JP3854223B2 - Paper feeder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper feeding device installed in a copying machine, a facsimile, a printer, and the like.
[0002]
[Prior art]
A typical example (for example, see Permitted Document 1) of sequentially feeding the sheets stored in the cassette from the uppermost sheet will be described with reference to FIG. FIG. 7A shows a state where the paper is fully accommodated, and FIG. 7B shows a state where the remaining amount of paper is almost exhausted.
[0003]
In this cassette apparatus, a bottom plate 6 on which a sheet P is placed on a cassette body 4 is attached around a swing center 5 so as to be swingable up and down, and between the bottom plate 6 and the bottom wall 4 a of the cassette body 4, A spring (not shown) that pushes up 6 is provided, and the top surface of the top end of the paper P is pressed against the feed roller 8.
[0004]
Then, by rotating the delivery roller 8, the placed paper P is sequentially delivered from the uppermost paper in the delivery direction indicated by the arrow Y. The remaining paper P is pushed up by the bottom plate 6, and the paper located at the top is always kept pressed against the delivery roller 8. The sheet sent out by the sending roller 8 is conveyed through a pair of paper feed rollers 10a and 10b. For example, in a copying machine using an electrostatic latent image, a pair of registration rollers that perform registration of the paper. (Not shown) and then to a photosensitive drum (not shown).
[0005]
Due to the structure of the sheet feeding device as described above, a deviation occurs in the timing of sheet feeding. That is, in the state where the paper P shown in FIG. 7A is full and the state where the remaining amount shown in FIG. The position changes to the upstream position X2 when the number of sheets is large, and to the downstream position X1 when the number of sheets is small.
[0006]
When the leading edge position of the sheet to be sent out changes as described above, the time for moving the sheet from a feeding start operation for operating the feeding roller 8 to a predetermined section, for example, the nip entrance position of the registration roller, differs depending on the remaining amount of the sheet. End up. As a result, when the remaining amount of paper on the bottom plate decreases, the above-described deviation increases, and a phenomenon may occur in which the image on the paper deviates from the target position on the rear end side in the paper transport direction.
[0007]
In the conventional monochrome machine, it is possible to prevent the position of the leading edge of the image on the paper from being shifted by starting the formation of the image on the photosensitive member after the paper reaches the nip position of the registration roller. . However, in color machines that have been actively developed in recent years, particularly in the type in which an image primarily transferred onto an intermediate transfer belt is secondarily transferred onto a sheet, image formation is started before the conveyance of the sheet is started. If it is delayed, the leading edge of the image on the sheet is shifted as it is (the position of the image is shifted from the normal position downstream in the sheet conveyance direction). For example, when the length direction of A4 paper is the paper transport direction, the leading edge of the image is shifted by about 10 mm on the last paper of 500 sheets of 75 g paper. This deviation increases as the total thickness (thickness x number of sheets) of paper that can be stored in the paper feed cassette increases.
[0008]
As a method of improving such a paper feeding failure state, for example, the bottom plate on which the paper is placed is moved up and down substantially in parallel with the bottom wall of the cassette body without swinging, and the leading edge of the paper has the remaining amount of paper. A structure is adopted that always remains the same even if it changes (see, for example, Patent Document 2). However, this method complicates the cassette device and requires a bottom plate having a size corresponding to the size of the paper, which raises the problem of cost increase.
[0009]
[Patent Document 1]
JP-A-5-330673 (FIGS. 1 and 6)
[Patent Document 2]
JP 2001-88950 A (FIG. 4)
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned facts, and its technical problem is that even when the remaining amount of paper stored in the cassette changes and the leading end position in the paper feeding direction changes, the paper can be fed to the supply destination without delay. It is an object of the present invention to provide a paper feeding device that can feed stably and can prevent the structure of the cassette device from becoming complicated.
[0010]
[Means for Solving the Invention]
In the present invention, as a paper feeding device that solves the above technical problem, the end of the paper feeding side is attached to the cassette body of the paper feeding cassette so as to be swingable up and down and elastically biased upward. The sheet placed on the bottom plate in order from the top, and a feeding roller having a circular cross section disposed on the sheet feeding side of the cassette body feeds the sheet to the sheet feeding roller. In a color printing paper feeder where the leading edge of the paper shifts backward with respect to the paper feeding direction when the remaining amount of paper is low, the timing of the paper sent by the feeding roller to the paper feeding roller There is provided a paper feeding device provided with a control means for speeding up according to minutes .
[0011]
In addition, when the leading edge of the paper is behind the feeding direction, the timing of starting the paper feeding is set to be earlier than when the paper is ahead, so that even if the amount of paper changes, it is stably supplied to the paper feeding destination without delay. To be able to. In addition, since the sheet can be stably and stably sent to the supply destination without delay, it is not necessary to complicate the structure of the cassette device.
[0012]
In a preferred embodiment, the control means is provided so as to be swingable about an axis provided above the cassette body, and the leading end is elastically biased to the upper surface of the rear end side of the uppermost portion of the paper. The interlocking member includes a lever extending from the axis toward the upper surface of the paper, and a light shielding plate formed integrally with the lever and extending on the opposite side of the axis, and is configured by an optical switch, and the position of the light shielding plate is determined. The first sensor and the second sensor to be detected are arranged at intervals in the direction in which the light shielding plate swings.
[0013]
By providing the cassette body with a bottom plate having a simple structure, the structure of the paper feeding device can be prevented from becoming complicated.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a paper feeding device configured according to the present invention will be described in more detail with reference to the accompanying drawings illustrating a preferred embodiment. In addition, the substantially same part as FIG. 7 is shown with the same code | symbol.
[0015]
This will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing an outline of the configuration of a paper feeding device generally indicated by numeral 12, and FIG. 2 is an explanatory diagram showing the flow of paper in a color tandem machine that is an image forming machine equipped with the paper feeding device 12. .
[0016]
The paper feeding device 12 is configured to feed the loaded paper P sequentially from the uppermost paper between the pair of paper feeding rollers 10a and 10b by the feeding roller 8 and to start driving the feeding roller 8. The control means 16 for controlling the timing of the recording paper and the detection means 18 for detecting the remaining amount of the paper P and outputting it to the control means 16 are provided. The control means 16 controls the driving of the delivery roller 8 based on output signals from the process unit 20 and the detection means 18 for forming an image of the image forming machine.
[0017]
The sheet feeding cassette device 14 is a well-known one, and includes a cassette body 4, a bottom plate 6 attached to the bottom wall 4 a of the cassette body 4 so as to be able to swing up and down around a swing center 5, and the bottom plate 6 and the cassette. An urging means (not shown) provided between the bottom wall 4a of the main body 4 and urging the bottom plate 6 in the direction of pushing up, and the above-described feed roller 8 and paper feed rollers 10a and 10b are provided. By rotationally driving the delivery roller 8, the paper P is sequentially sent from the uppermost paper in the delivery direction indicated by the arrow Y, and is sent between the paper feed rollers 10a and 10b. The remaining paper P is pushed up by the bottom plate 6, and the paper located at the top is always kept pressed against the delivery roller 8.
[0018]
In this paper feed cassette device 14, as described with reference to FIG. 7, the leading end position X in the paper feed direction Y is almost full from the state where the paper P shown in FIG. As the oscillating state (indicated by a two-dot chain line) is reached, the paper feed direction Y changes from the downstream side to the upstream side.
[0019]
The detecting means 18 is provided above the cassette body 4 so as to be swingable about the axis 15, and the interlocking member 22 whose tip is elastically biased to the upper surface of the uppermost rear end of the paper P, and the interlocking member And switch means 24 for detecting the swing position of 22.
[0020]
The interlocking member 22 includes a lever 22 a extending from the axis 15 toward the upper surface of the paper P, and a light shielding plate 22 b formed integrally with the lever 22 a and extending to the opposite side of the axis 15. The light shielding plate 22b has a configuration in which, for example, an aluminum tape that reflects light is attached to a resin member. The switch means 24 includes a pair of first sensor 24a and second sensor 24b constituted by optical switches. The first sensor 24a and the second sensor 24b are disposed at an interval in the direction in which the light shielding plate 22b swings. The optical switch is formed of a well-known reflection type, and a light emitter made of an LED (light emitting diode), a light receiver made of a phototransistor, and an amplifier are housed in the same case. When it is interrupted, the reflected light is received and the switch is turned “ON”, and when it is not interrupted, it is turned “OFF”.
[0021]
The light shielding plate 22b, the first sensor 24a, and the second sensor 24b are positioned outside the cassette body 4 in the direction in which the axis 15 extends (direction perpendicular to the paper surface of FIG. 1) so as not to interfere with the paper P. Yes.
[0022]
A description will be given mainly with reference to FIG. The color tandem machine includes four units, a first process unit 20a, a second process unit 20b, a third process unit 20c, and a fourth process unit 20d in a process unit 20 for forming a color image, and each unit is at least photosensitive. A black toner image, a magenta toner image, a cyan toner image, and a yellow toner image, which are sequentially formed, are transferred to an intermediate transfer belt 28 that includes a body 26 and a primary transfer roller 27 and passes between them. The paper P sent by the paper feed rollers 10 a and 10 b is registered by the registration roller 30, sent to the secondary transfer roller 32, and the image on the intermediate transfer belt 28 is transferred to the fixing unit 34.
[0023]
3 and 4, the arrangement of the first sensor 24a and the second sensor 24b of the detection means 18, and the relationship between the remaining amount of paper P in the cassette and the outputs of the first sensor 24a and the second sensor 24b. explain. FIG. 3 shows the movement of the interlocking member 22 and the positional relationship between the first sensor 24a and the second sensor 24b, and FIG. 4 shows the relationship between the remaining amount of paper and the sensor output. In the present embodiment, 500 sheets are stored in the cassette in a state where the paper P is “full”, and the detection means 18 has three levels L, M, and H between “zero” and “full”. The steps are detected as shown below.
[0024]
(1) Level H:
As shown in FIG. 3A, when the remaining amount of paper is “500 to 301”, the first sensor 24a is positioned to be “OFF”, and the second sensor 24b is positioned to be “ON”. "H" is detected.
Note that the remaining amount of paper is described in units of one sheet for the sake of explanation, but the detection means 18 can divide the remaining amount of paper into three stages of H, M, and L, so this number is strictly divided and detected. It doesn't have to be possible.
[0025]
(2) Level M:
As shown in FIG. 3B, when the remaining amount of paper is “300 to 151 sheets”, both the first sensor 24a and the second sensor 24b are positioned so that the output is “ON”. Level M "is detected.
[0026]
(3) Level L:
As shown in FIG. 3C, when the remaining amount of paper is “150 to 0”, the first sensor 24a is positioned to be “ON” and the second sensor 24b is positioned to be “OFF”. L "is detected.
[0027]
(4) Level zero:
As shown in FIG. 3D, when the remaining amount of paper is “0”, both the first sensor 24a and the second sensor 24b are positioned so that the output is “OFF”, and “level 0” shown in FIG. Is detected.
[0028]
The control means 16 will be described with reference to FIG. 5 together with FIG. The control means 16 controls the drive start timing of the delivery roller 8 to the existing control means for controlling the drive of the delivery roller 8 by changing the programming of the paper delivery timing as follows. That is, when the start signal of the first process unit 20a of the process unit 20 is input, the timing of starting the driving of the delivery roller 8 is determined based on the output signal levels from the detection means 18, H, M, and L. The remaining amount of paper is increased as the level decreases from H to L, and control is performed so that the paper is stably sent to the supply destination without delay.
[0029]
According to a study in a typical color tandem machine, timing for starting exposure for forming an electrostatic latent image corresponding to an image on the photosensitive member 26 of the first process unit 22a, which is a start signal of the first process unit 22a. On the other hand, the timing T, which is the time until the feeding start when the delivery roller 8 starts driving, is as shown in FIG.
When the remaining amount of paper is level L, Tl = 11152 ms,
At level M, Tm = 1202 ms,
At level H, Th = 1252 ms,
It was convenient to control the setting. Further, detection of the remaining amount of paper by the detecting means 18 was sufficient in three stages.
[0030]
Next, the control procedure in the control means 16 will be described with reference to FIG.
[0031]
In step S-1, the detection unit 18 detects the remaining amount of the paper P.
[0032]
In step S-2, whether or not the output signal of the detection means 18 is "level 0" is compared. If "level 0", the process proceeds to step S-3, and a request for paper supply is issued by, for example, lighting of a lamp. Return to S-1. If it is not “level 0”, the process proceeds to step S-4.
[0033]
In step S-4, whether or not the output signal of the detecting means 18 is “level L” is compared. If it is “level L”, control of “paper feed timing L” is executed in step S-5, and step S-1 is executed. Return to. If it is not “level L”, the process proceeds to step S-6.
[0034]
In step S-6, whether or not the output signal of the detection means 18 is “level M” is compared. If it is “level M”, control of “paper feed timing M” is executed in step S-7, and step S-1 is executed. Return. If it is not “level M”, the process proceeds to step S-8.
[0035]
In step S-8, it is compared whether or not the output signal of the detecting means 18 is "level H". If it is "level H", control of "paper feed timing H" is executed in step S-9, and the process proceeds to step S-1. Return. If it is not “level H”, the process returns to step S-1.
[0036]
The operation of the sheet feeding device 12 having the above-described configuration will be described mainly with reference to FIG.
[0037]
(1) Stable paper feeding:
In the present invention, when the leading end position in the paper feeding direction Y, which changes according to the remaining amount of the paper P, is behind, control is performed so that the driving start timing of the feeding roller 8 is earlier than when it is forward. Since the control means 16 is provided, even when the remaining amount of the paper P accommodated in the cassette body 4 changes and the leading edge position of the paper changes, the paper can be stably sent to the paper supply destination without delay. In the preferred embodiment, the sheet remaining amount detecting means 18 is provided, and the timing for starting the sheet feeding operation is controlled based on the output thereof, so that a stable sheet feeding operation can be obtained with respect to the change in the remaining sheet amount. Thus, it was possible to remove an image shift of about 15 mm (500 sheets accommodated in a paper feed cassette, paper transport speed of 97 mm / s) in a typical conventional color tandem machine, and a stable image could be obtained.
[0038]
(2) Cost increase is prevented:
In the present invention, the paper feed cassette device 14 does not need to have a complicated structure for moving the paper in parallel up and down. Further, the detection means 18 can be configured by modifying the remaining amount detection means that has been installed conventionally, and the remaining amount detection level of the sheet is sufficient in three stages of H, M, and L. Since it is sufficient to modify the existing control means for controlling the drive, a significant increase in cost can be prevented.
[0039]
As described above, the present invention has been described in detail based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications or corrections may be made within the scope of the present invention, for example, as described below. It is something that can be done.
[0040]
(1) Change in paper leading edge position:
In the present embodiment, there is shown a form in which the leading end position X of the paper sent from the paper feeding cassette device 14 is shifted to the rear, which is the upstream side in the paper sending direction Y when the remaining amount of the paper P decreases. According to the present invention, even when the leading end position of the paper feeding cassette device is shifted to the front of the downstream side in the paper feeding direction when the remaining amount of paper is reduced, the driving start timing of the feeding roller is shifted from the rear as the head is shifted forward. It can be applied by controlling to be slow.
[0041]
(2) Detection means:
In the present embodiment, the remaining amount of the paper P is detected by the detecting means 18 having the interlocking member 22 that contacts the upper surface of the uppermost paper and the switch means 24 for detecting the position thereof. The swing angle of the swing center 5 of the bottom plate 6 may be detected by a potentiometer or the like, or may be detected by a sheet number counter.
[0042]
(3) Switch means:
In the present embodiment, an optical switch is provided as the switch means 24 for detecting the position of the interlocking member 22. However, the switch means may be a limit switch having a mechanical contact.
[0043]
(4) Paper remaining level:
In this embodiment, the remaining paper level is set to three levels of H, M, and L between “full” and “zero”, but it is set to two levels depending on the form of the device equipped with the paper feeding device. Or may be appropriately set in multiple stages.
[0044]
(5) Color tandem machine:
In the present embodiment, the paper feeding device 12 is provided in a color tandem machine, which is a color image forming machine. However, the paper feeding device 12 can also be used in other devices such as a printer and a facsimile provided with the paper feeding device.
[0045]
【The invention's effect】
According to the paper feeding device configured in accordance with the present invention, even when the remaining amount of paper stored in the cassette changes and the leading edge position in the paper feeding direction changes, the paper can be stably fed to the supply destination without delay. There is provided a paper feeding device which can be made and the structure of the cassette device can be kept from becoming complicated.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a configuration of a sheet feeding device configured according to the present invention.
FIG. 2 is an explanatory diagram showing a flow of paper in a color tandem machine provided with the paper feeding device shown in FIG.
FIGS. 3A and 3B are diagrams for explaining the operation of the detection unit, in which FIG. 3A is a remaining sheet level “Level H”, FIG. 3B is a remaining sheet level “Level M”, and FIG. ) Indicates the state of the remaining sheet level “level 0”.
FIG. 4 is a table showing a cassette sheet remaining amount and a sensor output relationship.
FIG. 5 is a table showing a paper feed timing which is a relationship between a paper remaining level and a paper feed start time.
FIG. 6 is a flowchart showing a control procedure by the control means.
FIG. 7 is an explanatory diagram showing a state of movement of the leading end position of the sheet depending on the remaining amount of paper in a conventional sheet feeding device.
[Explanation of symbols]
8: Delivery roller 10a, 10b: Paper feed roller 12: Paper feed device 16: Control means 18: Detection means 20: Process unit 20a: First process unit 22: Interlocking member 24: Switch means 24a: First sensor 24b: First 2 sensors P: paper Y: paper feeding direction

Claims (2)

A bottom plate is attached to the cassette body of the paper feed cassette so that the end on the paper delivery side can swing up and down and elastically biased upward, and the sheets stacked on the bottom plate are placed on the bottom plate. The paper is fed in order from the top, and a circular feed roller with a circular cross-section disposed on the paper feed side of the cassette body feeds the paper to the paper feed roller. In the color printing paper feed device that will shift to the rear side,
A sheet feeding device, comprising: a control unit that accelerates the timing of a sheet fed from a feeding roller to a sheet feeding roller according to a deviation of a leading edge of the sheet . The control means is provided swingably about an axis provided above the cassette body, and provided with an interlocking member whose tip is elastically biased to the upper surface of the rear end side of the uppermost portion of the paper,
The interlocking member includes a lever extending from the axis toward the upper surface of the paper, and a light shielding plate formed integrally with the lever and extending to the opposite side of the axis,
2. The feeding device according to claim 1, wherein the first sensor and the second sensor that are configured by optical switches and that detect the position of the light shielding plate are arranged at an interval in a swinging direction of the light shielding plate. Paper device.

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