Patent Grant
7654523
1. Field of the Invention
The invention relates to an image forming device and particularly to the sheet transport device of the image forming device.
2. Description of Related Art
A paper feed member of this type of sheet transport device is so constructed that when two or more sheets are transported to a nip unit, one sheet is separated and transported to the downstream side in the sheet transport direction by a paper feed roll rotated to apply the force in the transport direction to the sheets transported to the nip unit and a separating member coming into contact with the transported sheets to generate the force for hindering the transport of the sheets. As the separating member brought into pressure contact with the paper feed roll, used is a roll-like member or a pad-like member having a pressure contact surface to the paper feed roll. In the case of using the roll-like member (a separation roll) as the separating member, the separation roll is rotated in the reverse direction to the sheet transport direction, thereby applying not only the force for hindering the transport of the sheets, but also the force for transporting the same in the reverse direction.
When the pressure contact force (pressure contact force of the nip unit, that is, the nip pressure) of the paper feed roll of the paper feed member and the separating member is too small or large, the transport force of the pick-up roll is too large or small, or the relationship between the transport force of the pick-up roll and the nip pressure is unsuitable, the sheets can't be surely transported one by one to the downstream side in the sheet transport direction of the paper feed member.
In the sheet transport device to which the invention applies, for example, when the contact pressure force (nip pressure) of the paper feed roll of the paper feed member and the separating member is too small, misfeed (sheet transport is not accomplished by the paper feed member) is caused. In the case where the pressure contact force is too large, when two or more sheets are simultaneously transported to the nip unit, one of the sheets can't be separated to cause multifeed of sheets (two or more sheets are transported to the downstream side without separation).
In order to prevent the occurrence of abnormal conditions in transporting a sheet, various proposals have been made heretofore, and the techniques described in the following Patent References are publicly known.
(1) Technique described in the Patent Reference 1 (Japanese Published Unexamined Patent Application No. Hei-5-32356)
According to the technique described in the patent document, a paper sheet picked up by a nudger roller (pick-up roll) is transported to a nip unit (a pressure contact area) between a feed roller (a paper feed roll) and a retard roller (a separating member) constituting a paper separating mechanism. When misfeed or multifeed is detected according to a detection signal of a misfeed detecting sensor and a multifeed detecting sensor disposed on the downstream side of the nip unit (the pressure contact area), the nip pressure (the pressure of the nip unit) is automatically controlled at any time.
(2) Technique described in the Patent Reference 2 (Japanese Published Unexamined Patent Application No. Hei-10-45272)
This Patent Reference describes a separating device including a transport roller rotated in the paper feed direction and a separation roller brought into pressure contact with the transport roller and rotated in the reverse direction to the paper feed direction. The pressure contact force of the transport roller and the separation roller is set to a small value not to feed a sheet properly at the start of feeding a sheet. The pressure contact force regulating part is controlled so that the value is gradually increased until a sheet detecting part determines the proper feeding of the sheet, and then the value at the time is kept until the separation of the sheets is completed.
(3) Technique described in the Patent Reference 3 (Japanese Published Unexamined Patent Application No. Hei-9-150990)
This Patent Reference describes the technique for transporting a paper sheet transported by a pick-up roller 20 to a pressing portion between a separation roller 21 and an opposite member 25, separating one paper sheet coming into contact with the peripheral surface of the separation roller 21, and transporting the same toward the downstream in the paper transport direction. In the technique, according to the detected speed of a paper transport speed detecting roller 41 disposed on the downstream from the separation roller 20, the pressing force P of the pick-up roller 20 and the separating force of the separation roller 21 are controlled to control the paper transport speed to a proper value, thereby normally transporting the paper sheet.
In order to normally transport the sheet as in the Patent References 1 to 3, various sheet multifeed detection methods for detecting the occurrence of abnormal sheet transport have been proposed heretofore, and the techniques described in the following Patent References (4) to (6), for example, are publicly known.
(4) Patent Reference 4 (Japanese Published Unexamined Patent Application No. Hei-11-301885)
This Patent Reference describes the technique for deciding multifeed of sheets according to the electrostatic capacity of a parallel plate electrode capacitor.
(5) Patent Reference 5 (Japanese Published Unexamined Patent Application No. 2000-095390)
This Patent Reference describes the technique for disposing an ultrasonic oscillator and a receiver on the upper side and lower side of a sheet transport path, and detecting the multifeed of sheets according to the information obtained from the oscillator and receiver.
(6) Patent Reference 6 (Japanese Published Unexamined Patent Application No. Hei-8-198478)
This Patent Reference describes the technique for detecting the multifeed of sheets according to the moving distance of a detecting roller to a transport roller when the sheet is transported.
[Patent Reference 1]: Japanese Published Unexamined Patent Application No. Hei 5-32356 (Paragraph No. [0009], FIG. 1)
[Patent Reference 2]: Japanese Published Unexamined Patent Application No. Hei 10-45272 (Paragraph No. [0015], FIG. 4)
[Patent Reference 3]: Japanese Published Unexamined Patent Application No. Hei 9-150990 (Paragraph No. [0015], [0015], [0017] to [0020], FIG. 1)
[Patent Reference 4]: Japanese Published Unexamined Patent Application No. Hei 11-301885 (Abstract on page 1)
[Patent Reference 5]: Japanese Published Unexamined Patent Application No. 2000-095390 (Abstract on page 1)
[Patent Reference 6]: Japanese Published Unexamined Patent Application No. Hei 8-198478 (Abstract on page 1)
In all techniques described in the above Patent References 4 to 6, multifeed is detected when the sheets pass through the preset position of the multifeed sensor. Accordingly, in the case where the multifeed is released by regulating the nip pressure or the like, release of multifeed can't be detected until the sheets to be separated are sent back and returned to the multifeed sensor position, resulting in causing delay in detection. On the other hand, in the case where the sheets to be separated are stopped in spite of the separating action, detection of multifeed remains as it is.
The present invention has been made in view of the above circumstances and provides an image forming device, which may improve the determination accuracy for the sheet multifeed state.
The invention proposed to solve the above problems will now be described. The elements of the invention are designated by parenthesizing the reference numerals and signs of elements of an embodiment to facilitate correspondence between the invention and an embodiment mentioned later. The reason why the invention is described by a correspondence with the reference numerals and signs of an embodiment mentioned later is that the invention may be easily understood, not that the scope of the invention is limited to an embodiment.
In order to solve the problems, an image forming device for a sheet to which the invention is applied includes a paper feed member which applies a force in a transport direction to the sheet and a separating member which applies a force in a direction of hindering the sheet transport, and in the apparatus, two or more multifed sheets are separated by the paper feed member and the separating member. The image forming device includes a sheet speed detecting part which detects a transport speed V2 of a sheet on the separating member side, a multifeed sheet detecting part which detects the transport of plural sheets, and a control part which determines to be non-multifeed and controls paper feed when the speed V2 detected by the sheet speed detecting part is V2≦0 and the multifeed sheet detecting part detects the transport of the plural sheets.
An image forming device for a sheet to which another invention is applied includes a paper feed member which applies a force in a transport direction to a sheet, and a separating member which applies a force in a direction of hindering the sheet transport, and in the apparatus, two or more multifed sheets are separated by the paper feed member and the separating member. The image forming device includes a paper feed member side sheet speed detecting part which detects a transport speed V1 of a sheet on the paper feed member side, a separating member side sheet speed detecting part which detects a transport speed V2 of a sheet on the separating member side, a multifeed sheet detecting part which detects the transport plural sheets, and a control part which controls paper feed when a relationship between the speed V1 detected by the paper feed member side sheet speed detecting part and the speed V2 detected by the separating member side sheet speed detecting part is V1>V2>0 and the multifeed sheet detecting part detects the transport of the plural sheets.
In order to solve the problems, a multifeed state determination device for a sheet according to another invention is characterized by providing the following constituent features (A01) to (A04).
(A01) A paper feed member (Rs) including a paper feed roll (Rs1) and a separating member (Rs2) forming a nip unit (N) by mutually pressure contact portions or mutually adjacent and opposite portions, wherein the paper feed roll (Rs1) rotates to apply the force in the transport direction to a sheet (S) transported to the nip unit (N), and the separating member (Rs2) generates the force for hindering the transport when it comes into contact with the transported sheet (S), whereby when two or more sheets (S) picked up from paper feed trays (TR1, TR2) by a pick-up roll (Rp) are transported to the nip unit (N), one sheet (S) on the paper feed roll (Rs1) side of two or more sheets (S) is separated and fed to the downstream side in the sheet transport direction.
(A02) A separating member side sheet speed detecting part (C3) which detects the transport speed V2 of a sheet surface on the separating member (Rs2) side of a sheet (S) in the course of passing through the nip unit (N), which is a pressure contact area of the paper feed roll (Rs1) and the separating member (Rs2).
(A03) A multifeed sheet detecting part (C1) which detects the presence of two or more sheets (S) in the course of being transported through the nip unit (N).
(A04) A multifeed state determination part (C4) which determines to be not in the multifeed state of the sheets (S) in the case where the sheet speed V2 detected by the separating member side sheet speed detecting part (C3) is V2≦0, and determines to be in the multifeed state of the sheets (S) in the case of V2>0 when the multifeed sheet detecting part (C1) is in the state of detecting the multifed sheets.
In the above determination device for the sheets (S) having the constituent features (A01) to (A04), the paper feed member (Rs) has the paper feed roll (Rs1) and the separating member (Rs2) forming the nip unit (N) by the mutually pressure contact portions or the mutually adjacent and opposite portions. When two or more sheets (S) picked up from the paper feed trays (TR1, TR2) by the pick-up roll (Rp) are transported to the nip unit (N), the paper feed roll (Rs1) rotates to apply the force in the transport direction to the sheet transported to the nip unit (N), and the separating member (Rs2) generates the force for hindering when it comes into contact with the transported sheet (S). The paper feed member (Rs) having the paper feed roll (Rs1) and the separating member (Rs2) separates one sheet (S) on the paper feed roll (Rs1) side of two or more sheets (S) transported to the nip unit (N), and feeds the sheet toward the downstream in the sheet transport direction.
The separating member side sheet speed detecting part (C3) detects the transport speed V2 of the sheet surface on the separating member (Rs2) side of the sheet (S) in the course of passing through the nip unit (N) which is a pressure contact area of the paper feed roll (Rs1) and the separating member (Rs2).
The multifeed sheet detecting part (C1) detects the presence of two or more sheets (S) in the course of being transported through the nip unit (N).
The multifeed state determination part (C4) determines to be not in the multifeed state of the sheets (S)in the case where the sheet speed V2 detected by the separating member side sheet speed detecting part (C3) is V2≦0, and determines to be in the multifeed state of the sheets (S) in the case of V2>0 when the multifeed sheet detecting part (C1) is in the state of detecting the multifed sheets.
According to an aspect of the present invention, even if the multifeed sheet detecting part (C1) detects the presence of two or more sheets (S) in the course of being transported through the nip unit (N), in the case of V2≦0, the sheets (S) at the nip unit (N) are sent back or stopped, highly probably the multifeed is released or already has been released. In this case, the multifeed state is not decided so that the accuracy of determining the sheet multifeed state can be improved.
Further, a multifeed state determination device for a sheet according to another aspect of the invention is characterized by providing the following constituent features (A01), (A02), (A03′), (A04′).
(A01) A paper feed member (Rs) including a paper feed roll (Rs1) and a separating member (Rs2) forming a nip unit (N) by mutually pressure contact portions or mutually adjacent and opposite portions, wherein the paper feed roll (Rs1) rotates to apply the force in the transport direction to a sheet S transported to the nip unit (N), and the separating member (Rs2) generates the force for hindering the transport when it comes into contact with the transported sheet (S), whereby when two or more sheets (S) picked up from paper feed trays (TR1, TR2) by a pick-up roll (Rp) are transported to the nip unit (N), one sheet (S) on the paper feed roll (Rs1) side of two or more sheets (S) is separated and fed to the downstream side in the sheet transport direction.
(A02) A separating member side sheet speed detecting part (C3) which detects the transport speed V2 of a sheet surface on the separating member (Rs2) side of a sheet (S) in the course of passing through the nip unit (N), which is a pressure contact area of the paper feed roll (Rs1) and the separating member (Rs2).
(A03′) A paper feed roll side sheet speed detecting part (C2) which detects the transport speed V1 of the sheet surface on the paper feed roll (Rs1) side of the sheet S passing through the nip unit (N).
(A04′) A multifeed state determination part (C4), which determines the multifeed state of the sheets (S) when V1>V2>0 in the case where the sheet speed detected by the paper feed roll side sheet speed detecting part (C2) is taken as V1, the sheet speed detected by the separating member side sheet speed detecting part (C3)is taken as V2.
In the multifeed state determination device for the sheet (S) according to the invention having the above constituent features (A01), (A02), (A03′), (A04′), the paper feed member (Rs) has the paper feed roll (Rs1) and the separating member (Rs2) forming the nip unit (N) by the mutually pressure contact portions or the mutually adjacent and opposite portions. When two or more sheets (S) picked up from the paper feed trays (TR1, TR2) by the pick-up roll (Rp) are transported to the nip unit (N), the paper feed roll (Rs1) rotates to apply the force in the transport direction to the sheet transported to the nip unit (N), and the separating member (Rs2) generates the force for hindering the transport when it comes into contact with the transported sheet (S). The paper feed member (Rs) having the paper feed roll (Rs1) and the separating roll separates one sheet (S) on the paper feed roll (Rs1) side of two or more sheets (S) transported to the nip unit (N), and feeds the sheet toward the downstream in the sheet transport direction.
The separating member side sheet speed detecting part (C3) detects the transport speed V2 of the sheet surface on the separating member (Rs2) side of the sheet (S) in the course of passing through the nip unit (N) which is a pressure contact area of the paper feed roll (Rs1) and the separating member (Rs2).
The paper feed roll side sheet speed detecting part (C2) detects the transport speed V1 of the sheet surface on the paper feed roll (Rs1) side of the sheet (S) in the course of passing through the nip unit (N).
The multifeed state determination part C4 determines the multifeed state of sheets (S) in the case of V1>V2 0 when the sheet speed detected by the paper feed roll side sheet speed detecting part (C2) is taken as V1, and the sheet speed detected by the separating member side sheet speed detecting part (C3) is taken as V2.
According to another aspect of the invention, even if the multifeed sheet detecting part (C1) detects the presence of two or more sheets (S) in the course of passing through the nip unit (N), in the case of V2≦0, the sheets (S) at the nip unit (N) are sent back or stopped, so that the multifeed is highly probably released or has already been released. In this case, the multifeed state is not decided so as to improve the accuracy of determining the sheet multifeed state.
Preferred embodiments of the present invention will be described in detail based on the followings, and the invention is not limited to the followings, wherein:
In
The automatic document transport device U2 has a document feed tray TG1 where two or more original document Gi to be copied are placed in a stack. The two or more original documents Gi placed in the document feed tray TG1 are respectively sequentially discharged through the copying position on the platen glass PG to a document discharge tray TG2.
The copying machine U1 has a UI (user interface), an IIT (image input terminal) as an image read unit, an IOT (image output terminal) as an image recording operation unit, and an IPS (image processing system) provided on the IIT or IOT, which are sequentially disposed below the platen glass PG.
The IIT as a document reader disposed below the transparent platen glass PG on the top face of the copying machine body U1 has an exposure system registration sensor (platen registration sensor) Sp disposed in a platen registration position and an exposure optical system A.
The exposure optical system A is controlled to move and stop according to a detection signal of an exposure system registration sensor Sp and normally stopped in a home position.
In the ADF mode of copying with the automatic document feeder U2, the respective original documents Gi sequentially passing through the copying position on the platen glass PG are exposed with the exposure optical system A stopped in the home position.
In a platen mode of manually placing an original document Gi on the platen glass PG and copying the same by an operator, the exposure optical system A exposure-scans the original document on the platen glass PG while moving.
The reflected light from the exposed original document Gi is converged through the exposure optical system A on a Charge Coupled Device (solid-state image pickup element). The CCD converts the reflected light of the original document converged on the imaging surface to an electric signal.
The IPS converts a read image signal input from the CCD to a digital image write signal, and outputs the same to a laser driving signal output device DL of the IOT.
The laser driving signal output device DL outputs a laser driving signal according to the input image data to an ROS (latent image write scanner). The IPS, the laser driving signal output device DL, a power supply circuit and the like are controlled to operate by a controller C formed by a computer.
A photoreceptor drum (toner image bearing member) PR disposed below the ROS is rotated in the direction of an arrow Ya. The surface of the photoreceptor drum PR is charged to, for example, minus 700V by a charger (charge roll) CR in a charging area Q0, and then exposure-scanned by a laser beam L of the ROS (latent image write device) at a latent image writing position Q1 to form an electrostatic latent image with −300 V or the like. The latent image formation on the photoreceptor drum PR by the laser beam L is started in a lapse of designated time after a sheet sensor (not shown) detects the leading edge of a sheet. The surface of the photoreceptor drum where the electrostatic latent image is formed is rotated and moved to sequentially pass through a developing area Q2 and a transfer area (image recording position) Q4.
A developing device D for developing the electrostatic latent image in the developing area Q2 carries a developer containing toner of minus charging polarity and carrier of plus charging polarity to the developing area Q2 by a developing roll R0 to develop the electrostatic latent image on the photoreceptor drum PR passing through the developing area Q2 into a toner image Tn.
In the transfer area (image recording position) Q4, a transfer roll RT opposite to the photoreceptor drum PR is a member for transferring the toner image on the surface of the photoreceptor drum PR to the sheet S, and transfer voltage opposite in polarity to the charging polarity of toner for development used in the developing device D is supplied to the transfer roll from a power supply circuit E. Bias such as charging bias applied to the charging roll, development bias applied to the developing roll, transfer bias applied to the transfer roll TR, and the power supply circuit E having a heater power supply for heating a heater of a heat roll of a fixing device F mentioned later are controlled by the controller C.
A first paper feed tray TR1 and a second paper feed tray TR2 are arranged on the upper and lower sides in the lower portion of the image forming device body U1.
A pick-up roll Rp is disposed at the upper end of the right end of each of the first paper feed tray TR1 and second, paper feed tray TR2, and a sheet picked up by the pick-up roll Rp is transported to the right paper feed path SH1 of the respective paper feed trays TR1 and TR2.
In the paper feed path SH1, a paper feed member Rs is disposed, and the paper feed member Rs has a paper feed roll Rs1 and a separation roll (separating member) Rs2 forming a nip unit by mutual pressure contact portions thereof. The sheets transported to the nip unit are separated one by one by the paper feed member Rs and transported to the downstream portion of the sheet transport path SH1. The downstream portion of the sheet transport path SH1 is extended up and down, and a transport roll Rb rotated in the normal and reverse directions (normal and reverse rotation transport roll) is disposed in the portion. The sheet S transported to the sheet transport path SH1 is transported to an upper upstream sheet transport path SH2 by the normal and reverse rotation transport roll Rb.
The sheet S transported to the upstream sheet transport path SH2 is transported to a register roll Rr by the transport roll Ra. The sheet S transported to the register roll Rr is transported from a pre-transfer sheet guide SG1 to the transfer area Q4 in time to the moving of the toner image on the photoreceptor drum PR to the transfer area (image recording position) Q4.
The toner image Tn developed on the surface of the photoreceptor drum PR is transferred to the sheet S by the transfer roll TR in the transfer area Q4. After transfer, the surface of the photoreceptor drum PR is cleaned by a photoreceptor cleaner CL1 to remove residual toner. Subsequently static electricity is eliminated from the photoreceptor surface by a photoreceptor static eliminator JL and again charged by the charging roll CR.
An image recording member G (PR+CR+ROS+D+TR+CL1+JL) is formed of the photoreceptor drum PR, the charging roll CR, the ROS (latent image write device), the developing device D, the transfer roll TR, the photoreceptor cleaner CL1, the photoreceptor static eliminator JL and so on.
A downstream sheet transport path SH3 for a recorded sheet S where a toner image is recorded in the transfer area Q4 is provided on the downstream side in the sheet transport direction of the transfer area (image recording position) Q4. The sheet S to which the toner image is transferred by the transfer roll TR in the transfer area (image recording position) Q4 is separated from the surface of the photoreceptor drum PR, and transported to the fixing area Q5 by a sheet guide SG2 of the downstream sheet transport path SH3 and a sheet transport belt BH. The sheet S having the toner image is heat fixed by the fixing device F when passing through the fixing area Q5, and then transported to the discharged paper tray TRh through a sheet discharge path SH4.
In the sheet discharge path SH4, a switching gate (sheet transport direction control member) GT is disposed on the downstream side of the fixing device F. The switching gate GT switches the transport direction of the sheet S passed through the fixing device F between the discharged paper tray TRh side and the sheet reverse connecting path SH5. The sheet reverse connecting path SH5 connects the upstream end of the sheet discharge path SH4 (downstream portion of the fixing device F) with the sheet transport path SH1.
In the case of both-sided copying, a one-side recorded sheet S where a toner image of the first side is already recorded is transported through the switching gate GT from the sheet reverse connecting path SH5 toward the lower side of the paper feed path SH1 by the normal and reverse rotation transport roll Rb at the upper end of the paper feed path SH1, and then switched back and reversed to be again transported to the upper upstream sheet transport path SH2.
The one-side recorded sheet S, which has been again transported to the upstream sheet transport path SH2 in the reverse state is again transported to the transfer area (image recording position) Q4 to transfer a toner image to the second side of the sheet.
In
A rotary lever 2 is rotatably supported on a shaft 1 of the paper feed roll Rs1, and a pick-up roll Rp is rotatably supported on the left end of the rotary lever 2. The rotary lever 2 is always pulled downward by a tension spring 3, and subjected to the counter clockwise turning force around the shaft 1. The top face of an eccentric cam 4 abuts on the lower surface of the rotary lever 2, so that the sheet pressing force (the force for pressing the top face of the sheets S accommodated in the paper feed tray TR1) of the pick-up roll Rp can be controlled by rotating the eccentric cam 4. The eccentric cam 4 is rotated by a pressing force regulating motor M2 (See
The shaft of the separation roll Rs2 is rotatably supported on a rotary arm 6, the rotary arm 6 is rotatable around a shaft 6a, and the right end of the rotary arm 6 is pulled downward by a tension spring 7. The lower end of the tension spring 7 is connected to the upper end of a vertically movable rack 8. The rack 8 is capable of sliding up and down along a slider 9 by rotation of a pinion 10 driven to rotate by a nip pressure regulating motor (nip regulating member) M1 (See
The pressure of the nip unit N (nip pressure) can be regulated by controlling the position of the pinion 10.
A paper feed roll side sheet speed sensor SN1 for detecting the moving speed of the sheet surface on the paper feed roll Rs1 side of the sheet passing through the nip unit N is disposed on the upper side of the nip unit N, and a separation roll side sheet speed sensor SN2 for detecting the moving speed of the sheet surface of the separation roll Rs2 side of the sheet passing through the nip unit N is disposed on the lower side of the nip unit N.
On the upper side of the nip unit N, a multifeed detecting lever (sheet multifeed detector) 12 for detecting that plural sheets are transported in a pile to the nip unit N is supported to be rotatable around a shaft 12a, and a multifeed detecting roller 12b is supported to be rotatable on the tip of the multifeed detecting lever 12.
An opposite roller 13 is rotatably supported opposite to the multifeed detecting roller 12b on the lower side of the nip unit N. When a sheet enters between the multifeed detecting roller 12b and the opposite roller 13, the multifeed detecting roller 12b is lifted up according to the thickness of the sheet to turn the multifeed detecting lever 12. The thickness of the sheet entering the nip unit N can be detected by a sensor (multifeed sheet sensor) SN4 (See
On the downstream side of the nip unit N, a sheet sensor SN3 is disposed, and when the sheet sensor SN3 detects the leading end of the sheet, it can be detected that the sheet is transported through the nip unit N.
In
The paper feed roll side sheet speed sensor SN1 and the separation roll side sheet speed sensor SN2 shown in
The rotary speed sensors using the encoders shown in
(Description of the Control Unit of the Sheet Transport Device)
In
(Signal Input Element Connected to the Controller C)
Signals of the UI (user interface), the paper feed roll side sheet speed sensor SN1, the separation roll side sheet speed sensor SN2, the sheet sensor SN3 for detecting that a sheet is transported to the nip unit N, the sheet multifeed sensor SN4, and the other signal input elements are input to the controller C.
The UI is provided with a display device, a tray selection key, a mode select key and the like.
(Controlled Elements Connected to the Controller C)
The controller C is connected to a nip pressure regulating motor driving circuit D1, a separation roll driving motor driving circuit D2, a pressing force regulating motor driving circuit D3, a power supply circuit E, and the other controlled elements, and operation control signals thereof are output.
The nip regulating motor driving circuit D1 regulates the nip pressure by elevating the rack 8 (See
The separation roll driving motor driving circuit D2 drives the separation roll Rs2 to rotate in the reverse direction to the sheet transport direction through the separation roll driving motor M2, and regulates a driving current to control the turning torque.
The pressing force regulating motor driving circuit D3 rotates the cam 4 (See
The power supply circuit E has a developing bias power supply circuit for applying developing bias to the developing roll of the developing device D, a charging power supply circuit for applying charging voltage to the charging roll CR (charging roll), an LD driving power supply circuit, a transfer power supply circuit, a fixing power supply circuit and the like, and the operation timing or the like thereof is controlled by the controller C.
(Function of the Controller C)
The controller C has the following control elements C1 to C6), and the respective control elements C1 to C6 have designated functions for performing the processing according to the input signals from the signal output elements to output control signals to the respective controlled elements.
C1: Multifeed Sheet Detecting Part
The multifeed sheet detecting part C1 detects whether the presence of multifed sheets or not according to a detection signal of the multifeed sheet sensor SN4.
C2: Paper Feed Roll Side Sheet Speed Detecting Part
The paper feed roll side sheet speed detecting part C2 detects the paper feed roll side sheet speed V1 according to a detection signal of the paper feed roll side sheet speed sensor SN1.
C3: Separation Roll Side (Separating Member Side) Sheet Speed Detecting Part
The separation roll side sheet speed detecting part C3 detects the separation roll side sheet speed V2 according to a detection signal of the separation roll side sheet speed sensor SN2.
C4: Multifeed State Determination Part
The multifeed state determination part C4 has a multifeed state determination table C5a (See
C5: Separation Roll Rotation Control Part
The separation roll rotation control part C5 rotates the separation roll Rs2 in the reverse direction to the sheet transport direction in the condition where the multifeed state determination part C5 determines to be multifeed.
C6: Nip Regulating Part
The nip regulating part C6 controls the operation of the nip pressure regulating motor (nip regulating member ) M1 to release the multifeed in the condition where the multifeed state determination part C4 determines to be multifeed.
In
The processing of each step (ST) of the flowchart in
The sheet multifeed state determination processing shown in
In the step ST2, it is determined whether the leading edge of the sheet passes through the nip unit or not. If NO, the step ST2 is repeated, and if YES, the transition to the next step ST3 occurs.
In the step ST3, it is determined whether two or more sheets are present in the nip unit or not. This determination is performed depending on whether the multifeed sensor SN4 is OFF or ON. If NO, the transition to the step ST7 occurs, and if YES, the transition to the next step ST4 occurs.
In the step ST4, the following processing (1) to (3) is performed.
In the step ST5, it is determined whether multifeed or not. This determination is performed according to the sheet multifeed state determination table C5a (See
In the step ST6, a multifeed discrimination flag FL is set to “1”.
In the step ST7, the multifeed discrimination flag FL is set to “0”.
Subsequently, in the step ST8, it is determined whether the sheet trailing edge passes through the nip unit or not. If NO, it returns to the step ST3, and if YES, it returns to the step ST1.
In the step ST11 of
In the step ST12, the nip pressure S is set to the initial value S0. Subsequently, the transition to the step ST13 occurs.
In the step ST13, it is determined whether the sheet leading edge passes through the nip unit or not. If NO, the step ST13 is repeated, and if YES, the transition to the step ST14 occurs.
In the step ST14, it is determined whether the multifeed discrimination flag FL is “1” or not. If NO, the transition to the step ST15 occurs, and if YES, the transition to the step ST18 occurs.
In the step ST15, the nip pressure S is fixed and kept. Subsequently, the transition to the step ST16 occurs.
In the step ST16, it is determined whether the sheet trailing edge passes through the nip unit or not. If NO, it returns to the step ST14, and if YES, it returns to the step ST17.
In the step ST17, it is determined whether the job is ended or not. If NO, it returns to the step ST13, and if YES, it returns to the step ST11.
In the step ST18, the nip pressure S is taken as S=S−ΔS. ΔS is a very small preset value. Subsequently, the transition to the step ST19 occurs.
In the step STl9, it is determined whether the multifeed discrimination flag FL is “0” or not. If YES, the transition to the step ST15 occurs, and if NO, the transition to the step ST20 occurs.
In the step ST20, it is determined whether the nip pressure S reaches the lower limit value or not. If NO, it returns to the step ST18, and if YES, the transition to the step ST21 occurs.
In the step ST21, the job stop request flag FL2 is set to “1”. The initial value of the job stop request flag FL2 is set to “0”. Subsequently, it returns to the step ST11.
(Operation of the Device)
When the nip pressure is controlled according to the flowchart of
In
In the device, it is determined whether the sheets are in the multifeed state or not according to the detection value of the multifeed sheet detecting part C1 and the value of the paper feed roll side sheet speed V1 or the separation roll side sheet speed V2, whereby the sheet multifeed state can be accurately determined.
(Modified Form)
Although a mode for carrying out the invention is described in detail, the invention is not limited to the modes for carrying out the invention, but modifications may be made within the scope of the gist of the invention. Modifications of the mode for carrying out the invention will now be illustrated.
(H01) Although the nip pressure is regulated as a control parameter in the device, it is possible to regulate a driving current of the separation roll driving motor M1 instead of the nip pressure. In this case, the torque limiter is removed, and the separation torque of the separation roll can be regulated by the torque of the motor M1. The torque of the motor M1 is regulated by a driving current.
(H02) The invention can be applied to the image forming device other than the printer such as a copying machine.
(H03) The invention can be applied to the image forming device using image write devices other than a laser write device, for example, a liquid crystal panel, a light emitting diode or a vacuum fluorescent display.
The entire disclosure of Japanese Patent Application No. 2003-081418 filed on Mar. 24, 2003 including specification, claims, drawings and abstract is incorporated herein by reference in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2003-081418 | Mar 2003 | JP | national |
This application is a Divisional of U.S. patent application Ser. No. 10/682,295, filed Oct. 10, 2003 now U.S. Pat. No. 7,234,695, and claims the benefit of Japanese Patent Application No. 2003-081418, filed Mar. 24, 2003, both of which are hereby incorporated by reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20070257418 A1 | Nov 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10682295 | Oct 2003 | US |
| Child | 11798265 | US |
