JP5721525B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that conveys an envelope in a conveyance path for the purpose of printing.

  The spread of printers capable of high-speed color printing at a low price is remarkable. The printer is connected to a terminal such as a personal computer, captures image information such as characters, illustrations, and symbols produced at the terminal, and prints it on a recording medium. Further, in a composite printer integrated with a scanner or a facsimile, it is possible to print image information captured from a scanner unit, or to print image information transferred by a facsimile.

  In printers, recording media such as plain paper, photo paper, glossy paper, and OHP film are used for printing. For home use, printers that print on recording media from postcard size to A4 size are generally used. For office use, for example, printers that print on recording media from postcard size to A3 size are used.

  In the printer, a recording medium such as plain paper is stored in a paper feed tray, and when a printing operation is started, the plain paper stored in the paper feed tray is fed to the transport path using a paper transport device. The paper transport device transports plain paper along the transport path to the registration rollers by the rotation of the transport roller. The plain paper conveyed up to the registration roller is subjected to skew correction and the like, and the plain paper is conveyed from the registration roller to the printing unit in accordance with the sending timing. In the printing unit, printing is performed on plain paper, and the printed plain paper is sent to a paper discharge tray.

  In the paper transport device, in order to improve productivity when the number of printed sheets is large, the plain paper is fed (sheeted) one by one from the paper feed tray to the transport path, and the regular paper transport interval is kept constant. It is necessary to make the plain paper reach the registration roller at an appropriate timing. The following Patent Document 1 mainly corrects the delay or advance of plain paper supplied from the paper feed tray to the transport path by acceleration / deceleration processing of the intermediate transport means, and stabilizes the arrival timing of plain paper to the registration rollers. A paper transport device that can do this is disclosed.

JP 2009-161320 A

  However, in the paper transport device disclosed in Patent Document 1, the following points have not been considered.

  With improvements in performance such as printing speed and printing quality, there is an increasing demand for printing a large amount of envelopes (sacks) used for advertisements and promotions using a printer. One printing medium is used for normal printer printing, but the number and thickness of the printing medium itself vary depending on the part of the envelope. Envelopes have a rectangular shape that contains letters, sentences, etc., and is created by folding paper. The main body (envelope main body) is sealed on the three sides of this square shape, and is created on the remaining one side of the main body. And a flap (folding lid) for folding and binding after enclosing a letter or the like. For this reason, the main body has a portion in which the paper is folded into two sheets and a portion in which three sheets of glued paper are further stacked, and the thickness of the main body is thick. Further, when the flap is not folded back (when the flap is opened), it is one sheet, and the thickness of the flap is thin.

  An envelope in which the thickness state changes depending on the part changes the strength of the waist (the strength of the elastic force or the magnitude of the stickiness) depending on the part. Based on the strength of the waist of the envelope body, the flap is weak because it is a single sheet, and the glued portion is strong because it is three sheets.

  In the paper transport device, the envelope is transported with the flap as the rear end side in the transport direction, and the envelope thickness is switched from the thick (two) part of the main body to the thin (one) part of the flap while transporting the transport path. As a result, the load applied to the conveying roller is reduced, which causes excessive feeding. On the other hand, in the paper transport device, the envelope is transported with the flap as the leading end in the transport direction, and the thickness of the envelope is increased from the thin (two) parts of the main body to the thick (three) parts glued during transport along the transport path. When is switched, the load applied to the transport roller becomes heavy, causing slippage between the transport roller and the envelope, resulting in insufficient feeding. For this reason, in the paper transport device, the acceleration / deceleration processing cannot follow the change in the envelope thickness and the change in the waist strength of the envelope, so the timing of arrival of the envelope from the paper feed tray to the registration roller varies. It was difficult to stabilize productivity.

  Further, when the envelope is excessively fed, the leading end side in the transport direction of the envelope interferes with the transport roller, and in the worst case, the leading end side of the envelope is broken and damaged.

  The present invention has been made to solve the above problems. Accordingly, the present invention provides an image forming apparatus that can reduce variations in arrival timing of an envelope whose thickness and waist change in the transport direction to a registration roller, and can stabilize productivity. . Another object of the present invention is to provide an image forming apparatus capable of reducing envelope damage caused by overfeeding of the envelope.

  In order to solve the above-described problems, a first feature of the present invention is that, in the image forming apparatus, a printing unit that performs printing on an envelope and a resist that adjusts a sending timing of the envelope conveyed to the conveyance path to the printing unit. A roller, a conveyance roller that is arranged upstream of the conveyance direction of the registration roller in the conveyance path, conveys the envelope to the registration roller, a conveyance unit drive source that drives the conveyance roller, and a conveyance path that is disposed in the conveyance path. A conveyance sensor that detects a conveyance position of the envelope to be conveyed, an envelope information storage unit that stores envelope information including the size of the envelope body, flaps, and a portion where the paper is overlapped; and an envelope detected using the conveyance sensor Based on the envelope information stored in the conveyance position and the envelope information storage unit, the acceleration / deceleration of the envelope conveyance speed using the conveyance roller of the main body is controlled, and from the envelope conveyance start to the registration roller And a conveyance deceleration control unit for controlling the feeding section driving source to transport the envelope to the registration roller in the conveying time.

  In the image forming apparatus according to the first feature, the transport path includes a paper feed path for transporting the envelope from the paper feeding unit that feeds the envelope to the registration roller, and an inversion of the front and back of the envelope that has been printed on one side in the printing unit. And a reversing transport path for transporting the envelope to the registration roller, and the transport acceleration / deceleration control unit controls acceleration / deceleration of the envelope transported in the paper feed path and the reversing transport path. It is preferable to perform control. Further, in the image forming apparatus according to the first feature, the conveyance acceleration / deceleration control unit includes an acceleration / deceleration of an envelope conveyance speed using a conveyance roller through a conveyance unit driving source in the main body excluding a portion where the flap and the sheet of the envelope are overlapped. Is preferably controlled.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming apparatus includes information on a size of a portion where the main body of the envelope, the flap and the sheet are overlapped, and a conveyance direction of the envelope. Envelope information detecting means for detecting envelope information, envelope shape information acquiring section for storing envelope information detected using the envelope information detecting means, envelope information and envelope information storing section stored in the envelope shape information acquiring section And envelope shape determining means for determining the size of the envelope body, the flap and the overlapped portion of the sheet and the conveying direction of the envelope based on the envelope information stored in the envelope information. Control of the acceleration / deceleration of the envelope conveyed in the conveyance path is performed based on the determined size of the envelope body, the flap and the overlapped portion of the sheet and the conveyance direction of the envelope.

  In the image forming apparatus according to the second feature, the envelope information detection unit includes an envelope shape detection unit that detects a length of the envelope in the conveyance direction, and a thickness of a portion in which the main body, the flap, and the sheet are overlapped in the envelope conveyance direction. It is preferable to provide a medium thickness detection unit that detects

  According to a third aspect of the present invention, in the image forming apparatus according to any one of the first to fourth features, the conveyance acceleration / deceleration control unit satisfies a conveyance time for conveying the envelope to the registration roller within a certain conveyance time. When there is not, control is performed to accelerate the transport speed of the envelope, and when the transport time exceeds a certain transport time, control is performed to decelerate the transport speed.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third features, the conveyance acceleration / deceleration control unit accelerates or decelerates the conveyance speed at a portion where the flap of the envelope and the sheet are overlapped. Is not performed, and the acceleration / deceleration control of the conveyance speed is not performed in the switching between the flap of the envelope and the main body and in the switching between the main body and the sheet overlapped portion.

  According to the image forming apparatus of the first feature of the present invention, the conveyance acceleration / deceleration control unit is configured to use the envelope conveyance position detected by the conveyance sensor and the envelope information stored in the envelope information storage unit. Maintain the constant transport speed using the transport roller in the overlapped part of the flap and paper having different transport conditions with respect to the transport conditions including the thickness of the main body and the strength of the waist, and the longest transport condition as the standard of transport conditions Since the conveyance speed acceleration / deceleration is controlled using the conveyance roller in the main body that does not change, variation in the arrival timing of the envelope to the registration roller can be reduced, and the productivity can be stabilized. Furthermore, in the image forming apparatus according to the first feature, the envelope can be prevented from being fed excessively, so that damage to the envelope can be reduced.

  Further, according to the image forming apparatus according to the first feature, in either case of single-sided printing of an envelope conveyed to the paper feed path, double-sided printing of an envelope conveyed to the reverse conveyance path, Since the acceleration / deceleration of the conveyance speed can be controlled using the acceleration / deceleration control unit, the variation in the arrival timing of the envelope to the registration roller can be reduced, and the productivity can be stabilized.

  According to the image forming apparatus relating to the second feature of the present invention, in addition to the operational effects obtained by the image forming device relating to the first feature, it is detected using the envelope information detecting means and stored in the envelope shape information acquiring unit. Since the conveyance acceleration / deceleration control unit controls the acceleration / deceleration of the envelope based on the envelope information determined using the envelope shape determination means based on the envelope information stored and the envelope information stored in the envelope information storage unit. Acceleration / deceleration control can be performed, and acceleration / deceleration control can be automatically performed without the user performing an operation corresponding to the envelope conveyance direction.

  Further, according to the image forming apparatus according to the first feature or the second feature, the length of the envelope in the conveyance direction is detected using the envelope shape detection unit, and the thickness of the envelope portion is detected using the medium thickness detection unit. Therefore, accurate envelope information can be detected, and as a result, appropriate envelope acceleration / deceleration can be controlled.

  According to the image forming apparatus relating to the third feature of the present invention, in addition to the operational effect obtained by the image forming device relating to the deviation of the first feature or the second feature, the conveyance acceleration / deceleration control unit is used. , When the transport time for transporting the envelope to the registration roller is less than the predetermined transport time, the control is performed to accelerate the transport speed of the envelope, and when the transport time exceeds the predetermined transport time, the control is performed to reduce the transport speed. Variation in arrival timing to the registration roller can be reduced, and productivity can be stabilized.

  According to the image forming apparatus of the fourth feature of the present invention, in addition to the operational effects obtained by the image forming device according to any one of the first to third features, the conveyance acceleration / deceleration control unit is used. In addition, the control of acceleration / deceleration of the conveyance speed is not performed in the envelope flap and the overlapped portion of the paper, and the acceleration / deceleration of the conveyance speed is controlled in the switching between the envelope flap and the main body and the change of the main portion and the paper overlapped portion. Therefore, it is possible to reduce the variation in the arrival timing of the envelope to the registration roller without causing the acceleration / deceleration control to follow the change in the envelope thickness and the change in the strength of the envelope. Can be stabilized.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is an enlarged configuration diagram of a sheet feeding unit and a sheet feeding / conveying unit of an image forming apparatus according to an embodiment. (A) is a front view of a long envelope for printing using the image forming apparatus according to one embodiment, (B) is a back view of the long envelope, and (C) is a cross-sectional view of the long envelope. 1 is a system configuration diagram of an image forming apparatus according to an embodiment. (A) is a schematic cross-sectional view of a recording medium in an image forming apparatus according to an embodiment, and (B) is a diagram illustrating a detection result of the size of the recording medium in a medium size detection unit. FIG. 4A is a schematic cross-sectional view of an envelope in an image forming apparatus according to an embodiment, and FIG. 4B is a diagram illustrating a detection result of the envelope shape in an envelope shape detection unit. (A) is a schematic cross-sectional view of an envelope in the image forming apparatus according to the embodiment, (B) is a diagram showing a detection result of the thickness of the envelope in the medium thickness detection unit, and (C) is an acceleration / deceleration region of the envelope FIG. (A) is a time chart showing the relationship between the conveyance time from the paper feed unit to the registration roller and the conveyance speed of the recording medium or envelope in the image forming apparatus according to the embodiment, and (B) is for explaining the corrected conveyance speed. It is a time chart. 6 is a flowchart illustrating an envelope conveyance control method of the image forming apparatus according to the embodiment.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic and different from actual ones.

  Further, the following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention specifies the arrangement of each component as follows. It is not what you do. The technical idea of the present invention can be variously modified within the scope of the claims.

(Example)
One embodiment of the present invention describes an example in which the present invention is applied to an ink jet printer as an image forming apparatus. Here, the ink jet printer is a color ink jet printer that performs printing using cyan ink, magenta ink, yellow ink, and black ink. The present invention is not necessarily applied only to a color inkjet printer, but can also be applied to a monochrome inkjet printer including a gray scale.

[Configuration of Image Forming Apparatus]
(1) Overall Configuration of Image Forming Apparatus As shown in FIG. 1, an image forming apparatus 1 according to an embodiment supplies a recording medium 100 (and an envelope 100 </ b> E) and a paper feeding unit 2. Transport unit 3 for transporting the recorded recording medium 100, printing unit 6 for printing on the recording medium 100 transported by the transport unit 3, and paper discharge unit 4 for discharging the recorded recording medium 100. And 5 and a control unit 8 for controlling the operation of each of these units.

(2) Configuration of Paper Feed Unit and Paper Discharge Unit As shown in FIGS. 1 and 2, the paper feed unit 2 is not limited to the number and form of the paper feed units 2. 24. The paper feed tray 21 protrudes outward from the housing on the left side of the housing that is not labeled with the image forming apparatus 1 and is detachably disposed. The paper feed trays 22 to 24 are arranged in a stacked state inside the housing. In these sheet feeding trays 21 to 24, an unprinted (before printing) recording medium 100 is stored.

  As shown in FIG. 1, the paper discharge unit 4 includes a paper discharge tray (reference numerals are omitted) provided on the right side surface of the housing so as to protrude outward from the housing. The paper discharge unit 4 is a face-up paper discharge unit, and stores the recording medium 100 that has been printed (after printing) with the printing surface facing upward. Further, the paper discharge unit 5 includes a paper discharge tray (reference numerals are omitted) provided on the upper left side of the housing of the image forming apparatus 1 so as to protrude outward from the housing. The paper discharge unit 5 is a face-down paper discharge unit, and stores the recording medium 100 that has been printed (after printing) in a state where the print surface is faced down.

  Here, recording media such as plain paper, photo paper, inkjet paper, glossy paper, and OHP film are generally used as the recording medium 100. Furthermore, in the image forming apparatus 1 according to the embodiment, an envelope 100E is used as the recording medium 100, and the envelope 100E can be printed. The type and form of the envelope 100E will be described later.

(3) Constitution of Conveying Means As shown in FIG. 1, the conveying means (conveying mechanism) 3 includes a paper feed conveying unit 31, a print conveying unit 32, a rising conveying unit 33, a horizontal conveying unit 34, and a paper discharge. A transport unit 35 and a reverse transport unit 36 are provided.

  As shown in FIGS. 1 and 2, the paper feed / conveying unit 31 includes a recording medium 100 (or envelope 100 </ b> E) from each of the paper feed trays 21 to 24 of the paper feeding unit 2 to the printing / conveying unit 32 (registration roller 37 in this case). ), Paper feed rollers 201 to 204 for supplying the recording medium 100 stored in each of the paper feed trays 21 to 24 to the paper feed route RS, and a recording medium along the paper feed route RS. 100, a conveyance roller 205 that conveys the recording medium 100, and a conveyance roller 206 that conveys the recording medium 100 toward the registration roller 37 along the sheet feeding path RS. Here, “supply” is used in the sense that, for example, the recording medium 100 (or envelope 100E) is sent from the paper feed tray 21 of the paper feed unit 2 to the paper feed path RS. Further, “convey” is used in the sense that, for example, the recording medium 100 (or envelope 100E) is sent from the front side to the rear side around the transport roller 206 in the transport path RS.

  As shown in FIG. 1, the print transport unit 32 includes a transport path RC that transports the recording medium 100 from the paper feed transport unit 31 to the ascending transport unit 33 (here, the registration roller 37 to the preceding stage of the switching unit 325), and the printing unit. And a driving roller 322 for driving the transport belt 321. The transport belt 321 is disposed opposite to the print head 61 and moves in the transport direction.

  A paper discharge conveyance unit 38 is disposed at the end of the print conveyance unit 32, that is, between the switching unit 325 and the paper discharge unit 4. The paper discharge conveyance unit 38 is disposed in the paper discharge route RD1 that guides the recording medium 100 printed by the printing unit 6 and conveyed through the print conveyance unit 32 via the switching unit 325, and the paper discharge route RD1 is provided in the paper discharge route RD1. A paper discharge roller 381 is provided for transporting the recording medium 100 to a paper discharge tray (reference numeral is omitted) along the path RD1. In the image forming apparatus 1 according to the embodiment, the paper discharge conveyance unit 38 is included in the conveyance unit 3.

  The ascending transport unit 33 includes a transport path RV that transports the recording medium 100 from the print transport unit 32 to the horizontal transport unit 34, and transport rollers 331 and 332 that transport the recording medium 100 along the transport path RV. The ascending conveyance unit 33 pushes up and conveys the recording medium 100 in the vertical direction from the print conveyance unit 32 to the horizontal conveyance unit 34 disposed so as to overlap therewith.

  The horizontal conveyance unit 34 conveys the recording medium 100 from the ascending conveyance unit 33 to the paper discharge conveyance unit 35 and the reverse conveyance unit 36 (here, the reverse switching unit 361), and the recording medium 100 along the conveyance route RC. And a transport roller 341 for transporting the ink.

  The paper discharge conveyance unit 35 conveys the recording medium 100 from the end of the horizontal conveyance unit 34, that is, the switching unit 361 to the paper discharge unit 5, and the recording medium 100 to the paper discharge tray along the paper discharge route RD2. And a paper discharge roller 351 to be conveyed. The paper discharge transport unit 35 transports the recording medium 100 printed on one side and printed on one side, and the recording medium 100 printed on both sides and printed on both sides.

  As shown in FIGS. 1 and 2, the reversing and conveying unit 36 is switched again through the switchback unit 364 that reverses the direction of the recording medium 100 in the conveying direction and the switching unit 361 at the end of the horizontal conveying unit 34 through the switchback unit 364. The reverse conveyance path RR that conveys the recording medium 100 to the print conveyance unit 32 and the recording medium 100 conveyed from the horizontal conveyance unit 34 to the switchback unit 364 and the recording medium 100 conveyed from the switchback unit 364 to the print conveyance unit 32, and a reversal switching unit 365 leading to 32, and transport rollers 362, 363, and 366 that transport the recording medium 100 along the reverse transport path RR. The reversing conveyance unit 36 reverses the front and back sides and the conveyance direction while conveying the recording medium 100 that has been printed on one side, and conveys the recording medium 100 to the printing conveyance unit 32 (registration roller 37 in this case) during double-sided printing.

(4) Configuration of Printing Unit As shown in FIG. 1, in the printing unit 6, print heads 61 are arranged on the transport route RC of the print transport unit 32. Although not shown, the print head 61 is an ink jet print head in which ink discharge nozzles are arranged on the transport path RC side and ink is projected from the ink discharge nozzles toward the recording medium 100. The print head 61 arranges a plurality of inks that discharge ink of each color along the conveyance path RC, and arranges a plurality of inks that discharge ink of the same color in a direction intersecting the conveyance path RC (the direction orthogonal thereto). doing. That is, the image forming apparatus 1 according to an embodiment is a color inkjet printer that employs a line printing method in which black ink, cyan ink, magenta ink, and yellow ink are ejected from the print head 61 and printing is performed in line units. . The discharge order of each color ink is not particularly limited with respect to the transport direction.

  Although not necessarily limited to this method, and the configuration thereof is not illustrated in detail, the image forming apparatus 1 according to an embodiment supplies ink to the print head 61 and is not used for printing. An ink circulation unit 62 that collects excess ink and circulates the collected ink again is provided. The ink circulation unit 62 is provided for each color ink. Here, the ink circulation unit 62 for circulating the ink for four colors is provided. The operation of the print head 61 and the ink circulation unit 62 are controlled by the control unit 8.

  In the printing unit 6, the conveyance belt 321 disposed along the conveyance route RC is a circulating belt without a terminal and runs on the surface of the plastic template 63. The conveyance belt 321 conveys (supplies) the recording medium 100 onto the plastic template 63, and conveys (discharges) the recording medium 100 from above the plastic template 63 after printing.

  Further, at least the plastic template 63, the conveyance belt 321 and the conveyance roller 322 constitute a belt platen unit 65 here. The belt platen unit 65 is connected to a lowering mechanism 66. In a normal printing operation, the lowering mechanism 66 holds the belt platen unit 65 close to the print head 61 (via the head gap), aligns the transport path RC and the surface of the transport belt 321, and the recording medium 100. Or the state which can perform conveyance and printing operation of the envelope 100E is maintained. On the other hand, the lowering mechanism 66 moves the entire belt platen unit 65 away from the print head 61 in the recovery processing operation when a conveyance failure occurs, for example, manually by a user operation, so that the conveyance path RC and the conveyance belt 321 are separated. A gap is formed between the surface. This gap is used as a discharge port for discharging (removing) the recording medium 100 or the envelope 100E in which the conveyance failure has occurred.

  A suction device 7 is disposed below the plastic template 63, that is, on the side opposite to the print head 61 (the lower back surface in FIG. 1) around the transport route RC. The suction device 7 has a function of adsorbing the recording medium 100 that is transported and printed by the printing unit 6 to the plastic template 63 through a hole (not shown) of the transport belt 3. In one embodiment, the suction device 7 is an air suction fan. In one embodiment, the suction device 7 is built in the housing of the image forming apparatus 1. However, the suction device 7 is installed as an external device outside the housing of the image forming apparatus 1 and is used as a plastic template by using a suction duct. 63 may be piped below. The suction device 7 is connected to the control unit 8, and the suction operation of the suction device 7 is controlled by the control unit 8.

(5) Sensor Configuration As shown in FIGS. 1 and 2, various detection units are disposed in the transport path of the transport unit 3 of the image forming apparatus 1 according to the embodiment. In the paper feed transport unit 31 of the transport means 3, transport sensors 281, 282, 283, and 285 are disposed in the paper feed path RS. The transport sensor 281 and the like are disposed along the paper feed path RS at the front stage (upstream side in the transport direction) or the rear stage (downstream side in the transport direction) of the transport rollers 205 or 206. Here, the transport sensor 281 or the like determines whether or not the recording medium 100 is transported to an appropriate transport position according to the transport state of the recording medium 100 (or envelope 100E) fed from the paper feed trays 22 to 24, for example, according to the print schedule. In particular, the sheet feeding / conveying unit 31 has a function of detecting whether or not the recording medium 100 is conveyed from the sheet feeding unit 2 to the registration roller 37 in a certain conveying time. The constant conveyance time is substantially the same as the conveyance time of the recording medium 100 or the envelope 100E from the time when the supply and conveyance of the recording medium 100 or the envelope 100E from the paper feeding unit 2 to the time until the registration roller 37 is reached. Used to mean. The function of detecting the transport state (or transport position) is a sensor disposed in the transport path, except for a medium size detection unit 25, a medium thickness detection unit 26, and an envelope shape detection unit 27, which will be described later. In each of the sensors, a registration sensor 286, top edge sensors 287, 288, an upper surface transport inlet sensor 291, a flipper sensor 292, a face down paper discharge sensor 293, an upper surface transport outlet sensor 294, a switchback sensor 295, and a refeed sensor 296. It is the same. For example, an optical sensor can be practically used for the transport sensor 281 and the like.

  Between the registration roller 37 and the coupling region of the sheet feeding path RS from the sheet feeding tray 21, the sheet feeding path RS from the sheet feeding trays 22 to 24, and the reverse conveyance path RR of the reverse conveyance unit 36 in the sheet conveyance unit 31. A registration sensor 286 is disposed in the center. Here, the registration sensor 286 is configured to convey the recording medium 100 or envelope 100E fed from each of the sheet feeding tray 21 and the sheet feeding trays 22 to 24, and the recording medium 100 or envelope fed again from the reverse conveying unit 36. It has a function of detecting the transport state of 100E and detecting whether or not there is overlapping transport from each transport path. As the resist sensor 286, for example, an optical sensor, a light transmission sensor, or the like can be used practically.

  In the print transport unit 32, a top edge sensor 287 is disposed between the registration roller 37 and the belt platen unit 65 on the transport path RC, and a top edge sensor 288 is disposed on the transport path RC in the belt platen unit 65. Has been. Both of the top edge sensors 287 and 288 have a function of detecting the conveyance state of the recording medium 100 or the envelope 100E sent from the registration roller 37 to the conveyance path RC. For example, an optical sensor can be practically used as the resist sensor 286.

  In the print conveyance unit 32, a floating detection sensor 289 is disposed between the conveyance path RC in the belt platen unit 65, here, between the top edge sensor 288 and the print head 61. The float detection sensor 289 has a function of detecting a float that contacts the print head 61, particularly on the leading end side in the transport direction of the recording medium 100 or the envelope 100E transported to the transport path RC. For example, an optical sensor, a mechanical contact sensor, or the like can be practically used as the floating detection sensor 289.

  In the ascending conveyance unit 33, an upper surface conveyance inlet sensor 291 is disposed at the first stage immediately after passing through the switching unit 325 of the conveyance route RV. The upper surface transport inlet sensor 291 has a function of detecting the transport state of the recording medium 100 or the envelope 100E transported from the transport route RC of the print transport unit 32 to the transport route RV of the ascending transport unit 33 through the switching unit 325. For example, an optical sensor can be practically used as the upper surface transfer entrance sensor 291.

  In the horizontal transport section 34, a flipper sensor 292 is disposed on the transport path RC. The flipper sensor 292 has a function of detecting the transport state of the recording medium 100 or envelope 100E transported on the transport path RC. For the flipper sensor 292, for example, an optical sensor can be practically used.

  In the paper discharge transport unit 35, a face-down paper discharge sensor 293 is disposed between the paper discharge roller 351 and the paper discharge tray in the paper discharge path RD2. The face-down paper discharge sensor 293 has a function of detecting the transport state of the recording medium 100 or envelope 100E transported to the paper discharge path RD2. For the face-down paper discharge sensor 293, for example, an optical sensor can be practically used.

  In the reverse conveyance unit 36, an upper surface conveyance outlet sensor 294 is disposed between the switching unit 361 and the conveyance roller 363 on the reverse conveyance route RR. The upper surface transport exit sensor 294 has a function of detecting the transport state of the recording medium 100 or the envelope 100E from the switching unit 361 to the transport roller 363 on the reverse transport path RR. A switchback sensor 295 is disposed between the conveyance roller 363 and the switchback unit 364 in the reverse conveyance path RR. The switchback sensor 295 has a function of detecting the transport state of the recording medium 100 or the envelope 100E transported between the transport roller 363 and the switchback unit 364 on the reverse transport path RR. A refeed sensor 296 is disposed between the switching unit 365 of the reverse transport path RR and the paper feed path RS of the print transport unit 32. The refeed sensor 296 has a function of detecting the transport state of the recording medium 100 or the envelope 100E transported from the switching unit 365 of the reverse transport path RR to the paper feed path RS. For example, an optical sensor can be practically used for each of the upper surface transport exit sensor 294, the switchback sensor 295, and the refeed sensor 296.

(6) Configuration of Detection Unit Further, in the paper feed conveyance unit 31 of the conveyance unit 3, various detection units are arranged in the paper feed path RS. In the image forming apparatus 1 according to the embodiment, a medium size detection unit 25, a medium thickness detection unit 26, and an envelope shape detection unit 27 are disposed in the paper feed path RS. The medium size detection unit 25 has a function of detecting the size of the recording medium 100, and is configured by, for example, a reflection sensor. The medium thickness detection unit 26 has a function of detecting the thickness of the recording medium 100, and is configured by, for example, a transmission sensor. The envelope shape detection unit 27 has a function of detecting the shape of the envelope 100E, and is configured by, for example, a contact image sensor (CIS) that can realize highly accurate detection and has a small size. Details of the detection methods of these various detection units will be described later.

  Note that the image forming apparatus 1 according to an embodiment is not limited to a system that performs printing in line units, and may be applied to a serial system that performs printing by scanning in the line direction.

[Basic printing operation of image forming apparatus]
The printing operation of the image forming apparatus 1 shown in FIGS. 1 and 2 is as follows. First, the unprinted recording medium 100 stored in any of the paper feed trays 21 to 24 of the paper feed unit 2 is one of the paper feed rollers 201 to 204 in the paper feed transport unit 31 of the transport unit 3. To the paper feed path RS. The recording medium 100 is transported to the registration roller 37 along the paper feed path RS using transport rollers 205 and 206. During the conveyance of the paper feed path RS, the size of the recording medium 100 is detected using the medium size detection unit 25, and the thickness of the recording medium 100 is detected using the medium thickness detection unit 26.

  When the envelope 100E is supplied from any of the paper feed trays 21 to 24, the shape of the envelope 100E is detected using the envelope shape detection unit 27 during the conveyance of the paper feed path RS, and the medium thickness detection unit 26 is detected. Is used to detect the thickness of each part of the envelope 100E (here, the main body 101 of the envelope 100E shown in FIGS. 3A to 3C, the flap 102, and the portion 1012 where the sheets are overlapped). Although illustration is omitted, a conveyance belt is used to detect the size, thickness, or shape of the recording medium 100 or the envelope 100E using the medium size detection unit 25, the medium thickness detection unit 26, and the envelope shape detection unit 27. The encoder pulse output from the medium conveyance amount detection unit (for example, constituted by an encoder) disposed on the driving roller 322 or the driving roller 322 can be used in combination.

  The registration roller 37 includes a pair of rollers arranged in a direction perpendicular to the sheet feeding path RS, and aligns and tilts the leading end (conveying direction leading end) of the conveyed recording medium 100 or envelope 100E. It has a function to correct lines. The recording medium 100 or envelope 100E conveyed to the registration roller 37 is temporarily stopped and then conveyed to the print conveyance unit 32 at a predetermined timing. That is, the registration roller 37 adjusts the delivery timing of the recording medium 100 or the envelope 100E to the print transport unit 32.

  In the print transport unit 32, the transport belt 321 is moved at a moving speed determined by the printing conditions, and the recording medium 100 or the envelope 100E is transported along the transport path RC according to the movement of the transport belt 321. When the recording medium 100 or the envelope 100E is conveyed on the plastic template 63, the print head 61 of the printing unit 6 ejects ink of each color, and color printing, monochrome printing, or gray scale printing is performed.

  The printed recording medium 100 or envelope 100E is transported along the transport path RC, and is transported to the paper discharge transport unit 38 using the switching unit 325 when discharged to the paper discharge unit 4. The recording medium 100 or the envelope 100 </ b> E conveyed to the paper discharge conveyance unit 38 is stored in the paper discharge tray of the paper discharge unit 4.

  When paper is discharged to the paper discharge unit 5, the printed recording medium 100 or the envelope 100 </ b> E is transported to the ascending transport unit 33 and then transported to the horizontal transport unit 34. Here, in the case of single-sided printing and discharging directly to the paper discharge unit 5, the paper is conveyed to the paper discharge conveyance unit 35 using the switching unit 361. The recording medium 100 or the envelope 100 </ b> E transported to the paper discharge transport unit 35 is stored in the paper discharge tray of the paper discharge unit 5.

  In the case of duplex printing, the recording medium 100 or the envelope 100E is conveyed from the horizontal conveyance unit 34 to the reverse conveyance unit 36 using the switching unit 361. In the reverse conveyance unit 36, the recording medium 100 or the envelope 100E is conveyed to the switchback unit 364 through the reverse conveyance path RR, and the recording medium 100 or the envelope 100E reverses the conveyance direction from the switchback unit 364 through the reverse switching unit 365 and The front and back are reversed and conveyed to the registration roller 37 again. As in the case of single-sided printing, the recording medium 100 is conveyed to the print conveying unit 32 with printing timing adjusted by the registration rollers 37, printed, and then lifted conveying unit 33, horizontal conveying unit 34, paper discharge The paper is sequentially transported to the transport unit 35 and stored in the paper discharge tray of the paper discharge unit 5.

  Such a printing operation of the image forming apparatus 1 is executed according to a printing schedule generated and managed in the control unit 8 (print schedule generation management unit 802) based on information included in the print job. Here, the print schedule is information included in a print job, for example, information such as setting information of the recording medium 100 or envelope 100E, information on the number of prints, setting information for color printing or monochrome printing, setting information for single-sided printing or double-sided printing, etc. On the basis of the above, schedules such as sheet feed start timing, registration roller 37 sending timing, printing unit 6 printing operation execution timing, paper discharge timing, and reversal timing are set. The management of the print schedule is performed in the control unit 8 (print schedule generation management unit 802) based on the detection results of various sensors arranged in the conveyance path of the conveyance unit 3.

[Type and structure of envelope]
There are various types of envelopes 100E used as the recording medium 100 described above. An envelope 100E shown in FIGS. 3A, 3B, and 3C is a long envelope 100E1 that is frequently used.

  The long envelope 100E1 includes a main body (envelope main body) 101 in which three sides of this rectangular shape are sealed, and a remaining part of the main body 101. And a flap (folding lid) 102 which is formed on one side and folded and then bound. Between the main body 101 and the flap 102 is a folded region 103 of the flap 102. The main body 101 has a portion in which one sheet (or a plurality of sheets including the inner bag) is folded into two, and portions 1011 and 1012 in which three sheets of glue are further stacked. The portion 1011 on which the sheets are overlapped is located at the center of the main body 101 in the case of center pasting, but may be located on one of two opposite sides of the three sides as side pasting. Further, the overlapped portion 1012 is located on one side (the ground with respect to the top) facing the flap 102 of the main body 101, has the same shape as the flap 102, and is glued in advance.

  The main body 101 and the flap 102 of the long envelope 100E1 shown in FIG. On the surface of the main body 101, a surface image 1013 that displays a destination such as an address, a company name, and a name is printed. The main body 101 and the flap 102 of the long envelope 100E1 shown in FIG. On the back side of the main body 101, a back side image 1014 displaying a sender such as an address, a company name, and a name is printed. The main body 101 and the flap 102 of the long envelope 100E1 shown in FIG.

  In the image forming apparatus 1 according to the embodiment, a part 1014A of the back image that does not overlap the folded flap 102 of the back image 1014 is printed on the back surface of the main body 101, and the flap 102 has a folded surface on the folded surface. Another part 1014B of the back image is printed. The other part 1014B of the back image is printed together with the printing of the front image 1013 on the surface of the main body 101. Further, the flap 102 is folded in advance on the main body 101, and the other part 1014B of the back image is printed together with the part 1014A of the back image printed on the back surface of the main body 101.

  Note that the envelope 100E that is the target of printing by the image forming apparatus 1 according to the embodiment is not limited to the long envelope 100E1. The envelope 100E includes at least a square envelope and a western envelope. Further, the envelope 100E includes, for example, an envelope with a window in which a window of a transparent film is provided on the surface side of the main body 101.

[System configuration of image forming apparatus]
(1) Schematic Configuration of Entire System As shown in FIG. 4, the control unit 8 of the image forming apparatus 1 according to an embodiment includes a control IC (control central processing unit) 80, an image information storage unit 81, and the like. And an envelope shape information acquisition unit 82. The control IC 80 includes an envelope shape determination unit 801, a print schedule generation management unit 802, and a conveyance acceleration / deceleration control unit 803. These control ICs 80 and the like of the control unit 8 are connected to each other, and the control IC 80 controls the image information storage unit 81 and the envelope shape information acquisition unit 82. The control unit 8 is connected to each of the interface unit 83 and the operation unit 84 and controls each of the interface unit 83 and the operation unit 84.

  The image information storage unit 81 of the control unit 8 includes an envelope information storage unit 810, an image information expansion unit 811, and an envelope image information expansion unit 812. The envelope information storage unit 810 further includes an envelope shape information storage unit 8101 and an envelope print image information storage unit 8102.

  The control IC 80 of the control unit 8 is further connected to each of a medium size detection unit 25, a medium thickness detection unit 26, and an envelope shape detection unit 27, which are various detection units disposed in the paper feeding and conveyance unit 31. Various sensors 281 to 283, 285 to 288, and 291 to 296 arranged in the conveyance path of the means 3 are connected to each other. Further, a drive circuit 220 is connected to the control IC 80, and the drive circuit 220 is connected to each of a paper feed transport unit drive source 210, a registration roller drive source 211, and a paper discharge transport unit drive source 212. The control IC 80 is connected to a belt drive source 230, a transport unit drive source 231, and a reverse transport unit drive source 232.

  Further, the printing unit 6 and the suction device 7 are connected to the control IC 80. The printing unit 6 further includes a head driving unit 610, a head gap adjusting unit 611, and an ink circulation unit 62. These head driving units 610 and the like are connected to the control IC 80.

(2) Configuration of Interface Unit The interface unit 83 is connected to an external terminal (not shown) installed outside the image forming apparatus 1 through a communication path such as a wired or wireless LAN, a telephone line, and a cable, and is transmitted from the external terminal. It has a function of receiving image information. The external terminal is, for example, a personal computer. The interface unit 83 has a function of receiving image information captured using a built-in scanner (not shown) and image information transmitted through a built-in facsimile. The interface unit 83 has a function of transmitting image information captured using the built-in scanner and information regarding the processing status of the print job to an external terminal or an external facsimile. Further, although not shown, the interface unit 83 includes a slot for a portable memory such as a USB memory or a card memory, and has a function of capturing image information stored in the portable memory.

(3) Configuration of Operation Unit Although the detailed configuration of the operation unit 84 is omitted, a power source for performing operations such as activation, stop, termination, printing, image capture, and image transmission / reception of the image forming apparatus 1 by the user. A switch, operation panel, etc. are provided. In the operation unit 84, printing conditions such as the type, size, color printing, monochrome printing, and gray scale printing of the recording medium 100 can be set during printing. Further, the operation unit 84 can set printing conditions such as the type, size, color printing, monochrome printing, and gray scale printing of the envelope 100E when printing the envelope 100E.

(4) Configuration of Image Information Storage Unit The image information storage unit 81 has a function of storing an image received or captured through the interface unit 83. The image information storage unit 81 stores image information to be printed on the recording medium 100. The envelope information storage unit 810 of the image information storage unit 81 stores image information printed on the envelope 100E.

  An envelope shape information storage unit 8101 of the envelope information storage unit 810 stores shape information (envelope information) of various envelopes 100E. Here, the shape information of the envelope 100E is information on at least the type and size. For example, the long envelope 100E1 shown in FIGS. 3A to 3C is JIS standardized, and the shape information includes the type “long 4” and the vertical dimension (vertical dimension) of the main body 101 of this type. ) Information on L “205 mm” and width dimension (width dimension) W “90 mm” is included. Further, in the image forming apparatus 1 according to the embodiment, the shape information includes information on the vertical dimension Lf of the flap 102, for example, “20 mm” and the vertical dimension Lg of the portion 1012 on which the sheets are overlapped, for example, “20 mm”. Here, each of the vertical dimension Lf of the flap 102 and the vertical dimension Lg of the overlapped portion 1012 coincides with the transport direction of the envelope 100E and has an equivalent dimension. The shape information of the envelope 100E is stored as information corresponding to each type.

  In the envelope print image information storage unit 8102 of the envelope information storage unit 810, a surface image 1013 printed on the surface of the main body 101 of the long envelope 100E1 shown in FIGS. Both pieces of image information of the back image 1014 printed on the back surface of the image are stored. The back image 1014 is image information that becomes one image when the flap 102 is closed, and a part of the back image 1014A printed on the back surface of the main body 101 and another part of the image printed on the front surface of the flap 102. And a back image 1014B.

  The image information expansion unit 811 stores print information generated based on image information to be printed on the recording medium 100 stored in the image information storage unit 81 (here, image information to be printed on the envelope 100E is excluded). In this image information expansion unit 811, the generation of print information is, for example, by generating print information by expanding the bitmap information in which pixel values are associated with each pixel of the image information stored in the image information storage unit 81. is there. The image information development unit 811 includes a circuit configuration and can generate print information internally. In one embodiment, the image information development unit 811 is a control IC 80 (specifically, a central processing unit (CPU) included therein). Is used to store print information generated based on a program stored in a storage device (not shown) in the control IC 80 or the image information expansion unit 811.

  The envelope image information expansion unit 812 basically has the same configuration and function as the image information expansion unit 811, and an image to be printed on the envelope 100E stored in the envelope print image information storage unit 8102 of the envelope information storage unit 810. Information, that is, envelope printing information generated based on the front image 1013 and the back image 1014 is stored. In the envelope image information development unit 812, the generation of the envelope print information is associated with the pixel value for each pixel of the image information stored in the envelope print image information storage unit 8102, for example, as in the generation of the print information described above. It is expanded into bitmap information and envelope printing information is generated. The envelope image information expansion unit 812 includes a circuit configuration and can also generate envelope print information inside. However, in one embodiment, the control IC 80 is used, and a storage device (not shown) inside the control IC 80 is used. Alternatively, envelope printing information generated based on a program stored in the envelope image information expansion unit 812 is stored.

  An image information storage unit 81 provided with an envelope information storage unit 810, an image information expansion unit 811 and an envelope image information expansion unit 812 is a storage device in one embodiment, and this storage device is constructed by a hard disk having a large capacity, for example. Yes. The storage device may use a single hard disk and appropriately assign each of the envelope information storage unit 810, the image information development unit 811 and the envelope image information development unit 812 as an area, or may assign each of the plurality of hard disks separately. Good. Further, the storage device may be replaced with a nonvolatile memory, or in the case of a plurality of hard disks, a part thereof may be replaced with a nonvolatile memory.

(5) Configuration of Detection Unit The medium size detection unit 25, the medium thickness detection unit 26, and the envelope shape detection unit 27 disposed in the paper feed conveyance unit 31 of the conveyance unit 3 illustrated in FIGS. The roller 206 is disposed upstream (upstream) and between the conveying rollers 206 and 205. These medium size detection unit 25, medium thickness detection unit 26, and envelope shape detection unit 27 are connected to a control IC 80 of the control unit 8 as shown in FIG.

  The medium size detecting unit 25 is mainly used for detecting the size of the recording medium 100. As shown in FIGS. 5A and 5B, the medium size detection unit 25 is configured to detect the difference in the amount of reflected light of the recording medium 100 conveyed to the paper feed path RS and the passage through the medium size detection unit 25. The length dimension of the recording medium 100 is detected based on the carry amount. In addition, when the sensors are arranged in a direction crossing the transport direction, the medium size detection unit 25 determines the amount of the recording medium 100 based on the difference in the amount of reflected light in the width direction of the recording medium 100 transported to the paper feed path RS. Detect width dimension. The difference in the amount of reflected light generates a detection signal as a difference in voltage, and this detection signal is output to the control IC 80.

  The envelope shape detector 27 is mainly used for detecting the shape of the envelope 100E. As shown in FIGS. 6A and 6B, the envelope shape detection unit 27 detects the difference in the amount of reflected light (or the amount of transmitted light) of the envelope 100E conveyed to the sheet feeding path RS, and detects the envelope 100E. Detect shape. A difference in reflected light amount (or transmitted light amount) generates a detection signal as a voltage difference, and this detection signal is output to the control IC 80.

  The medium thickness detector 26 is used to detect the thickness of the recording medium 100 and also to detect the thickness of each part of the envelope 100E. As shown in FIGS. 7A and 7B, the medium thickness detection unit 26 detects the amount of light transmitted through the recording medium 100 and the envelope 100E conveyed to the paper feed path RS to detect the recording medium 100 and the envelope 100E. Detect the thickness of the. In the envelope 100E, since the flap 102 is, for example, one sheet, the amount of transmitted light is large. The main body 101 is, for example, two sheets, so that the amount of transmitted light is medium. Since it is a sheet of paper, the amount of transmitted light is small. Accordingly, the medium thickness detection unit 26 can detect the thicknesses of the flap 102, the main body 101, and the portion 1012 where the sheets are stacked, based on the difference in the amount of transmitted light. The difference in transmitted light amount generates a detection signal as a difference in voltage, and this detection signal is output to the control IC 80. The detection result of the thickness of the envelope 100E using the medium thickness detection unit 26 is used as specific information of the length and part of the flap 102, the main body 101, and the portion 1012 where the sheets are overlapped. It is used as information for determining whether the leading end side in the transport direction of the envelope 100E transported to the transport path is the flap 102 or the main body 101 (portion 1012 on which sheets are stacked).

(6) Configuration of Envelope Shape Information Acquisition Unit The envelope shape information acquisition unit 82 shown in FIG. 4 described above acquires the shape information of the envelope 100E based on the output result of the medium thickness detection unit 26 and the output result of the envelope shape detection unit 27. To do. The shape information of the envelope 100E can also be acquired based on the output result of the medium size detection unit 25. In the envelope shape information acquisition unit 82, in particular, the size (length L) of the main body 101 of the envelope 100E and the size of the flap 102 (based on the output result of the medium thickness detection unit 26 and the output result of the medium transport amount detection unit 28) Information on the length (Lf) and the size (length Lg) of the overlapped portion 1012 and information on the direction of the envelope 100E in the conveyance direction (the flap 102 is the leading end in the conveyance direction or the portion 1012 where the sheets of the main body 101 overlap) It is possible to acquire and store information on the leading end side in the transport direction. Before starting printing of a large amount of envelopes 100E of the same type and shape, printing is not performed in advance, and the conveyance means 3 is used from the paper feed unit 2 to the paper discharge unit 4 or 5 through the printing unit 6. The sheet (or several sheets) of the envelope 100E is passed, and the shape information (envelope information) of the envelope 100E is acquired when the sheet is passed.

(7) Configuration of Driving System of Conveying Unit The driving circuit 220 is driven by the control unit 8 in detail based on a control signal from the control IC 80. The paper feeding / conveying unit driving source 210, the registration roller driving source 211, and the discharge conveying unit driving The source 212 is driven. The paper feeding / conveying section drive source 210 drives the paper feeding rollers 201 to 204 of the paper feeding / conveying section 31. The registration roller drive source 211 drives the registration roller 37. A paper discharge conveyance unit drive source 212 drives a paper discharge roller 381 of the paper discharge conveyance unit 38 and a paper discharge roller 351 of the paper discharge conveyance unit 35. For example, a DC motor is used for each of the paper feed conveyance unit driving source 210, the registration roller driving source 211, and the paper discharge conveyance unit driving source 212.

  Further, based on a control signal from the control IC 80, the belt drive source 230, the conveyance unit drive source 231, and the reverse conveyance unit drive source 232 are driven. The belt driving source 230 drives the driving roller 322, and the driving roller 322 drives the conveying belt 321. The transport unit drive source 231 drives the transport rollers 331 and 332 of the ascending transport unit 33, the transport rollers 341 of the horizontal transport unit 34, and the like. The reverse conveyance unit drive source 232 drives the conveyance rollers 362, 363, and 366 of the reverse conveyance unit 36. For example, a DC brushless motor is used for each of the belt drive source 230 and the conveyance unit drive source 231. For example, a stepping motor is used as the reverse conveyance unit drive source 232.

(8) Configuration of Envelope Shape Determination Unit of Control IC In the control unit 8, the envelope shape determination unit 801 of the control IC 80 acquires and stores envelope information acquired and stored in the envelope shape information acquisition unit 82 based on the detection results of various detection units. Is compared with the envelope information stored in the envelope shape information storage unit 8101 in advance as an existing value, and the shape of the envelope 100E that performs printing is determined. The determination of the shape of the envelope 100E includes the length L and width W of the main body 101 of the envelope 100E, the length Lf of the flap 102, the length Lg of the overlapped portion 1012, the direction of the envelope 100E in the transport direction, the flap This means that the envelope information relating to the open / close state of 102 is determined.

(9) Configuration of Print Schedule Generation Management Unit of Control IC The print schedule generation management unit 802 of the control IC 80 generates a print schedule based on information included in the print job of the recording medium 100 or the envelope 100E, and this print schedule Has a function of managing the respective implementation states of the transport operation, printing operation, and paper discharge operation of the recording medium 100 or envelope 100E according to the above. In the image forming apparatus 1, for example, the printing schedule generation timing is the start timing of the printing operation of the envelope 100E, the feeding timing of the envelope 100E from the paper feeding unit 2 to the conveying unit 3, the sending timing of the registration roller 37, the printing unit 6 Various timings such as the print timing, the discharge timing of the paper discharge unit 4 or 5 and the refeed timing of the reverse conveyance unit 36 are set on the time axis, and a schedule required for a series of printing from the start to the end of printing of the envelope 100E Is used to mean For the generation of the print schedule, for example, in the case of printing on the envelope 100E, information on the printing conditions such as the type, size, color printing, monochrome printing, and gray scale printing of the envelope 100E, and conveyance of the envelope 100E in the conveyance path of the conveyance unit 3 And at least information about the speed.

  In the print schedule generation management unit 802, various sensors are used for managing the execution state of the print schedule. For example, in the case of single-sided printing of the envelope 100E, whether or not the envelope 100E has passed through the paper feed path RS according to the schedule according to the printing schedule is determined based on the detection results of the conveyance sensors 281 to 283 and 285. It is determined based on the detection result of the top edge sensors 287 and 288 whether or not it has passed through the transport route RC as scheduled, and whether or not it has passed through the transport route RV as scheduled is determined based on the detection result of the upper surface transport inlet sensor 291. Whether or not the paper has passed through the transport route RC as planned is determined based on the detection result of the flipper sensor 292, and whether or not the paper passes through the paper discharge route RD2 as determined is determined based on the detection result of the face-down paper discharge sensor 293. The In the case of double-sided printing of the envelope 100E, whether or not the envelope 100E has passed each of the upper surface conveyance outlet sensor 294, the switchback sensor 295, and the refeed sensor 296 on the reverse conveyance route RR in accordance with the printing schedule in the conveyance unit 3. The determination is made based on the detection result, and the subsequent determination is made based on the detection result of each sensor as in the case of single-side printing. Based on these determinations, the print schedule generation management unit 802 can manage the execution state of the print schedule.

  In the image forming apparatus 1 according to the embodiment, the print schedule generation management unit 802 is configured as a dedicated circuit. However, the print schedule generation management unit 802 can be constructed by executing software using the control IC 80. it can.

(10) Configuration of Conveyance Acceleration / Deceleration Control Unit of Control IC The conveyance acceleration / deceleration control unit 803 of the control IC 80 conveys the envelope 100E detected using a conveyance sensor (here, the conveyance sensor 285 shown in FIG. 2). Based on the envelope information stored in the position and envelope information storage unit 810, the acceleration / deceleration of the conveyance speed of the envelope 100E using the conveyance roller 285 is controlled through the conveyance unit driving source 231, and the envelope 100E is transferred to the registration roller 37 during a certain conveyance time. It has the function to convey. Control of the acceleration / deceleration speed of the envelope 100E using the conveyance roller 285 is performed in the main body 101 except for the flap 102 of the envelope 100E and the portion 1012 where the sheets are overlapped. Envelope information stored in the envelope information storage unit 810 can be directly used to control the acceleration / deceleration of the conveyance speed of the envelope 100E. However, in the image forming apparatus 1 according to the embodiment, the envelope shape determining unit is finally used. Based on the envelope information determined using 801, the acceleration / deceleration control of the conveyance speed of the envelope 100E is performed.

  The conveyance sensor 285 is disposed in the paper feed conveyance unit 31, and the conveyance acceleration / deceleration control unit 803 controls the conveyance speed in the case of single-sided printing in which the envelope 100 </ b> E is conveyed from the paper supply unit 2 to the registration roller 37. The image forming apparatus 1 according to the embodiment further includes a re-feed sensor 296 and a transport roller 366 in the reverse transport unit 36, and the transport acceleration / deceleration control unit 803 performs the reverse transport of the reverse transport unit 36 as in the case of single-sided printing. Control of the conveyance speed when the envelope 100E is conveyed from the conveyance path RR to the registration roller 37 is performed. Here, since the transport speed control method in the case of double-sided printing is performed in the same manner as the transport speed control method in the case of single-sided printing, the transport speed control method in the case of single-sided printing will be described below. A description of the method for controlling the conveyance speed in the case of printing is omitted.

  The conveyance speed control of the conveyance acceleration / deceleration control unit 803 is performed as shown in FIG. In FIG. 8A, the horizontal axis indicates the registration roller 37 from the paper feed start (paper feed start time using the paper feed roller) of the recording medium 100 or envelope 100E stored in the paper feed unit 2, for example, the paper feed tray 22. The conveyance time (or conveyance period) of the recording medium 100 or envelope 100E until the arrival time is reached, and the vertical axis is the rotation speed (acceleration / deceleration) of the conveyance roller 206 (conveyance roller 366 in the case of double-sided printing).

The diagram a shows the recording medium 100 and the envelope conveyed from the paper feed tray 22 to the registration roller 37 at a constant reference conveyance speed V ₀ according to the print schedule generated by the print schedule generation management unit 802 (according to the theoretical value). The relationship between the conveyance time of 100E and the rotational speed of the conveyance roller 206 is shown. When the transport of the recording medium 100 or envelope 100E to the transport path RS from the paper feed tray 22 is started, after a predetermined time has elapsed, the conveying speed is accelerated from zero to the reference carrying speed V _0. When this reference transport speed V ₀ is maintained for a certain time and approaches the registration roller 37, the transport speed is reduced from the reference transport speed V ₀ to zero, and the leading end side in the transport direction of the recording medium 100 or envelope 100 E is transported to the registration roller 37. The After reaching the reference transportation speed V ₀ to the deceleration approaching the registration roller 37, the acceleration and deceleration of the conveying speed (the rotational speed of the conveying roller 206) without being carried out, there is no change in the conveying speed. The “conveyance sensor theoretical value” refers to the feeding start time of the recording medium 100 or the envelope 100E in the conveyance sensor 285 when the recording medium 100 or the envelope 100E is conveyed according to the print schedule without any delay or advance of the conveyance. Is the time (theoretical value) from when the conveyance sensor 285 detects the recording medium 100 or the envelope 100E.

The diagram b shows a recording medium that is transported from the paper feed tray 22 to the registration roller 37 when the transport time is advanced (transported quickly) with respect to the print schedule generated by the print schedule generation management unit 802. The relationship between the transport time of 100 and the rotation speed of the transport roller 206 is shown. When transport of the recording medium 100 from the paper feed tray 22 to the transport path RS is started, the transport speed is accelerated from zero to the reference transport speed V ₀ after a predetermined time has elapsed. After acceleration to the reference transport speed V ₀ , the recording medium 100 is detected by the transport sensor 285, and when the detection time is faster than the detection time according to the print schedule, the transport speed is slightly decelerated from the reference transport speed V ₀ , The reduced transport speed is maintained for a certain time. When approaching the registration roller 37, the decelerated conveyance speed is reduced to zero, and the leading end side of the recording medium 100 in the conveyance direction is conveyed to the registration roller 37. Although the conveyance speed is decelerated for a certain time from the reference conveyance speed V ₀ , the conveyance time from the start of feeding to the registration roller 37 is the same as the conveyance time according to the printing schedule. “Conveyance sensor actual measurement 1” is a time when the recording medium 100 is detected in a time that is faster than the print schedule due to progress of conveyance.

A diagram c shows a recording medium conveyed from the paper feed tray 22 to the registration roller 37 when the conveyance time is delayed (conveyed late) with respect to the print schedule generated in the print schedule generation management unit 802. The relationship between the transport time of 100 and the rotation speed of the transport roller 206 is shown. When transport of the recording medium 100 from the paper feed tray 22 to the transport path RS is started, the transport speed is accelerated from zero to the reference transport speed V ₀ after a predetermined time has elapsed. After acceleration to the reference transport speed V ₀ , the recording medium 100 is detected by the transport sensor 285, and when the detection time is slower than the detection time according to the print schedule, the transport speed is slightly accelerated from the reference transport speed V ₀ , The accelerated transport speed is maintained for a certain time. When approaching the registration roller 37, the accelerated conveyance speed is decelerated to zero, and the leading end side in the conveyance direction of the recording medium 100 is conveyed to the registration roller 37. Although the transport speed from the reference transport speed V ₀ is accelerated predetermined time, transport time from the sheet feed start until reaching the registration roller 37 is identical to the transport time in accordance print schedule. “Conveyance sensor measurement 2” is a time during which the recording medium 100 is detected in a time later than the print schedule due to a conveyance delay.

The diagram d relates to an embodiment of an envelope 100E that is transported from the paper feed tray 22 to the registration roller 37 when the transport time is advanced with respect to the print schedule generated by the print schedule generation management unit 802. The relationship between conveyance time and the rotational speed of the conveyance roller 206 is shown. When the transport of the envelope 100E is started the transport path RS from the paper feed tray 22, the conveying speed after a predetermined time has elapsed is accelerated from zero to the reference carrying speed V _0. After acceleration to the reference transport speed V ₀ , the envelope 100E is detected by the transport sensor 285 (detected in “transport sensor actual measurement 1”). If the detection time is fast relative to the detection time according to the print schedule, the transport speed is slightly decelerated from the reference transport speed V _0, the conveying speed reduced is maintained constant time.

  Since each area of the flap 102, the main body 101, and the overlapped portion 1012 can be specified from the envelope information obtained by the envelope information detecting means or the like, the deceleration of the envelope 100E is as shown in FIG. The conveyance roller 206 is used in the area (acceleration / deceleration area) of the main body 101 except for the area of the flap 102 or the portion 1012 where the sheets are overlapped. The thickness of the flap 102 and the portion 1012 where the sheets overlap is different from the thickness of the main body 102, and the strength of the waist changes for each part of the envelope 100E. Changes, which induces variations in the transport speed. Similarly, in the portion where the flap 102 is switched to the main body 101 and the portion where the main body 101 is switched to the overlapped portion 1012 is also caused in the conveyance speed variation due to the change in the thickness of the paper. In the image forming apparatus 1 according to an embodiment, an acceleration / deceleration region is set in the main body 101 that can ensure the longest and stable sheet thickness for a certain period in order to reduce such a variation in the conveyance speed. ing.

Since the conveyance speed is reduced in the acceleration / deceleration area of the main body 101 except for the area of the flap 102 or the part 1012 on which the paper is overlapped, the amount of waiting for the start of deceleration in the area of the flap 102 or the part 1012 on which the paper is overlapped, The deceleration is further increased slightly compared to the diagram b. When approaching the registration roller 37, the speed is reduced from the reduced transport speed to zero, and the leading end side in the transport direction of the envelope 100E is transported to the registration roller 37. Although the conveyance speed is decelerated for a certain time from the reference conveyance speed V ₀ , the conveyance time from the start of feeding to the registration roller 37 is the same as the conveyance time according to the printing schedule.

The diagram e relates to an embodiment of an envelope 100E that is transported from the paper feed tray 22 to the registration roller 37 when the transport time is delayed with respect to the print schedule generated by the print schedule generation management unit 802. The relationship between conveyance time and the rotational speed of the conveyance roller 206 is shown. When the transport of the envelope 100E is started the transport path RS from the paper feed tray 22, the conveying speed after a predetermined time has elapsed is accelerated from zero to the reference carrying speed V _0. After the acceleration to the reference transport speed V ₀ , the envelope 100E is detected by the transport sensor 285 (detected in “transport sensor actual measurement 2”). If the detection time is slower than the detection time according to the print schedule, the transport speed is slightly accelerated from the reference transport speed V _0, accelerated transport speed is maintained constant time. As in the case of deceleration, the envelope information obtained by the envelope information detecting means or the like can identify each area of the flap 102, the main body 101, and the overlapped portion 1012. Therefore, the acceleration of the envelope 100E is shown in FIG. As shown in C), the conveyance roller 206 is used in the area (acceleration / deceleration area) of the main body 101 except for the area of the flap 102 or the overlapped portion 1012 area.

Since the conveyance speed is accelerated in the area of the main body 101 (acceleration / deceleration area) except for the area of the flap 102 or the sheet overlapped portion 1012, the start of acceleration is waited in the area of the flap 102 or the sheet overlapped portion 1012. Accordingly, the acceleration is slightly larger than that of the diagram c. When approaching the registration roller 37, the accelerated conveyance speed is decelerated to zero, and the leading end side in the conveyance direction of the envelope 100E is conveyed to the registration roller 37. Although the transport speed from the reference transport speed V ₀ is accelerated predetermined time, transport time from the sheet feed start until reaching the registration roller 37 is identical to the transport time in accordance print schedule.

When there is no delay or proceed to transport the envelope 100E, similar to the diagram a, envelope 100E is maintained at reference transportation speed V ₀ without decelerating or accelerating. Here, a method of controlling the conveyance speed when the envelope 100E is conveyed with the flap 102 as the leading end side in the conveyance direction is described. Since the method for controlling the conveyance speed when the envelope 100E is conveyed with the overlapped sheet portion 1012 as the leading end side in the conveyance direction is performed in the same manner, the description of the control method is omitted because it overlaps.

The corrected conveyance speed V _{X that} is decelerated or accelerated from the reference conveyance speed V ₀ during the period from the start of paper feeding to the arrival at the registration roller 37 as shown in the above-described diagrams d and e is calculated using the following formula <1>.

Here, with reference to FIG. 8A, V _α1 is an average speed when accelerating from the reference transport speed (known number) V ₀ , and V _α2 is an average speed when decelerating from the reference transport speed V _0. . T _α1 is a time required for acceleration / deceleration, and T _α2 is a time required to stop from the corrected conveyance speed V _X. T _VX is the time during conveyance at the corrected conveyance speed V _X. L7r is the length of the conveyance speed correction section from the conveyance roller 285 to the registration roller 37 shown in FIG. The length L7r of the correction section is a known number, and the unit is mm or a number converted into an encoder pulse detected by the rotation of the transport unit drive source 231. Lf is the length in the conveyance direction of the flap 102 of the envelope 100E. The length Lf here is based on the length of the flap 102 regardless of whether the arrangement position of the conveyance roller 206 and the arrangement position of the conveyance sensor 285 are the same in the paper feed path RS. This is a value obtained by subtracting the distance between the position of the transport sensor 285 and the position of the transport sensor 285. In FIG. 8A, the second length Lf from the left is a period (distance) during which the transport roller 206 sandwiches the flap 102 of the envelope 100E. Further, the length Lf of the flap 102 is equivalent to the length Lg in the transport direction of the portion 1012 where the sheets are stacked.

Further, α is an acceleration. In FIG. 8A, α1 is an acceleration (a known number) during acceleration / deceleration from the reference conveyance speed V ₀ to the correction conveyance speed V _X , and α2 is stopped from the correction conveyance speed V _X. Acceleration (a known number). L _X is a value determined from the reference transport speed V ₀ and the difference time between the transport sensor theoretical value and the transport sensor actual measurement value (transport sensor actual measurement value 1 or 2). T _X is an actually measured delay amount with respect to the time of the theoretical value reaching the conveyance sensor 285.

The average speed V _α1 is expressed by the following formula <2>, the time T _α1 required for acceleration / deceleration is expressed by the following formula <3>, the time T _VX is expressed by the following formula <4>, and the average speed V _α2 is expressed by the following formula <5>. The required time T _α1 is calculated using the following formula <6>.

In the above formula <1>, the corrected conveyance speed V _X is drawn by the envelope 100E being conveyed according to the theoretical value of the conveyance sensor and reaching the registration roller 37 through the reference conveyance speed V ₀ as shown in FIG. 8B. And a diagram drawn by reaching the registration roller 37 through the reference conveyance speed V ₀ and the acceleration when the envelope 100E is detected in the area of the region surrounded by the diagram a (upward slanted region) and the conveyance sensor actual measurement value 2. The area surrounded by e is set to be the same as the area (upward slanted line area).

That is, a value (L7r−Lf) obtained by subtracting the length Lf at a constant speed of the flap 102 from the detection of the envelope 100E in the conveyance sensor actual measurement value 2 from the distance L7r (fixed value) from the conveyance sensor 206 to the registration roller 37 is Since it can be said that the rising conveyance distance (V _α1 · T _α1 + V _X · T _VX + V _α2 · T _α2 ) in the diagram e shown in FIG. 8B, the above formula <1> is obtained.

Here, by substituting the formulas <2> to <6> into the formula <1> and expanding the formula with the acceleration α = α1 = α2, the following formula <7> can be derived, and the corrected transport speed: V _X can be obtained. Note that, when the envelope 100E is transported earlier than the transport sensor theoretical value and is detected in the transport sensor actual measurement value 1, the corrected transport speed V _X can be calculated in the same manner.

The conveyance acceleration / deceleration control unit 803 calculates a corrected conveyance speed V _X , performs drive control of the conveyance unit drive source 231 based on the calculation result, and controls the acceleration / deceleration of the envelope 100 </ b> E using the conveyance roller 206. . The envelope 100E is transported with the flap 102 as the rear end side in the transport direction, and the flap 102 is thin (one sheet) from the thick (two sheets) portion of the main body 101 during transport along the transport path as shown in FIG. When the thickness of the envelope 100E is switched to a portion, the load applied to the transport roller 206 is reduced, which causes excessive feeding. Conversely, the envelope 100E is conveyed with the flap 102 as the leading end in the conveying direction, and a portion 1012 (three thick glued portions) in which sheets are stacked from the thin (two) portions of the main body 101 during conveyance on the conveyance path. When the thickness of the envelope 100E is switched, the load applied to the transport roller 206 becomes heavy, causing slippage between the transport roller 206 and the envelope 100E, resulting in insufficient feeding. The conveyance acceleration / deceleration control unit 803 controls the acceleration / deceleration of the conveyance speed in the region of the main body 101 having the longest contact with the conveyance roller 206 (the longest length L in the envelope 100E). In the region where the thickness of the envelope 100E is switched, acceleration / deceleration is controlled. Then, the conveyance acceleration / deceleration control unit 803 performs control for accelerating the conveyance speed of the envelope 100E when the conveyance time for conveying the envelope 100E to the registration roller 37 is less than a certain conveyance time (when a conveyance delay occurs), and the conveyance time Is controlled to decelerate the transport speed when the transport time exceeds a certain transport time (when transport progress occurs).

(11) Configuration of Printing Unit A head driving unit 610 of the printing unit 6 shown in FIG. 4 is connected to the control IC 80, and applies a voltage to be applied to a piezoelectric element (not shown) of the print head 61 based on a control signal of the control IC 80. Adjust and control ink ejection. The ink circulation unit 62 is connected to the control IC 80. For example, the control IC 80 controls the ink circulation pump of the ink circulation unit 62 to control the circulation of the ink, detects the temperature of the circulated ink, and controls the temperature regulator based on the detection result, thereby controlling the ink. Control the temperature.

  The head gap adjusting unit 611 of the printing unit 6 adjusts the head gap between the nozzle surface of the print head 61 and the surface of the recording medium 100 or the envelope 100E to an appropriate value based on the detection result of the medium thickness detecting unit 26. Particularly, in the envelope 100E, since the thickness of the main body 101, the flap 102, and the portion 1012 on which the sheets are stacked is different, the head gap is adjusted by the head gap adjusting unit 611 in order to ensure a constant head gap. . In the image forming apparatus 1 according to the embodiment, the details of the mechanism of the head gap adjustment unit 611 are omitted, but the belt platen unit 65 is moved in the vertical direction (a direction toward or away from the print head 61 using a drive source). ) To adjust the head gap.

(12) Configuration of Suction Device The suction device 7 is connected to the control IC 80, and the operation of the suction device 7 is controlled by the control of the control IC 80. Although not shown, the suction device 7 sucks the recording medium 100 and the envelope 100 </ b> E onto the surface of the transport belt 321 through the suction holes disposed in the plastic template 63 and the holes disposed in the transport belt 321. Accordingly, it is possible to prevent interference between the recording medium 100 or the envelope 100E and the print head 61, and it is possible to ensure a head gap appropriately.

[Control Method of Conveying Speed of Image Forming Apparatus]
As shown in FIG. 9, in the image forming apparatus 1 according to one embodiment, the method for controlling the conveyance speed from the recording medium 100 and the paper feed unit 2 of the envelope 100E to the registration roller 37 is as follows.

  First, in the image forming apparatus 1 according to the embodiment, it is determined whether or not the start signal of the transport unit driving source 231 is input from the control unit 8 (S1). When the start signal is not input, the process waits again until the start signal is input.

In step S1, when a start signal is input, the operation of the transport unit drive source 231 is started (S2). With the start of operation of the feeding section driving source 231, conveying rollers 206 perform sustainable rotation reference transportation speed V _0.

  It is determined whether or not a paper feed request signal has been issued (S3). If the paper feed request signal has not been issued, the process returns to the previous step. When the paper feed request signal is issued, the paper feed operation of the paper feed unit 2 is started (S4), and the recording medium 100 or the envelope 100E is fed from the paper feed unit 2 such as the paper feed tray 22 to the transport path RS.

  Subsequently, an encoder (not shown) disposed in the transport unit drive source 231 generates an encoder pulse with the rotation of the transport unit drive source 231 and starts counting the number of encoder pulses (S5). The conveyance time is measured by counting the number of encoder pulses.

  It is determined whether or not the recording medium 100 or the envelope 100E is detected by the transport sensor 285 (S6). When the recording medium 100 or the envelope 100E is not detected, the process returns to the previous step. When the recording medium 100 or the envelope 100E is detected, the counting of the encoder pulse number ends (S7).

  Based on the counted number of encoder pulses, the transport acceleration / deceleration control unit 803 calculates the slip amount when the paper feed roller 202 feeds, that is, the transport delay amount or advance amount during paper feed (S8). . Here, it is determined whether the recording medium 100 such as plain paper is fed and conveyed or whether the envelope 100E is fed and conveyed (S9).

  When the recording medium 100 is transported, the transport acceleration / deceleration control unit 803 performs drive control of the transport unit drive source 231 according to the slip amount, and records using the transport roller 206 according to the transport delay amount or advance amount. The acceleration / deceleration of the medium 100 is controlled (S15). Subsequently, the conveyance acceleration / deceleration control unit 803 calculates the stop position of the conveyance unit drive source 231 (S16). This is performed by calculating the number of encoder pulses from the detection of the recording medium 100 by the conveyance sensor 285 to the stop of driving of the conveyance unit drive source 231. It is determined whether the recording medium 100 is conveyed to the registration roller 37 and stopped at the stop position (S17). When it is determined that the recording medium 100 is stopped at the stop position, the operation of the transport unit drive source 231 is stopped (S13), and the transport of the recording medium 100 to the registration roller 37 is ended (S14).

  On the other hand, when the envelope 100E is conveyed in step S9, the conveyance is performed according to the slip information, the envelope information including the length L of the main body 101, the length Lf of the flap 102, and the length Lg of the portion 1012 on which the sheets are stacked. The acceleration / deceleration control unit 803 performs drive control of the conveyance unit drive source 231 and controls the acceleration / deceleration of the envelope 100E according to the conveyance delay amount or advance amount using the conveyance roller 206 (S10). Subsequently, the conveyance acceleration / deceleration control unit 803 calculates the stop position of the conveyance unit drive source 231 (S11). It is determined whether the envelope 100E is conveyed to the registration roller 37 and stopped at the stop position (S12). When it is determined that the envelope 100E is stopped at the stop position, the operation of the transport unit drive source 231 is stopped (S13), and the transport of the envelope 100E to the registration roller 37 is ended (S14).

[Features of Example]
In the image forming apparatus 1 according to the above-described embodiment, the conveyance acceleration / deceleration control unit 803 is based on the conveyance position of the envelope 100E detected using the conveyance sensor 285 and the envelope information stored in the envelope information storage unit 810. A constant conveyance speed (reference conveyance speed V ₀₎ using the conveyance roller 285 in the overlapped portion 1012 and the flap 102 having different conveyance conditions with respect to the conveyance conditions including the thickness of the main body 101 of the envelope 100E and the strength of the waist. ), And the conveyance speed acceleration / deceleration is controlled using the conveyance roller 285 in the main body 101 which is the reference of the conveyance condition and the conveyance condition does not change for the longest time. Therefore, the variation in the arrival timing of the envelope 100E to the registration roller 37 is varied. Can be reduced, and productivity can be stabilized. In the image forming apparatus 1, since it is possible to prevent the envelope 100E from being fed excessively, damage to the envelope 100E can be reduced.

  Furthermore, in the image forming apparatus 1 according to the embodiment, in the case of single-sided printing of the envelope 100E conveyed to the paper feed path RS and the double-sided printing of the envelope 100E conveyed to the reverse conveyance path RR. However, since the acceleration / deceleration of the conveyance speed can be controlled using the conveyance acceleration / deceleration control unit 803, the variation in the arrival timing of the envelope 100E to the registration roller 37 can be reduced, and the productivity is stabilized. be able to.

  Further, in the image forming apparatus 1 according to the embodiment, the envelope information detected by the envelope information detection unit (here, the envelope shape detection unit 27 and the medium thickness detection unit 26) and stored in the envelope shape information acquisition unit 802. Since the conveyance acceleration / deceleration control unit 803 controls the acceleration / deceleration of the envelope 100E based on the envelope information determined using the envelope shape determination unit 801 based on the information and the envelope information stored in the envelope information storage unit 810, it is accurate. Acceleration / deceleration control can be performed, and acceleration / deceleration control can be automatically performed without the user performing an operation corresponding to the conveyance direction of the envelope 100E.

  Furthermore, in the image forming apparatus 1 according to the embodiment, the envelope shape detection unit 27 is used to detect the length of the envelope 100E in the conveyance direction, and the medium thickness detection unit 26 is used to determine the thickness of the envelope 100E. Therefore, accurate envelope information can be detected, and as a result, appropriate acceleration / deceleration control of the envelope 100E can be performed.

  Further, in the image forming apparatus 1 according to the embodiment, the conveyance acceleration / deceleration control unit 803 is used to accelerate the conveyance speed of the envelope 100E when the conveyance time for conveying the envelope 100E to the registration roller 37 is less than a certain conveyance time. Since the control is performed to reduce the transport speed when the transport time exceeds a certain transport time, the variation in the arrival timing of the envelope 100E to the registration roller 37 can be reduced, and the productivity is stabilized. Can do.

  Furthermore, in the image forming apparatus 1 according to the embodiment, the conveyance acceleration / deceleration control unit 803 is not used to control the acceleration / deceleration of the conveyance speed in the flap 102 of the envelope 100E and the overlapped portion 1012 of the sheet. Since the acceleration / deceleration of the conveyance speed is not controlled in switching between the flap 102 of the 100E and the main body 101 and switching between the main body 101 and the portion 1012 where the sheets are overlapped, the change in the thickness of the envelope 100E and the strength of the envelope waist are not performed. The variation in the arrival timing of the envelope 100E to the registration roller can be reduced without causing the acceleration / deceleration control to follow the change, and the productivity can be stabilized.

(Other examples)
Although the present invention has been described by way of example as described above, the discussion and drawings that form part of this disclosure do not limit the invention. The present invention can be applied to various alternative embodiments, examples, and operational technologies. For example, the present invention is not limited to an ink jet printer, but can be applied to an image forming apparatus capable of printing an envelope, such as a laser printer.

  The present invention can be widely applied to image forming apparatuses that can reduce variations in the arrival timing of envelopes that change in the conveying direction in thickness and waist, and can stabilize productivity.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 100 ... Recording medium, 100E ... Envelope, 101 ... Main body, 102 ... Flap, 1013 ... Front image, 1014 ... Back image, 1014A ... Part of back image, 1014B ... Other part of back image , 103 ... folding area, 2 ... paper feed unit, 21 to 24 ... paper feed tray, 25 ... medium size detection unit, 26 ... medium thickness detection unit, 27 ... envelope shape detection unit, 28 ... recording medium conveyance amount detection unit, 286: Registration sensor, 287, 288 ... Top edge sensor, 291 ... Upper surface conveyance inlet sensor, 292 ... Flipper sensor, 293 ... Face down paper discharge sensor, 294 ... Upper surface conveyance outlet sensor, 295 ... Switchback sensor, 296 ... Refeed Paper sensor, 220... Drive circuit, 210... Paper feed conveyance unit drive source, 211 .. registration roller drive source, 212. ... belt drive source, 231 ... transport section drive source, 232 ... reverse transport section drive source, 281 to 283, 285 ... transport sensor, 3 ... transport means, 31 ... paper feed transport section, 32 ... print transport section, 33 ... ascending Conveying section 34 ... Horizontal conveying section 35 ... Discharge conveying section 36 ... Reversing conveying section 4,5 ... Discharging section 6 ... Printing section 61 ... Print head 610 ... Head gap driving section 611 ... Head Gap adjustment unit, 6101 ... Ink ejection timing adjustment unit, 62 ... Ink circulation unit, 63 ... Plastic template, 65 ... Belt platen unit, 66 ... Lowering mechanism, 7 ... Suction device, 8 ... Control unit, 80 ... Control IC, 801 ... Envelope shape determination means, 802 ... Print schedule generation management unit, 803 ... Conveyance acceleration / deceleration control unit, 81 ... Image information storage unit, 810 ... Envelope information storage unit, 8101 ... Envelope shape Distribution storage unit, 8102 ... Envelope Printing image information storage unit, 811 ... image information developing unit, 812 ... Envelope image information developing unit, 82 ... Envelope shape information acquisition unit, 83 ... interface unit, 84 ... operation part.

Claims (4)

A printing section for printing on the envelope;
A registration roller for adjusting a sending timing of the envelope conveyed to the conveyance path to the printing unit;
A transport roller disposed upstream of the transport direction of the registration roller in the transport path, and transports the envelope to the registration roller;
A transport unit drive source for driving the transport roller;
A transport sensor that is disposed in the transport path and detects a transport position of the envelope transported to the transport path;
An envelope information storage unit for storing envelope information including a size of a portion where the main body of the envelope, the flap and the paper are overlapped;
Transport position of the envelope is detected by said conveyance sensor, the transport roller on the basis of the envelope information stored in the transport position and the envelope information storage section of the envelope based on a preset the envelope of the print schedule The conveyance speed is controlled by controlling the acceleration / deceleration of the conveyance speed of the envelope used, and controlling the conveyance section drive source so that the envelope is conveyed to the registration roller during a certain conveyance time from the start of conveyance of the envelope to the registration roller. A speed control unit;
An image forming apparatus comprising: A printing section for printing on the envelope;
A registration roller for adjusting a sending timing of the envelope conveyed to the conveyance path to the printing unit;
A transport roller disposed upstream of the transport direction of the registration roller in the transport path, and transports the envelope to the registration roller;
A transport unit drive source for driving the transport roller;
A transport sensor that is disposed in the transport path and detects a transport position of the envelope transported to the transport path;
An envelope information storage unit for storing envelope information including a size of a portion where the main body of the envelope, the flap and the paper are overlapped;
Based on the envelope conveyance position detected using the conveyance sensor and the envelope information stored in the envelope information storage unit, the acceleration / deceleration of the envelope conveyance speed using the conveyance roller of the main body is controlled. A conveyance acceleration / deceleration control unit that controls the conveyance unit drive source so as to convey the envelope to the registration roller in a certain conveyance time from the start of conveyance of the envelope to the registration roller;
With
Further, disposed in the transport path, and envelopes information detection means for detecting the envelope information including the envelope of the body, the conveying direction of the information of the flap and the portion size as well as the envelope of the overlaid sheets,
An envelope shape information acquisition unit for storing the envelope information detected using the envelope information detection means;
Based on the envelope information stored in the envelope shape information acquisition unit and the envelope information stored in the envelope information storage unit, the size of the envelope body, the flap and the overlapped portion of the paper, and the conveyance direction of the envelope are determined. Envelope shape judging means for judging,
The transport acceleration / deceleration control unit is configured to control the envelope transported in the transport path based on the size of the envelope main body, the flap and the overlapped portion of the paper determined by the envelope shape determining means, and the transport direction of the envelope. An image forming apparatus that controls acceleration / deceleration.   The conveyance acceleration / deceleration control unit performs control for accelerating the conveyance speed of the envelope when the conveyance time for conveying the envelope to the registration roller is less than the certain conveyance time, and the conveyance time exceeds the certain conveyance time. 3. The image forming apparatus according to claim 1, wherein control is performed to reduce the conveyance speed. The conveyance acceleration / deceleration control unit does not control the acceleration / deceleration of the conveyance speed at the overlapped portion of the flap and the paper of the envelope, and switches between the flap and the main body of the envelope, and the main body and the paper. 4. The image forming apparatus according to claim 1, wherein the control of acceleration / deceleration of the conveyance speed is not performed in switching between the overlapped portions. 5.