Patent Application
20050133980
1. Field of the Invention
The present invention relates to a sheet feeding apparatus for separating and feeding the uppermost sheet of a sheet stack, in particular, it relates to a sheet feeding apparatus to be used for an image forming apparatus such as a copying machine, a printer and a facsimile equipment.
2. Description of the Related Art
Conventionally, according to the image forming apparatus such as a copying machine and a printer, cut sheet to be fed continuously have been limited to in general good quality paper or plain paper designated by the copying machine manufacturer. Since the sheets have a low surface smoothness and a low air permeability, air can easily be introduced between the sheets. Therefore, sticking of the sheets and generation of superimposition can hardly be generated at the time of taking out the sheets one by one from the stacked sheets.
However, recently, according to the variation of the recording media, in addition to the thick papers, the OHP papers, the tracing papers, or the like, from the demand for the colors from the market, image formation on the sheets having a smooth surface such as art papers, coat papers, with a coating process applied on the sheet surface for providing the whiteness and the glossiness has been more and more required. However, since the OHP papers, the tracing papers, the art papers, the coat papers, or the like have a high smoothness and a high air permeability, particularly in the case of piling the above-mentioned sheets in a high humidity environment, the sheets stick with each other. In the case the sheets stick with each other, a problem is involved in that superimposition and feeding error are generated frequently according to the friction separation method commonly used in the conventional image forming apparatus such as a copying machine and a printer.
On the other hand, those of the air feeding method of separating and feeding one by one from the upper sheet by a vacuuming device and a feeding belt disposed above while separating a sheet bundle by blowing the air from the side surface of a sheet stack supported and stored in an image forming apparatus at the same time have been adopted in the printing industry and a part of the copying machines, or the like. According to the air feeding method, compared with the friction separation method, there are advantages such as (1) a wide setting latitude of the feeding conditions with respect to various sheets of different materials, (2) capability of high speed feeding, (3) a high durability, and (4) a low running cost.
A number of proposals have been given for the air feeding. For example, a paper feeding apparatus disclosed for example in the official gazette of the Japanese Patent Application Laid Open (JP-A) No. 62-249835 can be presented. According to the paper feeding apparatus, a method of blowing the air in the direction parallel to the sheet upper surface by an air blowing device onto the sheet top end side surface supported on a paper feeding stand and at the same time having the vacuuming cylinder opened above the sheets in a negative pressure by a negative pressure generating device for vacuuming is proposed. According to the paper feeding apparatus, the sheets are separated by lifting the uppermost sheets from the sheets stacked on the paper feeding stand by the vacuuming function from the opening and blowing the air from the air blowing device into the gap formed between the uppermost sheet and the next sheet.
However, as mentioned above, since the sheets of the OHP papers, the tracing papers, the art papers, the coat papers, or the like have a high smoothness and a high air permeability, particularly in the case the sheets are stacked in a high humidity environment, the sheets stick with each other. Here, in the case the air feeding method is adopted, since the air blown from the side surface of the sheet bundle is a constant flow, the sheet bundle in the upper part may be lifted on the sheet bundle in the lower part out of the sheet bundle at the interface of the sheets with a relatively weak sticking force. Therefore, the sheet bundle in the upper part lifted on the sheet bundle in the lower part cannot have the air introduction between the sheets (gaps) in the sheet bundle so that it has been extremely difficult to certainly separate the uppermost sheet one by one.
The present invention has been achieved in view of the above-mentioned problems, and an object thereof is to provide a sheet feeding apparatus capable of certainly releasing sticking of the sheets in a simple configuration for preventing generation of the feeding error or the superimposition in the air feeding method, which is superior in terms of the compatibility to the sheet materials, the high speed feeding, the high durability, or the like. Furthermore, it is to improve the miniaturization of the apparatus, reduction of the product cost and the running cost, and the reliability.
In order to achieve the above-mentioned object, the present invention provides a sheet feeding apparatus comprising:
Moreover, the present invention provides a sheet feeding apparatus comprising:
Hereinafter, with reference to the drawings, preferable embodiments of the present invention will be explained in detail. However, the size of the component parts, the material, the shape, the relative arrangement thereof, or the like disclosed in the following embodiments can optionally be changed according to the configuration and the various conditions of an apparatus with the present invention applied, and thus the scope of the present invention is not limited thereby.
(Entire Configuration)
As shown in
A can store 1,000 sheets and the paper deck 401B can store 1,500 sheets, and the paper decks 40A, 40B have the same configuration. The sheet feeding part 40 will be explained later in detail.
A document feeding device 10 is mounted in the image reader 20. The document feeding device 10 feeds a document with the image surface set upward on a document tray 11 one by one from the top page in the leftward direction in the figure via a curved path on a platen glass 12 from the left side to the rightward direction through a flow reading position, and then discharges the same onto an outside discharging tray 13. At the time the document passes the flow reading position on the platen glass 12 from the left side to the right side, the document image is read out by a scanner unit 21 supported at a position corresponding to the flow reading position. The reading method is a method in general called the document flow reading. Specifically, at the time the document passes by the flow reading position, the document reading surface is irradiated by the light beam of a lamp 22 of the scanner unit 21 so that the light beam reflected from the document is guided to a lens 26 via mirror 23, 24, 25. The light beam passes through the lens 26 is focused onto an imaging surface of an image sensor 27.
Accordingly, by feeding the document from the left side to the right side so that it passes by the flow reading position, a document reading scan with the direction perpendicular to the document feeding direction provided as the main scanning direction and the feeding direction provided as the sub scanning direction is executed. That is, by feeding the document in the sub scanning direction while reading the document image per each line in the main scanning direction by the image sensor 27 at the time of having the document pass by the flow reading position, the entire document image is read out so that the image optically read out is converted to an image data by the image sensor 27 so as to be outputted. The image data outputted from the image sensor 27 are inputted to an exposure control part 30A of the printer 30 as a video signal after applying a predetermined process at an unshown image signal control part.
It is also possible to read out the document by scanning with the scanner unit 21 from the left side to the right side in a state with the document fed onto the platen glass 12 by the document feeding device 10 so as to be stopped at a predetermined position. The reading method is a method so called the document fixed reading.
In the case of reading the document without using the document feeding device 10, first, the document feeding device 10 is opened and closed by a user for placing the document onto the platen glass 12. Then, the document is read out by scanning with the scanner unit 21 from the left side to the right side. That is, at the time of reading out the document without using the document feeding device 10, the document fixing reading is executed.
The exposure control part 30A of the printer 30 modulates and outputs a laser beam based on the inputted video signal so that the laser beam is directed onto a photosensitive drum 31 while being scanned by a polygon mirror. An electrostatic latent image is formed on the photosensitive drum 31 according to the scanned laser beam. Here, the exposure control part 30A outputs a laser beam so as to form a correct image (an image, which is not a mirror image) at the time of the document fixing reading.
The electrostatic latent image on the photosensitive drum 31 is visualized as a developing agent image by a developing agent supplied from an unshown developer. Moreover, a sheet is fed selectively from the paper decks 40A, 40B as the sheet feeding device to be described later at a timing synchronously with the start of the laser beam irradiation so that the sheet is fed between the photosensitive drum 31 and a transfer part 33 by a resist roller pair 32. The developing agent image formed on the photosensitive drum 31 is transferred onto the sheet fed by the transfer part 33.
The sheet with the developing agent image transferred is fed to a fixing part 34 so that the fixing part 34 fixes the developing agent image on the sheet by heating and pressuring the sheet. The sheet passed through the fixing part 34 is discharged onto a first discharging tray 37 via a first discharging roller 36 or onto a second discharging tray 39 via a second discharging roller 38 according to the changeover of a flapper 35.
Next, the paper decks of the air feeding method as the sheet feeding device according to the present invention will be explained in detail with reference to the embodiments. Although the numbers of the sheets to be stored in the paper decks differ, since the other configuration is same, the paper deck 40A will be explained in the following description and the same, numerals are applied to the members having the same function of the paper deck 40B so as to omit the explanation.
A feeding unit 45 as a sheet feeding means for vacuuming and feeding by the air the uppermost sheet of the sheet stack S supported on the above-mentioned middle plate 43 is provided above the sheet stack supported and stored on in the storage bank 41. The feeding unit 45 comprises a vacuuming means 45a capable of generating a vacuuming static pressure, such as a fan and a vacuuming duct 45b. Furthermore, a vacuuming belt 45c comprising a large number of holes, surrounding the vacuuming duct 45b, is provided rotatably in the sheet feeding direction.
Moreover, an air blowing unit 46 as an air blowing means, comprising a duct for blowing the air from the direction substantially perpendicular to the side surface of the upper part of the sheet stack S supported on the above-mentioned middle plate 43 is provided on the top end side of the sheet stack supported and stored in the storage bank 41.
Next, with reference to
In
To the controller, the material and the size of the sheets to be piled on the paper decks 40A, 40B are inputted by an user from an inputting means I. Moreover, the temperature, the humidity, or the like inside and outside the storage bank 41 are inputted form an environment sensor SE. Furthermore, a detection signal of the upper surface of the sheet bundle S is inputted from a first sheet height detecting means 48 and a second sheet height detecting means 49 to be described later. Then, based on the information, the controller C carries out the elevation control of the middle plate 43 by a lift up motor 43a (shown in
Next, the sheet separation feeding operation in the above-mentioned paper deck 40A will be explained in detail. In the case the sheet bundle is set in the storage bank 41 of the paper deck 40A and the paper deck 40A is inserted into the image forming apparatus man body, the middle plate 43 is lifted up by the lift up motor 43a to a pre-separation height (first height) H1 set by a first sheet height detecting means 48 (see
The number of the reciprocal motion and the moving speed of the shutter 47a in the above-mentioned pre-separation operation can be set optionally by the material and the size of the sheet, and the environmental conditions. Here, the present inventor collected the sticking force data between the sheets as to the coat paper to be stuck easily at a high humidity (temperature 30° C./humidity 80%). Results are shown in
Next, as shown in
The timing of the air blowing operation by the above-mentioned air blowing unit 46 to be carried out while reciprocally moving the shutter 47a having the above-mentioned slit 47b is not limited to the pre-separation operation at the first position but also it can be operated while the uppermost surface of the above-mentioned sheet bundle is moved between the above-mentioned first position H1 and the above-mentioned second position H2 or it is at the second position H2. That is, the air blowing operation can be carried out by the above-mentioned air blowing unit 46 while reciprocally moving the shutter 47a having the above-mentioned slit 47b during the sheet feeding operation after the above-mentioned pre-separation operation.
As heretofore explained, according to this embodiment, since the pre-separation height (first position) H1 is set in the reciprocal movement range of the slit 47b of the shutter 47 having a high sheet separation effect (in the range of the vertical direction width of the duct opening 46a) and the sheet bundle separated sufficiently is moved to the feeding sheet surface height (second position) H2 above the pre-separation height H1 for vacuuming and feeding the sheets, even in the case of a bundle of special sheets such as a coat paper of a material different from a plain paper, or the like, that is, a bundle of sheets having a relatively high sticking force between the sheets, the stickiness can be released by certainly introducing the air between the sheets. Thereby, according to the air feeding method superior in terms of the compatibility to the sheet materials, the high speed feeding, the high durability or the like, a sheet feeding apparatus capable of certainly releasing the stickiness between the sheets in a simple configuration and preventing generation of the feeding error and the superimposition can be provided.
Furthermore, since it has a simple configuration of executing the pre-separation operation by the blowing air of the air blowing unit 46 at the first position H1 with the uppermost surface of the sheet stack in the vertical direction width range of the duct opening 46a and the vacuuming feeding operation by the feeding unit 45 at the second position H2 above the first position H1, the sheets can be separated and fed certainly in a simple configuration without the need of additionally providing new parts of the bulkiness of the apparatus, or increasing the parts cost or the running cost so as to improve the reliability.
Although the case of having the initial position of the shutter 47a at the uppermost position in the moving direction has been explained above, it is not limited thereto and thus it can be provided at an optional position. Moreover, the vacuuming means 45a or the unshown blowing fan may be a fan such as a sirocco fan, a compressor, or the like.
Moreover, in order to further improve the separation effect during continuous feeding according to the conditions such as the environment and the material, it is also possible to provide the control of temporarily stopping the sheet feeding operation even in the case there is a remaining feeding job at the time of a continuous feeding job of a certain number or more sheets, moving the uppermost surface of the sheet stack from the feeding sheet surface height H2 to the pre-separation height H1 by lowering the middle plate 43, and again lifting the same up to the feeding sheet surface height H2 after executing the pre-separation operation so as to execute the remaining feeding job.
The second embodiment of the present invention will be explained with reference to
This embodiment comprises a swing nozzle 47d capable of rotating the sheet bundle upper side end part in the vertical direction in the blowing duct 46b provided on the sheet bundle top end side. The swing nozzle 47d is an air direction varying means for changing the orientation of the air blown out from the air blowing unit 46 such as a blowing fan, which executes the pre-separation operation for the sheet bundle lifted up to the pre-separation height (first position) H1 as in the first embodiment. The above-mentioned swing nozzle 47d blows the air to the sheet bundle side surface while changing the orientation thereof from the initial position (upward) shown in
After executing the above-mentioned pre-separation operation, like the above-mentioned first embodiment, as shown in
The timing of the air blowing operation by the above-mentioned air blowing unit 46 to be carried out while rotating the above-mentioned swing nozzle 47d is not limited to the pre-separation operation, but also it can be operated while at least the uppermost surface of the above-mentioned sheet bundle is between the above-mentioned first position H1 and the above-mentioned second position H2. That is, the air blowing operation can be carried out by the above-mentioned air blowing unit 46 while rotating the swing nozzle 47d during the sheet feeding operation after the above-mentioned pre-separation operation.
As heretofore explained, also according to this embodiment, since the pre-separation height (first position) H1 is set in the duct swing operation range of the swing nozzle 47d having a high sheet separation effect (in the range of the vertical direction width of the duct opening 46a) and the sheet bundle separated sufficiently is moved to the feeding sheet surface height (second position) H2 above the pre-separation height H1 for vacuuming and feeding the sheets, even in the case of a bundle of special sheets such as a coat paper of a material different from a plain paper, or the like, that is, a bundle of sheets having a relatively high sticking force between the sheets, the stickiness can be released by certainly introducing the air between the sheets. Thereby, according to the air feeding method superior in terms of the compatibility to the sheet materials, the high speed feeding, the high durability, or the like, a sheet feeding apparatus capable of certainly releasing the stickiness between the sheets in a simple configuration and preventing generation of the feeding error and the superimposition can be provided.
Furthermore, since it has a simple configuration of executing the pre-separation operation by the blowing air of the air blowing unit 46 at the first position H1 with the uppermost surface of the sheet stack in the vertical direction width range of the duct opening 46a and the vacuuming feeding operation by the feeding unit 45 at the second position H2 above the first position H1, the sheets can be separated and fed certainly in a simple configuration without the need of additionally providing new parts of the bulkiness of the apparatus, or increasing the parts cost or the running cost so as to improve the reliability.
Although the case of having the initial position of the swing nozzle 47d at the uppermost position (upward) in the moving direction has been explained above, it is not Limited thereto and thus it can be provided at an optional position. Moreover, the vacuuming means 45a or the unshown blowing fan may be a fan such as a sirocco fan, a compressor, or the like.
Moreover, in order to further improve the separation effect during continuous feeding according to the conditions such as the environment and the material, it is also possible to provide the control of temporarily stopping the sheet feeding operation even in the case there is a remaining feeding job at the time of a continuous feeding job of a certain number or more sheets, moving the uppermost surface of the sheet stack from the feeding sheet surface height H2 to the pre-separation height H1 by lowering the middle plate 43, and again lifting the same up to the feeding sheet surface height H2 after executing the pre-separation operation so as to execute the remaining feeding job.
Although an example of the shutter (channel moving means) 47a having the slit 47b in a part has been explained as the air blowing speed varying means for changing the air blowing speed to be blown out from the air blowing means in the above-mentioned embodiment, it is not limited thereto. For example, one having the air supplied from the air supply source of the blowing air increased or reduced by the on/off changeover, or an air blocking means capable of blocking or opening the air channel provided inside the blowing duct opening 46a can be adopted as well. In any case, by setting the pre-separation height (first position) H1 in the opening width (in the vertical direction width range) of the blowing duct opening 46a for executing the pre-separation operation thereat, the sheets can be separated certainly at the feeding sheet surface height (second position) H2 above the pre-separation height.
Moreover, although the cases of providing the positions of the blowing duct 46b and the shutter 47a, the positions of the blowing duct 46b and the swing nozzle 47d at the sheet bundle side surface top end part have been explained in the above-mentioned embodiments, it is not limited thereto, and an optional position at the sheet bundle side surface can be used as well.
Furthermore, although the configuration of providing the air blowing means only at the sheet bundle side surface top end part has been explained, it is not limited thereto, and as needed, it can be disposed at a plurality of points facing the sheet bundle side surface. Moreover, it is also possible to use in a combination with the air blowing speed varying means or the air pressure varying means explained in the above-mentioned first and second embodiments.
Moreover, although the example of the sheet feeding apparatus having only the air feeding method ha been explained as the sheet feeding mechanism for separating and feeding the sheets, a configuration having another separating means can be adopted as well.
Furthermore, although the case of a copying machine has been explained as the image forming apparatus in the above-mentioned embodiments, the present invention is not limited thereto, and for example, another image forming apparatus such as a scanner, a printer and a facsimile equipment, another image forming apparatus such as a composite machine combining the functions thereof, an image forming apparatus using a transfer material supporting member for successively superimposing and transferring toner images of various colors onto a transfer material supported by the transfer material supporting member, or an image forming apparatus using an intermediate transfer member, successively superimposing and transferring toner images of various colors onto the intermediate transfer member, and transferring the toner images supported by the intermediate transfer member onto a transfer material collectively may be adopted as well. By adopting the present invention to the sheet feeding apparatus used in the image forming apparatus, the same effect can be obtained.
Moreover, although the example of the sheet feeding apparatus provided integrally in the image forming apparatus has been explained in the above-mentioned embodiments, the present invention is not limited thereto, and by adopting the present invention to the sheet feeding apparatus, the same effect can be obtained.
Furthermore, although the example of the sheet feeding apparatus for separating and feeding the sheets of a plain paper, a coat paper, or the like as the recording subject has been explained in the above-mentioned embodiments, the present invention is not limited thereto. For example, by adopting the present invention to the sheet feeding apparatus for feeding the documents (sheets) of a plain paper, an OHP paper, or the like as the reading subject to an image reading part, the same effect can be obtained.
Moreover, although the example of the electron photography method has been explained as the recording method in the above-mentioned embodiments, it is not limited thereto. For example, another recording method such as an ink jet method can be used as well.
This application claims priority from Japanese Patent Application No. 2003-407026 filed Dec. 5, 2003, which is hereby incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-407026 | Dec 2003 | JP | national |
