JP2003095461A - Sheet feeding device - Google Patents

Abstract

(57) [Summary] [Problem] To automatically adjust the interval between cut sheets to be continuously fed to an image forming section according to the type of recording paper and the use environment, and to minimize the required interval between sheets. Or multi-feed conveyance to increase the number of image formations per unit time. SOLUTION: In a sheet feeding device which has a sheet stacking section and a sheet conveying path and can feed and convey a plurality of sheets stacked on the stacking section, the sheet stacked on the stacking section is fed. Means for feeding from the stacking unit, means for adjusting the interval between the sheets when conveying a plurality of sheets, and means for conveying the plurality of sheets while maintaining the adjusted interval A sheet feeding device for automatically adjusting the sheet interval based on a condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet printer for continuously feeding cut sheets to an image forming unit in various image forming apparatuses such as a page printer such as a laser printer, a digital copying machine and a plain paper fax machine. Regarding

[0002]

2. Description of the Related Art In an image forming apparatus such as a page printer or a digital copying machine, generally, a cut sheet (transfer sheet) is fed from a sheet feeding cassette and fed to an image forming section including an image carrier. After being fed, the sheet is temporarily stopped at the time when the leading edge hits the registration roller arranged immediately before the image forming unit, and then is re-fed to the image forming unit at a predetermined timing and formed on the image carrier. I try to transfer the image.

By the way, in the conventional analog copying machine, the scanning time of the manuscript is intervened every time printing is performed on each sheet, so that it is inevitably necessary to increase the sheet interval. Further, in the page printer and the plain paper fax, it is not necessary to shorten the sheet interval because the image processing time is required for printing.

However, with the advent of digital copying machines and the speeding up and efficiency of image processing apparatuses mounted on page printers and plain paper fax machines, cut sheet sheets are continuously fed to the image forming section. There has been a demand for shortening the distance as much as possible.

Therefore, in order to solve such a problem,
For example, as disclosed in Japanese Patent Laid-Open No. 60-87359, a method has been proposed in which a trailing edge of a preceding sheet and a leading edge of a sheet following the sheet are overlapped and conveyed.

However, when it is difficult to stack and convey the sheets due to the type of the sheet such as thick paper or special paper and the environment such as humidity, it is desirable to convey the sheets without overlapping them. At the time of conveyance, it is necessary to switch whether or not the sheets are overlapped.

This problem can be solved by using a transfer method switching means as disclosed in Japanese Patent Laid-Open No. 5-289453.

[0008]

However, in the method proposed above, it is necessary to precisely control the rotation speed of the motor for conveying the sheets in order to adjust the conveying interval between the sheets. The process considering the timing for controlling the motor becomes complicated. In addition, the proposed method allows the selection of the seat interval as a measure against the frequent shift noise of the motor, and does not select the seat interval depending on the type of the seat or the environment.

The present invention has been made in view of the above points, and conveys sheets to be continuously fed to an image forming section by a sheet feeding device at a minimum necessary sheet interval according to the type and environment of the sheet. By doing so, it is an object of the present invention to improve the productivity and to reduce the production cost of the product by simplifying the mechanism of the device.

[0010]

In order to achieve the above object, the present invention includes a sheet stacking section capable of stacking a plurality of sheets and a sheet transport path capable of transporting a plurality of sheets, Means for feeding the sheets stacked on the sheet stacking unit, and adjusting the distance between the trailing edge of the preceding sheet and the leading edge of the following sheet when feeding the sheet from the sheet stacking unit. Based on the conditions for adjusting the sheet spacing, the means for widening, narrowing, and stacking the sheets, the means for transporting the sheets on the transport path while maintaining the adjusted spacing between the sheets. And means for automatically executing.

(Operation) Claims 4, 6, and 1
3. According to the sheet feeding device of claim 15, environmental information is obtained from a sensor or the like that senses the device environment such as temperature and humidity. For example, the sheet is curled due to high temperature, and the sheet interval is reduced. If adjustment is not easy or if it is not easy to separate the superposed sheets due to high humidity, it is judged that it is better to widen the sheet interval and widen the sheet interval when feeding the sheet. To send. As a result, the jam rate when the sheet is conveyed is reduced, and the error occurrence frequency of the apparatus is reduced.

Further, according to the sheet feeding device of the second, sixth and fifteenth aspects, in the mechanism for feeding the sheet from the sheet stacking portion, a conventionally adopted pickup roller mechanism is used. The mechanism itself does not become complicated because it can be realized simply by arranging the pickup roller arranged at the front end of the sheet at the rear end of the sheet.

According to the sheet feeding device of claim 5 or claim 14, the type information of the sheets stacked in the sheet stacking unit is acquired from the storage means, and for example, the type of the sheet is thick. When it is not easy to stack and convey the sheets to each other, it is determined that it is better to widen the sheet interval, and the sheet is widened before the sheet is fed. As a result, the jam rate when the sheet is conveyed is reduced, and the error occurrence frequency of the apparatus is reduced.

According to the sheet feeding device of the third aspect, in the mechanism for feeding the sheet from the sheet stacking unit, the speed of feeding the sheet from the sheet stacking unit is higher than the speed of the sheet conveyed on the conveying path. Since it can be realized only by a simple setting of speeding up, the mechanism itself does not become complicated as compared with the conventional sheet feeding apparatus.

[0015]

1 to 4 are drawings showing the configuration of an image forming apparatus according to an embodiment of the present invention. The basic configuration will be described based on them.

(Structure of Color Reader Unit) First, the structure of the color reader unit will be described.

FIG. 3 shows the overall structure of the image forming apparatus. Here, 101 is a CCD, 311 is a CCD 10
1, a control unit 300 for controlling the entire image forming apparatus, and a printer processing unit 312 including a portion of the image processing unit of FIG. 1 excluding 101 and portions of 201, 202 to 205 of FIG. 301 is a platen glass,
Reference numeral 302 denotes a document feeder (DF) (note that there is a configuration in which a mirror surface pressure plate (not shown) is mounted instead of the document feeder 302), and 303 and 304 denote light sources (halogen lamps or fluorescent lamps) for illuminating a document. , 305 and 306 are light sources 30
Reflector for collecting light of 3, 304 on the original, 307-30
9 is a mirror, and 310 is C reflected light or projected light from the original.
A lens 314 for condensing light on the CD 101 is a halogen lamp 303, 304, a reflector 305, 306, and a mirror 30.
A carriage 315 for accommodating seven mirrors 308, 30
A carriage 313 for accommodating 9 is an external interface (I / F) with another device. The carriage 314 has a speed V and the carriage 315 has a speed V / 2.
Then, the CCD 101 is mechanically moved in the direction perpendicular to the electrical scanning (main scanning) direction to scan (sub-scan) the entire surface of the document.

As shown in FIG. 4, the control unit 300 includes a digital image processing unit 312 and a printer control I / F 355.
The CPU 401, the operation unit 402, and the memory 40, each having an I / F for exchanging information for controlling
It is composed of three. The operation unit 402 is composed of a liquid crystal with a touch panel for inputting process execution contents by the operator, information regarding the process to the operator, and notification of warnings.

Next, the digital image processing section 312 will be described in detail. FIG. 1 is a block diagram showing a detailed configuration of the digital image processing unit 312.

The originals on the platen glass are light sources 303 and 30.
The light from No. 4 is reflected, and the reflected light is guided to the CCD 101 and converted into an electric signal (in the case of the CCD 101 being a color sensor, even if the RGB color filters are inline on the one-line CCD in the order of RGB, 3 line C
In the CD, the R filter, the G filter, and the B filter may be arranged for each CCD,
The filter may be on-chip, or the filter may be configured separately from the CCD).

Then, the electric signal (analog image signal) is inputted to the image processing section 312, and the clamp & Am.
p. & S / H & A / D section 102 sample hold (S
/ H), the dark level of the analog image signal is clamped to the reference potential, amplified to a predetermined amount (the above processing order is not limited to the notation order), A / D converted, and converted into, for example, RGB.
Each is converted into an 8-bit digital signal.

Then, the RGB signal is applied to the shading unit 1.
In 03, after shading correction and black correction are applied,
In the connection & MTF correction & document detection unit 104, the CCD 10
When 1 is a 3-line CCD, the reading position between the lines in the connecting process is different. Therefore, the delay amount for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading positions of the 3 lines are the same. In MTF correction, since the reading MTF changes depending on the reading speed and the scaling factor, the change is corrected,
The document detection recognizes the document size by scanning the document on the platen glass.

The digital signal whose reading position timing is corrected is input to the CCD 10 by the input masking unit 105.
1 spectral characteristics and light sources 303 and 304 and reflector 30
The spectral characteristics of 5 and 306 are corrected. Input masking section 1
The output of 05 is input to the selector 106 that can switch the external I / F signal. The signal output from the selector 106 is input to the color space compression & background removal & LOG conversion unit 107 and the background removal unit 115. The signal input to the background removal unit 115 is subjected to background removal, and then input to the black character determination unit 116 which determines whether the original is a black character in the original.
A black character signal is generated from the original.

Further, the color space compression & background removal & LOG conversion unit 107 to which the output of another selector 106 is input.
Then, in color space compression, it is judged whether the read image signal is within the range that can be reproduced by the printer, and if it is included, it is corrected as it is. . Then, the background removal processing is performed, and CMY is converted from the RGB signal by LOG conversion.
Convert to signal. Then, the output signal of the color space compression & background removal & LOG conversion unit 107 has its timing adjusted by a delay 108 in order to correct the timing of the signal generated by the black character determination unit 116.

The moiré removing section 109 removes moiré from these two types of signals, and the signal is subjected to a scaling process in the main scanning direction at 110. 111 is a UCR & masking & black character reflection part,
As for the signal processed by the scaling processing unit, the CMY signal is generated as a CMYK signal by the UCR processing, and the masking processing unit corrects the CMYK signal to a signal that is output from the printer. It is fed back to the CMYK signals. UCR & Masking & Black Character Reflection 1
The signal processed in 11 is subjected to density adjustment in the γ correction unit 112 and then smoothed or edge processed in the filter unit 113. The processed signal is converted from an 8-bit multi-valued signal into a binary signal in the binary conversion unit 201 (the conversion method may be any of the dither method, the error diffusion method, and the improved error diffusion). .

(Configuration of Printer Unit) Next, the configuration of the printer unit will be described. In FIG. 3, reference numeral 355 is a printer control I / F, which serves as a port for receiving a control signal from the CPU 401 of the color reader unit. The printer unit performs the operation described below based on the control signal from the printer control I / F 355.

Next, the image forming section will be described in detail. In FIG. 3, 317 is an M image forming unit, 318 is a C image forming unit, 319 is an M image forming unit, and 320 is a K image forming unit. Since all the image forming units 317 to 320 have the same configuration, the M image forming unit 317 will be described in detail below, and description of the other image forming units will be omitted.

In the M image forming section 317, a photosensitive drum 342 forms a latent image on its surface by the light from the LED array 210. Reference numeral 321 denotes primary electricity, which charges the surface of the photosensitive drum 342 to a predetermined potential to prepare for latent image formation. A developing unit 322 is a photosensitive drum 342.
The upper latent image is developed to form a toner image.

The developing device 322 includes a sleeve 345 for applying a developing bias for developing. Reference numeral 323 denotes a transfer charge, which discharges electricity from the back surface of the transfer belt 333 and transfers the toner image on the photosensitive drum 342 to a recording paper or the like on the transfer belt 333. In this embodiment, since the transfer efficiency is good, the cleaner portion is not arranged (it goes without saying that there is no problem even if the cleaner portion is attached).

Finally, a procedure for forming an image on a sheet (recording paper) will be described.

First, the sheets and the like stored in the cassettes 340 and 341 are picked up by pickup rollers 339 and 338 rotated by a driving means (not shown). At that time, the pickup rollers 339 and 338 are picked up.
Picks up while pushing out by rotating in pressure contact with the trailing edge of the recording paper. Therefore, it is possible to pick up the succeeding sheet before the preceding sheet is completely fed from the cassettes 340 and 341, so that it is possible to make the leading end position interval of the consecutive sheets shorter than the sheet length. As a result, it becomes possible to carry out the conveyance with the minimum required space between sheets, and to carry out continuous conveyance in a state where a plurality of sheets are overlapped, that is, double feed conveyance. FIG. 5 schematically shows the state of the sheets that are being double-fed and conveyed.

The procedure for adjusting the interval between a plurality of conveyed sheets, which is a feature of the present embodiment, will now be described.

In FIG. 6, when the distance between the sheets is long (a)
And the operation of each part in case (b) is short. In FIG.
The procedure for adjusting the timing T at which the feeding start command is issued will be described. For the type of sheets in FIG. 7, the type of sheets stacked in the sheet stacking unit is input from the operation unit 402 and stored in the memory is referred to. Depending on the type of the referenced sheet, it is determined whether it is OHP or thick paper, and if the sheets stacked in the sheet stacking unit are OHP or thick paper, the feeding timing is set to OHP and the sheet interval is set long for thick paper. If the sheet is plain paper, the sheet interval is set to be short for plain paper.

The sheet fed onto the transfer belt 333 after the roller 336 is charged by the adsorption charger 346. A transfer belt roller 348 drives the transfer belt 333 and charges the sheet or the like by pairing with the adsorption charger 346 to adsorb the sheet or the like to the transfer belt 333. A sheet leading edge sensor 347 detects the leading edge of a sheet or the like on the transfer belt 333. The detection signal of the sheet leading edge sensor is sent from the printer section to the color reader section and is used as a sub-scanning synchronization signal when sending a video signal from the color reader section to the printer section.

After that, the sheet or the like is conveyed by the transfer belt 333 and is transferred to the image forming units 317 to 320 by M.
A toner image is formed on the surface in the order of CYK. The sheet or the like that has passed through the K image forming unit 320 is transferred to the transfer belt 33.
In order to facilitate separation from the transfer belt 3, the charge is removed by the discharge charger 349 and then separated from the transfer belt 333. 350
Is a peeling charger, which prevents image disturbance due to peeling discharge when a sheet or the like is separated from the transfer belt 333. The separated sheets and the like have pre-fixing chargers 351 and 352 in order to supplement the toner suction force and prevent image disturbance.
The toner image is thermally fixed by the fixing device 334, and then discharged to the discharge tray 335.

FIG. 2 is a block diagram showing the detailed arrangement of the printer processing section. LED image recording will be described with reference to FIG. Binary C generated by the image processing unit in FIG.
The MYK image signal is generated by the binary conversion unit based on the sheet leading edge signal from the sheet leading edge sensor 347, and the delay units 202 to 205 adjust the difference in distance between the sheet leading edge sensor and each image forming unit. By doing so, it becomes possible to print four colors at predetermined positions. LE
The D drives 206 to 209 generate signals for driving the LEDs 210 to 213.

(Other Embodiments) In this embodiment, the timing for operating the pickup roller is changed based on the type of the sheet, and the interval between the plurality of conveyed sheets is adjusted. The condition for adjusting the interval is not particularly limited to the use of the type of sheet, and a value obtained from an environmental temperature measuring sensor for measuring temperature or humidity may be used instead. Good.

FIG. 8 shows a procedure for adjusting the interval on the basis of these measured values. In this case, temperature and humidity information is acquired from the environment measurement sensor, and if the environment temperature and humidity are above the threshold value, it is determined that the sheet is in a condition in which it is likely to curl, and the feeding timing is set to a long In the following cases, the feeding timing is set shorter.

Further, in this embodiment, in order to adjust the interval between a plurality of sheets to be conveyed, a means for changing the timing at which the pickup roller is operated is used. As means for adjusting this interval, Between the speed V ₁ for feeding the sheet from the sheet stacking portion and the speed V ₂ for conveying the sheet, the number of rotations of the pickup roller and the registration roller is always kept high, and a relationship of V ₁ > V ₂ is established. It is also possible to adjust the distance between the sheets.

[0040]

As described above, according to the present invention,
When the type of sheet is plain paper or when the environmental humidity is low, the sheet is fed to the image forming unit while keeping the interval between multiple sheets to be conveyed to the required minimum by changing the paper feed timing. The number of continuous image formation is increased, and the life of the image forming unit is not wastefully consumed by the sheet interval region, so that the running cost is reduced.

Further, according to the present invention, the apparatus automatically determines and adjusts the interval between the sheets. Therefore, it is necessary for the user to adjust the distance between the sheets in consideration of the type of sheet and the environment in which the apparatus is used. There is no.

Further, in the present invention, the interval between the plurality of sheets is adjusted by changing the timing of the operation of the pickup roller or by providing a speed difference between the paper feeding speed and the conveying speed. , The driving source such as a motor for driving the roller does not need to change the speed,
The drive unit does not emit shifting sounds.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital image processing unit.

FIG. 2 is a block diagram showing a configuration of a printer processing unit.

FIG. 3 is a diagram showing an overall configuration of an image forming apparatus.

FIG. 4 is a block diagram showing a configuration of a control unit.

FIG. 5 is a diagram schematically illustrating an example of a state of sheets being double-fed and conveyed.

FIG. 6 is a time chart of each part in the case of continuously feeding sheets at regular intervals (a) and in the case of continuously feeding sheets at a minimum sheet interval (b).

FIG. 7 is a flowchart showing a process for switching the setting of the feeding timing depending on the type of paper.

FIG. 8 is a flowchart showing a process of switching the setting of the feeding timing depending on the environment.

[Explanation of symbols]

101 CCD 102 Clamp & Amp & S / H & A / D 103 Shading section 104 Connection & MTF Correction & Document Detection Unit 105 Input masking section

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 21/14 G03G 21/00 372 F term (reference) 2H027 DA11 DA14 DC02 DE07 ED17 EE07 3F048 AA02 AA05 AB01 BA05 BB02 CA02 CA03 CA04 CB04 CC03 CC04 DA04 DA06 DB07 3F049 AA05 AA10 CA01 DA12 EA23 LA02 LA06 LA07 LB03 3F101 LA02 LA06 LA07 LB03 3F343 FA01 FB02 FB05 FC19 GA01 GB01 GC01 GD01 JA01 KB05 KB06 LA04 LA16 LB08 LC03 LC09 LD14 MB28 MA36 MA14 MA27 MA36 MA14 MA27 MA15 MA36

Claims (18)

[Claims] 1. A sheet feeding device having a sheet stacking unit and a sheet transporting path, capable of feeding and transporting a plurality of sheets stacked on the stacking unit, the sheet being stacked on the stacking unit. A means for feeding the sheets from the stacking section, a means for adjusting the distance between the sheets when the plurality of sheets are conveyed, and a means for conveying the plurality of sheets while maintaining the adjusted distance. A sheet feeding device, which has the adjustment of the sheet interval automatically based on a condition. 2. Particularly, in a means for feeding from a sheet stacking section, a sheet feeding section for feeding a sheet from the stacking section by pressing a pickup roller against the sheet stored in the stacking section, and the sheet is fed. In the means to adjust the distance between the sheets,
2. The sheet feeding apparatus according to claim 1, further comprising: a unit that adjusts a sheet interval by adjusting a timing of pressing the pickup roller against the sheet. 3. A relationship of V ₁ > V ₂ between a speed V ₁ for feeding a sheet from a sheet stacking section and a sheet conveying speed V ₂ and means for adjusting a distance between conveyed sheets, 2. The sheet feeding device according to claim 1, further comprising: a unit configured to adjust a sheet interval by adjusting a timing of feeding the sheet from the sheet stacking unit. 4. A means for sensing a device environment such as temperature and humidity, and in particular, the device environment is adopted as a sheet interval determination condition used when executing the adjustment of the sheet interval. The sheet feeding device according to claim 1. 5. A means for storing the type of sheets stacked on the sheet stacking unit, and in particular, the sheet type is set as a sheet interval determination condition used when executing the adjustment of the sheet interval. The sheet feeding device according to claim 1, which is employed. 6. A means for sensing a device environment such as temperature and humidity, and in particular, the device environment is adopted as a sheet interval determination condition used when executing the adjustment of the sheet interval. The sheet feeding device according to claim 2. 7. A means for storing the type of sheets stacked on the sheet stacking unit, and in particular, the sheet type is set as a sheet interval determination condition used when the adjustment of the sheet interval is performed. The sheet feeding device according to claim 2, which is employed. 8. A means for sensing a device environment such as temperature and humidity, and in particular, the device environment is adopted as a sheet interval determination condition used when the adjustment of the sheet interval is performed. The sheet feeding device according to claim 3. 9. A unit for storing the type of sheets stacked on the sheet stacking unit, and in particular, the sheet type is set as a sheet interval determination condition used when executing the adjustment of the sheet interval. The sheet feeding device according to claim 3, wherein the sheet feeding device is employed. 10. A sheet stacking unit and a sheet conveying path are provided,
In a sheet feeding device capable of feeding and transporting a plurality of sheets stacked on the stacking unit, a unit for feeding the sheets stacked on the stacking unit from the stacking unit, and a method of transporting the plurality of sheets. And a means for conveying the trailing edge of the preceding sheet and the leading edge of the succeeding sheet to the preceding sheet, and a means for conveying a plurality of sheets while maintaining the superposed state. A sheet feeding apparatus, which has, when a sheet is conveyed, automatically determining whether or not to overlap the sheets based on a condition. 11. Particularly, in a means for feeding from a sheet stacking section, a sheet feeding section for feeding a sheet from the stacking section by pressing a pickup roller against the sheet stored in the stacking section, and the sheet is fed. 11. The sheet feeding apparatus according to claim 10, further comprising: a means for superposing the sheets, the means for superposing the sheets by adjusting a timing at which the pickup roller is pressed against the sheets. 12. A relationship of V ₁ > V ₂ between a speed V ₁ for feeding a sheet from a sheet stacking section and a sheet conveying speed V ₂ and means for superposing sheets to be conveyed, A means for superposing the sheets by adjusting the timing of feeding the sheets from the stacking section,
The sheet feeding device according to claim 10, further comprising: 13. A device for sensing a device environment such as temperature and humidity, and in particular, the device environment is adopted as a determination condition used when determining whether or not sheets are to be stacked and conveyed. The sheet feeding device according to claim 10, wherein: 14. A unit for storing the type of sheets stacked on the sheet stacking unit, and in particular, as a determination condition used when determining whether or not to convey the sheets in an overlapping manner, The sheet feeding device according to claim 10, wherein the sheet type is adopted. 15. A device for sensing the device environment such as temperature and humidity, and in particular, adopts the device environment as a determination condition to be used when determining whether or not sheets are to be stacked and conveyed. The sheet feeding device according to claim 11, wherein: 16. A means for storing the type of sheets stacked in the sheet stacking section, and in particular, as a determination condition used when determining whether or not to convey the sheets in an overlapping manner, The sheet feeding device according to claim 11, wherein the sheet type is adopted. 17. A device for sensing a device environment such as temperature and humidity, and in particular, the device environment is adopted as a determination condition to be used when determining whether or not the sheets are stacked and conveyed. The sheet feeding device according to claim 12, wherein 18. A unit for storing the type of sheets stacked on the sheet stacking unit, and in particular, as a determination condition used when determining whether or not to convey the sheets in an overlapping manner, 13. The sheet feeding apparatus according to claim 12, wherein the sheet type is adopted.