JPH04348360A - Both-side paper feeding device - Google Patents

Abstract

PURPOSE:To eliminate useless pressuring force in the case that the loading quantity of transfer paper is reduced under a condition that double feeding or non-feeding is not caused and to eliminate the waste of the load torque of an accessing member. CONSTITUTION:The transfer papers 11 having one side to which copying has been performed are successively loaded on both-side tray, the bundle of the transfer papers 11 is pressured by a pressuring member 12 and is successively fed from a lowermost transfer paper side by the accessing member 13, only the lowermost transfer paper is separated and fed by a frictional separation means 17 constituted of a carrying member 15 and a fixed preventing member 16. Then, a pressuring force varying means 19 for varying the pressuring force P to the bundle of the transfer papers 11 by the pressuring member 12 and having a driving source 18 is provided, and the quantity of transfer papers loaded on the both-side tray is detected by a stacked quantity detecting means 25. The driving source 18 is controlled by a control means 24 in accordance with the detected quantity of transfer paper, and the pressuring force P is weakened when the loaded papers are reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided paper feeding device that is installed in a double-sided copying machine to temporarily store transfer paper on which one-sided copies have been made and re-feed the paper for re-copying.

0002

2. Description of the Related Art First, let us consider the case where double-sided copying is performed using a double-sided copying machine equipped with an RDH (circulating document feeder).
Copy productivity differs depending on whether the paper feeding method of the duplex paper feeding device (double-sided tray) is an upper paper feeding method or a lower paper feeding method. In order to increase copy productivity, it is preferable to use a lower paper feeding method as the paper feeding method in the duplex tray.

Furthermore, when refeeding paper from the double-sided tray, a separation mechanism is required to avoid double feeding. For example, if an air separation method is used, it requires space for a fan and duct piping to supply air, and has the drawbacks of high noise during air suction, and high power consumption because it requires a dedicated fan. . In this respect, the frictional separation method does not require a fan or duct, and can be constructed compactly using a roller pair structure, etc., and is advantageous in terms of noise generation and power consumption.

[0004] From this point of view, a friction separation system and a bottom paper feeding system are generally used. That is, as schematically shown in FIG. 7, a feeding section 4 includes a pressure lever 2 and a pick-up roller 3 facing each other with the stacked transfer paper 1 sandwiched therebetween, and a transport roller 5 which is rotationally driven in the feeding direction and is fixed. It is composed of a reverse roller 6 and a friction separation section 7. With such a configuration, when the loaded transfer paper 1 is to be re-fed, the pressing force P of the calling roller 3 is determined based on the maximum number of sheets that can be stacked in the machine.

Specifically, the pressing force P is set to satisfy the conditions shown in (1) to (4) below.

■Conditions for transporting the transfer paper 1 to the friction separation unit 7 As shown in FIG. 7(a), the friction coefficient between the transfer paper and the roller is μRP, the friction coefficient between the transfer paper is μPP, and the transfer paper/both sides If the friction coefficient between the trays is μPL, the weight of one sheet of transfer paper 1 is m, the number of transfer sheets loaded on the double-sided tray is n, and the adhesion force is α, then μRPP1 > μPPP1 + μPPm (n-1)
+ μPLmn + α, P1 > { μPPm(n-1) + μPLmn
+ α}/(μRP− μPP)

…………………
...(1) It is shown as follows.

For example, μRP=1.2, μPP=0.4
, μPL=0.1, then from equation (1), P1 >
0.625mn-0.5m+1.25α. More specifically, if m=4gf and α=0,
P1 > 2.5n-2. Therefore, for example, if the number of sheets loaded is n = 100 sheets, the pressing force P1 is 248 gf, as shown in FIG. 8(a).
More than that is required. In reality, the adhesion force α is not 0 due to static electricity, etc., so this adhesion force α must also be taken into account, and the pressing force P1 is set to a value larger than 248 gf.

■ Conditions for separating and transporting only one sheet (non-feed prevention conditions) In addition to the above definition, if the friction coefficient between the transfer paper and the transport roller is μRsP as shown in FIG. 7(b), then the maximum For the lower transfer paper, the formula (2) is F = μRPP2 + μRPP1 − μRs
PP2 - μPPP1
−μPPm(n-1) + μPLmn
− α ……………(2) holds true. However, n≧2. Further, in order for this lowest transfer paper to be separated and conveyed, F>0 must be satisfied. Therefore, rearranging equation (2), we get
P1>{(μRsP−μRP)P2+mn(μPP+μ
PL)-μPPm+α}/(μRP-μPP)


……………(3) becomes. Here, μRP=1.2, μRsP =0.8
, μPP=0.4, μPL=0.1, P2 =400g
If f, then P1>(-0.4×400+0.5mn-
0.4m)/0.8, P1>0.625mn-200-0.5m+1.2
5α ……………(4)

For example, m=4gf (A4 size), α=
Considering the case of 0, the result is as shown in FIG. 8(b). In other words, the condition that does not cause non-delivery is P1>2.5n-202
It is to satisfy the following.

[0010] Condition for not feeding the second sheet of transfer paper (double feeding prevention condition) Referring to FIG. 7(c), the following equation (5) holds true for the second sheet of transfer paper from the bottom. That is, Q=
μPPP2+μPPP1-μPPm(n-1)-μRs
PP2-α ……………(5) However, n≧2. Here, in order not to send the second sheet of transfer paper, Q≦0 must be satisfied, so rearranging equation (5), P1≦{(μRsP−μPP)/μPP}P2+
m(n-1)-α/μPP ……………(6) where μRsP = 0.8, μPP = 0.4
, P2 = 400gf, then P≦mn+400−m−1.25α
…………………………………(7) For example, if m = 4gf and α = 0, then Figure 8 (
c). In other words, the conditions that do not cause double feeding are:
P1≦4n+396
……………………………………………(8) must be satisfied.

Taking these conditions into account, the pressure lever 2
It can be said that the pressing force P1 needs to be within the setting range as shown in FIG. Here, conventionally,
The pressing force P1 is set as P1=Pz based on the maximum number of sheets that can be loaded on the duplex tray of the copying machine.

0012

[Problem to be Solved by the Invention] However, with this setting of the pressing force P1=Pz, if the number of sheets loaded is small, a large force will be applied unnecessarily, and the torque of the calling roller 3 will be wasted accordingly. Become. Furthermore, applying a force larger than necessary is undesirable as it may cause image scratching. That is, the transfer paper 1 on which one side has been copied is stacked with the image portion 7 facing upward, as shown in FIG. Here, the pressing force P1 is set under conditions that do not cause double feeding or non-feeding, but if this pressing force P1 is too high when feeding the lowest transfer paper 1n, the upper transfer paper 1n-1 Rubbing marks corresponding to the rollers may be formed on the lower surface (back surface) of the image area 7 on the transfer paper 1n, which impairs copy quality in double-sided copying.

[0013]

[Means for Solving the Problems] Transfer sheets that have been copied on one side are stacked one after another on a double-sided tray, and while the stacked stack of transfer sheets is pressed by a pressure member, a calling member that cooperates with this pressure member is used to Claim 1: A double-sided paper feeding device in which sheets are sequentially fed from the lower transfer paper side, and only the lowest transfer paper is separated and sent to an image forming section by a friction separation means using a conveying member and a fixed blocking member. In the described invention, a pressing force variable means having a drive source and varying the pressing force of the transfer paper bundle by the pressure member is provided, and a loading amount detection means for detecting the amount of transfer paper stacked on the double-sided tray. and a control means for controlling the drive source according to the detected amount of transfer paper.

[0014] Here, in the invention as claimed in claim 2, the loaded amount detecting means includes a number detecting means for detecting the number of transfer paper sheets stacked on the double-sided tray and a weight detecting means for detecting the weight of the stacked transfer paper sheets. The number of sheets of transfer paper and the weight of the transfer paper were defined as the amount of transfer paper.

[0015] Furthermore, in the invention as set forth in claim 3, a pressing force variable means having a drive source and varying the pressing force of the transfer paper bundle by the pressure member is provided, and A loading amount detection means for detecting the amount and a size detection means for detecting the size of the transfer paper are provided, and the driving source is controlled according to the detected amount of the transfer paper, the size of the transfer paper, and the characteristic value of the paper type of the transfer paper. A control means was provided to

[0016] In this case, in the invention set forth in claim 4, an input means for inputting the characteristic value of the paper type is provided, and in the invention set forth in claim 5, this input means is an operation panel section; In the invention, the input means is capable of freely adding and deleting characteristic values of paper types. Further, in the invention as set forth in claim 7, automatic paper type setting means is provided for selecting a general characteristic value of the paper type when there is no input of the paper type.

[0017]

[Operation] The pressure applied by the pressure member is varied according to the amount of transfer paper loaded on the double-sided tray, so when the amount of loaded transfer paper becomes small under conditions that do not cause double feeding or non-feeding. By reducing the pressing force, the load is reduced, and the torque of the opposing calling member is not wasted, increasing its durability. Furthermore, image rubbing becomes less likely to occur when the amount of loaded transfer paper is reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The basic configuration of the friction separation method and lower paper feeding method is the same as that shown in FIG. A feeding section 14 is provided which includes a pressure lever 12 as a pressure member and a calling roller 13 as a calling member. In front of this feeding section 14, a friction separation section 17 is provided which includes a feed roller 15 as a conveying member that is rotationally driven in the feeding direction and a reverse roller 16 as a fixed blocking member. Here, the pressurizing lever 12 is directly connected to a pressurizing force variable means 19 having a motor 18 serving as a driving source. That is, the shaft 22 of the gear 21 is orthogonally meshed with the gear 20 that is rotated by the motor 18.
The upper end side of the pressurizing lever 12 is fixed to the pressurizing lever 12, and the pressurizing force P is configured to be varied in accordance with the rotation of the gear 21 driven by the motor 18. In addition, pressure lever 1
Pressure force P is applied to the pressure surface of No. 2 (the surface in contact with the stacked transfer paper 11).
A piezoelectric element 23 for detecting is attached. A control section 24 is connected to the motor 18 as a control means for controlling its operation.

On the other hand, the transfer paper 1 stacked on the double-sided tray
Loading amount detection means 25 for detecting the number of sheets as one transfer paper amount
is provided. The loaded amount detecting means 25 includes a filler 26 which is rotatably displaced in accordance with the height of the upper surface of the stacked transfer paper 11, and a 5-sensor 27 which detects the amount of operation of the filler 26 in, for example, five levels. That is, the five-sensor 27 has five sensors a to e. These sensors a
The optimum pressurizing force Pa to Pe is set according to ~e.

In such a configuration, for example, when the number of stacked transfer sheets 11 is large, all sensors a to e of the five sensors 27 are blocked and the detection output becomes H, as shown by the solid line in FIG. level condition. In this state, the control unit 24 checks whether the pressing force P detected by the piezoelectric element 23 is Pa, and if it changes, turns on the motor 18 to maintain the pressing force P=Pa. Thereafter, when the number of stacked transfer papers 11 decreases and the sensor a reaches the L level stage, the control section 24 drives the motor 18 so that the pressing force P is reduced to Pb. Thereafter, each time the number of stacked transfer papers 11 decreases and the output state of the 5-sensor 27 changes,
According to the flowchart shown in FIG. 2, the motor 18 is driven and the pressing force P applied by the pressure lever 12 is varied up to Pe. Note that the pressing force may be controlled to a predetermined value not based on the detection result of the piezoelectric element 23, but may be controlled based on, for example, the rotation speed of the motor 18.

Therefore, the setting of the pressing force P according to this embodiment is variable in a stepwise manner according to the number of stacked sheets, as shown by the characteristic ■ in FIG.

As described above, according to this embodiment, the transfer paper 1
Since the pressing force P applied to the pick-up roller 13 by the pressure lever 12 is varied according to the number n of sheets loaded in 1, the load can be reduced when the number of sheets loaded becomes small, and this is effective in preventing double feeding and non-feeding. There is no waste, and the durability of the calling roller 13 side is improved. Therefore, even when the number of stacked sheets decreases, problems such as image rubbing due to too strong pressing force do not occur.

As a method for knowing the number of stacked transfer sheets, a detection means may not be specially provided, and the recognition may be made on the copying machine main body side based on the number of sheets to be copied, the number of sheets to be copied, or the like.

Next, a second embodiment of the present invention will be explained with reference to FIG. In this embodiment, the amount of loaded transfer paper 11 is expressed by the loaded weight W as well as the loaded number n, and a weight detection means 28 for detecting this loaded weight W is provided. Therefore, the loading amount detection means 27 of the embodiment
functions as a means for detecting the number of loaded sheets. Here, the weight detection means 28 is constituted by a weight measuring device 30 using a strain gauge type load converter attached to both front and rear ends of the bottom plate 29 of the double-sided tray, and converts the weight W into an electrical output using the strain gauge. It is something to seek. However, the weight may be measured by other methods such as a health meter.

In such a configuration, in this embodiment,
As shown by the characteristic ■ in FIG. 3, it is varied according to P1=An+B. For such control, it is necessary to know the mass m of the transfer paper 11, and for this purpose, the detected information of the weight W of the stacked transfer paper 11 and the number of stacked sheets n0 is used. That is, m=W/n0. For example, if W=200gf and n0=50 sheets, m=4gf. In this way, when m=W/n0, A=A0m=0.625W/m, so P1=
0.625(W/n0)n+B (However, 1<
n≦n0). Here, B is a term including the adhesion force α, and may be set to any positive value. Furthermore, according to the equations for each of the conditions described above, if the value of m (=W/n0) changes, the setting area shown in FIG. 3 will naturally change as well. Furthermore, the method of varying the pressure P1 is not limited to one in which it is varied continuously according to the number of sheets loaded (n) (Characteristic ■ method); (characteristic ■ method).

Further, a third embodiment of the present invention will be explained with reference to FIGS. 5 and 6. Basically, in this embodiment, the pressing force is varied according to P1 = An + B as in the previous embodiment, but for this purpose, as a method of knowing the mass m of the transfer paper 11, the transfer paper size and the paper This method uses the characteristic value of the type, ie, the weight (or weight). That is, m = transfer paper size x (ream weight / 0.86) = transfer paper size x weight, for example, A4 size (=210mm x 297mm
) with a ream weight of 55 kg, m≒4 gf. Here, the transfer paper size can be recognized by the normal size detection means provided on the copying machine main body side, the number of loaded sheets can be recognized as in the above-mentioned embodiment, and the rest is determined by the characteristic value of the paper type ( The pressurizing force P1 may be set according to each value by inputting the information on the reciprocating amount).

For this reason, in this embodiment, an input screen 32 is provided on a part of the operation panel 31 of the copying machine, as shown in FIG. has been done. That is, as shown in the illustrated example, the ream weight can be input by inputting the paper type number. In response to such an input screen 32, control as shown in FIG. 6 is performed. Since it is necessary to determine the transfer paper size and ream weight in order to determine the pressing force P1, first it is determined whether or not to input the paper type. When inputting the paper type, the paper type No. may be input on the input screen 32. In this case, if there is no selected paper type due to unregistration, information such as paper type, size, ream weight, etc. may be directly input numerically. Through this operation, characteristic values for paper types can be added or deleted, allowing easy-to-use registration settings depending on the situation. If the paper type No., paper type, etc. are not input, a general value such as ream weight is used as the characteristic value of the paper type. Therefore, this process becomes an automatic paper type setting means, which can be used even when there is no input from the user side. On the other hand, during double-sided copying, the size of transfer paper and the number of sheets to be loaded are recognized by the copying machine itself. Therefore, based on this information, transfer paper 11
Calculate the mass m of and determine the value of A. In addition, the numerical values for B and n are called to determine the pressing force P1. Therefore, the pressure detected by the piezoelectric element 23 is this value P1
The motor 18 is driven until . After that, read the varying value of the number of loaded sheets n, calculate the pressing force according to that value,
The motor 18 is driven to vary the pressing force P1. Note that even in this embodiment, the pressing force may be varied in steps instead of linearly.

[0028]

Effects of the Invention The present invention is configured as described above, and the amount of transfer paper stacked on the double-sided tray, more specifically, the number of transfer paper sheets and the weight of the transfer paper, or the characteristic values of the transfer paper size and paper type. The pressure applied by the pressure member can be varied accordingly, so if the amount of loaded transfer paper decreases, the load can be reduced by reducing the pressure under conditions that do not cause double feeding or non-feeding. It is possible to eliminate wasted torque of the opposing calling member and improve its durability.
In addition, image rubbing due to too strong pressure when the amount of loaded transfer paper is reduced can be made less likely to occur.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation.

FIG. 3 is a characteristic diagram showing a conventional example.

FIG. 4 is a schematic front view showing a second embodiment of the present invention.

FIG. 5 is a plan view of an input screen showing a third embodiment of the present invention.

FIG. 6 is a flowchart showing operation control.

FIG. 7 is a schematic front view of various states for explaining pressurizing force setting conditions.

FIG. 8 is a characteristic diagram for explaining pressurizing force setting conditions.

FIG. 9 is a schematic front view for explaining image rubbing.

[Explanation of symbols]

11 Transfer paper 12 Pressure member 13 Calling member 15 Conveyance member 16 Blocking member 18 Drive source 19 Pressure force variable means 24 Control means 25 Loading amount detection means & number of sheets detection means 28
Weight detection means 31 Operation panel 32 Input means

Claims (7)

[Claims] Claim 1: The transfer sheets on which single-sided copies have been copied are stacked one after another on a double-sided tray, and while the stacked transfer paper bundles are pressed by a pressure member, a calling member that cooperates with the pressure member is used to transfer the sheets to the lowest transfer paper side. In a double-sided sheet feeding device that feeds sheets sequentially, and separates only the lowest transfer sheet by a friction separation means using a conveyance member and a fixed blocking member and sends it to an image forming section, A pressing force variable means is provided to vary the pressing force of the transfer paper bundle by the pressure member, and a loading amount detecting means is provided to detect the amount of transfer paper stacked on the double-sided tray, and according to the detected amount of transfer paper. A double-sided paper feeding device, comprising a control means for controlling the drive source. 2. The loading amount detection means includes a number detection means for detecting the number of transfer paper sheets stacked on the double-sided tray and a weight detection means for detecting the weight of the stacked transfer paper sheets. 2. The double-sided paper feeding device according to claim 1, wherein the weight is the amount of transferred paper. 3. The transfer sheets that have been copied on one side are stacked one after another on the duplex tray, and while the stacked transfer paper bundles are pressed by a pressure member, a calling member that cooperates with the pressure member is used to transfer the sheets to the lowest transfer paper side. In a double-sided sheet feeding device that feeds sheets sequentially, and separates only the lowest transfer sheet by a friction separation means using a conveyance member and a fixed blocking member and sends it to an image forming section, A pressing force variable means for varying the pressing force of the bundle of transfer paper by the pressure member is provided, and a loading amount detecting means for detecting the amount of transfer paper stacked on the double-sided tray and a size detecting means for detecting the size of the transfer paper. A double-sided paper feeding device comprising: a control means for controlling the drive source according to the detected transfer paper amount, transfer paper size, and characteristic values of the paper type of the transfer paper. 4. The double-sided paper feeding device according to claim 3, further comprising input means for inputting characteristic values of paper types. 5. The double-sided paper feeding device according to claim 4, wherein the input means is an operation panel section. [Claim 6] The input means includes adding characteristic values of paper types;
Claim 4 or 5 is characterized in that it is deletable.
Double-sided paper feeder as described. 7. The double-sided paper feeding device according to claim 4, further comprising automatic paper type setting means for selecting a general characteristic value of the paper type when there is no input of the paper type.