EP0505272A1

EP0505272A1 - Paper feeding apparatus for color video printer

Info

Publication number: EP0505272A1
Application number: EP92400723A
Authority: EP
Inventors: Byung Mu Huh; Sung Joo Lee
Original assignee: Gold Star Co Ltd
Current assignee: LG Electronics Inc
Priority date: 1991-03-21
Filing date: 1992-03-18
Publication date: 1992-09-23
Also published as: JPH0597280A

Abstract

A paper feeding apparatus of a color video printer which reliably prevents an abnormal feeding of a receiver paper 2 such as double feeding. The apparatus includes a paper thickness sensing member 220 for sensing a thickness of the receiver paper which is fed from a paper cartridge 91 so as to determine whether the receiver paper is normally fed and output a control signal corresponding to the determination, a paper jam control member 700 for preventing the receiver paper from being jammed at developing rollers 41,42, and a control member 500 for controlling the paper feeder to provide a reversed tension for the receiver paper in accordance with control signals outputted from the paper thickness sensing member and the paper jam control member. The present invention provides a paper feeder of a color video printer which provides a good quality of color image, prevents a crumple of the receiver paper, and prevents the developing rollers from being damaged due to a paper jam.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to color video printers such as cycolor type printers, and more particularly to a paper feed¡ng apparatus for use in color video printers which is capable of efficiently preventing a paper jam, thereby obtaining a picture of high quality and also preventing crumple of the receiver paper and sudden damage of a developing roller driving motor.

2. Description of the Prior Art

With reference to FIG. 1 which shows a construction of a conventional cycolor type color video printer, the printer generally comprises a film supply reel 10 for supplying a cycolor film 1, a film feed roller 20 for drawing out the cycolor film 1 from the film supply reel 10 in order to feed the film 1, an exposing unit 3, such as a F/O CRT (fiber optics cathode ray tube), for exposing the cycolor film 1 to a light, having been passed by the feed roller 10, to the light in accordance with an image signal corresponding to the desired printing image, upper and lower capstan rollers 30 (31 and 32) for controlling the feeding of the cycolor film 1 which has been exposed by the exposing unit 3, and a paper cartridge 91 for allowing receiver papers 2, on each of which the desired color image is to be printed, to be stacked therein. In addition, a paper feed roller 80 and a paper feed base 92 are provided adjacent to the paper cartridge 91, the one is adapted to feed each receiver paper 2 from the paper cartridge 91 to a film running loop of the cycolor film 1 and the other to guide the receiver paper 2, having been fed by the paper feed roller 80, to the film running loop. A pair of developing rollers 40 (41 and 42) are disposed at a front of the capstan rollers 30 so as to be spaced therefrom. The developing rollers 40 form a nip therebetween through which the cycolor film 1 and the individual receiver paper 2 are introduced at the same time in order to make the desired color image of the cycolor film 1 to be decaled onto the receiver paper 2.
The color video printer is additionally provided with a film take-up reel 50 on which the cycolor film 1 having discharged from the developing rollers 40 is rewound, a heat-fixing unit 60 which comprises a press roller 61 and a heat cover roller 62, and is adapted to heat the receiver paper 2, which has been separated from the cycolor film 1 simultaneously with being discharged from the developing rollers 40 and has the desired color image decaled thereon, in order to fix the color image on the paper 2.
As shown in the drawing, a plurality of guide rollers 71, 72 and 73 are disposed at the film running loop between the film supply reel 10 and the film take-up reel 50 so as to guide the running of the cycolor film 1.
Hereinafter, the operation of the conventional cycolor type color video printer having the above construction will be described as follows.
The cycolor film 1 is drawn out of the film supply reel 10 by an operator, and passes through the film running loop, then last taken up the front edge of the cycolor film 1 by the take-up reel 50, thereby forming a running loop. Thereafter, the receiver papers 2 are stacked in the paper cartridge 91 so as to accomplish the printing standby.
Upon accomplishing the printing standby, the control key (not shown) of the color video printer is pressed by the operator in order to drive the printer. In result, the cycolor film 1 is gradually drawn out of the film supply reel 10 at a predetermined feeding velocity by means of the film feed roller 20, and passes through the exposing unit 3, the capstan rollers 30, the developing rollers 40, sequentially, then taken up by the take-up reel 50. At this time upon running through the running loop of the cycolor film 1 between the film supply reel 10 and the film take-up reel 50, the cycolor film 1 is guided by the guide rollers 71, 72 and 73 disposed at the respective positions, and controlled by the capstan rollers 30 in order to maintain predetermined tension and feeding velocity thereof.
On the other hand, the exposing unit 3 converts an electric image signal corresponding to a color image which is to be printed into an optical image signal, then exposes the cycolor film 1 to the light in accordance with the optical image signal, thereby making a desired printing image on the cycolor film 1. Thereafter, prior to passing through the nip formed between the upper and lower developing rollers 41 and 42, the exposed cycolor film 1 having the desired printing image thereon passes through the guide roller 72 and the capstan rollers 30, sequentially. At the same time, the paper feed roller 80 draws out the receiver paper 2 of the paper cartridge 91 in order to feed to the running loop of the cycolor film 1 by guidance of the paper feed base 92, thereby making the receiver paper 2 to pass through the nip of the developing rollers 40 under the condition that the receiver paper 2 passes as being closely disposed under the cycolor film 1 at the same time. In accordance, the upper and lower developing rollers 41 and 42 provide a predetermined pressure for the cycolor film 1 and the receiver paper 2 so as to compress them, thereby developing the desired printing image of the cycolor film 1 to be decaled onto the receiver paper 2 by virtue of the pressure.
Just after passing through the developing rollers 40, the cycolor film 1 and the receiver paper 2 are stuck to each other, thus they have to be generally separated from each other by means of an additional separating member (not shown), thereafter, the one is taken up by the take-up reel 50 and the other is fed to the heat-fixing unit 60 in order to cause the developed color image on the receiver paper 2 to be fixed by the press roller 61 and the heat cover roller 62.
Additionally, the developing operation which is performed by the developing rollers 40 will be described in detail as follows.
Referring to FIG. 2 which shows a schematic profile of the developing rollers 40 of the conventional printer, each roller 41, 42 has flanges 41a and 41b, 42a and 42b at both ends thereof so that when the rollers 41 and 42 are compressed with each other, there is provided a nip, that is, a predetermined gap t, between the rollers 41 and 42 by virtue of the flanges 41a, 41b, 42a, and 42. Here, the developing rollers 41 and 42 are constructed such that the gap t between them is conventionally sized so as to be slightly larger than a thickness t₁ of the cycolor film 1 (see FIG. 3A) and also smaller than a thickness t₂ of the receiver paper 2 (see FIG. 3B). Hence, if the cycolor film 1 having the smaller thickness t₁ than the gap t passes alone through the gap t, it will be smoothly transferred. However, if the cycolor film 1 passes through the gap t between the rollers 41 and 42 together with the receiver paper 2 having the larger thickness t₂ than the gap t, resulting in the total thickness substantially larger than the gap, that is, t₁ + t₂ > t, there is provided a substantially higher pressure between the developing rollers 41 and 42. In result, as the cycolor film 1 passes through the gap t between the develop¡ ng rollers 41 and 42, a great number of cylith capsules (not shown), which are applied on the cycolor film 1 and have an unusual sensibllity for R, G and B color lights, respectively, are broken due to the pressure provided between the rollers 41 and 42 so that the desired color image of the cycolor film 1 is decaled onto the receiver paper 2 so as to be developed.
At this time, the pressure provided between the developing rollers. 41 and 42 has a close relationship with rupture of the cylith capsules of the cycolor film 1, thus the pressure is known as an important factor for performing a smooth printing operation. In addition, the pressure level is influenced by the gap t between the developing rollers 41 and 42.
That is, as the value of t₁ + t₂ is always constant, the pressure level of the developing rollers 41 and 42 is determined by varying the gap t.
In accordance, if the gap t between the developing rollers 41 and 42 can not be constantly maintained, the receiver paper 2 may be crumpled, resulting in distorting the image on the receiver paper 2, and also there may occur a paper ]am due to a double feeding of the receiver papers, such as resulting from a mis-operation in separating the individual receiver paper 2 from the paper stack of the paper cartridge 91.
However, the conventional cycolor type of color video printer is provided with no device for preventing the receiver papers 2 from being fed doubly, and also no mechanism for controlling the printing operation of the printer depending upon sensing the double feeding of the receiver papers 2. In result, if there occurs a double feeding of the receiver papers 2 such as due to the mis-operation in separation the individual receiver paper 2 from the paper stack, two or more receiver papers 2 will be introduced into the gap t between the developing rollers 41 and 42, resulting in increasing the value of t₁ + t₂ so as to be more than a predetermined reference value, and thus substantially increasing the pressure for the receiver papers 2. Hence, the color image on the receiver paper 2 undesirably changes due to the increasing pressure, thereby resulting in deteriorating the image quality, and also there occurs a crumple of the receiver paper 2 because the receiver paper 2 is subjected to a substantially higher pressure than the predetermined reference presure. In addition, if it is failed to separate the individual receiver paper 2 from the paper stack of the paper cartridge 91, resulting in the double feeding of the receiver papers 2, there occurs the paper jam in which the receiver papers 2 can not be drawn out of the gap t between the developing rollers 41 and 42 which can not rotate, thus the driving motor for driving the developing rollers 41 and 42 is subjected to an overload, thereby causing the driving motor to be damaged.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a paper feeding apparatus for use in a cycolor type color video printer in which the above-mentioned problems can be overcome, and which can prevent a double feeding of receiver papers, thus prevent a paper jam, cause a good quality of color printing image to be obtained, and prevent a driving motor for driving upper and lower developing rollers from being subjected to an overload, thereby preventing a damage of the driving motor.
The above object of the present invention can be accomplished by providing a paper feeding apparatus for use in a color video printer comprising paper pressing means for pressing an individual receiver paper which is fed from a paper cartridge in order to cause the receiver paper to closely abut against a paper feed base; paper thickness sensing means for sensing a thickness of the receiver paper which is fed from a paper cartridge so as to determine whether the receiver paper is normally fed and output a control signal corresponding to the determination; a paper sensing member for sensing whether the receiver paper which has been fed from the paper cartridge passes through a nip between the developing rollers; a reversed-tension member for providing the reversed tension for the receiver paper which is passing through the nip between the developing rollers, the reversed-tension member being disposed on a paper feed base; and control means for controlling, in accordance with control signals outputted from the paper thickness sensing means and the paper jam control means, the paper feeder to forwardly feed the receiver paper and also provide a reversed tension for the receiver paper in case of normal feeding or feed the receiver paper in the reversed direction in case of occurrence of abnormal feeding.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view showing a construction of a known cycolor type color video printer;
FIG. 2 is a schematic front view of upper and lower developing rollers of the printer of FIG. 1;
FIGs. 3A and 3B are front views of a conventional cycolor film and a receiver paper, respectively;
FIG. 4 is a schematic view showing a construction of a cycolor type color video printer provided with an embodiment of a paper feeding apparatus according to the present invention which is capable of preventing a double feeding of receiver papers and also preventing a paper jam;
FIGs. 5 and 6 are schematic views of another embodiment of a paper feeding apparatus according to the present invention, respectively, in which:
FIG. 5 is a view corresponding to FIG. 4; and
FIG. 6 is a perspective view of a paper thickness sensing member of the paper feeder;
FIG. 7 is a view corresponding to FIG. 4, but showing still another embodiment of a paper feeding apparatus of the present invention;
FIG. 8 is an enlarged perspective view of a receiver paper sensing member according to the present invention; and
FIG. 9 is flow diagram illustrating the sequence of operation of jam routine of the paper feeding apparatus in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 4 which shows a paper feeding apparatus of a cycolor type of color video printer according to this invention which is capable of preventing a double feeding of receiver papers and preventing a paper jam, the apparatus comprises a paper pressing member 100 for pressing the individual receiver paper 2 having been drawn out of a paper cartridge 91 in order to make the paper 2 closely abut against a paper feed base 92, a sensing member 200 for sensing a thickness of the receiver paper 2 from the paper feed base 92 in order to output a control signal in case of sensing a paper misfeeding such as double feeding. A paper jam control member 700 is provided to prevent a paper jam in which the receiver paper 2 is jammed at upper and lower developing rollers 40 (41, 42), and a control member 500 is provided to control the paper feeder such that in accordance with control signals outputted from the sensing member 200 and the paper jam control member 700, respectively, it feeds the receiver paper 2, provides a reversed tension for the receiver paper 2 or reversely feeds the receiver paper 2 in case of occurrence of the misfeeding of the papers 2. In addition, the paper feeding apparatus of this invention is provided with an alarm member 600 for generating an alarm signal under the control of the control member 500 in case of misfeeding of the paper, thereby alarming the operator to the misfeeding of the paper 2.
Here, the paper jam control member 700 comprises a paper sensor 400 for sensing whether the receiver paper 2 which has been fed from the paper cartridge 91 by the paper feed roller 80 passes through a nip between the upper and lower developing rollers 41 and 42, and a pair of reversed-tension rollers 300 disposed at a front portion of the paper feed base 92 in order to provide the reversed tension for the receiver paper 2.
The paper pressing member 100 comprises a pressing plate 110 for providing a predetermined pressure for the receiver paper 2 on the paper feed base 92 so as to cause the receiver paper 2 to be guided without occurrence of a crumple at a front edge thereof, a compression coil spring 120 for biasing the pressing plate 110 and a hinge shaft 130 to which the rear end of the pressing plate 110 is rotatably mounted.
On the other hand, the sensing member 200 comprises a seesaw type lever 210 which is hinged at a center thereof to a hinge shaft 213 above the paper pressing member 100, and seesawed about the hinge shaft 213 depending upon the thickness of the receiver paper 2, a compression coil spring 230 which is connected at an end to the seesaw type lever 210 and at the other end to a mounting plate 240 spaced apart from and above the paper cartridge 91, thereby upwardly biasing the seesaw type lever 210, and a paper misfeeding signal generator 220 for generating a signal representing the sensed thickness of the receiver paper 2 according to a seesaw angle of the seesaw type lever 210.
The seesaw type lever 210 integrally comprises a paper contact part 212 and an interlocking part 214, both occupying opposite sides thereof on the basis of the hinge shaft 213 and having predetermined lengths, X and Y, respectively. Here, the length X of the paper contact part 212 is preferably formed to be shorter than the length Y of the interlocking part 214, thereby making the displacement of the paper contact part 212 to be less than that of the interlocking part 214.
The paper contact part 212 is provided at a free end thereof with a generally spherical protrusion 211 so as to efficiently prevent the individual receiver paper 2 from being scratched when the free end of the paper contact part 212 contacts the receiver paper 2.
On the other hand, the paper misfeeding signal generator 220 comprises a movable piece 221 which is rotatably mounted to a shaft pin 225 above the mounting plate 240 and is provided at a front end thereof with a movable contact 222. A stationary contact 223 is fixed on the mounting plate 240 so as to be spaced apart from the movable contact 222 by a predetermined gap. In addition, there is provided a coil spring 224 disposed between the movable piece 221 and the mounting plate 240 so as to upwardly bias the movable piece 221.
In addition, as shown in FIGs. 5 and 6 the paper misfeeding signal generator 220 may comprise a light intercepting piece 250 axially secured to a rear end of the seesaw type lever 210 and movably disposed between light emitting and light receiving elements 251 and 252 which are vertically disposed on the mounting plate 240 so as to be spaced apart from each other by a predetermined distance. In result, the light emitting and light receiving elements 251 and 252 can sense a displacement of the light intercepting piece 250 which selectively intercepts the light from the light emitting element 251 in accordance with the thickness of the receiver paper 2.
Described in detail, the light receiving elements 252 are vertically arranged at predetermined uniform intervals as shown in FIG. 6. Therefore, if the thickness of the receiver paper 2 is 0.12 mm, and the length X (the distance between the hinge shaft 213 and the paper contact part 212) is 5 mm, and also the length Y (the distance between the hinge shaft 213 and the light intercepting piece 250) is 50 mm, the displacement ratio of the paper contact part 212 and the light intercepting piece 250 with respect to the thickness of the receiver paper 2 is calculated as 1:10, thus the displacement of the rear end of the light intercepting piece 250 will be about 1.2 mm. In result, it is preferable to select about 1 mm of the arrangement intervals of the light receiving elements 252.
As described in FIG. 7 which depicts another embodiment of the sensing member 200, the sensing member 200 may comprise a piezo-electric element 260 which is able to generate different voltages in accordance with the thickness of the receiver paper 2. The piezo-electric element 260 is mounted on the paper feed base 92 so as to be spaced apart therefrom at a predetermined distance.
Turning again to FIG. 4, the reversed-tension roller 300 comprises upper and lower rollers providing a nip therebetween and introducing the individual receiver paper 2 to the nip, thereby providing forward/reversed tension for the individual receiver paper 2. On the other hand, as shown in FIG. 5 the reversed-tension roller 300 may comprise one roller such that it is rotatably and resiliently contacted with the upper surface of the paper feed base 92 under a predetermined pressure provided by a compression coil spring 310.
The control member 500 comprises a paper feed motor 530 for driving the paper feed roller 80 and the reversed-tension roller 300 to rotate in forward or reversed direction, a microcomputer 510 for controlling the forward feeding, the reversed tension and the reversed feeding of the receiver paper 2 in accordance with control signals outputted from the sensing member 200, the paper misfeeding signal generating member 220 and the paper sensing member 400. In addition, there are provided a paper feed motor driving part 520 and a rotating power transmission 540 which are operated under the control of the microcomputer 510, the one adapted to drive the paper feed motor 530 and the other adapted to cut off the rotating power which is to be transmitted from the paper feed motor 530 to the paper feed roller 80, when it is necessary to apply the reversed tension to the receiver paper 2.
In the drawings, the same elements as those of the prior art are denoted as the same reference numbers as those of the prior art, and the description of the same elements will be omitted for the simplicity.
The operational effect of and embodiment of the paper feeding apparatus of the cycolor type color video printer of this invention having the above construction will be described in detail as follows.
With reference to FIG. 4, when a paper feed signal is applied from a main control part of the color video printer to a servo control part of the printer, that is, the microcomputer 510 of the control member 500 when the cycolor film 1 runs across the conventional film running loop, the paper feed motor driving part 520 drives the paper feed motor 530 under the control of the microcomputer 510 in order to rotate the motor 530 in the forward direction. In result, the paper feed roller 80 and the reversed-tension rollers 300 rotate in forward direction, respectively, thereby causing the individual receiver paper 2 in the paper cartridge 91 to be fed to the film running loop under the guidance of the paper feed base 92.
At this time, as the front edge of the receiver paper 2 passes through the paper pressing plate 110 which is biased by the coil spring 120, the receiver paper 2 can be guided to the film running loop without occurrence of crumple. Sequentially, the front edge of the receiver paper 2 upwardly pushes the spherical protrusion 211 of the seesaw type lever 210 as it passes under the protrusion 211, thereby causing the seesaw type lever 210 to clockwise seesaw about the hinge shaft 213.
Here, if the receiver paper 2 passing under the protrusion 211 has the predetermined normal thickness, that is, if one receiver paper 2 passes under the protrusion 211, the interlocking part 214 of the seesaw type lever 210 is downwardly displaced due to the seesaw movement of the lever 210, however, the downward displacement of the interlocking part 214 is not sufficient to make the movable contact 222 of the movable piece 221 contact with the stationary contact 223. In result, the microcomputer 410 determines that the present paper feeding condition is normal condition, thus controls the paper feeder to continue the paper feeding. Thereafter, upon accomplishing the desired paper feeding the seesaw type lever 210 returns to the original position by counterclockwise seesawing thereof about the hinge shaft 213 owing to the restoring force of the coil spring 230.
At this time, the reversed-tension rollers 300 provide a predetermined pressure for the receiver paper 2 by virtue of the coil spring 310, thereby allowing the receiver paper 2 to smoothly advance under the condition of contact with the paper feed base 92. In addition, the seesaw type lever 210 is provided at the front end thereof with the spherical protrusion 211 as described above, thereby efficiently preventing the receiver paper 2 from being scratched.
However, if the receiver paper 2 passing under the protrusion 211 has a thickness which is larger than the predetermined normal thickness, that is, if two or more receiver papers 2 pass simultaneously under the protrusion 211, the seesaw amount of the lever 210 substantially increases so that the downward displacement of the interlocking part 214 is sufficient to downwardly bias the movable piece 221 until the movable contact 222 of the movable piece 221 contacts with the stationary contact 223, thereby causing the microcomputer 510 is applied with a control signal representing occurrence of paper misfeeding. In result, the microcomputer 510 determines that the present paper feeding condition is abnormal condition, thus controls the paper feed motor 530 by way of the paper feed motor driving part 520 so as to rotate in the reversed direction. In accordance with the reversed rotation of the paper feed motor 530, the reversed-tension roller 300 and the paper feed roller 80 rotate in reversed direction, respectively, thereby causing the two or more receiver papers 2 on the paper feed base 92 to be fed in the reversed direction in order to return to the paper stack of the paper cartridge 91. Here, the microcomputer 510 drives the paper feed roller 80 and the reversed-tension roller 300 to rotate in the reversed direction for a predetermined time so that when the receiver papers 2 completely return to the original position in the paper cartridge 91, the paper feed roller 80 and the reversed-tension roller 300 reliably stop rotating in the reversed direction.
In addition, upon sensing a misfeeding of the receiver paper 2, the microcomputer 510 controls the alarm member 600 to alarm the operator to the misfeeding of the receiver paper 2. Here, the alarm member 600 may use a light emitting diode (LED) alone for displaying the paper misfeeding, a buzzer alone for generating a voice signal for the paper misfeeding or a combination of the LED and the buzzer.
On the other hand, when there is no control signal from the sensing member 200, thus it is determined that the individual receiver paper 2 is fed normally, the microcomputer 510 continuously scans the control signals outputted from the paper sensor 400 in order to drive the reversed-tension roller 300 to rotate in the reversed direction when the front edge of the receiver paper 2 initially passes through the developing rollers 40, thereby providing a predetermined reversed tension for the receiver paper 2 so as to cause the receiver paper 2 to advance without occurrence of crumple.
Thereafter, as the receiver paper 2 passes through a nip between the upper and lower developing rollers 40 (41 and 42) under the condition of being applied with the predetermined reversed tension, the desired color image on the cycolor film 1 is printed onto the receiver paper 2. Sequentially, the receiver paper 2 having the color image thereon is heated by a heat-fixing unit 60 so as to fix the color image.
FIG. 9 is a flow diagram illustrating the sequence of operation of jam routine of the paper feeding apparatus of the present invention. As described in the diagram, when the receiver paper 2 in the paper cartridge 91 is fed by the paper feed roller 80 and is initially caught by the upper and lower developing rollers 41 and 42 after predetermined revolutions of the paper feed roller 80 or lapse of a predetermined time, the microcomputer 510 of the control member 500 controls the rotating velocity or the rotating direction of the paper feed motor 53. That is, the microcomputer 510 controls the reversed-tension roller 300 to make a rotating linear velocity V1 of the roller 300 be less than a rotating linear velocity V2 of the developing rollers 41 and 42 or make the rotating direction of the roller 300 to be reversed, thereby causing the receiver paper 2 to be applied with the predetermined reversed tension.
Here, in order to determine the time when the receiver paper 2 is applied with the reversed tension, there is provided the paper sensor 400, shown in FIG. 8, at a front end of the paper discharging part of the developing rollers 41 and 42. Conventionally, the cycolor film 1 is constructed to have a narrower width than that of the receiver paper 2 by a predetermined width so that by scanning the periphery of the receiver paper 2 which does not overlap with the cycolor film 1 such as by using an optical sensor, the paper sensor 400 can easily determine whether the receiver paper 2 is discharged from the develop¡ng rollers 41 and 42.
Also as described above, the reversed-tension roller 300 is installed on the paper feed base 92 so as to contact with the receiver paper 2, and comprises one or two rollers. At this time, in case of a reversed-tension roller 300 comprising one roller as shown in FIG. 5, the roller 300 is installed with respect to the paper feed base 92 such that the receiver paper 2 is applied with the reversed tension resulting from a contact frictional force generated between the reversed-tension roller 300 and the paper feed base 92. However, in case of a reversed-tension roller 300 comprising two rollers as shown in FIG. 4, the receiver paper 2 is applied with the reversed tension resulting from a contact frictional force generated between the two rollers 300.
On the other hand, when it is intended to apply the reversed tension to the receiver paper 2, the rotating power transmission 540 temporarily stops transmitting the rotating power from the paper feed motor 530 to the paper feed roller 80 under the control of the microcomputer 510, resulting in temporarily stopping the paper feed motor 80, thereby stopping a next feeding of the receiver paper 2. In result, it is possible to prevent another double feeding of the receiver paper 2.
With reference to FIGs. 5 and 6, there is shown another embodiment of the paper feeding apparatus of cycolor type color video printer of this invention. This embodiment of the paper feeder is constructed to have the same construction as that of the above first embodiment except for the paper misfeeding signal generator 220 for generating the paper misfeeding signal by sensing a thickness of the receiver paper 2 according to a seesaw angle of the seesaw type lever 210, thus only thy operational effect of the characteristic construction of the another embodiment will be described as follows.
As shown in the drawings, when one receiver paper 2 is normally fed by the paper feeder of this invention in order to pass under the paper contact part 212 of the seesaw type lever 210, the paper contact part 212 moves upwardly just as much as the thickness of the receiver paper 2, thereby causing the light intercepting piece 250 of the lever 210 to move downwardly just as much as the upward displacement of the paper contact part 212. At this time, each light emitting element 251 emits light to the corresponding light receiving element 252, thus the light intercepting piece 250 intercepts a light emitted from a light emitting element 251 which is disposed at the same position as that of the light intercepting piece 250, thereby causing a light receiving element 252 corresponding to the light emitting element 251 to receive no light.
At this time in case of normal feeding of the receiver paper 2, the light intercepting piece 250 will be disposed at a position corresponding to the first and second light receiving elements 252 because the thickness of each receiver paper 2 is conventionally 0.12 mm, thereby intercepting the light which is intended to be received by the first and second light receiving elements 252. In result, the light receiving elements 252 output light receiving data, representing that the first and second light receiving elements 252 do not receive light, to the microcomputer 510. Therefore, the microcomputer 510 controls the paper feed motor driving part 520 to cause the paper feed roller 80 and the reversed-tension roller 300 to continuously rotate without change of the rotating direction.
However, when there occurs a misfeeding of the receiver paper 2 due to feeding of two or more receiver papers 2 simultaneously, the downward displacement of the light intercepting piece 250 increases so as to cause the piece 250 to be disposed at least at a position corresponding to the third and fourth light receiving elements 252. In result, the microcomputer 510 is applied with light receiving data, representing that the corresponding light receiving elements 252 do not receive light, from the light receiving elements 252, thus determines that there occurs a misfeeding of the receiving paper 2, then controls the paper feed motor driving part 520 to cause the paper feed roller 80 and the reversed-tension roller 300 to rotate in the reversed direction, respectively. In accordance, the receiver papers 2 return to the paper cartridge 91. At this time, the microcomputer 510 controls the alarm member 600 so as to alarm the operator to the occurrence of misfeeding by using an alarm signal or a LED display.
FIG. 7 shows a second embodiment of the paper feeding apparatus of the cycolor type color video printer of this invention. The operational effect of the second embodiment will be described as follows.
As shown in FIG. 7, the piezo-electric element 260 detects the thickness of the receiver paper 2, and generates a voltage in accordance with the thickness of the receiver paper 2, then outputs the voltage to the microcomputer 510. Upon receiving the voltage from the piezoelectric element 260, the microcomputer 510 compares the voltage of the element 260 with a reference voltage stored therein in order to determine whether the present paper feeding operation is normal.
In other words, in case of normal feeding of one receiver paper 2, the piezo-electric element 260 is applied with a pressure corresponding to the thickness of the receiver paper 2, thereby generating a voltage corresponding to the pressure which is less than the reference voltage. Hence, the microcomputer 510 determines that the present paper feeding operation is normal.
However, when there occurs a misfeeding of the receiver paper 2 due to feeding of two or more receiver papers 2 at the same time, the piezoelectric element 260 is applied with a higher pressure due to the increase of the thickness of the receiver papers 2 such that it generates a voltage higher than the reference voltage. Hence, the microcomputer 510 determines that two or more receiver papers 2 are fed at the same time, and controls the paper feed motor driving part 520 to cause the paper feed roller 80 and the reversed-tension roller 300 to rotate in the reversed direction, respectively, thereby causing the receiver papers 2 to return to the paper cartridge 91. At this time, the microcomputer 510 also controls the alarm member 600 so as to alarm the operator to the'occurrence of misfeeding by using an alarm signal or a LED display.
As described above, the present Invention provides a paper feeding apparatus of a cycolor type color video printer which reliably prevents a receiver paper misfeeding such as double feeding, thereby providing a good quality of color image, preventing crumple of the receiver paper, and preventing developing rollers from being damaged due to a paper jam.
In addition, besides being applied to the cycolor type color video printer as described above, the present invention is preferably applied to several types of information machinery, such as duplicators, in which individual printing papers have to be automatically fed by an automatic paper feeder.
Although the preferred embodiments of the present invent¡on have been disclosed for illustrative purpose, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

A paper feeding apparatus of a color video printer comprising:
paper thickness sensing means for sensing a thickness of a receiver paper which is fed from a paper cartridge so as to determine whether the receiver paper is normally fed and output a control signal corresponding to the determination;
paper jam control means for preventing said receiver paper from being jammed at developing rollers; and
control means for controlling said paper feeding apparatus to provide a reversed tension for said receiver paper in accordance with control signals outputted from said paper thickness sensing means and said paper jam control means.
The apparatus according to Claim 1, wherein said apparatus further comprises an alarm means for alarming the operator to the abnormal feeding of the receiver paper under the control of the control means.
The apparatus according to Claim 1, wherein said apparatus further comprises paper pressing means for pressing the receiver paper which is fed from paper cartridge, thereby causing the receiver paper to closely contact with a paper feed base.
The apparatus according to Claim 3, wherein said paper pressing means comprises:
pressing plate means for providing a predetermined pressure for the receiver paper on the paper feed base, thereby causing the receiver paper to be guided without occurrence of crumple at a front edge thereof;
biasing means for biasing said pressing plate means; and
pivot means for allowing said pressing plate means to be rotatably mounted thereto.
The apparatus according to Claim 1, wherein said paper thickness sensing means comprises:
a seesaw type lever hinged to a predetermined position in order to change a seesaw angle thereof in accordance with the thickness of the receiver paper;
biasing means for upwardly biasing said seesaw type lever, said biasing means being mounted on a mounting plate which is disposed at a predetermined position; and
paper misfeeding signal generating means for generating a signal representing a sensed thickness of the receiver paper according to the seesaw angle of the seesaw type lever.
The apparatus according to Claim 5, wherein said seesaw type lever comprises:
a paper contact part formed as extending from a hinge shaft which is provided as a seesaw center toward the paper feed base by a predetermined length;
an interlocking part formed as extending from the hinge shaft in an opposite direction to said paper contact part by a predetermined length which is longer than that of the paper contact part; and
a spherical protrusion for preventing the receiver paper from being scratched when a free end of the paper contact part contacts with the receiver paper, said spherical protrusion being provided at a front end of the paper contact part.
The apparatus according to Claim 5, wherein said paper misfeeding signal generating means comprises:
a movable piece which is rotatably mounted to a shaft pin on said mounting plate and is provided with a movable contact;
a stationary contact which is mounted on the mounting plate in order to face with said movable contact with a predetermined gap therebetween; and
biasing means for upwardly biasing the movable piece.
The apparatus according to Claim 1, wherein said paper thickness sensing means comprises:
a piezo-electric element for generating different voltages in accordance with thickness difference of the receiver paper, said piezoelectric element being mounted on the paper feed base so as to be spaced apart therefrom by a predetermined gap.
The apparatus according to Claim 1, wherein said paper thickness sensing means comprises:
a seesaw type lever hinged to a predetermined position in order to change a seesaw angle thereof in accordance with the thickness of the receiver paper;
biasing means for upwardly biasing said seesaw type lever, said biasing means being mounted on a mounting plate which is disposed at a predetermined position;
a light emitting element which is disposed on the mounting plate; and
a light receiving element for receiving a light emitted from said light emitting element in order to sense a displacement of the seesaw type lever, said light receiving element being disposed on the mounting plate so as to be spaced apart from said light emitting element by a predetermined distance.
The apparatus according to Claim 9, wherein said paper thickness sensing means further comprises:
a light intercepting piece which is axially secured to a rear end of the seesaw type lever and movably disposed between said light emitting and light receiving elements in order to intercept the light emitted from the light emitting element in accordance with a displacemt of the seesaw type lever, thereby allowing the light receiving element to sense an abnormal feeding of the receive paper.
The apparatus according to Claim 1, wherein said paper jam control means comprises:
a paper sensing member for determining whether the receiver paper which has been fed from the paper cartridge passes through a nip between said developing rollers; and
a reversed-tension member for providing the reversed tension for the receiver paper which passes through said nip between the developing rollers, said reversed-tension member being disposed on a paper feed base.
The apparatus according to Claim 11, wherein said reversed-tension member comprises a pair of rollers which are able to be selectively driven.
The apparatus according to Claim 1, wherein said control means comprises:
a paper feed motor for driving a paper feed roller and a reversed-tension member to rotate in forward or reversed direction;
a microcomputer for controlling a forward feeding, a reversed tension and a reversed-directional feeding of said receiver paper in accordance with control signals outputted from a paper misfeeding signal generating means of said paper thickness sensing means and a paper sensing member of said paper jam control means, respectively;
a paper feed motor driving part for driving said paper feed motor under the control of said microcomputer; and
rotating power transmission means for cutting off rotating power, said rotating power being to be transmitted to the paper feed roller, when the receiver paper is applied with the reversed tension under the control of the microcomputer.
The apparatus according to Claim 13, wherein said microcomputer controls said reversed-tension member to rotate at a rotating linear velocity which is less than a rotating linear velocity of said developing rollers or to rotate in a reversed direction, and also controls said rotating power transmission means to cut off said rotating power which is to be transmitted to the paper feed roller when a front edge of the receiver paper passes through a nip between said developing rollers.