JP2007178759A - Image printing device, image printing method and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain the deterioration of a fixing means and also to surely peel a printing medium from the fixing means. <P>SOLUTION: When the number of dots D in the leading edge area of paper P is larger than the allowable number of dots Dth in fixing (S110), a separation pawl is brought into contact with a heat roller when contact start timing T comes (S114). Thus, the leading edge of the paper P is easily peeled from the heat roller by the separation pawl. Meanwhile, after the leading edge of the paper P is peeled from the heat roller (S116), the separation pawl is separated from the heat roller (S118). Thus, the separation pawl is prevented from wearing or damaging the heat roller. By bringing the separation pawl into contact with the heat roller only when judging it as necessary based on printing data, the paper P is surely peeled from the heat roller while restraining the deterioration of the heat roller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image printing apparatus, an image printing method, and a program therefor.

Conventionally, as an image printing apparatus adopting an electrophotographic method, when fixing a toner image transferred to a sheet, a heat roller as a fixing unit and a pressure roller press the sheet while sandwiching the sheet to send out the sheet. There is known a technique in which toner is melted and fixed on a sheet (for example, Patent Document 1). In this image printing apparatus, the separation claw is arranged in a direction facing the rotation direction of the heat roller and close to the heat roller. Therefore, when the paper is fed from the heat roller, the separation claw enters between the paper and the heat roller, so even if the paper remains in close contact with the heat roller due to the adhesiveness of the molten toner, the paper is peeled off from the heat roller. Can do.
JP-A-2005-274888

  However, in Patent Document 1 described above, since the separation claw is not in contact with the heat roller, for example, when the toner adheres to the edge of the paper, such as borderless printing, the leading edge of the paper easily adheres to the heat roller. The separation claw is difficult to enter between the paper and the heat roller. For this reason, there is a possibility that the paper cannot be reliably peeled off from the heat roller with the non-contact type separation claw. Although it is conceivable that the heat roller and the separation claw are always brought into contact with each other, in this case, the heat roller is likely to deteriorate due to wear due to contact with the separation claw.

  The present invention has been made to solve the above-described problems, and an image printing apparatus, an image printing method, and a program thereof that can suppress deterioration of the fixing unit and can reliably peel the print medium from the fixing unit. The purpose is to provide.

  The present invention adopts the following means in order to achieve the above-mentioned object.

That is, the image printing apparatus of the present invention is
An image printing apparatus for printing an image on a print medium,
Fixing means for fixing the toner image to the surface of the print medium by sending out the print medium while being pressed against the print medium having the toner image transferred on the surface;
A peeling member capable of taking a first posture in which the front end of the print medium sent out by the fixing unit comes into contact with a position where the leading end can be peeled off from the fixing unit and a second posture separated from the fixing unit;
Positioning means for positioning the peeling member in the first posture or the second posture;
It is equipped with.

  In this image printing apparatus, when the peeling member is positioned in the first posture by operating the positioning means when the printing medium is sent out while being pressed against the fixing means, the leading edge of the printing medium is easily separated from the fixing means by the peeling member. Peel off. On the other hand, when the positioning member is operated to position the peeling member in the second posture after the leading edge of the printing medium is peeled off from the fixing means, the peeling member does not wear or damage the fixing means. Thus, by bringing the peeling member into contact with the fixing means only when necessary, the deterioration of the fixing means can be suppressed and the product life can be extended as compared with the case where the peeling member is always kept in contact with the fixing means. Also, if the peeling member is brought into contact with the fixing means, the peeling member can easily enter between the fixing means and the printing medium as compared with the case where the peeling member and the fixing means are not in contact with each other. Can be reliably peeled off.

  The image printing apparatus of the present invention further controls the positioning means so that the peeling member takes the first posture when the print medium is sent out from the fixing means by the fixing means, and the leading edge of the print medium After the peeling from the fixing means, a control means for performing positioning control for controlling the positioning means so that the peeling member takes the second posture may be provided. In this way, the peeling member can be brought into contact with the fixing unit only when necessary without requiring a complicated operation by the user.

  The image printing apparatus according to the present invention further includes a position detection unit that detects a position of the print medium, and the control unit performs the positioning control when the print medium is sent out from the fixing unit. Based on the position of the print medium detected by the position detection means, the timing for changing the peeling member from the second posture to the first posture is determined, and the peeling member is moved to the first posture at the determined timing. The positioning means may be controlled to take a posture. In this way, since the timing for bringing the peeling member into contact with the fixing unit is set based on the position of the printing medium, the peeling member is moved when the printing medium is sent to a position where the printing medium and the fixing unit need to be peeled off. It can be brought into contact with the fixing means.

  The image printing apparatus of the present invention further includes a peeling detection unit that detects whether or not a leading edge of the printing medium is peeled off from the fixing unit, and the control unit performs the positioning control when performing the positioning control. After the detection means detects that the leading edge of the print medium is peeled off from the fixing means, the positioning means may be controlled so that the peeling member takes the second posture. In this way, it is possible to accurately grasp that the front end of the print medium has been peeled off from the fixing unit, and the peeling member is not brought into contact with the fixing unit more than necessary.

  In the image printing apparatus according to the aspect of the invention, when the control unit performs the positioning control, the leading end of the print medium is moved from the fixing unit based on a time elapsed since the peeling member has taken the first posture. It may be determined whether or not the peeling member has peeled off, and after determining that the leading edge of the printing medium has peeled off from the fixing unit, the positioning unit may be controlled so that the peeling member takes the second posture. In this way, it is possible to grasp that the leading edge of the printing medium has been peeled off from the fixing means without providing a new detecting means for detecting that the leading edge of the printing medium has peeled off from the fixing means.

  The image printing apparatus of the present invention further includes an input unit for inputting image data, and the control unit determines whether or not to execute the positioning control based on the image data input to the input unit. It is good. The ease with which the print medium adheres to the fixing unit varies depending on the state of the image (for example, an image pattern) based on the image data. Therefore, it is preferable that the peeling member is brought into contact with the fixing unit only when it is determined that the print medium is difficult to peel from the fixing unit based on the image data.

  In the image printing apparatus of the present invention having the input unit as described above, the control unit grasps a margin amount in a predetermined area on the leading end side of the print medium from the image data, and the grasped margin amount is a predetermined margin amount. The positioning control may be executed when the number is less. In this way, the print medium can be reliably peeled off from the fixing unit even when the margin of the front end region of the print medium is small, and deterioration of the fixing unit can be effectively suppressed. Here, for example, the predetermined margin amount may be set in advance by experiments or the like as a lower limit value of the margin amount necessary for peeling the front end of the print medium from the fixing unit without using a peeling member. The predetermined area may be set as appropriate. At this time, the control means may execute the positioning control at the time of marginless printing in which the margin amount is very small or substantially zero. In borderless printing, the toner adheres to the entire surface of the print medium. Therefore, compared to printing with a margin on the edge of the print medium, the leading edge of the print medium is more likely to be in close contact with the fixing means, and the significance of applying the present invention is significant. high.

  In the image printing apparatus of the present invention including an input unit, the control unit detects the degree of toner adhesion in a predetermined region on the front end side of the print medium from the image data, and the detected degree of toner adhesion is detected. The positioning control may be executed when it is larger than a predetermined degree. In this way, the print medium can be reliably peeled off from the fixing unit even when the degree of toner adhesion at the leading end region of the print medium is large, and deterioration of the fixing unit can be effectively suppressed. it can. Here, the predetermined degree may be set, for example, by an experiment in advance as a lower limit value of the degree of adhesion of the toner that can peel the front end of the print medium from the fixing unit without using a peeling member. The predetermined area may be set as appropriate.

  In the image printing apparatus of the present invention, the control means may determine whether or not to execute the positioning control based on a type of the print medium. The ease with which the print medium adheres to the fixing means varies depending on the type of print medium (for example, the properties and materials of the print medium surface such as flatness and wetness, the thickness and size of the print medium, etc.). Therefore, it is preferable that the peeling member is brought into contact with the fixing unit only when it is determined that the printing medium is difficult to peel from the fixing unit based on the type of the printing medium. At this time, the control means may execute the positioning control when the print medium is thinner than a predetermined thickness. In this way, even when the thickness of the print medium is thin, the print medium can be reliably peeled off from the fixing unit, and deterioration of the fixing unit can be effectively suppressed. Here, the predetermined thickness may be set in advance by experiments or the like as a lower limit value of the thickness of the print medium that can be peeled off from the fixing unit without using a peeling member, for example.

  In the image printing apparatus of the present invention, the width of the peeling member may be substantially the same as or larger than the width of the printing medium. By so doing, it is possible to more reliably peel the print medium from the fixing means.

The image printing method of the present invention includes:
An image printing method by computer software for printing an image on a print medium,
A fixing means for fixing the toner image on the surface of the print medium by sending the print medium while being pressed against the surface of the print medium on which the toner image is transferred; and a front end of the print medium sent by the fixing means A peeling member capable of taking a first posture in contact with a position where the fixing member can be peeled off and a second posture separating from the fixing means, and the peeling member as the first posture or the second posture. And positioning means for positioning in the posture of
(A) placing the peeling member in the first posture by the positioning means when the printing medium is sent out while being pressed by the fixing means;
(B) after the leading edge of the printing medium is peeled off from the fixing means in the step (a), the step of bringing the peeling member into the second posture by the positioning means;
Is included.

  In this image printing method, when the print medium is sent out while being pressed against the fixing means, the positioning member is operated to position the peeling member in the first posture. Therefore, the leading edge of the printing medium is easily separated from the fixing means by the peeling member. Peel off. On the other hand, since the positioning member is operated to position the peeling member in the second posture after the front end of the printing medium is peeled off from the fixing unit, the peeling member does not wear or damage the fixing unit. Thus, by bringing the peeling member into contact with the fixing means only when necessary, the deterioration of the fixing means can be suppressed and the product life can be extended as compared with the case where the peeling member is always kept in contact with the fixing means. Also, if the peeling member is brought into contact with the fixing means, the peeling member can easily enter between the fixing means and the printing medium as compared with the case where the peeling member and the fixing means are not in contact with each other. Can be reliably peeled off. In addition, you may add the step which implement | achieves the function of any of the image printing apparatus mentioned above to the image printing method of this invention.

  The image printing program of the present invention is a program for causing one or more computers to execute each step of the above-described image printing method. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.), or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. If this program is executed by a single computer or each step is shared and executed by a plurality of computers, the same effect as the above-described image printing method can be obtained.

  FIG. 1 is a block diagram showing a schematic configuration of a color laser printer 10 according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a schematic configuration of a printer mechanism 31 of the color laser printer 10, and FIG. It is a block diagram which shows schematic structure.

  As shown in FIG. 1, the color laser printer 10 of this embodiment includes a controller 20 that controls the entire apparatus, an electrophotographic printer mechanism 31, and a printer ASIC 32 that controls the printer mechanism 31. The printer unit 30, a fixing unit 68 that melts and fixes the toner image transferred to the paper P in the printer mechanism 31, and the paper P is peeled from the heat roller 73 provided in the vicinity of the heat roller 73 of the fixing unit 68. The separation claw 70 and an operation panel 44 for inputting instructions by the user and displaying various information are provided. Note that “ASIC” is an abbreviation for Application Specific Integrated Circuit.

  The controller 20 is configured as a microprocessor centered on the CPU 21, and is electrically rewritable with a ROM 22 that stores various processing programs and a RAM 23 that temporarily stores data and stores data. A flash memory 24 that retains data even when the power is turned off and a job memory 25 that stores a print job are provided. The controller 20 is electrically connected to the printer ASIC 32, the operation panel 44, the first and second detection sensors 75 a and 75 b, and the solenoid 71 that moves the separation claw 70 via the bus 27, and print command signals to the printer ASIC 32 and the like. A display command signal to the operation panel 44 and a control signal to the solenoid 71 are output, a printing operation signal from the printer ASIC 32, various command signals from the operation panel 44, and detection signals from the first and second detection sensors 75a and 75b. Enter. The controller 20 also exchanges signals with a plurality of computers 51 to 53 connected to a network (for example, a telecommunication network such as a local area network) via the network board 27. That is, the controller 20 inputs a print job and various command signals from each of the computers 51 to 53 and outputs status information of the print job being processed to the computers 51 to 53 that are the transmission source of the print job.

  The printer unit 30 includes a printer mechanism 31 and a printer ASIC 32. As shown in FIG. 2, the printer mechanism 31 is configured as a full-color electrophotographic printer mechanism that employs a single photoreceptor system and an intermediate transfer system, and has cyan (C) and magenta (C) on the charged surface. M), yellow (Y), black (K), and a photosensitive member 63 on which an electrostatic latent image of an image for each color separated into four colors is formed by an exposure device 62, and toner cartridges 40C, 40M, The toner 61 of each color supplied from 40Y and 40K is attached to the electrostatic latent image formed on the photosensitive member 63 and developed as a toner image, and primary transfer is performed so that the developed toner images of each color are superimposed. A secondary belt that secondary-transfers a four-color toner image formed on the transfer belt 64 to a transfer belt 64 as an intermediate transfer member and a sheet P transported from a sheet cassette 65 by a transport unit 66. A shooting unit 67, and a fixing unit 68 for melting and fixing the toner images of four colors have been transferred onto the sheet P to the paper P, a paper discharge tray 69 for storing the sheet discharged P. Among these, the developing device 61 is rotated so that the mounted toner cartridges 40C, 40M, 40Y, and 40K face the photoconductor 63, respectively. The exposure device 62 exposes the photoconductor 63 with a laser beam scanned by a polygon mirror that is rotationally driven by a motor to form an electrostatic latent image. On the other hand, the printer ASIC 32 is an IC chip having a function of controlling the printer mechanism 31, and development data obtained by developing a print job stored in the job memory 25 into a bitmap image for each page is printed on the paper P. The printer mechanism 31 is controlled.

  As shown in FIG. 3, the fixing unit 68 includes a cylindrical metal core 73 b having a heater 73 a at the center and a rubber layer 74 c formed on the outer periphery of the metal core 73 b and comes into contact with the toner image on the paper P. The heat roller 73 and an elastic layer 74b that is softer than the rubber layer 73c of the heat roller 73 are formed on the outer periphery of the metal shaft 74a. The pressure roller 74 is in pressure contact with the heat roller 73 by a biasing force of a spring (not shown). ing. Among these, the heat roller 73 is connected to a motor (not shown) and is driven to rotate by this motor. The pressure roller 74 is driven to rotate in a direction opposite to the rotation due to friction with the heat roller 73 generated as the heat roller 73 rotates. When the heat roller 73 is rotationally driven when the paper P is supplied from the secondary transfer unit 67 to the fixing unit 68, the pressure roller 74 is driven and rotated by the rotation of the heat roller 73. Then, the paper P is conveyed downstream while being sandwiched between the heat roller 73 and the pressure roller 74. At this time, since the heat roller 73 is heated by the heater 73 a, the toner melted by the heat is pressed against the paper P by the pressure of the heat roller 73 and the pressure roller 74. As a result, the toner image on the surface of the paper P is fixed on the paper P. After fixing, the paper P is peeled off from the heat roller 73 and carried out toward the paper discharge tray 69. Since the rubber layer 74 c of the heat roller 73 is harder than the elastic layer 74 b of the pressure roller 74, the paper P is easily peeled off from the heat roller 73 due to the nip pressure generated between the heat roller 73 and the pressure roller 74. ing. Further, a first detection sensor 75a and a second detection sensor 75b for detecting the presence or absence of the paper P are disposed in the vicinity of the upstream side and the downstream side of the heat roller 73, respectively. The detection sensors 75a and 75b are contact type micro switch sensors, and output a detection signal when the leading end portion of the paper P passes through the detection sensors 75a and 75b.

  As shown in FIG. 3, the separation claw 70 has a predetermined small distance from the position Q immediately after the sheet P is released from the pressure contact between the heat roller 73 and the pressure roller 74 among the positions facing the heat roller 73. One (for example, several mm to several cm) is provided on the downstream side. The separation claw 70 is a thin plate having a thin and sharp shape in which the front end portion close to the heat roller 73 is covered with an elastic film, and the width thereof is substantially the same as the width of the surface of the heat roller 73 that contacts the paper P. Yes. For this reason, when the separation claw 70 and the paper P come into contact, the separation claw 70 comes into contact with the entire width of the paper P. The separation claw 70 is movable by a solenoid 71. That is, when the solenoid 71 is not energized, the separation claw 70 is separated from the heat roller 73 by a small distance (for example, several mm), and when the solenoid 71 is energized, the separation claw 70 contacts the heat roller 73.

  The operation panel 44 displays various input buttons 46 such as a numeric keypad and cursor keys capable of inputting an instruction from the user, characters and numbers associated with the key operation, and processing statuses in the controller 20 and the printer unit 30. Liquid crystal screen 45.

  Next, functions of the color laser printer 10 of the present embodiment configured as described above, particularly, a procedure for performing printing on the paper P will be described. When the CPU 21 of the controller 20 receives a print job from any of the computers 51 to 53 connected via the network, the print job is stored in the job memory 25 and a print command is output to the printer ASIC 32 of the printer unit 30. To do. When this print command is input, the printer ASIC 32 executes a print processing routine shown in FIG.

  When this print processing routine is started, the CPU 21 of the controller 20 first develops one page of the print job in the job memory 25 into a bitmap image and performs color separation into four colors of yellow, magenta, cyan, and black. (Step S100). Subsequently, it is determined whether or not the number of dots D in the leading edge region of the paper P (for example, a region several centimeters from the leading edge of the paper P) in the bitmap image of the page to be printed this time is larger than the allowable dot number Dth. (Step S102). Here, the allowable number of dots Dth is a value set in advance through experiments or the like as the upper limit of the number of dots that can be peeled from the heat roller 73 by the nip pressure during fixing. When the number of dots D in the front end region of the paper P is larger than the allowable number of dots Dth, a value 1 is set to the contact flag Fs (step S104). Here, the contact flag Fs is a flag indicating whether or not the separation claw 70 is brought into contact with the heat roller 73. When the value is zero, the separation claw 70 is not brought into contact with the heat roller 73. This means that the nail 70 is brought into contact with the heat roller 73.

  When the number of dots D in the leading end region of the paper P is equal to or smaller than the allowable number of dots Dth in step S102 or after the value 1 is set to the contact flag Fs in step S104, the CPU 21 feeds paper from the paper cassette 65 by the transport unit 66. Then, the paper P is conveyed toward the secondary transfer unit 67 (step S106). Subsequently, an electrostatic latent image is formed on the surface of the photoconductor 63 by the exposure device 62 based on an image image of any one color (for example, yellow) among the image images obtained by charging the surface of the photoconductor 63 and then performing color separation. The yellow toner that is formed and supplied from the toner cartridge 40Y is attached to the electrostatic latent image on the photosensitive member 63 to develop the toner image, and the developed yellow toner image is primarily transferred to the transfer belt 64 (step S108). . Thereafter, the developing device 61 is sequentially rotated, and charging, exposure, development, and primary transfer are performed in the same manner for the other three colors. When the primary transfer is completed for all colors, a four-color toner image is formed on the transfer belt 64 by sequentially superimposing the toner images of the respective colors.

  When the primary transfer is completed, the CPU 21 secondarily transfers the superposed toner image on the transfer belt 64 to the paper P while conveying the paper P by the secondary transfer unit 67 (step S110). As a result, four color toners adhere to the surface of the paper P.

  When the secondary transfer is completed and the paper P is conveyed from the secondary transfer unit 67 to the fixing unit 68, the CPU 21 rotates the heat roller 73 to rotate the paper P between the heat roller 73 and the pressure roller 74. The operation of fusing and fixing the four color toner images sandwiched and secondarily transferred onto the paper P is started (step S112). At this time, the heat roller 73 is already heated by the heater 73a. Subsequently, it is determined whether or not the contact flag Fs is a value 1 (step S114). When the contact flag Fs is a value 1, it is determined whether or not the contact start timing T for bringing the separation claw 70 into contact with the heat roller 73 has been reached. (Step S116). The contact start timing T is set based on a detection signal from the first detection sensor 75a. That is, the time until the leading edge of the paper P reaches the position Q (see FIG. 3) immediately after being released from the pressure contact between the heat roller 73 and the pressure roller 74 after passing through the first detection sensor 75a is the conveyance time t. The contact start timing T is defined as the point in time when the conveyance time t has elapsed after the detection signal is output from the first detection sensor 75a. In the present embodiment, the transport speed for transporting the paper P from the first detection sensor 75a to the position Q is substantially the same for printing one page. If the contact start timing T is not reached in step S116, the process waits until the contact start timing T is reached. When the leading edge of the paper P reaches the position Q and reaches the contact start timing T, the solenoid 71 is energized and separated. The nail | claw 70 is made to contact the heat roller 73 (step S118). That is, when the leading edge of the paper P reaches the position Q, the separation claw 70 contacts the heat roller 73.

  Subsequently, the CPU 21 determines whether or not the detection signal from the second detection sensor 75b has been input (step S120). When the detection signal has not yet been input from the second detection sensor 75b, the CPU 21 heats the separation claw 70. Leave in contact with roller 73. As described above, when the detection signal is not output from the second detection sensor 75b, the leading end of the sheet P is in close contact with the heat roller 73, or the leading end of the sheet P is not yet conveyed to the second detection sensor 75b. Is mentioned. On the other hand, when the detection signal is input from the second detection sensor 75 b, it is determined that the leading edge of the paper P is peeled off from the heat roller 73, the energization to the solenoid 71 is stopped, and the separation claw 70 is separated from the heat roller 73. At the same time, the contact flag Fs is reset to zero (step S122).

  When the contact flag Fs is zero in step S114 or after the separation claw 70 is separated from the heat roller 73 in step S122, the CPU 21 discharges the fixed sheet P to the discharge tray 69 (step S124). Thereafter, it is determined whether or not there are pages to be printed (step S126). When there are pages to be printed, the process returns to step S100, and when there are no pages to be printed, this routine is terminated.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The fixing unit 68 of this embodiment corresponds to the fixing unit of the present invention, the separation claw 70 corresponds to the peeling member, and the solenoid 71 corresponds to the positioning unit. Further, the CPU 21 of the controller 20 corresponds to the control means, the first detection sensor 75a corresponds to the position detection means, the second detection means 75b corresponds to the peeling detection means, and the network board 27 corresponds to the input means. In this embodiment, an example of the image printing method of the present invention is also clarified by describing the operation of the color laser printer 10.

  According to the color laser printer 10 of the present embodiment described in detail above, the separation claw 70 is brought into contact with the heat roller 73 at a timing immediately after the leading edge of the paper P is released from the pressure contact between the heat roller 73 and the pressure roller 74. . As a result, the leading edge of the separation claw 70 enters between the paper P and the heat roller 73, so that the leading edge of the paper P is easily separated from the heat roller 73 by the separation claw 70. Further, when the position detection sensor 75b detects that the leading edge of the paper P is peeled off from the heat roller 73, the separation claw 70 no longer needs to be in contact with the heat roller 73. 70 is separated. Thereby, since the separation claw 70 and the heat roller 73 are not in contact with each other, the separation claw 70 does not wear or damage the heat roller 73. In this way, by bringing the separation claw 70 into contact with the heat roller 73 only when necessary, the deterioration of the heat roller 73 can be suppressed and the product life can be extended compared to the case where the separation claw 70 is kept in contact with the heat roller 73 at all times. can do. Further, if the separation claw 70 is brought into contact with the heat roller 73, the tip of the separation claw 70 can easily enter between the heat roller 73 and the paper P, compared to the case where the separation claw 70 and the heat roller 73 are not in contact with each other. Therefore, the paper P can be reliably peeled from the heat roller 73.

  Further, since the operation of bringing the separation claw 70 into contact with or separating from the heat roller 73 is performed by the CPU 21 energizing or de-energizing the solenoid 71, a complicated operation by the user is not required.

  Furthermore, since the timing at which the separation claw 70 is brought into contact with the heat roller 73 is set based on the position of the paper P detected by the first detection sensor 75a, the paper is moved to a position where the separation between the paper P and the heat roller 73 is necessary. The separation claw 70 can be brought into contact with the heat roller 73 when P is sent out.

  Furthermore, since it is determined whether or not the leading edge of the sheet P has been peeled off from the heat roller 73 based on the presence or absence of a detection signal from the second detection sensor 75b, it is possible to accurately grasp that the leading edge of the sheet P has been peeled off from the heat roller 73. be able to. Therefore, the separation claw 70 is not brought into contact with the heat roller 73 more than necessary.

  Since the separation claw 70 is brought into contact with the heat roller 73 when the number of dots D in the front end region of the paper P is larger than the allowable number of dots Dth, the paper P can be reliably peeled from the heat roller 73. Further, when the number of dots D in the leading end region of the paper P is equal to or less than the allowable number of dots Dth, the separation claw 70 is not brought into contact with the heat roller 73 even when the paper P is peeled off from the heat roller 73. Can be effectively suppressed.

  Further, when the separation claw 70 and the paper P are in contact with each other, the separation claw 70 is in contact with the entire width of the paper P, so that the paper P is heated by the heat roller 73 as compared with the case where the separation claw 70 is in contact with a part of the paper P. Can be reliably peeled off.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the printing processing routine of the above-described embodiment, whether or not the separation claw 70 is brought into contact with the heat roller 73 is determined based on the dot number D of the leading end region of the paper P in step S110. Further, it may be determined whether or not the separation claw 70 is brought into contact with the heat roller 73 on the basis of the margin amount R on the leading end side of the paper P. For example, the print processing routine of FIG. 5 may be executed. In FIG. 5, the same processes as those in FIG. 4 are denoted by the same step numbers as those in FIG. When the print processing routine of FIG. 5 is started, the CPU 21 executes the process of step S100, and then performs a margin amount R in a predetermined area on the front end side of the paper P (for example, an area several centimeters from the front end side of the paper P). Is less than the first margin amount R1 (step S202). Here, the margin amount R is determined from the information regarding the margin of the paper P included in the print data transmitted from the computers 51 to 53. The information regarding the margin is created by setting a margin amount or specifying borderless printing on a print instruction screen in which the user instructs printing. Further, the first margin amount R1 is a value set in advance through experiments or the like as a lower limit value (for example, several millimeters from the front end of the sheet P) of the margin amount necessary for peeling the sheet P from the heat roller 73 by the nip pressure. is there. Note that the margin amount R is zero during borderless printing. Thereafter, the processing of steps S104 to S126 is executed, and this routine is terminated. In this way, the separation claw 70 can be brought into contact with the heat roller 73 when the paper P easily adheres to the heat roller 73 based on the margin amount on the leading end side of the paper P. In addition, when the margin amount is zero, that is, in the case of borderless printing, the tip of the paper P is easily adhered to the heat roller 73 by adhering the toner to every corner of the paper P. By contacting the roller 73, the paper P can be reliably peeled from the heat roller 73.

  In the printing processing routine of the above-described embodiment, whether or not the separation claw 70 is brought into contact with the heat roller 73 may be determined based on the number of dots D on the leading end side of the paper P and the margin amount R. For example, the print processing routine of FIG. 6 may be executed. In FIG. 6, the same processes as those in FIG. 4 are denoted by the same step numbers as in FIG. When the print processing routine of FIG. 6 is started, the CPU 21 executes the process of step S100, and then the margin amount R in the first area at the leading edge of the paper P (for example, an area several millimeters from the leading edge of the paper P) is calculated. It is determined whether or not the amount is smaller than the second margin amount R2 (step S302). This second margin amount may be the same value as or different from the first margin amount R1 in the print processing routine of FIG. When the margin amount R is smaller than the predetermined margin amount Rth, the processing of steps S104 to S126 is executed and this routine is terminated. On the other hand, when the margin amount R is equal to or greater than the second margin amount R2, whether or not the number of dots D in the second region on the leading end side of the paper P (for example, a region of several centimeters in contact with the first region) is greater than the allowable number of dots Dth. Is determined (step S304). Then, when the number of dots D in the second region is larger than the allowable number of dots Dth, the processing after step S104 is executed, and when the number of dots D is equal to or less than the allowable number of dots Dth, processing after step S106 is executed. Exit. In this way, the separation claw 70 is brought into contact with the heat roller 73 when there is an image with a high degree of toner adhesion following the blank area on the leading end side of the paper P, so that the same effect as in the above-described embodiment can be obtained. It is done.

  In the embodiment described above, whether or not the separation claw 70 is brought into contact with the heat roller 73 may be determined according to the type of the paper P. Specifically, the print processing routine of FIG. 7 may be executed. In FIG. 7, the same processes as those in FIG. 4 are denoted by the same step numbers as those in FIG. When the print processing routine of FIG. 7 is started, the CPU 21 first executes steps S100 and S102. When the number of dots D is less than or equal to the allowable number of dots Dth in step S102, the type of paper P currently being printed is determined (step S402), and when the type is a predetermined thin paper, the processing from step S104 is executed. Here, the type of the paper P currently being printed is determined by reading out information on the type of the paper P included in the print data. This information is created based on the type of paper P selected on the print instruction screen for the user to instruct printing. Further, the predetermined thin paper is a paper (for example, a trace paper) that has a small thickness and is easily adhered to the heat roller 73. On the other hand, when the type of the paper P currently being printed is not a predetermined thin paper, the processing after step S106 is executed and this routine is terminated. By doing so, the separation claw 70 can be brought into contact with the heat roller 73 when the paper P is easily in close contact with the heat roller 73 because the thickness of the paper P is thin. At this time, as the type of the paper P, instead of or in addition to the thickness of the paper, for example, the separation claw 70 is attached to the heat roller 73 based on the property, material, size, etc. of the surface of the printing medium such as flatness and wetness. It may be determined whether or not to make contact.

  In the above-described embodiment, the separation claw 70 is separated from the heat roller 73 when the detection signal from the second detection sensor 75 b is input. However, based on the time that has elapsed since the separation claw 70 was brought into contact with the heat roller 73. The separation claw 70 may be separated from the heat roller 73. In this way, it is possible to grasp that the leading edge of the paper P has been peeled off from the heat roller 73 without providing a new detection means for detecting that the leading edge of the paper P has peeled off from the heat roller 73. However, it is preferable to dispose the second detection sensor 75b in order to more accurately grasp that the leading edge of the paper P has been peeled off from the heat roller 73.

  In the above-described embodiment, a thin plate having a thin and sharp tip is used as the peeling member. However, the present invention is not limited to this, for example, using a member having a plurality of teeth and pins at the tip. Also good. Further, although the separation claw 70 is capable of contacting the entire width of the paper P, it may be one that can contact a part of the width of the paper P.

  In the embodiment described above, the separation claw 70 contacts the heat roller 73 by energizing the solenoid 71 and is separated from the heat roller 73 by stopping energization of the solenoid 71, but the present invention is not limited to this. For example, the separation claw 70 may be brought into contact with or separated from the heat roller 73 by a motor.

  In the above-described embodiment, a roller fixing method in which fixing is performed using the heat roller 73 and the pressure roller 74 is employed. However, the present invention is not limited to this, and for example, one or two fixing belts are used. Alternatively, a belt fixing method in which fixing is performed may be employed. In this case, for example, the separation claw 70 is disposed in the immediate vicinity of the position where the paper P is released from the pressure contact with the fixing belt.

  In the above-described embodiment, the single photoreceptor system and the intermediate transfer system are employed as the printer mechanism 31. However, the present invention is not limited to this, and for example, a direct transfer system that directly transfers from the photoreceptor to the paper P. Or a tandem method including a photoconductor for each color may be employed.

  In the above-described embodiment, the present invention is applied to the color laser printer 10, but the present invention is not limited to this. For example, the present invention is applied to an electronic apparatus having a printing function such as a facsimile machine, a copier, and a multifunction machine. You may apply.

1 is a block diagram showing a schematic configuration of a color laser printer 10. FIG. 1 is a configuration diagram showing a schematic configuration of a color laser printer 10. FIG. FIG. 3 is a configuration diagram showing a schematic configuration of a fixing unit 68. 6 is a flowchart of a print processing routine. 10 is a flowchart of another print processing routine. 10 is a flowchart of another print processing routine. 10 is a flowchart of another print processing routine.

Explanation of symbols

  10 color laser printer, 20 controller, 21 CPU, 22 ROM, 23 RAM, 24 flash memory, 25 job memory, 26 network board, 27 bus, 30 printer unit, 31 printer mechanism, 32 printer ASIC, 40C, 40M, 40Y, 40K toner cartridge, 51 to 53 computer, 61 developing device, 62 exposure device, 63 photoconductor, 64 transfer belt, 65 paper cassette, 66 transport unit, 67 secondary transfer unit, 68 fixing unit, 69 paper discharge tray, 70 separation Claw, 71 Solenoid, 73 Heat roller, 73a Heater, 73b Metal core, 73c Rubber layer, 74 Pressure roller, 74a Shaft, 74b Elastic layer, 75a First detection sensor, 75b Second detection sensor.

Claims (14)

An image printing apparatus for printing an image on a print medium,
Fixing means for fixing the toner image to the surface of the print medium by sending out the print medium while being pressed against the print medium having the toner image transferred on the surface;
A peeling member capable of taking a first posture in which the front end of the print medium sent out by the fixing unit comes into contact with a position where the leading end can be peeled off from the fixing unit and a second posture separated from the fixing unit;
Positioning means for positioning the peeling member in the first posture or the second posture;
An image printing apparatus comprising: The image printing apparatus according to claim 1,
When the printing medium is sent out from the fixing means by the fixing means, the positioning means is controlled so that the peeling member takes the first posture, and after the leading edge of the printing medium is peeled off from the fixing means, Control means for performing positioning control for controlling the positioning means so that the peeling member takes the second posture;
An image printing apparatus comprising: The image printing apparatus according to claim 2,
Position detecting means for detecting the position of the print medium;
With
In executing the positioning control, the control means moves the peeling member from the second posture based on the position of the print medium detected by the position detection means when the print medium is sent out from the fixing means. Determining the timing to change to the first posture, and controlling the positioning means so that the peeling member takes the first posture at the determined timing;
Image printing device. The image printing apparatus according to claim 2 or 3,
A peeling detection means for detecting whether or not the front end of the printing medium has been peeled off from the fixing means;
With
In performing the positioning control, the control unit is configured so that the peeling member takes the second posture after the peeling detecting unit detects that the leading edge of the printing medium is peeled from the fixing unit. Controlling the positioning means;
Image printing device. In executing the positioning control, the control means determines whether or not the leading edge of the print medium has been peeled from the fixing means based on a time elapsed since the peeling member took the first posture. The positioning means is controlled so that the peeling member takes the second posture after it is determined that the leading edge of the printing medium has peeled from the fixing means;
The image printing apparatus according to claim 2 or 3. The image printing apparatus according to any one of claims 2 to 5,
Input means for inputting image data;
With
The control means determines whether to execute the positioning control based on the image data input to the input means;
Image printing device. The control means grasps a margin amount in a predetermined area on the leading end side of the print medium from the image data, and executes the positioning control when the grasped margin amount is smaller than a predetermined margin amount;
The image printing apparatus according to claim 6. The control means executes the positioning control at the time of marginless printing in which the margin amount is small or substantially zero.
The image printing apparatus according to claim 7. The control means detects the degree of toner adhesion in a predetermined region on the front end side of the print medium from the image data, and executes the positioning control when the detected degree of toner adhesion is greater than a predetermined degree. To
The image printing apparatus according to claim 6. The control means determines whether to execute the positioning control based on a type of the print medium;
The image printing apparatus according to claim 2. The control means executes the positioning control when the print medium is thinner than a predetermined thickness;
The image printing apparatus according to claim 10. The peeling member has a width substantially equal to or larger than the width of the print medium,
The image printing apparatus according to claim 1. An image printing method by computer software for printing an image on a print medium,
A fixing means for fixing the toner image on the surface of the print medium by sending the print medium while being pressed against the surface of the print medium on which the toner image is transferred; and a front end of the print medium sent by the fixing means A peeling member capable of taking a first posture in contact with a position where the fixing member can be peeled off and a second posture separating from the fixing means, and the peeling member as the first posture or the second posture. And positioning means for positioning in the posture of
(A) placing the peeling member in the first posture by the positioning means when the printing medium is sent out while being pressed by the fixing means;
(B) after the leading edge of the printing medium is peeled off from the fixing means in the step (a), the step of bringing the peeling member into the second posture by the positioning means;
An image printing method including:   An image printing program for causing one or more computers to execute each step of the image printing method according to claim 13.

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