JP2006043921A - Double-sided optional unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform correction free from image lack by arranging a sheet gap sensor for correcting sheet end gap occurring at the time of perfecting printing in a double-side optional unit and specifying the conditions of arranging position of the sensor. <P>SOLUTION: Position of a sheet gap sensor 9 is set such that the time required for a sheet to arrive at an image transfer position in an image forming apparatus 4 after sheet gap is detected by the sheet gap sensor 9 in a double-sided optional unit 5 becomes longer than the total sum of the time required for the image forming apparatus to perform correction processing of image data with reference to a gap calculated based on the detection results from the sensor 9 and the processing time required for a toner image corresponding to the corrected image data to reach the transfer position. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a double-sided option device applied to an image forming apparatus that forms an image on a recording medium, and more particularly, to a double-sided optional device that can appropriately perform a correction process for a positional deviation of the recording medium.

  Conventionally, when an image forming apparatus transports a sheet from a sheet, a cassette, or a tray that is re-fed from a duplex conveyance path to a registration roller position, the sheet is displaced in a direction (main scanning direction) perpendicular to the conveyance direction. In the case where the sheet is conveyed while the image is generated, an apparatus that does not include a mechanism for correcting a printed image in the process up to the development forms an image in which a paper shift occurs in the main scanning direction.

  In order to prevent the above-described paper position deviation from occurring, it has been proposed to provide a reference guide plate 42 along one side of the conveyance path and to follow the reference guide plate 42. This proposal will be described with reference to FIG.

  In order to correct such a deviation, a skew roller 40 is used to forcibly convey along the reference guide plate. A sheet is fed from a pickup roller 41 that picks up the sheet, and the sheet is conveyed along the reference guide plate 42. It is necessary to manually change the lever of the reference guide plate 42 according to the paper. The sheet edge is regulated by the reference guide plate. When the picked up paper is conveyed, it passes through the skew roller 40. At that time, the skew roller 40, to which a predetermined tension is applied so that the sheet follows the reference guide plate 42, is attached to the shaft at a slant. The sheet is smoothly conveyed by the skew roller 40, and the sheet is regulated by the reference guide.

  Further, in order to correct such misalignment, in Patent Document 1, a sensor that detects a sheet misalignment amount in a direction orthogonal to the sheet transport direction is installed on the sheet transport path, and a sensor that detects a sheet misalignment at the end of the transported sheet is used. There has been proposed a method of calculating a deviation amount based on the result of the above and correcting the image writing position based on the calculated data.

JP 2002-292960 A

  However, in the method of conveying and feeding the paper along the guide plate, it is necessary to hold the paper so that the paper does not fall under its own weight in the so-called vertical method. Further, in Patent Document 1, there is no mention of the arrangement and timing of the sensor and image writing locations, and the provisions of the system configuration (main body and optional configurations) of the image forming apparatus. For example, the sensor that detects the paper misalignment is most effective when used to correct the print position misalignment between the front and back of the image. When the paper misalignment detection sensor is disposed in the image forming apparatus, the double-sided optional device is used. The original and effective usage is when the printer is mounted and printed on both sides.

  However, a user who uses only single-sided printing in this configuration does not need a paper misalignment detection sensor, which increases the cost of the image forming apparatus main body.

  Also, when the printing speed of the device increases due to minor changes or when the double-sided optional device is diverted to multiple image forming devices, the paper misalignment detection sensor is placed at restricted or specified locations, so The path may be shortened, and there is a problem that the sheet conveyance time is shortened and the correction process cannot be performed before the back side printing is started.

  Furthermore, taking this into account, if the location of the paper misalignment detection sensor is moved significantly upstream in the paper transport direction, paper misalignment will occur again due to slanting etc. during paper transport from the sensor location to the print position. Accurate image correction may not be possible.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a double-sided optional device in which a paper misalignment detection sensor is arranged in a double-sided optional device and image forming can be performed by appropriately performing correction processing for the paper misalignment.

  Another object of the present invention is to reduce the cost of the image forming apparatus main body by disposing a paper misalignment detection sensor in the double-sided optional device.

  Furthermore, another object of the present invention is to perform image forming by properly performing correction processing on paper misalignment even when the printing speed of the image forming apparatus is increased or when the double-sided option apparatus is diverted to a plurality of image forming apparatuses. It is to provide a double-sided optional device that can be made possible.

  The present invention relates to a double-sided option device that inverts a recording medium after printing an image on one side and supplies the recording medium to an image forming apparatus, in a direction orthogonal to the recording medium conveyance direction on a recording medium conveyance path in the double-sided option device. A recording medium position deviation detecting means for detecting a position deviation of the recording medium; and a calculating means for calculating a position deviation amount of the recording medium based on a detection result from the position deviation detecting means, wherein the recording medium position deviation detection is provided. The time from the detection by the means until the recording medium reaches the image recording position on the recording medium in the image forming apparatus is calculated by the calculation means after the detection by the recording medium position deviation detection means. By referring to the positional deviation amount of the recorded recording medium, the time for correcting the image data in the image forming apparatus and the recording material image corresponding to the corrected image data are displayed in advance. The position of the recording medium position deviation detection means in the transport direction of the recording medium transport path in the double-sided optional device is set so as to be longer than the sum of the processing time until the image recording position is reached. It is characterized by.

  According to the present invention, the double-sided optional device is provided with the recording medium position deviation detecting means, and after the timing when the image data corrected by using the detection result from the recording medium position deviation detecting means is finished forming on the image recording means. Since the recording medium detected by the recording medium position deviation detecting means reaches the image recording position by the image recording means, an image can be appropriately formed on the recording medium.

Example 1
FIG. 2 is a block diagram illustrating the configuration of the control system of the image forming apparatus 4 and the double-sided option apparatus 5 according to the first embodiment. The image forming apparatus 4 includes an engine controller 20 that performs an image forming process, and a printer controller 22 that processes image data therein. The double-sided option device 5 has a double-sided option controller 21 for driving both sides of the paper and detecting paper misalignment. In the engine controller 20, reference numeral 15 denotes CPU_A, which controls printing of the image forming apparatus 4. A ROM 19 stores a control program and control table for the CPU_A15. The CPU_A 15 controls each component of the engine controller 20 according to the control program in the ROM 19. Reference numeral 16 denotes a communication means A, which communicates with the CPU_B27 of the double-sided option controller 21 via the communication means B26. Reference numeral 10 denotes a pre-registration sensor, which is a sensor that detects the leading edge of the paper in order to align the paper with the registration rollers. A laser drive circuit 17 irradiates a laser according to image data from the printer controller 22. An I / O port 18 is provided between the pre-registration sensor 10 and the CPU_A 15 and between the CPU_A 15 and the laser drive circuit 17. A sensor 9 detects a misalignment of the main scanning paper position, and detects a registration position of the paper in the main scanning direction. The detected misalignment position is detected by the CPU_B27 and is calculated by the signal processing means 29 as the misalignment amount from the sheet edge. The calculated deviation amount is first transmitted to the CPU_A15 of the engine controller 20 by the communication means B26 and communication means A16, and then transmitted to the image control means 24 of the printer controller 22 by the communication means C23 and communication means D43, and the image control means 24 Thus, the image writing position control to the photosensitive drum 6 described later is performed according to the transmitted deviation amount. Reference numeral 28 denotes a RAM, which is used as a working memory for the CPU_B27. Reference numeral 27A denotes a ROM which stores a control program and a control table for the CPU_B27. The CPU_B 27 controls each component in the double-sided option controller 21 according to the control program in the ROM 27A. Reference numeral 25 denotes a conveyance driving unit that drives the reversal of the sheet conveyed to the duplex option device 5, conveyance, and refeeding to the image forming apparatus. The conveyance sensor 11 is a sensor provided in the double-side conveyance path and detects the conveyance of the paper.

  Next, the printing operation will be described with reference to FIG. The double-sided option device 5 can be easily set, for example, by the user with respect to the image forming apparatus 4, and can be removed. Since the sheet misalignment detection sensor 9 is attached to the duplex option device 5, the cost of the image forming apparatus 4 can be reduced.

  The CPU_B 27 of the engine controller 20 starts printing by the image forming apparatus 4 when a print start command is sent from the printer controller 22. Next, the laser drive control circuit 17 is activated by the image data sent from the printer controller 22, and the laser is irradiated from the laser scanner 2 to the photosensitive drum 6 uniformly charged by the charging roller 7. Further, a toner (not shown) image is visualized on the photosensitive drum 6 by the developing device 3. At the same time, the paper set in the paper feed cassette 8 is guided to the transport path by the pickup roller, the leading edge is detected by the pre-registration sensor 10, and after the registration is taken, it is nipped by the transfer roller 1. Then, the developed toner is transferred to the photosensitive drum 6. Next, the trailing edge of the sheet passes through the fixing roller pair 13 and is detected by the fixing discharge sensor 12. After the trailing edge of the paper is detected, the paper is reversely driven by the switchback method to be printed on the double-sided option device in order to print the back side. The leading edge of the sheet is detected by a conveyance sensor 11 installed on the conveyance path of the duplex option device. After a predetermined timing after the leading edge of the paper is detected by the transport sensor 11, the paper deviation detection sensor 9 detects the paper deviation.

  After detecting the sheet misalignment position, the sheet is fed again to the image forming apparatus 4. In the double-sided option controller 21, the amount of deviation is calculated by the signal processing means 29 from the paper deviation position detected by the paper deviation detection sensor 9, and is transmitted to the printer controller 22, and then the paper deviation is detected by the image control means 24. Corrected image data is generated, and then the engine controller 20 starts controlling laser irradiation based on the corrected image data. The sheet re-fed from the duplex option device 5 to the image forming apparatus 4 is printed on the back side and fixed, and then discharged to the sheet discharge tray.

  FIG. 6 is a schematic perspective view for explaining a paper misalignment detection mechanism including a light emitting element 35 and a light receiving element 37 constituting a paper misalignment detection sensor, and is attached to a corresponding position of the left end portion of the paper in the paper transport path. . As shown in FIG. 6, a light emitting element 35 serving as a light emitting portion is disposed above the portion corresponding to the paper edge of the paper transport path, and a light receiving element 37 serving as a light receiving portion is disposed below the portion. The end of the sheet conveyed between the light emitting element 35 and the light receiving element 37 is positioned. Further, even if the light emitting element 35 and the light receiving element 37 are arranged upside down, they function similarly.

  FIG. 5 is a diagram illustrating a configuration of the paper misalignment detection sensor. As shown in the figure, the light emitting element 35 has a light guide 38 that uniformly irradiates light from the LED 36. The light receiving element 37 is generally composed of a large number of photodiodes arranged on a straight line. The output of each photodiode on the light receiving side that is sequentially output in response to a clock described later is “OFF” when the light from the light emitting side is blocked by the paper. The position of the photodiode where “OFF” is switched will change. By detecting the change point of the output from this sensor, it is possible to detect the edge of the sheet.

  FIG. 4 shows a specific circuit block diagram of paper edge detection. In the detailed configuration of the signal processing means 29 in the double-sided option controller 21 shown here, the CPU_B27 is turned “ON” when the paper is fed, the LED 36 is driven, and the light guide 38 irradiates light uniformly. Light is received by the light receiving surface of the element 35.

  A CLK signal and a reset signal (RST), which are reference signals, are sent from the timing signal generation unit 32 to the light receiving element 37. Each time each clock signal is input, the output from each photodiode constituting the light receiving element 35 is sequentially output in the arrangement order. As a result, a predetermined analog signal whose output level varies depending on whether or not the light from the light guide 38 is blocked by the paper can be obtained as the output of the light receiving element 35. The analog signal is input to the comparator 34 and binarized by a predetermined threshold. The output of the comparator 34 is input to the enable (EN) terminal of the counter 33. Here, the timing waveform of the paper edge detection circuit shown in FIG. 4 will be described with reference to FIG. Here, the case where the light on the light receiving surface is blocked by the paper is described as logic that counts as “OFF” time. The counter 33 shown in FIG. 4 is initialized to “0” every time the reset signal (RST) output from the timing signal generator 32 is “L”. Thereafter, the reset signal (RST) is set to “H”, and when the signal logic (EN) from the comparator 34 is inputted to “H”, it counts up in synchronization with the reference CLK. When CLK reaches the edge of the sheet, an analog signal is output from the light receiving element 37, so the output (EN) of the comparator 34 becomes “L” and is held at the count value in synchronization with the reference CLK. Here, for the sake of convenience, a count-up operation from “0” to n is shown. Thereafter, the value held by the counter 33 will be described again with reference to the circuit block diagram of FIG.

  The count value held here is subjected to arithmetic processing by the CPU_B27, the amount of paper misregistration is calculated, and transmitted to the engine controller 20 and further to the printer controller 22 through the communication means B25 and communication means A16. The printer controller 22 receives the transmitted calculated value, controls the image writing position by the image control means, and sends the image to the engine controller 20.

  Next, the state of image correction will be described with reference to FIG. FIG. 10 illustrates an example in which paper misalignment is detected at the left end of the paper and the paper misalignment occurs in the right direction. It is assumed that the laser scanner is configured to scan from left to right. When the misalignment occurs, the image is corrected by starting to write the image from the position where the misalignment detected by the misalignment position detection sensor and the margin from the left end of the sheet are added to the original left end of the sheet. It is possible to print at the same position as when no paper misalignment occurred.

  Next, an operation from detection of a paper misalignment position to image printing will be described with reference to FIG. 3 which is a timing chart.

  As shown in (1), the conveyance sensor 11 is arranged inside the double-sided option device 5 and becomes “H” when a sheet conveyed inside the double-sided option 5 is detected. When the transport sensor 11 rises to “H” and a predetermined timing has passed, the paper is transported to the attachment position of the paper misalignment detection sensor 9, so that the duplex option controller 21 outputs the paper misalignment detection sensor 9 as shown in (2). Start importing. When the capture of the output of the paper misalignment detection sensor 9 is completed, the paper edge misalignment amount is calculated based on this and transmitted to the printer controller 22. As shown in (5), the printer controller 22 executes image position correction processing based on the transmitted sheet misalignment amount. In the image correction process (5), “H” is set during the processing operation and “L” is set during the pause.

  The sheet whose amount of deviation of the sheet edge is detected is further conveyed and fed again from the duplex option device 5 to the image forming apparatus 4, and the conveyance driving is continued inside the image forming apparatus 4. (3) is the output of the pre-registration sensor 10, and the sheet is detected with “H”. The leading edge of the conveyed paper is detected by the pre-registration sensor 10 and the driving is temporarily stopped to form a loop. Thereafter, as shown in (4), the leading edge registration is performed by starting the re-driving. When the image correction corresponding to the paper misalignment is completed from the printer controller 22, the corrected image data is transmitted to the engine controller 20. As shown in (6), the engine controller 20 drives the laser based on the image data and starts irradiating the photosensitive drum 6 with the laser. After the start of laser irradiation, the toner is transferred to the back side of the paper conveyed from the double-sided option device 5 at the transfer position through a development process.

The paper misalignment detection sensor 9 is arranged such that the electrophotographic process speed is V1, the paper transport speed is V2, and the paper misalignment detection sensor 9 detects the paper misalignment position and then transports it to the transfer position where the toner image is transferred to the paper. T2 is the time required to complete the image correction after processing the paper misalignment after the paper misalignment position is detected, and the toner image transfer position from the start of laser irradiation to the toner image transfer position is developed. T3 is the time required for processing until the toner image arrives
Arrangement so that V2t2> V2t1 + V1t3 is a necessary condition.

  That is, the time from the detection by the paper misalignment detection sensor to the arrival of the paper at the image recording position on the paper in the image forming apparatus is detected by the signal processing means after the detection by the paper misalignment detection sensor. The sum of the time for correcting the image data in the image forming apparatus with reference to the calculated amount of positional deviation of the paper and the processing time until the recording material image corresponding to the corrected image data reaches the image recording position Thus, the position of the paper misalignment detection sensor in the transport direction of the paper transport path in the double-sided optional device is set. As a result, an image can be appropriately formed on the paper.

(Example 2)
The second embodiment will be described with reference to FIGS.

  9 is a cross-sectional view of the overall configuration of the apparatus according to the second embodiment, and FIG. 11 is an electrical block diagram of the second embodiment. The same configuration as that of the first embodiment is the same operation, and the same reference numerals are given and the detailed description is omitted.

  Reference numeral 30 denotes a carriage for allowing the paper misalignment detection sensor 9 to move in the transport direction. The carriage 30 is driven by carriage driving means 44. The carriage driving means 44 has a pulse motor (not shown), and is controlled to move to a conveyance position in an arbitrary sheet conveyance direction based on pulse data from the CPU_B27. A carriage home position sensor 31 is installed at the initial position of the carriage, detects the initial position of the carriage 30, and outputs it to the CPU_B27. In FIG. 11, reference numeral 43 denotes table conversion means, and the sheet conveying speed and electrophotographic process speed of the image forming apparatus corresponding to the model code transmitted from the engine controller 20, and the sheet is conveyed to the toner image transfer position after detecting the sheet misalignment. Data that the CPU_B27 refers to to calculate the carriage movement position, which will be described later, for the time required, the time required for image correction made according to paper misalignment, and the time required for processing from the start of laser irradiation to the toner image transfer position to the paper Stores the table to convert.

  Next, the operation of the second embodiment will be described. The CPU_B 27 of the duplex option controller 21 acquires the model code of the image forming apparatus 4 from the engine controller 20 and recognizes the model of the image forming apparatus 4 to be mounted. Next, the CPU_B27 detects the sheet conveyance speed V2, the electrophotographic process speed V1, and the time t2 required to convey the sheet to the toner image transfer position after the sheet deviation is detected from the table conversion unit according to the recognized model. The paper misalignment detection sensor 9 is obtained by acquiring the time t1 required until the end of image correction in response to the paper misalignment and the time t3 required for the processing from the start of laser irradiation until the toner image reaches the toner image transfer position on the paper. The carriage driving means 44 is driven to move the carriage 30 so as to move to a detection position where a predetermined condition is satisfied. The predetermined condition is that V2t2− (V2t1 + V1t3) = T is satisfied, where T provides a minimum margin, and from the detection of the paper misalignment detection sensor 9 to the toner image transfer position to the paper. This constant is set in order to shorten the conveyance path as much as possible. That is, the CPU_B 27 detects the paper misalignment based on the time from the paper detection timing of the transport sensor 11 to the detection timing of the paper misalignment detection sensor 9 and the paper transport speed of the duplex option device 5 so that the predetermined condition is satisfied. The position of the sensor 9 is calculated, and the carriage drive unit 44 is controlled based on the calculation result to move the carriage 30 to the calculated position.

  In FIG. 9, as an example, the paper misalignment in the double-sided option device 5 when at least one of the paper transport speed and the electrophotographic process speed is installed in three image forming apparatuses A, B, and C different from other image forming apparatuses. The arrangement position of the detection sensor 9 is indicated. As described above, by enabling the paper misalignment detection sensor 9 to move on the paper transport path in the double-sided optional device 5, a plurality of images in which at least one of the paper transport speed and the electrophotographic process speed is different from those of other image forming apparatuses. It becomes possible to deal with the positional deviation of the paper by sharing the duplex option device 5 with the forming apparatus.

1 is a cross-sectional view of a device according to Embodiment 1 of the present invention. 1 is an electrical block diagram of Embodiment 1 of the present invention. FIG. 6 is a timing chart illustrating a paper misalignment correction operation according to the first exemplary embodiment of the present invention. FIG. 6 is a block diagram illustrating a paper misalignment detection process according to the first exemplary embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a paper misalignment detection sensor according to the first exemplary embodiment of the present invention. FIG. 3 is a schematic perspective view illustrating a paper misalignment detection mechanism according to the first exemplary embodiment of the present invention. It is a figure explaining the image which regulates the paper position in a prior art example to a standard guide board. FIG. 6 is a diagram illustrating a timing chart of a paper edge misalignment detection process according to the first exemplary embodiment of the present invention. It is apparatus sectional drawing of Example 2 of this invention. FIG. 6 is a diagram illustrating a paper misalignment correction operation according to the first exemplary embodiment of the present invention. It is an electrical block diagram of Example 2 of the present invention.

Explanation of symbols

1. Transfer roller 2. Laser scanner 3. Developing unit 4. Image forming device 5. Double-sided optional device 6. Photosensitive drum 7. Charging roller 8. Feed cassette 9. Paper misalignment detection sensor 10. · Pre-registration sensor 11 ·· Conveyance sensor 12 ·· Fixing discharge sensor 13 ·· Fixing roller pair 14 ·· Discharge sensor 15
16 .... CPU_B
17. ・ Laser drive circuit 18 ・ I / O port 19 ・ ROM
20. Engine controller 21. Double-sided option controller 22. Printer controller 23. Communication means C
24..Image control means 25..Conveyance drive means 26..Communication means B
27 ・ ・ CPU_B
28..RAM
29 .. Signal processing means 30... Carriage 31... Carriage home position sensor 32. Timing signal generator 33. Counter 34. Comparator 35.
37 ·· Light receiving element 38 · · Light guide 39 · · Paper 40 · · Skew roller 41 · · Pickup roller 42 · · Reference guide plate 43 · · Carriage drive means 44 · · Table conversion means

Claims (3)

A double-sided optional device that inverts a recording medium after printing an image on one side and supplies it to an image forming apparatus,
A recording medium positional deviation detecting unit for detecting a positional deviation of the recording medium in a direction orthogonal to the recording medium conveying direction on the recording medium conveying path in the double-sided optional device, and the recording based on a detection result from the positional deviation detecting unit. A calculating means for calculating the amount of positional deviation of the medium,
The time until the recording medium reaches the image recording position on the recording medium in the image forming apparatus after the detection by the recording medium position deviation detecting means is detected by the recording medium position deviation detecting means. The image forming apparatus refers to the amount of positional deviation of the recording medium calculated by the calculating means from the time and the recording material image corresponding to the corrected image data reaches the image recording position. The position of the recording medium position deviation detecting means in the transport direction of the recording medium transport path in the double-sided optional device is set so as to be longer than the sum of the processing time until Optional device. In claim 1,
The double-sided option device characterized in that the positional deviation detection means can change the position of the recording medium conveyance path in the conveyance direction. In claim 2,
The double-sided optional device characterized in that the position of the misregistration detection means in the conveyance direction of the recording medium conveyance path is determined based on at least the process speed of the image forming apparatus and the conveyance speed of the recording medium.

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