JP2005345531A - Image forming apparatus - Google Patents

Image forming apparatus Download PDF

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Publication number
JP2005345531A
JP2005345531A JP2004161934A JP2004161934A JP2005345531A JP 2005345531 A JP2005345531 A JP 2005345531A JP 2004161934 A JP2004161934 A JP 2004161934A JP 2004161934 A JP2004161934 A JP 2004161934A JP 2005345531 A JP2005345531 A JP 2005345531A
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Prior art keywords
information
recording paper
fixing
speed information
unit
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JP2004161934A
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Japanese (ja)
Inventor
Masahiro Sonoda
真宏 園田
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Oki Data Corp
株式会社沖データ
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Priority to JP2004161934A priority Critical patent/JP2005345531A/en
Publication of JP2005345531A publication Critical patent/JP2005345531A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To prevent transfer failures caused by a difference between the recording paper conveyance speed of a fixing section and the conveyance speed of an image forming section due to the difference in the peripheral speeds of fixing members of the fixing section and the difference in recording paper widths, and to prevent malfunction of a drive mechanism including a motor, which is caused by large load on the drive motor used for driving the fixing member of the fixing section. <P>SOLUTION: The image forming apparatus includes a transfer section for transferring a toner image to recording paper of an arbitrary size that is conveyed; and the fixing section for heating and fixing the toner image onto the recording paper conveyed from the transfer section and also the fixing section having the driving part for rotating the fixing member. The image forming apparatus is provided with a width-size information acquiring means for acquiring the width-size information, showing recording paper width size, and speed information determining means. The speed information determining means determines the speed information of the fixing section, on the basis of the width size information acquired by the width-size information acquiring means, set speed information showing the preset conveyance speed of the recording paper, and set width size information showing the width size made to correspond to the set speed information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus capable of controlling the conveyance speed of a recording sheet of a fixing unit that fixes a toner image on the recording sheet.

  There is known an image forming apparatus that prints image data on a recording paper of an arbitrary size such as a standard paper or a long paper. The image forming apparatus as described above includes a paper feed unit or a multi-purpose tray that feeds recording paper. When a recording paper of an arbitrary size is set, the width of the set recording paper is detected. . (See Patent Document 1 below)

  In this image forming apparatus, for example, when image data based on the width dimension of a predetermined recording sheet is received from a host apparatus, a sheet feeding unit or a multipurpose paper in which the recording sheet having a width dimension to be printed is set. The tray is selected, the recording paper is fed, a toner image based on the received image data is formed by the image forming unit, and the formed toner image is transferred to the recording paper by the transfer unit. Is conveyed to the fixing unit.

  The fixing unit takes in the recording paper on which the toner image is transferred, fixes the toner image on the recording paper, and sends the recording paper to the discharge unit.

  The fixing unit includes a fixing roller 11 and a pressure roller 12 as fixing members as shown in FIG.

  Energizing members are provided at both ends of the pressure roller 12 to press against the fixing roller 11, and the recording paper is conveyed by the rotation of both rollers 11 and 12. By the way, when the pressure roller is formed in a cylindrical shape, both ends of the pressure roller 12 are pressed with a large force by the urging members at both ends thereof, so that the center portion is bent and the pressure roller 12 is subjected to an application to the fixing roller 11. The nip pressure at the central portion of the pressure roller 12 becomes smaller than both end portions. Therefore, fixing unevenness may occur in the transferred toner image due to the difference in nip pressure.

Therefore, in order to prevent the above-described uneven fixing of the toner image, as shown in FIG. 2, the central portion of the pressure roller 12 has a larger diameter than both ends, and is formed in a drum shape. The nip pressure at the center and both ends of the pressure roller 12 is kept uniform.
JP 2003-11466 A

  However, the image forming apparatus as described above has the following problems to be solved. That is, in the fixing unit, when the peripheral speed at the center of the fixing member is different from the peripheral speed at both ends, the recording paper transport speed of the fixing section may be slower than the transport speed of the transfer section for recording paper with a small width. Due to the speed difference, the recording paper may bend between the fixing unit and the transfer unit, and may come into sliding contact with the surrounding mechanism unit and the unfixed toner may be peeled off. On the other hand, in the case of recording paper having a large width, the conveyance speed of the fixing unit is faster than the conveyance speed of the transfer unit, so that the recording paper may be pulled by the fixing unit. A large load is applied to the drive motor for driving the motor, which may cause a failure of the drive mechanism including the motor.

The present invention adopts the following configuration in order to solve the above points.
<Configuration 1>
A transfer unit that transfers a toner image to a recording paper of an arbitrary size that is conveyed, a fixing member that heat-fixes the toner image on the recording paper that is conveyed from the transfer unit, and a drive that rotationally drives the fixing member A fixing unit having a section, a width dimension information acquiring unit that acquires width dimension information indicating a width dimension of the recording sheet, and transporting the recording sheet corresponding to the width dimension information acquired by the width dimension information acquiring unit Speed information determining means for determining speed information and speed control means for controlling the drive unit based on the transport speed information are provided.
<Configuration 2>
In the image forming apparatus according to Configuration 1, the fixing member includes a fixing roller and a pressure roller, and is formed in a drum shape in which an outer diameter of a central portion of the pressure roller is larger than both end portions. And
<Configuration 3>
In the image forming apparatuses according to Configuration 1 and Configuration 2, the fixing member is configured by a belt wound around the pressure roller.
<Configuration 4>
In the image forming apparatus according to Configuration 1, the speed information determination unit is based on the following formula:
t = t0 × (1 + γ (W−W0)) | (where t: transport speed information, t0: reference transport speed information set as a reference in advance, γ (> 0): width coefficient, W: acquired width dimension) Information, W0: Reference width dimension information set in advance as a reference) The conveyance speed information for conveying the recording paper of the drive unit is determined.
<Configuration 5>
In the image forming apparatus according to Configuration 1, the speed information determination unit includes a speed information correspondence table in which conveyance speed information is associated with each preset width dimension information, and is based on the acquired width dimension information of the recording paper. Then, by referring to the speed information correspondence table, transport speed information for transporting the recording paper of the drive unit is determined.
<Configuration 6>
A transfer unit that transfers a toner image to a recording paper of an arbitrary size that is conveyed, a fixing member that heat-fixes the toner image on the recording paper that is conveyed from the transfer unit, and a drive that rotationally drives the fixing member In an image forming apparatus including a fixing unit having a unit, a speed information correspondence table in which recording sheet conveyance speed information is associated with each image density information indicating a ratio of the number of dots of an image, and one page of recording paper in image data Image density information acquisition means for calculating the image density information of the image data based on the number of image dots and the reference image dot number and the reference image density set in advance as a reference; Speed information that determines recording sheet conveyance speed information of the drive unit by referring to the speed information correspondence table based on the acquired image density information Based on the conveyance speed information the determined constant section, characterized in that it comprises a speed control means for controlling the drive unit.

  According to the image forming apparatus of the present invention, the width dimension information indicating the width dimension of the recording sheet is acquired for the recording sheet conveyed from the transfer unit to the fixing unit, and the recording sheet corresponding to the acquired width dimension information is acquired. Since the drive unit is controlled based on the transport speed information, the recording unit can transport the recording sheet at a desired transport speed by the fixing unit even if the recording sheets have different widths. Can do. Therefore, it is possible to prevent a transfer failure from occurring on the recording paper and a large load from being applied to the drive motor for driving the fixing unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a schematic configuration diagram of the image forming apparatus according to the first embodiment.

  The image forming apparatus according to the first embodiment includes a paper feeding unit 1, an image forming unit 140, a transfer unit 180, a fixing unit 190, and a recording paper information detection sensor 120 (S1, S2, S3), and a Centronics cable. It can be connected to a host device such as a PC with a USB cable and a network cable.

  The paper feeding unit 1 is configured by a paper feeding tray or a multi-purpose tray. When a recording paper is fed from the paper feeding unit 1, the recording paper information detection sensor 120 records the paper fed as described later. Output paper detection signal.

  Based on image data, the image forming unit 140 includes cyan, magenta, yellow, and black photosensitive drums 3, 4, 5, and 6, a charging unit that charges each photosensitive drum, and each charged photosensitive drum based on image data. An exposure unit that exposes the head to form an electrostatic latent image, and a developing unit that forms a toner image by attaching toner to the electrostatic latent image formed by the exposure unit. And a driving unit for driving the photosensitive drums 3, 4, 5, and 6, a charging unit, and a developing unit.

  A transfer unit 180 is disposed below the image forming unit 140. The transfer unit 180 includes a plurality of transfer rollers 8, a transport belt 9, and a transport drive motor (not shown) that drives a drive roller around which the belt is wound.

  The transfer unit 180 is formed on each color photosensitive drum 3, 4, 5, 6 of the image forming unit 140 by driving the transport driving motor to operate the transport belt 9 and applying a transfer voltage to the transfer roller 8. The transferred toner image is transferred onto the recording paper on the conveying belt 9 and the toner-formed recording paper on which the toner image has been transferred is conveyed toward the fixing unit 190.

  The fixing unit 190 measures a fixing roller 11 as a fixing member, a pressure roller 12, a heater for heating the fixing roller 11, a power source for supplying power to the heater, and a surface temperature of the fixing roller 11. And a fixing drive motor 190A (see FIG. 1).

  FIG. 2 is a diagram showing the shapes of both rollers constituting the fixing unit 10. In order to prevent fixing unevenness in the transferred toner image due to the difference in nip pressure, the central portion of the pressure roller 12 is made larger in diameter than both ends as shown in FIG. Thus, the nip pressure at the center and both ends of the pressure roller 12 with respect to the fixing roller 11 is kept uniform.

  The fixing roller 11 is rotationally driven by a fixing drive motor 190A through a gear train (not shown) provided at both ends thereof. The pressure roller 12 is also provided with gear trains at both ends, and the gear train of the pressure roller 12 meshes with the gear train of the fixing roller 11. Accordingly, the pressure roller 12 is also driven to rotate together with the fixing roller 11.

  The heater is pressure controlled based on the surface temperature information of the fixing roller 11 by the thermistor, whereby the surface temperature of the fixing roller 11 is maintained constant.

  When the toner-formed recording paper is conveyed from the transfer unit 7, the fixing unit 190 drives the fixing drive motor 190A to rotate the rollers 11 and 12 to take in the toner-formed recording paper and heat the toner image. In addition to fixing, the recording paper is conveyed and discharged to a discharge unit (not shown).

  FIG. 1 is a block diagram of the image forming apparatus according to the first embodiment.

  The image forming apparatus includes an image forming control unit 100, an operation unit 110, the recording paper information detection sensor 120 and the image forming unit 140, a transfer control unit 150 that controls the transfer unit 180, and a speed control unit 160. And the fixing unit 190.

  The operation unit 110 includes an input terminal such as a touch panel and a keyboard and an output terminal such as a liquid crystal panel. Through the output terminal, for example, status information indicating the status of the image forming apparatus such as an error or standby is displayed on the screen. In addition to the display, print instruction information, recording paper information, and the like are received from the user via the input terminal.

  Accordingly, when the image forming apparatus receives the print instruction information from the upper apparatus or the operation unit and the print data from the upper apparatus, the image forming apparatus analyzes the print instruction information and develops the print data based on the analyzed instruction information. Then, the image data is generated and the recording paper is fed from the paper feeding unit 1 to the image forming unit 140.

  As shown in FIG. 5, the recording paper information detection sensor 120 includes a plurality of detection sensors (S 1, S 2, S 3), and is provided between the paper feeding unit 1 and the image forming unit 140. Each of the detection sensors S1, S2, and S3 is located at a position that is half of the width of the recording paper “A4” from the center line of the paper feeding unit 1 indicated by the dotted line on the conveyance path through which the recording paper fed from the paper feeding unit 1 passes. In addition, the detection sensor S1 and the detection sensor S3 are installed at a position half the size of the “A3” recording paper width, and the detection sensor S3 is installed at a position half the size of the “A3 Nobi” recording paper. Accordingly, each of the detection sensors S1, S2, and S3 outputs a detection signal when the recording paper is conveyed from the paper feeding unit 1 and passes over each of the detection sensors.

  The image formation control unit 100 performs overall control in the printing process of the image forming apparatus, and includes a storage unit 170. The storage unit 170 includes a recording sheet information / width dimension information correspondence table 170A in which recording sheet information for specifying a recording sheet is associated with width dimension information indicating the width dimension of the recording sheet, and recording sheet information and detection information. Is associated with the recording paper information / detection information correspondence table 170C.

  FIG. 4 is a diagram showing the recording paper information / width dimension information correspondence table 170A. As shown in FIG. 4, the recording sheet information specifies recording sheets such as “A4” and “A3”, and the width dimension information W1, W2, and W3 indicate the width dimension corresponding to each recording sheet. Yes.

  FIG. 6 is a diagram showing the recording paper information / detection information correspondence table 170C. The recording paper information corresponding to the on (detection) or off detection information of each of the detection sensors S1, S2, and S3 is shown. For example, the detection information indicates that all the detection sensors S1, S2, and S3 are on. In some cases, “A3 Nobi” recording paper is associated as recording paper information. Further, in the case of detection information indicating that the detection sensor S1 is off, all detections are invalid regardless of the outputs of the other sensors S2 and S3, even if a detection failure occurs.

  In addition, the image formation control unit 100 includes a width dimension information acquisition unit 101. The width dimension information acquisition unit 101 acquires the detection information of the recording paper information detection sensor 120, acquires the recording paper information by referring to the recording paper information / detection information correspondence table 170C, or is set from the upper apparatus. The recording sheet information acquired is acquired, or the recording sheet information set from the input terminal of the operation unit 110 is acquired. Then, based on the acquired recording paper information, the recording paper information / width dimension information correspondence table 170A in the storage unit 170 is referred to acquire the width dimension information.

  The fixing drive motor 190A of the fixing unit 190 includes a stepping motor, and the rotation speed is controlled based on the applied pulse period.

  FIG. 7 shows an example of the pulse period set for the fixing drive motor 190A corresponding to the recording sheets of “A4”, “A3”, and “A3 Novi”. For example, when the pulse period T2 corresponding to the width dimension information W2 of the “A3” recording sheet is set as the reference pulse period, the pulse period T3 corresponding to the width dimension information W3 of the “A3 nobi” recording sheet is the reference pulse period. A cycle larger than T2 is set, and a pulse cycle T1 corresponding to the width dimension information W1 of “A4” recording paper is set to a cycle smaller than the reference pulse cycle T2.

  On the other hand, the image formation control unit 100 further includes a speed information determination unit 102. This speed information determining means 102 has a memory 102A, which preliminarily stores reference width dimension information W2, reference speed information t2, and speed calculation formula t = t2 × (1 + γ (W−W2)). keeping. The reference speed information t2 is speed information for outputting the pulse having the period T2. In the speed calculation formula, γ (> 0) is a width coefficient, and the width coefficient γ is a value obtained by an experiment in the design stage.

  Then, the speed information determination unit 102 uses the above formula to calculate the recording paper by the fixing unit 190 based on the width dimension information W, the reference width dimension information W2, and the reference speed information t2 acquired by the width dimension information acquisition unit 101. Is calculated.

  The transfer control unit 150 applies a voltage to the transfer unit 180 to transfer the toner images formed on the plurality of photosensitive drums included in the image forming unit 140 onto the recording paper, and the toner formation recording on which the toner images are transferred. Drive control of a motor for operating a conveyance belt that conveys the paper to the fixing unit 190 is performed.

  When the speed control unit 160 receives the speed information t from the speed information determination unit 102, the speed control unit 160 controls the rotation of the fixing drive motor 190A based on the received speed information t.

  FIG. 8 is an operation flowchart of the image forming apparatus according to the first embodiment.

  By the way, in this embodiment, the conveyance speed of the conveyance belt 9 is set to coincide with the conveyance speed t2 of the recording sheet “A3” of the fixing unit 190.

  In the first embodiment, “A4” recording paper is detected by using the detection sensors S1, S2, and S3 of the recording paper information detection sensor 120, and based on the detected “A4” recording paper, the recording paper information in the storage unit 170 is detected. The width dimension information W1 of the recording paper is specified by referring to the width dimension information correspondence table 170A, the speed information t is calculated by the speed calculation formula, and the obtained speed information t is used as the fixing drive motor 190A of the fixing unit 190. And the conveyance speed of the fixing unit 190 is controlled according to the width dimension of the recording paper by rotating the fixing driving motor 190A according to the speed information t.

  First, when a power switch of an image forming apparatus (not shown) is turned on, the image forming control unit 100 performs a predetermined initialization process based on a control program. At this time, the reference width dimension information W2, speed information t2, and the speed calculation formula are set in the memory 102A of the speed information determination means 102. When the initialization process ends, the image forming apparatus waits until print instruction information and print data are transmitted from the host apparatus.

  When the print instruction information and the print data are received from the upper apparatus, the image formation control unit 100 analyzes the print instruction information and acquires the analysis instruction information. Then, the print data is expanded based on the obtained analysis instruction information to generate image data (step S1).

  Then, the image forming control unit 100 sends the reference speed information t2 to the speed control means 160, and the speed control means 160 supplies a pulse train having a cycle T2 to the fixing drive motor 190A based on the reference speed information t2, and rotationally drives it. (Step S2).

  Further, when the image forming control unit 100 instructs the sheet feeding unit 1 (see FIG. 3) to feed the recording paper and transports the recording paper, the width dimension information acquiring unit 101 causes each of the recording paper information detection sensors 120 to be The detection information indicated by ON and OFF from the detection sensors S1, S2, and S3 is fetched, and based on the fetched detection information, the recording paper information / detection information correspondence table 170C of the storage unit 170 is referred to and recording corresponding to the detection information is performed. Specify paper information.

  In the first embodiment, the detection information of each of the detection sensors S1, S2, and S3 is turned on, off, and off, respectively. Therefore, the width dimension information acquisition unit 101 supports recording paper information and detection information based on the detection information. By referring to the table 170C, “A4” recording paper information is specified.

  Subsequently, the width dimension information acquisition unit 101 refers to the recording sheet information / width dimension information correspondence table 170A based on the specified recording sheet information, acquires the width dimension information W1 corresponding to the recording sheet information, and S3), this width dimension information W1 is transmitted to the speed information determination means 102.

  The speed information determination unit 102 calculates speed information using the speed calculation formula t = t2 × (1 + γ (W1−W2)) and determines the speed information t to be supplied to the speed control unit 160 (step S4). ).

  The speed information determination unit 102 transfers the calculated speed information t = t1 to the speed control unit 160.

  Upon receiving the speed information t = t1, the speed controller 160 supplies a pulse train having a corresponding period T1 to the fixing drive motor 190A (step S5), and rotationally drives the fixing drive motor 190A.

  Thereafter, a printing process is performed (step S6). That is, when the image formation control unit 100 issues a print instruction to the image formation unit 140 and the transfer control unit 150, a toner image based on the image data is formed on each photosensitive drum by the image formation unit 140, and at the same time, the toner is transferred by the transfer unit 180. The image is transferred to the recording paper. The toner-formed recording sheet on which the toner image has been transferred is conveyed to the fixing unit 190 by the conveyance belt 9 at a conveyance speed of t2.

  When the toner forming recording paper is taken in, the fixing unit 190 heats and fixes the toner image on the recording paper with both rollers, and conveys the recording paper and discharges it to a discharge unit (not shown).

  If the next image data is received after the printing process is completed, the above printing process is repeated again. If it has not been received, the printing process is terminated, and it waits until print instruction information and print data are transmitted from the host device again.

  By the way, according to the first embodiment, when printing is performed on the recording paper A4 having a width smaller than the reference recording paper A3, the transport speed t1 (T1) for transporting the recording paper in the fixing unit is the transport belt. Therefore, the recording sheet can be conveyed at the conveying speed t2 of the conveying belt without being bent between the fixing unit and the transfer unit. That is, even when a recording sheet having a small width is conveyed at the center of the fixing unit, the recording sheet conveying speed in the fixing unit and the conveying speed of the recording sheet by the conveying belt can be made substantially the same, and the recording sheet is curved. It does not. Further, as is apparent from the speed calculation formula, in the case of the recording paper A3 Nobi having a large width dimension, the transport speed for transporting the recording paper in the fixing unit is t0, which is lower than the transport speed t2 of the transport belt. Therefore, the recording paper can be conveyed without applying tension. That is, even when recording paper having a large width is conveyed by the entire fixing unit (including the end side), the conveyance speed of the recording paper in the fixing unit and the conveyance speed of the recording paper by the conveyance belt can be made substantially the same. No tension is applied to the recording paper.

  FIG. 9 is a block diagram of the image forming apparatus according to the second embodiment.

  In the second embodiment, the storage unit 170 holds a set width dimension information / set speed information correspondence table 170B in which speed information is associated with preset width dimension information.

  FIG. 11 is a diagram showing the set width dimension information / set speed information correspondence table 170B. The speed information t0 to tN corresponding to the width dimension information is obtained by experiments at the design stage.

  Further, the speed information determination unit 102 of the image formation control unit 100 according to the second embodiment refers to the set width dimension information / set speed information correspondence table 170B based on the width dimension information acquired from the width dimension information acquisition unit 101. Thus, the speed information t of the fixing unit 190 is determined. Other configurations are the same as those of the first embodiment.

  FIG. 10 is an operation flowchart of the image forming apparatus according to the second embodiment.

  By the way, in this embodiment, the conveyance speed of the conveyance belt 9 is set to coincide with the conveyance speed t2 of the recording sheet “A3” of the fixing unit 190.

  In the second embodiment, the “A4” recording paper is detected using the detection sensors S1, S2, and S3 of the recording paper information detection sensor 120, and the recording paper information in the storage unit 170 is detected based on the detected “A4” recording paper. By referring to the width dimension information correspondence table 170A, the width dimension information W1 of the recording paper is specified, and the set width dimension information / set speed information correspondence table 170B is referred to based on the specified width dimension information W1. Thus, the speed information t1 of the fixing unit 190 is determined, the obtained speed information t1 is supplied to the fixing driving motor 190A of the fixing unit 190, and the fixing driving motor 190A is driven to rotate so that the width of the recording paper is obtained. The recording paper conveyance speed of the fixing unit 190 is controlled accordingly.

  First, when a power switch of an image forming apparatus (not shown) is turned on, the image forming control unit 100 performs a predetermined initialization process based on a control program. At this time, the reference width dimension information W2 and speed information t2 are set in the memory of the speed information determination means 102. When the initialization process ends, the image forming apparatus waits until print instruction information and print data are transmitted from the host apparatus.

  When the print instruction information and the print data are received from the upper apparatus, the image formation control unit 100 analyzes the print instruction information and acquires the analysis instruction information. Then, the print data is expanded based on the obtained analysis instruction information to generate image data (step S1).

  Then, the image formation control unit 100 sends the reference degree information t2 to the speed control unit 160, and the speed control unit 160 supplies the period T2 pulse train to the fixing drive motor 190A based on the reference speed information t2, and rotationally drives it. (Step S2).

  Further, when the image formation control unit 100 instructs the paper feeding unit 1 (see FIG. 3) to feed the recording paper and transports the recording paper, the width dimension information acquisition unit 101 performs the recording paper information detection sensor 120. Detection information indicated by ON and OFF from each of the detection sensors S1, S2, and S3 is fetched, and based on the fetched detection information, the recording paper information / detection information correspondence table 170C of the storage unit 170 is referred to correspond to the detection information. Specify recording paper information.

  In the second embodiment, the detection information of each of the detection sensors S1, S2, and S3 is turned on, off, and off, respectively. Therefore, the width dimension information acquisition unit 101 uses the recording paper information / detection information table based on the detection information. By referring to 170C, “A4” recording paper information is specified.

  Subsequently, the width dimension information acquisition unit 101 refers to the recording sheet information / width dimension information table 170A based on the specified “A4” recording sheet information, and acquires the width dimension information W1 corresponding to the recording sheet information ( In step S3), the width dimension information W1 is transmitted to the speed information determining means 102.

  The speed information determination means 102 should be supplied to the speed control means 160 by referring to the set width dimension information / set speed information correspondence table 170B based on the width dimension information W1 acquired by the width dimension information acquisition means 101. Speed information t1 is determined (step S4).

  The speed information determination unit 102 transfers the determined speed information t = t1 to the speed control unit 160.

  Upon receiving the speed information t = t1, the speed control unit 160 supplies a pulse train having a corresponding period T1 to the fixing drive motor 190A (step S5), and rotates the fixing drive motor 190A.

  Thereafter, a printing process is performed (step S6). That is, when the image formation control unit 100 issues a print instruction to the image formation unit 140 and the transfer control unit 150, a toner image based on the image data is formed on each photosensitive drum by the image formation unit 140, and at the same time, the toner is transferred by the transfer unit 180. The image is transferred to the recording paper. Then, the toner-formed recording sheet on which the toner image is transferred is conveyed toward the fixing unit 190 by the conveyance belt 9 at a conveyance speed of t2.

  When the toner forming recording paper is taken in, the fixing unit 190 heats and fixes the toner image of the recording paper with both rollers, conveys the recording paper, and discharges the recording paper to a discharge unit (not shown).

  If the next image data is received after the printing process is completed, the above printing process is repeated again. If it has not been received, the printing process is terminated, and it waits until print instruction information and print data are transmitted from the host device again.

  According to the second embodiment, as described above, when printing is performed on the recording paper A4 having a width smaller than the reference recording paper A3, the conveyance speed t1 (T1) for conveying the recording paper at the fixing unit. However, since the recording speed is higher than the conveyance speed t2 for conveying the recording paper on the conveyance belt, the recording paper can be conveyed at the conveyance speed t2 of the conveyance belt without being bent between the fixing section and the transfer section. That is, even when a recording sheet having a small width is conveyed at the center of the fixing unit, the recording sheet conveying speed in the fixing unit and the conveying speed of the recording sheet by the conveying belt can be made substantially the same, and the recording sheet is curved. It does not. Further, in the case of the recording paper A3 Nobi having a large width dimension, the transport speed for transporting the recording paper in the fixing unit is t0, which is smaller than the transport speed t2 of the transport belt, so that tension is applied to the recording paper. Can be transported without any problem. That is, even when recording paper having a large width is conveyed by the entire fixing unit (including the end side), the conveyance speed of the recording paper in the fixing unit and the conveyance speed of the recording paper by the conveyance belt can be made substantially the same. No tension is applied to the recording paper.

  FIG. 12 is a block diagram of the image forming apparatus according to the third embodiment.

  The image formation control unit 100 according to the third exemplary embodiment includes an image density information acquisition unit 104. The image density information acquisition unit 104 includes a memory 104A, and the memory 104A holds reference image dot number information d and reference density information m set in advance as a reference.

  When receiving print data from the host device, the image density information acquisition unit 104 expands the print data, counts the number of dots in the expanded image data for one page, and acquires image dot number information. Then, based on the reference image dot number information d, the reference density information m, and the image dot number information, as described later, the image density information D indicating the ratio of the number of dots included in one page of the recording paper of the received image data. Is calculated.

  The storage unit 170 holds a set image density information / set speed information correspondence table 170D in which speed information is associated with preset image density information.

  FIG. 14 shows a set image density information / set speed information correspondence table 170D. The speed information v0 to v8 corresponding to the image density information is obtained by an experiment in the design stage, and the corresponding speed information gradually decreases in speed as the acquired image density information increases. Is set.

  The image formation control unit 100 includes a speed information determination unit 102. The speed information determination means 102 has a memory 102B and holds reference speed information v set in advance as a reference. Further, the speed information determination unit 102 refers to the set image density information / set speed information correspondence table 170D based on the image density information D acquired from the image density information acquisition unit 104, thereby obtaining the speed information of the fixing unit 190. It is characterized by deciding.

  When the speed control unit 160 receives the speed information from the speed information determination unit 102, the speed control unit 160 controls the rotation of the fixing drive motor 190A based on the speed information.

  FIG. 13 is an operation flowchart of the image forming apparatus according to the third embodiment.

  In the third embodiment, the recording paper to be transported is long paper, and the transport speed of the transport belt 9 is set to be slightly slower than the reference speed information v of the fixing unit 190. The reference image dot number information d is 50,000 dots, the reference density information m is 30%, and the acquired image dot number information d0 is 60,000 dots.

  First, when a power switch of an image forming apparatus (not shown) is turned on, the image forming control unit 100 performs a predetermined initialization process based on a control program. At this time, the reference speed information v is set in the memory 102B of the speed information determining means 102. The memory 104A of the image density information acquisition unit 104 stores reference image dot number information d (= 50,000 dots), reference density information m (= 30%), and an image density information calculation formula D = d0 / d × m. Is set. When the initialization process ends, the image forming apparatus waits until print instruction information and print data are transmitted from the host apparatus.

  When the print instruction information and the print data are received from the upper apparatus, the image formation control unit 100 analyzes the print instruction information and acquires the analysis instruction information. Then, the print data is expanded based on the acquired analysis instruction information to generate image data (step S1).

  Further, the image forming control unit 100 transfers the reference speed information v to the speed control unit 160, and the speed control unit 160 supplies a pulse train having a cycle V to the fixing drive motor 190A and rotates based on the reference speed information v. Drive. (Step S2).

  Then, the image density information acquisition unit 104 counts the number of dots included in one page of recording paper of the image data from the received image data, acquires the image dot number information d0 (= 60,000 dots), and obtains the reference image. Based on the dot number information d (= 50,000 dots), the reference density information m (= 30%), and the image dot number information d0 (= 60,000 dots), the image density information calculation formula is used to calculate one page of recording paper. The image density information D (= 36%) indicating the ratio of the number of dots of the image data included in is calculated (step S3).

  Subsequently, the image formation control unit 100 instructs the paper feeding unit 1 (see FIG. 3) to feed the recording paper, and transports the recording paper. (Step S4)

The speed information determination unit 102 refers to the set image density information / set speed information correspondence table 170D on the basis of the acquired image density information D (= 36%), thereby speed information v0 to be supplied to the speed control unit 160. Decide
The speed information v0 is transferred to the speed control means 160. (Step S5). Note that V0 is always selected when the image density information D is in the range of 36 ≦ D <39.

  Upon receiving the speed information v0, the speed control unit 160 supplies a pulse train having a corresponding cycle V0 to the fixing drive motor 190A, and rotationally drives the fixing drive motor 190A (step S6).

  Thereafter, a printing process is performed (step S7). That is, when the image formation control unit 100 instructs the image formation unit 140 and the transfer control unit 150 to print, a toner image based on the image data is formed on each photosensitive drum by the image formation unit 140 and also formed by the transfer unit 180. The toner image thus transferred is transferred to the recording paper. The toner-formed recording sheet is conveyed to the fixing unit 190 by the conveyance belt 9 at a conveyance speed v.

  When the toner forming recording paper is taken in, the fixing unit 190 heats and fixes the toner image on the recording paper with both rollers, and conveys the recording paper and discharges it to a discharge unit (not shown).

  If the next image data is received after the printing process is completed, the above printing process is repeated again. If it has not been received, the printing process is terminated, and it waits until print instruction information and print data are transmitted from the host device again.

  By the way, as the number of image dots for one page increases, the recording paper adheres to the peripheral surface of the fixing roller through the toner with a large force, and there is a possibility that a large tension is applied to the recording paper. On the other hand, according to the third embodiment, for example, in the printing process of a long recording paper, when the number of image dots (= 60,000 dots) acquired is larger than the reference image dot number d (= 50,000 dots), Since the recording sheet conveyance speed of the fixing unit is lower than v0 (V0), the recording sheet can be conveyed without applying tension to the long recording sheet on which the toner image is formed.

  In the first and second embodiments, the detection of the recording paper has been described using the detection sensors S1, S2, and S3 of the recording paper information detection sensor 120. However, the line sensor is used for detection of the recording paper. Alternatively, the recording paper width dimension information W may be directly detected, and the speed information T corresponding to the detected width dimension information W may be set in the speed information determination unit 102.

  In the first and second embodiments, the recording paper width dimension information may be set via the host device and the input terminal of the operation unit 110.

  Further, in the above embodiment, in order to fix the toner image formed on the recording paper, the fixing portion as a fixing member is constituted by the fixing roller and the pressure roller, and the toner image on the recording paper is fixed by heating. However, for example, it may be configured by a pressure belt in which a belt is wound around a pressure roller formed in a drum shape whose outer diameter of the central portion is larger than both end portions. In addition, the belt is wound around a pressure roller formed in a cylindrical shape, and the central part of the belt is formed larger than both ends, thereby forming a pressure belt that makes the nip pressure uniform when fixing a toner image. May be. Furthermore, the fixing unit may be constituted by a fixing film and a pressure film.

1 is a block configuration diagram of an image forming apparatus of Embodiment 1. FIG. The figure which shows the roller shape of a fixing | fixed part. 1 is a schematic configuration diagram of an image forming apparatus. The figure which shows the corresponding | compatible table of recording paper information and the width dimension information of a recording paper. The positional relationship diagram of a recording paper information detection sensor and recording paper. The figure which shows the correspondence table of the detection information of a recording paper and a recording paper information detection sensor. The figure which shows the pulse period of a fixing drive motor. 2 is an operation flowchart of the first embodiment. FIG. 3 is a block configuration diagram of an image forming apparatus according to a second embodiment. 9 is an operation flowchart of the second embodiment. The figure which shows the setting width dimension information and setting speed information correspondence table. FIG. 6 is a block configuration diagram of an image forming apparatus according to a third embodiment. 9 is an operation flowchart of the third embodiment. The figure which shows the setting image density information and setting speed information correspondence table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper feed part 3 Photosensitive drum 4 Photosensitive drum 5 Photosensitive drum 6 Photosensitive drum 8 Transfer roller 9 Conveyor belt 11 Fixing roller 12 Pressure roller 100 Image formation control part 101 Width information acquisition means 102 Speed information determination means 102A Memory 102B Memory 104 Image density information acquisition means 104A Memory 110 Operation section 120 Recording paper information detection sensor 140 Image forming section 150 Transfer control section 160 Speed control means 170 Storage section 170A Recording paper information / width dimension information correspondence table 170B Set width dimension information / set speed information Correspondence Table 170C Recording Paper Information / Detection Information Correspondence Table 170D Set Image Density Information / Set Speed Information Correspondence Table 180 Transfer Section 190 Fixing Section 190A Fixing Drive Motor

Claims (6)

  1. A transfer unit that transfers a toner image to a recording paper of an arbitrary size that is conveyed, a fixing member that heat-fixes the toner image on the recording paper that is conveyed from the transfer unit, and a drive that rotationally drives the fixing member A fixing portion having a portion,
    Width dimension information acquisition means for acquiring width dimension information indicating the width dimension of the recording paper;
    Speed information determining means for determining transport speed information of the recording paper corresponding to the width dimension information acquired by the width dimension information acquiring means;
    Speed control means for controlling the drive unit based on the transport speed information;
    An image forming apparatus comprising:
  2.   2. The image according to claim 1, wherein the fixing member includes a fixing roller and a pressure roller, and is formed in a drum shape in which an outer diameter of a central portion of the pressure roller is larger than both end portions thereof. Forming equipment.
  3.   3. The image forming apparatus according to claim 1, wherein the fixing member is configured by a belt wound around the pressure roller.
  4. The speed information determining means is based on the following formula:
    t = t0 × (1 + γ (W−W0)) | (where t: transport speed information, t0: reference transport speed information set as a reference in advance, γ (> 0): width coefficient, W: acquired width dimension) 2. The image forming apparatus according to claim 1, wherein conveyance speed information for conveying the recording paper of the drive unit is determined.
  5.   The speed information determination unit includes a speed information correspondence table in which conveyance speed information is associated with each preset width dimension information, and the speed information correspondence table is determined based on the acquired width dimension information of the recording paper. The image forming apparatus according to claim 1, wherein conveyance speed information for conveying the recording sheet of the driving unit is determined by referring to the image forming apparatus.
  6. A transfer unit that transfers a toner image to a recording paper of an arbitrary size that is conveyed, a fixing member that heat-fixes the toner image on the recording paper that is conveyed from the transfer unit, and a drive that rotationally drives the fixing member In an image forming apparatus comprising a fixing unit having a unit
    A speed information correspondence table in which the conveyance speed information of the recording paper is associated with each image density information indicating the ratio of the number of dots of the image;
    Counts the number of image dots contained in one page of recording paper in the image data, and calculates the image density information of the image data based on the number of image dots and the reference image dot number and reference image density set in advance as a reference Image density information acquisition means for
    Based on the acquired image density information, by referring to the speed information correspondence table, based on the speed information determining means for determining the transport speed information of the recording paper of the drive unit and the determined transport speed information, An image forming apparatus comprising: a speed control unit that controls the driving unit.
JP2004161934A 2004-05-31 2004-05-31 Image forming apparatus Pending JP2005345531A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011150116A (en) * 2010-01-21 2011-08-04 Konica Minolta Business Technologies Inc Image forming apparatus
US8087670B2 (en) * 2008-02-26 2012-01-03 Ricoh Company, Limited Sheet conveying device and image forming apparatus
US8121502B2 (en) 2008-04-03 2012-02-21 Ricoh Company, Ltd. Fixing unit including heating regulator to adjust a heating width of a heating member

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8087670B2 (en) * 2008-02-26 2012-01-03 Ricoh Company, Limited Sheet conveying device and image forming apparatus
US8121502B2 (en) 2008-04-03 2012-02-21 Ricoh Company, Ltd. Fixing unit including heating regulator to adjust a heating width of a heating member
JP2011150116A (en) * 2010-01-21 2011-08-04 Konica Minolta Business Technologies Inc Image forming apparatus

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