GB2125569A - A control system for controlling the copying process and the drive of a copying apparatus - Google Patents

Abstract

A control system is provided for controlling the copying process and the drive of a copying apparatus designed for copying at least two sizes of original. The original on slide 2 is seamed and the image transferred to an intermediate- image carrier drum 8, on which a toner image is developed and is subsequently transferred to a copy sheet and fixed thereon. A processor controls the drive and the switching-on and-off of all units, the rear edge of the entering copy sheet being detected by means of a sensor 1 and input into the processor for limiting the scan of the original, e.g. by limiting the travel of slide 2. The sheets are fed from a cassette 21. For copying an original of different size an individual sheet of paper can be fed via an auxiliary insertion unit 9. <IMAGE>

Description

SPECIFICATION A control system for controlling the copying process and the drive of a copying apparatus The invention relates to a control system for controlling the copying process and the drive of a copying apparatus designed for copying at least two sizes and where an original in registration is delineated in strips and transmitted to an intermediateimage carrier, on which a toner image is developed and is subsequentlytransmitted to a delivered sheet of paper and is fixed thereon by means of a processor which controls the drive and the switching-on and -off of all units.

In the case of copying apparatuses providing the possibility to copy different sizes, for example a DlN-A4 size and a DIN-A3 size, the control is usually designed forthe maximum size so thatthe copying process always occurs at the same operating speed, even if the smaller size is copied. This results in unnecessarily long times for a work cycle involving the smaller size. In addition, there is a risk toner being transmitted to the intermediate-image carrier, causing the copying apparatusto be contaminated, and this applies particularly to the copying of the smaller size.

The task underlying the invention is to design the control system of a copying apparatus suitable for at least two sizes in such a way that as high an operating speed as possible is attained for each size and that the risk of the apparatus being contaminated is reduced.

This problem is solved in thatthe rear edge of the entering sheet of paper is detected by means of a sensor and is input into the processor for limiting the copying process and the delineation ofthe original.

This ensures that the entire process sequence is automatically controlled by means of the control system as a function ofthe respective size, so that optimum operating times for each size are achieved.

Since the control is effected automatically in dependence on the size of the entering sheet of paper, any incorrect handling by an operator is impossible.

Furthermore, bythis means it is also possible to copy sizesbetweenthe maximum sizeandthe minimum size at the respectively most favourable operating speeds.

In an advantageous constructional form of the invention,there is provided forthe original to be put in registration a slide which has a driving motorwhich is mechanically separate from a main driving motor and is controlled by the processor and which drives a position potentiometer for detecting the slide position and has a servo-control which controls the return movement from the size-dependent end position according to a pre-set acceleration and delay section.

This ensures that a maximum return speed of the slide will be automatically in operation foreach size, without a sudden acceleration and, in particular, a sudden braking ofthe slide causing violent vibrations to occur in the copying apparatus. The same principle can also be realised if the original is stationarily put in registration and a movable objective with an exposure unit is provided. In order to obtain an exact synchronisation ofthe slide and the other elements in this constructional form, provision has been furthermore made for a synchronisation to be effected between the main driving motor and the driving motor ofthe slide during the advance movement thereof by a frequency and phase comparison of the two driving motors, the frequency of the main driving motor being the reference frequency.

In orderto allowthecopying process to be immediately interrupted in dependence on the rear edge of an entering sheet of paper, if possible without any dead sections, provision has been made in an expedient development of the invention for the sensor detecting the rear edge of an entering sheet of paper to be arranged in a length ofthe distance to be travelled by the sheet of paper, upstream of a transfer corona which transfersthe toner image on the sheet of paper, that corresponds to the length of the circumference of a drum serving as the intermediate-image carrier between the point at which an image of the original is formed on this drum and the transfer corona. This ensures that a charge pattern and a toner image are produced on the intermediate-image carrier only to such an extent as can be accommodated by the size.

In a further advantageous development of the invention, provision has been madeforthe copying apparatus to be provided with an auxiliary insertion deviceforfeeding an individual sheet of paper, which device, while by-passing a main insertion device, leadstotransporting elementsandtoa sensor triggering the commencement of a work cycle and which contains a sensor detecting the presence of the sheet of paper and triggering a starting signal in the processor. By this means, it is possible to feed an.

individual sheet of paper, on which a copy is to be produced, via a by-pass, there being no need for the operator to supervise which size the sheets of paper which happen to be in the apparatus have and to effect any changes. It is virtually possible to introduce a sheet of paper of any length between the maximum size and the minimum size thereof. Forthis individual sheet of paper, too, there is brought about copying at maximum operating speeds without increasing the risk of contaminating the apparatus.

Fu rtherfeatures and advantages of the invention will emerge from the following description of a constructional form illustrated in the drawings, in which FIGURE 1 shows a control system for a copying apparatus equipped with a mobile slide for an original to be put in registration, and FIGURE 2showsan acceleration and delay section for the mobile slide during the advance and return movements thereof.

The top ofthe copying apparatus shown in Fig. 1 is formed by a slide 2 which substantially consists of a glass plate, on which the original to be copied is placed in registration in a specified position. The slide 2 can be moved to the end positions shown in dash-dotted lines in Fig. 1,the right-hand position in the drawing corresponding to a starting position atthe commencement of an advance for a copying operation and the position shown on the left-hand side of Fig. 1 corresponding to the end position of the slide for copying the maximum size. The slide 2 is driven from a drive motor 5 by means of a chain drive ortoothedbelt drive orthe like not shown.The drive motor5 furthermore drives a position potentiometer 6, with which comparison potentials are associated in a process 4, so that the respective position ofthe slide 2 isthusdefinedthroughtheposition potentiometer6.

The original in registration on the slide 2 is exposed in strips by means of an exposure lamp 13 and an image thereof is formed, in a corresponding stripwise manner, via a glass fibre objective 14 on a drum 8 which serves asthe intermediate-image carrierand the circumference of which is provided with a photo-conductive semi-conductor. In the direction of rotation ofthedrum 8 upstream of the exposure point determined by the glass fibre objective there is associated with the circumference of the drum a charging corona 15, which causes a uniform electrostatic potential to be produced on the circumference ofthe drum 8 which, by way of exposure via the glass fibre objective 14, is discharged to form a charge pattern corresponding to the original to be copied.In the direction of rotation of the drum 8 there follows afterthe glass fibre objective 14 a developing unit 16 with a magnetic roller, by means of which there is produced a toner image on the drum 8 corresponding to the charge pattern. Further in the direction of rotation ofthe drum 8, there follows after the developing unit 16 a transfer corona 7, with the aid of which the toner image is transferred from the drum 8 to a delivered sheet of paper. The detachment of the toner image and of the sheet of paper from the drum is brought about by a detaching corona 17 further downstream. Downstream of the detaching corona 17, the sheet of papertogetherwith the toner image is transported by means of a transporting unit 18, formed by several belts, to a fixing unit 19 which fixes the toner image on the sheet of pauper.Subsequently, the sheet of paperwith the fixed toner image is released from the copying apparatusthrough a releasing roller pair 20. The sheets of paper arefed to the copying apparatus by means of a main insertion unit, which consists of a cassette 21 containing a stack of sheets of paper and from which the individual sheets of paper are removed by several insertion segments 22, which are arranged on a common shaft, and are fed to a transporting roller pair 11, which is arranged upstream ofthe transfer corona 7.

The insertion segments 22 andthetransporting roller pair 11 can be connected through couplings to a main drive which is driven by a main drive motor 3.

The main drive motor3furthermore drives, through a chain drive not shown, the drum 8, the magnetic roller ofthe developing unit 16, the transporting unit 18, the fixing unit 19 and the withdrawal roller pair 20. The main drive motor3furthermore drives a cleaning unit 23 which comprises an extinguishing lamp 24, which is associated with the drum 8, and which is destined for removing from the drum anytoner material that has not been transferred by the drum 8 and to clean the latter.

The drive motor5 ofthe slide 2 and the main drive motor 3 are mechanically separated. Synchronous running of the two drive motors during the copying process is controlled by a micro-processor 4 by means of a frequency and phase comparison. Forthis purpose,the main drive motor3 is provided with a frequency generator 25, whose frequency serves as the reference frequency.

The micro-processor 4 controls the individual drives as well as the switching-on and off of the individual units as afunction of a signal fed thereto. To the micro-processor4there is linked an input and output unit 26 which allows, for example, the brightness of the exposure and, in particular, the number of the desired copies two be chosen as well as a starting signal to be given. On account of the starting signal from the input and output unit 26, the micro-processorstarts the main drive motor3 and furthermore switches on an extinguishing lamp 33, which is directly adjacent to the exposure point ofthe glass fibre objective 14.

Before a paper insertion is effected, a sensor 27 associated with the cassette 21, for example a light barrier, checks whether a cassette 21 is present and whether sheets of paper are contained in this cassette.

If this is the case, then the micro-processor 4 switches the coupling of the insertion segments 22 so thatthese rotate through a pre-setangularvalueand guide the front edge of the sheet of paper beneath a sensor 1 which is also designed, for example, as a light barrier.

When the paperfrontedge reachesthesensor 1,this sensor gives a signal to the micro-processor 4 which thereupon switches on the drive motor 5 of the slide 2 so thatthe latter moves to the starting position (Fig. 1, right-hand side). The position potentiometer signals to the micro-processor4thatthe slide 2 has reached the starting position, whereupon the drive motor 5 is switched overto advance. On the slide 2 there are provided actuating elementsfortwo switches 28 and 29 which are arranged in the copying apparatus and which are actuated in dependence on the slide position. The actuating elements ofthe slide are expediently fastened to the slide so as to be adjustable in the direction of displacement.On account of the signal from the switch 28, the micro-processor switchyes the extinguishing lamp 13 off and simultaneously switches the charging corona 15 and the exposure lamp 13 on. With a short delay, the coupling ofthe insertion segments 22 is furthermore actuated in such a way that these move the front edge of the sheet of paperagainstthetransporting rollerpairll. Following another short distance, the switch 29 is actuated, on account ofthe signal of whichthe micro-processor switchesthecouplingofthetransporting roller pair 11 on, whereafterthe synchronous running of the slide 2 and the sheet of paper as well as the drum 8 and the other elements commences.

The switch 29 furthermore causes counters inside the micro-processor to be set to different values which, with a certain delay, determined by pulses from the main drive motor3 emitting a reference frequency, switch on the transfer corona and the detaching corona. Following another delay, a sensor 30 of the transporting unit 18 is activated, which detects whether the sheet of paper with the toner image has indeed been detached from the drum 8 and is correctly transported further. With a further delay, there is then activated a sensor 31 which may be, for example, a known ring switch associated with the releasing roller pair 20 and which serves for checking the discharge ofthe sheet of paper.

Following a pre-settransporting distance travelled by the transporting roller pair 11, which may, for example, also be determined by pulses from the main drive motor 3, the sensor 1 is activated in order to detectthe rear edge of the entering sheetofpaper and to signal itto the micro-processor 4 which thereafter selects a switching-off program, which is somewhat different for producing a single copy or multiple copies. However, in any case, the drive motor 5 ofthe slide is switched from advance to return. The sensor 1 gives a pulse to a microprocessorcounter,which has been set bythe input and output unit 26, re-setting this counter.As long as this counter has not been re-setto zero, a repetition program is in operation, during which the slide is brought into its starting position and the paper removal by means of the insertion segments 22 is once more started. Furthermore, the extinguishing lamp 13 is switched on so as to prevent, if possible, anytransferoftoner material to the zone ofthe drum 8 which is left between the individual images. In this connection, it is of importance thatthe sensor 1 and the exposure point should be at the same distance from the charging corona 7. Thereafter, the operation cycles triggered by the switches 28 and 29 are carried out again in the described manner.

When the micro-processor 4 counter, which has been set bythe input and output unit 26, has been re-settozero bythe pulses emitted by the sensor 1, there is launched, controlled by the sensor 1,a switching-off program which returns the slide into the central position shown in solid lines in Fig. 1.

Furthermore, the charging corona 15 is switched off.

With appropriate delays, each of which corresponds two a distance,thetransfercorona7and the detaching corona 17 are switched off. With a further delay, the sensor 30 is then switched off so as to prevent the unjusified signalling of an accumulation of paper.

Furthermore, there is activated, with a further delay, the switch 31 which is actuated by the rear edge ofthe sheet of paper and which switches the main drive motor3 off.

The drive motor 5 ofthe slide 2 is provided with a servo-control which gives the acceleration and delay section, shown in Fig. 2, forthe movement of the slide 2. From any position which is established by the rear edge ofthe sheet of paper, which rear edge is detected bythe sensor 1,the slide starts, according to the arrows taken from left to right, to a central path with a specific acceleration and is thereafter braked with a specific delay, so th at the necessary distance is travelled at a maximum speed, without however any jerky accelerating and/or delaying forces arising, which might lead to a vibration ofthe copying apparatus.The advance movementfrom the start commences with a certain acceleration and is then controlled at a constant speed which is synchronised by a frequency and phase comparison between the main drive motor 3, which gives the reference frequency, and the speed-sensitive frequency of the drive motor 5. Thereafter, braking is effected with a pre-set delay.

Due to the fact that the rear edge of an entering sheet of papertriggersa repetition program control and a switching-off program control, the optimum operating speedsforthe individual sizes are attained, without any special settings having to be taken care of by the operator. It is sufficient if a cassette 21 of the appropriate size is introduced.

Furthermore, it is rendered possible, independently ofthe paper size in the cassette 21, to feed an individual sheet of paper, which sheet may be different in size; optimum operating speeds being achieved here, too, and the risk of contamination being simultaneously reduced. Forthe introduction of an individual sheet of paper there is provided an auxiliary insertion unit 9 thatforms a by-pass and comprises an auxiliary insertion roller pair 32 which can be connected with a coupling to the drive driven from the main drive motor3viathe micro-processor 4. The presence of a sheet of paper in the auxiliary insertion unit is detected by a sensor 12 and is signalledtothe micro-processor4which then starts, with a certain delay, the auxiliary insertion rollers 32 by engaging the coupling. The auxiliary insertion rollers 32 guide the inserted sheet of paperto the sensor 1 which gives a corresponding starting signal to the micro-processor 4, whereafterthe described copying process takes its course as with an individual copy with the difference that, instead ofthe insertion segments 22, the auxiliary insertion rollers 32 are once more actuated for a short time by the switch 28 in orderto insertthe paper front edge into the transporting roller pair 11. In this case, too, the rear edge of the inserted sheet of paper then controls the switching-off program, as has been described above.

Claims (6)

1. A control system for controlling the copying process and the drive of a copying apparatus designed for copying at leasttwo sizes and where an original in registration is delineated in strips and is transferred to an intermediate-image carrier, on which a toner image is developed and is subsequent lytransmittedto a delivered sheet of paperand is fixed thereon by means of a processorwhich controls the drive and the switching-on and off of all units, characterised inthatthe rear edge of the entering sheet of paper is detected by means of a sensor (1 ) and is input into the processor (4) for limiting the copying process and the delineation ofthe original.

2. Acontrol system as claimed in Claim 1, characterised in that there is provided for the original to be put in registration a slide (2) which has a drive motor (5) which is mechanically separated from a main drive motor(3) and is controlled bythe processor (4) and which drives a position potentiometer (6) for detecting the slide position and which has a servo-control, which controls the return from the size-dependent end position according to a pre-setacceleration and delay section.

3. A control system as claimed in claim 1 or 2, characterised in that a synchronisation between the main drive motor (3) and the drive motor (5) ofthe slide (2) is effected during the advance by a frequency and phase comparison of the two drive motors, the frequency ofthe main drive motor (3) being the reference frequency.

4. A control system as claimed in one of Claims 1 to 3, characterised in that the sensor (1 ) detecting the rear edge of an entering sheet of paper is arranged upstream of a transfer corona (7), which transfer the toner image to the sheet of paper, in a length of the distanceto betravelled bythesheetofpaperthat corresponds to the length of the circumference of a drum (8), serving as the intermediate-image carrier, between the point on which an image ofthe original is formed on this drum (8) and the transfer corona (7).

5. A control system as claimed in one of Claims 1 to 4, characterised in that the copying apparatus is provided with an auxiliary insertion unit (9) for feeding an individual sheet of paper, which unit, while by-passing a main insertion unit (10), leads to transporting elements (11) and to a sensor (1) triggering the commencement of a work cycle and which comprises a sensor (121 detecting the presence of a sheet of paper and triggering a starting signal in the processor (4).

6. A control system for controlling the copying process and the drive of a copying machine substantially as herein described with reference to Figure 1 of the accompanying drawings.