DE69016234T2 - Sheet transport device. - Google Patents

Description

Background of the invention Field of the invention

The present invention relates generally to a device for transporting a sheet, and more particularly to a sheet transport device having the function of transporting, for example, a sheet which is successively inserted from the outside by a manual sheet insertion.

Relevant state of the art

An electronic copying machine 100 of the conventional type shown in Fig. 1 is arranged to transport a sheet fed by manual sheet feeding in the following manner. A manual sheet feeding tray 101 is inclined toward the outside, and a sheet-shaped transfer medium 102 is fed from the tray 101. The transfer medium 102 is transported by paper transport rollers 103 and 105 and registration rollers 106 and guided through the gap between transport guides 107 and 109 toward a drum 111. When an image formed on the drum 110 is transferred to the transfer medium 102 as a toner image by means of a transfer charger 111, the transfer medium 102 is separated from the drum 110 by a separation charger 112. Then, the transfer medium 102 is transported via a transport section 113 to a fixing roller section 115 in which the toner image is fixed. The fixed transfer medium 102 is finally discharged onto a discharge tray 116. During the above process, the transfer medium 102 is transported in the constant direction.

When a multiple image is to be formed after the completion of fixing, the transfer medium 102 which has passed through the fixing section 115 is deflected by means of a medium deflection plate 117 to a two-sided/multi-copy sheet transport path 119. The transfer medium 102 passes through the transport path 119 and is again transported to the drum 110 and the fixing roller section 115. When images are to be produced on the opposite surfaces of the transfer medium 102, the discharge rollers 120 are reversed during the discharge of the transfer medium 102. The transfer medium 102 is guided by the medium deflector plate 117 and again conveyed via the transport path 119 to the drum 110.

However, the arrangement described above involves a number of problems. For example, because the manual sheet feed tray 101 is arranged on the right side of the electronic copying machine 100, an operator must tilt the tray 101 to the right and place the transfer medium 102 thereon. It is therefore necessary to leave sufficient space on the right side of the copying machine 100, with the result that the space utilization by installing the copying machine 100 is impaired.

Another problem is pointed out with respect to a conventional arrangement in which the transfer medium 102 is conveyed from the manual sheet insertion tray 101 provided at the front of the electronic copying machine 100 in a direction substantially orthogonal to the double-sided/multi-copy sheet transport path 119. For example, such a conventional arrangement requires the provision of means for orthogonal transport, means for positioning the transfer medium 102, means for switching the transport mechanism of the double-sided/multi-copy sheet transport path 119, and other associated parts. As a result, the copying machine 100 increases in height.

It has also been proposed to use an arrangement such as that shown in Fig. 2. According to Fig. 2, a manual sheet feed tray projects to the right, and a Sheet receiving tray (cassette) is installed in a bottom part of the copier at the front of the copier. A two-sided/multi-copy sheet transport path is arranged above the sheet receiving tray. However, this arrangement presents problems similar to those described above.

Summary of the invention

It is therefore an object of the present invention to provide a sheet transport device which enables manual sheet insertion to be carried out smoothly, as well as an image forming system equipped with such a sheet transport device.

To achieve the above object, according to this invention, as defined in claim 1, there is provided a sheet transport device including two sheet transport paths arranged in mutually different planes and crossing each other at approximately right angles, and a pair of guide plates operable to move between the two sheet transport paths at the intersection thereof. The sheet transport device further includes guide plate driving means for moving said guide plates from one to the other of the two transport paths, and sheet transport means for transporting the sheet from one to the other of the two transport paths by changing the transport direction of the sheet.

This arrangement does not require the space which has been required to arrange two transport paths one above the other as in a conventional type transport device in which two transport paths arranged in the same direction are switched over. Accordingly, it is possible to reduce the space required for installing the copying machine, that is, to provide a small-sized copying machine. Moreover, the present invention can also be applied to, for example, a two-sided/multi-copying machine of the type which has a manual sheet-feeding transport path. which crosses a part of a return transport path at approximately right angles. With this arrangement, the return transport path can also be used as a front-type manual sheet feeding transport path, whereby the interior space of the copying machine can be remarkably reduced.

The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention given with reference to the accompanying drawings.

Short description of the drawings

Fig. 1 is a vertical sectional front view showing a copying machine of the side manual sheet feeding type provided with a conventional manual sheet feeding mechanism;

Fig. 2 is a view similar to Fig. 1, showing a copying machine of the side manual sheet feeding type provided with a different conventional manual sheet feeding mechanism;

Fig. 3 is a perspective view showing guide plates and associated components according to a first embodiment of this invention;

Fig. 4 is a schematic perspective view showing a copying machine to which the present invention is applied;

Fig. 5 is a vertical sectional front view of the copying machine of Fig. 4;

Figs. 6A, 6B and 6C are side views showing the operation of the guide plates;

Fig. 7 is a perspective view showing guide plates and associated components according to a second embodiment of this invention;

Fig. 8 is a schematic side view showing guide plates according to a third embodiment of this invention ;

Fig. 9 is a block diagram;

Fig. 10 is a schematic sectional view showing sheet pressing devices according to a fourth embodiment of this invention;

Fig. 11 is a partially broken sectional view showing a fifth embodiment in which a switch is switched by means of a pivotable shutter member;

Fig. 12 is a schematic perspective view in which the arrangement shown in Fig. 11 is provided;

Fig. 13 is a schematic perspective view showing a modification of the fifth embodiment in which a switch is switched by means of a pivotable shutter member;

Fig. 14 is a perspective view showing guide plates and associated components according to a sixth embodiment in which a sheet is successively subjected to pressure from its reference side;

Figs. 15A, 15B, 15C and 15D are side views showing the operation of the arrangement of Fig. 14;

Figs. 16A and 16B are side views showing a seventh embodiment for subjecting a sheet to pressure step by step from its reference side.

Description of the preferred embodiments

Embodiments of this invention are explained below with reference to the accompanying drawings.

A first embodiment will now be described with reference to Figs. 3 to 6, in which Fig. 3 is a detailed perspective view showing the first embodiment, Fig. 4 is a schematic perspective view showing the external appearance of a copying machine to which the first embodiment is applied, Fig. 5 is a vertical sectional view Front view of the copying machine of Fig. 4, and Figs. 6A, 6B and 6C are schematic views showing the operation of the first embodiment.

A front loading type copying machine 1 is provided with a manual sheet insertion opening 2, a swingable manual sheet insertion tray 3 and a cassette 5 at the front. As shown in Fig. 5, a single sheet 6 is peeled off from the cassette 5 by a peel roller 7 and then fed to alignment rollers 10 by means of transport rollers 9. The sheet 6 is aligned in synchronism with an image formed on a drum 11 by the alignment rollers 10 and transported at a predetermined timing. Then, the image formed on the drum 11 is transferred to the sheet 6 by a charger 12 and the sheet 6 is separated from the drum 11 by a separation charger 13. The sheet 6 is fed to a fixing section 16 for fixing through a transport section 15. The sheet 6, which has a single image copied onto one side, is discharged by discharge rollers 17.

When a single image is to be copied onto the other surface of the sheet 6, while a substantial portion of the sheet 6 is being fed out by the discharge rollers 17, the discharge rollers 17 are reversed and the sheet 6 is fed downward through a guide flap 19 to a two-sided/multi-copy transport path 20.

When a multi-copy image is to be produced on one surface of the sheet 6, the sheet 6 is conveyed to the two-sided/multi-copy transport path 20 by means of the guide flap 19.

When a single image is to be copied on each surface after a multi-copy image is formed on one surface, the sheet 6 is guided through the gap between a pair of guide plates 21 and 22 and again transported by return rollers 23 toward the registration rollers 10.

A predetermined copying process is then carried out.

An arrangement for controlling the relationship between the manual sheet insertion at the front and a sheet transport for a two-sided/multi-copy will now be explained below with reference to Figs. 3 and 6.

In Fig. 3, the pair of upper and lower rectangular guide plates 21 and 22 explained in connection with Fig. 5 are rotatably supported on the main body of the copying machine 1 in parallel with each other by a pair of right and left pins 25. A manual sheet feed tray guide 26 is fixed to the main body so that its upper surface becomes flush with the upper surface of the manual sheet feed tray 3 which is opened outward (see Fig. 4). A lower guide 27 and an upper guide 29 are fixedly mounted on the main body at a position immediately adjacent to the manual sheet feed tray guide 26.

A pressure arm 31 is pivotally supported by pins 30 fixed to the main body at a position below the manual sheet feeding tray guide 26 and the lower guide 27. As shown in Fig. 6, the pressure arm 31 is arranged to move up and down by means of an eccentric cam 32 driven by a pulse motor or the like (see Fig. 9). Driven manual sheet feeding rollers 33 which are normally pushed upward are provided at an inner part of the pressure arm 31, and upward pushers 35 for pushing the guide plate 22 upward are provided at the inner end part of the pressure arm 31. The shaft of each roller 33 is supported so that it can move up and down and rotate about its axis in the slot 33a of the pressure arm 31.

As shown, drive rollers 36 for return transport are rotatably mounted on shafts extending from front to rear, and are engaged and disengaged by a clutch (not shown) via a drive source (not shown). The guide plate 22 is provided with openings 37 through which the respective drive rollers 36 are inserted. Driven rollers for return transport formed integrally with shafts 40 are opposed to the respective drive rollers 36. Brackets 41 each having a vertical slot 42 are mounted on the guide plate 21, and the opposite ends of each shaft 40 are fitted in the engagement slots 42 and are urged in the downward direction together with the driven rollers 39 by tension springs 43. Openings 45 through which the respective rollers 39 are inserted are formed in the guide plate 21. A roller release arm 46 having abutments under the shafts 40 is rotatably supported by a pivot 47 fixed to the guide plate 21, and one end 46a of the roller release arm 46 is formed to abut against the underside of a projecting portion 49 fixed to the main body. Driving manual sheet feed rollers 50 are arranged to enter through the upper guide 29 in a downward direction. The driving rollers 50 are opposed to the driven manual sheet feed rollers 33 and are rotated by operating a pulse motor or the like. A reference guide 57 for guiding the manually inserted sheet 6 is formed substantially perpendicular to the upper surface of the manual sheet insertion tray guide 26 on the right side thereof (when viewing Fig. 3).

Limiting devices for restricting the direction of a manually fed sheet are explained below.

The outer end portion of the guide plate 21 is bent upwards at substantially right angles to form a locking member 51. The locking member 51 is provided with a feeler lever 52 which comes into contact with the leading edge of the sheet when this leading edge strikes the locking part 51. A light interrupter 53 is combined with the sensing lever 52 in order to carry out a sensing operation. The upper guide 29 is equipped with a sensing lever 55 and a light interrupter 56 combined with it in order to detect the trailing edge of the manually inserted sheet 6.

As shown in Fig. 6, manual sheet feeding roller pairs each consisting of the driving roller 50 and the driven manual sheet feeding roller 33 are arranged within a region C through which the sheet 6 passes during the operation of a two-sided copy or a multi-copy. The boundary line D of the region C is indicated by a dash-dotted line.

The process of manual sheet insertion is explained below.

As shown in Fig. 6A, during a two-sided/multi-copying operation, the eccentric cam 32 is held at its minimum eccentric position and the pressure arm 31 remains at the lowermost position. The left ends of the respective guide plates 21 and 22, which are supported by the upward pressure pieces 35 provided at the inner end portion of the pressure arm 31, are positioned under the upper surface of the manual sheet insertion tray guide 26 with the locking member 51 intersecting the plane of the upper surface of the tray guide 26. In this position, the driven and driving return transport rollers 39 and 36 cooperate to perform a normal return operation. In particular, none of the driving and driven manual sheet feed rollers 50 and 33 arranged in the area C through which the sheet 6 is passed for the purpose of two-sided copying or multi-copying interferes with the sheet 6 during return.

In the above state, an operator determines that neither a two-side copying operation nor a multiple copying operation is active, and opens the manual sheet insertion tray 3, which also serves as a cover, in the direction indicated by the arrow in Fig. 4. Then, the operator inserts the sheet 6 through the manual sheet insertion opening 2 along the reference guide 57 in the direction of an arrow A until the leading edge of the sheet 6 abuts against the locking member 51 (the leading edge of the sheet 6 pushes the detector lever 52 to switch the device to a manual sheet insertion operation). Thus, a manual sheet insertion start signal is generated by a key (not shown).

In response to this signal, a control section causes the eccentric cam 32 to rotate through approximately 180º, thereby moving the pressure arm 31 upward. Thus, the guide plates 21 and 22 are pivoted upward about the pins 25 by means of the upward pressure pieces 35 (see Fig. 3) to keep the upper surface of the guide plate 22 slightly below the upper surface of the lower guide 27.

It should be noted that the dimensions of the pressure arm 31 and the eccentric cam 32 are selected so that all the driving return transport rollers 36 are positioned below the upper surface of the guide plate 22.

The driven manual sheet feeding rollers 33 are pressed by an upward pressing force against the associated driving manual sheet feeding rollers 50 over the manually fed sheet 6 which is in contact with the locking member 51, while the locking member 51 and consequently the guide plate 21 performs an upward movement. At this time, the nips between the rollers 33 and 50 are opposite to the guide gap defined between the guide plates 21 and 22. Since the end 46a of the roller release arm 46 is brought into contact with the projecting part 49, the roller release arm 46 simultaneously rotates about the pivot pin 47 to an inner side member 46b to move upwards, whereby the shafts 40 are moved upwards against the downward pressing force of the tension springs 43. Thus, the driven return transport rollers 39 move to a position above the underside of the guide plate 21.

When the above-mentioned eccentric cam 32 has rotated approximately 180°, a signal is output to the control section. In response to the signal, the control section operates the manual sheet feeding rollers 50 to feed the manually fed sheet 6 toward the inside at a predetermined speed.

Then, after the trailing edge of the sheet 6 is detected by the detector lever 55 and the photointerrupter 56, the sheet 6 is transported over a predetermined distance, and the driving and driven manual sheet feed rollers 50 and 33 are stopped. This movement brings the trailing edge of the sheet 6 into coincidence with the boundary line D of the above-described area C.

When the control section receives a signal indicating that the drive source for driving the manual sheet feeding rollers 50 is stopped, the control section then turns on a drive source for the eccentric cam 32 to cause it to rotate approximately 180°. As shown in Fig. 6C, the pressure arm 31 moves downward and is returned to the state explained in connection with Fig. 6A.

When the control section receives a signal indicating that the drive source for driving the eccentric cam 32 has been stopped (or when the control section counts a predetermined number of pulses), the control section operates the driving and driven return transport rollers 36 and 39 to transport the manually inserted sheet 6 in a direction substantially the same as the direction of the manual insertion is perpendicular (in the direction indicated by arrow B in Fig. 3). Then, the sheet 6 is again transported to an image forming area (including components such as the drum 11, the fixing section 16) by means of the return rollers 23 (see Fig. 5) and the registration rollers 10.

A second embodiment will now be explained with reference to Fig. 7.

In Fig. 7, the same reference numerals are used to designate elements having the same arrangement and function as those shown in Fig. 3, and explanation is omitted for the sake of simplification.

The second embodiment differs from the above-mentioned first embodiment in that the roller release arm 46 has a different configuration. Abutment arms 60 for abutting against the respective shafts 40 from below extend in opposite directions. The protruding part 49 shown in Fig. 3 as being attached to the main body may be omitted, and the end of the roller release arm 46 for abutting against the protruding part 49 may also be omitted. The pressure arm 31 extends so as to abut against the underside of each abutment arm 60.

In the above arrangement, since the pressure arm 31 moves the guide plates 21 and 22 upward, the extended end of the pressure arm 31 engages with the roller release arm 46 and moves it upward about the pivot pin 47, whereby a function similar to that of the first embodiment can be achieved.

Although in the first embodiment the initial position of the guide plates 21 and 22 is arranged below the manual sheet insertion tray guide 26, the positional relationship between them. Specifically, the pressure arm 31, the pins 30, the eccentric cam 32, etc. may be arranged above the manual sheet insertion tray guide 26, and the positional relationship between the driving and driven manual sheet insertion rollers may be reversed in the vertical direction. Accordingly, the guide plate 21 is moved downward to assume the position shown in Fig. 6B. Similarly, the positional relationship between the driving and driven return transport rollers 36 and 39 may be reversed vertically. Also with such an arrangement, it is possible to achieve the operation of manually inserting the sheet 6 as in the case of the first embodiment. In the first embodiment, although the guide plates 21 and 22 are loaded downward, they are pressed against the pressure arm 31 to be free from vibration. In the second embodiment, however, the guide plates 21 and 22 may be loaded upward to be pressed against the pressure arm arranged above the guide plates 21 and 22.

With reference to Fig. 8, a third embodiment is explained below.

In the third embodiment, the guide plates 21 and 22 are not integrally arranged but are arranged separately, and they are each pivotally supported by pins 62 and 65, each of which is pivotally supported by parallel links 61 and 62. The rotational operation of the parallel links 61 and 62 performs the function of the pressure arm 31 and the eccentric cam 32 to move the guide plates 21 and 22 up and down. It is also possible to apply and remove the release pressure to and from the driven return transport rollers. Although in the third embodiment the guide plates 21 and 22 are pivotally supported by each of the links 61 and 62, the guide plates 21 and 22 may be formed as an integral assembly and the pin 63 or 65 may be arranged on one side to pivotally support them.

According to any of the above-described first to third embodiments of the present invention, the conveying direction of a manually inserted sheet is restricted by restricting means 51 formed of a part of a guide means 21, 22, and the sheet 6 is then conveyed from a first conveying path 20 by means of the guide means 21, 22. Accordingly, it is possible to prevent the oblique conveying or erroneous conveying of the sheet 6, so that formation of images in a staggered manner can be prevented. Furthermore, since no special means is necessary and, for example, the restricting means 51 is formed of a part of the guide means 21, 22, it is possible to provide a conveying device of simple construction, small size and low cost.

In each of the above-described embodiments, the sensing lever 55 and the photointerrupter 56 used for positioning the sheet 6 are arranged on the outer side of the guide plate 21 and 22 (on the upstream side of the area C shown in Fig. 6). However, an equivalent device may be arranged in the center of the area C or on the inner side thereof. For example, when a reference point is arranged on the inner side, a plurality of pairs of manual sheet feeding rollers and a sensor may be provided to detect the leading edge of the sheet 6 reaching the vicinity of the inner reference point.

Although in each of the above embodiments, the guide plates 21 and 22 are moved up and down to move the driving and driven return transport rollers 36 and 39 into and out of the transport path for the sheet 6, the driving and driven rollers 36 and 39 may be moved independently.

Each of the above embodiments includes a control circuit, e.g., that shown in Fig. 9. In Figs. 3-8, the respective motors for operating the eccentric cam 32, the driving return rollers 36 and the driving sheet feed rollers 50 are not shown.

An arrangement for temporarily retaining the sheet 6 while the guide means are moved will now be explained in detail with particular reference to Fig. 6.

When the control section receives a signal indicating that the drive source for driving the manual sheet feeding drive rollers 50 has been stopped, the control section turns on the drive source of the eccentric cam 32 to cause it to rotate approximately 180°. As shown in Fig. 6C, while the pressure arm 31 moves downward, the guide plates 21 and 22 reach the position shown in Fig. 6A, but the shaft of the manual sheet feeding drive rollers 33 is located above the center of the pressure arm 31. As a result, the rollers 33 are pushed upward and pressed against the manual sheet feeding drive rollers 50 (this state corresponds to an intermediate state between the states shown in Figs. 6B and 6C).

When the pressure arm 31 reaches its lower end position, the upper end of the slot 33a forces the rollers 33 downward to the state shown in Fig. 6C against the upward urging force of the rollers 33. Thus, preparation for returning to the state shown in Fig. 6A is completed. Specifically, the manually inserted sheet 6 is first nipped between the rollers 50 and 33, and then, while being transported from the rollers 50 and 33 to the rollers 36 and 39, it is nipped between the rollers 50 and 33 and the rollers 36 and 39. Accordingly, the manually inserted sheet 6 is always held.

Then, the pressure arm 31 moves downward as shown in Fig. 6C, and the mechanism is returned to the state explained in connection with Fig. 6A. However, the sheet 6 is clamped between the driving and driven rollers 36 and 39 for return transport.

A temporary holding device according to the fourth embodiment will be described below with reference to Fig. 10. The same reference numerals are used to designate components having the same arrangement and function as those used in each of the above embodiments, and description thereof will therefore be omitted.

Each of the above-mentioned embodiments is adapted to continuously hold the manually inserted sheet 6 by means of the slots 33a of a selected length formed in the pressure arm 31. In the fourth embodiment, the sheet 6 is held on the guide plate 22 by evacuation.

The guide plate 22 has a plurality of holes 22a, and a bellows 60 is fixed to the underside of the guide plate 22 to enclose the holes 22a. A duct 61 extending from the bellows 60 is fixedly mounted to the copying machine 1, and an exhaust fan 62 is arranged in the outlet end of the duct 61. When this exhaust fan 62 is driven by a motor (not shown), the air in the duct 61 is discharged in the direction indicated by the arrow E in Fig. 10 to reduce the pressure in the duct 61. Thus, the sheet 6 is held on the guide plate 22 by evacuation via the openings 22a.

When the manually inserted sheet 6 is transported by means of the rollers 33 and 50 and the trailing edge of the sheet 6 reaches the boundary line D, the control section receives a signal indicating that the drive source for operating of the rollers 50 has stopped, and it operates the motor of the suction fan 62 to cause it to rotate, thereby holding the sheet on the guide plate 22. A short time after the suction fan 62 starts rotating, the control section turns on the drive source of the eccentric cam 32 to cause it to rotate approximately 180º. When the state shown in Fig. 6C is reached, the control section stops the drive source of the eccentric cam 32 and the motor of the suction fan 62 at the same time.

When the fourth embodiment is to be put into practice, the fine adjustment of the length of each slit 33a required in the above embodiments can be omitted. In addition, the fourth embodiment can be combined with any of the aforementioned embodiments.

As is clear from the foregoing, according to the fourth embodiment, while the aforesaid guide plates 21, 22 move in alignment with another transport path 20, the sheet 6 is temporarily held in position by holding means 33a, 33 or 62a. Accordingly, the sheet 6 is transported without the fear of being displaced from position, thereby improving the transport accuracy of the manually inserted sheet. The present invention can be applied, for example, to a two-sided/multi-copying machine equipped with the manual sheet insertion transport path 26 leading to a part of the return transport path in the direction substantially perpendicular thereto. With this arrangement, the return transport path 20 can also be used as a front manual sheet insertion transport path, so that significant space saving in the copying machine can be achieved. Furthermore, compared with conventional side manual sheet feeding type copiers, it is possible to reduce the space required to install the copier and also increase its efficiency.

A fifth embodiment, which includes transport devices provided on a closure element and a switch, is explained below.

According to Fig. 11, a manual sheet insertion opening is designated 121, and a manual sheet tray (a shutter member) 122 is pivotally supported by a shaft 123 so that it can rotate as indicated by arrow A. At the lower part (as viewed in Fig. 11) of the manual sheet tray 122, driven manual sheet insertion rollers 125 are arranged which are urged inward by spring means 126. A projection 127 is provided on one side of the lower end portion of the manual sheet insertion tray 122 and is brought into a horizontal open state (the position shown by a chain line) by driving manual sheet insertion rollers 129 provided on the main body of the copying machine being pressed against the driven rollers 125 and driven by a drive source motor. A member 130 for sensing the reference end (trailing edge) of the transfer paper P is held on the copying machine 1 at the outside of the position of the driving rollers 129, and an interrupter 131 is arranged to detect the reference end of the transfer paper P from the movement of the sensing member 130. A sensing element 132 for detecting whether the upper end of the manual sheet feeding tray 122 is open or closed is mounted on the copying machine 1. When the open state is detected, the manual sheet feeding prohibition command is executed and a command to allow feeding of a sheet from the cassette 5 is issued.

Guide plates 133 and 135 for guiding the transfer paper P are formed into a one-piece member, and support means 136a are formed at an inner end thereof, the support means 136a being pivotally supported by a pin 136 fixed to the copying machine 1. When the guide plates 133 and 135 are held in a horizontal position, the center plane between these below the upper surface of the manual blade insertion tray 122 in its open position. As long as the manual blade insertion tray 122 is open, the inlet into the center plane between the guide plates 133 and 135 is substantially flush with the guide surface of the open manual blade insertion tray 122.

A main body transport driving roller 137 is capable of being operated by a drive source motor and is rotatably mounted on the copying machine 1 in such a manner that its axis extends from the front to the rear of the machine 1. A pinch roller 139 is arranged opposite to the driving roller 137 above the guide plate 133 in such a way that it can move upward as the plate 133 swings. As a mechanism for moving the pinch roller 139 upward away from the guide plate 133, various mechanisms such as those shown in Figs. 3 and 7 can be used. For example, the pinch roller 139 can be moved upward by swinging the guide plate 133 and rotating a solenoid or the like. The pressure roller 139 may be mounted on an arm pivoted by the copier 1 so that the pivoting guide plate 133 moves the arm upward. In the arrangement shown in Fig. 11, a guide 140 is arranged on one side of the manual sheet insertion tray 122 to guide the side edge of the manually inserted sheet 6.

In the fourth embodiment having the above-described arrangement, when the manual sheet insertion tray 122 is opened opposite to the manual sheet insertion opening 121, the sensing element 132 is turned off to stop the peel roller 7 disposed in the cassette 5, thereby preventing feeding from the cassette 5. At the same time, the projection 127 pivots the integral guide plates 133 and 135 to bring the center plane between them into opposition to the upper surface of the manual sheet insertion tray 122. At this time, the main body driving transport roller 137 outward (downward) from the guide plate 135, and the pressure roller 139 projects from at least the lower surface of the guide plate 133 to a small extent. Consequently, the manually inserted transfer paper P can be smoothly inserted into the gap between the guide plates 133 and 135, and the driven manual sheet insertion rollers 125 press against the associated driving rollers 129.

When the transfer paper P is manually fed over the tray 122 along the guide 140 in the direction of an arrow B in Fig. 11, the leading edge of the transfer paper P presses the sensing element 130 and the interrupter 131 is turned on to detect the insertion of the transfer paper P. In response to the signal indicating the insertion, the driving manual sheet feeding rollers 129 are rotated to transport the transfer paper P. When the trailing edge (reference end) of the transfer paper P passes the sensing element 130 and the sensing element 130 inclines downward, the interrupter 131 is turned off, and in accordance with the interrupter off signal generated at that time, the reference end of the transfer paper P is stopped at a main body conveyance reference line 141 of the transfer paper P.

When the manual sheet insertion tray 122 is closed, the guide plates 133 and 135 are returned to the horizontal position, and the rollers 125 and 129 clamp the transfer paper P, and at the same time, the driven manual sheet insertion rollers 125 move away from the transport path. The sensing element 132 is turned on, and in accordance with the on signal generated at this time, the main body driving transport roller 137 is rotated to transport the manually inserted transfer paper P for the purpose of image formation.

As shown in Fig. 13, the manual sheet insertion tray 122 may be integrally formed with the shaft 123 so that the shaft 123 can be rotated forward or backward by means of a motor 142 to achieve the above manual sheet insertion and feeding of the sheets from the main body.

As is clear from the foregoing, according to the embodiment shown in Figs. 11 to 13, closing of the above-mentioned manual sheet insertion tray 22 is used to effect the release of the manual sheet insertion devices 25 and 29, the displacement of the guide means 33, 35 to a first transport path 19, the pressing of the transport means 37, 39 and the actuation of a sheet insertion device 3. Accordingly, it is possible to remarkably simplify the construction of a sheet transport device of the manual front sheet insertion type and also to greatly reduce the cost. Since a second transport path 22 for manual sheet insertion is substantially flush with the first transport path 19 for transporting the sheet P, it is possible to reduce the required installation space without the need to increase the height of the apparatus. Furthermore, since a manual sheet insertion opening 21 can be covered, dangers can be prevented and the external appearance is improved.

A sixth embodiment, which is designed to subject the sheet 6 to pressure successively from the reference end side, will be described below.

Referring to Figures 14 to 16, the brackets 41 are secured in place and a roller release arm 246 is supported by the pin 47 for pivotal movement with respect to the brackets 41. Brackets 242, each of which has a rectangular configuration in cross-section, are formed on opposite sides of one end of each arm 246, respectively, and vertically extending slots 242a are formed in the respective legs of the brackets 242. The shafts 40 of the driven return transport rollers 39 are guided through the associated slots 242a so as to be restricted in the transverse direction and slidable in the vertical direction. The outer end 246a of the roller release arm 246 is arranged to abut against the underside of the projecting member 49 fixed to the main body of the copying machine 1. The shafts 40 and the driven rollers 39 are urged downward by the associated tension springs 43, and the guide plate 21 has the openings 45 through which the associated rollers 39 project from the guide plate 21.

The process of manual sheet insertion is explained below.

As shown in Fig. 15A, during a two-sided/multi-copying operation, the eccentric cam 32 is held at its minimum eccentric position and the pressure arm 31 is located at the lowermost position. The left ends of the respective guide plates 21 and 22, which are supported by the upward pressure pieces 35 provided at the inner end portion of the pressure arm 31, are located under the upper surface of the manual sheet insertion tray guide 26 with the locking member 51 crossing the plane of the upper surface of the tray guide 26. In this position, the driven and driving return transport rollers 39 and 36 cooperate to perform a normal return operation. Above all, none of the driving and driven manual sheet feed rollers 50 and 33 arranged in the area C used for the two-sided/multi-copy transport interferes with the sheet 6 during a return.

In the above state, an operator determines that neither a two-sided copying operation nor a multiple copying operation is active, and inserts the sheet 6 along the reference guide 57 in the direction of arrow A of Fig. 14 until the leading edge of the sheet 6 abuts the locking member 51. On In this way, a manual sheet insertion start signal is generated by a button (not shown).

In response to this signal, the control section causes the eccentric cam 32 to rotate through approximately 180º, thereby moving the pressure arm 31 upward. The guide plates 21 and 22 are rotated upward about the pins 25 by means of the upward pressure pieces 35 (see Fig. 14) to keep the upper surface of the guide plate 22 slightly below the upper surface of the lower guide 27. It should be noted that the dimensions of the pressure arm 31 and the eccentric cam 32 are selected so that all the driving return transport rollers 36 are located below the upper surface of the guide plate 22. The driven manual sheet feed rollers 33 are pressed by an upward pressure force against the associated driving rollers 50 over the manually inserted sheet 6 in contact with the locking part 51, whereby the locking part 51 and thus the guide plate 21 perform an upward movement. Since at the same time the end 246a of the roller release arm 246 is brought into contact with the projecting part 49 and the inner part of the roller release arm 246 is moved upward, the shafts 40 are thereby moved downward against the acting force of the tension springs 43. Thus, the driven return transport rollers 39 are displaced to a position above the underside of the guide plate 21.

When the aforementioned eccentric cam 32 has rotated approximately 180°, a rotation end signal is transmitted to the control section. In response to the signal, the control section operates the manual sheet feed rollers 50 to transport the manually fed sheet 6 toward the inside at a predetermined speed (see Fig. 15B). Then, after the trailing edge of the sheet 6 is detected by the detector lever 55 and the interrupter 56, the sheet 6 is transported over a predetermined distance, and the driving and driven manual sheet feed rollers 50 and 33 are stopped. This movement brings the trailing edge of the blade 6 into line with the boundary line D of the region C described above. The state of the blade 6 is as shown in Figs. 15C and 15D.

When the control section receives a signal indicating that the drive source for driving the manual sheet feed driving rollers 50 has been stopped, the control section turns on the drive source for the eccentric cam 32 to cause it to rotate approximately 180°. As shown in Fig. 15C, each shaft 40 is positioned at the lower sides of the respective slots 242a and inclined along the inclined axis of the lower sides. The driven return transport rollers 39 located next to the reference end of the sheet 6 (the boundary line D), then the rollers 39 located closer to the reference end after the aforementioned rollers 39, and so on, are brought into printing engagement with the sheet 6 in sequence. During this process, each shaft 40 gradually rises from the lower part of the left-hand slot 242a (as viewed in Figs. 15A to 15D).

In a state where the left side roller 39 is pressed against the sheet 6, the shaft 40 is slightly separated from the lower part of the two slits 242a as shown in Fig. 150. In this way, the sheet 6 can be pressed in an appropriate manner one after another from the reference edge part by suitably selecting the distance between the opposing slits 242a, the inclination of the roller release arm 246 during a downward movement, the length of each slit 242a and the tension force of each tension spring 43. With this arrangement, since even a wavy sheet 6 is pressed in succession from its reference edge part, it is possible to accurately position the sheet 6 along the conveying path (or the guide plate 21). When the drive source of the eccentric cam 32 is turned off, the drive source of the rollers 36 is turned on, to transport the sheet 6 in a direction substantially perpendicular to the direction of manual sheet insertion.

A seventh embodiment of the present invention will be described below with reference to Figs. 16A and 16B. In Figs. 16A and 16B, the same reference numerals are used to denote components having substantially the same arrangement and operation as those shown in Fig. 15, and an explanation thereof will not be given.

A frame 360 is fixed on the upper guide plate 21, and a shaft 361 is horizontally supported by the frame 360 for rotation about its axis. Opposing slots 363 and 365 are formed in the front and rear portions of the frame 360 at a position below the shaft 361, respectively. A shaft 362 is supported by the slots 363 and 365 so as to be axially restricted and vertically slidable, and three return transport rollers 339 are mounted on the shaft. Abutment pieces 366, each of which has an approximately circular opening 367 on the head side and a slot 369 communicating therewith on the bottom side, are provided in the frame 360. Eccentric cams 370 and 371 are attached to the shaft 361 and engage with the openings 367 of the respective abutments 366. The shaft 362 abuts the bottom part of each abutment 366.

The shaft 361 is driven by a motor 372 held on the rear part of the frame 360.

The eccentricities of the cams 370 and 371 are selected so that, as shown in Fig. 16B, during a downward movement 36 of the guide plate 21, the driven return transport roller 339, which is arranged on the side of the reference edge of the sheet 6 (the left side in the drawing), initially engages with the Sheet 6 comes into printing. In particular, the motor 372 rotates the shaft 361 and thus the eccentric cams 370 and 371 through 180º at a time which is time dependent on the eccentric cam 32 shown in Figs. 15A to 15D.

Although each of the embodiments shown in Figs. 15 and 16 uses as the reference end the left side of the sheet 6 as viewed in the accompanying drawing, the reference end may be set in the inside of the area C used in a two-side/multi-copy transport. When this arrangement is applied to the embodiment of Fig. 15, the rollers 39 can be pressed against the sheet 6 one by one from the inside by selecting the length or position of each slot 242a of the carrier shown in Figs. 15A to 15D. In the embodiment of Figs. 16A and 16B, it is sufficient to select the eccentricities of the eccentric cams 370 and 371 appropriately.

As is clear from the foregoing, in the embodiment of Figs. 14 to 16, a sheet 6 is transported to a first transport path 26 by means of first transport means 33, 50 and then to a second transport path 20 by means of second transport means 36, 39. During this operation, the second transport means 36, 39 come into pressure contact with the sheet 6 on the second transport path 20 from the reference edge side thereof one after another. Consequently, even if the sheet 6 has wavy or sagging parts, the slack is forced from the reference edge to the sides other than the reference edge, whereby the sheet 6 can be accurately positioned on the second transport path 20. It is therefore possible to provide an image forming system capable of forming a faithful image and free from sheet jam.

In addition, because the first transport path 26 and the first transport means 33, 50 are arranged as a front loader type of manual sheet insertion mechanism, no space for side manual sheet insertion is required. Accordingly, it is possible to greatly improve the ease of installation of the image forming system 1.

While the present invention has been described with reference to what are presently considered to be the preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. On the contrary, the present invention is intended to cover various modifications and equivalent arrangements included within the scope of the appended Patent claims fall.

Claims (19)

1. A device for transporting a sheet (6; P), which comprises - first guide means (21, 22; 133, 135) forming a first transport path for guiding said sheet to an image forming section (10 - 13), - first transport means (36, 39; 137, 139) for transporting the said sheet along the said first transport path - second guide means (26, 27, 29; 122, 140) forming a second transport path for guiding said sheet in a direction transverse to said first transport path, said first and second transport paths alternatively being aligned or non-aligned in the height direction, - second transport means (33, 50; 125, 129) for transporting the said sheet along the said second transport path towards the said first guide means and - Control means for switching said first and second transport paths so that they are aligned for transporting said sheet from said second guide means to said first guide means as soon as said sheet is introduced through said second guide means. 2. An apparatus according to claim 1, in which said first guide means (21, 22; 133, 135) are adjusted to align said first transport path with said second transport path. 3. An apparatus according to claim 1, in which said second guide means are adjusted to align said second transport path with said first transport path. 4. An apparatus according to claim 1, wherein said control means are arranged to operate the control in response to the input of a manual sheet insertion start signal. 5. An apparatus according to claim 4, further comprising a manual sheet insertion start button. 6. An apparatus according to claim 2, further comprising means (30-15 32, 35; 62, 63, 65; 127) for moving said first guide means (21, 22; 133, 135) up and down, said moving means being operated in response to a manual sheet insertion signal. 7. A device according to claim 6, in which said movement means (30 - 32, 35) comprise a rotating eccentric cam (32). 8. An apparatus according to claim 6, in which said second transport path is provided with a locking device (51) for stopping said inserted sheet. 9. A device according to claim 8, in which said locking device (51) is arranged on said first guide means (21, 22) and is arranged to move out of its locking position when said first guide means move upwards. 10. An apparatus according to claim 6, in which said second transport means (33, 50; 125, 129) are provided with a rotating member (33; 125) which moves up and down when said first guide means (21, 22; 133, 135) up and down, said rotating member being actuated to transport said sheet (6) from said second guide means (26, 27, 29; 122, 140) to said first guide means as soon as said first and second transport paths are in alignment. 11. An apparatus according to claim 2, wherein said first transport means includes a pair of vertically arranged members (36, 39; 137, 139), said vertically arranged members being displaced toward and away from each other with the downward and upward movements of said first guide means (21, 22; 133, 135). 12. An apparatus according to claim 11, wherein, once said first guide means (21, 22; 133, 135) move upwards and said first and second transport paths are aligned, said first transport means (36, 39; 137, 139) move out of said first transport path. 13. An apparatus according to claim 2, further comprising means (33a; 22a, 60 - 62) for holding said sheet (6) to said first guide means (21, 22; 133, 135) while said first guide means are moved. 14. An apparatus according to claim 2, further comprising - closure means (122) which are selectively operable to open and close a manual sheet insertion opening (121), and - dependently coupled elements (127) for moving said first guide means up and down in accordance with the opening and closing of said closure means, - said second transport means (125, 129) are arranged in said second transport path and are operable to move towards and away from each other when said closure means open and close. 15. An apparatus according to claim 11, in which said first transport means (36, 39) comprise a plurality of members (39) arranged in an axial direction, said first transport means, when raised, being inclined so that the member (39) closest to said second guide means (26, 27, 29) is closer to said first transport path than the other members. 16. An apparatus according to claim 15, in which, as said first transport means (36, 39) move downwards, said members (39) begin to subject said sheet (6) to pressing in succession from the member closer to said second guide means (26, 27, 29). 17. An image forming apparatus comprising a device for transporting a sheet according to any preceding claim and an image forming section (10-13) for forming an image on said sheet (6) guided by said first guide means (21, 22; 133, 135). 18. An image forming apparatus according to claim 17, in which said first guide means (21, 22; 133, 135) are arranged to return a sheet (6) on which an image is formed in said image forming section (10-13) to said image forming section. 19. An image forming apparatus according to claim 18, in which said second guide means (26, 27, 29; 122, 140) are arranged to guide a sheet (6) fed from a front side of said image forming apparatus toward said first guide means (21, 22; 133, 135).