported by four roller support plates 30. The four roller support plates 30 are configured to move up and down simultaneously in the vertical direction (direction of the arrows).

[0025] Therefore, the continuous paper P between the upstream lifting roller 15 and the downstream lifting roller 16 is configured to be able to move parallel in the vertical direction while facing the head undersides (discharge surfaces) of the inkjet heads 20Y, 20M, 20C, and 20K.

[0026] The roller support plate 30 is connected to a lifting means such as a solenoid, and is configured so that the roller support plate 30 and the lifting rollers 15 and 16 move up and down in the direction of the arrow in FIG. 2A (vertical direction) based on the detection result of the sensor 19.

[0027] 1A, the lifting rollers 15 and 16 are in the raised position (normal position) until the splice portion Pa of the continuous paper P arrives directly below the sensor 19, and a predetermined distance suitable for the flight of printing droplets is formed between the ejection surfaces of the inkjet heads 20Y, 20M, 20C, and 20K and the continuous paper P. In this state, the recording area of ​​the paper is printed with droplets ejected from the inkjet heads 20Y, 20M, 20C, and 20K.

[0028] After the splice portion Pa of the continuous paper P passes directly below the sensor 19, the lifting rollers 15 and 16 move to the lowered position (separated position) as shown in Figure 1B. Then, while the splice portion Pa passes the inkjet heads 20Y, 20M, 20C, and 20K, the lifting rollers 15 and 16 are spaced apart from the ejection surfaces of the inkjet heads 20Y, 20M, 20C, and 20K by an additional distance equivalent to the thickness of the splice portion Pa.

[0029] Therefore, even in this separated state, a predetermined distance suitable for droplet flight is formed between the ejection surfaces of inkjet heads 20Y, 20M, 20C, and 20K and splice portion Pa of the continuous paper P. This means that droplets ejected from inkjet heads 20Y, 20M, 20C, and 20K can be used to print on splice portion Pa of the continuous paper P. Therefore, even while lift rollers 15, 16 are moving to the separated position, printing by inkjet heads 20Y, 20M, 20C, and 20K can continue while transporting the continuous paper P at a constant speed.

[0030] After the splice portion Pa of the continuous paper P passes through the inkjet heads 20Y, 20M, 20C, and 20K, the lifting rollers 15 and 16 return to their raised positions (normal positions), as shown in Figure 1C. Then, droplets are ejected from the inkjet heads 20Y, 20M, 20C, and 20K onto the continuous paper P upstream of the splice portion Pa, printing the recording area of ​​the paper.

[0031] ● Lower stopper and upper stopper 2A and 2B, a lower stopper 40 serving as a first stopper and an upper stopper 41 serving as a second stopper are disposed above and below the roller support plate 30. The upper stopper 41 is omitted in FIG. 2A.

[0032] The height positions of the lower stopper 40 and the upper stopper 41 can be determined according to the thickness of the splice portion Pa. The roller support plate 30 comes into contact with the lower stopper 40 and the upper stopper 41, thereby restricting the elevation position of the roller support plate 30.

[0033] 1B, the lowered position (separated position) of the lift rollers 15, 16 is restricted by a lower stopper 40. In addition, in FIG. 1C, the raised position (normal position) of the lift rollers 15, 16 after the return operation is restricted by an upper stopper 41.

[0034] In this way, the elevation positions of the lifting rollers 15, 16 are regulated by the lower stopper 40 and the upper stopper 41, which are mechanically configured to abut against each other, so that the elevation positions of the lifting rollers 15, 16 can be quickly and accurately determined. Another advantage is that the lower stopper 40 and the upper stopper 41 have a simple structure and can be installed at low cost.

[0035] This embodiment shortens the retraction time of the lift rollers 15 and 16 when the splice portion Pa passes the inkjet heads 20Y, 20M, 20C, and 20K, improving productivity and reducing paper waste. Furthermore, because the inkjet heads 20Y, 20M, 20C, and 20K are not retracted, printing can continue even while the transport rollers 15 and 16 are retracted. For example, a marker for identifying the post-processing machine can be printed at the splice portion Pa. In other words, as shown in FIG. 3, a sort mark SM or a cut mark CM can be printed at or near the splice portion Pa, preventing delays in post-processing such as sorting and paper cutting.

[0036] ●Splice part 3 and 4, a splice portion Pa may be formed along the conveying direction of a long continuous piece of paper P. The splice portion Pa is a portion where the rear end of the downstream continuous piece of paper P1 and the front end of the upstream continuous piece of paper P2 are joined using adhesive tape C or the like.

[0037] 4, the thickness Ts of the splice portion Pa is formed by attaching adhesive tape C to both sides of a pair of main surfaces of the continuous paper P, and is therefore greater than the thickness Tp of the other portions (non-spliced ​​portions) of the continuous paper P by the thickness of the adhesive tape C. The image forming device 10 according to this embodiment is applied to an image forming device that uses continuous paper P having such a splice portion Pa (seam) as a printing medium.

[0038] That is, when splice portion Pa passes under inkjet heads 20Y, 20M, 20C, and 20K, if the thickness Ts of splice portion Pa in Figure 4 is greater than the distance between the continuous paper P and inkjet heads 20Y, 20M, 20C, and 20K, splice portion Pa may rub against and damage inkjet heads 20Y, 20M, 20C, and 20K. For this reason, in this embodiment, before splice portion Pa passes under inkjet heads 20Y, 20M, 20C, and 20K, sensor 19 detects splice portion Pa, and the position of the continuous paper P is moved from the normal position in Figure 1A to the separated position in Figure 1B.

[0039] ●Detection mechanism for thick parts In this embodiment, a sensor 19 is provided as a mechanism for detecting thick portions of the paper that are thicker than other portions. The sensor 19 is located upstream of the inkjet heads 20Y, 20M, 20C, and 20K. In this embodiment, the sensor 19 is located between the inlet roller 14 and the lift roller 15.

[0040] The sensor 19 can be configured with a transmitter 19a and a receiver 19b that sandwich the continuous paper P from above and below, as shown in Figure 4. The transmitter 19a and receiver 19b can detect the splice Pa formed in the continuous paper P without contact.

[0041] That is, a signal such as laser light or ultrasound is transmitted from the transmitting unit 19a to the receiving unit 19b, and the thickness of the continuous sheet of paper P interposed between the transmitting unit 19a and the receiving unit 19b can be detected depending on the reception status of the receiving unit 19b.

[0042] When detecting the splice portion Pa, for example, as shown in Figure 4, the seam of the continuous sheet of paper P is glued together with adhesive tape C, so there is a difference between the thickness Tp of the normal part (non-spliced ​​part) of the continuous sheet of paper P and the thickness Ts of the splice portion Pa, and the difference between these thicknesses is detected as the splice portion Pa.

[0043] The sensor 19 may be an optical sensor, or it may be a sensor that detects the thickness of the continuous paper P by the transmittance of laser light or ultrasonic waves. In the case of an optical sensor, the thick portion of the continuous paper P is indirectly detected by detecting a splice mark pre-printed on the surface of the splice portion Pa with a reflective optical sensor.

[0044] While the present invention has been specifically described above based on an embodiment, it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways within the scope of the technical concept described in the claims. For example, a distance measuring sensor 22 can be provided as shown in FIG. 1D to confirm that the lift rollers 15, 16 have been raised and lowered. The distance measuring sensor 22 can reliably detect that the lift rollers 15, 16 have descended to the separated position and that they have ascended to the normal position. If the lift rollers 15, 16 cannot be confirmed to have been raised and lowered, the distance measuring sensor 22 can issue an error signal, causing the image forming apparatus 10 to stop printing, thereby reducing the occurrence of paper waste due to errors.

[0045] The recording medium may be, for example, fabric other than continuous paper P. Figure 5 shows an example of an image forming apparatus that uses fabric F as the recording medium. Inkjet heads 20Y, 20M, 20C, and 20K are fixedly arranged on a horizontal base 53, and a pattern Fa can be formed in the recording area on the upper surface of the fabric F.

[0046] The fabric F is conveyed in the conveying direction indicated by the arrow by a pair of rollers 50, 51 serving as a conveying mechanism, a motor 52 that drives the roller 51, and a belt B that is wound around the rollers 50, 51. Elevating rollers 15, 16 are disposed on both sides of the inkjet heads 20Y, 20M, 20C, and 20K in the conveying direction. The upper belt B and fabric F are sandwiched between the elevator rollers 15, 16, thereby supporting the upper belt B and fabric F so that they can move in the vertical direction.

[0047] ●Continuous printing of multiple paper types with different paper thicknesses When continuously printing a continuous web of paper P made up of multiple paper types (paper sheets) of different thicknesses joined (spliced), it is necessary to adjust the gap (head gap) between the continuous web of paper P and inkjet heads 20Y, 20M, 20C, and 20K to an appropriate distance, with splice portion Pa as the boundary. For this reason, in the conventional image forming device 10 shown in Figure 1E, when a different paper type (at splice portion Pa) arrives at image forming device 10, continuous printing is temporarily stopped, and the user has to reset the new paper type that has arrived at image forming device 10 on the operation panel (head gap readjustment).

[0048] However, if the user has to operate the operation panel one by one to adjust the thickness of each new paper type, the printing stop time will be longer, which will reduce productivity. There is also the possibility that the user may operate the operation panel incorrectly.

[0049] 6A-6D, in a modified embodiment of the present invention, a paper thickness sensor 60 that continuously (online) detects the thickness of the paper is provided immediately upstream of the sensor 19, in addition to the sensor 19 that detects the splice portion Pa of the continuous paper P. Also, abutment mechanisms 71 and 72 that can move up and down are provided relative to the lift rollers 15 and 16.

[0050] 2A and 2B, the abutment mechanisms 71 and 72 can be configured with a lower stopper 40 which is the first stopper and an upper stopper 41 which is the second stopper. The abutment mechanisms 71 and 72 can also be provided with the lower stopper 40 and the upper stopper 41 separately.

[0051] When the splice portion Pa of the continuous paper P reaches the position of sensor 19, sensor 19 detects the thickness of the splice portion Pa, and paper thickness sensor 60 also detects the thickness of the continuous paper P. Various types of paper thickness sensor 60 are possible, and for example, a non-contact type can be used, such as a capacitance type paper thickness sensor that uses the electrodes of a flat capacitor as the thickness detection sensing element, or a light transmission type paper thickness sensor that measures the paper thickness based on the transmittance of light passing through the continuous paper P in the vertical direction.

[0052] In addition, the contact type can use a pair of transport rollers that sandwich the top and bottom of the continuous paper P. One of the pair of transport rollers is a drive roller with a fixed shaft height, and the other is a driven roller whose shaft height varies depending on the paper thickness. The thickness of the continuous paper P can be detected online by detecting the up and down movement of the driven roller with a displacement sensor.

[0053] The positions of sensor 19 and paper thickness sensor 60 can be reversed, with sensor 19 located upstream and paper thickness sensor 60 located downstream. Also, sensor 19, which detects splice portion Pa of continuous paper P, can be combined with (shared with) paper thickness sensor 60. This allows image forming apparatus 10 to be made smaller and less expensive.

[0054] When the splice portion Pa approaches the most upstream inkjet head 20Y, the lift rollers 15 and 16 are retracted (downward) away from the head, as shown in Figures 6B and 6C. At the same time as the lift rollers 15 and 16 are retracted, the abutment mechanisms 71 and 72 can be moved up and down to maintain a constant head gap depending on the paper thickness of the next paper type. For example, if the next new paper is thicker than the previous paper, the lift rollers 15 and 16 can be lowered in a direction that increases the distance between the inkjet heads 20Y, 20M, 20C, and 20K and the continuous paper P.

[0055] Generally, head gap adjustment requires highly accurate positioning using an encoder, etc. In this embodiment, the elevating rollers 15 and 16 are retracted as shown in Figures 6B and 6C, and the abutment mechanisms 71 and 72 are operated while the splice portion Pa passes by the inkjet heads 20Y, 20M, 20C, and 20K, thereby enabling the elevating rollers 15 and 16 to be returned to their original positions early.

[0056] 6D, this allows the lift rollers 15 and 16 to quickly return to their original position after the splice Pa passes the head, enabling the next printing to be resumed promptly. Therefore, even when continuous printing is performed on continuous paper P in which multiple paper types with different paper thicknesses are spliced ​​together, the productivity of the image forming apparatus 10 does not decrease (reduced downtime).

[0057] <Additional Notes> Preferred embodiments of the present invention will be described below. <First aspect> In a first aspect, an image forming device forms an image on a long, strip-shaped recording medium while transporting the recording medium in a longitudinal direction using a transport mechanism, the image forming device comprising: a recording head that is arranged opposite a recording area on the transport path of the recording medium and forms an image on the recording medium by ejecting droplets onto the recording medium that has reached the recording area; a detection mechanism that is arranged on the transport path upstream of the recording area and detects thick portions of the recording medium that are thicker than other portions; and a moving mechanism that constitutes part of the transport mechanism, which is arranged upstream and downstream of the recording area and can move in a direction in which the recording medium and the recording head face each other while holding the recording medium in a movable state.Based on the detection result of the thick portion by the detection mechanism, the moving mechanism is moved from a normal position to a spaced position away from the recording head by the thickness of the thick portion while the thick portion passes through the recording area, and while the moving mechanism is moved to the spaced position, image formation by the recording head can continue, and the moving mechanism is returned from the spaced position to the normal position after the thick portion has passed through the recording area. <Second mode> The second aspect is the image forming apparatus of the first aspect, characterized in that a first stopper is arranged at the separated position of the moving mechanism, and the moving mechanism is positioned at the separated position by abutting against the first stopper when the moving mechanism moves from the normal position to the separated position. <Third aspect> A third aspect is an image forming apparatus of the first or second aspect, characterized in that a second stopper is arranged at the normal position of the moving mechanism, and the moving mechanism is positioned at the normal position by abutting against the second stopper when the moving mechanism moves from the separated position to the normal position. <Fourth aspect> A fourth aspect is an image forming apparatus according to any one of the first to third aspects, characterized in that a post-processing machine is disposed downstream of the recording area, and when the moving mechanism is moved to the separated position, an identification marker that serves as a reference for post-processing by the post-processing machine is formed on the recording medium by the recording head. <Fifth aspect> A fifth aspect is the image forming apparatus according to any one of the first to fourth aspects, further comprising a sensor that detects that the movement mechanism has moved to the separated position. <Sixth aspect> A sixth aspect is the image forming apparatus according to any one of the first to fifth aspects, further comprising a sensor that detects that the movement mechanism has returned to the normal position. <Seventh aspect> A seventh aspect is an image forming device that forms an image on a long, strip-shaped recording medium, which is made up of multiple types of media with different thicknesses, while transporting the recording medium longitudinally using a transport mechanism.The image forming device includes a recording head that is arranged opposite a recording area on the transport path of the recording medium and forms an image by ejecting droplets onto the recording medium that has arrived at the recording area, a detection mechanism that is arranged on the transport path upstream of the recording area and detects the thickness of the recording medium, and a movement mechanism that forms part of the transport mechanism, which is arranged respectively upstream and downstream of the recording area and is capable of moving the recording medium in a direction facing the recording head while movably holding the recording medium, and the movement mechanism enables the recording head to form an image while maintaining a constant gap between the recording head and the recording medium based on the detection results of the detection mechanism. <Eighth aspect> An eighth aspect is the image forming apparatus of the seventh aspect, characterized in that the moving mechanism has a first stopper that regulates the position of the recording medium in a direction away from the recording head, and a second stopper that regulates the position of the recording medium in a direction approaching the recording head. <Ninth aspect> A ninth aspect is the image forming apparatus of the eighth aspect, characterized in that the first stopper and the second stopper are arranged to be movable in a direction in which the recording medium and the recording head face each other based on the detection result of the detection mechanism. <Tenth aspect> A tenth aspect is an image forming apparatus according to any one of the seventh to ninth aspects, characterized in that the detection mechanism for detecting the thickness of the recording medium according to the seventh aspect is combined with the detection mechanism for detecting the thick portion according to the first aspect. [Explanation of symbols]

[0058] 10: Image forming device 11: Supply roll 12: Winding roll 13: Main body 14: Entrance roller 15, 16: Lifting rollers 17: Guide roller 18: Exit roller 19: Sensor (detection mechanism) 19a: Transmitting unit 19b: Receiving section 20Y, 20M, 20C, 20K: Inkjet head (recording head) 21: Hot air heater 22: Distance measurement sensor 30: Roller support plate 40: Lower stopper (first stopper) 41: Upper stopper (second stopper) 50, 51: Rollers 52: Motor 53: Base 60: Paper thickness sensor 71, 72: Abutment mechanism B: Belt C: Adhesive tape CM: Cut mark F: Fabric Fa: Pattern P, P1, P2: Continuous paper (recording medium) Pa: Splice part (thick part) SM: Sort mark Tp, Ts: thickness [Prior art documents] [Patent documents]

[0059] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-046260 [Patent Document 2] Japanese Patent Application Publication No. 2017-177059 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-144895

Claims

1. An image forming apparatus that forms an image on a long strip-shaped recording medium while conveying the recording medium in a longitudinal direction by a conveying mechanism, a recording head disposed opposite a recording area on a transport path of the recording medium, and configured to form an image by ejecting droplets onto the recording medium that has arrived at the recording area; a detection mechanism disposed on the conveyance path upstream of the recording area, for detecting a thick portion of the recording medium that is thicker than other portions; a moving mechanism constituting a part of the transport mechanism, the moving mechanism being disposed on the upstream side and downstream side of the recording area, and capable of moving the recording medium in a direction in which the recording medium and the recording head face each other while movably holding the recording medium; an image forming apparatus, characterized in that, based on the detection result of the thick portion by the detection mechanism, the moving mechanism is moved from a normal position to a separated position away from the recording head by an amount equal to the thickness of the thick portion while the thick portion passes through the recording area, and image formation by the recording head can be continued while the moving mechanism is moved to the separated position, and the moving mechanism is returned from the separated position to the normal position after the thick portion has passed through the recording area.

2. 2. The image forming apparatus according to claim 1, wherein a first stopper is disposed at the separated position of the moving mechanism, and the moving mechanism is positioned at the separated position by abutting against the first stopper when the moving mechanism moves from the normal position to the separated position.

3. 2. The image forming apparatus according to claim 1, wherein a second stopper is disposed at the normal position of the moving mechanism, and the moving mechanism is positioned at the normal position by abutting against the second stopper when moving from the separated position to the normal position.

4. 2. The image forming apparatus according to claim 1, wherein a post-processing device is disposed downstream of the recording area, and when the moving mechanism is moved to the separated position, an identification marker that serves as a reference for post-processing by the post-processing device is formed on the recording medium by the recording head.

5. 2. The image forming apparatus according to claim 1, further comprising a sensor for detecting when said moving mechanism has moved to said separated position.

6. 2. The image forming apparatus according to claim 1, further comprising a sensor for detecting when said moving mechanism has returned to said normal position.

7. An image forming apparatus that forms an image on a long strip-shaped recording medium, which is made up of multiple types of media with different thicknesses connected together, while conveying the recording medium in a longitudinal direction by a conveying mechanism, a recording head disposed opposite a recording area on a transport path of the recording medium, and configured to form an image by ejecting droplets onto the recording medium that has arrived at the recording area; a detection mechanism disposed on the transport path upstream of the recording area and detecting a thickness of the recording medium; a moving mechanism constituting a part of the transport mechanism, the moving mechanism being disposed on the upstream side and downstream side of the recording area, and capable of moving the recording medium in a direction in which the recording medium and the recording head face each other while movably holding the recording medium; An image forming apparatus characterized in that, based on the detection result of the detection mechanism, the moving mechanism enables image formation by the recording head while maintaining a constant gap between the recording head and the recording medium.

8. 8. The image forming apparatus according to claim 7, wherein the moving mechanism has a first stopper that regulates the position of the recording medium in a direction away from the recording head, and a second stopper that regulates the position of the recording medium in a direction approaching the recording head.

9. 9. The image forming apparatus according to claim 8, wherein the first stopper and the second stopper are arranged to be movable in a direction in which the recording medium and the recording head face each other based on the detection result of the detection mechanism.

10. 8. An image forming apparatus according to claim 7, wherein the detection mechanism for detecting the thickness of the recording medium according to claim 7 is combined with the detection mechanism for detecting the thick portion according to claim 1.

Images