JP2008281656A - Image forming apparatus and method - Google Patents

Image forming apparatus and method Download PDF

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Publication number
JP2008281656A
JP2008281656A JP2007123893A JP2007123893A JP2008281656A JP 2008281656 A JP2008281656 A JP 2008281656A JP 2007123893 A JP2007123893 A JP 2007123893A JP 2007123893 A JP2007123893 A JP 2007123893A JP 2008281656 A JP2008281656 A JP 2008281656A
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Prior art keywords
sheet
image forming
paper feed
speed
command
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JP2007123893A
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Japanese (ja)
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Maho Oyanagi
麻歩 大柳
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Canon Inc
キヤノン株式会社
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Abstract

The present invention relates to a communication delay generated in an image synchronization signal by matching the timing of transferring a toner image on an image bearing belt with the timing of conveying a sheet without being affected by the length of the conveying path. An image forming apparatus capable of reducing the above is provided.
An image forming apparatus receives an image forming signal indicating the start of toner image formation and a paper feed start command indicating a command to start feeding on a conveyance path from an image forming unit. And a paper feed start command are activated, the control means for controlling the paper transport speed is provided.
[Selection] Figure 3

Description

  The present invention relates to an image forming apparatus having sheet feeding control means.

  2. Description of the Related Art Image forming apparatuses that transfer a toner image onto a sheet-like transfer paper are widely used. Such an image forming apparatus is often used with an optional paper feeding unit connected thereto. In recent years, optional units of image forming apparatuses have become more sophisticated, and there is an increasing demand for improved control functions by the engine unit. However, in the case of improving the function of the engine unit, it is important to achieve a balance with cost reduction, and various technologies have been developed for such problems.

  In the following Patent Document 1, a printing apparatus that can use various option units without increasing the cost of an engine controller is disclosed. According to this printing apparatus, it is described that the conveyance of the paper is efficiently controlled even when the optional unit is connected to the printing apparatus.

  In general, in the image forming apparatus, there is a problem that variations occur in the time during which the toner image is conveyed to the transfer position where the toner image is transferred to the paper after the paper feeding is started. Such variations are mainly caused by variations in the sheet position in the sheet conveying means, the sheet pickup operation for feeding the sheet onto the conveyance path, or the sheet pickup operation such as slip. In addition, it is caused by variations in the sheet conveyance path length due to the sheet quality. The variation in the time during which the toner image is transported to the position where the toner image is transferred to the paper after the paper feeding is started as described above becomes a factor that deteriorates the accuracy of the transfer position of the toner image on the paper.

  FIG. 13 is a diagram illustrating a configuration of a conventional image forming apparatus. As shown in FIG. 13, the image forming apparatus includes an image forming unit 1301 and an option unit 1302. Conventionally, the option unit 1302 receives an image synchronization signal (not shown) from the image forming unit 1301 by serial communication or the like. Further, the option unit 1302 is instructed to start feeding by a command from the image forming unit 1301, drives the pickup roller 1303, and as a result, conveyance of the sheet from the tray 1304 is started.

  The sheet is conveyed to the image forming unit 1301 via the feed retard roller 1305 and the conveyance roller 1306. The image drawn on the image carrier belt 1311 by the toner cartridge 1307 (Y: yellow), 1308 (M: magenta), 1309 (C: cyan), 1310 (K: black) is the secondary transfer position of the image forming unit 1301. The image is transferred to a sheet conveyed to 1312. Thereafter, the transferred paper is discharged from the paper discharge unit 1313.

  Conventionally, when the sheet is likely to reach the secondary transfer position 1312 before the image drawn on the image carrier belt 1311, the sheet being conveyed at the sheet detection position 1315 near the registration roller 1314 of the image forming unit 1301. The tip is detected and the conveyance is temporarily stopped. As a result, adjustment of the timing at which the paper reaches the secondary transfer position 1312 is realized, and the above-described variation problem is solved.

  By the way, in recent years, an image forming apparatus capable of connecting a plurality of option units for expanding the sheet feeding capacity in multiple stages has been widely used. In such a printer, the conveyance time from the paper feeding position of the optional unit to the transfer position of the toner image is detected after the notification of the image synchronization signal is received, and the conveyance is started, and the paper near the registration roller of the image forming unit is detected. It may be longer than the time to reach the position. In such a case, there may be a case where a deviation occurs in the timing of transfer to the paper even by the conventional method of temporarily stopping the conveyance at the paper detection position near the registration roller of the image forming unit. In order to temporarily stop the conveyance when conveying a large number of sheets, it is necessary to perform synchronous control between the CPU in the image forming unit and the CPU in the option unit, which increases the scale of the circuit configuration and makes it complicated. It will become.

  Further, in recent years, image forming apparatuses that have increased paper feeding capacity and increased printing speed (throughput) have been widely used. In such an image forming apparatus, for example, a high throughput is realized when the paper conveyance speed is the same by controlling the interval of the conveyed paper to be precise.

As already described, in the conventional image forming apparatus, the option unit receives the image synchronization signal from the image forming unit. Therefore, there may be a case where a variation in communication delay occurs in the image synchronization signal. In such a case, there may be a case where the control of the interval between papers that requires high precision is affected, and the timing of transfer onto the paper is shifted.
JP 08-286567 A (paragraph [0052])

  Therefore, in view of the above points, the present invention matches the timing of transferring the toner image on the image bearing belt with the timing of transporting the paper without being affected by the length of the transport path, and the image synchronization signal. An image forming apparatus capable of reducing a communication delay occurring in the image forming apparatus is provided.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a cassette for storing sheets, a plurality of paper feed options having a conveyance path and rollers for conveying the sheets, and an image forming unit for forming a toner image. An image forming apparatus that transports a sheet stored in a cassette to a transfer position for transferring a formed toner image to the sheet via a transport path, wherein the image forming unit forms a toner image An image forming signal indicating that the image forming has started and a sheet feeding start command indicating an instruction to start feeding from the cassette to the conveyance path are input from the image forming unit, and the image forming signal and the sheet feeding start command are When activated, the speed at which the sheet is transported in the transport path is calculated according to the distance from the position of the sheet being transported to the transfer position, and the drive unit that drives the roller is controlled based on the speed. And control means, at the transfer position, characterized in that it is possible to synchronize the conveyance of the transfer and sheet the toner image.

  According to the present invention, the timing at which the toner image on the image bearing belt is transferred and the timing at which the paper is conveyed are matched without being affected by the length of the conveyance path, thereby reducing the communication delay generated in the image synchronization signal. Can be reduced.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 1 is a diagram illustrating a configuration around a control CPU according to the image forming apparatus according to the first embodiment. The image forming apparatus shown in FIG. 1 includes an image forming unit 1 and an option unit 2. Further, the option unit 2 includes paper feed options 3, 4, and 5 including a cassette in which paper to be fed is stored. Further, the image forming unit 1 and the option unit 2 include respective control CPUs 10 and 20. The control CPU 20 drives a conveyance motor included in the paper feed options 3, 4, and 5 via the drive unit 21. Here, four or more paper feed options may be included.

  As shown in FIG. 1, the control CPU 10 and the control CPU 20 communicate with each other through an interface signal line. In this embodiment, the interface signal includes a clock signal, a command signal, and a status signal. For example, the clock signal is used when the control CPU 10 and the control CPU 20 are synchronized, and the command signal is used when a paper feed start command or the like is transmitted to the control CPU 20. The status signal is used, for example, when information indicating the status of the paper feed options 3, 4, and 5 is transmitted to the image forming unit 1. As shown in FIG. 1, the control CPU 20 has terminals for inputting a clock signal, a command signal, and a status signal for each of the paper feed options 3, 4, and 5.

  In the present embodiment, the image synchronization signal is input to the control CPU 20 as an independent signal line different from the interface signal. The image synchronization signal in the present embodiment is, for example, an electrical hardware signal, and the control CPU 20 recognizes that the image forming unit 1 has started drawing on the image bearing belt, for example, based on the voltage level. Therefore, unlike the interface signal, bi-directional communication is not performed, and unidirectional communication notified from the control CPU 10 to the control CPU 20 is performed. In the following, the image synchronization signal is also referred to as an “image formation signal” as a signal indicating the start of image formation.

  In the present embodiment, since the image synchronization signal is configured as a signal line as shown in FIG. 1, it is possible to suppress a communication delay that may occur during bus communication or bidirectional communication.

  FIG. 2 is a diagram illustrating a configuration of a portion related to the paper transport mechanism in the image forming apparatus according to the present embodiment. In FIG. 2, the control CPUs 10 and 20 are not shown. The image forming unit 1 includes a toner cartridge that transfers a toner image onto a conveyed sheet (sheet) and a secondary transfer roller. In FIG. 2, as the toner cartridge 29, a developing unit having toners of yellow (Y), magenta (M), cyan (C), and black (K) from the left is shown. Hereinafter, in the description of this embodiment, the secondary transfer roller is assumed to be the secondary transfer position 27. A registration roller 25 and a registration sensor 26 are configured as a mechanism for transporting the sheet to the secondary transfer position 27.

  As shown in FIG. 2, the image forming unit 1 includes a cassette 22 in which paper is stored, and paper is output from the cassette 22 as the pickup roller 23 and the feed retard roller 24 rotate. In FIG. 2, paper feed options 3 and 4 are configured, and include a cassette 30, a pickup roller 31, a feed retard roller 32, and a cassette 40, a pickup roller 41, and a feed retard roller 42, respectively. The paper feed options 3 and 4 are connected by a transport path 6, and transport rollers 33 and 43 for transporting the transport path 6 are configured. In the vicinity of the transport rollers 33 and 43, transport path sensors 34 and 44 for detecting the presence or absence of paper are provided.

  Hereinafter, the sheet transport operation will be described with reference to FIG. 1 together with the configuration of the image forming apparatus. However, in the following description, it is assumed that paper is fed from the paper feed option 4 to the image forming unit 1.

  The control CPU 10 transmits a motor rotation command to the control CPU 20 by a command signal. When receiving the motor rotation command, the control CPU 20 drives the transport rollers 33 and 43 via the drive unit 21 shown in FIG. The transport rollers 33 and 43 are driven in common by a transport motor included in the drive unit 21. The drive unit 21 will be described later.

  When the control CPU 10 transmits a motor rotation command to the control CPU 20, the control CPU 10 transmits a paper feed start command to the control CPU 20 by a command signal. When receiving a paper feed start command from the control CPU 10 by a command signal, the control CPU 20 drives the pickup roller 41 and the feed retard roller 42 to output paper from the cassette 40 and starts a paper feeding operation. When the paper feeding operation is started, the paper is transported to the transport path sensor 44 by the feed retard roller 42. When the sheet is conveyed to the conveyance path sensor 44, the pickup roller 41 and the feed retard roller 42 are stopped. On the other hand, the sheet is transported along the transport path 6 by transport rollers 33 and 43. Here, since the pickup roller and the feed retard roller are used when outputting paper from the cassette, they operate individually in the respective paper feed options 3 and 4 unlike the above-described transport rollers 33 and 43.

  In addition, the paper feed option 4 recognizes that the image synchronization signal is activated within a predetermined time from the paper feed start command by the electric hardware signal. When the image synchronization signal is transmitted to the control CPU 20, transfer of the toner image from the toner cartridge 29 to the image carrier belt 28 is started. The time for the toner image drawn on the image carrier belt 28 to reach the secondary transfer position 27 can be known as a value of the engine performance of the image forming apparatus. In the section from the registration sensor 26 to the secondary transfer position 27, conventionally, the control CPU 10 controls the transport speed of the sheet transported in the section or sets the speed to be constant between the toner image and the sheet. Various methods such as control are realized. Therefore, in this embodiment, the distance from the registration sensor 26 to the secondary transfer position 27 and the conveyance time are set to known values. The known values as described above may be stored in a memory or the like configured around the control CPU 10 or 20.

  In the present embodiment, by determining the transport speed in the section from the paper feed option to the registration sensor 26 to an appropriate speed, a deviation in the timing at which the paper reaches the secondary transfer position 27 due to the length of the transport path 6 is achieved. It is preventing. Hereinafter, the operation of this embodiment will be described. FIG. 3 is a timing chart showing waveforms of signals for explaining the calculation of the conveyance speed in the first embodiment. In FIG. 3, the level change of the image synchronization signal, the timing at which a paper feed start command is transmitted from the control CPU 10 to the control CPU 20, the change in detection signals of the conveyance path sensor 34 and the registration sensor 26, and the paper at the secondary transfer position 27. The change of the detection signal of the presence or absence of is shown. In FIG. 2, the secondary transfer position 27 is illustrated as a secondary transfer roller. However, a sensor is formed in the vicinity, and when the paper reaches the secondary transfer position 27, a signal is output as shown in FIG. It may be possible to detect the change. In FIG. 3, the conveyance path sensor 34, the registration sensor 26, and the secondary transfer position 27 are activated to a high level when a sheet is detected.

  As shown in FIG. 3, the time from when the image synchronization signal is activated to the low level until the sheet reaches the registration sensor 26 is defined as T1. Further, t is the time when the control CPU 10 transports from the registration sensor 26 to the secondary transfer position 27 at the normal transport speed. Further, T2 is a time during which the image synchronization signal is activated and the sheet must reach the secondary transfer position 27. That is, T2 corresponds to the time until the image synchronization signal is activated and the toner image reaches the secondary transfer position 27 by the movement of the image carrier belt 28.

  The time T1 in the section in which the conveyance speed in the present embodiment is controlled, that is, the section until the image synchronization signal is activated and the sheet reaches the registration sensor 26 is obtained by Expression (1).

T1 = T2-t (1)
Further, the transport distance L by which the image synchronization signal is activated and the sheet is transported to the registration sensor 26 is obtained by Expression (2).

L = a + b (2)
Here, a is the distance from the paper position to the conveyance path sensor 34 when the image synchronization signal is activated, and b is the distance from the conveyance path sensor 34 to the registration sensor 26. As described above, the conveyance speed v1 from the sheet position at the time when the image synchronization signal is activated to the registration sensor 26 is obtained by the equation (3).

v1 = L / T1 (3)
Here, the operation of the image forming apparatus will be described with reference to FIG. First, when a motor rotation command is transmitted from the control CPU 10 to the control CPU 20, the transport rollers 33 and 43 are rotated. Subsequently, when a paper feed start command is transmitted to the control CPU 20, the paper is output from the cassette 40, and the paper is transported along the transport path 6 by the rotating transport rollers.

  Next, the control CPU 10 activates the image synchronization signal and starts to move the image carrier belt 28. At that time, time T2 is determined, and time T1 is determined according to equation (1) using known time t. Here, even while the image synchronization signal is activated, the sheet is being conveyed on the conveyance path 6.

  In the present embodiment, the position of the sheet being conveyed at the time when the image synchronization signal is activated is recognized by the conveyance path sensor configured in at least one of the sheet feeding options. In FIG. 3, it is assumed that after the image synchronization signal is activated, the sheet passes through the conveyance roller 33 and reaches the conveyance path sensor 34. In the section a shown in FIG. 3, the sheet is conveyed at a speed (hereinafter referred to as a reference speed) according to a motor rotation command. Furthermore, since the control CPU 20 can recognize the time from when the image synchronization signal is activated until the conveyance path sensor 34 is activated, the distance a is obtained. When the distance a is obtained, the distance L is obtained according to the equation (2). As a result, the conveyance speed v1 is obtained according to the equation (3).

  As described above, when the conveyance speed v1 is obtained, the control CPU 20 controls the rotation speed of the conveyance roller to change the conveyance speed v1 from the reference speed.

  FIG. 4 is a diagram illustrating functional blocks of a drive unit that drives the conveyance roller in the present embodiment. As shown in FIG. 4, the drive unit 21 is configured subsequent to the control CPU 20, and the drive unit 21 includes a speed switching unit 210, a drive circuit 211, and a transport motor 212. Further, as already described, the transport motor 212 drives the transport rollers 33 and 43. The control CPU 20 can input the detection results of the conveyance path sensors 34 and 44 and recognize the position of the sheet on the conveyance path 6. In addition, the control CPU 20 inputs an image synchronization signal and a paper feed start signal. In addition, a memory such as a RAM (not shown) is configured around the control CPU 20. Values that can be acquired as known values in such a memory, such as the time that the toner image formation in the image forming unit 1 is started and supplied to the secondary transfer position, the distance from each conveyance path sensor or each cassette to the registration sensor, etc. May be stored.

  When the transport speed v1 is obtained by the control CPU 20, the control CPU 20 further obtains a relative ratio between the transport speed v1 and the reference speed v.

  In the speed switching means 210, it is determined whether the obtained relative ratio is larger or smaller than one time. Here, when it is determined that the relative ratio is greater than one time, the drive circuit 211 is controlled so as to accelerate the rotation of the transport motor 212. On the other hand, when it is determined that the relative ratio is smaller than 1, the drive circuit 211 is controlled so as to decelerate the rotation of the transport motor 212. The transport motor 212 rotates according to the drive circuit 211 and drives the transport rollers 33 and 43. In the present embodiment, as described above, the sheet conveyance speed in the section up to the registration sensor 26 on the conveyance path 6 is controlled.

  The case where the speed switching unit 210 determines that the relative ratio is large is, for example, a case where the sheet is transported at the reference speed v but is not transported smoothly at a certain position on the transport path 6. . In such a case, it can be said that the position of the sheet at the time when the image synchronization signal is activated is lower than that when the sheet is smoothly conveyed. That is, it can be said that the distance L shown in FIG. 3 is longer than the case where the distance L is smoothly conveyed. In such a case, the control CPU 20 accelerates the transport roller via the drive unit 21.

  From the registration sensor 26 to the secondary transfer position 27, the control CPU 10 synchronously controls the toner image on the image carrier belt 28 and the paper as in the conventional case.

  FIG. 5 is a flowchart illustrating a procedure of sheet feeding control of the option unit in the image forming apparatus according to the present embodiment. First, in step S500, the control CPU 20 receives a motor rotation command from the control CPU 10, and in step S501, the driving unit 21 starts rotation of the transport rollers 33 and 43. In step S502, a paper feed start command is received from the control CPU 10, and in step S503, the pickup roller 41 is driven. In step S504, the feed retard roller 42 is driven.

  Next, in step S505, it is determined whether or not a sheet is detected by the conveyance path sensor 44 of the sheet feeding option 4. Here, step S505 is repeated until it is determined that it has been detected. If it is determined that the sheet is detected, the process proceeds to step S506, and the pickup roller 41 and the feed retard roller 42 are stopped. In step S507, the control CPU 20 recognizes that the image synchronization signal has been activated, and recognizes which paper feed option is configured by the conveyance path sensor that has detected the paper. Next, in step S508, the conveyance speed v1 in the section to the registration sensor 26 on the conveyance path 6 is calculated. Based on the calculation result, in step S509, the sheet is conveyed while being accelerated or decelerated. In step S510, it is determined whether or not a sheet is detected by the registration sensor 26. Here, step S510 is repeated until it is determined that it has been detected. If it is determined that the sheet has been detected, the process proceeds to step S511, where the control of the conveyance speed is terminated, and the sheet is conveyed at the reference speed. In this flowchart, the registration roller 25 is rotating at the reference speed. In step S512, it is determined whether the trailing edge of the sheet has passed through the conveyance path sensor 34 of the uppermost sheet feeding option 3. Here, step S505 is repeated until it is determined that it has passed. If it is determined that it has passed, the process proceeds to step S513, where the option unit 2 stops the motor and the like, and ends this flowchart.

  FIG. 6 is a flowchart illustrating a procedure of paper feed control of the image forming unit 1 in the image forming apparatus according to the present embodiment. First, in step S600, the control CPU 10 receives a print reservation command through a user interface (not shown), and transmits a motor rotation command to the control CPU 20 in step S601. Next, in step S602, when the control CPU 10 receives a print execution command via a user interface (not shown), in step S603, the control CPU 10 activates the image synchronization signal.

  Next, in step S604, an image is formed on the image carrier belt 28. In step S605, it is determined whether or not the leading edge of the paper has reached the registration sensor 26. Here, step 605 is repeated until it is determined that it has been reached. If it is determined that it has reached, in step S606, synchronization control is performed from the registration sensor 26 to the secondary transfer position 27, and the sheet is conveyed to the secondary transfer position 27. Here, the control CPU 10 may control the speed from the registration sensor 26 to the secondary transfer position 27 to perform synchronous control between the toner image and the paper. In step S607, the toner image is transferred to the sheet at the secondary transfer position 27. In step S608, the sheet is discharged, and this flowchart is ended.

  As described above, in the present embodiment, a paper feed start command is transmitted to the option unit 2 before the image synchronization signal is activated, and the option unit 2 performs conveyance at the time when the image synchronization signal is activated. The conveyance speed on the path 6 is controlled. As a result, even in an image forming apparatus configured with a plurality of paper feed options, it is possible to perform appropriate speed control in accordance with the conveyance path length. Further, in the present embodiment, the sheet continues to be conveyed and does not stop until it passes through the registration sensor 26 and reaches the secondary transfer position 27 after the sheet feeding operation is started. Therefore, for example, it is possible to reduce the configuration of the synchronous control between the control CPU of the image forming unit 1 and the control CPU of the option unit 2 that is required when a plurality of sheets are continuously transmitted. In this embodiment, since the image synchronization signal is transmitted from the control CPU 10 to the control CPU 20 as an electrical hardware signal independent of other interface signals, occurrence of variations in communication delay can be suppressed. it can.

  Next, the paper feed control of the option part in the second embodiment will be described.

  FIG. 7 is a timing chart showing waveforms of signals for explaining the calculation of the conveyance speed in the second embodiment. As shown in FIG. 7, the time from when the paper feed start command is transmitted from the control CPU 10 until the image synchronization signal is activated is determined as the reference time T.

  That is, in the present embodiment, when the image synchronization signal is not activated within the time of the reference time T, the transport operation is performed when the sheet reaches the transport path sensor configured as the uppermost sheet feed option. To pause. Thereafter, when the control CPU 20 recognizes that the image synchronization signal has been activated, the transport operation is resumed.

  In FIG. 7, when a paper feed start command is transmitted from the control CPU 10 to the control CPU 20, the paper is output from the cassette 40 and is transported through the transport path 6. The control CPU 20 measures the reference time T by using a timer or the like after receiving the paper feed start command. If the image synchronization signal is not activated even after the reference time T has elapsed, the transport rollers 33 and 43 are stopped when the paper reaches the transport path sensor 34. Here, when the image synchronization signal is activated within the reference time T, the description is the same as that in FIG.

  When the image synchronization signal is activated while the sheet is stopped in the conveyance path sensor 34, the control CPU 20 recognizes the time T2 during which the sheet is conveyed to the secondary transfer position 27, and further, the sheet is detected by the registration sensor. The time T1 transported up to 26 is recognized. The conveyance speed v2 is obtained from the distance L shown in FIG. 7 and the time T1. Here, the distance L is a distance from the conveyance path sensor 34 to the registration sensor 26. The time t is the same as described in FIG. The conveyance of the sheet is resumed at the conveyance speed v2 obtained as described above. Here, when the conveyance of the sheet is resumed, the timing at which the conveyance of the sheet is resumed may be controlled based on the reference speed and the distance L instead of controlling the speed.

  FIG. 8 is a flowchart showing a procedure of sheet feeding control of the option unit in the second embodiment.

  Steps S800 to S806 shown in FIG. 8 are the same as the descriptions of steps S500 to S506 shown in FIG. Further, Steps S808 to S813 shown in FIG. 8 are the same as the description from Steps S508 to S513 shown in FIG. In the present embodiment, in step S807, the reference time T is measured after the control CPU 20 receives the paper feed start command. If the image synchronization signal is not activated within the reference time T, the processing after step S814 is performed.

  In step S815, it is determined whether or not the transport path sensor in the uppermost paper feed option has detected the leading edge of the paper. Here, step S815 is repeated until it is determined that it has been detected. If it is determined that it has been detected, the control CPU 20 temporarily stops the transport rollers 33 and 43 via the drive unit 21 in step S816.

  Next, in step S817, it is determined whether the image synchronization signal has been activated. Here, step S817 is repeated until it is determined that the activation has been made. If it is determined that it has been activated, the transport speed v2 is obtained from the distance L and time T1 shown in FIG. 7 in step S818, and transport is resumed at the transport speed v2 in step S819. After transport is resumed, the process proceeds to step S812, and it is determined whether or not it has been detected that the trailing edge of the paper has passed through the transport path sensor of the uppermost paper feed option, as in step S512 shown in FIG. The If it is detected that it has passed, the motor and the like are stopped in step S813, and this flowchart is terminated.

  The paper feed control process in the image forming unit 1 is the same as the description in FIG.

  As described above, in this embodiment, when the image synchronization signal is not activated even after the start of paper feeding and the reference time elapses, the paper that is being transported is transported as the transport path sensor of the uppermost paper feed option. Pause at the position of. As a result, when the image synchronization signal is not activated, the sheet can be prevented from being conveyed to the secondary transfer position.

  Next, the paper feed control of the option unit 2 in the third embodiment will be described.

  FIG. 9 is a timing chart showing waveforms of signals for explaining the calculation of the conveyance speed in the third embodiment.

  As shown in FIG. 9, the time until the image synchronization signal is activated and the sheet reaches the secondary transfer position 27 is T3, the image synchronization signal is activated, and the control CPU 20 receives the paper feed start command. Let time be T. Further, the control CPU 20 receives a paper feed start command, and the distance that the paper is transported to the secondary transfer position 27 is L2. Further, t is the time when the control CPU 10 transports from the registration sensor 26 to the secondary transfer position 27 at the normal transport speed. Further, the distance from the registration sensor 26 to the secondary transfer position 27 is S.

  Accordingly, the distance L from when the control CPU 20 receives the paper feed start command until the paper reaches the registration sensor 26 is obtained by the equation (4).

L = L2-s (4)
Further, the time T2 for transporting the necessary paper in the section from when the control CPU 20 receives the paper feed start command until the paper reaches the registration sensor 26 is obtained by Expression (5).

T2 = T3- (T + t) (5)
Accordingly, the conveyance speed v3 in the section from when the control CPU 20 receives the paper feed start command until the paper reaches the registration sensor 26 is obtained by the equation (6).

v3 = L / T2 (6)
A relative ratio to the normal transport speed is obtained from the obtained transport speed v3, and paper acceleration / deceleration control is performed based on the relative ratio.

  Here, the operation of the image forming apparatus will be described with reference to FIG.

  As shown in FIG. 9, first, when a motor rotation command is transmitted from the control CPU 10 to the control CPU 20, the transport rollers 33 and 43 are rotated. Next, the control CPU 10 activates the image synchronization signal, and the transfer of the toner image from the toner cartridge 29 to the image carrier belt 28 is started. Subsequently, when a paper feed start command is transmitted to the control CPU 20, the paper is output from the cassette 40, and the paper is transported along the transport path 6 by the rotating transport rollers.

Here, when the control CPU 20 receives a paper feed start command, a time T shown in FIG. 9 is determined. Further, since the distance from the cassette 40 to the secondary transfer position 27 depends on the image forming apparatus, it is a known value in the present embodiment. Here, the distance L from the cassette 40 to the registration sensor 26 may be directly used as a known value without using the distance S shown in FIG.
The conveyance speed v3 is calculated based on the value obtained as described above. When the conveyance speed v3 is obtained, the control CPU 20 controls the rotation speed of the conveyance roller so as to set the conveyance speed v3 from the reference speed.

  The functional blocks for controlling the driving of the conveyance rollers in this embodiment are the same as those described in FIG.

  FIG. 10 is a flowchart illustrating a procedure of sheet feeding control of the option unit in the present embodiment. First, in step S1000, the control CPU 20 receives a motor rotation command from the control CPU 10, and in step S1001, drives the carry motor to start rotation of the carry roller. In step S1002, the image synchronization signal is activated, and in step S1003, the control CPU 20 receives a paper feed start command. Next, in step S1004, the pickup roller 41 is driven, and in step S1005, the feed retard roller 42 is driven.

  In step S1006, it is determined whether the paper is detected by the conveyance path sensor 44. Here, step S1006 is repeated until it is determined that it has been detected. If it is determined that it has been detected, the pickup roller 41 and the feed retard roller 42 are stopped in step S1007. In step S1008, the time until the sheet reaches the registration sensor 26 is calculated. Based on the calculation result, in step S1009, the conveyance speed is accelerated or decelerated, and the sheet is conveyed. If the information indicating which paper feed option is specified is included in the paper feed start command, step S1008 and step S1009 are executed after step S1003, step S1004, and step S1005. Also good.

  Next, in step S1010, the registration sensor 26 determines whether a sheet is detected. Here, step S1010 is repeated until it is determined that it has been detected. If it is determined that the sheet is detected, the process advances to step S1011 to end the control of the conveyance speed and convey the sheet at the reference speed. In this flowchart, the registration roller 25 is rotating at the reference speed. In step S1012, it is determined whether the trailing edge of the sheet has passed through the conveyance path sensor 34 of the uppermost sheet feeding option 3. Here, step S1012 is repeated until it is determined that it has passed. If it is determined that it has passed, the process proceeds to step S1013, where the option unit 2 stops the motor and the like, and ends this flowchart. The paper feed control process in the image forming unit 1 is the same as the description in FIG.

  As described above, in this embodiment, even when the control CPU 20 receives a paper feed start command after the time when the image synchronization signal is activated, the paper feed specified by the paper feed start command is performed. An appropriate speed corresponding to the distance from the paper option to the registration sensor 26 is calculated. Here, for example, the control CPU 20 receives a paper feed start command, the paper stored in the cassette is fed to the transport path 6, and the transported paper passes through the feed retard roller. To the registration sensor 26. Further, in the present embodiment, the sheet continues to be conveyed and does not stop until it passes through the registration sensor 26 and reaches the secondary transfer position 27 after the sheet feeding operation is started. Therefore, for example, it is possible to reduce the configuration of the synchronous control between the control CPU of the image forming unit 1 and the control CPU of the option unit 2 that is required when a plurality of sheets are continuously transmitted. In this embodiment, since the image synchronization signal is transmitted from the control CPU 10 to the control CPU 20 as an electrical hardware signal independent of other interface signals, occurrence of variations in communication delay can be suppressed. it can.

  Next, the paper feed control of the optional part in the fourth embodiment will be described. In the first embodiment already described, when the image synchronization signal is activated and the current position of the sheet is recognized by the conveyance path sensor, the conveyance speed to the registration sensor 26 is obtained. Further, the sheet is transported to the registration sensor 26 according to the determined transport speed.

  In FIG. 2, the paper feed option is two stages, but for example, the more the number of stages is four, five, etc., the higher the possibility that the conveyance speed does not become a constant value on the conveyance path 6. For example, there may be a case where the conveyance speed temporarily decreases in a part of the conveyance path 6 due to the quality of the sheet. Therefore, in this embodiment, when the paper reaches the transport path sensor of the uppermost paper feed option, the transport speed to the registration sensor 26 is calculated again. As a result, it is possible to compensate for the fluctuation in the conveyance speed that has occurred on the conveyance path 6.

  FIG. 11 is a timing chart showing waveforms of signals for explaining the calculation of the conveyance speed in the fourth embodiment.

  As shown in FIG. 11, the time from when the image synchronization signal is activated until the sheet reaches the registration sensor 26 is T1, and from when the image synchronization signal is activated until the sheet reaches the conveyance path sensor 34. Let time be T2. Further, the distance from the conveyance path sensor 44 to the registration sensor 26 is L1, and the distance from the activation of the image synchronization signal to the conveyance path sensor 44 is L2. Further, the distance from the conveyance path sensor 34 to the registration sensor 26 is L3. Here, the conveyance path sensor 44 is a conveyance path sensor in which a sheet is first detected after the sheet feeding start command is received by the control CPU 20 and the image synchronization signal is activated. The conveyance path sensor 34 is a conveyance path sensor in the uppermost sheet feeding option.

  The distance L2 shown in FIG. 11 is obtained in the same manner as the distance a shown in FIG. That is, in the section of distance L2 shown in FIG. 11, the sheet is conveyed at the reference speed based on the motor rotation command. Furthermore, since the control CPU 20 can recognize the time from when the image synchronization signal is activated until the conveyance path sensor 44 is activated, the distance L2 is obtained. Accordingly, the conveyance speed v4 is obtained from the distance (L1 + L2) from the time when the image synchronization signal is activated to the registration sensor 26 and the time T1. The time T1 is obtained in the same manner as T1 shown in FIG.

  Next, when the sheet is conveyed to the conveyance path sensor 34, the conveyance speed v5 is calculated again. The conveyance speed v5 is obtained from the time (T1−T2) obtained from the difference between the time T1 and the time T2 and the distance L3. When the conveyance speed v5 is obtained, the sheet is conveyed to the registration sensor 26, and the subsequent operation is the same as described in the first to third embodiments.

  As described above, in the present embodiment, the conveyance is performed at the time point detected by the conveyance path sensor immediately after the image synchronization signal is activated and the time point detected by the conveyance path sensor of the uppermost sheet feeding option. Speed calculation is performed. Therefore, even if the conveyance speed v4 does not become constant on the conveyance path 6 due to a specific cause, the calculation is performed again by the conveyance path sensor of the uppermost paper feed option, and this is caused by the cause. It is possible to compensate for deviations in the arrival timing of the paper to be printed.

  The control of the sheet conveyance speed is the same as that described in FIG.

  FIG. 12 is a flowchart illustrating a procedure of sheet feeding control of the option unit according to the fourth embodiment. First, in step S1200, the control CPU 20 receives a motor rotation command, and in step S1201, starts the rotation of the transport roller. When the control CPU 20 receives a paper feed start command in step S1202, the pickup roller 41 is driven in step S1203, and the feed retard roller 42 is driven in step S1204. In step S1205, the image synchronization signal is activated. In step S1206, when the conveyance path sensor of the paper feed option including the cassette for which paper feeding has been started detects paper, the pickup roller 41 and the feed retard roller 42 are stopped in step S1207.

  Next, in step S1208, the conveyance speed v4 described in FIG. 11 is calculated. In step S1209, the paper is accelerated or decelerated depending on the calculation result. In step S1210, when the transport path sensor of the uppermost paper feed option detects a sheet, the transport speed v5 described in FIG. 11 is calculated in step S1211. In step S1212, acceleration or deceleration paper conveyance is performed based on the calculation result.

  In step S1213, the registration sensor 26 determines whether a sheet is detected. If it is determined that the sheet is detected, the process advances to step S1214 to end the control of the conveyance speed and convey the sheet at the reference speed. In this flowchart, the registration roller 25 is rotating at the reference speed. In step S1215, it is determined whether the trailing edge of the sheet has passed through the conveyance path sensor 34 of the uppermost sheet feeding option 3. Here, step S1215 is repeated until it is determined that it has passed. If it is determined that it has passed, the process advances to step S1216, and the option unit 2 stops the motor and the like, and ends this flowchart.

  In addition, according to the present invention, an operating system (OS) operating on a computer performs part or all of actual processing based on an instruction of a program code, and the functions of the above-described embodiments are realized by the processing. This is also included. Furthermore, the present invention is also applied to the case where the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. In that case, the CPU of the function expansion card or function expansion unit performs part or all of the actual processing based on the instruction of the written program code, and the functions of the above-described embodiments are realized by the processing. Is done.

FIG. 3 is a diagram illustrating a configuration around a control CPU according to the image forming apparatus according to the first embodiment. 2 is a diagram illustrating a configuration of a portion related to a paper transport mechanism in the image forming apparatus according to the present embodiment. It is a timing chart which shows the waveform of each signal explaining calculation of the conveyance speed in a 1st embodiment. It is a figure which shows the functional block of the drive part which drives the conveyance roller in this embodiment. 6 is a flowchart illustrating a procedure of sheet feeding control of an option unit according to the first embodiment. 6 is a flowchart illustrating a procedure of paper feed control of the image forming unit. It is a timing chart which shows the waveform of each signal explaining calculation of conveyance speed in a 2nd embodiment. 10 is a flowchart illustrating a procedure of sheet feeding control of an option unit in the second embodiment. It is a timing chart which shows the waveform of each signal explaining calculation of conveyance speed in a 3rd embodiment. 10 is a flowchart illustrating a procedure of sheet feeding control of an option unit in the third embodiment. It is a timing chart which shows the waveform of each signal explaining calculation of conveyance speed in a 4th embodiment. 14 is a flowchart illustrating a procedure of sheet feeding control of an option unit in the fourth embodiment. It is a figure which shows the structure of the conventional image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1301 Image formation part 2,1302 Option part 3,4,5 Paper feed option 6 Conveyance path 10,20 Control CPU
21 Drive unit 22, 30, 40, 1304 Cassette 23, 31, 41, 1303 Pickup roller 24, 32, 42, 1305 Feed retard roller 25, 1314 Registration roller 26, 1315 Registration sensor 27, 1312 Secondary transfer position 28, 1311 Image bearing Belt 29, 1307, 1308, 1309, 1310 Toner cartridge 33, 43, 1306 Conveyance roller 34, 44 Conveyance path sensor 210 Speed switching means 211 Drive circuit 212 Conveyance motor

Claims (6)

  1. A cassette for storing sheets; a plurality of sheet feeding options having a transport path and rollers for transporting the sheets; and an image forming unit for forming a toner image, wherein the sheets stored in the cassette are transferred to the transport path. An image forming apparatus that conveys the formed toner image to a transfer position for transferring to a sheet,
    An image forming signal indicating that the image forming unit has started forming a toner image and a paper feed start command indicating a command to start feeding from the cassette to the transport path are input from the image forming unit, Further, when the image forming signal and the paper feed start command are activated, the speed at which the sheet is conveyed in the conveyance path is calculated according to the distance from the position of the sheet being conveyed to the transfer position, An image forming apparatus including: a control unit configured to control a driving unit that drives the roller based on the speed, wherein the speed is a speed at which the transfer of the toner image and the conveyance of the sheet are synchronized at the transfer position.
  2. Constructed in at least one of the plurality of paper feed options, a transport path sensor for detecting the presence or absence of a sheet in the transport path, and in the image forming unit, and a sheet at the transfer position A registration sensor for detecting the presence or absence of a sheet in the registration roller for conveying,
    The control means is
    Recognizing that the image forming signal is activated after the paper feed start command is activated,
    Recognizing the position of the sheet in the conveyance path by the conveyance path sensor,
    Calculating the speed from the distance and time from the recognized sheet position to the registration sensor;
    The image forming apparatus according to claim 1.
  3. Constructed in at least one of the plurality of paper feed options, a transport path sensor for detecting the presence or absence of a sheet in the transport path, and in the image forming unit, and a sheet at the transfer position A registration sensor for detecting the presence or absence of a sheet in the registration roller for conveying,
    The control means is
    Recognizing that a reference time has elapsed since the paper feed start command was activated,
    When the sheet reaches the conveyance path sensor configured in the sheet feeding option closest to the image forming unit among the plurality of sheet feeding options, the roller is stopped,
    Recognizing the activated image forming signal, the speed is calculated from the distance and time from the conveyance path sensor to the registration sensor,
    The image forming apparatus according to claim 1.
  4. A registration sensor configured in the image forming unit for detecting the presence or absence of a sheet in a registration roller for conveying the sheet to the transfer position;
    The control means is
    Recognizing that the paper feed start command is activated after the image forming signal is activated, and among the plurality of paper feed options, the cassette of the paper feed option designated by the paper feed start command The speed is calculated from the distance and time from the registration sensor to the registration sensor.
    The image forming apparatus according to claim 1.
  5. Constructed in at least one of the plurality of paper feed options, a transport path sensor for detecting the presence or absence of a sheet in the transport path, and in the image forming unit, and a sheet at the transfer position A registration sensor for detecting the presence or absence of a sheet in the registration roller for conveying,
    The control means is
    After the paper feed start command is activated, it recognizes that the image forming signal is activated, recognizes the position of the sheet in the conveyance path by the conveyance path sensor, and starts from the recognized sheet position. Calculate the speed from the distance and time to the registration sensor,
    When the sheet reaches the transport path sensor configured in the paper feed option closest to the image forming unit among the plurality of paper feed options, the speed is determined based on the distance and time from the transport path sensor to the registration sensor. calculate,
    The image forming apparatus according to claim 1.
  6. A cassette for storing sheets; a plurality of sheet feeding options having a transport path and rollers for transporting the sheets; and an image forming unit for forming a toner image, wherein the sheets stored in the cassette are transferred to the transport path. An image forming method for conveying a formed toner image to a transfer position for transferring to a sheet via
    An image forming signal indicating that the image forming unit has started forming a toner image and a paper feed start command indicating a command to start feeding from the cassette to the transport path are input from the image forming unit, Further, when the image forming signal and the paper feed start command are activated, the speed at which the sheet is conveyed in the conveyance path is calculated according to the distance from the position of the sheet being conveyed to the transfer position, A control step of controlling a driving unit that drives the roller based on the speed, and the speed is a speed at which the transfer of the toner image and the conveyance of the sheet are synchronized at the transfer position.
JP2007123893A 2007-05-08 2007-05-08 Image forming apparatus and method Withdrawn JP2008281656A (en)

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Application Number Priority Date Filing Date Title
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Applications Claiming Priority (1)

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JP2007123893A JP2008281656A (en) 2007-05-08 2007-05-08 Image forming apparatus and method

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101891073A (en) * 2009-05-21 2010-11-24 京瓷美达株式会社 Image processing system
US9056737B2 (en) 2010-01-19 2015-06-16 Ricoh Company, Ltd. Image forming apparatus, image forming method, and storage medium
JP2016014787A (en) * 2014-07-02 2016-01-28 キヤノン株式会社 Image forming apparatus, option device and image forming system
JP2016124640A (en) * 2014-12-26 2016-07-11 キヤノン株式会社 Image formation system and feeding system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101891073A (en) * 2009-05-21 2010-11-24 京瓷美达株式会社 Image processing system
US9056737B2 (en) 2010-01-19 2015-06-16 Ricoh Company, Ltd. Image forming apparatus, image forming method, and storage medium
JP2016014787A (en) * 2014-07-02 2016-01-28 キヤノン株式会社 Image forming apparatus, option device and image forming system
JP2016124640A (en) * 2014-12-26 2016-07-11 キヤノン株式会社 Image formation system and feeding system

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