JP2007121706A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of accurately transferring a toner image carried on an image carrier to a predetermined position on recording paper at a transfer position by easy control by restraining the influence of heat in consecutive printing. <P>SOLUTION: The image forming apparatus is equipped with: an image carrier; a transfer means for transferring the toner image carried on the image carrier to sheet type recording paper at the transfer position; a resist roller for conveying the recording paper toward the transfer position; a number-of-transfer-times integrating means for integrating the number of transfer times of toner images transferred to the recording paper at the transfer position from starting a job; a storage means for storing the integrated number of transfer times and the set content of the job; and a control means for controlling the driving of the resist roller so that conveying time required from a start position of the conveyance of the recording paper by the resist roller to the transfer position may be matched with the predetermined set time based on the recorded number of transfer times and the set content in the consecutive printing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a multifunction machine having these functions, and prevents the influence of heat at the time of continuous printing, and a toner image carried on an image carrier is recorded on a recording paper. The present invention relates to an image forming apparatus capable of transferring to a predetermined position.

  2. Description of the Related Art Conventionally, in an image forming apparatus, a registration roller is driven and controlled, a recording sheet is conveyed to a predetermined transfer position in a transfer unit, and is carried on an image carrier such as a photosensitive drum or an intermediate transfer member. A technique for bringing a recording sheet to a transfer position at a predetermined timing with respect to a toner image is known.

Further, in the image forming apparatus, in order to prevent the toner image from being transferred to a predetermined position on the recording paper due to a change in the diameter of the conveyance roller due to heat in the apparatus or the like, the temperature of the conveyance roller is prevented by a temperature detection unit. A technique is known in which the toner image carried on the image carrier can be transferred to a predetermined position on the recording paper by performing conveyance control of the conveyance roller based on the detection result (patent) References 1 and 2).
JP 2000-44083 A JP-A-9-281187

  As a problem of the background art, in the former image forming apparatus, when continuous printing is performed, the heat generated in the image forming apparatus is carried on the image carrier due to a change in the diameter of the registration roller. There is a problem in that the toner image cannot be transferred to a predetermined position on the recording paper and the image is displaced.

  In order to prevent this image misalignment, if control of the registration roller is attempted by a method using a temperature detecting means such as the latter image forming apparatus, the control becomes complicated and difficult to control easily. was there.

  The present invention has been made in view of the above problems, and an object of the present invention is to prevent the influence of heat during continuous printing and transfer a toner image carried on an image carrier by simple control. An object of the present invention is to provide an image forming apparatus capable of accurately transferring to a predetermined position of a recording sheet at a position.

  The object of the present invention can be achieved by the following means. That is, an image carrier, transfer means for transferring a toner image carried on the image carrier to a sheet-like recording paper at a transfer position, a registration roller for conveying the recording paper toward the transfer position, Transfer number integration means for integrating the number of transfer of the toner image transferred to the recording paper at the transfer position from the start of the job, storage means for storing the integrated number of transfer times and job settings, and recording during continuous printing Based on the number of times of transfer and the set content, the registration roller is driven so that the conveyance time from the recording paper conveyance start position by the registration roller to the transfer position is matched with a predetermined setting time. An image forming apparatus comprising a control means for controlling.

  According to the image forming apparatus of the present invention, the conveyance time from the recording paper conveyance start position by the registration roller to the transfer position is matched with a predetermined set time based on the recorded number of times of transfer and the set content. In addition, since the driving of the registration roller is controlled, the influence of heat during continuous printing is prevented, and the toner image carried on the image carrier is accurately controlled at a predetermined position on the recording paper by the simple control. Can be transferred well.

  In addition, the image carrier on which the toner images carried on a plurality of photosensitive drums are transferred is conveyed by a conveyor belt, and the toner image carried on the image carrier is transferred to a recording sheet at a transfer position to form a color image. When the image forming apparatus to be formed and the double-sided printing mode for creating an image on both sides of the recording paper are selected, the toner image carried on the image carrier is transferred to the recording paper conveyed by the rotational drive of the registration roller. In the image forming apparatus for transferring the recording paper, the recording paper is reversed by the reversing and conveying means, guided again to the registration roller, and the new toner image carried on the image carrier is transferred to the other surface of the recording paper. It comes to have an effect.

  The image forming apparatuses according to Embodiments 1 to 3 according to the present invention will be described with reference to the drawings.

  First, a schematic configuration of a part of the image forming apparatus common to the first to third embodiments will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to an embodiment, and FIG. 2 is a view for explaining a recording paper transport mechanism of FIG.

  The image forming apparatus includes an image forming apparatus main body GH and an image reading unit YS, which will be described separately.

  The image forming apparatus main body GH includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a paper feeding and conveying unit, a fixing unit 24, and the like.

  The image forming unit 10Y that forms a yellow image includes an image carrier 1Y made of a drum-type photosensitive member, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a charging unit 2Y disposed around the image carrier. It has cleaning means 8Y composed of a blade.

  The image forming unit 10M that forms a magenta image includes an image carrier 1M made of a drum-type photoconductor, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 8M made of a blade.

  The image forming unit 10C for forming a cyan image includes an image carrier 1C made of a drum-type photoconductor, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 8C made of a blade.

  Further, the image forming unit 10K for forming a black image has an image carrier 1K made of a drum-type photoconductor, a charging means 2K, an exposure means 3K, a developing means 4K, and a cleaning means 8K made of a blade.

  The above-mentioned image carrier for each color, charging means, exposure means, and developing means constitute an image forming means. Each of the exposure means described above includes a laser light source, an fθ lens, a collimator lens, a polygon mirror, and the like. Each of the developing means described above includes, for example, a developer carrier S composed of a sleeve capable of carrying a two-component developer mainly composed of toner and a carrier on its surface and transporting it to the development area, and the developer carrying member. A magnet provided in a fixed position inside the body S is provided. The intermediate transfer body 6 is rotatably supported by a plurality of rollers.

  In the present embodiment, the toner image formed on the photosensitive member as the image carrier is then transferred onto the intermediate transfer member 6 and then transferred onto the final recording paper. Although the intermediate transfer member can also be said to be an image carrier, the photosensitive member is hereinafter referred to as a photosensitive member, and the intermediate transfer member is referred to as an intermediate transfer member. However, in the present embodiment, the image transfer member according to the present invention is an image transfer member because of the balance with the recording paper.

  First transfer means 7Y, 7M, 7C, and 7K made of conductive rollers are arranged inside the intermediate transfer member 6 and at positions facing the above-described respective photosensitive members. The first transfer unit is biased by a spring so as to press the intermediate transfer member 6 against the photosensitive member.

  In addition, a backup roller 7B provided in the intermediate transfer member 6 and a transfer roller 7A that is pressed against the belt are prepared as transfer means (also referred to as second transfer means) at the transfer position with respect to the recording paper. Hereinafter, for convenience of explanation, the transfer roller 7A is referred to as transfer means.

  Reference numeral 8A denotes a cleaning means comprising a blade for keeping the surface of the intermediate transfer member 6 clean. The fixing unit 24 is composed of a roller-type fixing device having a first heating roller and a second heating roller or a second roller provided so as to be able to rotate in contact with the first heating roller.

  Next, the image reading unit YS will be described. An image reading unit YS is provided above the image forming apparatus main body GH. The image reading unit YS includes an automatic document feeding unit 210 and a document image scanning exposure unit 220.

  The document d is placed on a document placing table 211 provided in the automatic document feeding unit 210, separated one by one by a separating unit, and conveyed to a reading position by a conveying unit including a roller, a rotatable drum 212, and the like. The document image scanning exposure device means 220 reads the image.

  The document image scanning exposure unit 220 includes a first block 221 integrally including an irradiation lamp and a first mirror, a second block 223 integrally including a second mirror and a third mirror, and an imaging unit. It has a lens 225 and a line image sensor CCD.

  In other words, the image of the document d in the transported state is irradiated by the irradiation lamp at the reading position, reaches the imaging lens 225 via the three mirrors described above, and the line is sequentially formed by the action of the imaging lens 225. The image is formed on the image sensor CCD and read.

  The image information (analog signal) read by the line image sensor CCD is appropriately converted into analog processing, A / D conversion, shading correction, image compression processing, etc. in an image processing unit provided in the control means (described later). After the processing, it is stored in the RAM 73 (see FIG. 3) in the control means 70.

  The stored image data is read according to the image forming process and sent to the exposure means (3Y, 3M, 3C, 3K).

  The exposure unit irradiates the surface of the photoconductor (1Y, 1M, 1C, 1K) with laser light modulated according to the image data, and creates an electrostatic latent image corresponding to the image data on the photoconductor.

  The automatic document feeder 210 includes an automatic double-sided document feeder, and reads the contents of a large number of documents d fed from the document table 211 all at once, and RAM 73 (see FIG. 3). It is possible to accumulate in

  Returning to the description of the image forming apparatus main body GH, at the lower part of the image forming apparatus main body GH, there are paper feed cassettes 20 for storing sheet-like recording paper P, which are provided in three stages in the vertical direction. Reference numeral 21 denotes a paper feeding unit, and 22A denotes a conveyance roller provided at a downstream position of the paper feeding unit 21. These are provided corresponding to the respective paper feed cassettes, but in FIG. 1, reference numerals are attached only to the uppermost paper feed cassette as a representative. 22B, 22C, and 22D are transport rollers provided in the common transport path portion of the first transport path 101, and transport the recording paper P fed from each paper feed cassette toward the registration rollers 23.

  The transfer number integrating means 80 (see FIG. 2) is installed between the conveying roller 22D and the registration roller 23, and counts when the recording paper P passes. Since the recording paper that has passed through the transfer number integrating means 80 is then transferred by the transfer means 7A, the transfer number integrating means 80 integrates the recording sheet transfer number n.

  The registration roller 23 is rotationally driven and controlled so that the recording paper P can always reach the transfer position with good timing with respect to the toner image formed on the intermediate transfer body 6. The driving source of the registration roller 23 is a stepping motor (not shown) and is provided as a dedicated unit for driving only the registration roller, but is not particularly limited. When the recording paper P fed and conveyed via the conveying roller 22B or the like according to the image forming process comes into contact, the rotation is controlled to be stopped.

  The conveyance path 102 from the registration roller 23 to the discharge roller 25 is a second conveyance path (referred to as the second conveyance path 102), passes through the right side of the conveyance path switching means 50, and communicates with the conveyance roller 53. Is a third conveyance path (referred to as the third conveyance path 103), reverses the recording paper P sent to the third conveyance path 103, and conveys it via conveyance rollers 54, 55, 56, and a drum 58. The conveyance path 104 reaching the roller 22D is a fourth conveyance path (referred to as a fourth conveyance path 104), and reverses the recording paper P sent to the third conveyance path 103, and passes through the left side of the conveyance path switching means 50. A conveyance path 105 (referred to as a fifth conveyance path 105) reaching the discharge roller 25 is shown.

  Next, the overall operation related to the image forming process of the image forming apparatus will be briefly described separately for single-sided printing and double-sided printing. For convenience, when there is no need to divide a plurality of means such as an exposure means or a photoconductor by color, they are simply referred to as an exposure means 3 and a photoconductor 1.

  First, the single-sided printing mode will be described with reference to FIG. As described above, when the original is read by the line image sensor CCD and the exposure according to the image data generated by the image processing unit is performed by the exposure unit 3, the photosensitive member 1 is uniformly charged. An electrostatic latent image is created.

  The exposure is performed for each color at an appropriate timing, and the created latent image is converted into a toner image for each color by the developing means 4. These toner images are sequentially transferred to the intermediate transfer member 6 by the action of the first transfer means 7 and are superimposed on the intermediate transfer member 6 to form a full-color toner image. The toner image is moved toward the transfer position by the continuous rotation of the intermediate transfer body 6. On the other hand, the surface of the photoreceptor 1 that has passed through the transfer region is cleaned by the cleaning means 8 and is prepared for the next image creation.

  At this time, the recording paper P to be fed in accordance with the image forming process is already in contact with and sandwiched by the registration roller 23, and the transfer position (transfer means) is transferred in accordance with the rotation of the registration roller 23 that is driven in a timely manner. 7A), the toner image area and the recording paper P are superimposed with high accuracy.

  At the transfer position, the toner image on the intermediate transfer body 6 is transferred onto the recording paper P under the action of a transfer means (second transfer means) 7A to which an appropriate current value is applied. After fixing the toner image by the heating and pressing action of the fixing means 24 provided on the second conveying path 102, the toner image is discharged to the tray 26 provided outside the apparatus via the discharge roller 25.

  At this time, the transport path switching means 50 is held at the position indicated by the solid line in the drawing, and the second transport path 102 is released. The intermediate transfer body 6 after the image is transferred onto the recording paper P by the transfer means 7A is cleaned by the cleaning means 8A and prepared so as to function as a new intermediate transfer body.

  Next, the duplex printing mode will be described. The recording sheet P on which an image is formed on one side is guided to the third transport path 103 by the transport path switching of the transport path switching means 50 after the fixing process is performed, and the rear end is sandwiched between the transport rollers 53 Stopped at. Next, the sheet is sent upward by the rotation of the conveyance roller 53 that is rotationally driven in the opposite direction to the above, and is sent to the fourth conveyance path 104 that is released by the conveyance path switching of the conveyance path switching member (not indicated), so that the front and back are reversed. Is done. Further, the recording paper P is continuously conveyed by the conveyance roller groups 55 and 56 and the drum 58, and is brought into contact with the registration rollers that are already in the rotational drive stopped state. Next, the recording paper P is fed toward the transfer position by the registration roller 23 that is rotationally driven and controlled at the timing of superimposing on the toner image carried on the intermediate transfer body 6, and receives the action of the transfer means 7 A, The toner image is carried on the second surface of the toner. Then, after the fixing process is performed, the sheet is discharged out of the apparatus via the discharge roller 25. At this time, the transport path switching unit 50 releases the second transport path 102.

<Embodiment 1>
The image forming apparatus of Embodiment 1 will be described with reference to the drawings. The mechanical structure related to the image forming apparatus according to the first embodiment is the same as that shown in FIGS.

  A control system related to the image forming apparatus according to the first embodiment will be described. FIG. 3 is a block diagram of a control system according to the first embodiment.

  In FIG. 3, the control system includes a control unit 70, a transfer number integrating unit 80, a transfer unit 7 </ b> A, an operation display unit 60, an image reading unit YS, an exposure unit 3, an image forming unit 10, and a registration roller 23. The control means 70 includes a CPU 71, ROM 72, RAM 73, and memory unit 74. The control unit 70 performs substantially all control such as sequence control for image formation, conveyance control of the recording paper P, and heating control of the fixing unit 24.

  The ROM 72 stores a control program for the image forming apparatus, and the RAM 73 stores the number of times of transfer n, the recording paper size that is the setting content of the job, and the classification of one side and both sides. The memory unit 74 stores a table TL1 for obtaining paper feed parameters. The transfer number integrating means 80 integrates the transfer number n.

  The above-described control means 70 obtains a paper feed parameter from the table TL1 in the memory unit 74 based on the number of times of transfer n stored in the RAM 73 and the set contents of the job during continuous printing. Then, the rotation speed per unit time of the registration roller 23 is controlled so that the conveyance time from the conveyance start position of the recording paper P by the registration roller 23 to the transfer position is matched with a predetermined set time.

  Here, the table TL1 will be described in detail. FIG. 4 is a table for obtaining feeding parameters according to the first embodiment. As shown in FIG. 4, the table TL1 is a table in which the number of times of transfer n and job settings are associated with a reduction rate of the number of rotations per unit time of the registration roller, which is a paper feed parameter. Note that the job settings include double-sided or single-sided as an example of the mode, and A3 or A4 as an example of the recording paper size. The recording paper size is not limited to A3 and A4. For example, when the length of the recording paper in the feeding direction is 210 mm or more, it may be classified as a large size, and when it is 210 mm or less, it may be classified as a small size. .

  Further, the table TL1 will be described in detail as an example. When the duplex mode is selected as the mode and A3 is selected as the recording paper size, the number of times of transfer n from the start of the job is 1 to 100, and the unit time per unit time of the registration roller. This indicates that the speed reduction rate is 0%, and the speed reduction rate is 0.1% until the number of times of transfer n is 100 to 200.

  This table TL1 can be obtained by an experiment using the image forming apparatus shown in FIG. By this correction, even if the diameter of the registration roller changes due to heat, the conveyance time from the recording paper conveyance start position to the transfer position by the registration roller can be matched with a predetermined set time. .

  In the table TL1, the influence of heat increases as the number of times of transfer n increases, so the deceleration rate also increases. In the double-sided printing mode, the recording paper is transferred and heat-fixed on the surface of the recording paper, and then the heated recording paper is conveyed again by the registration roller 23, so that heat is transferred to the registration roller and the registration roller expands. It is easy to reduce the deceleration rate compared to the single-sided printing mode.

  Next, a control example of the image forming apparatus according to the first embodiment will be described. FIG. 5 is a flowchart for explaining a control example according to the first embodiment.

  As an example, an example in which two originals, double-sided printing mode, recording paper size A3, number of transfers n = 200 (corresponding to 100 recording papers) is selected, and paper feed parameters are obtained using table TL1, and continuous printing will be described. I will do it.

  In FIG. 5, in S11, the double-sided printing mode, the recording paper size A3, and the number of transfers n = 200 are input from the operation display unit 60 (FIG. 1).

  In S12, after two originals are read, the recording paper P is conveyed from the paper feed cassette 20 (FIG. 1), and the recording paper P is transferred by the transfer number integrating means 80 (FIG. 2) provided near the registration roller 23. The number of times of transfer n is integrated when passing.

  In S13, it is determined whether or not the accumulated transfer number n exceeds a preset transfer number n = 200. If not, the process proceeds to S14, and if it exceeds, the job ends.

  In S14, it is determined whether or not the transfer number n shown in the table TL1 (FIG. 4) exceeds 100, which is the transfer frequency dividing area. If not, the process proceeds to S15, and the recording paper P is loaded by the rotation of the registration roller 23. In step S18, the toner image on the image carrier is transferred to the recording paper P at the transfer position, fixed, and the process returns to step S12. During this time, the recording paper P is reversely conveyed and printed.

  If the number of times of transfer n exceeds 100 in the determination of S14, the process proceeds to S16, and a reduction rate (feeding parameter) of the number of rotations of the registration roller 23 per unit time is obtained using the table TL1 (FIG. 4). In S17, the rotational speed of the registration roller per unit time is reduced by 0.1%. Thereafter, the recording paper is conveyed in S15 described above, transferred and fixed in S18, and the process returns to S12.

  As described above, according to the first embodiment, during continuous printing, the influence of heat is prevented by simple control, and the toner image carried on the image carrier is transferred to the predetermined position of the recording paper at the transfer position. It becomes controllable so that it can be transferred to a position. If the table TL1 is used, the paper feed parameter can be easily obtained.

<Embodiment 2>
Next, an image forming apparatus according to a second embodiment will be described with reference to the drawings. The image forming apparatus according to the second embodiment is functionally the same except that the registration roller drive control method according to the first embodiment is different. Therefore, the description will focus on the differences from the first embodiment.

  With respect to the control system related to the image forming apparatus of the second embodiment, different parts will be described with reference to the block diagram of the control system of the first embodiment shown in FIG.

  In FIG. 3, the ROM 72 stores a control program related to the image forming apparatus of the second embodiment, and the memory unit 74 stores a table TL2 for the second embodiment for obtaining paper feed parameters. .

  In the control unit 70 according to the second embodiment, during continuous printing, a sheet feeding parameter is obtained from the table TL2 in the memory unit 74 based on the number of times of transfer n stored in the RAM 73 and the setting contents of the job. The conveyance start time of the registration roller 23 is controlled so that the conveyance time from the conveyance start position of the recording paper P by the registration roller 23 to the transfer position is matched with a predetermined set time by the paper parameter.

  Here, the table TL2 will be described in detail. FIG. 6 is a table for obtaining feeding parameters according to the second embodiment. As shown in FIG. 6, the table TL <b> 2 is a table in which the transfer number n and job setting contents are associated with correction of registration roller conveyance start timing, which is a paper feed parameter. The job settings include double-sided or single-sided as the mode, and A3 or A4 as the recording paper size.

  Further, the table TL2 will be described in detail. When the duplex mode is selected as the mode and A3 is selected as the recording paper size, the transfer start time of the registration roller is from 1 to 100 when the transfer number n from the start of the job. It is shown that the correction when the transfer number n is 100 to 200 is 1.3 ms. In other words, since the diameter of the registration roller is expanded by heat and the conveyance speed of the recording paper is increased, this means that the registration roller conveyance start timing is shifted by 1.3 ms. By this correction, even if the diameter of the registration roller changes due to heat, the conveyance time from the recording paper conveyance start position to the transfer position by the registration roller can be matched with a predetermined set time.

  In the embodiment, the conveyance speed of the reference registration roller is 150 mm / sec, the distance between the registration roller 23 and the transfer unit 7A is 200 mm, and the reference arrival time from the registration roller 23 to the transfer position is 1333.3 ms. is there. The table TL2 can be obtained by an experiment using the image forming apparatus shown in FIG.

  In the table TL2, the amount of correction increases because the influence of heat increases as the number of times of transfer n increases. In the double-sided printing mode, transfer to the surface of the recording paper is performed compared to the single-sided printing mode. Since the recording paper heated and fixed and then heated is conveyed again by the registration roller 23, the heat is transmitted to the registration roller, the registration roller expands and becomes larger, and the correction amount also increases.

  Next, a control example of the image forming apparatus according to the second embodiment will be described. FIG. 7 is a flowchart for explaining a control example according to the second embodiment.

  As an example, an example in which two originals, double-sided printing mode, recording paper size A3, number of transfers n = 200 (corresponding to 100 recording papers) is selected, paper feed parameters are obtained using the table TL2, and continuous printing will be described. I will do it.

  In FIG. 7, in S21, the duplex display mode, the recording paper size A3, and the number of times of transfer n = 200 are input from the operation display means 60 (FIG. 1).

  In S22, after the original is read, the recording paper P is conveyed from the paper feed cassette 20 (FIG. 1), and the recording paper P passes by the transfer number integrating means 80 (FIG. 2) provided near the registration roller 23. Then, the transfer number n is counted.

  In S23, it is determined whether or not the transfer number n exceeds the set transfer number n = 200. If not, the process proceeds to S24, and if it exceeds, the job ends here.

  In S24, it is determined whether or not the number of times of transfer n has exceeded 100, which is the transfer area n of the number of times of transfer n shown in Table TL2 (FIG. 6), and if not, the process proceeds to S25. In step S28, the toner image on the image carrier is transferred to the recording paper P at the transfer position, fixed, and the process returns to step S22.

  If it is determined in S24 that the number n of times of transfer exceeds 100, the process proceeds to S26, and a correction amount (feeding parameter) for the registration roller conveyance start timing is obtained from the table TL2 (FIG. 6). In S27, the registration roller conveyance start time is corrected to be delayed by 1.3 ms. Thereafter, in S25, the recording paper P is conveyed by the rotation of the registration roller 23. In S28, the toner image on the image carrier is transferred to the recording paper P at the transfer position, fixed, and the process returns to S22.

  As described above, according to the present invention, during continuous printing, the influence of heat is prevented by simple control, and the toner image carried on the image carrier is placed at a predetermined position on the recording paper at the transfer position. It becomes controllable so that it can transfer. Further, when the table TL2 is used, the feeding parameter can be easily obtained.

<Embodiment 3>
Next, an image forming apparatus according to Embodiment 3 will be described with reference to the drawings. The image forming apparatus according to the third embodiment is functionally the same except that the registration roller drive control method according to the first embodiment is different. Therefore, the description will focus on the differences from the first embodiment.

  With respect to the control system related to the image forming apparatus of the third embodiment, different parts will be described using the block diagram of the control system of the first embodiment shown in FIG.

  In FIG. 3, the ROM 72 stores a control program related to the image forming apparatus of the third embodiment, and the memory unit 74 stores a table (not shown) similar to the table TL2 for obtaining paper feed parameters. It shall be.

  In the control unit 70 according to the third embodiment, during continuous printing, a paper feed parameter is obtained from a table (not shown) in the memory unit 74 based on the number of times of transfer n stored in the RAM 73 and the set contents of the job. The driving of the registration roller 23 is controlled so that the conveyance time from the conveyance start position of the recording paper P by the registration roller 23 to the transfer position is matched with a predetermined set time by the paper feed parameter.

  Here, the table will be described in detail. The table is similar to the above-described table TL2, and will be described with reference to the table TL2. The table used in the third embodiment is the number of times of transfer n, the set contents of the job, and the deceleration time of the registration roller (feeding parameter) ( The table is associated with ΔT2 (see FIG. 8 described later). It is assumed that the job settings include double-sided or single-sided as the mode and A3 or A4 as the recording paper size. This table can be obtained by an experiment using the image forming apparatus shown in FIG.

  Next, a method for decelerating the registration rollers in the third embodiment will be described with reference to FIG. FIG. 8 is a diagram for explaining a registration roller deceleration method according to the third embodiment. The elapsed time is shown on the horizontal axis, and the recording paper conveyance speed of the registration roller is shown on the vertical axis.

  A solid line indicates the locus of the recording paper conveyance speed of the reference registration roller. The registration roller starts to rotate at time T1, then reaches a constant speed, decelerates at time T2, and reaches the transfer position (position of transfer means 7A) at time T3. The time from T1 to T3 is a predetermined time. On the other hand, the dotted line shows the locus of the conveyance speed of the registration roller when the diameter of the registration roller is increased due to heat. The registration roller starts to rotate at time T1, then reaches a transport speed higher than the reference, decelerates by a time ΔT2 before time T2, and reaches a transfer position (position of transfer means 7A) at time T3. The timing of deceleration is adjusted so that the time from T1 to T3 becomes a predetermined time. In the table (not shown), the number of times of transfer n, the setting contents of the job, and the time ΔT2 are associated with each other. By this correction, even if the diameter of the registration roller changes due to heat, the conveyance time from the recording paper conveyance start position to the transfer position by the registration roller can be matched with a predetermined set time.

  In the above example, the speed is decelerated during the conveyance of the registration roller. However, the present invention is not limited to this. First, the conveyance speed of the registration roller is low, and then the conveyance speed is accelerated halfway to this time. The time from T1 to time T3 can be set to a predetermined time.

  Next, a control example of the image forming apparatus according to the third embodiment will be described. FIG. 9 is a flowchart for explaining a control example according to the third embodiment.

  As an example, when two originals, double-sided printing mode, recording paper size A3, number of transfers n = 200 (corresponding to 100 recording papers) are selected, the paper feed parameters are obtained using the above-mentioned table, and continuous printing is performed. I will explain.

  In FIG. 9, in S31, the duplex display mode, the recording paper size A3, and the number of transfers n = 200 are input from the operation display means 60 (FIG. 1).

  In S32, after the original is read, the recording paper P is conveyed from the paper feed cassette 20 (FIG. 1), and the recording paper P passes by the transfer number integrating means 80 (FIG. 2) provided near the registration roller 23. Then, the transfer number n is counted.

  In S33, it is determined whether or not the transfer number n exceeds the set transfer number n = 200. If not, the process proceeds to S34, and if it exceeds, the job ends here.

  In S34, it is determined whether or not the number n of times of transfer exceeds the sorting area of the number of times of transfer n in the table. If not, the process proceeds to S35, and the recording paper P is conveyed by the rotation of the registration roller 23, and in S38. The toner image on the image carrier is transferred to the recording paper P at the transfer position, fixed, and the process returns to S32.

  If it is determined in S34 that the number of times of transfer n exceeds the segmented area, the process proceeds to S36, where the registration roller deceleration timing (time ΔT2 in FIG. 8) is obtained from the above-mentioned table, and the registration roller deceleration timing is determined in S37. It is made earlier by ΔT2 than the reference deceleration timing T2. Thereafter, in S35, the recording paper P is conveyed by the rotation of the registration roller 23. In S38, the toner image on the image carrier is transferred to the recording paper P at the transfer position, fixed, and the process returns to S32.

  As described above, according to the present invention, during continuous printing, the influence of heat is prevented by simple control, and the toner image carried on the image carrier is placed at a predetermined position on the recording paper at the transfer position. You can transfer. In addition, the feeding parameter can be easily obtained.

  In the first to third embodiments, the example in which the paper feed parameter is obtained by using the table has been described. However, the present invention is not limited to this, and a method of obtaining from a calculation formula obtained in advance without using the table may be used. Needless to say.

  Further, in the first to third embodiments, the double-sided / single-sided distinction and the size of the recording paper have been described as the job setting contents. However, the present invention is not limited to this. For example, the type of recording paper (thick paper, plain paper) , Thin paper, etc.) may be added.

  Furthermore, the case where an intermediate transfer member (image carrier) is used as an example of the image forming apparatus according to the first to third embodiments has been described. However, the present invention is not limited to this configuration. For example, an intermediate transfer member is used. Needless to say, the present invention can also be applied to an image forming apparatus using only a photosensitive drum as an image carrier.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a diagram for explaining a recording paper conveyance mechanism in FIG. 1. 2 is a block diagram of a control system according to Embodiment 1. FIG. 4 is a table for obtaining a feeding parameter according to the first embodiment. 4 is a flowchart for explaining a control example according to the first embodiment. 10 is a table for obtaining a feeding parameter according to the second embodiment. 10 is a flowchart for explaining a control example according to the second embodiment. FIG. 10 is a diagram for explaining a registration roller deceleration method according to the third embodiment. 10 is a flowchart for explaining a control example according to the third embodiment.

Explanation of symbols

6 Image carrier 7A Transfer means 23 Registration roller 70 Control means 73 RAM (Storage means)
80 Transfer count integration means TL1, TL2 Table P Recording paper n Transfer count

Claims (7)

An image carrier;
Transfer means for transferring a toner image carried on the image carrier onto a sheet-like recording paper at a transfer position;
A registration roller that conveys the recording paper toward the transfer position;
Transfer number integration means for integrating the number of transfers of the toner image transferred to the recording paper at the transfer position from the start of the job;
Storage means for storing the accumulated number of transfers and job settings;
At the time of continuous printing, based on the recorded number of times of transfer and the set content, the conveyance time from the recording paper conveyance start position by the registration roller to the transfer position is matched with a predetermined set time. Control means for controlling the driving of the registration rollers;
An image forming apparatus comprising: The control means obtains a paper feed parameter corresponding to the recorded number of times of transfer and the set content, and controls the number of rotations of the registration roller per unit time based on the obtained paper feed parameter. Item 2. The image forming apparatus according to Item 1. The control unit obtains a paper feed parameter corresponding to the recorded number of times of transfer and the set content, and controls a recording paper conveyance start timing by the registration roller according to the obtained paper feed parameter. Item 2. The image forming apparatus according to Item 1. 2. The control unit according to claim 1, wherein a sheet feeding parameter is obtained corresponding to the recorded number of times of transfer and the set content, and the deceleration or acceleration timing of the registration roller is controlled by the obtained sheet feeding parameter. The image forming apparatus described in 1. 5. The control unit according to claim 2, wherein the control unit includes a table in which the number of times of transfer, the setting content, and the paper feed parameter are associated with each other, and obtains a paper feed parameter using the table. The image forming apparatus described. The image forming apparatus conveys an image carrier on which toner images carried on a plurality of photosensitive drums are transferred by a conveyance belt, and transfers the toner image carried on the image carrier onto a recording sheet at a transfer position. The image forming apparatus according to claim 1, wherein an image of caulking color is formed. The image forming apparatus transfers the toner image carried on the image carrier onto the recording paper conveyed by the rotational drive of the registration roller when the double-sided printing mode for creating images on both sides of the recording paper is selected. The recording paper is reversed by a reversing and conveying means, guided again to the registration roller, and a new toner image carried on the image carrier is controlled to be transferred to the other surface of the recording paper. The image forming apparatus according to claim 6.

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