GB2062547A - Dual mode copying machine - Google Patents

Abstract

A dual mode copying machine has an original supporting plate 1 on which a thick original OB such as a book may be placed, copy medium supporting means which can accommodate copy mediums of different sizes to copy original images of various sizes, and sheet original conveying means 51 provided adjacent to the original supporting plate, so that the conveyance and exposure of sheet-like originals Os larger that the original supporting plate 1 is possible. The sheet original conveying means 51 and the copy medium supporting means are provided on the same side of the machine. <IMAGE>

Description

SPECIFICATION Dual mode copying machine Background of the Invention Field of the Invention This invention relates to a convenient dual mode copying machine which can fully function both as a sheet original copying machine and a thick original copying machine and can increase its copying speed in accordance with copy size and which incorporates various contrivances for providing conveniences of use.

Description of the PriorArt Heretofore, copying machines could be divided into two general groups, namely, the copying machines used exclusively for copying sheet originals and the copying machines capable of copying three-dimensional originals such as books or the like.

The copying machines used exclusively for copying sheet originals are not capable of copying thick originals such as books or the like, but can copy sheet originals simply by feeding the sheet originals into the insertion port and have no backward stroke or the original carriage or the optical system for the same process and thus, can increase the copying speed correspondingly (to about twice).

Further, such copying machines are simple in mechanical construction and accordingly inexpensive. Also, along with the increasing copying speed of the copying machines, original auto feeders are desired from the viewpoint that manually supplying sheet originals cannot catch up with the speed of the machine and is inefficient, and the copying machines used exclusively for copying sheet originals permit such auto feeders to be readily incorporated therein.

The copying machines capable of copying thick originals such as books or the like has a great characteristic that they can copy both sheet originals and books or the like, but because of their construction designed such that an original to be copied must be laid spread out on the original carriage, a sheet original cannot be copied without taking the steps of opening the original cover, placing the sheet original on the original carriage glass, closing the original cover and depressing the copy button as is required when a thick original is to be copied.

Further, the presence of the backward stroke of the original carriage or the optical system means a corresponding loss of time and the copying speed is necessarily decreased for the same process.

Moreover, such copying machines are complicated in mechanical construction and accordingly expensive. Also, it is very difficult to provide such copying machines with auto feeders.

For the reasons set forth above, the abovedescribed two types of copying machines find their own unique markets.

Heretofore, there have been desired the socalled dual mode copying machines which have the functions of both of said two types of machines and some examples thereof have been proposed, but of any of them has the following disadvantages: 1. The sheet original feeding portion is disposed projectedly outwardly of the machine body.

2. The machine body is bulky.

As regards the disadvantage mentioned under item 1 above, the configuration of the machine body is particularly complicated and not only lacks the space for placing originals and copy paper thereon but also lacks even the space for placing thereon small articles (Hotchkiss, pencils, etc.) used for ordinary office work, and the user is forced to carry out the copying work while holding those articles in hand, which means the difficulty with which the copying operation itself is carried out. Also, if the auto feeder portion when not used always remains projected outwardly of the machine body, the user may touch such portion by mistake and the possibility of the user touching such portion would lead to enhanced possibility of fault of the sheet original feeding portion.Clips or the like may drop onto the sheet original feeding portion and in such case, they would be difficult to remove or the operation of the copying machine may be started without the user noticing the dropping of the clips or the like, thus causing an accident.

To eliminate such disadvantages, there is required a contrivance such as enabling part or whole of the auto feeder portion projected outwardly of the machine body to be detached from or accommodated within the machine body during non-use of such feeder portion, or providing a cover for covering the auto feeder portion.

However, designing the auto feeder portion such that part or whole thereof can be detached from or accommodated within the machine body during non-use thereof is cumbersome and manually handling the auto feeder portion having a great weight is a burden to the user. Moreover, a space is required for storing the detached part or whole of the auto feeder portion and there is the danger of the detached auto feeder portion being lost or broken.

Also, the operation of changing over the copy mode between the copying by the sheet original (automatic) feeding using the auto feeder portion and the thick original copying not using the auto feeder portion has been an extra operation to the user.

The disadvantage mentioned under item 2 above will be described by taking a specific example thereof.

For example, consider a copying machine having an original supporting table capable of copying originals of maximum B4 size and having no sheet original feeding function. Generally, the direction in which an original is placed on the original supporting table is such that the shorter side of B4 size original is coincident with the scanning direction A of the optical system. This is for the purpose of reducing the scanning distance of the optical system so much as possible and increasing the copying speed, as well as efficiently effecting the accommodation of transfer paper and reducing the size of the machine body.

Generally, where a B4 size original is to be copied in said direction (hereinafter referred to as the lateral feeding), the machine body becomes somewhat large in the direction perpendicular to the direction of paper feeding but becomes greatly small in the direction parallel to the direction of paper feeding. This is because, as shown in Figure 1 of the accompanying drawings, the areas of transfer papers of respective sizes are combined most efficiently.

Figure 2 of the accompanying drawings shows an example of the copying machine previously described.

A copying machine having the sheet original feeding function can feed and expose long sheetlike originals to light independently of the size of the original supporting table. Accordingly, if transfer paper of a larger size can be fed, a copy of a larger size (for example, A3) will become possible in the same copying machine.

Figure 3 of the accompanying drawings shows a copying machine in which a sheet original feeding portion and a large size transfer paper containing portion are added to the copying machine of Figure 2. The sheet original feeding portion is disposed in the rightward and upper portion of the machine body and projects from the machine body to complicate the configuration of the machine body. Also, only for the reason that a large space is required to contain large size transfer paper, the transfer paper containing portion in the leftward and lower portion of the machine body greatly projects in the shown direction of the machine body.Where supply of transfer paper is effected from a cassette removable with respect to the machine body, a greater space would be required when it is taken into consideration that the cassette is generally mounted or dismounted in a direction parallel to the transfer paper feeding direction and that a space for the mounting and dismounting operation must be taken into account. Also, the fact that the sheet original feeding portion lies in the rightward and upper portion of the machine body and the transfer paper containing portion lies in the leftward and lower portion of the machine body means that portions which can be touched by the user exist over the entire machine body, and this reduces the operability of the machine.Further, when the operation of the sheet original feeding portion is taken into consideration, a space will also be required on the right side of the machine body when the machine is installed.

A copying machine having a bulky machine body including an operational space (for mounting and dismounting of a cassette, use of the sheet original feeding mechanism, etc.) requires a great space for installation and often forms an obstruction when it is not used. Further, the place of installation itself is limited and such machine is very disadvantageous for packing and transportation.

On the other hand, for the fixing device of a copying machine, a method of heating and melting a toner image adhering to the surface of a toner image bearing medium and permanently fixing the toner image on the toner image bearing medium has heretofore been usually adopted.

However, such a heating-fixing method requires a great deal of electric power for the heat source and about 70 to 80% of the total electric power consumed by an entire copying machine is consumed by this fixing device. Also, much time is required for the fixing device to reach a temperature necessary to fix the toner image and copying cannot be started immediately after the main switch of the copying machine has been closed and in addition, the entire copying machine is heated by the heat emitted from the fixing device, whereby the characteristic of the photosensitive medium or the developer may be varied to vary the image and the performance or life thereof may be reduced. Moreover, there is a problem that when the toner image bearing medium jams at the fixing device, it may catch fire.

In a copying machine having the abovedescribed auto feeder, when copying is effected by using the auto feeder, sheets of transfer paper are continuously fed while keeping a close interval therebetween and therefore, there is a continuous loss of heat and a great deal of electric power is required to accomplish sufficient fixation.

Accordingly, the heat emitted from the fixing device is great in quantity and the above-noted disadvantage provides a serious problem.

Thus, the adiabatic or similar countermeasure also becomes complicated, which in turn leads to bulkiness and increased cost of the copying machine.

Also, the electric power consumed by the copying machine must be set by taking into consideration the number of copies per unit of time when the auto feeder is used, but during the copying not using the auto feeder, the number of copies per unit of time is decreased and the preparation of that quantity of electric power is unnecessary and wasteful.

It is an object of the present invention at least partly to alleviate the above-noted disadvantages.

In one aspect the present invention provides a copying machine in which the change-over between the two modes of a dual mode copying machine is effected in association with the sheet original conveying portion.

In another aspect the present invention provides a copying machine which can increase the number of copies per unit of time without increasing the quantity of electric power (W) of the copying machine and which can accomplish complete fixation for any number of copies and can cause the function of the sheet original feeding device to be sufficiently performed.

In a further aspect the present invention provides a dual mode copying machine having an original supporting plate on which a threedimensional original may be placed, copy medium supporting means which can be enlarged to copy mediums of different sizes to copy the images of originals of various sizes, and sheet original conveying means provided by enlarging that side of the machine body which is adjacent to said copy medium supporting means so that sheet-like originals larger than said original supporting plate can be conveyed and exposed to light, and wherein the enlarged portion of said copy medium supporting means enlarged to a size of copy medium which can be conveyed and exposed to light by said sheet original conveying means is substantially coincident with the enlargement of said sheet original conveying means.

The invention will become more fully apparent from the following detailed description thereof taken in conjunction with the accompanying drawings.

Brief Description of the Drawings Figures 1 to 3 are views for illustrating the prior art.

Figure 4 is a cross-sectional view of an example or the copying machine to which the present invention is applicable.

Figure 5 is a cross-sectional view showing the copying machine of the present invention.

Figure 6 is a cross-sectional view showing the auto feeder portion.

Figure 7 is a cross-sectional view showing the fixing station.

Description of the Preferred Embodiments An example of the copying machine to which the present invention is applicable will hereinafter be described with reference to Figure 4.

This copying machine is an electrophotographic copying machine of the powder development and transfer type. Reference numeral 1 designates a transparent original supporting table. An original OB to be copied is placed on the original supporting table 1 with one end of the original registered to the reference position 1, , of the original supporting table, and is held down by an original cover 2. Below the original supporting table 1, there are disposed an original illuminating lamp 3, movable mirrors 4, 5, a fixed in-mirror lens 6 and mirror 7, and a photosensitive drum 8 at respective solid-line positions. A fan 50 is also disposed to cool the original supporting table 1 heated by the original illuminating lamp 3.When a copy button, not shown, is depressed, the photosensitive drum 8 starts to rotate in the clockwise direction and is subjected to application of charge and light by charges and lamps which will hereinafter be described while, at the same time, the original illuminating lamp 3 and movable mirrors 4, 5 which are the movable portions of the optical system are moved to postions 31, 4, and 51 indicated by broken lines. When the photosensitive drum 8 completes a predetermined rotation, an exposure start signal is put out and the original illuminating lamp 3 and the first mirror 4 start to move rightwardly from the broken line position 4, at a velocity equal to the peripheral velocity of the photosensitive drum 8 and the second mirror 5 also starts to move rightwardly from the broken line position 5, at one half of said velocity.The image of the original OB illuminated from therebelow by the original illuminating lamp 3 is formed on the photosensitive drum 8 at an exposure station 9 by the optical system comprising the movable mirrors 4, 5, in-mirror.

lens 6 and mirror 7. When the exposure is terminated by a signal corresponding to the size, the original illuminating lamp 3 and movable mirrors 4, 5 stop their rightward movement and immediately return in the opposite direction, namely, leftwardly as viewed in Figure 4, and thus repeat the above-described operation in accordance with the number of copies designated in advance by a button, not shown. When the exposure corresponding to the designated number of copies is terminated, the original illuminating lamp 3 and movable mirrors 4, 5 return to and stop at their solid line positions. The velocity of their leftward movement is higher than the velocity of their rightward movement to enhance the copying efficiency.

The photosensitive drum 8 comprises a transparent insulating layer overlaid on a photosensitive layer and is rotated in the clockwise direction as previously described. The photosensitive drum 8 is subjected to AC discharging by an AC discharger 10 supplied with an AC high voltage current from a high voltage power source, not shown, while at the same time it is subjected to the exposure by a lamp 11, whereby the charges on the surface of the insulating layer and in the photosensitive layer are removed, and then the photosensitive drum is charged to the positive polarity (+) by a primary charger 12 supplied with a positive (+) high voltage current from a high voltage power source, not shown.Subsequently, when the photosensitive drum arrives at the exposure station 9, it is slit-exposed to the image from an illuminating station 13 while, at the same time, it is AC-discharged by an AC discharger 14 supplied with an AC high voltage current from a high voltage power source, not shown. By a whole surface exposure subsequently effected by a lamp 15, an electrostatic latent image is formed on the surface of the photosensitive drum 8, and then the drum 8 enters a developing device 1 6. The developing device 1 6 comprises a container 1 7 for containing developer therein, a developing roller 1 8 and a doctor blade 19, and visuaiizes the electrostatic latent image on the photosensitive drum 8 by developer magnetically attracted to the developing roller 1 8.

Subsequently, transfer paper P fed from a paper supply station is brought into intimate contact with the photosensitive drum 8 and is charged at a transfer charger 20 by a positive (+) high voltage current from a high voltage power source, whereby the image on the photosensitive drum 8 is transferred onto the transfer paper P. After the image transfer has been terminated, the transfer paper P is discharged by a separation discharger 21 supplied with an AC high voltage current from a high voltage power source, whereby the adhesion force of the transfer paper to the photosensitive drum 8 is weakened.

Subsequently, the transfer paper P is attracted by a roller 23 at a station 22 and separated from the photosensitive drum 8, and is directed to a fixing station 26 by a belt 24 and a guide 25. The photosensitive drum 8 has any residual developer thereon removed by the edge 27, of a blade cleaner 27 urged thereagainst, thus becoming ready for another cycle. After having repeated said cycle a number of times corresponding to the number of copies designated in advance by a button, not shown, the photosensitive drum 8 further continues to rotate and has the charge in the photosensitive layer thereof removed by the discharging by the AC discharger 14 and the whole surface exposure by the lamp 15, and rotates by a predetermined amount as the preparation for the next copy cycle, and then stops rotating.

On the other hand, a stock of transfer paper P is contained in a cassette 28 or a paper supply deck 29 which is positioned in the leftward and lower portion of the machine body. Various types of cassette 28 may be prepared in compliance with the various sizes of transfer paper and may be readily interchanged as required. The paper supply deck 29 is also designed to contain various sizes of transfer paper by a simple operation, as required. The stock of transfer paper P contained in the cassette 28 or the paper supply deck 29 is urged against a paper feed roller 30 or 31 with a predetermined pressure, irrespective of the quantity of the paper. When the photosensitive drum 8 arrives at a predetermined position, the paper feed roller 30 or 31 selected in advance by a button, not shown, starts to rotate and feeds the transfer paper P rightwardly as viewed in Figure 4.

The subsequent paper feed is effected by paper feed means such as a pair of rollers 32, 32' or 33, 33'. The transfer paper P is directed to the photosensitive drum 8 by pairs of rollers 36, 36'; 37, 37' and guides 34, 34'; 38, 38' or 35, 35'; 39, 39' and 40, 40'; 41,41 and is synchronized with the image on the photosensitive drum 8, whereafter the transfer paper P is brought into intimate contact with the photosensitive drum 8 and is charged by the transfer charger 20 so that the image is transferred to the transfer paper, as previously described.After the image transfer has been terminated, the transfer paper P is discharged by the separation discharger 21 as previously described, and is separated from the photosensitive drum 8 at the station 22 and transported into a fixing station 26 by a rollerdriven belt 24 and a guide 25. In the fixing station 26, the transfer paper P having an unfixed image on the surface thereof has that image fixed under a predetermined pressure as it passes between rollers 42 and 43 urged against each other with a predetermined pressure and rotated at the same peripheral velocity. After having left the fixing station 26, the transfer paper P has the charge remaining on the surface thereof removed by a discharger 44 and is directed to discharge rollers 47, 48 by guide 45, 46, whereafter the transfer paper is discharged onto a tray 49.

An example of the copying machine in which the auto feeder function is added to the copying machine of Figure 4 will now be described with reference to Figure 5. The copying machine of Figure 5 adopts a fixed original carriage system when it copies thick or three-dimensional originals, and effects copying while moving sheet originals themselves by conveyor rollers when it copies sheet originals.

In Figure 5, reference numerals identical to those in Figure 4 designate the same parts as those of the copying machine of Figure 4 and need not be described.

In Figure 5, an auto feeder portion 51 is provided in the leftward and upper portion of the machine body and has, as the optical system for auto feeder, an original illuminating lamp 52, a fixed mirror 53 and a movable mirror 54. During the copying operation using the original supporting table 1 as described in connection with the example of Figure 4, the movable mirror 54 for auto feeder is disposed at a position which does not interfere with the optical path, namely, a first position indicated by broken line, even when the original illuminating lamp 3 and movable mirrors 4, 5 are moved to their broken line positions 31 4 and 51 to expose the original OB on the original supporting table 1 to light.During the use of the auto feeder, the original illuminating lamp 3 and movable mirrors 4, 5 are stopped at their solid line positions and the movable mirror 54 for auto feeder is moved rightwardly from a first position 541 indicated by broken line and stopped at a second position 54 indicated by solid line. At this time, the optical path for auto feeder is formed by the original illuminating lamp 52 for auto feeder, mirror 53, movable mirror 54, in-mirror lens 6 and fixed mirror 7.When a pile of sheet originals Os is placed on a sheet original insertion bed 55, the uppermost sheet original is separated and moved forward by separation and feed rollers 56, 57 rotated in opposite directions to feed sheet originals and is fed into between guides 58 and 59, and the leading end of the fed sheet original is detected by a detecting element 60 to stop the sheet original temporally. When the photosensitive drum 8 is rotated to a predetermined position, the sheet original Os is again conveyed between a guide glass 63 and a guide plate 64 by rollers 56, 57 and rollers 61,62 in synchronism with the photosensitive drum 8 and is illuminated by the lamp 52, so that the image of the sheet original Os is formed on the photosensitive drum 8 by the mirror 53, movable mirror 54, in-mirror lens 6 and fixed mirror 7.

Subsequently, the sheet original Os is discharged into an original tray 71 by rollers 65, 66, guides 67, 68 and discharge rollers 69, 70. Such operation is effected continuously with sheet originals being as close to one another as possible until the sheet originals Os on the sheet original insertion bed 55 run out.

The sheet original insertion bed 55 and the original tray 71 are supported for counterclockwise rotation by shafts 72 and 73, respectively, and during the use of the auto feeder, they are fixed at their solid line positions by stoppers, not shown, and during non-use of the auto feeder, they are counter-clockwisely rotated so as to be received into their broken line positions and serve as working tables.

A fan 74 is provided to cool the guide glass 63 heated by the original illuminating lamp 52 for auto feeder.

The use of the auto feeder enables a long footage of original to be copied. Accordingly, a large size cassette 28 is sometimes used, but in the present embodiment, the portion for receiving the large size cassette 28' therein is disposed on the same side as that portion of the machine body which has been enlarged by adding the auto feeder, thereby eliminating any useless space in the machine body.

In the copying machines shown in Figures 4 and 5, the size of the original supporting table 1 is made to be as large as B4 size in view of the actual frequency of use, and originals up to B4 size can be copied. The direction in which an original is placed on the original supporting table is such that the shorter side of B4 size original is coincident with the scanning direction of the optical system.

This is for the purpose of shortening the scanning distance of the optical system as much as possible and increasing the copying speed, as well as enabling the transfer paper to be efficiently contained and reducing the size the machine body.

Generally, where a B4 size original is to be copied in said direction (hereinafter referred to as the lateral feed), the machine body is somewhat enlarged in the direction of depth but is greatly reduced in the direction of width. This is because, as shown in Figure 1, the areas of transfer papers of respective sizes become most efficiently overlapped to one another.

In the case of a copying machine having the auto feeder function, a long sheet original can be fed and exposed to light independently of the size of the original supporting table 1. Accordingly, if transfer paper of a large size can be fed, it will become possible to obtain a copy of a larger size in the same copying machine. In the copying machine shown in Figure 5, the size of the original supporting table 1 is B4 as already noted, but by constructing the cassette 28' and the paper supply deck 29 so that transfer paper of A3 size can be fed, a copy of A3 size can be accomplished as far as a sheet original is concerned.Moreover, by disposing the cassette 28' and the paper supply deck 29 so that transfer paper of A3 size is contained on the same side as that portion of the machine body which has been enlarged by adding the auto feeder, the necessity of enlarging the machine body only for containing transfer papers of large sizes is eliminated.

Description will now be made of the original insertion guide and the original discharge tray.

Generally, in the auto feeder portion, there are an original insertion guide and an original discharge tray for auto feeder each having a sufficient area to support originals thereon, and if it is intended to enable originals of the largest possible size to be copied, the original supporting area of the original insertion guide and of the original discharge tray must be made great and in most copying machines, the original insertion guide and the original discharge tray are greatly projected from the machine body. Accordingly, to overcome said disadvantage, it would be greatly effective if at least the original insertion guide and the original discharge tray are detached from the machine body or contained within the machine body during non-use of the auto feeder.

Figure 6 shows the condition during non-use of the auto feeder. The sheet original insertion guide 55 and the original discharge tray 71 have been rotated, as previously described, and stopped with a part 75 of the machine body as the stopper, to form a plane. During the use of the auto feeder, another part 76 of the machine body serves as a stopper, and the guide 55 and tray 71 assume their broken line positions.

A microswitch 77 is provided to effect the changeover between the copying by the automatic sheet original feeding using the auto feeder and the copying using the original supporting table 1.

When the original discharge tray is rotated to its solid line position during non-use of the auto feeder, the microswitch 77 is closed and by this signal, the original supporting table 1 automatically becomes usable. That is, when the copy button is depressed, the original illuminating lamp 3 and movable mirrors 4, 5 start scanning to copy the original placed on the original supporting table 1 and the automatic original feeding mechanism for auto feeder becomes inoperative.

Conversely, when the original discharge tray is brought to its broken line position, the microswitch 77 is opened and by this signal, the copying by the automatic sheet original feeding using the auto feeder portion automatically becomes possible.

That is, even if the copy button is depressed, the original illuminating lamp 3 and movable mirrors 4, 5 are not operated but the optical path for auto feeder by the fixed mirror 53 and movable mirror 54 is formed and the automatic original feeding mechanism is operated. The automatic original feeding mechanism may also be constructed so that even if the copy button is not depressed, it detects the original placed on the original insertion guide 55 by an unshown means to automatically start.

In the present embodiment, the microswitch 77 is closed and opened by movement of the original discharge tray, but of course, it is also possible to close and open the microswitch 77 by movement of the original insertion tray 55 depending on the position whereat the microswitch 77 is disposed.

Also, in the present embodiment, the original insertion guide and the original discharge tray are constructed so that both of them may be rotated so as to be substantially coincident with the upper surface of the machine body, whereas it is also possible that one of them is fixed while the other is made rotatable, thereby providing the same function as the above-described function.

With the above-described construction, if the plane formed by the original insertion guide 55 and the original discharge tray during non-use of the auto feeder is formed at a position at least not higher than the original supporting table 1, such guide and tray will form no hindrance when particularly a three-dimensional original such as a book or the like is placed on the original supporting table 1.

Moreover, such guide and tray may be used as a working table on which originals or copy paper or small articles (Hotchkiss and other small articles) used for ordinary office works may be placed. Also, such guide and tray performs the function as the cover for the auto feeder portion and covers the auto feeder portion during non-use thereof, thereby protecting the auto feeder portion and preventing the user from inadvertently touching the auto feeder portion. Further, clips or the like are prevented from dropping into the auto feeder portion, and there is no fear that an operation of the machine effected without noticing the dropping of the clips or the like leads to an accident, or there is no necessity of making a useless effort to remove the clips or the like.

Also, by making the sheet original insertion guide 55 and the original discharge tray 71 into such a size as to project from the machine body, it is possible to make said plane large independently of the size of the machine body and thus readily obtain a sufficiently large plane as a working table.

Moreover, depending on whether the original insertion guide or the original discharge tray is placed in a position for use or a position for nonuse, change-over can be automatically effected between the copying by the original (automatic) feeding using the auto feeder portion and the copying using the original supporting table 1 and therefore, the operation is simple and easy to understand to the user and wrong operation does not occur.

The fixing station 26 will now be described in greater detail with reference to Figure 7.

Referring to Figure 7, a fixing roller 101 and a pressure roller 102 are rotatably supported at their opposite ends by an upper side plate 103 and a lower side plate 104, respectively. The upper side plate 103 and the lower side plate 104 are pivotally mounted at one end thereof by a support shaft 105 and, at the other end thereof, a pressure force w is applied to the upper and lower side plates 103 and 104 by the action of three members, namely, a bolt 106 passing through the two side plates, a spring 107 surrounding the bolt 106 and a nut 108 compressing the spring 107 to create a repulsion force.This pressure force w is doubled in the side plate portions by the principle of the lever and, between the fixing roller 101 and the pressure roller 102, it acts as a total load W (W > w, and the linear pressure resulting from dividing W by the length of the roller is 20-50 kg/cm). This load W directly acts on plain paper P carrying a toner image T thereon and presses and fixes the toner image Ton the surface of the paper. Only a predetermined pressure is required for the fixation and, even if the number of copies per unit of time is increased by sheets of transfer paper being continuously moved while keeping a close interval therebetween, it will not affect the fixation. The fixing roller 101 is rotatively driven in the direction of arrow A by motor (not shown) through a gear (not shown) provided at one end of the fixing roller.The pressure roller 102 is rotated in the direction of arrow B by the friction force (of the roller 101 when paper P is not present between the rollers 101 and 102, and of the paper P when the paper P is nipped between the rollers 101 and 102). The paper P is moved in the direction of arrow by the rotation of the rollers 101 and 102, whereby the pressure fixation of the toner image T progresses.

That surface of the paper P which carries the toner image T thereon is urged against the fixing roller 101, and the opposite surface of the paper P is urged against the pressure roller 102.

By disposing the auto feeder and the pressure fixing device in combination as described above, a constant pressure is always applied to transfer paper to thereby fix the toner image on the transfer paper and, even if the number of copies per unit of time is increased by sheets of transfer paper being continuously moved while keeping a close interval therebetween, the fixation is not affected and thus, complete fixation can be ensured independently of the difference in speed between the copying using the auto feeder and the copying not using the auto feeder, and the necessity of preparing wasteful electric power is eliminated, thus reducing the power consumption of the copying machine. Further, a heat source is not required and therefore, the previously noted disadvantages do not occur. That is, there can be provided a copying machine in which the function of the auto feeder can be fully performed and which has few disadvantages.

Claims (5)

1. A dual mode copying machine having: an original supporting plate on which a thick original such as a book or the like may be placed, copy medium supporting means which can be enlarged to copy mediums of different sizes to copy original images of various sizes; and sheet original conveying means provided adjacent to said original supporting plate so as to be enlarged on that side of the machine body on which said copy medium supporting means is enlarged, substantially in coincidence with said enlargement, so that the conveyance and exposure of sheet-like originals larger than said original supporting plate is possible.

2. A dual mode copying machine according to Claim 1, wherein the sheet original supporting portion of said sheet original conveying means is pivotably constructed and part of said sheet original supporting portion projects outwardly of the machine body.

3. A dual mode copying machine according to Claim 2, wherein the selection of copy modes is controlled in response to the pivotal movement of said sheet original supporting portion.

4. A dual mode copying machine according to Claim 1, wherein the original exposure scanning speed by said sheet original conveying means is made higher than in the case where the original on said original supporting plate is copied, and said copying machine has pressure fixing means effecting the fixation by a pressure force for providing a predetermined fixation effect independently of the copying speed by the selection of copy modes.

5. A dual mode copying machine substantially as hereinbefore described with reference to Figures 5 to 7 of the accompanying drawings.