JP2013011737A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a paper feeding delay is prevented as much as possible and reduction in productivity due to the prevention of paper feeding is suppressed to the minimum.SOLUTION: In an image forming apparatus includes a control part that primarily feeds a sheet to a sheet standby position by controlling a primary sheet feeding part, forms a toner image by controlling a toner image formation part, and secondarily feeds the sheet waiting at the sheet standby position to a transfer part by controlling a secondary sheet feeding part at a prescribed timing from the formation of the toner image, the control part measures a time difference between the timing when the sheet arrives at the sheet standby position and a prescribed timing from the formation of the toner image, as a secondary sheet feeding waiting time, and delays the formation start timing of the toner image by the toner image formation part when the measured value falls below a prescribed lower limit value.

Description

 The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copier or a multifunction machine, a sheet is not transported to a specific location (for example, immediately before a registration roller) on the sheet transport path at a timing at which a toner image should be transferred to the sheet. It becomes “paper delay”, and it is necessary to discard the formed toner image once and form the same toner image again.
Also, once this paper delay occurs, it is likely to occur continuously unless the cause (for example, the occurrence of “slip” due to aging of the paper feed roller or dust adhesion) is removed. This is a factor that significantly reduces productivity.

  In the following Patent Document 1, when the occurrence of a paper delay is detected, the image forming speed of the image forming unit is delayed, and then the number of sheets in which the paper delay has occurred during the execution of the next job exceeds a predetermined threshold. A technique is disclosed in which the deterioration state of the sheet feeding unit is determined based on whether or not the image forming unit has been deteriorated, and the delayed image forming speed is restored according to the determination result.

JP 2009-139725 A

  In the above-described prior art, after the paper delay has already occurred, the image forming speed by the image forming unit is delayed, so the first paper delay cannot be prevented in advance. In addition, during the next job execution, the deterioration state of the paper feeding unit is determined, and the delayed image formation speed is restored according to the determination result. Therefore, from the middle of the job in which the image formation speed is delayed, The state where productivity is reduced over the job continues more than necessary.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to prevent paper delay as much as possible and to minimize a decrease in productivity due to prevention of paper delay.

 In order to solve the above-described problems, in the present invention, as a first solving means related to an image forming apparatus, a toner image forming unit that forms a toner image based on image data, and a transfer unit that transfers the toner image to a sheet A primary paper feeding unit that primarily feeds the paper to a paper standby position on a paper conveyance path to the transfer unit; and a secondary paper feeding unit that waits at the paper standby position to the transfer unit. Forming the toner image by controlling the primary paper feed unit and the primary paper feed unit to feed the paper to the paper standby position, and controlling the toner image forming unit to form the toner image. An image forming apparatus comprising: a control unit that controls the secondary paper feeding unit at a predetermined timing to cause the paper that is waiting at the paper standby position to be secondary fed to the transfer unit; The control unit is the paper standby position When the time difference between the timing when the paper arrives and the predetermined timing from the formation of the toner image is measured as a secondary paper feed waiting time, and the measured value is less than or equal to a preset lower limit value, the toner The toner image formation start timing by the image forming unit is delayed.

 According to the present invention, as the second solving means relating to the image forming apparatus, in the first solving means, the control unit is configured such that the measured value of the secondary paper feeding waiting time is equal to or less than the lower limit value. Then, the productivity defined by the number of printable sheets per unit time is recalculated according to the preset target value of the secondary paper feed waiting time, and the toner image formation start timing is determined according to the calculation result. The delay amount is set.

  In the present invention, as a third solving means relating to the image forming apparatus, in the first or second solving means, the control unit delays the toner image formation start timing and then supplies the paper. The number of sheets is counted, and the formation start timing of the toner image is restored according to the count result.

  According to the present invention, it is possible to prevent paper delay as much as possible, and to minimize a decrease in productivity due to prevention of paper delay.

1 is a schematic configuration diagram of a multifunction peripheral A according to an embodiment of the present invention. 6 is a timing chart illustrating a temporal correspondence relationship between a sheet feeding operation and an image forming operation of the multifunction peripheral A. 7 is a flowchart showing paper delay prevention control by a control unit 6; FIG. 10 is a supplementary explanatory diagram regarding an example of a method for setting a delay amount of the toner image formation start timing.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Hereinafter, as an image forming apparatus according to the present invention, a multi-function machine having functions such as a copier, a printer, a scanner, and a facsimile will be described as an example.
FIG. 1 is a schematic configuration diagram of a multifunction peripheral A according to the present embodiment. As shown in FIG. 1, the MFP A includes an operation display unit 1, an image reading unit 2, an image data storage unit 3, a paper transport image forming unit 4, a communication unit 5, and a control unit 6.

   The operation display unit 1 includes operation keys and a touch panel, and functions as a man-machine interface that associates the user with the multifunction peripheral A. The operation display unit 1 outputs an operation instruction of a pressed operation key or an operation button displayed on the touch panel to the control unit 6 and displays various screens on the touch panel based on a control signal input from the control unit 6. indicate.

   Under the control of the control unit 6, the image reading unit 2 reads a surface image (original image) of a document automatically fed by an ADF (Auto document feeder) or a document placed on a platen glass with a line sensor. The document image data is converted into document image data, and the document image data is output to the control unit 6. The image reading unit 2 outputs the document image data to the control unit 6, while the control unit 6 stores the document image data in the image data storage unit 3.

   The image data storage unit 3 is a semiconductor memory, a hard disk device, or the like. Document image data based on a control signal input from the control unit 6 or a print image received by the communication unit 5 from an external client computer (not shown). Data and facsimile image data received from the facsimile apparatus by the communication unit 5 are stored.

   Under the control of the control unit 6, the sheet transport image forming unit 4 transports sheets one by one from the sheet bundle stored in the sheet feeding cassette 44, and puts them on the sheet based on the image data in the image data storage unit 3. An image is formed. As shown in FIG. 1, the sheet transport image forming unit 4 has an image forming unit 41 that forms an image (hereinafter referred to as a toner image) made of toner corresponding to four colors of black, yellow, cyan, and magenta. , Intermediate transfer belt 42, primary transfer roller 43, paper feed cassette 44, paper feed roller 45, transport roller 46, registration roller 47, registration sensor 48, secondary transfer roller 49, fixing roller 50, paper discharge roller 51 and discharge The paper tray 52 is configured.

 Of the components of the paper transport image forming unit 4, the image forming unit 41, the intermediate transfer belt 42, and the primary transfer roller 43 correspond to the toner image forming unit in the present embodiment, and the secondary transfer roller 49 performs the present operation. The sheet feeding roller 45 and the transport roller 46 correspond to the primary sheet feeding unit in the present embodiment, and the registration roller 47 corresponds to the secondary sheet feeding unit in the present embodiment.

   Each image forming unit 41 forms a toner image corresponding to each color of yellow, magenta, cyan, and black. Four image forming units 41 are provided corresponding to each color at predetermined intervals in the horizontal direction when viewed from the front of the multi-function peripheral A. It has been. As shown in FIG. 1, the image forming unit 41 includes a photosensitive drum 41a on which a toner image is formed on the peripheral surface.

   The intermediate transfer belt 42 is an endless belt provided so as to be in contact with each photoconductive drum 41a, and a toner image formed on the peripheral surface of each photoconductive drum 41a is primarily transferred from each photoconductive drum 41a. It is. The primary transfer roller 43 is disposed so as to face each of the photoconductive drums 41a so as to sandwich the intermediate transfer belt 42. The primary transfer roller 43 is rotated from the photoconductive drum 41a by applying a primary transfer voltage to the intermediate transfer belt 42 while rotating. A roller that primarily transfers the toner image to the intermediate transfer belt 42.

The paper feed cassette 44 is a container for storing sheets of a predetermined size such as A4 size and B5 size in a bundle shape, and has an opening for exposing the uppermost surface of the sheets stacked in a bundle shape. The paper feed roller 45 feeds the paper from the paper feed cassette 44 to the paper transport path L one by one by rotating in the paper feed direction while being pressed against the uppermost surface of the paper stacked in a bundle on the paper feed cassette 44. It is a roller. Here, the paper feed direction refers to the direction in which the paper is transported along the paper transport path L.
A rotation drive mechanism (such as a motor or a reduction gear) (not shown) is connected to the rotation shaft of the sheet feed roller 45, and the sheet feed roller 45 is rotated (start timing, stop timing, rotation, etc.). The speed and the like are controlled by the control of the rotation drive mechanism (particularly motor control) by the control unit 6.

The transport roller 46 is disposed on the downstream side of the paper feed roller 45 on the paper transport path L, and rotates in the paper feed direction to transport the paper sent to the paper transport path L by the paper feed roller 45. It is conveyed to the downstream side of the path L.
Note that a rotation drive mechanism (such as a motor and a reduction gear) (not shown) is connected to the rotation shaft of the conveyance roller 46, and the rotation operation (rotation start timing, stop timing, rotation speed, etc.) of the conveyance roller 46 is performed. ) Is controlled by the control of the rotation drive mechanism (particularly motor control) by the controller 6. A configuration in which the rotational force of the paper feed roller 45 is transmitted to the rotation shaft of the transport roller 46 by a belt may be employed.

On the downstream side of the conveyance roller 46 on the sheet conveyance path L, a pair of registration rollers 47 for adjusting the conveyance timing of the sheet to the secondary transfer roller 49 are arranged. The pair of registration rollers 47 is composed of two rollers that face each other and rotate in the paper feeding direction while being pressed against each other.
Note that a rotation drive mechanism (not shown) (a motor, a reduction gear, etc.) is connected to the rotation shaft of one of the registration rollers 47, and the other roller is idled. That is, the rotation operation (rotation start timing, stop timing, rotation speed, etc.) of one roller is controlled by the control of the rotation drive mechanism (particularly motor control) by the control unit 6, and the other roller is driven by one roller. It is like that.

 The registration sensor 48 is disposed immediately before the registration roller 47 on the paper transport path L, detects the presence or absence of paper at this position (paper standby position), and outputs a signal corresponding to the detection result to the control unit 6. To do. For example, the registration sensor 48 outputs an on signal (high level signal) when a sheet is present at the sheet standby position, and outputs an off signal (low level signal) when there is no sheet.

 The secondary transfer roller 49 is a roller that is disposed so as to sandwich the intermediate transfer belt 42 between the opposing transfer rollers and that forms a secondary transfer nip with the intermediate transfer belt 42. The intermediate transfer belt The toner image on 42 is secondarily transferred to a sheet. That is, the secondary transfer roller 49 applies the secondary transfer voltage while the intermediate transfer belt 42 and the paper are sandwiched at the secondary transfer nip, thereby secondary transfer of the toner image on the intermediate transfer belt 42 to the paper. Let

   The fixing roller 50 includes a heating roller having a heater therein and a pressure roller pressed against the heating roller. The fixing roller 50 sandwiches the paper on which the toner image is secondarily transferred by the secondary transfer roller 49. Thus, the toner image is fixed on the paper by heating and pressurizing the paper. The paper discharge roller 51 discharges the paper conveyed from the fixing roller 50 to the paper discharge tray 52. The paper discharge tray 52 is a tray that stores the paper discharged by the paper discharge roller 51.

  The communication unit 5 communicates with an external multifunction peripheral or facsimile apparatus via a telephone line based on a control signal input from the control unit 6, or with a client computer via a local area network. That is, the communication unit 5 has a communication function compliant with a LAN standard such as Ethernet (registered trademark) and a communication function compliant with a facsimile standard such as G3. The communication unit 5 performs e-mail transmission or facsimile transmission / reception, for example.

  The control unit 6 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an interface circuit that transmits and receives various signals to and from the above-described units, and is stored in the ROM. The overall operation of the multifunction device A is controlled based on the control program.

Next, the operation of the multifunction peripheral A configured as described above will be described.
FIG. 2 is a timing chart showing the temporal correspondence between the paper feeding operation and the image forming operation (toner image forming operation) of the multifunction peripheral A. For example, when the copy start key of the operation display unit 1 is pressed, the control unit 6 causes the image reading unit 2 to read a document image and causes the image data storage unit 3 to store document image data obtained from the image reading unit 2. After that, the sheet feeding operation is started at the sheet feeding start timing t1 shown in FIG.

 Specifically, the control unit 6 rotates the paper feed roller 45 and the transport roller 46 while the registration roller 47 is stopped, so that the paper standby position (registration) on the paper transport path L from the paper feed cassette 44 is detected. One sheet of paper is primarily fed to the position immediately before the roller 47). One sheet fed from the sheet feeding cassette 44 to the sheet conveying path L by the rotation of the sheet feeding roller 45 is conveyed along the sheet conveying path L until it hits the registration roller 47 by the rotation of the conveying roller 46. When the sheet hits the registration roller 47, that is, when the sheet reaches the position immediately before the registration roller 47 (sheet standby position), an ON signal is output from the registration sensor 48 to the control unit 6.

 The control unit 6 uses the timing at which the ON signal is input from the registration sensor 48 (t3 in FIG. 2A) as the timing at which the paper reaches the paper standby position (hereinafter referred to as the secondary paper feed preparation completion timing). recognize. The paper feed roller 45 and the transport roller 46 are already stopped at the secondary paper feed preparation completion timing t3.

 On the other hand, the control unit 6 starts an image forming operation at a time t2 (image forming start timing) slightly delayed from the paper feed start timing t1. Specifically, the control unit 6 controls each image forming unit 41 based on the document image data stored in the image data storage unit 3 to form a toner image of each color on the surface of each photoconductor drum 41a ( The toner image of each color is sequentially superimposed and transferred onto the intermediate transfer belt 42 (primary transfer). )

 The control unit 6 performs a registration roller 47 at a predetermined timing from the image formation start timing t2 or at a timing t4 when the primary transfer of the toner image on the intermediate transfer belt 42 is completed (hereinafter referred to as a secondary paper feed request timing). , The sheet waiting on the sheet standby position, that is, the position immediately before the registration roller 47 is secondarily fed to the secondary transfer roller 49. As a result, the toner image on the intermediate transfer belt 42 is secondarily transferred to the sheet, and the toner image is fixed by the fixing roller 50 and then discharged to the outside by the discharge roller 51.

 Here, as shown in FIGS. 2A and 2B, the time difference between the secondary paper feed request timing t4 and the secondary paper feed preparation completion timing t3 (hereinafter referred to as secondary paper feed waiting time TW) is obtained. If it is greater than “0”, that is, the secondary paper feed preparation completion timing t3 is earlier than the secondary paper feed request timing t4, “paper delay” does not occur and the toner image can be transferred onto the paper without any problem. it can.

 On the other hand, as shown in FIG. 2C, the time difference between the secondary paper feed request timing t4 and the secondary paper feed preparation completion timing t3 (hereinafter referred to as secondary paper feed waiting time TW) is smaller than “0”. That is, when the secondary paper feed preparation completion timing t3 is later than the secondary paper feed request timing t4, a “paper delay” occurs, and the toner image formed on the intermediate transfer belt 42 is discarded once. It is necessary to form the same toner image again.

 In order to solve such a problem, in the present embodiment, the control unit 6 calculates the time difference between the secondary paper feed request timing t4 and the secondary paper feed preparation completion timing t3 according to the control flowchart shown in FIG. Measured as the paper feed waiting time TW, and when the measured value is equal to or less than a preset lower limit value, toner from the toner image forming unit (image forming unit 41, intermediate transfer belt 42, and primary transfer roller 43) It has a function of delaying the image formation start timing (image formation start timing t2 in FIG. 2).

 Specifically, as shown in FIG. 3, when the controller 6 detects the arrival of the secondary paper feed request timing t4 (step S1), the secondary paper feed request timing t4 and the secondary paper feed preparation completion timing t3. Is measured as a secondary paper feed waiting time TW, and it is determined whether or not the measured value is equal to or less than a preset lower limit value (step S2).

 If “No” in step S2, the control unit 6 proceeds to a process in step S4 described later. If “Yes”, the control unit 6 starts the toner image formation start timing (image formation in FIG. 2). The start timing t2) is delayed by a predetermined amount (step S3). Specifically, in step S3, the control unit 6 recalculates the productivity defined by the number of printable sheets per unit time according to the preset target value of the secondary paper feed waiting time TW. Then, a delay amount of the toner image formation start timing is set according to the calculation result.

 For example, the multifunction peripheral A has a productivity (20 (page / min)) capable of printing 20 sheets per minute, and as shown in FIG. msec), the target value after detection of the lower limit is set to 100 (msec), and it is assumed that the measured value of the secondary paper feed waiting time TW is 25 (msec) lower than the lower limit value.

 Under this assumption, the time taken per sheet that can be calculated from productivity is 60 (sec) / 20 (page / min) = 3 (page / sec). If the total time is calculated from this time per sheet so as to be the target value after detection of the lower limit, 3 (page / sec) + (0.1 (page / sec) −0.025 (page / sec) ) = 3.075 (page / sec).

 When the productivity after the change is recalculated from the total time thus calculated, 60 (sec) /3.075 (page / sec) = 19.5 (page / min). That is, in this case, the control unit 6 sets the delay amount of the toner image formation start timing so that the productivity decreases from 20 (page / min) to 19.5 (page / min).

 Returning to FIG. 3, after delaying the toner image formation start timing by a predetermined amount as described above, the control unit 6 determines whether or not the toner image formation start timing has already been delayed (step S4). In the case of “No”, the present control flow is terminated, whereas in the case of “Yes”, the number of sheets fed is counted (step S5).

 Then, the control unit 6 determines whether or not the number of sheets fed has reached the specified number (step S6). If “No”, the control flow is terminated, while “Yes”. In step S7, the toner image formation start timing is returned to the original and the control flow is terminated.

As described above, according to the present embodiment, the time difference between the secondary paper feed request timing t4 and the secondary paper feed preparation completion timing t3 is measured as the secondary paper feed waiting time TW, and the measured value is set in advance. When the toner image forming unit (image forming unit 41, intermediate transfer belt 42, and primary transfer roller 43) starts to delay the toner image formation start timing when the lower limit is reached, the paper delay tends to occur. It is possible to prevent paper delay as much as possible while detecting the error.
Further, according to the present embodiment, after delaying the toner image formation start timing, the number of sheets fed is counted, and the toner image formation start timing is restored according to the count result, thereby preventing paper delay. The decrease in productivity due to can be minimized.

In addition, this invention is not limited to the said embodiment, The following modifications are mentioned.
For example, in the above embodiment, the case where the toner image formation start timing is returned to the original when the number of sheets fed reaches a specified number is exemplified. However, the toner image formation is gradually performed as the number of sheets fed increases. The start timing may be restored.
In the above-described embodiment, the image forming apparatus according to the present invention has been described with reference to the multifunction peripheral A. However, the present invention is not limited to this and is applied to other image forming apparatuses such as a copier, a printer, and a facsimile machine. can do.

 A ... multifunction device, 1 ... operation display unit, 2 ... image reading unit, 3 ... image data storage unit, 4 ... paper transport image forming unit, 5 ... communication unit, 6 ... control unit, 41 ... image forming unit, 42 ... Intermediate transfer belt, 43 ... primary transfer roller, 44 ... paper feed cassette, 45 ... paper feed roller, 46 ... transport roller, 47 ... registration roller, 48 ... registration sensor, 49 ... secondary transfer roller, 50 ... fixing roller, 51: Paper discharge roller, 52 ... Paper discharge tray

Claims (3)

A toner image forming unit that forms a toner image based on image data;
A transfer unit for transferring the toner image to a sheet;
A primary paper feeding unit that primarily feeds the paper to a paper standby position of a paper conveyance path to the transfer unit;
A secondary paper feeding unit that secondary feeds the paper waiting at the paper standby position to the transfer unit;
The primary paper feed unit is controlled to feed the paper to the paper standby position, and the toner image forming unit is controlled to form the toner image. The toner image is formed at a predetermined timing from the formation of the toner image. A control unit for controlling a secondary paper feeding unit to secondary feed the paper on standby at the paper standby position to the transfer unit;
An image forming apparatus comprising:
The control unit measures a time difference between a timing at which the paper reaches the paper standby position and a predetermined timing from the formation of the toner image as a secondary paper feed waiting time, and the measurement value is a preset lower limit. An image forming apparatus that delays the toner image formation start timing by the toner image forming unit when the value is equal to or less than a value.   When the measured value of the secondary paper feed waiting time is less than or equal to the lower limit value, the control unit determines the number of printable sheets per unit time according to the preset target value of the secondary paper feed waiting time. The image forming apparatus according to claim 1, wherein the defined productivity is recalculated, and a delay amount of the toner image formation start timing is set according to the calculation result.   The control unit, after delaying the toner image formation start timing, counts the number of sheets fed and returns the toner image formation start timing to an original state according to the count result. Item 3. The image forming apparatus according to Item 1 or 2.

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