KR20070024948A - Print medium picking up unit and image forming apparatus with the same - Google Patents

Abstract

A print medium pickup unit and an image forming apparatus with the same are provided to uniformly maintain a contact angle which is made when the print medium is contacted with a guide surface irrespective of the volume of print media loaded on a print medium cassette, thereby improving reliability of a pickup process. A print medium pickup unit(130) comprises the followings: a pick-up roller(131) for picking up a print medium; a knock-up plate(137) for liftably supporting a front end of the print medium; a pick-up lever(150) for contacting the print medium with the pick-up roller(131) by selectively lifting the knock-up plate(137); and a guide member(160) which has a guide surface tilt to guide front end of the picked-up print medium upwards, and is linked with elevation of the pick-up lever(150) so that a tile angle between the guide surface and a horizontal level can be changed.

Description

Print medium pick-up unit and image forming apparatus having same {Print medium picking up unit and image forming apparatus with the same}

1 and 2 are views illustrating the moment when a print medium is picked up by a conventional print medium pickup unit. FIG. 1 shows a case in which a large amount of print medium is loaded in a cassette. The figure shows the case.

3 is a cross-sectional view of an image forming apparatus according to a preferred embodiment of the present invention.

4 is a perspective view illustrating a cassette of a print medium pickup unit according to a preferred embodiment of the present invention.

5 is a perspective view illustrating a guide member and a pickup lever of a print medium pickup unit according to a preferred embodiment of the present invention.

6 and 7 are views illustrating the moment when a print medium is picked up by the print medium pickup unit of the present invention. FIG. 6 shows a case where a large amount of print medium is loaded in the cassette. It is a diagram showing the case.

<Description of the symbols for the main parts of the drawings>

100 ... Imager 110 ... Printer Engine

111 ... TPH 113 Plate Platen Roller

115 ... Ink Ribbon 125 ... Feed Rollers

127 ... badge roller 130 ... print media pickup unit

131 ... pickup roller 135 ... print media cassette

137 ... knock-up plate 150 ... pickup lever

153 ... Protrusion 160 ... Guide member

165 ... guide surface 167 ... slot

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a print medium pickup unit for picking up a print medium loaded on a print medium cassette sheet by sheet, and an image forming apparatus having the same.

The image forming apparatus may be classified into an electrophotographic method, an inkjet method, a thermal method, etc. according to a printing method of a printer engine for forming an image on a printing medium. The image forming apparatus loads a printing medium supplied to the printer engine and picks up the sheets one by one. A media pickup unit is commonly provided.

1 and 2 are views illustrating the moment when a print medium is picked up by a conventional print medium pickup unit. FIG. 1 shows a case in which a large amount of print medium is loaded in a cassette. It is a figure which shows the case.

1 and 2, a conventional print media pickup unit 10 includes a print media cassette 15 for loading a print medium S and detachably mounted on a main body (not shown) of an image forming apparatus. A pickup roller 20, a pickup lever 25, and a guide member 30 provided in the forming apparatus main body (not shown) are provided. The print media cassette 15 is hinged with a knock-up plate 17 for supporting the leading end of the print media S to be liftable. The pickup lever 25 lifts the knock-up plate 17 to contact the tip of the print medium S with the pickup roller 20, and the pickup roller 20 rotates with the print medium S in contact with the pickup roller 20. As shown in FIG. Pick up. The guide member 30 has an inclined guide surface 32 for guiding the picked up print medium S at an angle upward.

However, since the guide member 30 is fixed to the image forming apparatus main body (not shown) in the conventional print medium pickup unit 10, the print medium S is formed on the knock-up plate 17 as shown in FIG. The contact angle A1 formed between the extension line of the tip of the print medium S and the extension line of the guide surface 32 at the moment when the print medium S is picked up when a plurality of sheets are loaded, and the knock-up plate as shown in FIG. 2. When a few sheets of the print medium S are loaded on (17), the contact angles A2 differ from each other at the moment when the print medium S is picked up. Specifically, the contact angle A1 when a large number of print media S is stacked is smaller than the contact angle A2 when a small number of print media S is stacked. Accordingly, as shown in FIG. 1, when the contact angle A1 is large, friction between the tip of the print medium S and the guide surface 32 is large, and thus the print medium S may not be picked up and jam may occur. When the contact angle A2 is small as shown in FIG. 2, the friction between the tip of the print medium S and the guide surface 32 is too small, which increases the possibility of picking up a plurality of print media S at once. In short, there is a problem that the pickup reliability is poor.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is a technical object of the present invention to provide a print medium pickup unit capable of reliable pickup regardless of the number of printed print media, and an image forming apparatus having the same.

Another object of the present invention is to provide a printing medium pickup unit in which the contact angle between the tip of the printing medium and the guide surface of the guide member is uniformly maintained within a predetermined range.

In order to achieve the above technical problem, the present invention, the pickup roller for picking up the print medium; A knock-up plate supporting the leading end of the printing medium in a liftable manner; A pickup lever for selectively raising the knockup plate to contact the print medium and the pickup roller; And a guide member inclined so as to guide the leading end of the picked up print medium upward, the guide member being configured to change the inclination angle of the guide surface with the horizontal plane in connection with the lift of the pickup lever.

As the pick-up lever is raised, the inclination angle of the guide surface is increased so that the contact angle formed by the extension line of the print media tip and the guide line is uniform within a certain range regardless of the number of print media supported on the knock-up plate. It provides a print media pickup unit, characterized in that configured to be held.

Preferably, the contact angle may be configured to remain uniform between 100 degrees and 105 degrees.

Preferably, the pickup lever is provided pivotally about a first axis, and has a projection for lifting along a curved path about the first axis,

The guide member may be pivotally provided about a second axis, and may include a slot that receives the protrusion and extends upwardly in a direction crossing the curved path of the protrusion from the inside to the outside.

In addition, the present invention provides a print media pickup unit comprising a print medium pickup unit for loading a print medium and picking up sheet by sheet, and a printer engine for printing an image on the picked up print medium, wherein the print medium pickup unit comprises:

A pickup roller for picking up the print medium by contact; A knock-up plate supporting the leading end of the printing medium in a liftable manner; A pickup lever for selectively raising the knockup plate to contact the print medium and the pickup roller; And a guide member inclined so as to guide the leading end of the picked up print medium upward, the guide member being configured to change the inclination angle of the guide surface with the horizontal plane in connection with the lift of the pickup lever.

As the pick-up lever is raised, the inclination angle of the guide surface is increased so that the contact angle formed by the extension line of the print media tip and the guide line is uniform within a certain range regardless of the number of print media supported on the knock-up plate. An image forming apparatus is configured to be maintained.

Preferably, the printer engine includes an ink ribbon in which a dye for developing a print medium is soaked, and a thermal print head (TPH) for heating the ink ribbon to sublimate the soaked dye to penetrate the print medium. can do.

Hereinafter, a print media pickup unit and an image forming apparatus including the same according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a cross-sectional view showing an image forming apparatus according to a preferred embodiment of the present invention, FIG. 4 is a perspective view showing a cassette of a print medium pickup unit according to a preferred embodiment of the present invention, and FIG. 5 is a preferred view of the present invention. A perspective view of the guide member and the pickup lever of the print media pickup unit according to the embodiment.

Referring to FIG. 3, the image forming apparatus 100 includes a print medium pickup unit 130 for loading a print medium S and picking up sheet by sheet, and a printer engine for printing an image on the picked up print medium S. FIG. (printer engine 110). The printer engine 110 is provided inside the case 102 forming an exterior of the image forming apparatus main body 101.

The printer engine 110 may apply ink to the ink ribbon 115 in which the dye for coloring the print medium S is soaked, and heat the ink ribbon 115 to sublimate the dye soaked in the print medium S. It is provided with a TPH (Thermal Print Head, 111) to color the print medium (S) by soaking. The TPH 111 has a plurality of heat generating elements (not shown) arranged in the width direction of the print medium S, and a part of the plurality of heat generating elements selectively generates heat, so that the print medium S may be Induces color development The ink ribbon 115 is wound around and supported by a pair of ribbon support wheels 117 and 118 to maintain tension. Below the TPH 111, a platen roller 113 for pressing the print medium S and the ink ribbon 115 toward the heating element (not shown) side of the TPH 111 is provided.

In addition, inside the image forming apparatus main body 101, the printing medium S picked up by the printing medium pick-up unit 130 is fed between the TPH 111 and the platen roller 113, and in the opposite direction of the feeding in the color development process. And a delivery roller 127 for discharging the printed medium S, which has been printed, to the outside of the image forming apparatus main body 101. The feed roller 125 and the discharge roller 127 are each provided with a pair of rollers facing each other, one of the pair of rollers is a driving roller, the other is the driving roller It is an idle roller that follows the rotation.

The image forming process of the image forming apparatus 100 will be described in detail below. The print media S loaded on the print media cassette 135 is picked up one by one by the pickup roller 121, and the picked print media S is spaced apart from each other by the feed roller 125. It is fed between the platen rollers 113. The feed roller 125 stops rotating while the rear end of the print medium S is held by the feed roller 125, and the TPH 111 transfers the ink ribbon 115 and the print medium S to the platen roller. The platen roller 113 is in close contact with the platen roller 113 while interposed therebetween.

The feed roller 125 is rotated in a direction opposite to the feeding direction to pull the print medium S interposed between the TPH 111 and the platen roller 113 to transfer in the direction of the discharge roller 127.

The ink ribbon 115 travels at the same speed as the conveying speed of the print medium S, and a plurality of heating elements (not shown) of the TPH 111 selectively generate heat to sublimate the dye contained in the ink ribbon to print medium. By developing (S), an image is formed on the print medium (S). The printing medium S on which the image is formed is discharged to the outside of the image forming apparatus main body 101 by the discharge roller 127.

The print medium pickup unit 130 includes a print medium cassette 135 for loading the print medium S and detachably mounted to the image forming apparatus main body 101. A knock-up plate 137 is connected to the base frame 136a of the print medium cassette 135 in the print medium cassette 135 to support the leading end of the print medium S. ) Is provided. In addition, the print medium pickup unit 130 selectively raises the pickup roller 131 for contact-picking the print medium S to the image forming apparatus main body 101 and the knock-up plate 137 to print medium S. FIG. ) And a pickup lever 15 for contacting the pickup roller 131, and a guide member 160 for guiding the tip of the picked up print medium S upward.

Referring to FIG. 4, the print medium cassette 135 includes a base frame 136a and a cover 136b hinged to the base frame 136a. An interior space in which the print medium S is loaded is provided in the base frame 136a. The cover 136b covers the open upper side of the base frame 136a. When the cover 136b is opened, it is easy to load the print medium S into the base frame 136a.

On the other hand, when the print medium cassette 135 is mounted on the image forming apparatus main body 101 at the front portion of the base frame 136a, the tip of the pickup lever 150 (see FIG. 3) is positioned below the knock-up plate 137. A pickup lever entry part 142 is formed to be able to enter, and guide member accommodation parts 144 are formed at both sides of the pickup lever entrance part 142.

5 to 7, the pickup lever 150 is pivotally mounted to the image forming apparatus main body 101 (refer to FIG. 3) about the first shaft 151. The central portion of the pickup lever 150 is provided with a protrusion 153 accommodated in the slot 167 of the guide member 160. The protrusion 153 moves up and down along the curved path 155 around the first axis 151 as the pickup lever 150 pivots.

The guide member 160 is pivotally mounted to the image forming apparatus main body 101 (refer to FIG. 3) about the second shaft 161. For this purpose, the guide member 160 is mounted on the upper end of the guide member 160. ) Is provided with a mounting projection 162 coaxially formed. In addition, the inclined guide surface 165 is formed on the opposite side of the print medium to guide the leading end of the picked up print medium S, and the projection 153 of the pickup lever 150 is accommodated in the lower side. Slot 167 is formed. The slot 167 extends upwardly in a direction transversely from the inside of the path 155 to the curved path 155 on which the protrusion 153 moves up and down. Reference numeral 168 in FIGS. 6 and 7 is an imaginary line showing the extending direction of the slot 167. The slot 167 may be formed to burst into the lower surface of the guide member 160 to easily fasten the protrusion 153.

Hereinafter, a process of picking up the print medium S of the print medium pickup unit 130 will be described in detail.

When the print medium cassette 135 on which the print medium S is loaded is mounted on the image forming apparatus main body 101, the pickup lever 150 enters through the pickup lever entry portion 142 of the front end of the base frame 136a. Located below the knock up plate 137. In addition, the pickup roller 131 is positioned above the opening 140 on the upper surface of the base frame 136a.

When printing starts, the pickup roller 131 rotates, and at the same time, the pickup lever 150 presses the knockup plate 137 to raise it. As a result, the printing medium S loaded at the top of the knock-up plate 137 proceeds forward due to the friction with the pickup roller 131, so that the tip of the printing medium S collides with the guide surface 165.

On the other hand, when the pickup lever 150 is raised due to the characteristic of the extension direction 168 of the slot 167 and the curved path 155 of the protrusion 153, the guide member 160 is the second shaft 161. Rotate in a counterclockwise direction, the rotation angle of which is proportional to the rising width of the pickup lever 150. Therefore, when a plurality of print media S are stacked on the knock-up plate 137 as shown in FIG. 6, the rising width of the pickup lever 150 is relatively small, so that the rotation angle of the guide member 160 is also relative. As shown in FIG. 7, when a small number of printing mediums S are stacked on the knock-up plate 137, the rising width of the pickup lever 150 is relatively large, and the rotation angle of the guide member 160 is also increased. Relatively large. Accordingly, the inclination angle T1 formed by the guide surface 165 in FIG. 6 and the horizontal plane is smaller than the inclination angle T2 in FIG. 7. 6, the inclination angle B1 of the knockup plate 137 is smaller than the inclination angle B2 of the knockup plate 137 in FIG. 7. Therefore, if the extension direction 168 of the slot 167 and the curved path 155 of the projection 153 are appropriately set, the print medium S may be independent of the quantity of the print medium S loaded on the knockup plate 137. The contact angle between the extension line of the tip and the extension line of the guide surface 165 can be maintained uniformly within a predetermined range.

The contact angle to prevent pick-up failure and multiple pickups may vary depending on conditions such as the friction coefficient of the guide surface 165, the rotational speed of the pickup roller 131, or the friction coefficient, but is generally known to be 100 degrees to 105 degrees. have. According to the preferred embodiment shown in Figs. 6 and 7, the contact angle A1 'when a large number of print media S is loaded and the contact angle A2' when a small number of print media S is stacked ) May be maintained uniformly between 100 degrees and 105 degrees.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. For example, unlike the embodiment shown in the drawings, the print media pickup unit of the present invention may be applied to a direct color type thermal image forming apparatus, and may also be applied to an inkjet or electrophotographic image forming apparatus. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

According to the printing medium pickup unit of the present invention and the image forming apparatus having the same, the pickup angle is maintained by maintaining the contact angle uniformly when the printing medium contacts the guide surface, regardless of the number of printing media loaded on the printing medium cassette. Reliability is improved.

Claims (5)

A pickup roller for picking up the print medium by contact; A knock-up plate supporting the leading end of the printing medium in a liftable manner; A pickup lever for selectively raising the knockup plate to contact the print medium and the pickup roller; And a guide member inclined so as to guide the leading end of the picked up print medium upward, the guide member being configured to change the inclination angle of the guide surface with the horizontal plane in connection with the lift of the pickup lever. As the pick-up lever is raised, the inclination angle of the guide surface is increased so that the contact angle formed by the extension line of the print media tip and the guide line is uniform within a certain range regardless of the number of print media supported on the knock-up plate. Print media pickup unit, characterized in that configured to be held. According to claim 1, And the contact angle is configured to be maintained uniformly between 100 degrees and 105 degrees. According to claim 1, The pickup lever is provided to be pivotable about a first axis, and has a projection for lifting along a curved path about the first axis, And the guide member is pivotally provided about a second axis, and has a slot which receives the protrusion and extends upwardly in a direction crossing the curved path of the protrusion from the inside to the outside. An image forming apparatus comprising a print medium pickup unit for loading a print medium and picking up sheet by sheet, and a printer engine for printing an image on the picked up print medium, wherein the print medium pickup unit comprises: A pickup roller for picking up the print medium by contact; A knock-up plate supporting the leading end of the printing medium in a liftable manner; A pickup lever for selectively raising the knockup plate to contact the print medium and the pickup roller; And a guide member inclined so as to guide the leading end of the picked up print medium upward, the guide member being configured to change the inclination angle of the guide surface with the horizontal plane in connection with the lift of the pickup lever. As the pick-up lever is raised, the inclination angle of the guide surface is increased so that the contact angle formed by the extension line of the print media tip and the guide line is uniform within a certain range regardless of the number of print media supported on the knock-up plate. And an image forming apparatus configured to be maintained. The method of claim 4, wherein The printer engine includes an ink ribbon in which a dye for developing a print medium is soaked, and a TPH (Thermal Print Head) for applying heat to the ink ribbon to sublimate the soaked dye to penetrate the print medium. Forming device.

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