JP2004317806A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately form an image in a specified position on paper regardless of the type or the carried speed of the paper by providing a compensation value for of misalignment for each type and carrying speed of the paper even, in an image forming apparatus not using a horizontal registration sensor. <P>SOLUTION: One or more paper feeding means to store and carry paper, a paper type discriminating means discriminating the type of fed paper and a compensation value storing means to which the compensation value indicating the amount of misalignment in the direction orthogonal to the paper carried direction from an image recording start position are provided in the image forming apparatus and the image recording start position is compensated by the compensation value above. A plurality of compensation values are stored for each type of paper and the compensation value above is changed over according to the type of the paper discriminated by the paper type discriminating means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet conveying device that corrects a position of a sheet in a width direction, and is applied to an image forming apparatus such as a printer, a facsimile, and a copying machine.
[0002]
[Prior art]
Conventionally, in an image forming apparatus, there is a possibility that a position in a direction intersecting a conveying direction of a sheet may vary due to various factors. For example, the paper transport unit is detachable from the image forming apparatus main body so that jam processing can be easily performed. When the paper transport unit is forcibly inserted into the image forming apparatus main body by the user after the jam clearance, the rail guiding the paper transport unit may be deformed, or the paper transport unit itself may be deformed. In such a case, the position of the sheet may be shifted in a direction crossing the sheet transport direction. In addition, if the floor on which the main body of the image forming apparatus is installed is not flat, the main body of the image forming apparatus may be distorted and the position of the sheet may be shifted in a direction intersecting the sheet conveying direction.
[0003]
Therefore, in order to form an image at an appropriate position on the sheet, a lateral registration correction for correcting the position of the sheet in a direction intersecting with the sheet conveying direction is performed. In the lateral registration correction, the position of the conveyed sheet in the lateral direction (direction intersecting with the sheet conveyance direction) is detected by a detection unit, and the control device determines the image forming position with respect to the sheet conveyance direction based on the position information. This is done so that it can be moved in the crossing direction.
[0004]
On the other hand, the method of detecting the amount of displacement of the lateral registration by a sensor may increase the number of components, leading to an increase in cost. Therefore, a method has been adopted in which data (correction value) relating to the deviation amount for each paper feed stage is recorded in advance in a nonvolatile storage device, and the position of image writing is corrected in a direction intersecting the transport direction. I have. In this system, even if the shift amount changes for each paper feed stage due to the above-described factors, it can be rewritten by a service person.
[0005]
[Problems to be solved by the invention]
In image forming apparatuses, it is constantly required to achieve high image quality, and it is required to accurately form an image at a predetermined position on a sheet. In addition, sheets are required to form images on various types of paper, such as plain paper, resin thin paper, thick paper, postcards, envelopes, label paper, and OHP sheets, which are substitutes for plain paper. However, depending on the type of paper, the amount of deviation in the direction crossing the transport direction during transport may be larger than that of normal paper. Further, in the case where the paper is fed at a reduced transport speed in consideration of the toner fixability, the amount of deviation in a direction intersecting the transport direction may vary during transport. For this reason, it is required that an image be accurately formed at a predetermined position on a sheet, regardless of the type of the sheet and the transport speed of the sheet.
[0006]
[Means for Solving the Problems]
Therefore, in the present invention, as means for achieving low cost and high image quality,
According to the first aspect, one or more paper feed stages for storing and transporting the paper, paper type identification means for identifying the type of paper to be fed, and intersecting the paper transport direction from the image recording start position. The image forming apparatus further includes a correction value storage unit that stores a correction value indicating the amount of deviation in the direction in advance, and corrects a writing start position of an image using the correction value. The correction values are stored in advance and are switched according to the type of paper identified by the paper type identification means.
[0007]
According to a second aspect, in the first aspect, a plurality of correction values for each paper feed stage are recorded, and the correction of the image writing start position is performed by correcting the correction value depending on the type of the paper and the paper feed stage. And the correction value is added.
[0008]
According to a third aspect of the present invention, one or more paper feed stages for storing and transporting the paper, a transport speed control means for switching a transport speed of the paper according to image forming conditions, and a paper feed direction from an image recording start position. An image forming apparatus comprising a correction value storage unit for preliminarily storing a correction value indicating a shift amount in an intersecting direction, and correcting an image writing start position by the correction value. The correction values are switched according to the paper conveyance speed.
[0009]
According to a fourth aspect, in the third aspect, a plurality of correction values for each paper feed stage are recorded, and the correction of the image writing start position is performed by correcting the correction value based on the paper transport speed and the paper feed stage. The correction is performed using a value obtained by adding each correction value.
According to a fifth aspect of the present invention, in the third and fourth aspects, there is further provided a paper type identification means for identifying the type of paper to be fed, and the transport speed is determined by the type of paper to be fed.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a copying apparatus according to claims 1 to 5 of the present invention will be described with reference to embodiments.
[0011]
FIG. 1 is a cross-sectional view showing the configuration of a copying apparatus. The configuration and operation will be described with reference to FIG.
[0012]
The image forming apparatus 100 according to the embodiment of the present invention includes a document feeder 1000, an image reader 200, a printer 300, an operation unit 102, a folding processing unit 400, and a finisher 500.
[0013]
The above-described configuration will be described in detail together with the operation. The document feeder 1000 conveys the set documents one by one sequentially from the top page on the platen glass 102 from left to right through a curved path, and thereafter, Is discharged to the paper discharge tray 112. At this time, the scanner unit 104 is held at a predetermined position, and the document is read by passing the document from left to right on the scanner unit 104. When the document passes, the light of the lamp 103 of the scanner unit 104 is irradiated on the document, and the reflected light from the document is guided to the image sensor 109 via the mirrors 105, 106, 107 and the lens 108. Note that the original can be read by moving the scanner unit 104 from left to right after the original is conveyed onto the platen glass 102 by the original feeding device 1000 and stopped.
[0014]
The image of the document read by the image sensor 109 is subjected to image processing and sent to the exposure control unit 110. Exposure control section 110 outputs laser light according to the image signal. The laser beam is of a two-beam type, so that a maximum of two dots can be exposed in one scan in the main scanning direction. When the transport speed is half, the laser beam can be switched to the one-beam type. The laser beam is applied to the photosensitive drum 111, and an electrostatic latent image is formed on the photosensitive drum 111. The electrostatic latent image on the photosensitive drum 111 is developed by the toner of the developing device 113, and the toner on the photosensitive drum 111 is a sheet fed from any one of the cassettes 114 and 115, the manual sheet feeding unit 125, and the duplex conveying path 124. Is transferred by the transfer unit 116.
[0015]
The sheet to which the toner has been transferred is subjected to developer fixing processing in a fixing unit 117. The sheet that has passed the fixing unit 117 is once guided to a path 122 by the flapper 121, and after the trailing end of the sheet has passed through the flapper 121, the sheet is switched back and guided to the discharge roller 118 by the flapper 121. As a result, the developer is discharged from the printer 300 by the discharge roller 118 with the surface onto which the developer has been transferred facing downward (face down).
[0016]
When forming an image on a hard sheet such as an OHP sheet from the manual sheet feeding unit 125, the surface on which the toner has been transferred is discharged from the discharge roller 118 in an upward state (face-up) without leading to the path 122. When forming an image on both sides of the sheet, the sheet is guided straight from the fixing unit 117 to the discharge roller 118, and the sheet is switched back immediately after the trailing edge of the sheet has passed through the flapper 121. Lead to 124.
[0017]
The sheet discharged from the discharge roller 118 is sent to the folding device 400. The folding device 400 performs a process of folding a sheet into a Z shape. When a folding process is designated for an A3 size or B4 size sheet, the folding device 400 performs the folding process, and the other sheets are sent to the finisher main body 500 as they are. The finisher main body 500 performs bookbinding processing, binding processing, processing such as punching, and the like. In addition, an inserter 1900 is provided on the finisher 500, and feeds a cover, a slip sheet, and the like to the finisher main body 500.
[0018]
FIG. 2 is a diagram illustrating a key layout of the operation unit 102 attached to the reader unit 200 shown in FIG. In the figure, reference numeral 301 denotes a power switch, which controls energization of the main body. Reference numeral 302 denotes a preheating key which is depressed when switching ON / OFF of the preheating mode. Function keys 303 to 306 function as hard keys, and are keys for selecting functions to be displayed on the touch panel 316 described later. A fax mode key 305 is pressed to select a fax mode from a plurality of functions. An extension key 306 is pressed when performing an operation on the PDL. A copy start key 307 is pressed to instruct the start of copying. Reference numeral 308 denotes a stop key which is pressed when copying is interrupted or stopped. Reference numeral 309 denotes a reset key, which returns to the standard mode when the reset key is pressed during standby. Reference numeral 310 denotes a guide key which is pressed to display a description of each function. A user mode key 311 is depressed when the user changes the basic settings of the system. The closing operation mode of the present invention can be set from here. Reference numeral 312 denotes an interrupt key, which is depressed when an interrupt is required during copying and another copy is to be executed. Reference numeral 313 denotes a numeric keypad, which is a group of keys used when inputting numerical values. A clear key 314 is depressed when clearing a numerical value. An ID key 315 is pressed to shift to an ID input mode when using a copying machine. Reference numeral 316 denotes a touch panel (operation panel) composed of a combination of a liquid crystal screen and a touch sensor, in which an individual setting screen is displayed for each mode, and further, when the user touches soft keys drawn as described later, Can be set in detail. Reference numeral 317 denotes a tally lamp, which indicates a communication state with the network, normally lights up in green, blinks in green when communication is being performed, and lights in red in the case of a network error.
[0019]
FIG. 3 is a view for explaining an example of a copy standard screen displayed on the touch panel 316 shown in FIG. 2. In the image forming apparatus according to the present embodiment, the power supply is started on the copy standard screen as a default when the power is turned on. ing. In the figure, reference numeral 400 denotes a copy standard screen. A message line 401 displays the status of the copy job as a message. Reference numeral 402 denotes a magnification display, which displays the magnification automatically determined by the set magnification or the copy mode in percentage. Reference numeral 403 denotes a paper size display, which displays the size of the selected output paper. If automatic paper selection is set, a message "auto paper" is displayed. Numeral 404 indicates the number of copies to be displayed. Reference numeral 405 denotes a reduction key, which is pressed when performing reduction copy. Reference numeral 406 denotes an equal-magnification key, which is depressed when returning to equal magnification when reduction or enlargement is set. An enlargement key 407 is depressed when an enlargement copy is desired. Reference numeral 408 denotes a zoom key which is depressed when a reduction or enlargement copy is to be performed by setting a magnification in fine units. A paper selection key 409 is pressed to specify an output paper. A sorter key 410 is pressed to set a sort or staple mode.
A double-sided key 411 is pressed to set a double-sided mode. Reference numeral 412 denotes a density display, which is displayed so that the current print density can be recognized. When the marker 412a is displayed on the left side, the density is low, and when displayed on the right side, the density is high. The display of the density display 412 changes in conjunction with the thin key 413 and the dark key 415. A light key 413 is depressed when it is desired to reduce the density. An automatic key 414 is pressed when a mode for automatically determining the density is used. A body key 415 is pressed to increase the density. A character key 416 is pressed to set a character mode for automatically setting a density suitable for copying a character document. A character / photograph key 417 is depressed when setting a character / photograph mode for automatically setting a density suitable for copying an original containing a mixture of photographs. An application mode key 418 is pressed to set various copy modes that cannot be set on the copy standard screen 400. A print status key 419 is pressed to display the status of the print currently being performed in the digital copier main body 101. The print status key 419 is always displayed at this position of the touch panel 316, not only when the copy standard screen 400 is displayed on the touch panel 316, and is always displayed when the print status key 419 is pressed. Is displayed so that the print status can be viewed. Each of the above keys functions as a soft key.
[0020]
Next, FIG. 4 shows the configuration of the image writing start position correction control in the present invention. The printer 100 is controlled by the control unit shown in FIG. 4 to form an image. The paper type identification means inside the printer is a part for identifying the paper type for each paper feed stage from a dial-type switch attached to the paper feed unit of the printer or from information received from the control unit. The image writing start position correction control means is a control means for determining a laser reference position with respect to the photoconductor by a method described later. The transport speed control means is a control for determining a transport speed such as, for example, reducing the transport speed to a half speed if the paper type is OHP / thick paper, according to conditions related to image formation. The correction value storage device is a device in which various correction values used by an image writing start position correction unit described later are stored in a nonvolatile memory in advance. This storage device may be a ROM or a RAM. The correction value storage device stores correction values based on paper types such as plain paper, thick paper, thin paper, OHP, postcards, and envelopes, correction values based on paper feed stages such as paper feed stages 1 to 6, and transport speeds such as constant speed and half speed. Has a correction ground by speed. At this time, the correction value based on the paper feed stage is a correction value for a shift in a direction intersecting the transport direction with the paper supply unit mounted, and the correction value based on the paper type or the transport speed is a transport value generated during paper transport. A correction value for a deviation in a direction crossing the direction is registered in advance.
[0021]
Next, FIG. 5 shows the flow of the image writing start position correction control in the present invention. First, when receiving an image formation start command from the control unit (S1000), the printer 100 clears the image writing start position correction value (S1001). Next, when the printer unit receives a paper feed command including paper feed stage information from the control unit, the printer unit identifies the paper feed stage to be fed (S1002), and sets the correction value of the corresponding paper feed stage to the image writing start position correction. The value is added to the value (S1003 to S1008). Next, the paper type identification means identifies the paper type from the preceding paper feed stage information (S1009), and adds a correction value based on the corresponding paper type to the image writing start position correction value (S1010 to S1015). Next, if the paper type is OHP / thick paper, the transport speed control means determines that the transport speed should be reduced if the paper type is OHP or thick paper, and if not, feeds at the normal transport speed (S1016). Based on the determination result, the correction value based on the corresponding transport speed is added to the image writing start position correction value (S1017, S1018). Before starting the image writing (S1020), the image writing start position correction value is written in the register for controlling the laser writing (S1019), whereby the image can be printed in an appropriate range of the paper.
[0022]
【The invention's effect】
As described above, according to the present invention, even in an image forming apparatus that does not use a lateral registration sensor, by providing a correction value of the shift amount for each type of paper and each transport speed, regardless of the type of paper and the transport speed, An image can be accurately formed at a predetermined position on a sheet.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an image forming apparatus of the present invention.
FIG. 2 is a diagram showing an operation unit of the present invention.
FIG. 3 is a diagram showing a display unit of the present invention.
FIG. 4 is a diagram showing a device configuration of the present invention.
FIG. 5 is a diagram illustrating control of image writing start position correction according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Image forming apparatus 102 Platen glass 103 Lamp 104 Scanner units 105, 106, 107 Mirror 108 Lens 109 Image sensor 200 Image reader 300 Printer 400 Folding unit 500 Finisher 1000 Document feeder

Claims (5)

One or more paper trays for storing and transporting paper;
Paper type identification means for identifying the type of paper to be fed;
A correction value storage unit that records in advance a correction value indicating a shift amount in a direction intersecting with the sheet conveyance direction from the image recording start position,
In an image forming apparatus for correcting a writing start position of an image by the correction value,
A plurality of the above correction values are stored for each type of paper,
An image forming apparatus, wherein the correction value is switched according to the type of paper identified by the paper type identification unit. In claim 1,
Record a plurality of correction values for each paper feed stage,
The image forming apparatus according to claim 1, wherein the correction of the image writing start position is performed by adding a correction value based on the type of the paper and a correction value for each paper feed stage. One or more paper trays for storing and transporting paper;
Transport speed control means for switching the transport speed of the paper according to image forming conditions,
A correction value storage unit that records in advance a correction value indicating a shift amount in a direction intersecting with the sheet conveyance direction from the image recording start position,
In an image forming apparatus for correcting a writing start position of an image by the correction value,
A plurality of the above correction values are stored for each transport speed,
An image forming apparatus, wherein the correction value is switched according to a sheet conveying speed. In claim 3,
Record a plurality of correction values for each paper feed stage,
The image forming apparatus according to claim 1, wherein the correction of the image writing start position is performed by adding a correction value based on the transport speed of the sheet and a correction value for each paper feed stage. In claims 3 and 4,
Further comprising a paper type identification means for identifying the type of paper to be fed,
An image forming apparatus wherein the transport speed is determined according to the type of paper to be fed.

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