US3682543A

US3682543A - Device for detecting the end of a roll of copy paper in a photocopying machine or the like

Info

Publication number: US3682543A
Application number: US4489A
Authority: US
Inventors: Minoru Iwamoto
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 1969-01-25
Filing date: 1970-01-21
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08
Also published as: GB1289671A; DE2003014A1; JPS497008B1

Abstract

A photocopy paper feed device control circuit contains a phototransducer which measures the intensity of light reflected from the surface of a roll of stored photocopy paper and thereby detects the trailing end of a strip of paper coiled on the storage roll. Said control circuit actuates a photocopy paper feed device only when a predetermined amount of paper remains to be fed. The distance between the measuring point of the phototransducer element and a paper cutting device is greater then that between two pairs of feed rollers disposed in a section following said cutting device so that the feeding of undersized pieces of photocopy paper is prevented.

Description

United States Patent 15 3,682,543 Iwamoto [451 Aug. 8, 1972 DEVICE FOR DETECTING THE END [56] References Cited OF A ROLL OF COPY PAPER IN A UNITED STATES PATENTS 3 OCOPYING MACIHNE OR THE 3,425,777 2/1969 White ..355/28 3,105,425 10/1963 Cerasani et a1. ..83/365 X [72] Inventor: Minoru Iwamoto, T k Japan 3,415,149 12/1968 Ziljberman et a1 ..83/365 X [73] Assignee: Kabushiki Kaisha Ricoh, Tokyo, Primary Examiner james M Meister Japan Attorney-Burgess, Ryan and Hicks [22] Filed: Jan. 21, 1970 57 ABS CT [21] Appl. No.: 4,489 1 A photocopy paper feed device control circuit contains a phototransducer which measures the intensity 1 Forelgll pp y Data of light reflected from the surface of a roll of stored Jan. 25, 1969 Japan ..44/5465 Paper and thereby detects the "ailing end of a strip of paper coiled on the storage roll. Said con- 521 US. Cl. ..355/13 83/203 83/210 circuit mates Paper feed device 83/36; 83/365 83/649 only when a predetermined amount of paper remains 5 int Cl 15/00 to be fed. The distance between the measuring point [58] mid a m:1::jjjjjjjjijjiiijii zalm 8% 156 of the phomansducer element and a Paper cutting device is greater then that between two pairs of feed rollers disposed in a section following said cutting device so that the feeding of undersized pieces of photocopy paper is prevented.

3 Claims, 2 Drawing Figures E a 1 i 1 E 4: DEVELOPING I DEVICE sub 43 2. .sxmsuasl U; l O: l I 7 1 8c e 2 i 1 I 3 15.1 L'. l L 23- 80 F1 8c 8b DEVICE FOR DETECTING THE END OF A ROLL OF COPY PAPER IN A PHOTOCOPYING MACHINE OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to a photocopy paper detecting device for use in copying machines or the like and, more particularly, to a device for measuring whether a predetermined length of copy paper remains in the machine.

The invention is usable in a copying machine of the type which utilizes a long roll of photocopying paper which is fed by a paper feed device (such as a pair of feed rollers) into a cutting device, where it is cut to a predetermined length and then fed into an exposure device. The photocopying paper, having been exposed, is then fed between two spaced apart pairs of feed rollers in a developing section. If a piece of photocopy paper having a length insufficient to bridge the gap between the two pairs of feed rollers is fed into the developing section in such a copying machine, the paper will be fed into the developing section by the first pair of rollers but will not be removed therefrom by the second pair. Instead it will jam in the copying machine developing section requiring the disassembly of the developing device in order to remove it. Such disassembly work may be complicated and cumbersome especially where the developing device is complicated in construction and contains a developing solution by which an operator may be contaminated. The under sized piece of copying paper mentioned above most often results when the end of a roll of copy paper is reached. In addition to the problem of jamming, the end of a roll of copy paper presents a further problem as the paper quality there is generally not suited for the copying operation, so that it is advantageous not to feed the paper at the end of a roll into the developing section.

In conventional copying machines of the type described, judgment of the operator is relied upon to prevent feeding of the trailing end of the roll of copy paper through the machine. If he does not stop the paper feed on time, the jamming mentioned above occurs. On the other hand, in order to avoid such jamming, the operator may replace the roll of photocopy paper before all the useable paper thereon is consumed, thus wasting photocopy paper.

Accordingly, one of the objects of the present invention is to provide a photocopy paper detecting device which automatically permits the use of a roll of photocopy paper until its last usable portion has been consumed, and then automatically rejects the unusable portion near the trailing end of the roll. The present invention thereby facilitates the copying operation, permits the maximum use of the usable photocopy paper on the roll, and prevents jamming of the tail end of the roll in the copying machine. More particularly, the object of the present invention is to provide a device for detecting whether a predetermined sufficient length of photocopy paper remains in storage or not.

SUMMARY OF THE INVENTION In accordance with the present invention, the photocopy paper leaving a storage roll is measured in order to determine whether a predetermined length thereof remains or not. Measurement is accomplished by a detection circuit in which a light source directs light upon the surface of the paper on the storage roll on which it is reflected into a phototransducer element. The intensity of the reflected light when paper is present on the roll is higher than when the roll is empty because the paper is more reflective than the empty roll. The relatively high intensity of the reflected light from the paper on the roll may increase the electromotive force of a phototransducer on which the light falls or may lower the resistance of a suitable transducer element so illuminated. Pending upon the intensity of the light so measured (and therefore upon the presence or absence of paper on the storage roll) a paper feed device control circuit is closed as to feed the paper or open so as to prevent the feed of the paper. Upon each advance of paper into the machine a predetermined length is cut off. When the leading edge of the cut paper reaches a normally-closed switch, said switch is opened thereby and, in turn, a power supply circuit for the control circuit is opened so that said control circuit is reset for the next paper feed operation.

In the device of the present invention, the distance from the point on the roll where the phototransducer measurement is made to a photocopy paper cutting station is greater than the distance between two spaced apart pairs of feed rollers disposed in a section, for example a developing section, which follows the cutting device of the copying machine.

According to one embodiment of the present invention, a normally-closed switch is situated in a light source circuit adapted to illuminate the photocopying paper, and when the photocopying paper has been found of sufficient length by the phototransducer element and the photocopying feed device control circuit, the normally-closed switch is opened so that the light source for illuminating the photocopying paper is turned off.

According to a further aspect of the present invention, a normally-closed switch which is adapted to be temporarily opened in synchronism with the advancement of the photocopying paper feed device is also utilized as a normally-closed switch which is adapted to reset the paper feed device control circuit whenever the feed of the paper is accomplished.

According to the present invention, the remaining photocopying paper is automatically, rapidly and positively measured whenever the feed of the paper is accomplished so that the copying operation efficiency may be remarkably improved without wasting the photocopying paper or causing the jamming of the paper in the copying machine. The detecting device of the present invention is simple in construction and has no mechanical elements which contact the photocopying paper (which paper is not required to be specially prepared for use with the present invention), so that longer service life may be ensured. The light source for illuminating the photocopying paper is turned off whenever the feed of the paper is accomplished as described above, so that said light source is only turned on intermittently for a very limited time. Thus, the premature exposure of the photocopying paper prior to the projection of an image thereupon for copying can be prevented, so that no pre-exposure preventive filter is utilized. Furthermore, the long service life of said light source is thus ensured.

The normally-closed switch used by the paper cutting device for determining the length of the paper to be cut off is also utilized as a normally-closed switch of the paper feed device control circuit as described above. Therefore, the improved design may be effected without increasing a number of components. Even where the predetermined length of photocopying paper is varied, the remaining photocopying paper, if it has a length less than a predetermined one, will be prevented from feeding into the machine, so that the arrangement in accordance with the present invention is more advantageous than the arrangement in which independent switches are provided.

The above and other objects, features and ad vantages of the present invention will become more apparent from the following description of one illustrative embodiment thereof with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic side view of an embodiment of the present invention; and

FIG. 2 is a circuit diagram thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, a roll of photocopying paper 1 is loosely carried by a supporting shaft 1a. The leading end of the roll of paper passes over a guide roller 2 and between a pair of feed rollers 3. The pair of feed rollers 3 comprises a roller 3a and a pressure roller 3b which coacts with the roller 3a during a feeding step. Normally roller 3b is spaced apart from roller 3a but during the feeding operation it is pressed against it by a solenoid 3d when a feed switch 3c is closed from the exterior (See FIG. 2 During feeding, the roller 3a is driven soas to advance the photocopying paper. Any other suitable feed means may be employed instead of the above feed rollers 3.

The leading end of the photocopying paper 1 is advanced by the pair of feed rollers 3 toward a cutter device 4, a charger 5, and an exposure device 6. The cutter device 4 is comprised of a fixed cutter blade 4a and a movable cutter blade 4b which coacts with the fixed cutter blade 4a for cutting off a predetermined length of photocopying paper. The movable cutter blade 4b is normally spaced away from the path of the photocopying paper. A normally-closed switch 7 is disposed adjacent to the end of the photocopying paper path within the exposure device 6 for determining the size of the photocopying paper to be cut off. An actuating member 7a of the switch 7 is caused to move by the leading end of the photocopying paper which thereby opens switch 7. The switch 7 is electrically connected to the solenoid 4c of the cutter device 4 so that the movable cutter blade 4b is caused to coact with the fixed cutter blade 4a when the normally-closed switch 7 is opened, thereby cutting off the photocopying paper into a predetermined size. Since, as will be explained below, the opening of switch 7 also stops feeding by the feed rollers 3, it may be seen that paper feed comes to a halt at the same time that the cutter device 4 severs a desired length of paper from the roll. It will be understood that any other suitable cutter device may be employed. The piece of photocopying paper out into a predetermined size in the manner described above is fed into the exposure device 6 by means of a suitable conveyor means or the like (not shown) and after exposure the photocopying paper is further fed into a developing device 8, in which the exposed photocopying paper is advanced through the passage P, defined by a pair of upper and lower guide members 8c by two pairs of

feed rollers

8a and 8b disposed on both ends of the guide members respectively, and is then developed in a manner well known in the art. The rolled photocopying paper 1 is consumed gradually as the photocopying process is cycled in the manner as described above. The rolled photocopying paper 1 is illuminated by the light from a light source 9 and the reflected light is detected by a phototransducer element 10 such as a photoconductive element. The distance 1 of the passage P,, from the point of reflection A to the cutter device 4 is made longer than the length L, of the passage P between, for example, the two pairs of

feed rollers

8a and 8b. The light source 9 and the photoconductive element 10 may be disposed at any position between rolled photocopying paper 1 and the pair of feed rollers 3 as long as the above distance requirement is satisfied.

The quantity of the reflected light incident upon the photoconductive element 10 depends upon the presence or absence of rolled photocopying paper 1. The output of the photoconductive element 10 varies accordingly. In accordance with the present invention, the variation in the output of the photoconductive ele ment 10 is detected by a feed control circuit which will be described in more detail below. The feed control circuit controls the pair of feed rollers 3 so that only when the light from light source 9 is reflected from photocopying paper at point A will the rollers advance the photocopying paper into the various processing devices described above. Therefore, when the rolled photocopying paper 1 is almost completely used up, so that a length thereof I less than 1, is in the passage P, with its leading end in the cutter device 4, there is no photocopying paper at the point A so that the feed device 3 is not actuated and no photocopying paper is fed. Operation of the device may be aided by providing a hub for the rolled photocopying paper of a black color to increase the variation in reflected light when the last of the photocopying paper leaves the hub.

Next the feed device control circuit of the present invention will be described. In addition to falling upon the photocopy paper at point A, light from the light source 9 also passes through a filter 11 which is adapted to dim it and falls upon a fixed photoconductive element 12. The photoconductive element 12 serves to compensate or correct for variations in the resistance of the photoconductive element 10 which may be caused by temperature variations. As may be seen in FIG. 2, the copying machine is provided with a main switch 13; a normally-open switch 14 in a power supply circuit for the feed device 3; and a transformer 15 whose primary is connected to switch 13 through a normally-closed switch 7. A paper feed switch 3c connects the solenoid 3d with the normally-open switch 14. Thus, the normally-open switch 14, paper feed switch 30 and the solenoid 3d are connected in parallel with the switch 7, and the primary of the transformer 15 together with the circuit containing the solenoid 3d are connected to the main switch 13.

The secondary of the transformer is connected to a paper feed device control circuit which includes a circuit for the light source 9 and a circuit for the photoconductive elements 10 and 12. A low voltage DC power supply circuit is comprised of the secondary of the transformer 15, a diode 16, a capacitor 17, a resistor l8 and a Zener diode 19. To this low voltage DC power supply circuit are connected in series the photoconductive elements 10 and 12 and transistors 21 and 22 which are coupled through a Zener diode with each other as shown. The relay 23 for actuating the normally-open switch 14 is controlled by the transistors 21 and 22. Reference numeral 24 designates a self-holding normally-open switch for the relay 23 and reference numeral designates a normally-closed switch operated by the relay 23. The normally-closed switch 25 is connected to the light source 9. As a variation, the normally-closed switch 7 may be connected in the power supply circuit for the relay 23 on the secondary side of the transformer 15.

The operation of the paper feed device control circuit is as follows. When the power switch 13 is first closed DC current is supplied to the photoconductive elements 10 and 12 through the normally-closed switch 7, the transformer 15, the diode 16, the capacitor 17, the resistor 18, and the Zener diode 19. At the same time the light source 9 is turned on. When the light from the light source 9 is reflected at the point A by the photocopy paper 1, the intensity of light incident upon the photoconductive element 10 is stronger so that the resistance of the photoconductive element 10 is much less than that of the photoconductive element 12. Thus,

because of the voltage division, the base voltage of the transistor 21 is higher than the Zener voltage of the Zener diode 20 so that both of the transistors 21 and 22 are driven into the conductive state. Current through these transistors activates the relay 23 so that the normally-open switch 24 is closed, and the relay 23 becomes self-holding. Simultaneously, the normallyclosed switch 25 is opened so that the light source 9 is turned off and the normally-open contact 14 is closed, so that the paper feed device 3 is actuated.

When there is no photocopying paper 1 at the point A, that is, when the remaining photocopying paper 1 is less than a predetermined length, the hub of the roll of photocopying paper is illuminated by the light from the light source 9 so that the reflected light is incident upon the photoconductive element 10. But in this case, the intensity of the reflective light is so weak that the resistance of the photoconductive element 10 becomes higher than that of the photoconductive element 12. As a result, the base voltage of the transistor 21 becomes lower than that across the Zener diode 20, so that neither of the transistors 21 and 22 are conductive. Therefore, the relay 23 is not actuated and the normally-open switch 14 is opened so that even when the paper feed switch 3c is depressed, the paper feed device 3 is not actuated at all. The normally-closed switch 7 for the cutter device 4 is temporarily opened whenever the leading edge of the photocopying paper reaches the switch 7 as described above, but as soon as the photocopying paper has left the switch 7, it is closed again so that the paper feed device control circuit is also closed. According to the present invention, whenever the paper is fed, a measurement is made of the remaining photocopying paper to determine whether it is of a sufficient length to be cut off into a predetermined size. This can also be done when the main switch 13 is closed when the copying machine is started.

When the main switch 13 is closed, current flows through normally-closed switch 7 and the primary of the transformer 15. Current also flows through the secondary circuit through light source 9 and the normally-closed switch 25, causing the light source to illuminate point A. If photocopying paper is present at point A, transistors 21 and 22 conduct current from the secondary of the transformer 15 through the relay 23. Activation of relay 23 in this manner closes the normally-open switch 24 and renders the relay self-holding by establishing an alternate current path for current flowing through the relay. Activation of relay 23 opens the normally-closed switch 25 and darkens light source 9. Simultaneously, relay 23 closes normally-open switch 14. When feed switch 30 is closed under these conditions, solenoid 3d moves the pair of feed rollers 3 toward each other and initiates the advance of photocopying paper through the machine. This advance continues until the leading edge of the paper opens normally-closed switch 7. Opening of switch 7 causes the solenoid 4c of the cutter device 4 to operate the cutter device to cut the photocopy paper. The opening of switch 7 also breaks the current flow to the solenoid 23 and results in the opening of the normallyopen switch 14, thus deenergizing the paper feed solenoid 3d and halting the advance of photocopy paper from the roll 1. When the severed segment of the photocopying paper has been advanced fully through the charger exposure area and into the developing device, switch 7 can again close and initiate the next copying cycle by causing the feed device control circuit to again ascertain whether or not photocopying paper remains on the roll 1.

The present invention have been so far described with particular reference to one illustrative embodiment thereof, but it will be understood that variations and modifications can be effected without departing from the true spirit of the present invention as described above and as defined in the following claims.

Iclaim:

1. A photocopying paper detecting device for use with copying machines having a passage for the feeding of photocopying paper comprising photocopying paper supply means including a first point area located thereon from which the paper is led therefrom;

drive means for feeding said paper along a feed path for said driven paper having a plurality of stations therealong comprising in sequence:

a cutter station,

a charger station,

an exposure station, and

a developing station;

said cutter station defining a second point area along said feed path;

said developing station having third and fourth point areas located therein along said feed path defining a first predetermined length within which the paper is developed;

said cutter station second point area spaced from said first point area so that a second predetermined length exists therebetween that is greater than said first predetermined area;

detecting means located adjacent said first point area, said detecting means including a light source for detecting the presence of paper at said first point area and thereby generating an electrical signal;

electrical circuit means for said drive means including a first normally-closed switch located between said exposure station and said developing station, said normally-closed switch opened by the passage of a leading end of paper previously cut at said cutter station whereby the feed is temporarily interrupted for cutting the paper at said cutter station;

said circuit means further including:

a first normally-open switch that prevents actuation of said drive means in its open position,

a second normally-open switch that is closed by application of said electrical signal thereby closing said first normally-open switch to actuate said drive means; and

a second normally-closed switch connected in circuit relationship with said light source, said second normally-closed switch being opened when said second normally-open switch closes to thereby de-actuate said light source.

2. A photocopying paper detecting device according to claim 1 in which said circuit means includes activatable means that is electrically conductive when the paper is present at said first point area, and non-conductive when the paper is not present at said first point area, and said circuit means further includes an electrical relay that is actuated when said activatable means is conductive to cause closing of both said first and second normally-open switches and opening of said second normally-closed switch, said relay becoming self-holding when conductive.

3. A photocopying paper detecting device according to claim 1 in which said third and fourth point areas are defined by spaced roller means located within said developing station, and the paper positioned between said roller means having a length at least as long as said second predetermined distance.

Claims

1. A photocopying paper detecting device for use with copying machines having a passage for the feeding of photocopying paper comprising photocopying paper supply means including a first point area located thereon from which the paper is led therefrom; drive means for feeding said paper along a feed path for said driven paper having a plurality of stations therealong comprising in sequence: a cutter station, a charger station, an exposure station, and a developing station; said cutter station defining a second point area along said feed path; said developing station having third and fourth point areas located therein along said feed path defining a first predetermined length within which the paper is developed; said cutter station second point area spaced from said first point area so that a second predetermined length exists therebetween that is greater than said first predetermined area; detecting means located adjacent said first point area, said detecting means including a light source for detecting the presence of paper at said first point area and thereby generating an electrical signal; electrical circuit means for said drive means including a first normally-closed switch located between said exposure station and said developing station, said normally-closed switch opened by the passage of a leading end of paper previously cut at said cutter station whereby the feed is temporarily interrupted for cutting the paper at said cutter station; said circuit means further including: a first normally-open switch that prevents actuation of said drive means in its open position, a second normally-open switch that is closed by application of said electrical signal thereby closing said first normallyopen switch to actuate said drive means; and a second normally-closed switch connected in circuit relationship with said light source, said second normallyclosed switch being opened when said second normally-open switch closes to thereby de-actuate said light source.