Sheet feeding apparatus

Abstract: The present invention relates to a sheet feeding apparatus having a stacking tray (13) on which sheets (S) are stacked, a first sheet feeding rotary means (16) for supplying a sheet from the stacking tray (13), and a second sheet feeding rotary means (17) for feeding the sheet from the first sheet feeding rotary means (16) toward a predetermined processing position. The feeding apparatus has a control means for rotating the second sheet feeding rotary means (17) for a predetermined time during the feeding of a preceding sheet, for stopping the preceding sheet with a trailing end thereof being retained in a nip of the second sheet feeding rotary means and then for rotating the second sheet feeding rotary means with a leading end of a next sheet being inserted into the nip to feed the preceding and next sheets simultaneously.

Description: The present invention relates to a sheet feeding apparatus according to the preamble of claim 1; more particularly, it relates to a sheet feeding apparatus such as an original feeding apparatus used with a copying machine, reader and the like, which can simultaneously rest a plurality of sheets on a predetermined processing device. Fig. 1A shows an example of an image forming system comprising a conventional sheet feeding apparatus. In Fig. 1, the image forming system comprises a frame or body 100 and a platen 101 acting as an image reading portion. An sheet feeding apparatus 200 is disposed above the platen. The sheet feeding apparatus 200 comprises a stacking tray 201 on which a plurality of sheets or originals S′ are stacked (original stack S), a separating portion 202 for separating the original S′ from the original stack S on the stacking tray 201 one by one, feed rollers 203 for feeding the original S′ separated by the separating portion 202 toward the platen 101, a sensor 204 disposed between the feed rollers 203 and the separating portion 202 and adapted to detect the original S', a whole-surface belt 205 for setting the original S' fed from the feed rollers 203 on the platen 101, an ejector roller 207 for ejecting the original S' from the platen 101 onto a sheet discharge tray or ejector tray 206. In the above image forming system, the original stack S is set on the stacking tray with the images thereof turned upside (refer to Fig. 1A). When a copy start signal is applied to the apparatus, the separating portion 202 is rotated to separate a lower-most original S' from the original stack S and to feed it until a leading end of the original abuts against the feed rollers 203 (refer to Fig. 1B). Then, the feed rollers 203 and the whole-surface belt 205 are rotated normally so that the original S′ is fed toward the platen 101; the rollers 203 and the belt 205 are stopped when a trailing end of the original S′ leaves the feed rollers 203 (refer to Fig. 1C). Then, the whole-surface belt 205 is rotated slightly reversely until the trailing end of the original S′ abuts against the feed rollers 203, and then, the belt is stopped (refer to Fig. 1D). Thereafter, the separating portion 202 is rotated to separate a next or second original S′ and to feed it until a leading end of the second original abuts against the feed rollers 203 (refer to Fig. 1E). Then, the feed rollers 203 and the whole-surface belt 205 are again rotated normally so that the second original S′ is fed toward the platen 101; the whole-surface belt 205 is stopped when the second original S′ reaches a predetermined position on the platen 101 (refer to Fig. 1F). In this way, two originals S′ are rested or arranged side by side on the platen 101. Thereafter, when images of these originals S′ are read (refer to Fig. 1G), the images of two originals S′ are copied or printed on one surface of a single copying sheet. After the reading of the images has been finished, the whole-surface belt 205 and the ejector roller 207 are rotated normally to eject or discharge the originals S′ on the platen 101 onto the discharge tray 206 (refer to Fig. 1H). However, as apparent from Fig. 2 showing a nip between the feed rollers 203 in an enlarged scale, it is difficult that the leading end of the second original S′ is abutted against the trailing end of the lowermost or first original S′, and thus, a clearance corresponding to a width X of the nip will be created between these ends of the two originals. Consequently, a clearance corresponding to the width X is also created between two originals S' rested on the platen 101, which leads in the drawback in the copying operation. For example, as shown in Fig. 3, assuming that the size of the original S′ is ℓ₁ and the clearance between two originals is ℓ₂, when the images of these originals are copied on a copying sheet having a size larger than the original by two times or twice, since the first original S′ is shifted by a distance ℓ₂ from an image reading area, an image portion included in a hatched area (having a width ℓ₂) of the first original S′ will disappear from the copied image on the copying sheet. In document US-A-4 731 637 there is disclosed a generic sheet feeding apparatus. This sheet feeding apparatus comprises paired opposite roller means for feeding a first sheet and stopping the sheet with a trailing end thereof projecting out of the nip portion defined by the paired opposite roller means. Namely, the trailing end of said first sheet projects to a position of the sheet feeding path closely behind a vertical gate which is retractably insertable into the feeding path to engage and register the front edge of a second sheet fed next to the first sheet. Upon raising of the registration gate both sheets could be advanced to the desired registration position on the platen where they may be imaged. However, by means of the arrangement of such a sheet feeding apparatus a lack or disappearance of a portion of the images may occur. It is the object of the present invention to provide a sheet feeding apparatus and an image forming apparatus using this sheet feeding apparatus which can read images of a plurality of sheets arranged side by side and can print the read images on a single recording medium without the lack of disappearance of a portion of the images. This object is achieved by means of the features indicated in claim 1. According to these features, the control means rotating the paired opposed roller means are means for rotating the paired opposed roller means for a predetermined time during a feeding of a first sheet, for stopping the first sheet with a trailing end thereof being retained in a nip of the paired opposed roller means, for rotating the first rotary means to feed a second sheet into a wedged cavity defined by the peripheral surfaces of the roller means and for subsequently rotating the paired opposed roller means with a leading end of the second sheet being inserted into the nip to feed the first and second sheets simultaneously. Due to this arrangement it is possible to further minimize the clearance between the sheets, thereby eliminating or minimizing the lack of the image information. Furthermore, unlike the conventional technique, the driving mechanism can be simplified and the operating time therefor can be reduced to shorten the whole processing time. Preferable embodiments of the invention are defined in the claims 2 to 10. In the following the invention is further illustrated by embodiments with reference to the enclosed figures. Figs. 1A to 1H are elevational views of a conventional original feeding apparatus, for explaining the operation thereof; Fig. 2 is an enlarged view showing a nip between feed rollers of the conventional sheet feeding apparatus; Fig. 3 is a plan view of images printed on a recording medium by the conventional sheet feeding apparatus; Fig. 4 is an elevational view of an sheet feeding apparatus and an image forming system, according to a first embodiment of the present invention; Figs. 5A to 5F are elevational views of the sheet feeding apparatus according to the present invention, for explaining the operation thereof; Fig. 6A is an enlarged view of a nip between feed rollers of the apparatus of Fig. 4, Fig. 6B is an enlarged view of a nip between feed rollers according to another embodiment; Fig. 7 is a block diagram of a control system for the sheet feeding apparatus according to the present invention; Fig. 8 is an elevational view of an image forming system according to another embodiment of the present invention; Figs. 9A to 9C are elevational views of an sheet feeding apparatus used with the image forming system of Fig. 8, for explaining the operation thereof; Fig. 10 is a block diagram of a control system of the image forming system of Fig. 8; Fig. 11 is a flow chart showing the controlling contents of the control system; Fig. 12 is a plan view of images printed on a recording medium by the sheet feeding apparatus according to the present invention; Fig. 13 is an explanatory view showing an alteration; Fig. 14 is a schematic sectional view of an sheet feeding apparatus of an image forming system to which the present invention is applied, according to a further embodiment of the present invention; Figs. 15A to 15G are schematic elevational views of the sheet feeding apparatus and the image forming system, for explaining the operation thereof, where images are printed on a single surface of a recording medium; Figs. 16A to 16D are schematic elevational views of the sheet feeding apparatus and the image forming system, for explaining the operation thereof, where images are printed on both surfaces of a recording medium; Fig. 17 is a block diagram of a control system of the image forming system; Fig. 18 is a flow chart showing the controlling contents of the control system; Fig. 19 is an elevational view of the sheet feeding apparatus in an alterative form; Figs. 20A to 20E are schematic elevational views of the sheet feeding apparatus of Fig. 19, for explaining the operation thereof, where images are printed on a single surface of a recording medium; Figs. 21A to 21D are schematic elevational views of the sheet feeding apparatus of Fig. 19, for explaining the operation thereof, where images are printed on both surfaces of a recording medium; Fig. 4 is a schematic sectional view of a copying machine incorporating an sheet feeding apparatus according to a first embodiment of the present invention, Figs. 5A to 5F are views for explaining the operation of the sheet feeding apparatus, and Fig. 6 is an enlarged view of a nip between feed rollers of the apparatus. In these Figures, the copying machine comprises a frame or body 10 and a platen 11 acting as an image reading portion. An sheet feeding apparatus 12 is disposed above the platen. The feeding apparatus 12 comprises a stacking tray 13 on which a plurality of sheet S′ are stacked (sheet stack S), first rotary means having a separating portion 14 (conveying roller 14a and separating belt 14b) for separating the sheets (in the following designated as "originals") S′ from the original stack S on the stacking tray 13 one by one, a substantially U-shaped guide 15 for guiding the separated original S′ to the platen 11, second rotary means or feed rollers 16 arranged at an appropriate position along the guide 15, for feeding the original S′ toward the platen 11, and a whole-surface belt 17 for setting the original S' at a predetermined position on the platen 101. At a downstream side of the stacking tray 13, there are arranged a semi-circular sheet feed or supply roller 18 and a sensor 19 for detecting a leading end of the original S′. Further, the conveying roller 14a of the separating portion 14 is rotated in an anticlockwise direction (Fig. 4) and the separating belt 14b is disposed adjacent to the conveying roller 14a and is also rotated in an anti-clockwise direction. At an upstream side of the feed rollers 16 along the guide 15, there is arranged a sensor 20 for detecting the passage of the original S′. Further, the whole-surface belt 17 is constituted by a driving roller 17a disposed at one end (left end in Fig. 4) of the platen 11, a driven roller 17b disposed at the other end (right end in Fig. 4) of the platen 11, a conveying belt 17c extending between and engaged by these rollers 17a, 17b. One end of a driving motor 21 is connected to a driving shaft 17a′ of the driving roller 17a so that the conveying belt 17c can be rotated in a direction shown by solid arrows in Fig. 4 by means of the driving motor 21. Incidentally, a clock plate 22 is connected to the other end of the driving shaft 21a and a photo-interrupter 23 is disposed near the clock plate 22. The photo-interrupter 23 controls a moving amount of the conveying belt 17c by counting the number of slits formed in the clock plate 22. Further, at the other end of the platen 11, there are arranged a substantially U-shaped guide 23 and an ejector roller or sheet discharge roller 24, so that the original S′ on the platen 11 can be ejected or discharged onto a sheet discharge tray 25 disposed above the conveying belt 17c. At an appropriate position along the guide 23, there is arranged a sensor 26 for detecting the original S′. Next, an operation of the copying machine with the original feeding apparatus will be explained. Now, an example that two originals S′ are simultaneously rested on the platen 11 will be described. (1) The originals are stacked on the stacking tray 13 with images thereon turned upside. (2) By depressing a copy start button (not shown), the supply roller 18 and the separating portion 14 are rotated to separate the lowermost original from the original stack and to feed it toward the feed rollers 16. (3) When a predetermined time is elapsed after a leading end of the original has passed through the sensor 20, the separating portion 14 and the roller 18 are stopped. In this way, the lowermost or first original is stopped in such a manner that the leading end of the original is abutted against the feed rollers 16 and a predetermined loop is formed in the original (Fig. 5A) to correct the skew-feed of the original. (4) When the separating portion 14 and the roller 18 are stopped, the feed rollers 16 and the whole-surface belt 17 are rotated normally in the direction shown by the arrow to convey the original toward the platen 11. (5) When a trailing end of the original has passed through the sensor 20 and reaches the nip between the feed rollers 16, the rollers 16 and the belt 17 are stopped (Fig. 5B). Now, the feeding amount of the original is controlled by counting the number of the slits of the clock plate 21 by means of the photo-interrupter 22 to seek the original advancing amount from when the leading end of the original has passed through the sensor 20. Incidentally, on the basis of the counted value, when it is judged that the trailing end of the original reaches near the stopping position, the advancing speed of the original is decreased (by reducing the supply of the voltage to the driving motor), thus facilitating the positioning of the original. (6) When the trailing end of the first sheet or original is pinched by the nip between the feed rollers (Figs. 5B and 6A), the roller 18 and the separating portion 14 are rotated again to feed a next or second original in the same manner as the above step (3). As a result, the second sheet or original is stopped in such a manner that the leading end of the original is abutted against the feed rollers 16 and a predetermined loop is formed in the original (Fig. 5C). As apparent from Fig. 6A, in this case, since the trailing end of the first original is pinched between the nip, a distance or clearance Y between the trailing end of the first original and the leading end of the second original will be smaller than the distance X described with respect to Fig. 3. Further, by setting the stopping position of the trailing end of the first original to a further upstream of the nip, the distance Y can be further reduced or eliminated. Since the second original tends to invade into the nip due to the reaction force of the loop, if the trailing end of the first original is protruded from the nip toward the upstream side thereof, the second original is guided by a wedged cavity defined by the peripheral surfaces of the feed rollers 16 to abut against the trailing end of the first original (Y = 0) (Fig. 6B). When the rollers 16 are rotated, the second original enters into the nip by the reaction force of the loop. (7) When the separating portion 14 and the roller 18 are stopped, the rollers 16 and the belt 17 are rotated normally again to feed two (first and second) originals toward the platen 11 (Fig. 5D). (8) When the trailing end of the second original has passed through the sensor 20 and reaches a predetermined position on the platen 11, the rollers 16 and the belt 17 are stopped (Fig. 5E). Also, in this case, the feeding amount of the originals is controlled by counting the number of slits of the clock plate 21 by means of the photo-interrupter 22. In this way, the two originals are rested on the platen 11 with a minute distance therebetween. (9) After the originals has been rested on the platen, an optical system (not shown) provided in the copying machine 10 starts a scanning operation. The scanning operation is continuously performed through the first and second originals. In synchronous with this scanning (reading) operation, a single sheet (recording medium) having a size equal to a total length of the first and second originals is fed from a cassette 301 by means of a supply roller 302. The sheet is stopped by regist rollers 303 and is fed in synchronous with a position of developed images formed on a photosensitive drum 304 (on which images of the first and second originals read are projected). As a result, the images of two originals are printed on the single copy sheet. By repeating such operations, a desired number of copies can be obtained. Incidentally, in Fig. 4, the reference numeral 305 denotes a fixing device, and 307 denotes a sheet discharge tray. (10) After the reading operation, the belt 17 and the roller 24 are rotated to eject the two originals on the platen onto the tray 25 (Fig. 5F). The above cycles are repeated until there is no original on the tray 13. In this way, it is possible to rest a plurality of originals on the predetermined position with a minimized distance therebetween by stopping the trailing end of the preceding original into the nip and by abutting the leading end of the next original against the trailing end of the preceding original. In the above steps (4) and (5), while the feeding speed of the first original from the position where the loop is formed in the original to the position where the trailing end of the original is pinched between the nip was the same as the normal original feeding speed, such speed may be delayed to enhance the accuracy for positioning the trailing end of the original in the nip. Further, the feeding speed of the first original may be delayed after the trailing end of the first original has just passed through the sensor 20, so that the accuracy for positioning the trailing end of the original in the nip can be improved. In the above embodiment, while the sheet feeding apparatus 12 included the separate or discrete stacking tray 13 and discharge tray 25, the apparatus may be designed so that the read original S' is returned to the same stacking tray 13. Further, while an example that two originals S' are rested on the platen 11 and printed on a single recording medium was explained, three, four or more originals S' may be rested on the platen 11 and copied on a single recording medium. Further, while an example that images of a plurality of originals S′ are printed on one surface (front surface) of a single recording sheet (single-side printing) was explained, images of a plurality of originals S′ may be printed on the other surface (back surface) of the single recording medium by turning over the recording medium in the copying machine. In addition, while the present invention was applied to the copying machine, it may, of course, be applied to a laser printer, image reader (reading apparatus) and the like. Now, a double-sided printing copying machine will be explained with reference to Fig. 8. Sheets (recording mediums) stacked in an upper cassette 400 are separated one by one by means of a separating claw and a supply roller 401 and each separated sheet is fed to regist rollers 406. On the other hand, sheets stacked in alower cassette 402 separated one by one by means of a separating claw and a supply roller 403 and each separated sheet is fed to the regist rollers 406. A manual sheet insertion guide 404 is provided for introducing a sheet one by one to the resist rollers 406 through rollers 405. A sheet stacking device (deck type) 408 is provided with an intermediate plate 408a which can be lifted and lowered by means of a motor and the like, so that sheets stacked on the intermediate plate can be separated one by one by means of a supply roller 409 and a separating claw to be fed to conveying rollers 410. The reference numeral 412 denotes a photosensitive drum; 413 denotes a reading optical system; 414 denotes a developing device; 415 denotes a transfer charger; and 416 denotes a separating charger. These elements 412 - 416 constitutes an image forming portion. The reference numeral 417 denotes a conveying belt for conveying the sheet on which the image was formed; 418 denotes a fixing deivce; 419 denotes conveying rollers; and 420 denotes a flapper. The sheet on which the image was formed is directed to ejector rollers are sheet discharge rollers 421 by the flapper 420 and then is fed to a sorter 422. Incidentally, in place of the sorter, an ejector tray may be provided. The reference numeral 430 denotes an automatic original feeding apparatus wherein the original is positioned one by one on a platen 431 and is read by the optical system. With respect to a single original positioned on the platen, an image is formed on the photosensitive drum in accordance with the number of copies which is set, and a plurality of sheets to be copied are fed from either cassette 400 or 402 or deck 408 whenever the image is formed on the photosensitive drum. The registration between the image on the photosensitive drum and the sheet is effected by the regist rollers 406. When the desired number of copies are obtained, the originals are discharged from the platen, and next originals are positioned on the platen. And, the cycle is repeated in the same manner as described above. An intermediate tray 500 once stocks the sheets on which the images were formed, when the images are to be copied on both surfaces of each sheet (double-sided print) or when the images are superimposed on the single surface of each sheet (multi-print). The reference numeral 501 denotes conveying rollers; 502 denotes a conveying belt; 503 denotes a flapper; 504 denotes a conveying belt; and 505 denotes conveying rollers. When the double-sided or both face print is effected, the sheet is introduced into the intermediate tray 500 through a path 506 with the imaged surface thereof turned upside. On the other hand, when the multi-print is effected, the sheet is introduced into the intermediate tray 500 through a path 507 with the imaged surface thereof turned downside. The sheets stacked on the intermediate tray 500 are separated and re-fed one by one from the bottom by means of auxiliary rollers 509, 510 and a pair of reversible separating rollers 511. The sheet re-fed is directed to the image forming portion through conveying rollers 513, 514, 515, rollers 410 and the regist rollers 406. After the images are formed on the sheet, the sheet is ejected as mentioned above. With respect to the original rested on the platen, the single-sided printing is effected in accordance with the number of copies which is set, and the printed sheets are stacked on the intermediate tray 500. Thereafter, the original is turned over, and then is again introduced onto the platen. The image of the original is read by times equal to a desired number of copies to be obtained. The read image is printed on the sheet fed whenever the reading is effected. The finished sheets are assorted by the sorter 422 with a proper page sequence. On the other hand, in some cases, one set of copies are formed whenever the original is circulated by the automatic original feeding apparatus. In this case, since, even when a plurality of same copies are to be obtained, a group of copies with the proper page sequence can be obtained, a desired number of assorted copies can be obtained without any sorter. When the double-sided printing is effected according to this method, the images on both surfaces of a single original are continuously read and are continuously printed on the front and back surfaces of a single sheet, and then the original is ejected. Thereafter, regarding the both surfaces of the next and other originals, the same cycles are repeated, thus obtaining a group of assorted copies on both surfaces of which the images are formed. While the present invention was explained with respect the specific embodiment thereof, it is not limited to such embodiment. For example, in positioning the original, the counting of the timer may be started in accordance with the original size information after the leading end of the original has been detected by the sensor 20 (disposed at the downstream side of the rollers 16) or may be started from when the rollers 16 are rotated. Next, the countermeasure to the clearance between the first and second originals which may be created by the original feeding apparatus of Figs. 4 - 8 will be explained with reference to Figs. 9 to 13. Since the feeding control regarding the originals S′ effected by means of the sheet feeding apparatus 12 is substantially the same as mentioned above, the detailed description thereof will be omitted. Explaining the difference or characteristic, a stopping position of the whole-surface belt 17, i.e., a stopping position of the trailing end of the second original S′ is altered or changed in comparison with the stopping position thereof in the normal mode. In the normal mode, the whole-surface belt 17 is stopped when the clock is advance by a predetermined count after the original S′ has passed through the sensor 20′, so that the original is stopped at a position R₁ shown in Fig. 9A (position from which the reading by means of the reading optical system 27 is initiated). To the contrary, in a one scan mode, when a distance between the first original S′ and the second original S′ is ℓ₂. the stopping position is so controlled that the trailing end of the second original S′ is stopped at a position R₂ shifted toward an upstream side from the position R₁ (in the normal mode) by a distance ℓ₂/2 (refer to Fig. 9A). Consequently, the leading end of the first original S′ protrudes from the image reading area by a distance ℓ₂/2. Accordingly, when the reading of the original images by means of the reading optical system 27 is initiated from the position R₁, as shown in Fig. 12, the lacked widths of the first and second originals S′ will be ℓ₂/2, respectively. When the stopping position of the originals is controlled in this way, as shown in Fig. 12, although the lacked widths of the first and second originals become ℓ₂/2, respectively, since such lack or disappearance occurs only at edge areas of the originals where the density of image information is low or zero, the danger of disappearance of the necessary image information will be more reduced than the conventional case where the width ℓ₂ of the first original is lacked. Then, the originals S′ is read (Fig. 9B), and, after the reading, the whole-surface belt 17 and the sheet discharge rollers 24 are rotated normally to eject the originals S′ on the platen 11 onto the discharge tray 25 (Fig. 9C). Next, a control means of the image forming system for performing the feeding control as mentioned above will be explained. As shown in Fig. 10, the control means or controlling portion 30 comprises a one-chip microcomputer including a ROM and a RAM. The controlling contents shown in Fig. 11 are stored in the ROM, and the original feeding apparatus 12 is controlled in accordance with the controlling contents. To one input terminal of the controlling portion 30, the sensors 20′, 26 and photo-interrupter 23 are connected, and the controlling portion receives signals from these sensors 20′, 26 and photo-interrupter 23 to calculate the size and the number of the originals S′ on the platen 11 and the shifting amount of the whole-surface belt 17. Further, a mode switch 31 for setting the copy mode and a copy sheet size switch 32 for setting the size of a copy sheet as a recording medium (which switches are arranged in an operation panel (not shown) of the copying machine 10) are connected to the other input terminal of the controlling portion 30. When the one scan mode (wherein the images of a plurality of originals S′ are printed on one surface of the single copy sheet) is set by the mode switch 31 and the size of the copy sheet is set by the copy sheet size switch 32, the controlling portion 30 calculates the shifting amount of the stopping position of the originals in the one scan mode. More particularly, the controlling portion 30 calculates the shifting amount of the originals by performing the following calculation on the basis of the aforementioned input signals: [(Σℓ ₁ + Σℓ ₂) - ℓ₃] ÷ 2. where, Σℓ₁ is the total length of the originals, Σℓ₂ is the total clearance between the originals, and ℓ₃ is a length of the recording sheet (copy sheet). The driving motor 21 of the original feeding apparatus 12 is connected to an output terminal of the controlling portion 30, which motor 21 is controlled on the basis of the calculated shifting amount. For example, when two originals each having the A4 size (length of 210 mm) are simultaneously rested on the platen, if the distance between two originals is 5 mm (determined by the distance of the nip between the feed rollers 16), a value of Σℓ₁ + Σℓ₂ (i.e., total original length plus total clearance between the originals) becomes 210 x 2 + 5 = 425 mm. In this case, if the size of the copy sheet is designated to A3 (length of 420 mm) and the magnification is designated to 100 %, the shifting amount becomes: [425 - (420/1.00)] ÷ 2 = 2.5 mm. Accordingly, when the printing is effected in this mode, the copy including the lacked areas of 2.5 mm regarding the first and second originals S′ will be obtained. On the other hand, when the copy sheet is designated to A4 (longitudinal) and the magnification is designated to 50 %, the shifting amount becomes: [425 - (210/0.50) ] ÷ 2 = 2.5 mm. Thus, the original stopping position is shifted by 2.5 mm as the same as the above case. Next, the original feeding sequence performed by the controlling portion 30 will be explained with reference to a flow chart shown in Fig. 11. First of all, in a step S1, the originals each having the size A4 are stacked on the stacking tray 13 with the imaged surfaces thereof turned upside to form the original stack S. Then, in a step S2, for example, the one scan mode is set by the mode switch 31 and the A3 size is set by the copy sheet size switch 32. Next, in a step S3, it is judged whether the copy start signal exists or not, and if the copy start is requested (i.e., if YES), the sequence goes to a step S4, where it is judged whether the one scan mode or the normal mode is required. If the normal mode is required, the sequence goes to a step S5, where the printing is initiated in the normal copy sequence. On the other hand, if the one scan mode is required, the sequence goes to a step S6, where a first original S′ is supplied, and in a step S7 it is judged whether the supplying of the first original S′ has been finished or not. If finished (YES), in a step S8 a second original S′ is supplied. In this case, the second original is fed in such a manner that the trailing end of the second original S′ is positioned at the stopping position R₂ shifted toward the upstream side by the distance ℓ₂/2 in comparison with the stopping position R₂ in the normal mode. Then, in a step S9, it is judged whether the supplying of the second original S′ has been finished or not. If finished (YES), in a step S10 the originals S′ are read. In this way, the images of two originals S′ are printed on a single surface of the copy sheet having the size A4 with the same lacked areas of the images of the first and second originals S′ (see Fig. 12). After the reading, in a step S11, the originals S′ are discharged onto the sheet discharge tray 25, and in a step S11 it is judged whether any originals S′ remain on the stacking tray 13. If remains (YES), the sequence returns to the step S6, and the same cycles are repeated until the there is no original on the stacking tray. In the illustrated embodiment (Fig. 9), while the original stopping position R₂ was shifted toward the upstream side by the distance ℓ₂/2 from the reading position to equalize the lacked widths of the first and second originals S′ (to prevent the localization of the lacked area only in the first original S′), alternatively, the reading start position of the reading optical system 27 may be shifted toward a downstream side by a distance ℓ₂/2 as shown in Fig. 9A while keeping the original stopping position as same as that in the normal mode. That is to say, the whole-surface belt 17 is stopped when the trailing end of the second original S′ reaches at a predetermined position. This predetermined position corresponds to the original stopping position R₁ in the normal mode. Then, the reading of the originals is effected by the scanning of the reading optical system 27. However, in this case, an optical scanning motor 27d (Fig. 10) is controlled by the controlling portion 30 to alter or change the reading start position to a position R₃ shifted toward the downstream side by the distance ℓ₂/2 from the reading start position R₁ in the normal mode or a book mode. In this way, as similar to the previous embodiment, the lacked width of the first original S′ will be equalized to that of the second original S′. Further, while the original stopping position R₂ was shifted toward the upstream side by the distance ℓ₂/2 from the reading position R₁ in the previous embodiment (Fig. 9) and while the reading start position was shifted toward the downstream side by the distance ℓ₂/2 from the reading position R₁ in the normal mode to equalize the lacked widths of the first and second originals S′, alternatively, the timing of energization of a regist clutch 33 of the recording sheet feeding mechanism may be delayed by ℓ₂/2 by means of the controlling portion 30. That is to say, as shown in Fig. 13, the timing between the movements of an image information 34a₁ of the first original and of an image information 34a₂ of the second original given on the photosensitive drum 34 and the transferring of these images onto a recording sheet 35 may be delayed (initiation of the supplying the recording sheet is delayed) by a time corresponding to the distance ℓ₂/2 by controlling the regist clutch 33 by means of the controlling portion 30, thus equalizing the lacked widths of the first and second originals S′. Incidentally, the shifting amount between the first image information 34a₁ and the second image information 34a₂ and the recording sheet 35 corresponds to the distance ℓ₂/2 when the magnification is 1 (100%); however, if the magnification is not 1 but α, such shifting amount will be (ℓ₂/2) x α. This is required for the reason that, since the image information 34a₁ on the photosensitive drum 34 is an image which has already been magnified, the shifting amount of the recording sheet 35 must also be magnified. Next, an example that the copies with the proper page sequence can be obtained will be explained with reference to Figs. 14 to 19. Figs. 14 to 19 show a further embodiment of the present invention, where Fig. 14 is a schematic sectional view of an sheet feeding apparatus of a copying machine to which the present invention is applied, Figs. 15A to 15G and Figs. 16A to 16D are schematic explanatory views for illustrating the operation of the original feeding apparatus, Fig. 17 is a block diagram of a control means for the copying machine and Fig. 18 is a flow chart showing the controlling contents for the control means. In Fig. 14, the copying machine 410 has a platen 411 above which an sheet feeding apparatus 420 is disposed. As shown in Fig. 14, the original feeding apparatus 420 comprises a stacking tray 421 on which an original stack S is received, a separating portion 422 (conveying roller 422a and separating belt 422b) for separating an original from the original stack S on the stacking tray 421, a substantially U-shaped guide 423 for guiding the separated original to the platen 411, feed rollers 423a arranged at an appropriate position along the guide 423 and adapted to feed the original toward the platen 411, and a whole-surface belt 424 for setting the original at a predetermined position on the platen 411. At a downstream side of the stacking tray 42, there are arranged a semi-circular sheet feed or supply roller 421a and a sensor 421b for detecting a leading end of the original. Further, the conveying roller 422a of the separating portion 422 is rotated in an anti-clockwise direction (Fig. 14) and the separating belt 422b is disposed adjacent to the conveying roller 422a and is also rotated in an anti-clockwise direction to separate the original one by one from the bottom of the original stack S on the tray 421. Further, a sensor 423b for detecting the passage of the original is disposed at an appropriate position along the guide 423. Further, the whole-surface belt 424 is constituted by a driving roller 424a disposed at one end (left end in Fig. 14) of the platen 411, a driven roller 424b disposed at the other end (right end in Fig. 14) of the platen 411, and a conveying belt 424c extending between and engaged by these rollers 424a, 424b. One end of a driving shaft 425a of a driving motor 425 is connected to a driving shaft 424a′ of the driving roller 424a so that the conveying belt 424c can be rotated in directions shown by arrows a and b in Fig. 14 by means of the driving motor 425. Incidentally, a clock plate 425b is connected to the other end of the driving shaft 425a and a photo-interrupter 426 is disposed near the clock plate 425b. The photo-interrupter 426 controls a moving amount of the conveying belt 424c by counting the number of slits formed in the clock plate 425b. Further, at the other end of the platen 411, there are arranged a substantially U-shaped guide 427 and an ejector roller or sheet discharge roller 427a (near an outlet of the guide 427), so that the original on the platen 411 can be ejected or discharged onto a sheet discharge tray 428 disposed above the conveying belt 424c. A sensor 427b for detecting the original is disposed at an appropriate position along the guide 427. The copying machine 410 includes an optical reading system 412 acting as a reading means for reading the image of the original rested on the platen 411. The optical reading system 412 is constituted by an exposure lamp 412a, a scanning mirror 412b and a lens 412c and is so designed that the image of the original is scanned by moving the optical system by means of an optical scanning motor (not shown) while illuminating the original by the exposure lamp 412a, thereby directing the reflected light from the original to the photosensitive drum through the scanning mirror 412b and the lens 412c. Next, an operation of the above-mentioned copying machine will be explained with reference to Figs. 14, 15A to 15G and 16A to 16D. First of all, an example that the image information is printed on a single surface of the recording sheet will be described with reference to Figs. 14 and 15A to 15G. As shown in Fig. 15A, the original stack S is set on the stacking tray 421 with imaged surfaces thereof turned upside. Now, it is assumed that five originals S₁, S₂, S₃ S₄ and S₅ each having a size of A4 and an image recorded on only one surface thereof are stacked onto the stacking tray 421. Then, when the one scan copy mode is selected by the mode selection switch (not shown) and the copy start switch (not shown) is depressed, the sheet feeding apparatus 420 is activated to create a count mode for counting the number of the originals. In this count mode, the supply roller 421a and the separating portion 422 are driven to separate a lowermost or fifth original S₅ from the original stack on the stacking tray 421 and feed it to the feed rollers 423a until a leading end of the fifth original S₅ abuts against the feed rollers 423a to form a loop in the original. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a (Fig. 14) to feed the original S₅ toward the platen 411. When a predetermined clock is advanced after the trailing end of the original S₅ has passed through the sensor 423b (i.e., the trailing end of the original S₅ reaches near a reading start position P shown in Fig. 14) , the original is temporarily stopped. Then, the supply roller 421a and the separating portion 422 are driven to separate and feed a next or fourth original S₄ until a leading end of this original abuts against the feed rollers 423a to form a predetermined loop in this original. Thereafter, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a (Fig. 14) to further move the fifth original S₅ from near the reading start position P to the right by a distance corresponding to the size of the original (the length of the A4 size original) and to feed the fourth original S₄ near the reading start position P, thereby resting two originals S₅, S₄ adjacent to each other on the platen 411 (refer to Fig. 15B). Then, a third original S₃ is separated and fed until a leading end of the original abuts against the feed rollers 423a to form a predetermined loop in this original. Thereafter, the feed rollers 423a, whole-surface belt 424 and ejector rollers 427a are rotated in the direction shown by the arrow a (Fig. 14) to eject the fifth original S₅ onto the sheet discharge tray 428, to move the fourth original S₄ to a position where the fifth original S₅ was positioned, and to move the third original S₃ near the reading start position P; and then, these elements 423a - 427a are stopped. The above-mentioned cycles are repeated until there is no original on the stacking tray 421 (refer to Fig. 15C). Incidentally, in counting the number of the originals, the originals may be continuously fed without stopping the originals. By counting the above cycles, the number N₁ of the originals can be counted, and the counted value N₁ is stored in a RAM 33 (Fig. 17) of the controlling portion 30. Further, during such counting operation, the size of the original is detected, and the detected size information is also stored in the RAM 33. After the above-mentioned count mode is finished, as shown in Fig. 15D, the originals on the discharge tray 428 are again set on the stacking tray 421 as the same atitude as the previous one, and then the copy start switch (not shown) is depressed again. Now, it is assumed that each original has A4 size, the recording sheet has A3 size, the magnification is 100 % and the number N₂ of the originals to be simultaneously fed to the platen 411 is two. Further, since the number N₁ of the originals is five and the single-sided printing is effected, the controlling portion 30 seeks the residual N₃ by dividing N₁ by N₂ (i.e., N₃ = 1; 5 ÷ 2 = 2 x 2 + 1). When N₃ = 1 is calculated, the copying operation is effected in a mode wherein at first only the original corresponding to the last page is fed to the platen so that the image thereon is printed on a single recording sheet 414 and thereafter two originals are simultaneously fed to the platen 411 so that the images of these two originals are printed on a single same recording sheet. That is to say, in response to the re-start signal, the supply roller 421a and the separating portion 422 are rotated to separate the lowermost or fifth original S₅ abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a in Fig. 14 to feed the original S₅ toward the platen 411. After the trailing end of the original S₅ has passed through the sensor 423b, the original S₅ is moved until the trailing end of the original S₅ reaches a position spaced apart from the reading start position P on the platen 411 by a distance corresponding to the length of the original (length of A4 size). In this condition (Fig. 15E), the optical reading system 412 reads the image information of the original S₅ to form the image information on the photosensitive drum. The image formed on the photosensitive drum is transferred onto the recording sheet 414 and then the transferred image is fixed to the sheet. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427a are rotated in the direction shown by the arrow a in Fig. 14 to discharge the original S₅ from the platen 411 to the sheet discharge tray 428. Then, the supply roller 421a and the separating portion 422 are rotated again to separate the fourth original S₄ (now a lowermost original) and to feed it until the leading end of the original S₄ abuts against the feed rollers 423a to form a predetermined loop in the original. Thereafter, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a in Fig. 14 to feed the original S₄ toward the platen 411. The original S₄ is once stopped when the trailing end of this original has passed through the feed rollers 423a. Then, the whole-surface belt 424 is rotated reversely in the direction shown by the arrow b in Fig. 14 until the trailing end of the original S₄ abuts against the feed rollers 423a. Thereafter, the third original S₃ is separated from the original stack and is fed until the trailing end of this original abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are again rotated in the direction a in Fig. 14 until the trailing end of the original S₃ has passed through the sensor 423b and reaches the reading start position P on the platen 411. In this way, two originals S₄ and S₃ are rested on the platen 411 with a minute or fine clearance therebetween. In this condition, as shown in Fig. 15F, the optical reading system 412 reads the image information on each original S₄, S₃ to form the images on the photosensitive drum. The images formed on the photosensitive drum 413 are then transferred onto a recording sheet 412 and are fixed thereon. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427a are rotated in the direction shown by the arrow a in Fig. 14 to discharge the originals S₄, S₃ from the platen 411 onto the sheet discharge tray 428. In the same manner as mentioned above, as shown in Fig. 15G, the originals S₁ and S₂ are rested on the platen 411 with a minute clearance therebetween, and the image information of each original S₁, S₂ is read by the optical reading system 412, thereby printing the images on the recording sheet 414. In this way, the image information of each original S₁, S₂, S₃, S₄, S₅ is sequentially printed on the recording sheets 414 from the first page, thus preventing a so-called white blank to obtain good one-sided copies. Next, an example that images are printed on both surfaces of a recording sheet A will be explained with reference to Figs. 14 and 16A to 16D. An original stack S is set on the stacking tray 421 with imaged surfaces thereof turned upside. Now, it is assumed that five originals S₁, S₂, S₃, S₄, and S₅ each having a size of A4 and an image recorded on only one surface thereof are stacked onto the stacking tray 421. Then, when the one scan copy mode is selected by the mode selection switch (not shown) and the copy start switch (not shown) is depressed, the original feeding apparatus 420 is activated to create a count mode for counting the number of the originals. This count mode is effected in the same manner as in the case where the image information is printed on one surface of the recording sheet (Figs. 15A to 15G). In this count mode, the number N₁ of the originals is counted by counting the number of the original feeding cycles and the counted value N₁ is stored in the RAM 33 (Fig. 17) of the controlling portion 30. Further, during such counting operation, the size of the original is detected, and the detected size information is also stored in the RAM 33. After the above-mentioned count mode is finished, as shown in Fig. 16A, the originals on the discharge tray 428 are again set on the stacking tray 421 as the same attitude as the previous one, and then the copy start switch (not shown) is depressed. Now, it is assumed that each original has A4 size, the recording sheet has A3 size, the magnification is 100% and the number N₂ of the originals to be simultaneously fed to the platen 411 is two. Further, since the number N₁ of the originals is five and the both-sided printing is effected, the controlling portion 30 seeks the residual N₄ by dividing N₁ by (N₂ x 2) (i.e., N₄ = 1; 5 ÷ (2 x 2) = (2 x 2) x 1 + 1). When the residual N₄ = 1 is calculated, the copying operation in effected in a copying mode wherein at first only the original corresponding to the last page is fed to the platen so that the image thereon is printed on a single recording sheet 414 and thereafter four images of four originals (N₂ x 2 = 4) are printed on a single same recording sheet. That is to say, in response to the re-start signal, the supply roller 421a and the separating portion 422 are rotated to separate the lowermost or fifth original S₅ from the original stack S and to feed it until the leading end of the original S₅ abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a in Fig. 14 to feed the original S₅ toward the platen 411. After the trailing end of the original S₅ has passed through the sensor 423b, the original S₅ is moved until the trailing end of the original S₅ reaches a position spaced apart from the reading start position P on the platen 411 by a distance corresponding to the length of the original (length of A4 size). In this condition (Fig. 16B), the optical reading system 412 reads the image information of the original S₅ to form the image information on the photosensitive drum. The image formed on the photosensitive drum is transferred onto the recording sheet 414 of A3 size and then the transferred image is fixed to the sheet. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427a are rotated in the direction shown by the arrow a in Fig. 14 to discharge the original S₅ from the platen 411 to the sheet discharge tray 428. Then, the supply roller 421a and the separating portion 422 are rotated again to separate the fourth original S₄ (now a lowermost original) and to feed it until the leading end of the original S₄ abuts against the feed rollers 423a to form a predetermined loop in the original. Thereafter, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow a in Fig. 14 to feed the original S₄ toward the platen 411. The original S₄ is once stopped when the trailing end of this original has passed through the feed rollers 423a. Then, the whole-surface belt 424 is rotated reversely in the direction shown by the arrow b in Fig. 14 until the trailing end of the original S₄ abuts against the feed rollers 423a. Thereafter, the third original S₃ is separated from the original stack and is fed until the trailing end of this original abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are again rotated in the direction a in Fig. 14 until the trailing end of the original S₃ has passed through the sensor 423b and reaches the reading start position P on the platen 411. In this way, two originals S₄ and S₃ are rested on the platen 411 with a minute or fine clearance therebetween. In this condition, as shown in Fig. 16C, the optical reading system 412 reads the image information of each original S₄, S₃ to form the images on the photosensitive drum. The images formed on the photosensitive drum are then transferred onto one surface of a recording sheet 414 of A3 size and are fixed thereon. And, this recording sheet 414 is once stocked on the intermediate tray. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427a are rotated in the direction shown by the arrow a in Fig. 14 to discharge the originals S₄, S₃ from the platen 411 onto the sheet discharge tray 428. In the same manner as mentioned above, the first and second originals S₁ and S₂ are rested on the platen 411 with a minute clearance therebetween. And, as shown in Fig. 16D, the image information of each original S₁, S₂ is read by the optical reading system 412, thereby printing the images on the other surface of the recording sheet 414 stocked on the intermediate tray. Thereafter, the recording sheet is ejected. In this way, the image information of each original S₁, S₂, S₃, S₄, S₅ is sequentially printed on the recording sheets 414 from the first page, thus preventing the so-called white blank to obtain good both-sided copies. Next, the controlling portion 30 acting as the control means for controlling the original feeding apparatus 20 as mentioned above will be explained with reference to Fig. 17. The controlling portion 30 comprises a CPU 431 for controlling the whole sheet feeding apparatus 20, a ROM 432 for storing the controlling contents shown in Fig. 18 and other various data, a RAM 433 used as a work area for the CPU 431 and adapted to temporarily store various data such as the number of the originals, and an interface 434. The above-mentioned sensors 421b, 423b, 427b and the photo-interrupter 426 are connected to the CPU through the interface so that signals emitted from these elements 421b - 426 are inputted to the CPU 431. Further, control signals from the CPU 431 can be supplied to the supply roller or sheet feed roller 421a, separating portion 422, feed rollers or conveying rollers 423a, driving motor 425 and sheet discharging rollers 427a through the interface. When the copy start switch is depressed, the controlling portion 30 starts to perform the controlling operation in accordance with the controlling contents of the flow chart shown in Fig. 18. That is to say, in a step S10, it is judged whether the one scan mode or the normal copy mode is requested; if the normal copy mode is requested, the sequence goes to a step S11, where the printing is initiated in the normal copy sequence. On the other hand, if the one scan copy mode is requested, the sequence goes to a step S12, where the count mode is executed. In this count mode, the number N₁ of the originals is counted and at the same time the size of the original is detected. Then, the sequence goes to a step S13, where the number N₂ of the originals to be simultaneously set on the platen 411 is calculated on the basis of the size of the original, the size of the recording sheet, the magnification and the like. Then, in a step S14, it is judged whether the one-surface copy or the both-surface copy is requested; if one-surface copy (YES), the sequence goes to a step S15, where the residual N₃ is calculated by dividing the number N₁ of the originals by the number N₂ of the originals to be simultaneously set. Then, in a step S16, N₃ (in number) originals from the last page are set on the platen 411, and the images of these originals are printed on a same single recording sheet 414. Then, in a step S17, the originals are treated by N₂ sheets and the images thereof are printed out on a same recording sheet 414. That is to say, N₂ (in number) originals are simultaneously set on the platen 411 and the images of these originals are printed on a same recording sheet 414. Then, in a step S18, the treatments in the step S17 are repeated until the originals on the stacking tray 421 are exhausted. When there is no original on the stacking tray 421, the treatment is finished. On the other hand, if it is judged that the both-surface copy is requested in the step S14, the sequence goes to a step S19, where the residual or rest N₄ is calculated by dividing the number N₁ of the originals by a value (N₂ x 2). Then, in a step S20, N₄ (in number) originals from the last page are set on the platen 411, and the images of these originals are printed on a same single recording sheet 414. Then, in a step S21, the originals are treated by N₂ sheets and the images thereof are printed out on a same recording sheet 414. That is to say, first N₂ (in number) originals are simultaneously set on the platen 411 and the images of these originals are printed on a same recording sheet 414, and then the remaining N₂ (in number) originals are simultaneously set on the platen 411 and the images of these originals are printed on a same recording sheet 414. Then, in a step S22, the treatments in the step S21 are repeated until the originals on the stacking tray 421 are exhausted. When there is no original on the stacking tray 421, the treatment is finished. In the illustrated embodiment (Figs. 14 - 18), while the original was fed from the last page to the platen 411, alternatively, the original may be fed from the first page to the platen 411. Fig. 19 schematically shows an sheet feeding apparatus 420 for carrying out the above alteration. In the sheet feeding apparatus 420, at a downstream side of the stacking tray 421, there is arranged a semi-circular sheet supply roller 421c for separating an uppermost original from the original stack S on the stacking tray 421. Further, a sheet discharge tray 428a is disposed to extend rightwardly and upwardly from the other end of the platen 411, rather than being disposed above the conveying belt 424c. In addition, a sheet discharging rollers 427c are disposed between the other end of the platen 411 and the sheet discharge tray 428a. These points are different from those of the sheet feeding apparatus 420 of Fig. 14, and other construction is the same as that of the apparatus of Fig. 14. Incidentally, the constructural elements shown in Fig. 19 as same as those shown in Fig. 14 are designated by the same reference numerals and the explanation thereof will be omitted. Next, an example that the originals are fed to the platen 411 sequentially from the first page by means of the sheet feeding apparatus 420 and the images of the sheet originals are printed on one surface of the respective recording sheets will be explained with reference to Figs. 20A to 20F. First of all, an original stack S is set on the stacking tray 421 with imaged surfaces thereof turned upside. Now, it is assumed that five originals S₁, S₂, S₃, S₄ and S₅ each having a size of A4 and an image recorded on only one surface thereof are stacked onto the stacking tray 421. Then, when the one scan copy mode is selected by the mode selection switch (not shown) and the copy start switch (not shown) is depressed, the sheet feeding apparatus 420 is activated to create a count mode for counting the number of the originals. In this count mode, the supply roller 421c and the separating portion 422 are driven to separate an uppermost or first original S₁ from the original stack on the stacking tray 421 and feed it to the feed rollers 423a until a leading end of the first original S₁ abuts against the feed rollers 423a to form a loop in the original. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c (Fig. 19) to feed the original S₁ toward the platen 411. When a predetermined clock is advanced after the trailing end of the original S₁ has passed through the sensor 423b (i.e., the trailing end of the original S₁ reaches near a P shown in Fig. 19), the original is temporarily stopped. Then, the supply roller 421c and the separating portion 422 are driven to separate and feed a next or second original S₂ until a leading end of this original abuts against the feed rollers 423a to form a predetermined loop in this original. Thereafter, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c (Fig. 19) to further move the first original S₁ from near the reading start position P to the right by a distance corresponding to the size of the original (the length of the A4 size original) and to feed the second original S₂ near the reading start position P, thereby resting two originals S₁, S₂ adjacent to each other. Then, in the same manner as the above, a third original S₃ is separated and fed until a leading end of the original abuts against the feed rollers 423a to form a predetermined loop in this original. Thereafter, the feed rollers 423a, whole-surface belt 424 and ejector rollers 427c are rotated in the direction shown by the arrow c (Fig. 19) to eject the first original S₁ onto the sheet discharge tray 428a, to move the second original S₂ to a position where the first original S₁ was positioned, and to move the third original S₃ near the reading start position P; and then, these elements 423a - 427c are stopped. The above-mentioned cycles are repeated until all of the originals on the stacking tray 421 are ejected on the sheet discharge tray 428a. By counting the above cycles, the number N₁ of the originals can be counted, and the counted value N₁ is stored in a RAM 33 (Fig. 17) of the controlling portion 430. Further, during such counting operation, the size of the original is detected, and the detected size information is also stored in the RAM 33. After the above-mentioned count mode is finished, as shown in Fig. 20A, the originals on the discharge tray 428a are again set on the stacking tray 421 as the same attitude as the previous one, and then the copy start switch (not shown) is depressed. Now, it is assumed that each original has A4 size, the recording sheet has A3 size, the magnification is 100% and the number N₂ of the originals to be simultaneously to the platen 411 is two. Further, since the number N₁ of the originals is five and the one-surface printing is effected, the controlling portion 30 seeks the rest or residual N₃ by dividing N₁ by N₂ i.e., N₃ = 1; 5 ÷ 2 = 2 x 2 + 1). When the rest N₃ = 1 is calculated, the copying operation is effected in a mode wherein the originals are printed by two sheets (N₂ = 2) on a same recording sheet 414 and thereafter the image of the original S₅ corresponding to the last page is printed on a single recording sheet 414. That is to say, in response to the re-start signal, the supply roller 421c and the separating portion 422 are rotated to separate the uppermost or first original S₁ from the original stack and to feed it until the leading end of the original S₁ abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c in Fig. 19 to feed the original S₁ toward the platen 411. After a trailing end of the original S₁ has passed through the sensor 423b, this original is once stopped. Then, the whole-surface belt 424 is rotated reversely in the direction shown by the arrow d in Fig. 19 to abut the trailing end of the original S₁ against the feed rollers 423a, and then the belt is stopped. Then, the second original S₂ is separated and is fed until the trailing end thereof abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated again in the direction c in Fig. 19 to feed the originals until the trailing end of the second original S₂ has passed through the sensor 423b and reaches the position P, and then the feed rollers and the belt are stopped. In this way, two originals S₁ and S₂ are rested on the platen 411 with a minute clearance therebetween (the clearance between two originals can be further reduced by utilizing the method described in Figs. 4 to 8). In this condition, as shown in Fig. 20B, the optical reading system 412 reads the image information of each original S₁, S₂ to form the images on the photosensitive drum. The images formed on the photosensitive drum are transferred onto the recording sheet 414 and then the transferred images are fixed to the sheet. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427c are rotated in the direction shown by the arrow c in Fig. 19 to discharge the originals S₁, S₂ from the platen 411 to the sheet discharge tray 428a. In the same manner as mentioned above, as shown in Fig. 20C, the third and fourth originals S₃, S₄ are rested on the platen 411 with a minute clearance therebetween, and the optical reading system 412 reads the image information of each originals S₃, S₄ to print the images on a recording sheet 414. Then, the supply roller 421c and the separating portion 422 are rotated to separated the final or fifth original S₅ and to feed it until the trailing end of the original abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c in Fig. 19 until the trailing end of the fifth original S₅ has passed through the sensor 423b and reaches a position spaced apart from the position P on the platen 411 toward a downstream side by a distance corresponding to the length of the original (length of A4 size). In this condition, as shown in Fig. 20D, the optical reading system 412 reads the image information of the original S₅ to form the image information on the photosensitive drum. The image formed on the photosensitive drum is transferred onto the recording sheet 414 and then the transferred image is fixed to the sheet. When the printing is finished, as shown in Fig. 20E, the whole-surface belt 424 and the ejector rollers 427c are rotated to discharge the original S₅ from the platen 411 to the sheet discharge tray 428a. In this way, the images of the originals S₁, S₂, S₃, S₄ and S₅ are sequentially recorded on the recording sheets A from the first page, thus preventing the so-called white blank to obtain good one-surface copies. Next, an example that the originals are fed to the platen 411 sequentially from the first page by means of the sheet feeding apparatus 420 and the images of the originals are printed on both surfaces of the respective recording sheets will be explained with reference to Figs. 21A to 21D. First of all, an original stack S is set on the stacking tray 421 with imaged surfaces thereof turned upside. Now, it is assumed that five originals S₁, S₂, S₃, S₄, and S₅ each having a size of A4 and an image recorded on only one surface thereof are stacked onto the stacking tray 421. Then, when the one scan copy mode is selected by the mode selection switch (not shown) and the copy start switch (not shown) is depressed, the sheet feeding apparatus 420 is activated to create a count mode for counting the number of the originals. This count mode is effected in the same manner as in the case where the image information is printed on one surface of the recording sheet 414 (Figs. 20A to 20E). In this count mode, the number N₁ of the originals is counted by counting the number of the original feeding cycles and the counted value N₁ is stored in the RAM 433 (Fig. 17) of the controlling portion 430. Further, during such counting operation, the size of the original is detected, and the detected size information is also stored in the RAM 433. After the above-mentioned count mode is finished, as shown in Fig. 21A, the originals on the discharge tray 428a are again set on the stacking tray 421 as the same attitude as the previous one, and then the copy start switch (not shown) is depressed. Now, it is assumed that each original has A4 size, the recording sheet has A3 size, the magnification is 100% and the number N₂ of the originals to be simultaneously fed to the platen 411 is two. Further, since the number N₁ of the originals is five and the both-surface printing is effected, the controlling portion 430 seeks the residual N₄ by dividing N₁ by (N₂ x 2) (i.e., N₄ = 1; 5 ÷ (2 x 2) = (2 x 2) x 1 + 1). When the residual N₄ = 1 is calculated, the copying operation is effected in a mode wherein at first four images of four originals (N₂ x 2 = 4) are printed on a single same recording sheet and thereafter the last original corresponding to the last page is fed to the platen so that the image thereon is printed on a single recording sheet 414. That is to say, in response to the re-start signal, the supply roller 421c and the separating portion 422 are rotated to separate the uppermost or first original S₁ from the original stack S and to feed it until the leading end of the original S₁ abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c in Fig. 19 to feed the original S₁ toward the platen 411. After the trailing end of the original S₁ has passed through the sensor 423b and a predetermined clock has been advanced, the original S₁ is once stopped (near the position P in Fig. 19). Then, the whole-surface belt 424 is rotated reversely in the direction shown by the arrow d in Fig. 19 to abut the trailing end of the original S₁, and then the belt is stopped. Then, the second original S₂ is separated and is fed until the trailing end of this original abuts against the feed rollers 423a to form a predetermined loop therein. Thereafter, the feed rollers 423a and the whole-surface belt 424 are rotated again in the direction shown by the arrow c in Fig. 19 until the trailing end of the second original S₂ has passed through the sensor 423b and reaches the position P on the platen 411, and then the rollers 423a and the belt 424 are stopped. In this way, two originals S₁ and S₂ are rested side by side on the platen 411 with a minute clearance therebetween. In this condition, as shown in Fig. 21B, the optical reading system 412 reads the image information of each original S₁, S₂ to form the images on the photosensitive drum. The images formed on the photosensitive drum are then transferred onto one surface of a recording sheet 414 and are fixed thereon. And, this recording sheet 414 is once stocked on the intermediate tray. When the reading is finished, the whole-surface belt 424 and the ejector rollers 427c are rotated in the direction shown by the arrow c in Fig. 19 to discharge the originals S₁, S₂ from the platen 411 onto the sheet discharge tray 428a. In the same manner as mentioned above, as shown in Fig. 21C, the third and fourth originals S₃, S₄ are rested on the platen 411 a minute clearance therebetween. The image information of each original S₃, S₄ is read by the optical reading system 412, thereby printing the images on the other surface of the recording sheet 414 conveyed from the intermediate tray to the photosensitive drum. Thereafter, the recording sheet 414 having one surface on which the images of the originals S₁, S₂ were printed and the other surface on which the images of the originals S₃, S₄ were printed is ejected onto a tray 414d. Then, the supply roller 421c and the separating portion 422 are rotated to separate the last or fifth original S₅ and to feed it until the leading end of this original abuts against the feed rollers 423a to form a predetermined loop therein. Then, the feed rollers 423a and the whole-surface belt 424 are rotated in the direction shown by the arrow c in Fig. 19 until the trailing end of the original S₅ has passed through the sensor 423b and reach a position spaced apart from the position P on the platen 411 toward a downstream side by a distance corresponding to the length of the original (length of A4 size), and then the original S₅ is stopped. In this condition, as shown in Fig. 21D, the optical reading system 412 reads the image information of the original S₅ to form the image information on the photosensitive drum. The image formed on the photosensitive drum is transferred onto the recording sheet 414 and then the transferred image is fixed to the sheet. When the printing is finished, the whole-surface belt 424 and the ejector rollers 427c are rotated to discharge the original S₅ from the platen 411 to the sheet discharge tray 428a. In this way, the images of the originals S₁, S₂, S₃, S₄ and S₅ are sequentially recorded on the recording sheets A from the first page, thus preventing the so-called white blank to obtain good both-surface copies. In the above-mentioned first and second alterations (Figs. 14 to 21), while an example that the number of the originals is counted at the count mode and the original size is detected during the count mode was explained, the present invention is not limited to such example, but such data may be inputted from an operating portion of the copying machine 410. Further, while an example that two originals are simultaneously fed to the platen 411 (N₂ = 2) was explained, three, four or more originals may be simultaneously fed to the platen if the size of the original is smaller and the size of the recording sheet is larger. Further, while an example that the magnification is 100% was explained, variable magnifications may be adopted. In addition, while an example that the separate or discrete stacking tray 421 and sheet discharge trays 428a are provided was epxlained, the present invention is not limited to this example, but a circulating original feeding apparatus (RDF type) wherein the original is separated from the bottom of the original stack on the stacking tray and is returned onto the same original stack from an upper side may be adopted. By using this original feeding apparatus of RDF type, it is not needed that the originals are set again after the count mode. Further, while an example that, in feeding the remaining original to the platen, for example in the case shown in Figs. 15A to 15G, the original S₅ is conveyed up to the position spaced apart from the position P on the platen 411 toward the downstream side by the distance corresponding to the length of the original (A4) was explained, the original may be stopped at the position P. Further, while the present invention was applied to the copying machine, it may be applied to a laser beam printer, image reader or the like.

Claims: A sheet feeding apparatus, having first rotary means (14, 18) for supplying an original sheet (S′); second rotary means (16) having paired opposed roller means (16) for feeding said original sheet (S′) from said first rotary means (14, 18); and first control means (20, 21, 22, 23) for rotating said paired opposed roller means (16), characterized in that said first control means (20, 21, 22, 23) are means for rotating said paired opposed roller means (16) for a predetermined time during a feeding of a first sheet (S′₁), for stopping said first sheet, with a trailing end thereof being retained in a nip of said paired opposed roller means (16), for rotating said first rotary means (14, 18) to feed a second sheet (S′₂) into a wedged cavity defined by the peripheral surfaces of said roller means (16), and for subsequently rotating said paired opposed roller means (16), with a leading end of said second sheet (S′₂) being inserted into said nip to feed said first and second sheets (S′₁, S′₂) simultaneously. A sheet feeding apparatus according to claim 1, characterized in that said trailing end of said first sheet (S′₁) is pinched by the nip between said roller means (16) and the leading end of said second sheet (S′₂) is abutted against said roller means (16). A sheet feeding apparatus according to claim 1, characterized in that said trailing end of said first sheet (S′₁) protrudes slightly from said nip of said roller means (16) toward an upstream side, wherein said leading end of said second sheet (S′₂) is abutted against said trailing end of said first sheet (S′₁). A sheet feeding apparatus according to claim 1, characterized in that said second rotary means (16) is a means for resting a plurality of sheets (S′) one behind the other on a predetermined reading position. An image forming apparatus having a sheet feeding apparatus according to one of claims 1 to 3, wherein said paired opposed roller means (16) are means for directing said sheets (S′) fed by said first rotary means (14, 18) onto a platen (11; 411); a sheet stacking tray (301; 400, 402, 408) on which sheets are stacked; supply means (302; 401, 403, 409) for supplying sheets from said stacking tray one by one; an image forming means (34; 413) for reading an original (S′) directed onto said platen (11; 411) and for forming an image of said sheets (S′) on a single sheet (35) fed by said supply means; and a second control means (27; 412) for controlling said image forming means to read a plurality of sheets (S′) fed to and rested one behind the other on said platen (11; 411) and to form images of said plurality of sheets on said single sheet (35). An image forming apparatus according to claim 5, characterized in that said image forming apparatus further comprises an image forming means controlling means (20, 30; 423b, 430) for equalizing an area, where the image is lacked of a most downstream sheet (S₅) and of a most upstream sheet (S₁) in a reading image information of each sheet. An image forming apparatus according to claim 6, characterized in that said image forming means controlling means (20, 30; 423b, 430) is a control means for said second rotary means (16) for controlling a sheet stopping position with respect to said platen (11; 411). An image forming apparatus according to claim 6, characterized in that said image forming means controlling means (20, 30; 423b, 430) is a control means for an image information reading means for controlling a timing of an initiation of said image information reading means with respect to said platen. An image forming apparatus according to claim 6, characterized in that said image forming means controlling means (20, 30; 423b, 430) is a control means for a conveying means for controlling a timing of an initiation of a feeding of said sheet (35).

Inventors: KITAHARA MAKOTO C O CANON KABU, KITAHARA, MAKOTO, C/O CANON KABUSHIKI KAISHA
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1990
Main classification: G03G15
IPC codes: G03B27, G03G15