JP2012218835A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing noise by properly adjusting the assist speed of a conveying roller when printing envelopes, and shortening a printing time.SOLUTION: The image forming apparatus 1 includes a register roller for adjusting the feed-out timing of envelopes to be conveyed to a conveying passage to a printing unit 6, a register roller drive source 211 for driving the register roller, a conveying roller which is arranged on the first stage of the register roller of the conveying passage to feed out the envelopes to the register roller, a conveying unit drive source 321 for driving the conveying roller, an envelope information detection means which is arranged in the conveying passage to detect envelope information, and an assist speed control means for adjusting the conveying speed of the conveying roller for conveying the envelopes to the register roller based on envelope information.

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of printing on an envelope.

  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 order to support printing of recording media of various sizes and types (especially paper quality), the printer arranges registration rollers in the conveyance path of the recording media and uses this registration rollers to adjust the sending timing to the printing unit. It has a mechanism to do. The recording medium fed from the paper feed unit is transported along the transport path and is temporarily held by the registration rollers. By temporarily holding, the skew correction of the recording medium is performed, and slack can be generated in the recording medium. This recording medium is sent out by driving the registration roller at the printing timing in the printing unit.

  As described above, there are various sizes and types of recording media. In addition, when a plurality of sheet feeding trays of the sheet feeding unit are provided, there are a plurality of conveying paths from the sheet feeding tray to the registration rollers, and the conveying distance and the number of bendings of the recording medium during the conveyance are different. . That is, in the conveyance path from the paper feeding unit to the registration roller, the recording medium conveyance conditions differ depending on the size and the like.

  When the conveyance speed (sending speed) of the recording medium of the registration roller is higher than the conveyance speed of the conveyance roller upstream of the registration roller (upstream in the conveyance direction), the recording medium remains in a state where the conveyance roller sandwiches the recording medium. The leading end in the transport direction is pulled by the registration roller. So-called back tension occurs. When the slack of the recording medium generated in the registration roller for the purpose of correcting skew feeding and adjusting the feeding timing is eliminated by the start of driving of the registration roller, noise is generated when the recording medium is stretched all at once. In addition to noise, the occurrence of back tension is a factor that induces a conveyance timing delay of the recording medium, a printing position shift, a conveyance failure such as a jam, and hinders an increase in printing time as a whole.

  In Patent Document 1 below, it is possible to form moderate slack on various types of printing paper, to prevent noise when slack is eliminated, and to secure paper spacing in the transport path to increase printing speed. A paper feeding mechanism and a paper feeding method of a printing apparatus that can be used are disclosed. The paper feed mechanism includes an assist control unit, and the assist control unit controls the operation speed or the operation acceleration of the paper feed unit.

JP 2010-215389 A

  However, in the paper feeding mechanism and paper feeding method of the printing apparatus disclosed in the above-mentioned 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. When the flap is folded back (when the flap is closed), three sheets are stacked and the thickness of the flap is increased.

  When the envelope is conveyed from the sheet feeding unit to the registration roller along the conveyance path in a state where the flap of the envelope is the leading end side in the conveyance direction, the envelope is loosened in the registration roller. Since the flap is a sheet of paper and the flap is weak (elasticity is weak or sticky), the envelope is easily loosened. The slackening causes a repulsive force due to the waist on the transport roller, but this repulsive force is small because the waist is weak, and slippage associated with transporting the transport roller envelope is small, so assist when transporting the transport roller envelope Increases speed.

  On the contrary, when the envelope is conveyed from the sheet feeding unit to the registration roller along the conveyance path with the flap of the envelope as the rear end side in the conveyance direction and the main body as the front end side in the conveyance direction, the looseness of the envelope in the registration roller is reduced. The main body has a plurality of sheets folded and glued to the portion, and since the main body is strong, the envelope is less likely to sag. The repulsive force generated by the occurrence of the slack is large because the back is strong, and the slip accompanying the conveyance of the envelope of the conveyance roller is large, and therefore the assist speed when conveying the envelope of the conveyance roller is slow.

  In this way, the thickness of the envelope is partially different, and the assist speed of the transport roller varies depending on the direction of the transport direction when printing the envelope. Further, even if the envelope flap is transported on the leading end side in the transport direction, the assist speed varies depending on whether the flap is opened or the flap is closed. In the above-mentioned Patent Document 1, there is no intention to print envelopes, and in envelope printing, printing is performed while preventing noise and preventing conveyance failure such as delay in conveyance timing, misalignment of printing position, jam and the like. Speeding up time could not be realized.

  The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide an image forming apparatus capable of appropriately adjusting the assist speed of the conveyance roller in envelope printing, preventing noise, and increasing the printing time.

  In order to solve the above-described problems, a first feature of the present invention is that, in the image forming apparatus, a registration roller that adjusts a sending timing of an envelope conveyed to a conveyance path to a printing unit, and a registration roller that drives the registration roller. A roller driving source, a conveyance roller disposed before the registration roller in the conveyance path, and sending an envelope to the registration roller; a conveyance unit driving source for driving the conveyance roller; and a conveyance path disposed in the conveyance path, And envelope information detection means for detecting envelope information including flap opening / closing information of the envelope, and assist speed control means for adjusting the conveyance speed (especially assist speed) of the conveyance roller for conveying the envelope to the registration roller based on the envelope information With. Here, the assist speed control means preferably adjusts the transport speed of the transport roller that generates slack in the envelope transported between the registration roller and the transport roller based on the envelope information.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the envelope information detection unit further includes information on any one of an envelope body size, an envelope flap size, and an envelope paper type. It is to detect envelope information.

  According to a third feature of the present invention, in the image forming apparatus according to the first feature or the second feature, the envelope information detection means includes an envelope shape detection unit that detects the size of the envelope body and the size of the flap, and the body And a medium thickness detector for detecting the thickness of the flap and the thickness of the flap.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first to third features, the assist speed control unit is configured to convey the conveyance roller based on the envelope information detected using the envelope information detection unit. An assist speed calculation unit that calculates a speed and an assist speed adjustment unit that adjusts the drive speed of the transport roller of the transport unit drive source based on the transport speed calculated by the assist speed calculation unit.

  A fifth feature of the present invention is the image forming apparatus according to the first feature to the fourth feature, wherein the assist speed control means is the envelope information detecting means, wherein the envelope flap is in the open state and the flap is in the transport direction of the envelope. In contrast to the conveyance speed when the leading edge side is detected, the envelope speed is controlled to be fast and the conveyance speed when the flap is detected to be the trailing edge side in the conveyance direction of the envelope.

  According to the image forming apparatus of the first aspect of the present invention, the envelope information of the envelope is detected using the envelope information detection unit, and the conveyance using the conveyance unit drive source is performed based on the envelope information using the assist speed control unit. The conveyance speed (assist speed) of the roller can be adjusted. Therefore, since the conveyance speed of the conveyance roller can be appropriately adjusted in envelope printing, the generation of back tension can be eliminated and noise can be prevented. Furthermore, it is possible to prevent a conveyance failure such as a conveyance timing delay, a printing position shift, and a jam, so that the printing time can be increased.

  According to the image forming apparatus according to the second feature of the present invention, in addition to the effects obtained in the image forming device according to the first feature, the size of the main body of the envelope, the flap of the envelope using the envelope information detecting means Since the envelope information having each information of the size, the conveyance direction of the envelope, and the opening / closing of the flap of the envelope can be detected, the conveyance speed can be appropriately adjusted according to the conveyance form of the envelope.

  According to the image forming apparatus relating to the third feature of the present invention, in addition to the effect obtained in the image forming device relating to the first feature or the second feature, the envelope shape detecting unit of the envelope information detecting means is used. The envelope body size and flap size are detected by detecting the envelope body size and flap size, and detecting the body thickness and flap thickness using the media thickness detector. Envelope information can be obtained, and envelope information of the envelope conveyance direction and envelope flap opening and closing can be extracted.

  According to the image forming apparatus relating to the fourth feature of the present invention, in addition to the effects obtained in the image forming device relating to the first feature to the third feature, the envelope information detected using the envelope information detecting means. Based on the above, the transport speed of the transport roller is calculated using the assist speed calculation unit of the assist speed control means, and based on the calculated transport speed, the drive speed of the transport roller of the transport unit drive source is calculated using the assist speed adjustment unit. Therefore, the conveyance speed can be appropriately adjusted according to the conveyance form of the envelope.

  According to the image forming apparatus of the fifth feature of the present invention, using the assist speed control means, the envelope information detecting means detects that the envelope flap is in the open state and the flap is at the leading end side in the envelope conveyance direction. The transport speed when the envelope flap is closed and when the flap is detected to be the rear end side in the transport direction of the envelope can be controlled quickly, so according to the transport mode of the envelope The conveyance speed can be adjusted appropriately.

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 an image forming apparatus according to an embodiment, (B) is a diagram illustrating a detection result of the thickness of the envelope in the medium thickness detection unit, and (C) is a medium conveyance amount detection unit. It is a figure which shows the signal waveform output from. (A) is a schematic cross-sectional view showing a state of conveyance of an envelope with a flap in a paper feeding / conveying section as a front end side in the conveyance direction in the image forming apparatus according to the embodiment, and (B) conveys a main body in the paper feeding / conveying section FIG. 4C is a schematic cross-sectional view showing a state of conveyance of the envelope on the leading end side in the direction, and FIG. (A) is a schematic cross-sectional view showing an envelope conveyance state in which the flaps in the sheet feeding conveyance unit and the reverse conveyance unit are on the leading side in the conveyance direction in the image forming apparatus according to the embodiment, and (B) is a sheet feeding conveyance unit. And the typical sectional view which shows the conveyance state of the envelope which makes the main body in a reverse conveyance part the conveyance direction front end side, (C) is a figure which shows the relationship between the speed of various rollers, and conveyance time. 6 is a flowchart illustrating an envelope printing method of the image forming apparatus according to an 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]
As shown in FIG. 1, an image forming apparatus 1 according to an embodiment includes a sheet feeding unit 2 that supplies a recording medium 100, a conveying unit 3 that conveys the recording medium 100 supplied from the sheet feeding unit 2, The printing unit 6 that performs printing on the recording medium 100 that has been transported by the transporting unit 3, the paper discharge units 4 and 5 that discharge the recording medium 100 on which printing has been performed, and controls the operations of these units. And a control unit 8.

  The paper feed unit 2 includes paper feed trays 21 to 24, although not limited to the number and form of arrangement. 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.

  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.

  The transport means (transport mechanism) 3 includes a paper feed transport unit 31, a print transport unit 32, a lift transport unit 33, a horizontal transport unit 34, a paper discharge transport unit 35, and a reverse transport unit 36. .

  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.

  The print transport unit 32 faces the transport path RC for transporting 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 print head 61 of the printing unit 6. And a driving belt 322 for driving the conveying belt 321.

  As shown in FIG. 1, 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 RD1. 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 conveyance unit 36 is switched again from the switchback unit 364 for reversing the direction of the recording medium 100 in the conveyance direction and from the switching unit 361 at the end of the horizontal conveyance 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 reverse conveying unit 36 reverses the recording medium 100 that has been printed on one side, and conveys the recording medium 100 to the print conveying unit 32 during double-sided printing.

  As shown in FIG. 1, in the printing unit 6, print heads 61 are arranged on the transport path 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). is 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. .

  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 4 after printing.

  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 conveyed and printed by the printing unit 6 to the plastic template 63 through a hole (not shown) of the conveying 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.

  Further, in the sheet feeding / conveying section 31 of the conveying means 3, various detection units are arranged in the sheet feeding 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.

  A recording medium conveyance amount detection unit 28 is disposed on the conveyance belt 321 of the printing unit 6 or the driving roller 322 that drives the printing belt 6. In the image forming apparatus 1 according to the embodiment, the recording medium conveyance amount detection unit 28 uses an encoder that generates a regular pulse (encoder pulse) according to the movement amount of the conveyance belt 321 or the rotation amount of the driving roller 322. It is configured. The generated pulse is used to detect the size of the recording medium 100, particularly the length in the transport direction. When the envelope 100E is used as the recording medium 100, the pulse is the size of the envelope 100E, particularly the length in the transport direction, the length of the main body (reference numeral 101 shown in FIGS. 3A and 3B). Length L) and the length of the flap (length Lf of reference numeral 102 shown in the figure) are used for detection.

  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. Further, 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. As will be described later, each of the size of the recording medium 100 using the medium size detection unit 25, the thickness of the recording medium 100 using the medium thickness detection unit 26, and the shape of the envelope 100E using the envelope shape detection unit 27 are detected. The encoder pulse output from the medium conveyance amount detection unit 28 disposed on the conveyance belt 321 or the driving roller 322 is used together.

  The registration roller 37 includes a pair of rollers arranged in a direction perpendicular to the sheet feeding path RS, and has a function of performing alignment, skew correction, and the like of the leading end of the transported recording medium 100 in the supply direction. . The recording medium 100 (or envelope 100E) conveyed to the registration roller 37 temporarily stops here, and is conveyed to the print conveyance unit 32 at a predetermined timing. That is, the registration roller 37 adjusts the sending timing of the recording medium 100 to the print conveyance 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 is transported along the transport path RC according to the movement of the transport belt 321. With the movement of the conveyance belt 321 or the rotation of the driving roller 322, the medium conveyance amount detection unit 28 outputs regular encoder pulses. When the recording medium 100 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 is transported along the transport path RC, and is transported to the paper discharge transport unit 38 using the switching unit 325 when being discharged to the paper discharge unit 4. The recording medium 100 conveyed to the paper discharge conveyance unit 38 is stored in a paper discharge tray of the paper discharge unit 4.

  When paper is discharged to the paper discharge unit 5, the printed recording medium 100 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 transported to the paper discharge transport unit 35 is stored in a paper discharge tray of the paper discharge unit 5. In the case of duplex printing, the recording medium 100 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 is conveyed to the switchback unit 364 through the reverse conveyance path RR, and the recording medium 100 is conveyed from the switchback unit 364 to the registration roller 37 again with the conveyance direction reversed and the front and back reversed. Is done. 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 transport unit 35 is sequentially transported and stored in a paper discharge tray of the paper discharge unit 5.

[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. The main body 101 includes a portion where one sheet (or a plurality of sheets including an inner bag) is folded into two, and portions 1011 and 1012 where three sheets of glue are further overlapped. 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]
As shown in FIG. 4, the control unit 8 of the image forming apparatus 1 according to the embodiment includes a control IC (control central processing unit) 80, an image information storage unit 81, an envelope shape information acquisition unit 82, and the like. It has. The control IC 80 further includes an envelope shape determination unit 801, an assist speed calculation unit 802, and an assist speed adjustment unit 803. These control ICs 80 of the control unit 8 are connected to each other, and the control IC 80 controls each of 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 further includes a medium size detection unit 25, a medium thickness detection unit 26, an envelope shape detection unit 27, and a medium conveyance amount detection unit 28, which are various detection units disposed in the paper feed conveyance unit 31. Each of which is connected. 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, and these head driving units 610 and the like are connected to the control IC 80.

  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 has a function of receiving image information transmitted from the external terminal. Have. 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.

  Although the detailed configuration of the operation unit 84 is omitted, a power switch, an operation panel, and the like that perform operations such as activation, stop, termination, printing, image capture, and image transmission / reception of the image forming apparatus 1 by the user are arranged. Has been established. 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.

  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.

  The envelope shape information storage unit 8101 of the envelope information storage unit 810 stores shape 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”. 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 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 inside. In one embodiment, the image information development unit 811 uses a control IC 80, and a storage device or an image (not shown) inside the control IC 80 is used. Print information generated based on a program stored in the information expansion unit 811 is stored.

  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.

  The medium size detection unit 25, the medium thickness detection unit 26, the envelope shape detection unit 27, and the medium conveyance amount detection unit 28 disposed in the paper feed conveyance unit 31 of the conveyance unit 3 are connected to the control IC 80 of the control unit 8. Yes.

  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 detection unit 26 is used for detecting the thickness of the recording medium 100 and also for detecting the thickness 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 one sheet, the amount of transmitted light is large, and since the main body 101 is two sheets, the amount of transmitted light is medium, and the overlapped portion 1012 has three sheets. Therefore, 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.

  For example, an encoder is used for the medium conveyance amount detection unit 28, and the medium conveyance amount detection unit 28 is arranged at regular intervals according to the movement of the conveyance belt 321 or the rotation of the driving roller 322 as shown in FIG. An encoder pulse having a pulse waveform having (same pitch) is generated. Here, the encoder pulse output from the medium conveyance amount detection unit 28 is used together with the detection of the thickness of the envelope 100E of the medium thickness detection unit 26, and the time zone of the change in the thickness of the envelope 100E in the conveyance direction of the envelope 100E is encoded. It is measured using the number of pulses. The detection output of the medium conveyance amount detection unit 28 is used in combination with at least one of the detection output of the medium size detection unit 25 and the detection output of the envelope shape detection unit 27 to detect the size of the recording medium 100 in the conveyance direction. Alternatively, it can be used for detecting the shape of the envelope 100E.

  The envelope shape information acquisition unit 82 shown in FIG. 4 acquires the shape information of the envelope 100E based on the output result of the medium thickness detection unit 26, the output result of the envelope shape detection unit 27, and the output result of the medium conveyance amount detection unit 28. To do. The shape information of the envelope 100E can 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 information on the direction of the envelope 100E in the transport direction (information on whether the flap 102 is on the front end side or the rear end side in the transport direction) can be acquired and stored. 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) envelopes 100E are passed, and the shape information of the envelope 100E is acquired at the time of passing.

  The drive circuit 220 drives the paper feed / conveyance unit drive source 210, the registration roller drive source 211, and the paper discharge / conveyance unit drive source 212 based on a control signal from the control unit 8, specifically the control IC 80. 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 341 and 342 of the ascending transport unit 33, the transport rollers 351 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.

  In the control unit 8, the envelope shape determining means 801 of the control IC 80 preliminarily stores the envelope information acquired and stored in the envelope shape information acquisition unit 82 based on the detection results of the various detection units and the existing value in the envelope shape information storage unit 8101. The stored envelope information is compared, and the shape of the envelope 100E that performs printing is determined. With the determination of the shape of the envelope 100E, the envelope information regarding the length L, the width W of the main body 101 of the envelope 100E, the length Lf of the flap 102, the direction of the envelope 100E in the transport direction, the open / close state of the flap 102, etc. is determined. It means that.

  The assist speed calculation unit 802 and the assist speed adjustment unit 803 of the control IC 80, the registration roller 37, the registration roller drive source 211, the transport rollers 206 and 366, the paper feed transport unit drive source 210, and the envelope information detection unit are assist speed control units. Build up. The assist speed control means has a function of adjusting the assist speed (the transport speed according to the claims) of the transport rollers 206 and 366 using the paper feed transport unit drive source 210 based on the envelope information. Here, the envelope information detecting means is the envelope information detecting means according to the claims and features of the present invention. The assist speed control means is the assist speed control means according to the claims and features of the present invention.

  In the image forming apparatus 1 according to the embodiment, the envelope information detection unit includes at least the size of the envelope 100E (particularly, the length L of the main body 101 and the length Lf of the flap 102) and the conveyance direction of the envelope 100E. And a configuration necessary for detecting various types of envelope information of the opening / closing state of the flap 102 of the envelope 100E. Here, at least a medium thickness detection unit 26 that detects the thickness of each part of the envelope 100E, a medium conveyance amount detection unit 28 that detects the length of the envelope 100E in the conveyance direction, and envelope shape information that stores envelope information of existing values A storage unit 8101, an envelope shape information acquisition unit 82 that acquires and stores envelope information, and an envelope shape determination unit 801 that determines envelope information are provided, and an envelope information detection unit is constructed. In the envelope information detecting means, in order to adjust the assist speed of the transport rollers 206 and 366, envelope information including at least the transport direction information of the envelope 100E and the opening / closing information of the flap 102 is detected.

  The assist speed calculation unit 802 of the assist speed control unit calculates the assist speed of the transport roller 206 or 366 based on the envelope information detected using the envelope information detection unit. Here, the assist speed is constant even after the sending timing of the envelope 100E of the registration roller 37 by generating a slack in the envelope 100E conveyed between the registration roller 37 and the conveyance roller 206 or 366 in the paper feed path RS. It is used in the sense of the conveyance speed of the conveyance roller 206 or 366 for continuing the slack.

  In FIG. 8A, the paper is fed from the paper feed tray 21 of the paper feed unit 2 to the paper feed path RS of the paper feed transport unit 31 with the flap 102 of the envelope 100E as the leading end in the transport direction and with the flap 102 open. In the registration roller 37, a state in which a slack is generated on the front end side in the conveyance direction of the envelope 100E is shown. In this case, the leading edge of the flap 102 of the envelope 100E comes into contact with the registration roller 37 and the conveyance of the leading edge portion is temporarily stopped. However, the conveyance roller (primary paper feed roller) 206 conveys the rear end of the envelope 100E in the conveyance direction. Since it is continuing, the envelope 100E is loosened between the registration roller 37 and the conveying roller 206. Since the flap 102 has a small number of sheets folded with respect to the main body 101 and the mechanical rigidity (strength of waist) of the envelope 100E is weak, the flap 102 is not loosened toward the conveying roller 206 (opposite to the conveying direction). The repulsive force F1 due to the reaction is small. Accordingly, the slip between the envelope 100E and the transport roller 206 is small, and the assist speed of the envelope 100E of the transport roller 206 is increased.

  FIG. 8C shows the relationship between the rotation speed (assist speed) of various rollers and the conveyance time. The vertical axis represents the rotation speed of the roller, and the horizontal axis represents the conveyance time. The registration roller 37 sends the temporarily stopped envelope 100E to the print conveyance unit 32 at a predetermined sending timing. Therefore, the conveyance speed (acceleration) of the registration roller 37 is set to the conveyance speed (acceleration) of the conveyance roller 206 in order to absorb the slack generated while conveying the envelope 100E that is continuously conveyed using the conveyance roller 206. The registration roller 37 reaches a constant conveying speed at a stretch. The constant conveyance speed is continued until the registration roller 37 has sent the envelope 100E to the print conveyance unit 32. As described above, in the conveyance of the envelope 100E with the flap 102 shown in FIG. 8A as the leading end in the conveyance direction, the assist speed of the conveyance roller 206 is increased due to the repulsive force F1, so the assist speed calculation unit 802 Calculates a correction value for slowing down the assist speed of the transport roller 206 and adjusting it to an appropriate assist speed. The appropriate assist speed is a speed at which the transport speed of the envelope 100E is constant regardless of the transport direction of the envelope 100E.

  On the other hand, in FIG. 8B, the flap 102 of the envelope 100E is placed on the rear end side in the transport direction from the paper feed tray 21 of the paper feed unit 2 to the paper feed path RS of the paper feed transport unit 31 (the sheets of the main body 101 are overlapped). A state is shown in which the sheet is fed with the flap 102 in the open state and the registration roller 37 generates a slack on the front end side in the transport direction of the envelope 100E. In this case, the tip of the portion 1012 of the main body 101 of the envelope 100E that is in contact with the registration roller 37 comes into contact with the tip 100 to temporarily stop the conveyance, but the conveyance roller 206 is conveyed on the rear end side in the conveyance direction of the envelope 100E. Therefore, the envelope 100E is loosened between the registration roller 37 and the conveying roller 206. Since the main body 101 has a large number of sheets folded with respect to the flap 102 and the mechanical rigidity of the looseness of the envelope 100E is strong, the repulsive force F2 due to the recoil of the slack to the conveying roller 206 side is large. Therefore, the slip between the envelope 100E and the transport roller 206 is large, and the assist speed of the envelope 100E of the transport roller 206 is slow.

  8C, as described above, in the conveyance of the envelope 100E with the main body 101 shown in FIG. 8B as the leading end in the conveyance direction, the assist speed of the conveyance roller 206 is slow due to the repulsive force F2. Therefore, the assist speed calculation unit 802 calculates the correction value for increasing the assist speed of the transport roller 206 and adjusting the assist speed to an appropriate assist speed. When the envelope 100E is transported with the flap 102 of the envelope 100E at the leading end in the transport direction and the flap 102 closed, the assist speed calculation unit 802 increases the assist speed of the transport roller 206 and adjusts it to an appropriate assist speed. The correction value to be calculated is calculated.

  By adjusting the conveyance roller 206 to an appropriate assist speed, it is possible to reduce the generation of noise that occurs when loosening is stretched all at once when the envelope 100E of the registration roller 37 is sent out. Furthermore, since the occurrence of back tension on the envelope 100E generated at this time can be reduced, there are no factors that cause a conveyance failure such as a delay in the conveyance timing of the envelope 100E, a shift in the printing position, and a jam.

  9A shows an envelope 100E from any one of the paper feed trays 22 to 24 of the paper feed unit 2 to the paper feed route RS of the paper feed transport unit 31, or from the reverse transport unit 36 to the paper feed route RS. The sheet is fed with the flap 102 at the leading end side in the transport direction and with the flap 102 in the open state, and the registration roller 37 shows a state where slack is generated at the leading end side in the transport direction of the envelope 100E. In this case, the leading end of the flap 102 of the envelope 100E comes into contact with the registration roller 37 and the transport of the leading end portion is temporarily stopped. However, the transport roller 206 or 366 continues to transport the envelope 100E on the rear end side in the transport direction. Therefore, the envelope 100E is loosened between the registration roller 37 and the transport roller 206 or 366. Similar to the conveyance state shown in FIG. 8A, the flap 102 has a small number of sheets folded with respect to the main body 101, and the mechanical rigidity of the looseness of the envelope 100E is weak. The repulsive force F1 due to the slack reaction is small. Accordingly, the slip between the envelope 100E and the transport roller 206 or 366 is small, and the assist speed of the envelope 100E of the transport roller 206 or 366 is increased.

  FIG. 9C shows the relationship between the rotation speeds of various rollers and the conveyance time, as in FIG. 8C. As described above, in the conveyance of the envelope 100E with the flap 102 shown in FIG. 9A as the leading end in the conveyance direction, the assist speed of the conveyance roller 206 is increased due to the repulsive force F1, and thus the assist speed calculation unit 802 Calculates a correction value for slowing down the assist speed of the transport roller 206 or 366 and adjusting it to an appropriate assist speed. There is a time zone in which the assist speed of the transport roller 206 or 366 becomes a constant transport speed after increasing, but this is a time zone from the transport roller 206 or 366 until the envelope 100E is sent from the registration roller 37 to the print transport unit 32. is there.

  On the other hand, FIG. 9B shows an envelope 100E from any of the paper feed trays 22 to 24 of the paper feed unit 2 to the paper feed route RS of the paper feed transport unit 31 or from the reverse transport unit 36 to the paper feed route RS. The sheet is fed with the flap 102 at the rear end side in the transport direction and the flap 102 in the open state, and the registration roller 37 shows a state where slack is generated at the front end side in the transport direction of the envelope 100E. In this case, the leading end of the portion 1012 of the main body 101 of the envelope 100E that comes in contact with the registration roller 37 comes into contact with the leading end portion to stop the transporting of the leading end portion. Is being continued, the looseness of the envelope 100E occurs between the registration roller 37 and the transport roller 206 or 366. Since the main body 101 has a large number of sheets folded with respect to the flap 102 and the mechanical rigidity of the slack of the envelope 100E is strong, the repulsive force F2 due to the slack reaction to the transport roller 206 or 366 side is large. Therefore, the slip between the envelope 100E and the transport roller 206 or 366 is large, and the assist speed of the envelope 100E of the transport roller 206 or 366 is slow.

  9C, as described above, in the conveyance of the envelope 100E with the main body 101 shown in FIG. 9B as the leading end in the conveyance direction, the assist speed of the conveyance roller 206 is slow due to the repulsive force F2. Therefore, the assist speed calculation unit 802 calculates the correction value for increasing the assist speed of the transport roller 206 and adjusting the assist speed to an appropriate assist speed.

  In the assist speed calculation unit 802, the correction value includes the envelope information size of the envelope 100E, the direction of the envelope 100E in the transport direction, the opening / closing state of the flap of the envelope 100E, and the paper type (rigidity (stiffness) of the envelope 100E as necessary. ), Friction coefficient, etc.) are multiplied by a coefficient calculated based on an experimental value or an empirical value. Further, the assist speed calculation unit 802 may store the correction value calculated in advance as a table corresponding to the envelope information, and take out the correction value according to the corresponding envelope information.

  The correction value calculated by the assist speed calculation unit 802 is output to the assist speed adjustment unit 803. The assist speed adjusting unit 803 performs drive control of the drive circuit 220 and adjusts the assist speed of the transport roller 206 through the drive circuit 220 and the transport unit drive source 231 according to the correction value. The assist speed adjusting unit 803 performs drive control of the drive circuit 220 and adjusts the assist speed of the transport roller 366 through the drive circuit 220 and the reverse transport unit drive source 232 according to the correction value.

  The head driving unit 610 of the printing unit 6 is connected to the control IC 80 and adjusts a voltage applied to a piezoelectric element (not shown) of the print head 61 based on a control signal of the control IC 80 to 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 adjustment 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 to an appropriate value based on the detection result of the medium thickness detection 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 plastic template 63 is moved in the vertical direction using the drive source (the direction toward or away from the print head 61). The head gap is adjusted by moving to.

  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.

[Envelope printing method of image forming apparatus]
As shown in FIG. 10, the printing method (assist speed correction method) of the envelope 100E of the image forming apparatus 1 according to the embodiment is as follows.

  First, for example, a front image 1013 printed on the front surface of the main body 101 of the envelope 100E and a back image 1014 printed on the back surface of the main body 101 are generated using an external terminal (for example, a personal computer) (S1). This image information is stored in the image information storage unit 81 of the control unit 8 of the image forming apparatus 1, and more specifically, in the envelope print image information storage unit 8102 (see FIG. 4) (S2).

  Next, when printing the envelope 100E, it is determined whether or not the existing envelope information including the shape, thickness, etc. of the envelope 100E has been stored in the envelope shape information storage unit 8101 of the envelope information storage unit 810 (S3). If the envelope information of the existing value is not stored, the envelope information is stored (S31), and the process returns to step S3 again.

  When the envelope information of the existing value is stored in the envelope shape information storage unit 8101, it is determined whether or not the expansion of the image information stored in the envelope print image information storage unit 8102 has been completed (S4). In the image information development, a front image 1013 printed on the front surface of the main body 101 of the envelope 100E is developed as print information, and a back image 1014 printed on the back surface of the main body 101 and the front surface of the flap 102 is developed into print information. Means that This print information is stored in the envelope image information expansion unit 812. If the image information is not expanded, the process returns to the previous step and the image information is expanded.

  When the development of the image information has been completed, a transport operation (sheet passing operation) for detecting the shape (size) of the envelope 100E, the direction of the envelope 100E in the transport direction, the open / close state of the flap 102 of the envelope 100E, and the like. Is determined whether or not is necessary (S5). When it is determined that the sheet passing operation is necessary, the envelope 100E is supplied from, for example, the sheet feeding tray 21 of the sheet feeding unit 2 of the image forming apparatus 1 to the sheet feeding / conveying unit 31 of the conveying unit 3, and the sheet passing operation (feeding) is performed. Paper operation) is started (S6).

  It is detected whether or not the envelope 100E as the recording medium 100 conveyed in the paper feed conveyance unit 31 has passed through the medium detection unit 25, the medium thickness detection unit 26, and the envelope shape detection unit 27 (S7). The envelope shape detection unit 27 detects the shape of the envelope 100E, the medium thickness detection unit 26 detects the thickness of each region of the envelope 100E, and envelope information is detected (S8). In the detection of the envelope information, the detection output of the medium conveyance amount detection unit 28 is used together. The detection result of the envelope information is stored in the envelope shape information acquisition unit 82 (S9). In the envelope shape determining means 801 disposed in the control IC 80, the existing envelope information stored in the envelope shape information storage unit 8101 and the envelope information acquired and stored in the envelope shape information acquisition unit 82 are collated. When the two coincide, at least each information of the shape of the envelope 100E, the conveyance direction of the envelope 100E, and the open / close state of the flap 102 of the envelope 100E is determined (S10).

  When the envelope information of the envelope 100E is determined, first, the direction of the envelope 100E in the transport direction is determined, so it is determined whether or not the leading end side in the transport direction of the envelope 100E that starts printing is the flap 102 ( S11). Subsequently, when the leading end side in the transport direction of the envelope 100E is the flap 102, it is determined whether the flap 102 of the envelope 100E is in an open state or a closed state (S12). When it is determined that the flap 102 of the envelope 100E is in the open state, the repulsive force F1 when the slack is generated by the registration roller 37 is small (the waist is weak), the slip between the transport roller 206 and the envelope 100E is small, and the assist is performed. Since the speed is increased, the assist speed calculation unit 802 calculates a correction value for reducing the assist speed of the transport roller 206 shown in FIG. 8C (S13).

  In order to finish the sheet passing operation and start printing on the envelope 100E, the envelope 100E is fed from the transport tray 21 of the paper feed unit 2 to the paper feed path RS of the paper feed transport unit 31 using the paper feed roller 201. The envelope 100E is conveyed to the registration roller 37 using the conveyance roller 206. The leading end side of the envelope 100E in the conveying direction comes into contact with the registration roller 37 and stops temporarily, and a slack is generated in the envelope 100E. Thereafter, the registration roller 37 is driven at a predetermined delivery timing (S15). Based on the correction value calculated by the assist speed calculation unit 802, the assist speed adjustment unit 803 passes through each of the drive circuit 220 and the transport unit drive source 231. Thus, the transport roller 206 is driven at a low assist speed and an appropriate assist speed (S16). Since the conveyance roller 206 is adjusted to an appropriate assist speed, it is possible to prevent the occurrence of noise that occurs when the slack is stretched all at once when the envelope 100E of the registration roller 37 is sent out. Further, it is possible to prevent the occurrence of back tension applied to the envelope 100E generated at this time.

  When the assist operation ends (S17), the transport operation by the transport roller 206 ends (S18). Printing is started in the printing unit 6 on the envelope 100E conveyed to the printing conveyance unit 32 (S19). The envelope 100E that has been printed is discharged to the discharge tray of the discharge unit 4 or 5 (S20).

  On the other hand, when the front end in the transport direction of the envelope 100E that starts printing in step S11 is the main body 101, or in the closed state in step S12, the repulsive force F2 when slack is generated by the registration roller 37 is large (the waist is strong). ) Since the slip between the transport roller 206 and the envelope 100E is large and the assist speed is slow, the assist speed calculation unit 802 calculates a correction value for increasing the assist speed of the transport roller 206 shown in FIG. (S14). Thereafter, the processing after step S15 is performed. Also in this case, since the conveying roller 206 is adjusted to an appropriate assist speed, it is possible to prevent the occurrence of noise that occurs when the slack is stretched all at once when the envelope 100E of the registration roller 37 is sent out. Further, it is possible to prevent the occurrence of back tension applied to the envelope 100E generated at this time. That is, the assist speed can be adjusted appropriately regardless of the direction of the envelope 100E in the transport direction and the open / closed state of the flap 102 (without concern for the user).

  The same applies to the case where the envelope 100E is fed from the paper feed trays 22 to 24 of the paper feed unit 2 and is fed again from the reverse conveyance unit 36 by double-sided printing.

[Features of Example]
In the image forming apparatus 1 according to the above-described embodiment, the envelope information of the envelope 100E is detected using the envelope information detection unit, and the conveyance using the conveyance unit drive source 231 is performed based on the envelope information using the assist speed control unit. The assist speed of the roller 206 or the reverse conveyance unit drive source 232 can be adjusted. Accordingly, the assist speed of the transport roller 206 or 366 can be appropriately adjusted in printing on the envelope 100E, so that back tension is not generated and noise can be prevented. Furthermore, it is possible to prevent a conveyance failure such as a conveyance timing delay, a printing position shift, and a jam, so that the printing time can be increased.

  In the image forming apparatus 1 according to the embodiment, the size of the main body 101 of the envelope 100E, the size of the flap 102 of the envelope 100E, the transport direction of the envelope 100E, and the opening / closing state of the flap of the envelope 100E using the envelope information detection unit Since the envelope information having each of the above information can be detected, the assist speed can be appropriately adjusted according to the conveyance form of the envelope 100E.

  In the image forming apparatus 1 according to the embodiment, the size of the main body 101 of the envelope 100E and the size of the flap 102 are detected using the envelope shape detection unit 27 of the envelope information detection unit, and the medium thickness detection unit 26 is used. By detecting the thickness of the main body 101 and the thickness of the flap 102, the envelope information of the size and thickness of the main body 101 of the envelope 100E and the size and thickness of the flap 102 can be obtained, and the envelope 100E is conveyed. The envelope information of the direction and the open / close state of the flap 102 of the envelope 100E can be extracted.

  Further, in the image forming apparatus 1 according to the embodiment, the assist speed of the transport roller 206 or 366 using the assist speed calculation unit 802 of the assist speed control unit based on the envelope information detected using the envelope information detection unit. Based on the calculated assist speed, the driving speed of the transport roller 206 of the transport section drive source 231 or the transport roller 336 of the reverse transport section drive source 232 can be adjusted using the assist speed adjustment section 803. Therefore, the assist speed can be appropriately adjusted according to the conveyance form of the envelope 100E.

  Further, in the image forming apparatus 1 according to the embodiment, using the assist speed control unit, in the envelope information detection unit, the flap 102 of the envelope 100E is in the open state and the flap 102 is at the leading end side in the conveyance direction of the envelope 100E. Since the assist speed at the time of detection is controlled to be slow, and the assist speed when it is detected that the flap 102 of the envelope 100E is in the closed state and the flap 102 is at the rear end side in the conveyance direction of the envelope 100E can be controlled quickly. The assist speed can be appropriately adjusted according to the transport mode of 100E.

(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.

  INDUSTRIAL APPLICABILITY The present invention can be widely applied to image forming apparatuses that can appropriately adjust the assist speed of the conveyance roller in envelope printing, prevent noise, and increase the printing time.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 100 ... Recording medium, 100E ... Envelope, 101 ... Main body, 102 ... Flap, 1013 ... Front image, 1014 ... Back image, 103 ... Folding area, 2 ... Paper feed part, 21-24 ... 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, 220 ... drive circuit, 210 ... feeding conveyance unit drive source, 211 ... registration roller Drive source, 212... Discharge transport unit drive source, 230... Belt drive source, 231... Transport unit drive source, 232 .. reverse transport unit drive source, 3. , 33 ... Ascending conveyance unit, 34 ... Horizontal conveyance unit, 35 ... Discharge conveyance unit, 36 ... Reverse conveyance unit, 4, 5 ... Discharge unit, 6 ... Printing unit, 61 ... Print head, 610 ... Head gap drive unit 611 ... Head G Adjustment unit, 6101 ... ink ejection timing adjustment unit, 62 ... ink circulation unit, 63 ... plastic template, 7 ... suction device, 8 ... control unit, 80 ... control IC, 801 ... envelope shape determining means, 802 ... assist speed Calculation unit, 803 ... assist speed adjustment unit, 81 ... image information storage unit, 810 ... envelope information storage unit, 8101 ... envelope shape information storage unit, 8102 ... envelope print image information storage unit, 811 ... image information expansion unit, 812 ... Envelope image information expansion unit, 82... Envelope shape information acquisition unit, 83... Interface unit, 84.

Claims (5)

A registration roller that adjusts the delivery timing of the envelope conveyed to the conveyance path to the printing unit;
A registration roller driving source for driving the registration roller;
A transport roller disposed upstream of the registration rollers in the transport path and delivering the envelope to the registration rollers;
A transport unit drive source for driving the transport roller;
Envelope information detection means that is disposed in the transport path and detects envelope information including information on the transport direction of the envelope and flap opening / closing of the envelope;
Assist speed control means for adjusting the transport speed of the transport roller that transports the envelope to the registration roller based on the envelope information;
An image forming apparatus comprising:   The envelope information detecting means detects the envelope information further including information on a size of a main body of the envelope, a size of a flap of the envelope, or a paper type of the envelope. The image forming apparatus described.   The envelope information detection unit includes an envelope shape detection unit that detects the size of the main body and the flap of the envelope, and a medium thickness detection unit that detects the thickness of the main body and the thickness of the flap. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The assist speed control unit includes an assist speed calculation unit that calculates a transport speed of the transport roller based on the envelope information detected by the envelope information detection unit, and a transport speed calculated by the assist speed calculation unit. 4. The image forming apparatus according to claim 1, further comprising: an assist speed adjusting unit configured to adjust a driving speed of the transport roller of the transport unit driving source.   The assist speed control means, in the envelope information detection means, with respect to the transport speed when the flap of the envelope is detected to be in the open state and the flap is the leading end side in the transport direction of the envelope. The image according to any one of claims 1 to 4, wherein the conveyance speed when the flap is detected to be closed and the flap is detected to be on the rear end side in the conveyance direction of the envelope is controlled to be high. Forming equipment.