JP2008058407A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an image forming apparatus from being damaged by accurately detecting conveying failure in a fixing unit even when toner is distributed to the end part of transfer material. <P>SOLUTION: The image forming apparatus is provided with: a transferring means for transferring a toner image formed on a photoreceptor to the transfer material; a fixing means for conveying the transfer material by holding the material between a heating member heated by a heating body and a pressurizing member and fixing the toner image to the transfer material; a first transfer material detecting means installed in a position on an upstream side of a fixing point of the fixing means; and a second transfer material detecting means which is installed in a position on a downstream side of a fixing nip part and detects that the transfer material is passing through the fixing nip part of the fixing means. An engine control part 206 detects conveying failure of the transfer material according to the detected result by the first and the second transfer material detecting means, detects conveying failure of the transfer material and varies the timing for detecting the conveying failure of the transfer material according to toner distribution to the transfer material to be fixed using the fixing means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method. More specifically, an image having a fixing unit for fixing a toner image on a transfer material such as an electrophotographic apparatus, in which the detection timing of transfer material conveyance failure is changed according to the amount of toner at the leading end of the transfer material. The present invention relates to a forming apparatus and an image forming method.

  It is known to employ a fixing device in an image forming apparatus configured as a copying machine, a printer, a facsimile, or a multifunction machine having at least two of these functions. In such a fixing device, the toner carried on the transfer material passes through a fixing nip formed by a fixing member and a pressure member. At that time, since the toner melts in the fixing nip portion, the melted toner acts as an adhesive, and the transfer material exiting the fixing nip portion may wrap around the surface without being separated from the surface of the fixing member. There is.

  In particular, in an image forming apparatus that forms a full-color image, a plurality of toner images of different colors are formed on a transfer material by being superimposed, and the formed toner image is fixed by a fixing device. A large amount of toner will melt. For this reason, the adhesion of the toner is increased by this melting, and the transfer material is more easily wound around the fixing member.

  FIG. 10 is a diagram illustrating a transfer material in which a blank portion is provided at the leading end of the transfer material in a conventional image forming apparatus. In this conventional image forming apparatus, there is a method of reducing the occurrence of wrapping in the fixing portion that is difficult to restore by providing a margin so as not to form a toner image at the end portion of the transfer material, particularly the leading end portion in the transport direction. Adopted.

  In addition, an image processing system and an image recording method capable of forming an image over the entire area of the recording material according to the characteristics and type of the recording material are known (for example, see Patent Document 1). The device described in Patent Document 1 includes an image forming apparatus and an image transmitting apparatus. The image transmission apparatus includes a control device for the image transmission apparatus that enables image formation over the entire area of the recording material in the borderless printing mode of the image forming apparatus according to the characteristics and type of the recording material on which the image is recorded. . In addition, the control device performs control so that an image can be formed on the entire area of the recording material in the borderless printing mode of the image forming apparatus according to the characteristics and type of the recording material on which the image is recorded. It is effective and effective when an image is to be recorded on the entire area of a specific feature or type of recording material such as cardboard, OHP sheet, envelope, special paper, postcard, and business card.

JP 2004-5559 A

  However, in recent years, in electrophotography, there has been an increasing demand for borderless printed matter in which toner is distributed to the end of the transfer material. As described above, the borderless printing function in which the toner is distributed to the end of the transfer material is very easy to wind around the fixing member. Further, when borderless printing is performed, it is difficult to accurately detect a conveyance failure of the fixing unit and reliably prevent damage to the image forming apparatus.

  Therefore, conventionally, even when a printed material without a border is obtained, a function of automatically cutting a margin of a transfer material printed with a margin in order to prevent the image forming apparatus from being damaged due to the occurrence of winding in the fixing unit. It was mounted on an electrophotographic apparatus.

  An object of the present invention is to provide an image forming apparatus and an image forming apparatus capable of accurately detecting a conveyance failure in a fixing unit and preventing damage to the image forming apparatus even in a case where toner is distributed to the end of a transfer material. It is to provide a method.

  Also provided are an image forming apparatus and an image forming method which avoid secondary damage to an image forming apparatus by improving jam handling even when a conveyance failure occurs in a fixing unit. It is in.

  The present invention has been made to achieve such an object. An image forming apparatus according to the present invention includes a transfer unit that transfers a toner image formed on an image carrier to a transfer material, and a heating body. A fixing unit that sandwiches and conveys the transfer material by a heated heating member and a pressure member, and fixes a toner image on the transfer material, and a fixing that fixes the toner image on the transfer material by the fixing unit A first transfer material detecting means installed at a position upstream of the transfer material conveyance direction, and detecting that the transfer material has passed the fixing position of the fixing means, and the transfer material at the fixing position A second transfer material detection unit installed at a position downstream in the conveyance direction; a detection unit that detects a conveyance failure of the transfer material according to detection results of the first and second transfer material detection units; Formed on the transfer material to be fixed using the fixing means; According to the distribution of toner images, characterized by comprising a changing means for changing the timing of detecting the bad conveyance of the transfer material.

  Further, the image forming method of the present invention comprises a transfer step for transferring a toner image formed on an image carrier to a transfer material, a heating member heated by a heating body, and a pressure member. A fixing step for nipping and conveying and fixing a toner image on the transfer material, and a first detection step by a first transfer material detecting means installed upstream of the fixing position in the fixing step in the transfer material conveyance direction And a second detection step by a second transfer material detecting means installed at a position downstream of the fixing position in the transfer material conveyance direction, detecting that the transfer material has passed through the fixing position; In accordance with the detection result of the detection step by the first and second transfer material detection means, a transfer failure detection step for detecting transfer failure of the transfer material, and the transfer material to be fixed in the fixing step are formed on the transfer material. Tona Depending on the distribution of the image, and having a changing step of changing the timing of detecting the bad conveyance of the transfer material.

  According to the present invention, even in the case of borderless printing in which toner is distributed to the end of the transfer material, it is possible to accurately detect a conveyance failure in the fixing unit and prevent damage to the image forming apparatus. Is possible. Further, even when a conveyance failure occurs in the fixing unit, it is possible to avoid secondary damage to the image forming apparatus by improving the jam handling performance.

Embodiments of the present invention will be described below with reference to the drawings.
(Example 1)
FIG. 1 is a cross-sectional view showing a configuration of a printer engine of an image forming apparatus according to the present invention.
<Overall Description of Image Forming Apparatus>
First, the overall configuration of the image forming apparatus 100 according to the present invention, that is, the configuration of the printer engine will be described below.

  The color laser printer engine has four image carriers (photosensitive drums) arranged in parallel in the vertical direction, rotating at a constant speed for each color of yellow (Y), magenta (M), cyan (C), and black (Bk). ) 1 (1a-1d). Further, a developing device 4 (4a to 4d) disposed in the vicinity of the image carrier 1 is provided. The image carrier 1 and the developing device 4 constitute an image forming unit 32. In addition, a transfer belt for sequentially transferring the transfer material S fed from the paper supply unit 16 to the image formation unit 32 in order to sequentially transfer the toner images developed in the image formation unit 32 onto the transfer material S. 11 is provided.

  The image carrier 1 is rotationally driven counterclockwise in the figure by a driving means (not shown), and the surface of the image carrier 1 is uniformly distributed around the image carrier 1 according to the rotation direction. A charging device 2 (2a, 2b, 2c, 2d) for charging is disposed. Further, a laser unit is irradiated on the basis of the image information to form an electrostatic latent image on the image carrier 1 and a toner is attached to the electrostatic latent image, and a scanner unit 3 (3a, 3b, 3c, 3d). A developing device 4 (4a, 4b, 4c, 4d) for developing as a toner image is provided. Further, an electrostatic transfer device 5 that transfers the toner image on the image carrier 1 to the transfer material S, and a cleaning device 6 (6a, 6b, 6) that removes transfer residual toner remaining on the surface of the image carrier 1 after the transfer. 6c, 6d) and the like are provided.

  Here, the image carrier 1, the charging device 2, the developing device 4, and the cleaning device 6 form a process cartridge 7 (7a to 7d) integrally formed into a cartridge.

  Both ends of the image carrier 1 are rotatably supported by support members, and a driving force from a driving motor (not shown) is transmitted to one of the ends so as to rotate counterclockwise. Is done.

  As the charging device 2, a contact charging type can be used. The charging member is a conductive roller formed in the shape of a roller. The roller is brought into contact with the surface of the image carrier 1, and a charging bias voltage is applied to the roller so that the surface of the image carrier 1 is made. It is charged uniformly.

  The scanner unit 3 is arranged in a substantially horizontal direction of the image carrier 1, and image light corresponding to an image signal is rotated at high speed by a scanner motor (not shown) by a laser diode (not shown). 9 (9a, 9b, 9c, 9d). The image light reflected by the polygon mirror 9 selectively exposes the surface of the charged image carrier 1 through the imaging lens 10 (10a, 10b, 10c, 10d) to form an electrostatic latent image. . The developing device 4 includes four color developing devices 4a, 4b, 4c, and 4d that respectively store toners of colors Y, M, C, and Bk.

  An electrostatic transfer belt (intermediate transport belt) 11 that is opposed to all the image carriers 1a, 1b, 1c, and 1d and circulates so as to be in contact with the image carrier 1 is provided. The electrostatic transfer belt 11 is supported by rollers in four directions in the vertical direction, and circulates and moves so that the transfer material S is electrostatically attracted to the outer peripheral surface on the left side in the drawing so that the transfer material S contacts the image carrier 1. To do. As a result, the transfer material S is conveyed to the transfer position by the electrostatic transfer belt 11 and transfers the toner image on the image carrier 1.

  A transfer roller 12 (12a, 12b, 12c, 12d) is arranged in parallel at a position in contact with the inside of the electrostatic transfer belt 11 and facing the four image carriers 1a, 1b, 1c, 1d. A positive charge is applied from the transfer roller 12 to the transfer material S via the electrostatic transfer belt 11, and a negative toner on the image carrier 1 is applied to the sheet in contact with the image carrier 1 by the electric field due to the charge. The image is transferred.

  The electrostatic transfer belt 11 is stretched around four rollers of a driving roller 13, driven rollers 14a and 14b, and a tension roller 15, and rotates in the direction of the arrow in the figure. As a result, the above-described electrostatic transfer belt 11 circulates and the toner image is transferred while the transfer material S is conveyed from the driven roller 14a side to the drive roller 13 side.

  The paper feed unit 16 feeds and conveys the transfer material S to the image forming unit, and a plurality of transfer materials S are stored in the paper feed cassette 17. At the time of image formation, the paper feed roller (half-moon roller) 18 and the registration roller pair 19 are driven and rotated according to the image forming operation, and the transfer material S in the paper feed cassette 17 is separated and fed one by one. Then, the leading edge of the transfer material S abuts against the registration roller pair 19 and temporarily stops. After forming a loop, the electrostatic transfer belt 11 is synchronized with the rotation of the electrostatic transfer belt 11 and the image writing position. Paper is fed to the belt 11.

  The fixing unit 20 fixes a plurality of color toner images transferred to the transfer material S, and includes a heating roller 21a that rotates, and a pressure roller 21b that presses and applies heat and pressure to the transfer material S. , And a discharge roller pair 23.

  That is, the transfer material S to which the toner image on the image carrier 1 is transferred is conveyed by the fixing roller pair 21 a and 21 b when passing through the fixing unit 20. At the same time, heat and pressure are applied by the pair of fixing rollers 21a and 21b, whereby a plurality of color toner images are fixed on the surface of the transfer material S.

  As an image forming operation, the process cartridge 7 is sequentially driven in accordance with the print timing, and the image carrier 1 is rotationally driven in the counterclockwise direction in accordance with the drive. Then, the scanner units 3 corresponding to the respective process cartridges 7 are sequentially driven. By this driving, the charging roller of the charging device 2 applies a uniform charge to the peripheral surface of the image carrier 1, and the scanner unit 3 exposes the peripheral surface of the image carrier 1 according to the image signal. Thus, an electrostatic latent image is formed on the peripheral surface of the image carrier 1. Developing rollers 40 (40a to 40d) in the developing device 4 transfer (toner) toner to the low potential portion of the electrostatic latent image to form (develop) a toner image on the peripheral surface of the image carrier 1.

  At the timing when the leading edge of the toner image on the peripheral surface of the uppermost image carrier 1 is rotated and conveyed to a point facing the electrostatic transfer belt 11, the printing start position of the transfer material S coincides with that point. To do. As such, the registration roller pair 19 starts rotating and feeds the transfer material S to the electrostatic transfer belt 11.

  The transfer material S is pressed against the outer periphery of the electrostatic transfer belt 11 so as to be sandwiched between the electrostatic adsorption roller 22 and the electrostatic transfer belt 11. Then, by applying a voltage between the electrostatic transfer belt 11 and the electrostatic adsorption roller 22, charges are induced in the transfer material S that is a dielectric and the dielectric layer of the electrostatic transfer belt 11, and the transfer material S Is electrostatically attracted to the outer periphery of the electrostatic transfer belt 11. As a result, the transfer material S is stably adsorbed to the electrostatic transfer belt 11 and conveyed to the most downstream transfer unit. While being conveyed in this manner, the toner image on each image carrier 1 is sequentially transferred to the transfer material S by an electric field formed between each image carrier 1 and the transfer roller 12.

  The transfer material S on which the four color toner images are transferred is separated from the electrostatic transfer belt 11 by the curvature of the belt driving roller 13 and is carried into the fixing unit 20. After the toner image described above is thermally fixed by the fixing unit 20, the transfer material S is discharged from the discharge tray 24 to the outside of the main body with the image surface facing down by the discharge roller pair 23. That is, the transfer material S to which the toner image has been transferred is conveyed to the fixing unit 20, and the color image is fixed to the transfer material S, and is discharged to the discharge tray 24 on the upper surface of the apparatus by the discharge roller pair 23. The process cartridge 7 including the above-described four color developing devices 4a to 4d is configured to be individually detachable from the printer engine.

FIG. 2 is a diagram showing the configuration of the printer of the image forming apparatus according to the present invention.
The printer 201 includes a printer controller 202 and a printer engine 203, and the printer engine 203 includes a laser drive circuit 205 and an engine control unit 206. A printer controller 202 receives image information in a predetermined language from a host computer 204 which is an external device, and performs image development. At that time, as shown in FIG. 15, the image information sent from the host computer 204 considers the size of the transfer material to be printed and the amount of margin necessary for printing, as shown in FIG. Is converted to FIG. 15 is an image diagram showing the relationship between the transfer data and the print data with the leading edge margin created by the printer controller of the image forming apparatus according to the present invention.

  When the user designates borderless printing, as shown in FIG. 16, the printer controller 202 converts the image data to a size larger by a predetermined amount than the size of the transfer material. FIG. 16 is an image diagram showing the relationship between the transfer data and the print data having no leading margin created by the printer controller of the image forming apparatus according to the present invention.

  The inverted TOP signal / TOP shown in the figure is a vertical synchronization signal, and is a signal that falls at the leading edge of the print transfer material. The inverted LSYNC signals / LSYNC1 to 4 are signals having the same cycle as the horizontal synchronization signal, and are signals for requesting the printer controller 202 from the engine control unit 206 to transfer image data for one line in the High period. .

  During the printing operation, the printer controller 202 described above receives image information from the host computer 204, and when the image development is completed and image data can be transmitted, the printer controller 202 prints to the engine control unit 206 of the printer engine 203. Sends commands.

  The printer controller 202 transmits a command for instructing borderless printing to the engine control unit 206 of the printer engine 203 at a timing before and after the print command as necessary. The engine control unit 206 of the printer engine 203 outputs a TOP signal to the printer controller 202 after receiving a print command from the printer controller 202. After detecting the TOP signal, the printer controller 202 sends image data VDO1 to VDO4 (0..7) to the laser drive circuit 205 of the printer engine 203 for a specified line during the period of the LSYNC signal, and drives the laser to perform electronic processing. It is printed by the photographic process.

Next, each component of the image forming apparatus of the present invention will be described in more detail.
<Intermediate conveyor belt>
The intermediate conveying belt 11 is illustrated in synchronism with the outer peripheral speed of the image carrier 1 in order to multiplex-transfer the toner image on the image carrier 1 visualized by each developing device 4 onto the transfer material S during the color image forming operation. Rotate clockwise. The transfer material S conveyed from the paper supply unit 16 is electrostatically held on the intermediate conveyance belt 11 and sequentially conveyed to each transfer unit. The toner image formed on the image carrier 1 is disposed at a position opposed to the image carrier 1 with the intermediate conveyance belt 11 interposed therebetween, and the intermediate conveyance belt at a transfer portion which is a contact point with the transfer roller 12 to which a voltage is applied. 11 is transferred onto the transfer material S on the substrate 11.

  The intermediate conveyance belt 11 is supported by the main body on four axes (13, 14a, 14b, 15) with the driving roller 13 as a fulcrum. By transmitting the driving force of a driving motor (not shown) to one end on the rear side of the driving roller 13 in the drawing, the intermediate conveying belt 11 is rotated in the clockwise direction in the drawing according to the image forming operation.

<Fixing part>
FIG. 3 is a diagram showing the configuration of the fixing unit of the image forming apparatus according to the present invention. Reference numeral 94 denotes a heater, which is a heating element, and is controlled so that the heater 94 is heated to a desired temperature by being supplied with power from a power source (not shown). Reference numeral 21a denotes a fixing film (heating roller) which is a rotating body and has a multilayer structure. Reference numeral 95 denotes a heater holder which also serves as a support member for the heater 94 and as a guide member that promotes smooth rotation of the fixing film 21a. Reference numeral 21b denotes a pressure roller as a pressure member, which presses and heats the transfer material S between the fixing film 21a and fixes the toner T.

  Further, downstream of the fixing nip portion, a mechanical conveyance flag 96 whose state is switched according to the conveyance state of the transfer material S, and a fixing sensor 97 configured to be obliquely transmitted and transmitted according to the state of the flag end portion. Is arranged. In addition, a paper discharge roller pair 23 is disposed downstream of the conveyance path so that the paper can be discharged smoothly from the fixing unit.

<Image forming operation>
Next, an operation when image formation is performed by the image forming apparatus configured as described above will be described.
First, the sheet feeding roller 18 shown in FIG. 1 is rotated to separate one transfer material S in the sheet feeding cassette 17 and conveyed to the registration roller 19. On the other hand, the image carrier 1 and the intermediate conveyance belt 11 rotate in the direction indicated by the arrow at a predetermined outer peripheral speed V (hereinafter referred to as a process speed).

  The image carrier 1 whose surface is uniformly charged by the charging device 2 is subjected to laser exposure to form an image. The scanner unit 3 irradiates an image with a laser to form a latent image on the image carrier 1. Simultaneously with the formation of the latent image, the developing roller 40 (40a to 40d) is driven, and a voltage having the same polarity and the same polarity as the charging polarity of the image carrier 1 is applied so that the toner adheres to the latent image on the image carrier 1. Apply to develop. At the same time, the toner image on the image carrier 1 is transferred to the transfer material S on the intermediate conveyance belt 11 at the transfer position downstream of the developing device 4. At this time, transfer is performed by applying a voltage having a reverse characteristic to the toner image described above to the transfer portion.

  The above steps are performed separately for each of the four color toner images and at a timing such that the leading edges of the toner images on the transfer material S coincide. As described above, a full-color image is formed by multiple transfer of the four color toner images onto the transfer material S.

  The transfer material S to which the full-color image has been transferred is peeled off from the intermediate conveyance belt 11 in FIG. 1, conveyed to the fixing unit 20 and fixed with toner, and then discharged through the discharge roller pair 23 to the discharge tray 24 at the top of the main body. The image is discharged with the image surface facing downward, and the image forming operation ends.

Next, the image forming apparatus of the present invention will be described with reference to FIGS.
The printer controller 202 shown in FIG. 2 receives image information from the host computer 204. Then, after executing the image development processing, when executing a print command and borderless printing to the printer engine 203, a command for instructing borderless printing is transmitted before and after that.

  FIG. 4 is a diagram for explaining the timing at which a transfer material having a front end margin is conveyed to the fixing unit of the image forming apparatus according to the present invention. FIG. 5 is a front view of the fixing unit of the image forming apparatus according to the present invention. It is a figure for demonstrating the timing at which the transfer material without a margin was conveyed.

  As shown in FIG. 4, when the margin enters the fixing unit 20 with the margin at the leading edge of the transfer material S, and when the borderless printing is performed as shown in FIG. The separation point of the transfer material S is different by the conveyance distance ΔL. Therefore, when the printer engine 203 is instructed to perform borderless printing from the host computer 204, when the conveyance speed is PS, the conveyance failure is detected in the fixing unit 20 for the time necessary for ΔL / PS. The timing shall be changed.

  A mechanism for detecting a conveyance failure in this embodiment will be described with reference to FIGS. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b). FIGS. 6A and 6B are timing charts for explaining detection of conveyance failure of the fixing unit when a transfer material having a leading edge margin is conveyed. FIG. 6A shows the upstream sensor shown in FIG. The detection timing in the fixing sensor shown in FIG. FIGS. 7A and 7B are timing charts for explaining the conveyance failure detection of the fixing unit when a transfer material having no leading edge margin is conveyed. The upstream sensor shown in FIG. The detection timing in the fixing sensor shown in FIG.

  As shown in FIG. 6A, when the transfer material S is conveyed, a point 603 at which an upstream sensor (not shown) of the fixing unit 20 changes the paper presence / absence signal from paper absence to paper presence. A point 604 that changes from the presence of paper to the absence of paper occurs. In the fixing unit 20, the timing at which a predetermined timing T <b> 1 determined by the distance from the upstream sensor and the conveyance speed has elapsed is set as the center of the conveyance timing in the fixing sensor 97. Then, detection of the presence / absence of the conveying material is started from the center at the timing 601 before T2, and if the leading edge of the transfer material cannot be detected from the center to the timing at 602 after T3, the conveyance failure at the fixing unit. As a notification. Also, as shown in FIG. 6B, when the leading edge of the transfer material S ideally reaches the fixing sensor, the paper presence / absence signal in the fixing sensor changes to paper presence at the timing of 605, It changes to no paper at the timing of 606.

  Further, as shown in FIG. 7A, when the transfer material S is conveyed, the upstream sensor of the fixing unit 20 changes from a paper absence to a paper presence point 603 and a paper presence to a paper absence. Point 604 is generated. In the fixing unit 20, the time obtained by adding ΔL / PS to the timing at which the predetermined timing T1 determined by the distance from the upstream sensor and the conveying speed has elapsed is set as the center of the conveying timing in the fixing sensor. Then, detection of the presence / absence of the conveying material is started from the center at the timing 607 before T2, and when the leading edge of the transfer material cannot be detected from the center to the timing 608 after T3, the conveyance at the fixing unit 20 is performed. Notify as defective. Further, as shown in FIG. 7B, when the leading edge of the transfer material S ideally reaches the fixing sensor, the paper presence / absence signal in the fixing sensor changes to paper presence at the timing 609, It changes to no paper at the timing of 610.

  By controlling as described above, the risk of detecting the conveyance of the transfer material S in the fixing sensor at an unnecessary timing is reduced even in the case of performing borderless printing that is likely to cause winding in the fixing unit. . In addition, due to the influence of electrical noise, mechanical chattering, etc., the conveyance failure that should be detected cannot be detected, and as a result, the risk of causing failure of the fixing unit and the printer engine itself is reduced, and reliability is improved. High conveyance failure detection is possible.

  In this embodiment, when an instruction for borderless printing is given, an example in which the conveyance defect detection timing in the fixing unit is changed by the time required for ΔL / PS when the conveyance speed is PS. It is shown. This changing time is not limited to the above-described embodiment.

(Example 2)
Since the configuration of the second embodiment is the same as that of the first embodiment, the description thereof is omitted here.
Next, Example 2 will be described with reference to FIGS. 2 and 6 to 9.

  The printer controller 202 shown in FIG. 2 receives image information from the host computer 204. Then, after the process of executing the image development is completed, the print command and the ratio of the toner image up to the transfer material front end Xmm are transmitted to the printer engine 203 as shown in FIG. .

  FIG. 8 is a view showing a tip Xmm portion of the transfer material of the image forming apparatus according to the present invention, and FIG. FIG. 6 is a diagram illustrating a shift amount of a separation point of a transfer material at a position.

  As shown in FIG. 9, the separation point of the transfer material S from the fixing film 21a changes according to the ratio of the toner image up to the tip Xmm of the transfer material S. The shift amount ΔL of the separation point of the transfer material S from the fixing film 21a can be determined from the data shown in FIG. 9 and the ratio of the toner image up to the tip Xmm of the transfer material S instructed from the printer controller 202. It is. The printer engine 203, when instructed by the host computer 204 to the ratio of the toner image from the transfer material S to the tip Xmm, takes the time required for ΔL / PS when the conveyance speed is PS. It is assumed that the conveyance failure detection timing is changed.

  With reference to the flowcharts shown in FIGS. 17 and 18, the flow of control for obtaining the separation point shift amount ΔL in the present embodiment will be described. FIG. 17 is a flowchart (part 1) for explaining the control on the printer controller side of the image forming apparatus according to the second embodiment of the present invention.

  When a print request is received from the host computer 204 to the printer controller 202, image information from the host computer 204 is received (S1701). Also, the transfer material size to be printed is acquired (S1702), and it is determined whether or not borderless printing is designated by the user (S1703). If not designated, image data with margins is created (S1704). If marginless printing is designated, image data without margins is created (S1705), and the ratio of the toner image in the area up to the tip Xmm of the image data is calculated (S1706). Then, the ratio at which the toner image in the area up to Xmm of the image data is created is transmitted to the printer engine 203 (S1707), and a print command is transmitted to the printer engine 203 (S1708). Then, it waits for the reception of the / TOP signal from the printer engine 203 (S1709), and after receiving the / TOP signal, it transmits the corresponding image data and ends (S1710).

  FIG. 18 is a flowchart (part 2) for explaining the control on the printer engine side of the image forming apparatus according to the second embodiment of the present invention. The printer engine 203 first receives the ratio of toner image creation in the area up to Xmm of the image data (S1801). Next, the process waits for a print command to be received (S1802), and then starts transporting the transfer material S (S1803), and transmits a / TOP signal at a predetermined timing (S1804). Then, the amount of separation point deviation ΔL is calculated from, for example, the data shown in FIG. 9 from the ratio of toner image creation in the area up to the tip Xmm of the image data transmitted from the printer controller 202 (S1805). ). Then, at the timing when the sheet is conveyed to the fixing unit, conveyance failure detection is performed based on the separation point deviation amount ΔL (S1806).

  Since the control after obtaining the separation point deviation amount ΔL is the same as that in the first embodiment, the description thereof is omitted here. Note that the control does not necessarily have to be the above-described procedure, and the above-described procedure is merely an example.

  By controlling as described above, even when printing with a toner image formed on the front end of the transfer material S, which is likely to cause wrapping in the fixing unit, the conveyance of the transfer material is detected by the fixing sensor at an unnecessary timing. Reduce the risk of going. In addition, due to the effects of electrical noise, mechanical chattering, etc., it is no longer possible to detect a conveyance failure that should be detected, and as a result, the risk of causing a failure of the fixing unit and the printer engine itself is reduced, and reliability is reduced. High conveyance failure can be detected. In the present embodiment, the method for determining the separation point deviation amount ΔL has been described with reference to FIG. 9, but the method for determining the separation point deviation amount ΔL is not limited to the above-described embodiment.

(Example 3)
Since the configuration of the third embodiment is the same as that of the first embodiment described above except for FIG. 2, the description thereof is omitted here.
Next, a third embodiment of the present invention will be described with reference to FIGS. 11 and 6 to 9.
FIG. 11 is a diagram illustrating a configuration of a printer according to the third exemplary embodiment of the image forming apparatus according to the present invention.

  The printer 1101 includes a printer controller 1102 and a printer engine 1108. The printer engine 1108 includes a laser drive unit 1103 including a laser PCB 1105 and a synchronization detection circuit 1106, and an engine control unit 1107. The printer controller 1102 receives image information from the host computer 1104, and transmits a print command to the printer engine 1108 after the process of executing image expansion is completed.

  The printer engine 1108 includes an engine control unit 1107, a laser PCB 1105, and a synchronization detection circuit 1106. Laser control signals (VDO1 to 4) from the printer controller 1102 pass through the engine control unit 1107, and horizontal sync signals (/ LSYNC1 to 4) from the sync detection circuit 1106 also pass through the engine control unit 1107. ing. The printer engine 1108 outputs the / TOP signal of the vertical synchronization signal at the timing when the transfer material is conveyed to a predetermined position after receiving the print command. After receiving / TOP, the printer controller 1102 counts predetermined horizontal synchronization signals (/ LSYNC1 to 4). Then, the laser control signals (VDO1 to VDO4) are output to the laser PCB 1105 in synchronization with the horizontal synchronization signals (/ LSYNC1 to 4) output from the printer engine 1108 from the timing when the sub-scan writing timing of each color is reached.

  In the third embodiment, the engine control unit 1107 performs a laser control signal (from the sub-scan writing timing of each color to the timing at which the horizontal synchronization signal (/ LSYNC1 to 4) corresponds to the position of the leading end Xmm of the transfer material S ( VDO1 to 4) are calculated and digitized. Then, the ratio of the toner image up to the tip Xmm of the transfer material S is calculated.

  As shown in FIG. 9, the separation point of the transfer material S from the fixing film 21a changes according to the ratio of the toner image up to the tip Xmm of the transfer material S. The deviation amount ΔL of the separation point of the transfer material S from the fixing film 21a can calculate the ratio of the toner image up to the tip Xmm of the transfer material S from the data shown in FIG. That is, it is possible to determine from the integrated value of the laser control signals (VDO1 to VDO4) up to the leading end Xmm of the transfer material S output from the printer controller 1102. The printer engine 1108 counts laser control signals (VDO1 to VDO4) output from the host computer 1104, and the engine control unit 1107 calculates the ratio of the toner image at the tip of the transfer material S. The amount of deviation ΔL of the transfer material separation point is calculated using the calculation result and FIG. 9, and the conveyance failure detection timing in the fixing unit is changed by the time required for ΔL / PS when the conveyance speed is PS. It shall be.

  A control flow for obtaining the separation point shift amount ΔL in the third embodiment will be described using the flowcharts shown in FIGS. 19 and 20. FIG. 19 is a flowchart (part 1) illustrating the control on the printer controller side of the image forming apparatus according to the third exemplary embodiment of the present invention.

  When a print request is received from the host computer 1104 to the printer controller 1102, image information from the host computer 1104 is received in step (S) 1901 in FIG. Further, the size of the transfer material S to be printed is acquired (S1902), and it is determined whether or not borderless printing is designated by the user (S1903). If not designated, image data with a margin is created (S1904). ). If borderless printing is designated, image data without margins is created (S1905), and a print command is transmitted to the printer engine 1101 (S1906). Then, it waits for reception of the / TOP signal from the printer engine 1101 (S1907), and after receiving the / TOP signal, transmits the corresponding image data and ends (S1908).

  FIG. 20 is a flowchart (part 2) for explaining the control on the printer engine side of the image forming apparatus according to the third embodiment of the present invention. The printer engine 1101 waits for a print command to be received (S2001), then starts transporting the transfer material S (S2002), and transmits a / TOP signal at a predetermined timing (S2003). Then, the laser control signal corresponding to the area up to the tip Xmm of the transfer material S transmitted from the printer controller 1102 is counted (S2004), and the ratio of the toner image up to the tip Xmm of the transfer material S is calculated (S2005). For example, the deviation amount ΔL of the separation point is calculated using the data of FIG. 9 (S2006), and conveyance failure detection based on the deviation amount ΔL of the separation point is performed at the timing when the separation point is conveyed (S2007).

  Since the control after obtaining the separation point deviation amount ΔL is the same as that in the first embodiment, the description thereof is omitted here. Note that the control does not necessarily have to be the above-described procedure, and the above-described procedure is merely an example.

  By controlling as described above, even when printing with a toner image formed on the front end of the transfer material S, which is likely to cause wrapping in the fixing unit, the conveyance of the transfer material is detected by the fixing sensor at an unnecessary timing. Reduce the risk of going. In addition, due to the influence of electrical noise, mechanical chattering, etc., the conveyance failure that should be detected cannot be detected. As a result, the risk of causing failure of the fixing unit and the printer engine itself is reduced and reliability is reduced. Therefore, it is possible to detect a high conveyance failure.

  In the third embodiment, an example of a circuit for calculating the ratio of the toner image at the tip of the transfer material S is shown. However, this circuit is an example, and the present invention is not limited to the above-described embodiment. Although the method for determining the separation point deviation amount ΔL has been described with reference to FIG. 9, the method for determining the separation point deviation amount ΔL is not limited to the above-described embodiment.

Example 4
Since the configuration of the fourth embodiment is the same as that of the first embodiment, the description thereof is omitted here.
Next, Example 4 will be described with reference to FIGS.
The printer controller 1102 shown in FIG. 11 receives image information from the host computer 1104, and transmits a print command to the printer engine 1108 after the process of executing image expansion is completed.

  The printer engine 1108 includes an engine control unit 1107, a laser PCB 1105, and a synchronization detection circuit 1106. The laser control signals (VDO1 to 4) from the printer controller 1102 pass through the engine control unit 1107, and the horizontal synchronization signals (/ LSYNC1 to 4) from the synchronization detection circuit 1106 also pass through the engine control unit 1107. It is configured. The printer engine 1108 outputs the / TOP signal of the vertical synchronization signal at the timing when the transfer material S is conveyed to a predetermined position after receiving the print command. After receiving / TOP, the printer controller 1102 counts predetermined horizontal synchronization signals (/ LSYNC1 to 4). The laser control signals (VDO1 to VDO4) are output in synchronization with the horizontal synchronization signals (/ LSYNC1 to 4) output from the printer engine 1108 from the timing when the sub-scanning writing timing of each color is reached.

  In the fourth embodiment, the engine control unit 1107 performs a laser control signal (from the sub-scan writing timing of each color to the timing at which the horizontal synchronization signal (/ LSYNC1 to 4) corresponds to the position of the leading end Xmm of the transfer material S ( VDO1 to 4) are calculated and digitized. Then, the ratio of the toner image up to the tip Xmm of the transfer material S is calculated.

  FIG. 12 is a diagram showing the toner ratio and the jam rate at the fixing portion at the tip Xmm of the transfer material of the image forming apparatus according to the present invention. It has been found that the rate of occurrence of wrapping jam in the fixing portion changes according to the ratio of the toner image up to the tip Xmm of the transfer material S. In addition, when a winding jam occurs, it is easier to eliminate the winding jam by detecting the conveyance failure earlier and stopping the printer engine 1108. Further, it has been found that the possibility that the printer engine 1108 is accidentally damaged when the user performs a recovery process for a difficult fixing portion winding state is reduced.

  Therefore, the fourth embodiment is designed to avoid damage that may be caused to the printer engine 1108 as a result of the improvement of the jam handling property of the winding jam in the fixing unit and the winding jam in the fixing unit. Therefore, as shown in FIG. 13, the conveyance failure detection timing in the fixing unit is changed by the time Δt according to the ratio of the toner image up to the tip Xmm of the transfer material S. FIG. 13 is a diagram showing the relationship between the toner ratio at the tip Xmm of the transfer material of the image forming apparatus according to the present invention and the conveyance failure detection timing shift amount Δt in the fixing unit.

  14A and 14B are timing charts showing detection of conveyance failure of the fixing unit according to the leading edge margin when the transfer material of the image forming apparatus according to the fourth exemplary embodiment of the present invention is conveyed. The detection timing in the upstream sensor shown to (a) and the fixing sensor shown in FIG.14 (b) is shown. That is, the conveyance failure detection timing according to the ratio of the toner image up to the tip Xmm of the transfer material S is shown.

  As shown in FIG. 14A, when the transfer material S is conveyed, the upstream sensor of the fixing unit 20 changes the point 1403 where the paper presence / absence signal changes from paper absence to paper presence, and from paper presence to paper. A point 1404 that changes without being generated is generated. In the fixing unit 20, the timing at which a predetermined timing T1 determined by the distance from the upstream sensor and the conveyance speed has elapsed is set as the center of the conveyance timing in the fixing sensor, and the presence / absence of the conveyance material is detected from the timing 1401 before T2 from the center. Start. Then, in consideration of Δt determined in FIG. 13 from the center, if the leading edge of the transfer material cannot be detected until the timing of 1402 after (T3−Δt), poor conveyance in the fixing unit 20 As a notification. Also, as shown in FIG. 14B, when the leading edge of the transfer material ideally reaches the fixing sensor, the paper presence / absence signal at the fixing sensor changes to paper presence at the timing of 1405 and 1406 Changes to no paper at the timing.

  By controlling as described above, it is possible to detect the winding at the fixing portion at an early stage, and even when performing printing in which the toner image is formed on the leading edge of the transfer material S, the winding jam at the fixing portion can be detected. It is possible to improve the jam handling performance. Further, damage that may be caused to the printer engine 1108 as a result of the winding jam in the fixing unit can be avoided as much as possible.

  In the fourth embodiment, although an example of a circuit for calculating the ratio of the toner image at the tip of the transfer material S is shown, this circuit is an example and is not limited to the above-described embodiment. Although the method for determining the timing shift amount Δt has been described with reference to FIG. 13, the method for determining the timing shift amount Δt is not limited to the above-described embodiment. Further, in the fourth embodiment, a method has been described in which the laser control signals (VDO1 to VDO4) from the printer controller 1102 are calculated and digitized to determine the ratio of the toner image up to the tip Xmm of the transfer material S. However, as described in the first embodiment, when a command for instructing borderless printing is received, the method can be easily applied to a method in which the ratio of the toner image at the tip of the transfer material S is regarded as a predetermined value. . Further, as described in the second embodiment, the printer engine 201 can be easily applied to a method of receiving the ratio of the toner image from the host computer 204 to the tip Xmm of the transfer material S.

1 is a cross-sectional view illustrating a configuration of a printer engine of an image forming apparatus according to the present invention. 1 is a diagram illustrating a configuration of a printer of an image forming apparatus according to the present invention. FIG. 3 is a diagram illustrating a configuration of a fixing unit of the image forming apparatus according to the present invention. FIG. 6 is a diagram for explaining a timing at which a transfer material having a leading edge margin is conveyed to the fixing unit of the image forming apparatus according to the present invention. FIG. 5 is a diagram for explaining timing when a transfer material having no leading edge margin is conveyed to the fixing unit of the image forming apparatus according to the present invention. FIG. 9 is a timing diagram for explaining detection of conveyance failure of the fixing unit when a transfer material having a leading edge margin is conveyed, and shows detection timings in the upstream sensor shown in (a) and the fixing sensor shown in (b). FIG. 6 is a timing diagram for explaining conveyance failure detection of the fixing unit when a transfer material having no leading edge margin is conveyed, and shows detection timings in the upstream sensor shown in (a) and the fixing sensor shown in (b). It is a figure which shows the part of the front-end | tip Xmm of the transfer material of the image forming apparatus which concerns on this invention. FIG. 4 is a diagram illustrating a toner ratio at a tip Xmm portion of a transfer material of an image forming apparatus according to the present invention and a transfer material separation point at a fixing unit. It is a figure which shows the transfer material which provided the margin part in the front-end | tip of the transfer material in the conventional image forming apparatus. FIG. 10 is a diagram illustrating a configuration of a printer according to a third exemplary embodiment of the image forming apparatus according to the present invention. FIG. 6 is a diagram illustrating a toner ratio at a tip Xmm portion of a transfer material of the image forming apparatus according to the present invention and a jam rate at a fixing unit. FIG. 6 is a diagram illustrating a relationship between a toner ratio at a tip Xmm portion of a transfer material of an image forming apparatus according to the present invention and a conveyance failure detection timing shift amount Δt at a fixing unit. FIG. 7 is a timing diagram illustrating detection of conveyance failure of the fixing unit according to the leading edge margin when the transfer material according to the fourth exemplary embodiment of the image forming apparatus according to the present invention is conveyed, and illustrates an upstream sensor illustrated in FIG. The detection timing in the fixing sensor is shown. FIG. 4 is an image diagram illustrating a relationship between print data having a leading edge margin created by a printer controller of the image forming apparatus according to the present invention and a transfer material. FIG. 4 is an image diagram illustrating a relationship between print data having no leading edge margin created by a printer controller of the image forming apparatus according to the present invention and a transfer material. FIG. 10 is a flowchart illustrating the control on the printer controller side of the image forming apparatus according to the second exemplary embodiment of the present invention. FIG. 10 is a flowchart for explaining control on the printer engine side of the image forming apparatus according to the second exemplary embodiment of the present invention. FIG. 10 is a flowchart illustrating the control on the printer controller side of the image forming apparatus according to the third exemplary embodiment of the present invention. FIG. 10 is a flowchart for explaining control on the printer engine side of the image forming apparatus according to the third exemplary embodiment of the present invention.

Explanation of symbols

1 (1a to 1d) Image carrier (photosensitive drum)
2 (2a, 2b, 2c, 2d) Charging device 3 (3a, 3b, 3c, 3d) Scanner unit 4 (4a-4d) Developing device 5 Electrostatic transfer device 6 (6a, 6b, 6c, 6d) Cleaning device 7 (7a-7d) Process cartridge 9 (9a, 9b, 9c, 9d) Polygon mirror 10 (10a, 10b, 10c, 10d) Imaging lens 11 Electrostatic transfer belt (intermediate transport belt)
12 (12a, 12b, 12c, 12d) Transfer roller 13 Drive rollers 14a, 14b Driven roller 15 Tension roller 16 Paper feed unit 17 Paper feed cassette 18 Paper feed roller (half moon roller)
19 Registration roller pair 20 Fixing portion 21a Heating roller (fixing film)
21b Pressure roller 22 Electrostatic adsorption roller 22
23 discharge roller pair 24 discharge tray 32 image forming unit 40 (40a to 40d) developing roller 94 heater 95 heater holder 96 conveyance flag 97 fixing sensor 201 printer 202 printer controller 203 printer engine 204 host computer 205 laser drive circuit 206 engine control unit 1101 Printer 1102 Printer Controller 1103 Laser Drive Unit 1104 Host Computer 1105 Laser PCB
1106 Synchronization detection circuit 1107 Engine control unit 1108 Printer engine

Claims (12)

Transfer means for transferring the toner image formed on the image carrier to a transfer material;
A fixing unit that sandwiches and conveys the transfer material between a heating member heated by a heating member and a pressure member, and fixes a toner image on the transfer material;
First transfer material detection means installed at a position upstream of the transfer material conveyance direction from the fixing position where the toner image on the transfer material is fixed by the fixing means;
Detecting that the transfer material has passed the fixing position of the fixing means, and a second transfer material detecting means installed at a position downstream of the fixing position in the transfer material conveyance direction;
Detection means for detecting a conveyance failure of the transfer material according to detection results of the first and second transfer material detection means;
An image forming apparatus comprising: a changing unit configured to change a timing for detecting a conveyance failure of the transfer material according to a distribution of a toner image formed on the transfer material to be fixed using the fixing unit. apparatus.   A borderless printing mode that enables printing without providing margins on the transfer material, and when the borderless printing mode is designated, there is no margin at the leading edge of the transfer material. The toner is distributed on the transfer material, and the changing unit changes the timing for detecting the transfer material conveyance failure performed using the second transfer material detecting unit. Item 2. The image forming apparatus according to Item 1.   An image processing unit that converts an image designated by the user into print data, and an arithmetic processing unit that calculates the amount of data to be printed on the leading end of the transfer material corresponding to the image processed in the image processing unit And the changing means detects the transfer material conveyance failure performed using the second transfer material detecting means in accordance with the amount of print data printed on the leading end of the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus is changed.   An image processing unit that converts an image designated by a user into print data, an image signal output unit that outputs the print data converted by the image processing unit as an image signal, and the output from the image signal output unit Image data computing means for computing image signals, and image writing means for forming an electrostatic latent image on a latent image carrier in accordance with the image signals output from the image signal output means, According to the amount of data printed on the front end portion of the transfer material, which is calculated by the image data calculation unit, the changing unit performs the transfer material conveyance failure performed using the second transfer material detection unit. The image forming apparatus according to claim 1, wherein the detection timing is changed.   Using the second transfer material detection means, the time corresponding to the amount of deviation of the separation position of the transfer material in the fixing means according to the ratio of the amount of toner transferred to the front end portion of the transfer material is used. 5. The image forming apparatus according to claim 1, wherein a timing for detecting a conveyance failure of the transfer material is changed.   6. The image according to claim 1, wherein the timing for detecting a winding jam in the fixing unit is changed in accordance with a ratio of the amount of toner transferred to the leading end portion of the transfer material. Forming equipment. A transfer step for transferring the toner image formed on the image carrier to a transfer material;
A fixing step of nipping and conveying the transfer material between a heating member heated by a heating body and a pressure member, and fixing a toner image on the transfer material;
A first detection step by a first transfer material detection means installed at a position upstream from the fixing position in the fixing step in the transfer material conveyance direction;
A second detection step by a second transfer material detection means that detects that the transfer material has passed through the fixing position and is located downstream of the fixing position in the transfer material conveyance direction;
A conveyance failure detection step of detecting a conveyance failure of the transfer material according to a detection result of the detection step by the first and second transfer material detection means;
An image forming method comprising: a changing step of changing a timing for detecting a conveyance failure of the transfer material in accordance with a distribution of a toner image formed on the transfer material to be fixed in the fixing step.   When the borderless printing mode for printing without a border on the transfer material is designated, the change is made assuming that the toner is distributed on the transfer material with no margin at the front end of the transfer material. The image forming method according to claim 7, wherein the step changes a timing for detecting a transfer material conveyance failure performed using the second transfer material detection unit. An arithmetic processing step for arithmetically processing an amount of data to be printed on the leading end portion of the transfer material, and the changing step is configured to perform the second processing according to the amount of print data printed on the leading end portion of the transfer material. The image forming method according to claim 7, wherein a timing for detecting a transfer material conveyance failure performed using the transfer material detection unit is changed.   An image processing step for converting an image designated by the user into print data, an image signal output step for outputting the print data converted in the image processing step as an image signal, and the output from the image signal output step An image data calculation step for calculating an image signal, and an image writing step for forming an electrostatic latent image on a latent image carrier in accordance with the image signal output from the image signal output step, In the changing step, the transfer material conveyance failure performed by using the second transfer material detecting unit according to the amount of data printed on the front end portion of the transfer material that has been calculated in the image data calculating step. The image forming method according to claim 7, wherein the detection timing is changed.   Using the second transfer material detection means, the time corresponding to the amount of deviation of the separation position in the fixing step of the transfer material according to the ratio of the amount of toner transferred to the front end portion of the transfer material. The image forming method according to claim 7, wherein a timing for detecting a transfer failure of the transfer material is changed. 12. The image according to claim 7, wherein the timing for detecting a winding jam in the fixing unit is changed in accordance with a ratio of the amount of toner transferred to the leading end portion of the transfer material. Forming method.

Images