Device For Cutting A Rolled Medium

Abstract

In a copying apparatus or the like using a rolled medium, a device for cutting the rolled medium into a predetermined length comprises cutter means, cutter operating means, rolled medium conveyor means and a conveying path both provided rearwardly of the cutter means. The device further includes second detector means operated by the rolled medium when a predetermined time T.sub.2 has elapsed after cutting, and first detector means operated when a time T.sub.1 determined by the length of the medium cut off has elapsed after the cutting. The first and second detector means are located so as to satisfy the relation that T.sub.3 > T.sub.1 > T.sub.2, where T.sub.3 is the time required for one cycle of operation. The cutter means is operated to effect an additional cutting operation when the first detector means properly operates but the second detector means does not do so.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a roll cutting device in copiers, printers or the like which employ a rolled printing medium, and more particularly to a roll cutting device which can detect any unsuccessful cutting operation and can correspondingly accomplish additional cutter operations.

2. Description of the Prior Art

In a copying machine or the like using a roll of copying medium, it is usually the practice to set a predetermined format of medium (such as format A or B), then select a predetermined length and operate a cutter in accordance with a signal representing the selected length to cut the medium into the predetermined length, thereafter convey the cut medium to a subsequent process station. The cutter operation is stable for restricted types of the medium and under restricted ambient conditions, whereas if the types (especially, thickness) of the medium and the ambient conditions (especially, high humidity) are varied, cutting errors would inevitably occur with an increasing wear of the cutter edge. Moreover, unsuccessful cutting occurring in high-speed copying machines would cause the medium to be conveyed in the form like a chain or would result in jamming. Especially, in an electrophotographic copying machine which generally includes heating means for fixing a formed image on the medium at the last stage of the process, the medium stopped in the heating means would lead to a danger of firing and, if the medium is continuous in the form of a chain, it would impart damages to the apparatus itself.

SUMMARY OF THE INVENTION

The present invention provides a device which can quickly detect any unsuccessful cutting to thereby prevent occurrence of the above-noted possible dangers and further can effect an additional cutter operation or operations. To achieve this, the present invention employs a second detector switch provided in the path of a copying medium rearwardly of the cutter and operated by the copying medium in a time T.sub.2 after a cutting operation, and a first detector switch operated in a time T.sub.1 after the cutting operation, the time T.sub.1 being determined by the length of the medium cut off. The first and second detector switches are relatively located so as to always satisfy the relation that T.sub.3 > T.sub.1 > T.sub.2, independently of the size of the medium (T.sub.3 being the time required for one cycle of operation. Thus, the cutter is caused to effect an additional cutting operation when the first detector switch properly operates but the second detector switch does not properly operate .

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become fully apparent from the following detailed description thereof taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic representation of an electrophotographic copying apparatus to which the present invention is applied;

FIG. 2 is a schematic view showing the construction and arrangement according to an embodiment of the present invention;

FIGS. 3 (1) and (2) are diagrams of the electric circuits in respective embodiments;

FIG. 4 is an elevational view of the drive system therefor;

FIG. 5 is a plan view of the drive system;

FIG. 6 is a front view of another embodiment using a modified arrangement of control switches and cams;

FIG. 7 diagrammatically shows the electrical connection of the present invention utilizing an electric timer circuit;

FIG. 8 shows the arrangement of the control switches and cams in the FIG. 7 embodiment;

FIG. 9 is a front view of the detector switch;

FIG. 10 is a perspective view of the detector switch; and

FIG. 11 shows a modified form of the detector switch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, there is shown an electrophotographic copying apparatus provided with the device according to an embodiment of the present invention. An original carriage 1 is mounted on top of an apparatus body 24 and supports thereon an original O to be copied. While the original may be scanned in any known manner, the illustrated example employs such a system that a first mirror 4 and a second and a third mirror 5 and 6 are moved in parallelism to the original carriage 1 at the speed ratio of 1 : 1/2 whereby the optical path from a lens 7 to the surface of the object may always be maintained at a predetermined length. A lamp a for illuminating the object and a reflector 3 are secured to a first mirror base 4-1 (FIG. 2) so that the image from the object may be directed via the mirrors 4, 5, 6 and through the lens 7 and further reflected by a stationary mirror 8 for projection upon a photosensitive drum 11.

The electrophotographic process illustratively adopted herein is disclosed in Applicant's Japanese Patent Publications Nos. 23910/1967 and 24748/1968. More specifically, the photosensitive drum 11 is rotatably on a horizontal shaft 11-1 fixed to the apparatus body, in the direction of arrow and at a velocity equal to that of the first mirror 4 (in the case of 1 : 1 magnification), and is subjected to corona discharge from a charger 10 and thence subjected to simultaneous application of image light from the object O and AC corona discharge by a simultaneous exposure and discharge means 9; whereafter the drum 11 is subjected to an overall exposure by a lamp 21 to form thereon an electrostatic latent image, which is then brought to a developing station 12 and made into a visible dust image by a so-called sleeve type developing device formed by a non-magnetic cylinder containing therein a magnet; thence the dust image reaches an image transfer station where a web of paper P fed in synchronism with the movement of the dust image on the drum is brought into contact with the dust image while a corona is applied from a corona discharger 14 to the back side of the paper P to transfer the dust image from the drum to the paper P; thereafter the paper P is separated from the drum surface by suction force at separator means 13 and conveyed on a belt 18 to pass below a heater 19 for heating and fixing the dust image on the paper P; and finally the paper is discharged through a set of discharge rollers 22 onto a tray 23.

After the image transfer, the drum 11 reaches cleaner means 20, whose blade 20-1 of polyurethane rubber or like material wipes the surface of the drum to remove any residual toner thereon. The toner thus removed is discharged in one direction by a discharge screw 20-2 at the lower part of the cleaner.

The transfer paper P may be in the form of a roll 17, from which the paper is fed by a set of feed rollers 15-1 and further delivered to the image transfer station by a set of timing rollers in synchronism with the image on the drum. The web of paper P is then advanced over a predetermined length, whereupon it is cut by a cutter 16.

The present invention is applicable to an apparatus which uses such a roll of paper as described above, and embodiments thereof are shown in FIGS. 2 and 3.

The web of paper unwound from the roll 17 is first passed over an uncurling roller 15-3, and then passed between feed rollers 15-1 while th leading edge of the paper is uniformly trimmed by the chuck cutter 16, whereupon the paper is temporally stopped there and ready for copying. Thereafter, for example, in response to a paper feed signal from a paper feed start switch SW1 actuated by a cam C3, first the feed rollers 15-1 and then the rollers 15-2 are rotated, the latter being in synchronized relationship with the formed image on the drum, whereby the paper P is fed while the mirror train in moved horizontally (leftwardly in the drawing) in response to a signal from a print button or the like provided separately.

The drive system for the mirror train is shown in FIGS. 4 and 5. The first mirror base 4-1 and the second mirror base 5-1 are journalled for smooth movement on rails 25 each fixed to the apparatus body 24. A driving wire 36 has one end thereof secured to the apparatus body at a point C and extends via a pulley 39 rotatably mounted on the second mirror base 5-1 by means of a shaft 40, and via a pulley 38 journalled to the apparatus body, and is wrapped for several turns about a drive pulley 31, wherefrom the wire 36 extends in a cross fashion and passes over a pulley 37 and said pulley 39 to an opposite point D, where the other end of the wire is secured to the apparatus body. A point E on the first mirror base 4-1 is connected to the wire 36. Thus, when the wire 36 is driven at a velocity V in the direction of arrow, the first mirror base 4-1 (i.e. mirror 4) is driven at the same velocity V, followed by the leftward movement of the second and third mirrors 5 and 6 at the speed of V/2 due to the principle of the running block.

FIG. 5 schematically shows a top plan view of the driven system. The drive from motor M is transmitted via gears 29 and 28 to the drum 11 and further to gears 30 and 32. When a clutch CL-1 is electrically operated, the mirror train driving pulley 31 is driven through gears 29, 30, clutch CL-1 and shaft 41 in the direction of arrow indicated in FIG. 4, thus moving the mirrors leftwardly at the velocity V. Next, when the clutch CL-1 is disconnected and the clutch CL-2 is operated, the shaft 41 and pulley 31 are reversely driven through gears 29, 30, 32, clutch CL-2, sprocket 34, chain 35 and sprocket 33, at a velocity V' determined by the gear ratio, thus reverting the mirrors rightwardly.

In the electric circuit shown in FIG. 3, a stop switch SW4 and a reversing switch SW5 are operated by an actuator 27 provided beneath the first mirror base 4-1. In the normal stop position (rightmost end position) of FIG. 4, the switch SW4 is opened by the actuator 27 so that both clutches CL-1 and CL-2 are in their OFF positions. When the print button PB is depressed, the clutch CL-1 is operated to move the mirror train leftwardly as already described, so that the mirror train scans the object while it directs the object image to the drum 11. When the actuator 27 is disengaged from the stop switch SW4, this switch is closed to permit the clutch CL-1 to continue its operation even if the print button PB is released.

On the other hand, when the mirror train comes to the leftmost end position until the actuator 27 is engaged with the reversing switch SW5, the switch SW5 is closed at its contact b to energize a relay RL-A, whose contact a-1 and accordingly the clutch CL-1 is thus disconnected, whereupon the relay RL-A self-holds by its contact 2--2 and has its contact a-3 closed, thus operating the clutch CL-2 to return the mirror train rightwardly until the actuator 27 opens the stop switch SW4. Thereupon, the relay RL-A and clutch CL-2 are disconnected to complete one cycle. Further, a contact a-5 serially connected with the print button PB is inserted to release the self-hold of the relay RL-A even if the print button PB is depressed in the open position of the switch SW4.

In the arrangement described above, a second detector switch SW3 is provided at an intermediate point between the cutter 16 and the image transfer station 14, as shown in FIG. 2. For the purpose of illustration, let L be the length of the path traversed by the paper from the cutter 16 to a point B in the image transfer station, AB be the circumferential length from the exposure point A on the drum 11 to the point B in the image transfer station. If AB = L, it will be possible to operate a cutter operating solenoid SL concurrently with the operation of the mirror train reversing switch SW5. Thus, the reversing switch SW5 can also serve as a cutting command switch SW1.

It will thus be seen that depression of the print button PB closes the clutch CL-1 to move the mirror train leftwardly while scanning the object O and projecting the reflected image thereon upon the drum 11 via mirrors 4, 5, 6, lens 7 and mirror 8, and concurrently therewith, the paper P is fed in by paper feed rollers 15-1, 15-2. Then the actuator 27 changes over the reversing switch SW5 to its contact b to disconnect the clutch CL-1 and operate the clutch CL-2, whereby the mirror train reverses its stroke while the contact a-4 of the relay RL-A is changed over to the contact a to charge a capacitor C, whose charging current energizes the solenoid SL to operate the cutter 16 so as to cut the paper P into a predetermined length. When the paper P is properly cut, the sheet of paper thus cut off will pass by the second detector switch SW3 to change over this switch to its contact b, whereafter the actuator 27 opens the stop switch SW4, thus completing one cycle. Thereupon, the contact a-4 shifts back to its contact b to cause the capacitor C to discharge through a circuit of (SW3-b) - (a-4-b) and a resistor R.

However, if the paper cutting is unsuccessful, the paper P will remain astride the cutter 16 so that the paper P is still present on both sides of the cutter, and thus the second detector switch SW3 is maintained closed at the contact SW3-a by the paper to thereby keep the cutter ready for an additional cutting operation. On the other hand, the detection of unsuccessful cutting and the additional cutting operation must take place during one cycle and prior to a subsequent cycle. Therefore, in the case of FIG. 3 (1) for the illustrated embodiment, the switch SW4 coming to the final position in one cycle is made to act as a second detector switch for imparting an additional operation command. When the switch SW4 is opened at the final position, the contact a-4 of the relay RL-A is connected with the contact b to form a circuit of (a-4-b) - (SW3-a), through which the capacitor discharges to energize the solenoid SL and resume the cutting operation.

While in the foregoing the stop switch SW4 has been made to act as a first detector switch, if it is desired to make the point of detection time take place earlier, then a first detector switch SW2 may be provided at a spatial point corresponding to the time before the reverted mirror train comes to the final position of the stop switch SW4, i.e. at an intermediate point between the switches SW5 and SW4. However, since the return velocity V' of the mirror train is higher than the normal forward velocity V thereof, the relative positions of the switches SW3 and SW2 must be determined so as to satisfy the relation that T.sub.3 > T.sub.1 > T.sub.2, where T.sub.2 is the time required for the trailing edge of the paper P to pass through the second detector switch after the reversal of the mirror train, T.sub.1 is the time required for the mirror train to pass through the first detector switch SW2, and T.sub.3 is the time required for one reciprocal cycle of the mirror train.

The circuit in the case described just above is shown in FIG. 3 (2). The first detector switch SW2 operable in a predetermined time T.sub.1 after a cutter operation to start an additional cutting operation of the cutter, and the second detector switch SW3 for detecting whether the paper has been cut properly or not, are set so that they are respectively operated upon lapse of time T.sub.1 and T.sub.2 after the operation of the cutter and that the relation T.sub.1 > T.sub.2 is satisfied, namely, so that the switch SW3 is opened after the time T.sub.2 (>T.sub.1) when proper cutting has been done. The additional cutter operation is accomplished with the charge from the capacitor C being supplied to the solenoid SL through the first detector switch SW2-b and the second detector switch SW3-a. It is to be noted that the time T.sub.2 is constant once the switch positions are determined, whereas the time T.sub.1 is variable with the length of the original image (i.e. the length to be scanned).

In the embodiment described above and shown in FIG. 2, the switch for the reciprocation of the mirror train and the first detector switch SW4 (or SW2) are all disposed in the path of travel of the mirror train, but the construction and arrangement as shown in FIG. 6 is also feasible.

As shown in FIG. 6, a camming plate 42 rotatable in the direction of arrow at the velocity equal to the velocity V of the mirror train may be mounted as on a mirror driving pulley shaft 41, and may be provided with cams C1, C2 and C3. Switches SW1, SW2, SW3, SW4 and SW5 may also be provided. In scanning an object, some auxiliary running distance 1.sub.2 is usually necessary to prevent the overshot of velocity arising from the inertia of the mirrors and the like. Therefore, the mirror train travels over a distance 1.sub.2 + 1.sub.1 which is longer than the actual image length, and accordingly, the feeding of paper P must start later by 1.sub.2 than the start of the mirror train. For this purpose, there is provided a paper feed starting switch SW1. When the cam C3 actuates the switch SW1, the paper feed is started, and when the cam C3 engages the reversing switch SW5, the clutch CL-1 is disconnected but the clutch CL-2 is operated and the cutter is operated at the same time. The length of the paper sheet thus cut off is equal to the length of the original image, as is the case with AB = L in FIG. 2. The cam C1, which serves to actuate the first detector switch SW2, is designed so that it is operative in the return stroke only and not in the forward stroke.

Although the detector switches have been shown as microswitches, they may alternatively be photodetector switches comprising a combination of a light source and a photoelectric element.

The above-described embodiments are arranged to accomplish an additional cutting operation when unsuccessful cutting has been detected, but there may be such situations that the twice repeated cutting operation is no sufficient to cut the paper.

FIG. 7 shows a multi-cutting system which utilizes a CR timer circuit for repeating the cutting operation more than twice until the paper is completely cut off.

In FIG. 7, the stop switch SW4, when in its normal stop position (rightmost end position), is closed at its contact SW4-a by the actuator 27 and both clutches CL-1 and CL-2 are disconnected. Depression of the print button PB energizes a relay RL-C, whose contact C-2 is thus shifted to the contact a to supply the power to the clutch CL-1, thereby moving the mirror train leftwardly to scan the object and expose the drum 11 to the object light. When the actuator 27 is disengaged from the switch SW4, this switch is changed over to the contact SW4-b but the relay RL-C self-holds by its contact C-1, thus permiting the clutch CL-1 to continue its operation even if the print button is released.

When the mirror train reaches its leftmost end position so that the actuator 27 engages the switch SW5 to shift the latter to its contact SW5-b, the reversing clutch CL-2 is operated through the relay RL-C with its contact C-1 opened, the closed contact C-2-b and closed switch SW4-b, to thereby return the mirror train rightwardly and cause the actuator 27 to bring about the open switch SW4-a, thus disconnecting the clutch CL-2 and stopping the mirrr train. Thus, one cycle is completed.

Where the switch SW5 for producing a reversing signal is to serve also as the cutting command switch, the switch SW5-b is used for the switch SW6-d (hereinafter referred to as SW5-d). When the switch SW5-d is closed, i.e. when the mirror train begins to revert, the cutting solenoid SL is operated and by that time, the paper P has already been advanced to the point B, i.e. by a length satisfying the relation L = AB in FIG. 2. In this instance, a cutting command switch SW6 operable simultaneously with the reversing switch SW5 may be provided in the manner as shown in FIG. 6, the switch SW6 serving also as the switch SW5. The arrangement described just above is substantially identical in operation with the previously described embodiments.

A CR timer circuit is combined with the above-described circuit of the cutting solenoid SL, and such circuit is controlled by the second detector switch SW3 in the paper feeding system so that cutting operation may be repeated until the web of paper from the supply roll is completely severed. As soon as the solenoid SL is operated with the switch SW5-d closed as described above, a relay RL-D is energized through a diode D to close its contact d-1. At that time, the cut paper still rests on the second detector switch SW3 so that the relay RL-D remains energized even if the switch SW5-d is open, but the relay RL-D becomes deenergized when the leading edge of the paper sheet has passed by the switch SW3.

If the paper should fail to be cut well and the switch SW3 continues its closed position, the relay RL-D will self-hold but will be disconnected from the solenoid SL by the diode D, thus permitting the cutter 16 to be returned to its initial position by a spring.

As soon as the relay RL-D is energized due to the above-described closed position of the reversing switch SW5.varies.d, the contact d-2 thereof is open to allow a current to flow to the capacitor C and to the base of transistor Tr, thus boosting the terminal voltage of the capacitor C and also boosting the terminal voltage of the relay RL-B in the transistor circuit. Such voltage boost continues until the second detector switch SW3 is opened (i.e. paper is severed) and the relay RL-D is reset.

If during that while the paper has been severed, the second detector switch SW3 will be opened by the trailing edge of the severed paper sheet after the aforesaid predetermined time T.sub.1 has elapsed (T.sub.1 = L/S, where S is the velocity at which the paper is fed), so that the relay RL-D will be reset while the timer circuit is cut off. Thereupon, the contact d-2 is closed to cause the capacitor C to discharge through resistor R2.

If the paper could not be severed within the time T.sub.1 or more, the charge in the capacitor C will boost the maximum terminal voltage V.sub.1 of the exciting coil of the relay RL-B to a level exceeding its operating voltage V.sub.a (the relation V.sub.1 < V.sub.a being determined by the values of VR, R1, R2 and C), thus operating the relay RL-B to close its contact b-1 and energize the cutter operating solenoid SL for an additional operation of the cutter 16.

Thereupon, the contact b-2 of the relay RL-B is closed to cause the capacitor C to discharge its stored charge through the transistor base and resistors R1, R2. When the terminal voltage of the relay RL-B becomes lower than its reset voltage V.sub.b, the relay RL-B is reset to open the contact b-1, thus resetting the solenoid SL. Simultaneously therewith, the contact b-2 is also opened so that the terminal voltages of the capacitor C and relay RL-B start to rise.

If the paper has been served successfully by the above-described cutter operation, the trailing edge of the paper sheet will pass by the switch SW3 during the predetermined time T.sub.1 after the cutter operation, thus opening the switch SW3 to reset the relay RL-D and close its contact d-2, so that the capacitor C quickly discharges through the resistor R2 to cause the relay RL-B to reduce its terminal voltage in preparation for a subsequent detection. At this time, the values of VR, R1, R2 and C are determined so that the maximum terminal voltage V.sub.2 of the relay RL-B, unlike the previous case, is in the relation V.sub.2 < V.sub.2, if the time during which the contact b-1 is closed is TB. Further, by setting the resistance values of R1 and R2 so as to satisfy the relation TB .apprxeq. .DELTA. T, the relation V.sub.1 .apprxeq. V.sub.2 may be obtained so that the point of time at which the cutter is additionally operated at the time interval T.sub.1 after one cutter operation is always identical between a first, a second and subsequent additional cutting operation, and the values of VR, R1, R2 and C can be so set that the point of time for additional cutter operation comes earlier than in the case where V.sub.1 .noteq. V.sub.2. The reason is that when V V.sub.1 < V.sub.2, the point of time for a first additional cutter operation is delayed and when V.sub.1 > V.sub.2, the point of time for a second additional cutter operation is delayed.

Next, if the paper still stays on the second detector switch SW3 to maintain this switch closed even when the time T.sub.1 has elapsed after the forementioned first additional cutting operation, the terminal voltage of the relay RL-B will rise up to a level exceeding its operating voltage, whereupon the relay RL-B will be operated to effect a second additional cutting operation until the paper is completely severed. In this way, the additional cutting operations may be repeated automatically. Further, the contact d-3 of the relay RL-D is inserted in series with the copy button PB so that when the relay RL-D is being in operation, i.e. when the timer circuit for additional operation of the cutter is being in operation, the contact d-3 is opened to inhibit any subsequent copying operation. It is also possible to incorporate a device for operating a conventional time limit means by means of the relay RL-D contact so that during an unusually extended operating time of the relay RL-D or during successive occurrences of unsuccessful cutting operations, the time limit mean produce a signal to operate an indicator means such as lamp, buzzer or the like or to stop the paper feed.

FIG. 8 shows a mechanical similar in function to the embodiment of FIG. 6 but in which switches SW1, SW4 and SW5 are actuated by the cams C3, C3, and C2 on the camming plate 42.

FIG. 9 shows a specific form of the aforesaid second detector switch.

In a high-speed copying apparatus, paper cutting is usually effected without the paper being stopped. Since the cutter severs the paper web from one side edge thereof to the other side edge, the paper unavoidably tends to be cut obliquely with respect to the longitudinal axis thereof. FIG. 9 shows means for preventing such tendeny. In the process from the cutting station 16 via the timing rollers 15-2 to the image transfer station, a U-shaped curve E is provided by a guide plate 48 just before the rollers so as to bend the paper P into a U-shape along the inner bottom surface of the guide plate 48 and direct the paper to the timing rollers 15-2.

Concurrently with the signal for cutting the paper P, a brade is imparted to the feed rollers 15-1 to interrupt the paper feed temporally, whereupon the paper is cut. This ensures straight cutting of the paper. Since the timing rollers 15-2 are then in rotation, the paper is drawn somewhat upwardly from the lowest surface of the guide by these rollers, but upon severance the paper settles down at the lowest position from its own gravity.

If the cutting should be unsuccessful, a preceding sheet of paper will be drawn by the timing rollers 15-2 because the rollers 15-1 are braked, so that the paper will be tensioned as indicated by dotted line, thereby rotating a detecting lever 44 to cause an actuator 45 at one end of the lever shaft 43 to actuate the second detector switch SW3.

When the paper has been cut off, the tension in the paper is released to permit the detector lever to return to its original position, thus releasing the switch SW3.

In this instance, the detector lever 44 on the shaft 43 may be in the form of a lever 47 which is integral substantially along the entire width of the paper web as shown in FIG. 11 or a plurality of levers 44 may be provided in the direction of the paper width, whereby good detection may be ensured even if any unsuccessful cutting occurs with an uncut portion left in the side edge or center of the paper web.

Claims

We claim:

1. In a copying apparatus or the like using a rolled medium, a device for cutting the rolled medium into a predetermined length, said device comprising cutter means, cutter operating means, rolled medium conveyor means and a conveying path both provided rearwardly of cutter means, first detector means operated when a time T.sub.1 determined by the length of the medium cut off has elapsed after the cutting, and second detector means operated by said rolled medium when a predetermined time T.sub.2 has elapsed after severance of said rolled medium, said first and second detector means being located so as to satisfy the relation that T.sub.3 > T.sub.1 > T.sub.2, where T.sub.3 is the time required for one cycle of operation, said cutter means being caused to effect an additional cutting operation when said first detector means properly operates but said second detector means does not properly operate.

2. A device according to claim 1, wherein said cutter operating means includes a solenoid and a capacitor serially connected together, said solenoid being energized by a charging current flowing through said capacitor to effect a rolled medium cutting operation, and when the cutting operation is unsatisfactory, said second detector means detects it to cause said solenoid to effect an additional cutting operation.

3. A device according to claim 1, wherein said first detector means serves also as means for setting the final position of one reciprocal cycle of said copying apparatus or the like.

4. A device according to claim 2, wherein a timer circuit is parallel-connected with said solenoid so that, when a cutting signal does not come from said second detector means, first relay means energized upon energization of said solenoid continues its own energization to thereby charge said capacitor whose charging voltage is applied to second relay means, and when such condition continues longer than said predetermined time T.sub.2, said second relay means closes the circuit of said solenoid to effect a cutter operation, whereupon said capacitor, said second relay means, etc. are reset temporally, all these series of operations being again repeated in the absence of a rolled medium cutting signal.

5. A device according to Claim 1, further comprising timing roller means (15-1, 15-2) provided forwardly and rearwardly of said cutter means (16) in said rolled medium conveyor means, a guide portion (E) provided between said cutter means (16) and said timing roller means (15-2) to curve and direct said medium, and third detector means for braking said timing roller means (15-1) during the cutter operation for cutting the rolled medium widthwise thereof, to thereby detect that the curved portion of the rolled medium is tensioned as it is drawn by said timing roller means upon unsuccessful cutting.

6. A device according to claim 5, wherein said third detector means includes a detector lever (47) for braking the feed rollers (15-1) just preceeding the cutter during the cutter operation for cutting the medium straightly widthwise thereof, to thereby detect the entire width of the medium tensioned as it is drawn by said timing roller means (15-2) upon unsuccessful cutting, thus detecting a localized failure in cutting the medium.