JP2013105040A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause a reference mark on an intermediate transfer belt to stop at a position immediately before a detection position of a sensor.SOLUTION: An image forming apparatus employing an indirect transfer system includes: an intermediate transfer belt 15; a reference mark 19 that may be any icon arranged on the intermediate transfer belt 15; a detection sensor 18 that reads the reference mark 19 before image formation onto the intermediate transfer belt 15; and transfer belt drive means 20 for rotating the intermediate transfer belt 15 after the image formation such that the reference mark 19 is located immediately before a detection position by the detection sensor 18.

Description

  The present invention relates to an image forming apparatus, and more particularly to an indirect transfer type image forming apparatus.

  In the technical field of indirect transfer type image forming apparatuses, it is one of important issues to make the intermediate transfer belt usable for a long period of time. Japanese Patent Laid-Open No. 2004-228867 aims to extend the life of the intermediate transfer belt, and based on the detection of the reference mark provided on the endless intermediate transfer belt, the exposure start time from the detection time when the reference mark is detected. A configuration is disclosed in which the exposure timing time until is changed in accordance with the cumulative value of the number of printed sheets by the number counter that measures the number of printed sheets and the cumulative value of the number of printed dots by the dot counter that measures the number of printed dots.

  However, in Patent Document 1, depending on the size of the printing paper and the deviation of the printing dots, there is a possibility that the usable life remains on the intermediate transfer belt and is replaced as it has reached the end of its life. .

  In an electrophotographic image forming apparatus, as a means for transferring an image onto a sheet, a photosensitive drum is uniformly charged by a charger, and a latent image formed by irradiating the photosensitive drum with a laser is developed with toner. A technique (indirect transfer method) has been established in which an image formed on the intermediate transfer belt is transferred to a sheet fed to a transfer roller by transferring the image onto the intermediate transfer belt.

  During execution of the transfer means, the intermediate transfer belt is worn and soiled with use. When these stains become prominent, the printed image is affected. Therefore, the intermediate transfer belt is determined to have reached the end of its life by some method and replaced. However, for example, depending on how the user uses the image forming apparatus, there is a possibility that the contamination is accumulated locally only at a specific position on the intermediate transfer belt and the other positions are not contaminated. . Therefore, a technique for shifting the image transfer timing to the intermediate transfer belt by using the number of printed sheets or the number of printed dots is considered (for example, Patent Document 1).

  However, the conventional technology for shifting the image transfer timing to the intermediate transfer belt has not been sufficiently considered in that there are remaining image transferable portions. Specifically, for example, in the technique of simply shifting the image transfer position by the number of printed sheets, when A3 size paper and A4 size paper are printed on the same number of sheets, it is naturally better to print on A3 size paper. The range of contamination on the intermediate transfer belt increases. In that case, when the image transfer position is shifted in accordance with the A3 size, if the user is a user who uses only the A4 size, an untransferred area occurs.

  In the technique of simply shifting the image transfer position by the number of printing dots, even if the number of dots is the same, if the positions of the dots on the image are different, the fouling positions on the intermediate transfer belt are naturally different. In other words, the image transfer timing to the intermediate transfer belt has been shifted, but depending on the size of the printing paper and the printing dots, the service life has been reached with the usable portion remaining on the intermediate transfer belt. Will be exchanged as.

  In order to solve such problems, the intermediate transfer belt is divided into strips or blocks, and the degree of fouling / wearing is measured for each divided region, which is optimal for extending the life of the intermediate transfer belt. A technique has been proposed in which a location is specified, an exposure time is calculated based on the detected position of a reference mark, and printing is performed at an optimal transfer position. However, this technique also has a problem in that it takes time to rotate the reference mark from the stop position to the detection position for detecting the reference mark, and the printing time becomes long.

  The reference mark is a mark that is arranged in advance at an arbitrary position of the endless intermediate transfer belt. As a result, the position can be specified by the relative positional relationship from the reference mark at any location on the surface of the belt that is plain. The reference mark is detected by optically reading the reference mark with a sensor at any position on the intermediate transfer belt. Considering that the position of the sensor is used for subsequent processing such as calculation of exposure time, it is preferable that the position of the sensor is upstream of the exposure unit and the photosensitive member and downstream of the secondary transfer roller pair.

  Since the image forming apparatus is not always in operation, the intermediate transfer belt may also stop rotating and the reference mark may stop somewhere on the intermediate transfer belt. However, in this case, depending on the stop position of the reference mark, the distance to the detection position by the sensor becomes very long. For example, if the stop position of the reference mark is immediately after the detection position of the sensor, the reference mark needs to make a round of the intermediate transfer belt. The closer the stop position of the reference mark is to the detection position by the sensor, the shorter the time required for image formation.

  The reference mark was provided for the purpose of helping to identify a specific area on the intermediate transfer belt (such as an area considered to be less contaminated or worn). However, other uses are possible unless there is a particularly reasonable reason to limit to this purpose.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus capable of setting the stop position of the reference mark on the intermediate transfer belt immediately before the detection position of the sensor. .

  In order to achieve the above object, the present invention provides an indirect transfer type image forming apparatus comprising an intermediate transfer belt, a reference mark that is an arbitrary image arranged on the intermediate transfer belt, and the reference mark. A detection sensor that reads before image formation on the intermediate transfer belt, and a transfer belt driving unit that rotates the intermediate transfer belt after image formation so that the reference mark is positioned immediately before the detection position by the detection sensor. An image forming apparatus is provided.

  According to the present invention, the stop position of the reference mark on the intermediate transfer belt can be set immediately before the detection position of the sensor.

FIG. 2 is a block diagram showing a configuration of a control system of the image forming apparatus according to the embodiment of the present invention. It is the schematic which shows the mechanical structure of the principal part of the said embodiment. 6 is a flowchart illustrating a flow of a primary transfer process in which an image is formed by selecting an area with less fouling and wear in the embodiment. It is explanatory drawing of the calculation formula and parameter of exposure start time in FIG. It is a flowchart which shows the flow of operation | movement of the said embodiment. It is a figure for demonstrating the processing content of S111 of FIG. It is a flowchart which shows the detailed flow of a process of S111 of FIG. It is a figure for demonstrating the processing content of other Embodiment 2 of this invention. 10 is a flowchart illustrating a detailed flow of processing according to the second exemplary embodiment. It is a figure for demonstrating the processing content of other Embodiment 3 of this invention. It is a flowchart which shows the flow of the process of other Embodiment 4 of this invention. It is a flowchart which shows the flow of the process of other Embodiment 5 of this invention.

  Embodiments of the present invention will be described below. The following Embodiments 1 to 5 have the following characteristics in the image transfer position control process on the intermediate transfer belt. In short, since the reference mark is stopped just before the detection sensor before printing, the movement distance from the reference mark stop position to the detection sensor is short at the start of printing, so the reference mark detection time is shortened and the printing time is reduced. It can be shortened. Hereinafter, this feature will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a configuration of a control system of the image forming apparatus according to the present embodiment. This image forming apparatus shown in FIG. 1 is an MFP (multifunction multifunction peripheral), and includes an engine unit 201 and a controller unit 202 (image processing apparatus). Note that another image forming apparatus such as a laser printer, a digital copying machine, or a facsimile apparatus may be used instead of the MFP.

  The engine unit 201 includes a scanner 101, a plotter 102, a reading control unit 103, a writing control unit 104, an engine control CPU 105, and the like. The engine unit 201 corresponds to the apparatus main body. A scanner 101 is an image reading unit that reads an image of a document.

  The plotter 102 receives the image data developed in the memory 115 of the controller unit 202 via the ASIC 112 and the writing control unit 104, and prints (forms) a toner image as a visible image on a recording sheet (or other recording material). An image forming unit (image forming unit) and a fixing unit (fixing unit) that heats and fixes the toner image formed on the recording paper by the image forming unit. The image forming unit is equipped with an optical writing device capable of outputting, for example, four-color laser beams of Y (yellow), M (magenta), C (cyan), and B (black). Note that writing of an image with a laser beam from an optical writing device in the image forming unit is well known, and thus details thereof are omitted. Each of the image forming unit and the fixing unit may include three or more.

  A reading control unit 103 controls reading of a document image by the scanner 101. The writing control unit 104 is a writing control unit (writing control device) that controls the optical writing device in each image forming unit provided in the plotter 102. The engine control CPU 105 performs overall control of each part of the engine unit 201 by operating according to a program in a ROM (not shown).

  The controller unit 202 includes a controller control CPU 111, an ASIC 112, an operation unit 113, an HDD 114, a memory 115, a network interface (hereinafter, “interface” is also referred to as “I / F”) 116, and the like. Note that the operation unit 113 is actually disposed outside the controller unit 202.

  The controller control CPU 111 performs overall control of each unit of the controller unit 202 by operating according to a fixed program in a ROM (not shown) and a program developed on the memory 115. The ASIC 112 is a multi-function device board, which shares devices to be controlled by the controller control CPU 111, and supports high efficiency of development of application programs and the like from the viewpoint of architecture.

  The operation unit 113 includes various operation keys (also referred to as operation switches or operation buttons) for inputting data such as operation instructions for the engine unit 201 based on selection of an image processing function provided by the image forming apparatus, an LCD, or a CRT. And so on. The HDD 114 is a non-volatile storage unit (storage device) that stores and holds a large amount of data, and can store programs including an OS (operating system), various setting data, and various data such as image data. Note that data in the memory 115 can be stored in the HDD 114. Further, a non-volatile memory may be provided and various setting data may be stored therein.

  The memory 115 is a storage unit such as a program memory that stores various programs, a work memory that is used when the controller control CPU 111 performs data processing, and a RAM that is used as an image memory that develops image data. The network I / F 116 is for communicating with an external device such as a personal computer via a network (not shown).

  Here, there are various image data to be printed, such as read data from the scanner 101 (RGB image data), input data from the network I / F 116, and accumulated data in the HDD 114. In the case of (full color), the image data of each color plate of YMCB is converted in advance to the image data of monochrome (gray scale) in the case of monochrome, and developed in the memory 115.

  In the image forming apparatus configured as described above, the controller control CPU 111 of the controller unit 202 reads out various programs including the OS (operation system) and application software in the HDD 114 according to the boot program in the ROM when the power is turned on. After being developed on 115, it operates according to its various programs (various programs are selectively executed as necessary), and controls the apparatus to control the reference on the intermediate transfer belt relating to the main part of the present embodiment. It is possible to realize a function of setting the mark stop position immediately before the detection position of the sensor.

  The image forming apparatus according to the present embodiment is a so-called indirect transfer system, and includes an intermediate transfer belt. Further, it is an electrophotographic system, and is a so-called tandem system having a plurality of photoconductors. FIG. 2 schematically shows the mechanical configuration of the main part of the present embodiment.

  As shown in FIG. 2, the intermediate transfer belt 15 is an endless belt stretched between a transfer belt driving roller 16 and a tension roller 14 biased outward. A secondary transfer roller 17 is disposed at a position facing the transfer belt drive roller 16. The photoconductors 10 are arranged from upstream to downstream in the rotation direction of the intermediate transfer belt 15.

  An electrostatic latent image is formed on the photosensitive member 10 by the charger 11 and the exposure device 12, and toner is attached by the developing device 13 to form an image. Further, the toner is transferred from the photoreceptor 10 to the intermediate transfer belt 15, and the toner is transferred from the intermediate transfer belt 15 to the sheet at a position where it contacts the secondary transfer roller 17. A reference mark 19 is provided on the intermediate transfer belt 15, and a detection sensor 18 is provided upstream of each color photoconductor 10. Based on the detection of the reference mark, the exposure timing to the photoconductor 10 is controlled.

  Hereinafter, the flow of processing up to the primary transfer in the image forming processing of the image forming apparatus shown in FIGS. 1 and 2 will be described. At this time, the flow of the process of forming an image by selecting an area where the intermediate transfer belt is less contaminated or worn will be described, in particular, in the primary transfer process.

  FIG. 3 shows the flow of the processing. As a premise of this processing, strip-shaped equally-spaced divided blocks are defined on the intermediate transfer belt 15 along the rotation direction of the intermediate transfer belt 15. During the printing operation, an optimum transfer position is determined from the divided blocks (S101 to S104), and the transfer is performed to that position (S105 to S108). At that time, based on the size data of the paper to be printed, the number of continuous blocks necessary to transfer the image onto the paper is calculated (S102, S103), and the optimum transfer position is determined based on the number of continuous blocks. (S104).

  After the optimum transfer position on the intermediate transfer belt 15 is determined, the reference mark 19 placed on the intermediate transfer belt 15 is detected by the detection sensor 18 (S105). After the detection, the exposure start time is determined by the following equation based on the optimum transfer position determined by the following equation (S106), and the image is transferred to the optimum transfer position on the intermediate transfer belt 15 by exposure. . The reference mark 19 is an arbitrary icon arranged on the intermediate transfer belt 15.

Calculation formula of exposure start time T (time from reference mark detection to exposure start) T = (P + Q−R) / V
However, the meaning of the parameters is as follows (see also FIG. 4).
P: Distance from the reference mark to the optimum transfer position on the intermediate transfer belt Q: Distance from the detection sensor to the contact position R: Distance from the exposure position to the contact position on the photoconductor V: Rotation of the intermediate transfer belt / photoconductor speed

  FIG. 4 is an explanatory diagram of calculation formulas and parameters of the exposure start time. FIG. 4 shows only the Y photoconductor, but the same applies to the other colors. Thus, by calculating the exposure start time and performing the image forming operation, the transfer can be accurately performed to the determined optimum transfer position.

  The time taken from S102 to S109 in the flowchart shown in FIG. 3 can be considered as the printing time of one printing sheet (strictly, to the primary transfer). The problem with the method described with reference to FIG. 3 is that it takes time to detect the reference mark 19 placed on the intermediate transfer belt 15 by the detection sensor 18 after the optimum transfer position on the intermediate transfer belt 15 is determined (S105). is there. Prior to the start of the detection operation, the reference mark 19 stops at an arbitrary position on the intermediate transfer belt 15 (this arbitrary position is referred to as a “stop position”), and in the worst case (the stop position is immediately after the detection sensor 18). From the stop position to the detection position of the reference mark 19, it takes time to rotate the belt once. This increases the printing time. If the rotation speed of the intermediate transfer belt 15 does not change, the detection time becomes shorter as the distance from the stop position to the detection position of the reference mark 19 is smaller.

  2 and 4 show a case where the reference mark 19 happens to be at the detection position of the detection sensor 18.

  In order to shorten the distance from the stop position to the detection position of the reference mark 19 before the start of the detection operation as much as possible, the reference mark 19 is stopped immediately before the detection sensor 18 after the completion of each printing operation (FIG. 5, S110, S111). Since the distance from the stop position of the reference mark 19 to the detection sensor 18 is short when the reference mark 19 is detected next time, it can be detected immediately by the detection sensor 18. The detection time as a part of the printing time is shortened, and the printing time can be shortened. FIG. 5 is a diagram illustrating a control flow from the start of the printing process to after the printing operation until the reference mark 19 is stopped immediately before the detection sensor 18.

  Hereinafter, a specific process of the process of stopping the reference mark 19 immediately before the detection sensor 18 after the printing operation (S111 in FIG. 5) will be described. FIG. 6 shows a diagram for explaining the processing content of S111 of FIG. FIG. 7 shows a detailed flow of the process of S111 of FIG. As shown in FIG. 6, the transfer belt drive roller 16 is rotationally driven by a transfer belt drive means 20 configured by a control system as shown in FIG. Further, the transfer belt driving unit 20 is controlled by a control unit 21 configured by a control system as shown in FIG.

  As shown in FIG. 6, a “setting stop position” is provided as a position at which the reference mark 19 is to be stopped after the end of each image formation at a position “distance X” away from the detection position by the detection sensor 18. The distance X is preferably as short as possible as long as any inconvenience does not occur in view of the purpose of the present embodiment in which the detection time of the reference mark 19 is desired to be shortened.

  After each printing process, the control means 20 uses the distance X from the position of the detection sensor 18 to the stop position and the rotational speed V so as to follow the rotational direction of the intermediate transfer belt 15, and rotates the following formula. Time T1 is calculated (S201 in FIG. 7).

T1 = (L−x) / V (1)
L: Length of the intermediate transfer belt 15 V: Rotational speed of the intermediate transfer belt 15

  The transfer belt driving unit 20 rotates the intermediate transfer belt 15 at the rotation speed V (S202). The reference mark 19 is detected by the detection sensor 18 (Yes in S203). When the time T1 has passed after the detection (Yes in S204), the transfer belt driving means 20 recognizes that the reference mark 19 has reached the set stop position, and stops the rotation of the intermediate transfer belt 15.

  According to the present embodiment, the reference mark 19 is stopped at a desired setting stop position before the start of the next image formation. Since the set stop position is immediately before the detection position of the detection sensor 18, when the next image formation is performed using the reference mark 19, the time required to detect the reference mark 19 can be shortened. It is possible to reduce the time required for

(Embodiment 2)
In the present embodiment, a plurality of detection sensors 18 are provided on the intermediate transfer belt 15. Moreover, the installation location of the detection sensor 18 is made into equal intervals.

  In the first embodiment, for example, when the reference mark 19 happens to be stopped immediately after the detection position of the detection sensor 18 after the previous image formation, it takes about one rotation time for detection. In the present embodiment, in order to shorten the detection time, a plurality of detection sensors are arranged at equal intervals in the apparatus of the first embodiment. When N detection sensors are used, the maximum detection time of the reference mark 19 can be shortened to about “one round rotation time / N”.

  FIG. 8 is a diagram for explaining the processing contents of the present embodiment. As shown in FIG. 8, the two detection sensors 18 a and 18 b are arranged on the intermediate transfer belt 15 at equal intervals. When the stop position of the reference mark 19 before the detection is an area from the detection position of the detection sensor 18b to the detection position of the detection sensor 18a, the reference mark 19 is detected by the detection sensor 18a. The time is the same as that of the apparatus of the first embodiment.

  However, when the stop position of the reference mark 19 before the detection is performed is an area from the detection position of the detection sensor 18a to the detection position of the detection sensor 18b, the reference mark 19 is detected by the detection sensor 18b. It is possible to reduce the half-turn rotation time.

  FIG. 3 is a flowchart showing a processing flow of the present embodiment. In FIG. 3, after the intermediate transfer belt 15 is rotated at the speed V (S301) and detected by one of the detection sensors 18a and 18b (S302), the reference mark 19 is located at a distance X to the detection sensor 18a ( The rotation time T2 for stopping at the set stop position is calculated by the following formula (S303).

T = ((N + 1−n) * L / N−X) / V (2)
L: Length of the intermediate transfer belt 15 V: Rotational speed of the intermediate transfer belt 15 N: Number of detection sensors n: Number of the detection sensor for detecting the reference mark 19 (n = 1 when detected by the detection sensor 18a; When detected by the detection sensor 18b, n = 2)

  The intermediate transfer belt 15 is rotated at the rotation speed V. When the time T2 has passed, it is recognized that the reference mark 19 has reached the set stop position, and the rotation of the intermediate transfer belt 15 is stopped (S305). When the reference mark 19 is detected by the detection sensor n, the calculation result of Expression (2) (movement time from the detection position to the set stop position) is compared with the rotation time calculated by Expression (1) of the first embodiment. Thus, the (n-1) / N rotation time can be reduced.

(Embodiment 3)
In the present embodiment, a plurality of reference marks 19 are provided on the intermediate transfer belt 15. Further, the installation locations of the reference marks 19 are equally spaced.

  In the first embodiment, when the reference mark 19 happens to be stopped immediately after the detection position of the detection sensor 18 after the previous image formation, it takes about one rotation time for detection. Even in the method described in the second embodiment, when the reference mark 19 before the detection is an area from the detection position of the detection sensor 18b in FIG. 8 to the detection position of the detection sensor 18a, the reference mark 19 is the detection sensor. After the detection by 18a, the movement time from the detection position of the detection sensor 18a to the set stop position takes about one rotation time.

  Therefore, in the present embodiment, in order to shorten the movement time after detection, the plurality of reference marks 19a and 19b are arranged at equal intervals in the apparatus of the first embodiment. When N reference marks 19 are used, the detection time of the reference marks 19 can be shortened, and the time from the detection position of the reference marks 19 to the set stop position can be shortened to about “one round rotation time / N”.

  FIG. 10 is a diagram for explaining the contents of the processing of this embodiment. As shown in FIG. 10, two reference marks 19 a and 19 b are arranged on the intermediate transfer belt 15 at equal intervals. After each printing process, along the rotational direction of the intermediate transfer belt 15, the distance X from the reference mark (one of the reference marks 19a and 19b) closest to the detection position of the detection sensor 18 to the set stop position Using the rotation speed V, the rotation time T3 is calculated by the following calculation formula.

T = (L / N−x) / V (3)
L: Length of the intermediate transfer belt 15 V: Rotational speed of the intermediate transfer belt 15 N: Number of reference marks

  For example, when the intermediate transfer belt 15 is rotated at the rotational speed V and the reference mark 18b is detected by the detection sensor 18, the reference mark 18a reaches the set stop position after a time T3 has elapsed from the time of detection. And the rotation of the intermediate transfer belt 15 is stopped. Thus, by providing a plurality of reference marks and arranging them at equal intervals, the rotation time can be shortened. The control flow of the third embodiment is the same as that of FIG. 7 of the first embodiment.

(Embodiment 4)
In the present embodiment, a function is added to Embodiments 1 and 3 that makes it possible to set whether or not to reduce the detection time of the reference mark 19 as shown in Embodiments 1 and 3. It is a thing. FIG. 11 shows a processing flow of the present embodiment. After printing is completed through the control flow of FIG. 4 (S401), whether or not the control unit 21 determines whether or not there is a user operation via the operation unit 113 or the like and performs the detection time reduction according to the first and third embodiments. Is set (S402). When setting (Yes in S402), the reference mark 19 is stopped immediately before the detection sensor 18 (setting stop position). When not set (No in S402), when the printing operation is finished, all the processes are finished. According to this embodiment, the user determines whether or not to reduce the detection time.

(Embodiment 5)
In the present embodiment, a function is added to the second embodiment to make it possible to set whether or not to reduce the detection time of the reference mark 19 as shown in the second embodiment. . FIG. 12 shows a processing flow of the present embodiment. After completion of printing through the control flow of FIG. 4 (S501), the control means 21 determines whether or not a user operation is performed via the operation unit 113 or the like, and sets whether or not to reduce the detection time according to the second embodiment. (S502). When setting (Yes in S502), the reference mark 19 is stopped immediately before the detection sensor 18 (setting stop position). When not set (No in S502), when the printing operation is finished, all the processes are finished. According to this embodiment, the user determines whether or not to reduce the detection time.

1
DESCRIPTION OF SYMBOLS 15 Intermediate transfer belt 16 Transfer belt drive roller 17 Secondary transfer roller 18 Detection sensor 19 Reference mark 20 Transfer belt drive means 21 Control means

JP 2010-281940 A

Claims (5)

An indirect transfer type image forming apparatus,
An intermediate transfer belt;
A reference mark which is an arbitrary image arranged on the intermediate transfer belt;
A detection sensor for reading the reference mark before image formation on the intermediate transfer belt;
Transfer belt driving means for rotating the intermediate transfer belt after image formation so that the reference mark is positioned immediately before the detection position by the detection sensor;
An image forming apparatus comprising: The transfer belt driving unit rotates the intermediate transfer belt at a speed V from the time when the detection sensor detects the reference mark after image formation for a rotation time T1, and the reference mark is detected at a position detected by the detection sensor. The image forming apparatus according to claim 1, wherein the rotation of the intermediate transfer belt is stopped so that the intermediate transfer belt is positioned at a set stop position that is the immediately preceding position.
However, T1 is a value calculated by the following formula.
T1 = ((length L of the intermediate transfer belt) − (distance X from the set stop position to the detection position by the detection sensor)) / (rotational speed V of the intermediate transfer belt)   The image forming apparatus according to claim 1, wherein a plurality of the detection sensors are provided, and the plurality of detection sensors are arranged at equal intervals on the intermediate transfer belt.   4. The image forming apparatus according to claim 1, wherein a plurality of the reference marks are provided, and the plurality of the reference marks are arranged on the intermediate transfer belt at equal intervals.   Control means for setting whether or not to perform an operation of rotating the intermediate transfer belt after image formation so that the reference mark is positioned immediately before the detection position by the detection sensor. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

Images