Unit for and method of registering/feeding paper and image forming apparatus using the same
A paper registering/feeding unit that registers a sheet of print paper and feeds it to a printing unit, a method of registering/feeding a sheet of print paper, and an image forming apparatus using the same are provided. A paper registering/feeding unit includes a rotatable pick-up roller including an effective contact surface which contacts a sheet of print paper to pick up the print paper. The paper registering/feeding unit also includes a pair of registration rollers in contact with each other to form a nip along the pathway of the print paper, a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers, and a controller that controls a rotation of the registration rollers based on a time of sensing the end of the print paper by the sensor.
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This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application Nos. 10-2005-0048429 and 10-2005-95529, filed on Jun. 7, 2005 and Oct. 11, 2005, respectively, in the Korean Intellectual Property Office, the entire disclosures of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus including a paper registering/feeding unit that registers a sheet of print paper and feeds the paper to a printing unit, and a method of registering/feeding the same.
2. Description of the Related Art
An image forming apparatus prints an image on a sheet of print paper. The image forming apparatus includes a printing unit that forms an image on a sheet of print paper and a paper registering/feeding unit that picks up, registers, and feeds a sheet of print paper to the printing unit.
When the front end of the print paper P picked up by the pick-up roller 12 and transported, preferably upwardly, toward the registration roller 25 by the paper feeding rollers 15, the print paper P pushes the lever 21 and the photo sensor 20 generates a sensing signal which corresponds to the front end of the print paper P. The sensing signal is transmitted to a controller (not illustrated). The controller controls the paper feeding rollers 15 to pause transportation of the print paper P when a nip N of the registration rollers 25 hinders transportation of the front portion of the print paper P and a curl C is formed on the front portion of the print paper P. The controller pauses transportation of the print paper P after a predetermined time-lag from a time of sensing the front end of the print paper P. The front end of the print paper P is registered via the the curl C formation during standby for printing. Then, the print paper P is transported again to a printing unit (not illustrated) by the rotation of the registration rollers 25 and the paper feeding rollers 15.
There are drawbacks with the conventional unit. Since the conventional paper registering/feeding unit 10 uses the paper feeding rollers 15 between the pick-up roller 12 and the registration rollers 25, it has a relatively complicated structure, high manufacturing costs, and limits the minimization of the image forming apparatus.
Accordingly, there is a need for an improved paper registering/feeding unit which does not position paper feeding rollers between a pick-up roller and registration rollers and an image forming apparatus having the same.
SUMMARY OF THE INVENTIONAn aspect of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a paper registering/feeding unit that does not use paper feeding rollers between a pick-up roller and registration rollers and an image forming apparatus having the same.
The exemplary embodiments of the present invention also provide a method of registering/feeding a print paper using the paper registering/feeding unit.
According to an aspect of the present invention, there is provided a paper registering/feeding unit including a rotatable pick-up roller including a contact surface which contacts a sheet of print paper to pick up the print paper. The paper registering/feeding unit also includes a pair of registration rollers in contact with each other form a nip along the pathway of the print paper, a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers, and a controller that controls the rotation of the registration rollers based on the time of sensing the front end of the print paper by the sensor. The length of the arc of the contact surface is greater than the distance between the pick-up roller and the nip of the registration rollers along the pathway of the print paper.
The controller may have a unit that rotates the registration rollers after a first time-lag from a time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the transportation of the front end of the registered print paper passing through the nip so that the front end of the print paper is discontinued and on standby for printing.
The paper registering/feeding unit may include no additional rollers for feeding print paper between the pick-up roller and the registration rollers.
The paper registering/feeding unit may further include a clutch that selectively connects and disconnects the registration rollers to and from a driving source for driving the registration rollers according to control signals generated by the controller.
According to another aspect of the present invention, there is provided an image forming apparatus having a printing unit that print an image on print paper and a paper registering/feeding unit that registers and feeds the print paper to the printing unit. The paper registering/feeding unit includes a rotatable pick-up roller inlcuding a contact surface which contacts a sheet of print paper to pick up the print paper. The paper registering/feeding unit also includes a pair of registration rollers in contact with each other forming a nip along the pathway of the print paper, a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers, and a controller that controls the rotation of the registration rollers based on the time of sensing the front end of the print paper P by the sensor. The length of the arc of the contact surface is greater than the distance between the pick-up roller and the nip of the registration rollers along the pathway of the print paper.
The controller may have a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
The image forming apparatus may include no additional rollers for feeding the print paper between the pick-up roller and the registration rollers.
The image forming apparatus may further include a clutch that selectively connects and disconnects the registration rollers to and from a driving source for driving the registration roller according to control signals generated by the controller.
According to still another aspect of the present invention, there is provided a method of registering/feeding print paper, including picking up and transporting print paper toward a nip of registration rollers by rotating a pick-up roller. The method also includes the steps of sensing the approach of the front end of the print paper toward the nip, driving the registration rollers after a first time-lag from a time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and pausing the registration rollers after a second time-lag from the time of sensing the front end of the print paper toward the nip so that the transportation of the front end of the print paper registered and passed through the nip is discontinued and on standby for printing.
In the transporting of the print paper, the print paper may be directly transported to the nip of the registration rollers by only the transportation force of the pick-up roller.
According to yet another aspect of the present invention, there is provided a paper registering/feeding unit including a rotatable pick-up roller that has an effective contact surface which contacts a sheet of print paper to pick up the print paper. The paper registering/feeding unit also includes a pair of registration rollers in contact with each other to form a nip along the pathway of the print paper, a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers, and a controller that controls a rotation of the registration rollers based on a time of sensing the front end of the print paper by the sensor. The length of the arc of the effective contact surface is greater than the distance between the position where the pick-up roller initially contacts the print paper for feeding and the nip of the registration rollers along the pathway of the print paper.
The controller may include a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
The paper registering/feeding unit may include no additional rollers for feeding the print paper between the pick-up roller and the registration rollers.
The image forming apparatus further includes a clutch that selectively connects and disconnects the registration rollers to and from the driving source for driving the registration roller according to control signals generated by the controller.
According to further another aspect of the present invention, there is provided an image forming apparatus having a printing unit that prints an image on print paper and a paper registering/feeding unit that registers and feeds the print paper to the printing unit. The paper registering/feeding unit includes a rotatable pick-up roller including an effective contact surface which contacts a sheet of print paper to pick up the print paper. The paper registering/feeding unit also includes a pair of registration rollers in contact with each other to form a nip along the pathway of the print paper, a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers, and a controller that controls rotation of the registration rollers based on a time of sensing the front end of the print paper by the sensor. The length of the arc of the effective contact surface is greater than the distance between the position where the pick-up roller initially contacts the print paper for feeding and the nip of the registration rollers along the pathway of the print paper.
The controller may includes a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
The image forming apparatus may include no additional rollers for feeding print paper between the pick-up roller and the registration rollers.
The paper registering/feeding unit further includes a clutch that selectively connects and disconnects the registration rollers to and from the driving source for driving the registration roller according to control signals generated by the controller.
Other objects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGSThe above and other objects, and features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:
Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTSThe matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the exemplary embodiments of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The developer unit 10 includes a housing 111 in which a developer, such as toner is stored. The developer unit 110 also includes a photosensitive medium 115 on which an electrostatic latent image is formed by light scanning, a charging roller 113 that charges the photosensitive medium 115, and a waste toner cleaner 114 that removes waste toner residues from the photosensitive medium 115′. The developer unit 110 further includes a developing roller 117 that develops an image on the outer circumference of the photosensitive medium 115 by supplying the toner to an electrostatic latent image formed on the outer circumference of the photosensitive medium 115, a doctor blade 118 that controls the thickness of the toner attached on the surface of the developing roller 117, and a supplying roller 119 that supplies the toner to the developing roller 1 17. In addition, the housing 111 includes an agitator 121 that agitates the toner to prevent hardening. The developer unit 110 is preferably of a cartridge type and can be replaced with a new one when the developer therein is exhausted.
The transfer roller 125 is positioned to form a transfer nip Nt by contacting the photosensitive medium 115 and presses the print paper P onto the photosensitive medium 115. Therefore, a visible image developed on the outer circumference of the photosensitive medium 115 can be transported onto the print paper P passing through the transfer nip Nt.
The fixing unit 130 includes a heat roller 131 and a pressure roller 133 which face each other. When a sheet of print paper P on which the visible image is transferred passes through a gap between the heat roller 131 and the pressure roller 133, the visible image is printed on the print paper P by heat and pressure. A plurality of paper discharging rollers deliver the image printed paper P to a paper tray 102 outside the case 101 and are mounted above the fixing unit 130.
The paper registering/feeding unit 140 includes a paper feed cassette 141 in which sheets of print paper P are loaded, a pick-up roller 150 having a semicircular surface, and a friction pad 147 which contacts a contact surface 151 of the pick-up roller 150. Consequently, a sheet of printing paper P is picked up. The paper registering/feeding unit also includes a first and second registration rollers 161 and 163 that registers and feeds the print paper P picked up to the printing unit; a photo sensor 165 that senses the approach of the print paper P; and a lever 167.
The printing process of the image forming apparatus 100 having the above-described structures is as follows. The photosensitive medium 115 is charged to a predetermined electric potential by the charging roller 113 and induced by scanning light L from the light-scanning unit 127. Thus, an electrostatic latent image corresponding to an image to be printed is formed on the outer circumference of the photosensitive medium 115. A toner stored in the housing 111 is supplied to the photosensitive medium 115. Then, the electrostatic latent image is formed thereon by a supply roller 119 and a developing roller 117 and a visible image is developed on the outer circumference of the photosensitive medium 115. Meanwhile, a sheet of print paper P is picked up by the pick-up roller 150, registered and fed by the pair of registration rollers 161 and 163, and passes through the transfer nip Nt between the photosensitive medium 115 and the transfer roller 125. Here, the visible image developed on the outer circumference of the photosensitive medium 115 is transferred onto the surface of the print paper P facing the photosensitive medium 115. The image transferred onto the print paper P is fixed on the print paper P by heat and pressure while passing through a fixing unit 130. Lastly, the paper is delivered by a pair of paper discharging rollers 135 and stacked on the paper tray 102.
Prior to the input of a print command into the image forming apparatus 100, as shown in
Meanwhile, the first registration roller 161 is rotated by a driving force of a driving source like a motor (not illustrated), while the second registration roller 163 is a passive roller that contacts the first registration roller 161, forms a nip N with the first registration roller 161, and is rotated by the first registration roller 161. The motor is connected to the first registration roller 161 via an electronic clutch 175, such as a power switching unit. The electronic clutch 175 selectively connects and disconnects the first registration roller 161 to and from the motor. The motor and the electronic clutch 175 are generally known to those of ordinary skill in the art, and thus a detailed description thereof will be omitted for clarity and conciseness.
The lever 167 includes one end 167a blocking a front end Pt of the print paper P transported toward the nip N and the other end 167b extended toward the photo sensor 165. The lever 167 can be rotated on a predetermined pivot shaft 168 located between the one end 167a and the other end 167b. Since the lever 167 is elastically biased, the lever 167 is pushed by the front end Pt of the print paper P transported toward the nip N to rotate clockwise on the pivot shaft 168, and then may return to the initial position after the tail end of the print paper P passes through the one end 167a of the lever 167. The rotation angle of the lever 167 may be limited by a stopper (not illustrated).
The photo sensor 165 includes a slit (not illustrated) which allows the other end 167b of the lever 167 to pass through it. The inner wall of the slit includes a light emitter (not illustrated) that radiates a laser and a light receiver (not illustrated) that receives the radiated laser. The photo sensor 165 is generally known to those of ordinary skill in the art, and thus a detailed description thereof will be omitted.
The paper registering/feeding unit 140 includes a controller 170 that controls the rotation of the registration rollers 161 and 163 with respect to a time of sensing the front end Pt of the print paper P by the photo sensor 165. The controller 170 is electrically connected to the photo sensor 165 to receive the sensing signal of the front end Pt of the print paper P from the photo sensor 165. The controller 170 is also electrically connected to the electronic clutch 175 to transmit a control signal to the electronic clutch 175 to control the rotation of the registration rollers 161 and 163.
Hereinafter, the operation of the registering/feeding unit 140 having the above-described structures will be described.
When a print command is input to the image forming apparatus 100, (see
When the front end Pt of the print paper P is upwardly transported to push up the one end 167a of the lever 167, as shown in
Referring to
As shown in
Referring to
After that, the controller 170 transmits a driving control signal for driving the registration rollers 161 and 163 to the electronic clutch 175 after an appropriate time-lag so that the print paper P can pass through the transfer nip Nt at the corresponding time when a visible image developed on the photosensitive medium 115 (see
Referring to
The pick-up roller 250 includes an effective contact surface 251 contacting the print paper for transporting the paper and a detached surface 252 that does not contact the print paper P. The paper registering/feeding unit 240 does not include an additional roller for feeding the print paper P between the pick-up roller 250 and the pair of the registration rollers 261 and 263. The front end Pt of the print paper P is transported toward the nip N of the registration roller 261 and 263 by only a frictional force between the effective contact surface 251 of the pick-up roller 150 and the print paper P.
In order for the front end Pt of the picked up print paper P to reach the nip N, the arc length d1′ of the effective contact surface 251 is greater than the distance d2′ of a pathway R2 which is a portion of the entire pathway R (see
Hereinafter, the operation of the registering/feeding unit 240 will be described.
When a print command is input to the image forming apparatus 100, (see
When a print command is input to the image forming apparatus 100, (see
When the front end Pt of the print paper P is upwardly transported to push up the one end 267a of the lever 267, as shown in
Referring to
As shown in
Referring to
After that, the controller 270 transmits a driving control signal for driving the registration rollers 261 and 263 to the electronic clutch 275 after an appropriate time-lag so that the print paper P can pass through the transfer nip Nt at the corresponding time when a visible image developed on the photosensitive medium 115 (see
The paper registering/feeding unit according to the exemplary embodiments of the present invention has a simple structure because it does not use additional rollers between a pick-up roller and registration rollers. Therefore, the paper registering/feeding unit has relatively high reliability, reduced manufacturing costs, and can minimize the size of an image forming apparatus.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the exemplary embodiments of the present invention as defined by the following claims. For example, the image forming apparatus including the paper registering/feeding unit of the exemplary embodiments of the present invention may be an ink jet printer or an intermediate transfer type color laser printer. Therefore, the scope of the exemplary embodiments of the present invention is defined by the following claims.
Claims
1. A paper registering/feeding unit comprising:
- a rotatable pick-up roller including a contact surface which contacts a sheet of print paper to pick up the print paper;
- a plurality of registration rollers in contact with each other to form a nip along the pathway of the print paper;
- a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers; and
- a controller that controls rotation of the registration rollers based on a time of sensing the front end of the print paper by the sensor,
- wherein the length of the arc of the contact surface is greater than the distance between the pick-up roller and the nip of the registration rollers along the pathway of the print paper.
2. The paper registering/feeding unit of claim 1, wherein the controller comprises a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper curls, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
3. The paper registering/feeding unit of claim 1, wherein the paper registering/feeding unit comprises no additional rollers for feeding the print paper between the pick-up roller and the registration rollers.
4. The paper registering/feeding unit of claim 1, wherein the paper registering/feeding unit further comprises a clutch that selectively connects and disconnects the registration rollers to and from a driving source for driving the registration roller according to control signals generated by the controller.
5. An image forming apparatus having a printing unit that prints an image on print paper and a paper registering/feeding unit that registers and feeds the print paper to the printing unit, wherein the paper registering/feeding unit comprises:
- a rotatable pick-up roller including a contact surface which contacts a sheet of print paper to pick up the print paper;
- a plurality of registration rollers in contact with each other and forming a nip along the pathway of the print paper;
- a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers; and
- a controller that controls rotation of the registration rollers based on the time of sensing the front end of the print paper by the sensor,
- wherein the length of the arc of the contact surface is greater than the distance between the pick-up roller and the nip of the registration rollers along the pathway of the print paper.
6. The image forming apparatus of claim 5, wherein the controller comprises a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
7. The image forming apparatus of claim 5, wherein the image forming apparatus comprises no additional rollers for feeding print paper between the pick-up roller and the registration rollers.
8. The image forming apparatus of claim 5, wherein the image forming apparatus further comprises a clutch that selectively connects and disconnects the registration rollers to and from the driving source for driving the registration roller according to control signals generated by the controller.
9. A method of registering/feeding print paper, the method comprising:
- picking up and transporting the print paper toward a nip of registration rollers by rotating a pick-up roller;
- sensing the approach of the front end of the print paper toward the nip;
- driving the registration rollers after a first time-lag from a time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers; and
- pausing the registration rollers after a second time-lag from the time of sensing the front end of the print paper toward the nip so that the transportation of the front end of the print paper registered and passed through the nip is discontinued and on standby for printing.
10. The method of claim 9, wherein, in the transporting of the print paper, the print paper is directly transported to the nip of the registration rollers by only the transportation force of the pick-up roller.
11. A paper registering/feeding unit comprising;
- a rotatable pick-up roller including an effective contact surface which contacts a sheet of print paper to pick up the print paper;
- a pair of registration rollers in contact with each other to form a nip along the pathway of the print paper;
- a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers; and
- a controller that controls rotation of the registration rollers based on a time of sensing the front end of the print paper by the sensor,
- wherein the length of the arc of the effective contact surface is greater than the distance from the position where the pick-up roller initially contacts the print paper to the nip of the registration rollers along the pathway of the print paper.
12. The paper registering/feeding unit of claim 11, wherein the controller comprises a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
13. The paper registering/feeding unit of claim 11, wherein the paper registering/feeding unit comprises no additional rollers for feeding print paper between the pick-up roller and the registration rollers.
14. The paper registering/feeding unit of claim 11, wherein the image forming apparatus further comprises a clutch that selectively connects and disconnects the registration rollers to and from the driving source for driving the registration roller according to control signals generated by the controller.
15. An image forming apparatus having a printing unit that prints an image on print paper and a paper registering/feeding unit that registers and feeds the print paper to the printing unit, wherein the paper registering/feeding unit comprises:
- a rotatable pick-up roller including an effective contact surface which contacts a sheet of print paper to pick up the print paper;
- a pair of registration rollers in contact with each other to form a nip along the pathway of the print paper;
- a sensor sensing the approach of the front end of the print paper picked up by the pick-up roller toward the nip of the registration rollers; and
- a controller that controls rotation of the registration rollers based on a time of sensing the front end of the print paper by the sensor,
- wherein the length of the arc of the effective contact surface is greater than the distance from the position where the pick-up roller initially contacts the print paper to the nip of the registration rollers along the pathway of the print paper.
16. The image forming apparatus of claim 15, wherein the controller comprises a unit that rotates the registration rollers after a first time-lag from the time of sensing the front end of the print paper so that the front end of the print paper is curled, registered and passed through the nip of the registration rollers, and that pauses the registration rollers after a second time-lag from the time of sensing the front end of the registered print paper passing through the nip so that the transportation of the front end of the print paper is discontinued and on standby for printing.
17. The image forming apparatus of claim 15, wherein the image forming apparatus comprises no additional rollers for feeding print paper between the pick-up roller and the registration rollers.
18. The image forming apparatus of claim 15, wherein the image forming apparatus further comprises a clutch that selectively connects and disconnects the registration rollers to and from the driving source for driving the registration roller according to control signals generated by the controller.
Type: Application
Filed: Jan 10, 2006
Publication Date: Dec 21, 2006
Applicant:
Inventor: Gyeong-Ho Park (Suwon-si)
Application Number: 11/328,101
International Classification: B65H 9/04 (20060101);