JP2014058384A - Paper feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device and an image forming apparatus by which a size of accommodated recording sheets can be determined without using a dedicated sensor.SOLUTION: When recording sheets of A3 size are mounted on and across a main tray 200 and a shift tray 210, raising only the shift tray 210 causes the recording sheets to be raised at a neighboring region to the shift tray 210 in the main tray 200 and makes a distance D2 smaller than a distance D1. On the other hand, when recording sheets of A4 size are mounted, raising only the shift tray 210 does not change the level of a top surface of the recording sheets mounted on the main tray 200 and the distance D2 remains the same as the distance D1. The sheet size is determined by whether the distance changes or not.

Description

  The present invention relates to a sheet feeding device and an image forming apparatus, and more particularly to a technique for determining the size of a recording sheet accommodated in a large capacity sheet feeding cabinet.

  Some image forming apparatuses used for business use include a large capacity cabinet (LCC) to feed a sufficient amount of recording sheets in response to a large amount of printing such as digital printing. . The large-capacity paper feed cabinet includes, for example, two trays (a main tray and a shift tray) that store A4 size recording sheets. When the recording sheets stored in the main tray are used up, they are stored in the shift tray. Feeding is continued by moving the recording sheet being moved to the main tray.

A large-capacity paper feed cabinet provided with two A4 trays can store and feed A3 size recording sheets across both trays in addition to A4 size recording sheets. In such a case, it is necessary to determine the size of the stored recording sheet in order to feed the recording sheet of the designated size.
As a technique for discriminating the size of a recording sheet stored in a large-capacity paper feed cabinet, for example, a dedicated sensor is used to detect whether or not a partition plate for partitioning the recording sheet is attached between two A4 trays. The technique to do is disclosed (for example, refer patent document 1). In this way, it is possible to determine whether the recording sheet accommodated in the large-capacity paper feed cabinet is A4 size or A3 size.

Japanese Patent Laid-Open No. 2002-037466 JP-A-11-240630

However, there is a problem that using a dedicated sensor only for detecting the size of the recording sheet increases the cost of parts and assembly of the image forming apparatus.
The present invention has been made in view of the above-described problems, and is a paper feeding device that can determine the size of a recording sheet stored in a large-capacity paper feeding cabinet without using a dedicated sensor. An object is to provide an image forming apparatus.

  In order to achieve the above object, in the paper feeding device according to the present invention, the first and second trays that can be moved up and down individually are the first size recording sheets placed on the second tray. A sheet feeding device that is detachably mounted on the tray and is capable of placing a recording sheet having a size larger than the first size across the first and second trays. The sensor for measuring the distance to the recording sheet bundle placed on one tray at a portion close to the second tray and the recording sheet placement surfaces of the first and second trays are at the same height. When the distances D1 and D2 are equal with respect to the distance D1 measured by the sensor in the contoured state and the distance D2 measured by the sensor after raising only the second tray from the contoured state. Only raise the first tray When the distance D1, D2 are different, the first, both raising the second tray, characterized in that it and a tray lifting means for the height of the recording sheet top surface to the paper feed position.

  When a recording sheet having a size that can only fit in the first tray is placed, the distance to the recording sheet does not change depending on the height of the second tray. It is sufficient to raise only the first tray. On the other hand, when a recording sheet having a size straddling the first and second trays is placed, the distance to the recording sheet changes depending on the height of the second tray. You should raise them together. Further, the sensor for measuring the distance to the recording sheet is also used for detecting the paper feeding position and detecting the presence or absence of the recording sheet. Accordingly, the size of the recording sheet can be determined and the tray can be moved to the paper feeding position without providing a dedicated sensor.

In this case, the portion close to the second tray refers to the distance D1, when a recording sheet having a size larger than the first size is placed across the first and second trays. It is desirable that the site is such that D2 is detected differently.
In the sheet feeding device according to the present invention, the first and second trays that can be moved up and down individually transfer the first size recording sheet placed on the second tray to the first tray. A sheet feeding device that is provided side by side and is capable of placing a recording sheet having a size larger than the first size across the first and second trays, and is placed on the first tray. The sensor for measuring the distance to the set recording sheet bundle at a portion close to the second tray and the recording sheet placement surface of the first and second trays are at the same height, A distance difference (D2-D1) between the distance D1 measured by the sensor and the distance D2 measured by the sensor after lowering only the first tray from the contoured state is the first tray. The first tray only When the distance difference (D2-D1) is smaller than the descending width of the first tray, the first and second trays are both raised to feed the height of the upper surface of the recording sheet. And a tray raising means for setting the position.

In this case, the portion close to the second tray is a recording sheet having a size larger than the first size when the recording sheet is placed across the first and second trays. It is preferable that the distance difference (D2−D1) is a position where it is detected smaller than the descending width of the first tray.
Specifically, the sensor may be disposed at a position higher than the paper feeding position, and the distance to the upper surface of the recording sheet may be measured as the distance. In this case, if the recording sheet placement surface of the first tray has a recess or a through hole at a position corresponding to the sensor in a plan view, the detection of the sensor with and without the recording sheet is detected. Since the distance changes remarkably, it is possible to accurately detect a recording sheet break.

The sensor may be disposed at a position that is the same as or lower than the placement surface of the first tray, and the distance to the lower surface of the recording sheet may be measured as the distance. good.
Furthermore, it goes without saying that the recording sheets placed on the first tray should be fed out of the apparatus one by one from the top.

  An image forming apparatus according to the present invention includes the sheet feeding device according to the present invention. If it does in this way, the above effects can be acquired.

1 is a diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a diagram illustrating a main configuration of a sheet feeding device 100. FIG. FIG. 2 is a cross-sectional perspective view schematically illustrating the main configuration of the sheet feeding device 100. 6 is a flowchart illustrating a recording sheet size detection procedure. FIG. 6 is a diagram schematically illustrating a state of a recording sheet before and after raising a shift tray. FIG. 6 is a cross-sectional perspective view schematically showing a main configuration of a sheet feeding device according to a modified example in which the reference plate 207 is not used. FIG. 10 is a cross-sectional perspective view schematically illustrating a main configuration of a sheet feeding device according to a modified example for detecting a distance to a lower surface of a recording sheet. 10 is a flowchart for determining the size of a recording sheet in a paper feeding apparatus according to a modification. FIG. 6 is a diagram schematically illustrating a state of a recording sheet before and after raising a shift tray. FIG. 10 is a cross-sectional perspective view schematically illustrating still another configuration of a sheet feeding device according to a modification that detects a distance to the lower surface of a recording sheet. 10 is a flowchart for determining the size of a recording sheet in a paper feeding apparatus according to a modification. FIG. 6 is a diagram schematically illustrating a state of a recording sheet before and after lowering a main tray. 10 is a flowchart for determining the size of a recording sheet in a paper feeding apparatus according to a modification. FIG. 6 is a diagram schematically illustrating a state of a recording sheet before and after lowering a main tray.

Hereinafter, embodiments of a fixing device and an image forming apparatus according to the present invention will be described with reference to the drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to the embodiment of the present invention will be described.
As shown in FIG. 1, the image forming apparatus 1 according to the present embodiment is a so-called tandem color printer apparatus, and includes a paper feed cabinet 100 to 102, an image forming unit 110Y to 110K, an intermediate transfer belt 120, a fixing unit. The apparatus 130, the control part 140, etc. are provided.

  When receiving a print job from another apparatus via a network (not shown) such as a LAN (Local Area Network), the control unit 140 controls the image forming units 110Y to 110K to form toner images. The image forming units 110Y to 110K have the same configuration in order to form toner images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). For this reason, in the drawing, only the components of the image forming unit 110Y are denoted by reference numerals, and the component parts of the image forming units 110M to 110K are omitted. Hereinafter, description will be made by omitting the reference numerals representing the color of the toner image to be formed.

  The image forming unit 110 includes a photosensitive drum 111 that rotates in the direction of arrow A. A charging device 112, an exposure device 113, a developing device 114, and a primary device are arranged on the outer periphery of the photosensitive drum 111 along the direction of arrow A. A transfer roller 115 and a cleaning device 116 are provided. The charging device 112 uniformly charges the outer peripheral surface of the photosensitive drum 111. The exposure device 113 forms an electrostatic latent image on the outer peripheral surface of the photosensitive drum 111 by irradiating laser light having an intensity corresponding to the image data processed according to the conditions specified in the print job.

  The developing device 114 supplies toner to the outer peripheral surface of the photosensitive drum 111 to develop the electrostatic latent image into a toner image. The primary transfer roller 115 sandwiches the intermediate transfer belt 120 together with the photosensitive drum 111, and electrostatically transfers (primary transfer) a toner image carried on the outer peripheral surface of the photosensitive drum 111 onto the intermediate transfer belt 120. To do. The cleaning device 116 collects toner remaining on the outer peripheral surface of the photosensitive drum 111 after the primary transfer, and discharges and discharges the outer peripheral surface of the photosensitive drum 111.

  The intermediate transfer belt 120 is an endless belt, is stretched around a plurality of rollers, and rotates in the direction of arrow B. The intermediate transfer belt 120 sequentially transfers the YMCK color toner images so as to overlap each other, and conveys the obtained color toner image to the secondary transfer nip. In parallel with the above, the recording sheet S designated in the print job is supplied one by one from any of the paper feeding apparatuses 100 to 102 by the pickup unit 104, and two by the paper feeding rollers 105 to 108, the registration roller 109, and the like. It is conveyed to the next transfer nip.

  Each of the paper feeding apparatuses 100 to 102 can accommodate a new recording sheet by pulling out toward the front of the image forming apparatus 1. The image forming apparatus 1 is provided with a sensor (not shown) that detects the insertion / removal state of the paper feeding apparatuses 100 to 102, and the detection signal is input to the control unit 140. Thus, when the paper feeding apparatuses 100 to 102 are once pulled out and then stored in the image forming apparatus 1 again, a tray set is detected. The tray set is also detected when the power is turned on.

  The secondary transfer roller pair 121 includes a pair of rollers sandwiching the intermediate transfer belt 120 and applied with a secondary transfer bias to form a secondary transfer nip. When the recording sheet S passes through the secondary transfer nip, the color toner image carried by the intermediate transfer belt 120 is electrostatically transferred (secondary transfer). The toner remaining on the intermediate transfer belt 120 after the secondary transfer is conveyed to the cleaning device 122 as the intermediate transfer belt 120 rotates. The cleaning device 122 collects and discards the residual toner on the intermediate transfer belt 120.

The color toner image carried on the recording sheet S is melted by the fixing device 130 and pressed onto the recording sheet S. The recording sheet S on which the color toner image is fixed is discharged out of the image forming apparatus 1 by the paper discharge roller 131 and accumulated on the paper discharge tray 132.
The image forming apparatus 1 also includes an operation panel (not shown). Under the control of the control unit 140, the image forming apparatus 1 receives an instruction input from the user of the image forming apparatus 1 and displays information for the user.

[2] Configuration of Paper Feed Device 100 Next, the configuration of the paper feed device 100 will be described.
The paper feeding device 100 is a large-capacity paper feeding cabinet having a so-called tandem paper feeding function, and can accommodate A4 size recording sheets and A3 size recording sheets. The sheet feeding device 100 is slidably disposed along a guide rail provided in the image forming apparatus 1, and can draw a recording sheet therein by being pulled out from the front of the image forming apparatus 1. .

  FIG. 2 is a perspective view illustrating a main configuration of the sheet feeding device 100. FIG. 3 is a cross-sectional perspective view schematically showing the main configuration of the sheet feeding device 100. As shown in FIGS. 2 and 3, the paper feeding device 100 includes a main tray 200 and a shift tray 210, both of which can place an A4 size recording sheet. Further, an A3 size recording sheet can be placed across the main tray 200 and the shift tray 210.

The pickup unit 104 includes a pickup roller 220 and a rolling roller 221. The winding roller 221 includes a torque limiter, separates the recording sheets one by one in order to avoid double feeding of the recording sheets sent out by the pickup roller 220, and sends out only the uppermost one of them.
The main tray 200 is suspended by the elevator wires 201 and 202. The elevator wire 201 is stretched around the support pulley 203, and the elevator wire 202 is stretched around the support pulleys 203 and 204. When the elevator motor 205 winds up the elevator wires 201 and 202, the main tray 200 is raised, and when the elevator wires 201 and 202 are fed out, the main tray 200 is lowered.

  A through hole 206 is provided in the vicinity of the shift tray 210 of the main tray 200, and a reference plate 207 is disposed below the through hole 206 when the main tray 200 is lowered most. A distance measurement sensor 208 is fixedly supported on a support member (not shown) above the through hole 206 in the vertical direction. The distance measurement sensor 208 measures the distance to the top surface of the recording sheet when the recording sheet is placed on the main tray 200, and the distance to the reference plate 207 when the recording sheet is not placed on the main tray 200. Measure.

  The shift tray 210 is suspended by the elevator wires 211 and 212. The elevator wire 211 is stretched around the support pulley 213, and the elevator wire 212 is stretched around the support pulleys 213 and 214. When the take-up pulley 215 winds up the elevator wires 211 and 212, the shift tray 210 is raised, and when the elevator wires 211 and 212 are fed out, the shift tray 210 is lowered. The take-up pulley 215 is rotationally driven by the elevator motor 217 via the electromagnetic clutch 216.

  Further, the elevator motor 217 slides the restriction plate base 231 in the horizontal direction via the drive belt 232. A restriction plate 230 is attached to the restriction plate base 231, and as the restriction plate base 231 slides, the restriction plate 230 also slides in the horizontal direction and is placed on the shift tray 210 and is an A4 size recording sheet. Are transferred onto the main tray 200. Note that a clutch (not shown) is disposed on the drive path from the elevator motor 217 to the restriction plate base 231, and transmits or disconnects the slide drive force by the elevator motor 217.

  The elevator motors 207 and 217, the electromagnetic clutch 216, and the like are driven and controlled by the control unit 140, and a detection signal of the distance measurement sensor 208 is input to the control unit 140. In addition, both the main tray 200 and the shift tray 210 are lowered to the lowest position (bottom position) before the sheet feeding device 100 is pulled out from the image forming apparatus 1. The main tray 200 and the shift tray 210 are also lowered to the bottom position even when the image forming apparatus 1 is powered off. When a tray set is detected when the paper feeding device 100 is stored in the image forming device 1 or the image forming device 1 is powered on, the control is performed as described later.

[3] Recording Sheet Size Detection Procedure Next, a recording sheet size detection procedure according to the present embodiment will be described.
FIG. 4 is a flowchart showing a recording sheet size detection procedure. As shown in FIG. 4, when the tray set is detected (S401: YES), the distance measurement sensor 208 measures the distance D1 to the upper surface of the recording sheet placed on the main tray 200 (S402). If the distance D1 obtained by this measurement is shorter than the distance from the distance measurement sensor 208 to the reference plate 207, it is determined that the recording sheet is placed on the main tray 200 (S403: YES). .

  Further, a mark indicating the upper limit of recording sheets that can be accommodated is attached to the paper feeding device 100. When the recording sheet is accommodated up to this upper limit, the distance from the distance measuring sensor 208 to the upper surface of the recording sheet becomes 2 [cm]. Accordingly, when the distance D1 measured by the distance measurement sensor 208 is less than 2 [cm] (S404: YES), it is determined that there are too many recording sheets placed on the main tray 200. That effect is displayed on the panel (S405), and the process is terminated.

  When the distance D1 is 2 [cm] or more, the shift clutch 210 is raised by 2 [cm] by connecting the electromagnetic clutch 216 and rotationally driving the elevator motor 217 (S406). As described above, since there is an interval of 2 [cm] or more from the upper surface of the recording sheet to the distance measuring sensor 208, even if the recording sheet accommodated in the sheet feeding device 100 is A3 size, There is no possibility that the recording sheet collides with the distance measuring sensor 208 due to the rise.

After the shift tray is lifted, the distance measurement sensor 208 again measures the distance D2 to the upper surface of the recording sheet (S407).
As shown in FIG. 5, when only the shift tray 210 is raised when an A3 size recording sheet is placed across the main tray 200 and the shift tray 210, the main tray 200 reaches the vicinity of the shift tray 210. The recording sheet is lifted, and the distance D2 becomes smaller than the distance D1. On the other hand, when an A4 size recording sheet is placed, the height of the upper surface of the recording sheet placed on the main tray 200 does not change even if only the shift tray 210 is raised, so the distance D2 Is equal to the distance D1.

  Thus, if the distance D2 is less than the distance D1 (S408: YES), it is determined that an A3 size recording sheet is placed, and the main tray 200 is used to feed the A3 size recording sheet. Therefore, first, the elevator motor 207 is rotationally driven to raise the main tray 200 by 2 [cm] (S409).

  When the heights of the main tray 200 and the shift tray 210 are aligned, the elevator motors 207 and 217 are simultaneously rotated to drive the main tray 200 and the shift tray 210 simultaneously (S410), and the distance to the upper surface of the recording sheet is set. Measurement is performed by the distance measurement sensor 208 (S411). If the distance to the upper surface of the recording sheet is greater than 0 [cm] (S412: YES), the main tray 200 and the shift tray 210 are continuously raised. When the distance becomes 0 [cm] (S412: NO), the rotation of the elevator motors 207 and 217 is stopped, the electromagnetic clutch 216 is disconnected, and the elevation of the main tray 200 and the shift tray 210 is stopped (S413). The process is terminated.

  When the distance D2 is equal to the distance D1 (S408: NO), it is difficult to determine that an A3 size recording sheet is placed across the main tray 200 and the shift tray 21, and at least the A4 size is placed on the main tray 200. It is determined that the recording sheet is placed. In this case, since only the main tray 200 needs to be raised, first, the elevator motor 217 is rotationally driven to lower the shift tray 210 by 2 [cm], and the electromagnetic clutch 216 is disconnected (S414).

  When the shift tray 210 is stopped at the bottom position, the elevator motor 207 is rotationally driven to raise the main tray 200 (S415), and the distance measurement sensor 208 measures the distance to the upper surface of the recording sheet (S416). . If the distance to the upper surface of the recording sheet is greater than 0 [cm] (S417: YES), the main tray 200 is continuously raised. When the distance reaches 0 [cm] (S417: NO), the rotation of the elevator motor 207 is stopped, the ascent of the main tray 200 is stopped (S418), and the process is terminated.

  If the distance measured in step S402 is equal to the distance to the reference plate 207, it is determined that the recording sheet is not placed on the main tray 200 (S403: YES), so that it is placed on the shift tray 210. In order to transfer the recording sheet on the main tray 200, the elevator motor 217 is rotationally driven to shift the regulating plate 230 (S419). Thereafter, the distance measurement by the distance measurement sensor 208 is performed (S420), and if it is equal to the distance to the reference plate 207, it is determined that the recording sheet is not placed on the main tray 200 (S421: YES). Then, the operation panel informs that the recording sheet has run out (S422), and ends the process. In this case, the processing may be terminated after the main tray 200 is lowered to the bottom position.

If it is determined that the recording sheet is placed on the main tray 200 (S421: NO), the process proceeds to step S416, and the above-described processes from step S415 to step S418 are executed. Also by this processing, the paper feeding device 100 is in a state where the recording sheet on the main tray 200 can be fed, and the processing ends.
In this way, since the distance measuring sensor 208 used for raising the upper surface of the recording sheet placed on the main tray 200 to the paper feeding position is also used for detecting the size of the recording sheet, the size of the recording sheet is detected. There is no need to provide a dedicated sensor for this purpose. Therefore, it is possible to detect the size of the recording sheet without incurring an increase in component costs.

[4] Modifications Although the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .
(1) In the above embodiment, the case where the reference plate 207 is provided below the through hole 206 of the main tray 200 has been described. However, it goes without saying that the present invention is not limited to this, and the following is used instead. Anyway.

  FIG. 6 is a cross-sectional perspective view schematically showing the main configuration of the sheet feeding device according to this modification. The same reference numerals are given to the members corresponding to FIG. As shown in FIG. 6, a concave portion 601 is provided in the main tray 200 provided in the paper feeding device 100 according to this modification instead of the through hole 206. Further, the reference plate 207 is not provided. Therefore, since the number of parts can be further reduced as compared with the above embodiment, the part cost and the assembly cost can be reduced.

  According to this modification, it is possible to detect that no recording sheet is placed on the main tray 200 by the distance measurement sensor 208 measuring the distance to the bottom surface of the recess 601. Moreover, the recessed part 601 has sufficient depth (for example, 1 [cm]). For this reason, since there is a large difference in measurement distance between when there is only one recording sheet on the main tray 200 and when there is no recording sheet, there is no possibility of erroneous detection that there is no recording sheet.

It goes without saying that the size of the recording sheet can be detected by performing the same processing as in the above embodiment.
(2) In the above embodiment, the case where the distance measurement sensor 208 measures the distance from the upper side of the main tray 200 to the upper surface of the recording sheet has been described. Needless to say, the present invention is not limited to this. Instead of this, the following may be used.

As shown in FIG. 7, in the paper feeding device 100 according to this modification, a distance measurement sensor 701 is disposed below the through hole 206 of the main tray 200, and the lower surface of the recording sheet on the main tray 200. The presence or absence of the recording sheet is detected by measuring the distance up to.
FIG. 8 is a flowchart for determining the size of the recording sheet. As shown in FIG. 8, when the tray set is detected (S801: YES), the distance measurement sensor 701 sets the distance D1 to the lower surface of the recording sheet in a state where the main tray 200 and the shift tray 210 are both at the bottom. Measure (S802). If it is determined from the measured distance D1 that the recording sheet is placed on the main tray 200 (S803: NO), the shift tray 200 is moved 2 cm from the bottom position while the main tray 200 is stopped at the bottom position. And the distance measuring sensor 701 measures the distance D2 to the lower surface of the recording sheet (S805).

  As shown in FIG. 9, when an A3 size recording sheet is placed across the main tray 200 and the shift tray 210, the shift tray on the main tray 200 is moved as the shift tray 210 is lifted. The lower surface of the recording sheet is also lifted at a position from 210. Therefore, if the distance D2 is larger than the distance D1 (S806: YES), it is determined that the recording sheet placed is A3 size. In this case, the main tray 200 is raised 2 cm to the same height as the shift tray 210 (S807), and then both the main tray 200 and the shift tray 210 are raised to the paper feed position (S807), and processing is performed. Exit.

  When A4 size recording sheets are placed on each of the main tray 200 and the shift tray 210, the recording sheets on the main tray 200 are not lifted even when the shift tray 210 is raised (FIG. 9). Therefore, if the distances D1 and D2 match (S806: NO), it is determined that the recording sheet placed on the main tray 200 is A4 size. In this case, the shift tray 210 is lowered by 2 cm and returned to the bottom position (S809), the main tray 200 is raised to the paper feed position (S810), and the process is terminated.

  When the recording sheet is not placed on the main tray 200 (S803: YES), the restriction plate 230 is shifted from the shift tray 210 to the main tray 200 (S811), and the distance to the recording sheet is measured again. (S812). If the recording sheet is not yet placed on the main tray 200 (S813: YES), the operation panel notifies that the recording sheet has run out (S814), and the process ends. If a recording sheet is detected on the main tray 200 (S813: NO), the main tray 200 is raised to the paper feed position (S810), and the process is terminated.

Even in this case, the distance measuring sensor 701 for detecting the recording sheet breakage on the main tray 200 is also used for the recording sheet size detection. Therefore, the recording sheet size is detected without using a dedicated sensor. be able to.
In place of the distance measurement sensor 701, a distance measurement sensor 1001 for measuring the distance to the lower surface of the recording sheet placed on the main tray 200 may be disposed in the main tray 200 as shown in FIG. If the same size detection process is performed, the effect of the present invention can be obtained. Further, since the distance measuring sensor 1001 is fixed and supported on the main tray 200, the number of parts can be reduced in the sense that it is not necessary to provide a separate supporting member, and the cost required for materials and assembly can be reduced.

(3) In the above embodiment, the case where the recording sheet on the main tray 200 is displaced by raising the shift tray 210 has been described, but it goes without saying that the present invention is not limited to this. You may do as follows.
The sheet feeding device 100 according to the present modification has substantially the same configuration as that of the sheet feeding device 100 according to the above-described embodiment, while the main tray 200 and the shift tray 210 are replaced with the bottom position when the tray set is detected. The difference is that it stands by at a stand-by position that is 2 cm higher than the bottom position.

  FIG. 11 is a flowchart illustrating a recording sheet size detection procedure according to the present modification. As shown in FIG. 11, when the tray set is detected (S1101: YES), the distance measurement sensor calculates the distance D1 to the upper surface of the recording sheet placed on the main tray 200 at the standby position, as in the above embodiment. Measurement is performed at 208 (S1102). If one or more recording sheets are placed on the main tray 200 as a result of the measurement (S1103: NO), the main tray 200 is lowered by 2 cm from the standby position to the bottom position (S1104), and recording is performed again. The distance D2 to the sheet upper surface is measured (S1105).

  As shown in FIG. 12, when an A3 size recording sheet is placed across the main tray 200 and the shift tray 210, the recording sheet on the main tray 200 is dragged to the shift tray 210 side. The descending width (D2-D1) of the upper surface is less than 2 cm. In such a case (S1106: YES), the main tray 200 is once raised by 2 cm to the standby position (S1107), and then both the main tray 200 and the shift tray 210 are raised to the paper feed position (S1108). ), The process is terminated.

  When the recording sheet placed on the main tray 200 is A4 size, even if the main tray 200 is lowered, the recording sheet on the main tray 200 is not dragged at all, so the descending width (D2-D1) Is equal to 2 cm (FIG. 12). In such a case (S1106: NO), only the main tray 200 is raised to the paper feed position (S1109), and the process ends.

  If it is determined from the measurement result of the distance D1 that the recording sheet is not placed on the main tray 200 (S1103: YES), the main plate 200 is shifted after the restriction plate 230 is shifted (S1110). The distance to the upper surface of the recording sheet is measured (S1111). As a result, if it is determined that there is a recording sheet (S1112: NO), the main tray 200 is raised to the paper feeding position so that the recording sheet can be fed (S1109), and the process is terminated. If it is determined that there is no recording sheet (S1112: YES), the operation panel notifies that the recording sheet has run out (S1113), and the process ends.

Even if size detection is performed according to the above-described procedure, the same effect as in the above embodiment can be obtained.
(4) In the above modification, the case where the size of the recording sheet is detected from the displacement of the lower surface of the recording sheet when the shift tray is raised has been described, but it goes without saying that the present invention is not limited to this. Instead of this, the following may be used.

The paper feeding device 100 according to this modification has a configuration substantially similar to that of the paper feeding device 100 shown in FIG. 7, while the main tray 200 and the shift tray 210 are replaced with the bottom position when the tray set is detected. The difference is that it waits at a standby position that is 2 cm higher than the bottom position.
FIG. 13 is a flowchart illustrating a recording sheet size detection procedure according to the present modification. As shown in FIG. 13, when the tray set is detected (S1301: YES), the distance measurement sensor 1 calculates the distance D1 to the lower surface of the recording sheet placed on the main tray 200 at the standby position, as in the above embodiment. Measurement is performed at 208 (S1302). When one or more recording sheets are placed on the main tray 200 as a result of the measurement (S1303: NO), the main tray 200 is lowered from the standby position to the bottom position by 2 cm (S1304), and recording is performed again. The distance D2 to the lower surface of the sheet is measured (S1305).

  As shown in FIG. 14, when an A3 size recording sheet is placed across the main tray 200 and the shift tray 210, the recording sheet on the main tray 200 is dragged to the shift tray 210 side. The lowering width (D2-D1) of the lower surface is less than 2 cm. In such a case (S1306: YES), the main tray 200 is once raised by 2 cm to the standby position (S1307), and then both the main tray 200 and the shift tray 210 are raised to the paper feed position (S1308). ), The process is terminated.

  When the recording sheet placed on the main tray 200 is A4 size, even if the main tray 200 is lowered, the recording sheet on the main tray 200 is not dragged at all, so the descending width (D2-D1) Is equal to 2 cm (FIG. 12). In such a case (S1306: NO), only the main tray 200 is raised to the paper feed position (S1309), and the process ends.

  If it is determined from the measurement result of the distance D1 that the recording sheet is not placed on the main tray 200 (S1303: YES), the restriction plate 230 is shifted (S1310), and then the main tray 200 is moved. The distance to the lower surface of the recording sheet is measured (S1311). As a result, if it is determined that there is a recording sheet (S1312: NO), the main tray 200 is raised to the sheet feeding position so that the recording sheet can be fed (S1309), and the process is terminated. If it is determined that there is no recording sheet (S1312: YES), the operation panel notifies that the recording sheet has run out (S1313), and the process ends.

Even if size detection is performed according to the above-described procedure, the same effect as in the above embodiment can be obtained.
(5) In the above embodiment, the case where the raising width of the shift tray 210 and the lowering width of the main tray 200 are 2 cm has been described as an example. However, it is needless to say that the present invention is not limited to this value. You may take.

The raising width of the shift tray 210 and the lowering width of the main tray 200 are such that the displacement of the portion of the recording sheet placed on the main tray 200 can be detected when the recording sheet of A3 size is placed. It may be determined according to the Young's modulus of the recording sheet, the attachment position of the distance measurement sensor 208, etc. and the measurement accuracy.
(6) In the above embodiment, both the main tray 200 and the shift tray 210 can place an A4 size recording sheet, and the A3 size recording sheet straddles the main tray 200 and the shift tray 210. However, it is needless to say that the present invention is not limited to this, and recording sheets of other sizes may be placed. For example, both the main tray 200 and the shift tray 210 may be able to place a B5 size recording sheet, and may be able to place a B4 size recording sheet across the main tray 200 and the shift tray 210.

  (7) In the above embodiment, the tandem type color printer apparatus has been described as an example of the image forming apparatus. However, it goes without saying that the present invention is not limited to this, and a color printer other than the tandem type is used instead. The present invention may be applied to an apparatus. Further, the present invention may be applied to a monochrome printer device instead of a color printer device. Furthermore, even if the present invention is applied to a single-function machine such as a copying machine or a facsimile machine equipped with a scanner device or a multi-function peripheral (MFP) having these functions, the same effect can be obtained. it can.

  The sheet feeding device and the image forming apparatus according to the present invention are useful as an apparatus for determining the size of a recording sheet accommodated in a large capacity sheet feeding cabinet.

1 ………………………………………… Image forming apparatuses 100 to 102 ……………………… Paper feeding cabinet 104 ………………………………… Pickup unit 200... ...... Main trays 201, 202, 211, 212 ... Elevate wires 203, 204, 213, 214 ... Support pulleys 205, 217 .................. TOMOTOR 206 ........ Through-hole 207 ................... Reference plate 208, 701, 1001 .......... Distance measuring sensor 210 ......... ………………………… Shift tray 215 ………………………………… Rewinding pulley 216 ………………………………… Electromagnetic clutch 220 ……… ………………………… Pickup roller 221 ……………… ……………………………………………………… Restriction plate 231 …………………………………… Restriction plate base 232 …………………… …………… Drive belt 601 …………………………………… Recess

Claims (9)

First and second trays that can be raised and lowered individually are provided so as to transfer a first size recording sheet placed on the second tray to the first tray, and the first tray A sheet feeding device capable of placing a recording sheet having a size larger than one over the first and second trays;
A sensor for measuring the distance to the recording sheet bundle placed on the first tray at a portion close to the second tray;
A distance D1 measured by the sensor in an equal height state where the recording sheet placement surfaces of the first and second trays are at the same height;
About the distance D2 measured by the sensor after raising only the second tray from the contour level,
If the distances D1, D2 are equal, raise only the first tray,
If the distances D1 and D2 are different, raise both the first and second trays,
Tray raising means for setting the height of the upper surface of the recording sheet to the paper feeding position. The part close to the second tray is
When the recording sheet having a size larger than the first size is placed across the first and second trays, the distances D1 and D2 may be detected differently. The paper feeding device according to claim 1, wherein First and second trays that can be raised and lowered individually are provided so as to transfer a first size recording sheet placed on the second tray to the first tray, and the first tray A sheet feeding device capable of placing a recording sheet having a size larger than one over the first and second trays;
A sensor for measuring the distance to the recording sheet bundle placed on the first tray at a portion close to the second tray;
A distance D1 measured by the sensor in an equal height state where the recording sheet placement surfaces of the first and second trays are at the same height;
About the distance D2 measured by the sensor after lowering only the first tray from the contour level,
If the distance difference (D2-D1) is equal to the descending width of the first tray, raise only the first tray;
When the distance difference (D2-D1) is smaller than the descending width of the first tray, raise both the first and second trays,
Tray raising means for setting the height of the upper surface of the recording sheet to the paper feeding position. The part close to the second tray is
When a recording sheet having a size larger than the first size is placed over the first and second trays, the distance difference (D2−D1) is the same as that of the first tray. The sheet feeding device according to claim 3, wherein the sheet feeding position is a position that is detected smaller than the descending width. The sensor is
It is arranged at a position higher than the paper feeding position,
The sheet feeding device according to claim 1, wherein a distance to the upper surface of the recording sheet is measured as the distance. The sheet feeding device according to claim 5, wherein the recording sheet placement surface of the first tray has a recess or a through hole at a position corresponding to the sensor in plan view. The sensor is
It is disposed at the same position as the placement surface of the first tray or at a position lower than the placement surface,
The sheet feeding device according to claim 1, wherein a distance to the lower surface of the recording sheet is measured as the distance. The sheet feeding device according to claim 1, wherein the recording sheets placed on the first tray are fed out of the device one by one from the top. An image forming apparatus comprising the paper feeding device according to claim 1.

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