JPH0529764U - Printer paper feed mechanism - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent misalignment of printing even when using printing paper, such as copy printing media, where multiple sheets of paper are stacked. [Structure] The paper transport path behind the discharge rollers is
The printing paper is bent and guided in a direction opposite to the winding direction of the printing paper around the platen.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a paper feed mechanism of a printer that prevents printing misalignment even when a print paper such as a copy print medium, which is formed by stacking a plurality of paper sheets, is used.

[0002]

[Prior Art]

 FIG. 4 and FIG. 5 show the main configuration of a conventional printer, FIG. 4 is a perspective view thereof, and FIG. 5 is a side view thereof. 4 and 5, in this printer, a platen 101 is provided at the printing position, and a print head 102 and a ribbon protector 103 are arranged facing the platen 101. The platen 101 is rotated by a pulse motor (not shown), and although not shown, a belt is stretched between the rotary shaft 105 of the platen 101 and the output gear of the pulse motor. With this belt, the rotation of the pulse motor can be transmitted to the platen 101 side.

A paper chute 108, which is provided below the printing position so as to surround the platen 101 from the back side to the front side of the platen 101, and a printing paper 109 serving as a printing medium are paper chute. A sheet guide 110 for guiding the platen 101 from the back side to the front side printing position is disposed along the lower surface of 108. Note that the print paper 109 here is an example of a copy print medium capable of performing copy printing by sending a plurality of print papers in an overlapping state, and the print paper 109 is continuously printed for a plurality of sheets. It is formed like a form. In addition, sprocket holes 113 (see FIG. 4) are repeatedly formed on both the left and right sides of the printing paper 109 at equal intervals, and a sewing machine for easy separation is provided in the middle of the length direction. I have my eyes on it. Then, the continuous printing paper 109 with the sprocket holes is brought into a state in which the sprocket holes 113 are engaged with the pins 112 of the pair of pin tractors 111 disposed on the left and right sides behind the sheet guide 110, respectively. When the pin tractor 111 is set and is driven, the pin tractor 111 is pushed out and sent by the pin 112, and the same pulse motor as that of the platen 101 is used as a drive source of each pin tractor 111. That is, gears 115, 116, 117 and 118 are sequentially interposed between the rotary shaft 114 of the pin tractor 111 and the rotary shaft 105 of the platen 101, and the driving force from the pulse motor transmitted to the platen 101 is transmitted. It is in a state of being transmitted to the pin tractor 111 via the rotating shaft 105 and the gears 115, 116, 117 and 118.

On the other hand, above the printing position, above the ribbon protector 103, a guide rib 123 and the like protruding from a cover (not shown) are arranged, and above the platen 101. A separator frame 125 and the like are arranged. Further, a shaft 126 is rotatably attached to the separator frame 125 while being parallel to the platen 101. Further, a plurality of (four in this embodiment) discharge rollers 127 for sandwiching and feeding the printing paper 109 with the guide ribs 123 are attached to the shaft 126 so as to be integrally rotatable. Gears 128 are attached to both ends of the shaft 126 so as to be integrally rotatable. The gear 128 is power-coupled to the gear 115 via the gear 129, and is in a state of rotating in association with the platen 101 and the pin tractor 111. In addition, the print paper feed amount by the discharge roller 127 is set to be about 10 percent (%) larger than the feed amount by the focus collector 111.

Next, the operation of the paper feeding mechanism will be described. First, the left and right sprocket holes 113 are engaged with the pins 112 to set the printing paper 109 on the pair of left and right pin tractors 111, and the paper feeding control system is turned on by a paper loading switch (not shown). As a result, the pulse motor rotates, and the pin tractor 111 is driven together with the platen 101 and the discharge roller 127. In addition, the pin tractor 111 sends the printing paper 109 from the back surface of the platen 101 so as to be pushed between the sheet guide 110 and the paper chute 108. Then, the printing paper 109 is wound around the platen 101 and sent to the printing position by the guide of the first paper transport path 131 composed of the sheet guide 110 and the paper chute 108. Then, when a print command is sent from the outside, printing is started, and each time a line feed command is received, printing is repeated while feeding the paper by the line feed command amount. Then, the leading end of the printing paper 109 advances into the second paper transport path 132 formed by the guide rib 123 and the separator frame 125, and when the leading end abuts the guide rib 123, the guide rib 123 guides it to the ejection roller 127 side. To be done. Further, when the leading edge of the print sheet 109 is caught between the guide rib 123 and the discharge roller 127, the print sheet 109 is sent to the rear of the second sheet transport path 132 with the feeding by the discharge roller 127.

[0006]

[Problems to be solved by the device]

 As described above, in the paper feeding mechanism of the conventional printer, the printing paper 109 fed by the push-in type pin tractor 111 from the back side of the platen 101 is guided to the printing position by the first paper feeding path 131, At this printing position, the platen 101 is wound from the lower side and fed upward, and further guided in the second sheet conveying path 132, and in the second conveying path 132, the guide rib 123 and the discharge roller 127 are formed. Then, a substantially U-shaped paper traveling path is used so as to feed the paper to the rear side of the second paper conveying path 132, that is, to the back side of the platen 101. However, with such a structure, when a print sheet for copying is used, in which a plurality of print sheets are sent in a stacked state and copied and printed, as shown in FIG. 6, the inside of the platen 101 which contacts the platen 101 is used. There is a difference in the feed amount between the print sheet 109a and the outer print sheet 109b. That is, when the angle between the regions where the printing paper 109 is in contact with the platen 101 is θ, the diameter of the platen 101 is d, and the total thickness of the printing paper 109 is t, the inner feed amount per unit time is (dt / 2), the outer feed is (d + t) / 2. For this reason, when the paper is fed, misalignment occurs between the layers of the print sheets that are overlapped with each other to cause misregistration, and the print quality is deteriorated. However, there is a problem that troubles such as paper jams are likely to occur.

The present invention has been made in view of the above problems, and an object thereof is to provide a U-shaped printing paper running path when a plurality of printing papers such as copy paper are used. It is an object of the present invention to provide a paper feeding mechanism of a printer having a structure capable of improving the printing quality and the reliability of paper feeding by preventing the interlayer misalignment and the paper jam caused by the passage.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the paper feeding mechanism of the printer according to the present invention includes a first paper feeding path for guiding the printing paper fed from the back side of the platen to the front side of the platen and the front side of the platen. In addition to the second paper transport path for guiding the passed printing paper to the back side of the platen, a paper transport path formed in a substantially U shape is provided, and the inside of the first paper transport path is provided. A pin tractor for feeding the print sheet to the rear side, and a discharge roller for conveying the print sheet in the second sheet conveying path to the rear side. The platen, the pin tractor, and the discharge roller convey the print sheet. A guide for bending the print sheet in a direction opposite to the direction in which the print sheet winds around the platen, in a portion of the second sheet transport path that is behind the discharge roller of the second sheet transport path. Are those that you have configured so that.

[0009]

[Action]

 According to this configuration, when the printing paper is bent and guided in the direction opposite to the winding direction around the platen at the paper conveyance path portion on the rear side of the discharge roller, the inside of the bent portion is fed. Between the feed amount and the feed amount on the outer side, the difference between the feed amount of the inner and outer print sheets caused by the printing paper wrapping around the platen at the print position occurs, and The difference between the inner feed amount and the outer feed amount is canceled out. As a result, when the paper is fed, the misalignment between the overlapping print sheets is reduced.

[0010]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 show the main configuration of the printer of the present invention, FIG. 1 is a side view thereof, and FIG. 2 is a perspective view thereof. 1 and 2, in this printer, a platen 1 is provided at a printing position, and a print head 2 and a ribbon protector 3 are arranged so as to face the platen 1. The platen 1 is rotated by a pulse motor (not shown), and a belt is stretched between the rotary shaft 5 of the platen 1 and the output gear of the pulse motor (not shown). Is ready to transmit the rotation of the pulse motor to the platen side.

Further, below the printing position, a paper chute 8 provided so as to surround the platen 1 from the back side to the front side of the platen 1 and a printing paper 9 as a printing medium. A sheet guide 10 is provided below the paper chute 8 that forms a first paper transport path 31 for guiding the sheet from the back side to the front side of the platen 1 along the lower surface of the paper chute 8 together with the paper chute 8. Has been done. Note that the printing paper 9 here is an example of a copy printing medium that can be sent in a state where a plurality of printing papers are piled up to perform copy printing, and the printing paper 9 is a form in which a plurality of printing papers are consecutively printed. It is formed into a shape. In addition, sprocket holes 13 (see FIG. 2) are repeatedly formed on both the left and right sides of the printing paper 9 at equal intervals, and perforations for facilitating separation are provided in the middle of the length direction. It is included. Then, the continuous printing paper 9 with the sprocket holes is brought into a state in which the sprocket holes 13 are engaged with the pins 12 of the pair of pin tractors 11 arranged on the left and right sides behind the sheet guide 10. When the pin tractor 11 is driven, it is pushed out by the pin 12 and sent. The drive source of each pin tractor 11 is the same pulse motor as the platen 1. That is, gears 15, 16, 17, and 18 are sequentially interposed between the rotary shaft 14 of the pin tractor 11 and the rotary shaft 5 of the platen 1, and the driving force transmitted from the pulse motor to the platen 1 is transmitted to the platen 1. It is in a state of being transmitted to the pin tractor 11 via the rotary shaft 5 and gears 15, 16, 17, and 18.

On the other hand, above the printing position, above the ribbon protector 3, there are provided guide ribs 23 and the like protruding from a cover (not shown), and above the platen 1 there is a separator. A frame 25 and the like are provided. A shaft 26 is rotatably attached to the separator frame 25 in parallel with the platen 1. Further, a plurality of (four in this embodiment) discharge rollers 27 for sandwiching and feeding the printing paper 9 with the guide ribs 23 are attached to the shaft 26 so as to be integrally rotatable. Gears 28 are integrally rotatably attached to the both ends. The gear 28 is power-coupled to the gear 15 via the gear 29, and is in a state of rotating in conjunction with the platen 1 and the pin tractor 11.

Here, the guide ribs 23 and the separator frame 25 are used to guide the print sheet 9 sent through the front surface of the platen 1 to the rear side of the printer, that is, the rear side of the platen 1, at the printing position. The path 32 is formed, and the protrusion 23a of the guide rib 23 and the part 25a of the separator frame 25 are bent downward in the middle of the sheet conveying path immediately after the discharge roller 27. The entire second paper conveyance path 32 is formed in a substantially S-shape. As a result, the shape of the second sheet conveying path 32 is larger than that of the straight line AC connecting the point A on the surface of the discharge roller 27 and the point C on the upper end surface of the separator frame 25 in FIG. A portion indicated by the reference symbol B on the protruding portion 23a, that is, an inner surface of the protruding portion 23a is in a state of being protruded more inward. By the protrusion of the protruding portion 23a, the printing paper 9 immediately after passing through the discharge roller 27 is bent and guided in the direction opposite to the winding direction of the platen 1 (direction of arrow F in FIG. 1). Has been done. Also in this embodiment, the print paper feed amount by the discharge roller 27 is set to be about 10 percent (%) larger than the feed amount by the pin tractor 11.

Next, the operation of the paper feeding mechanism will be described. First, the left and right sprocket holes 13 are engaged with the pins 12 to set the printing paper 9 on the pair of left and right pin tractors 11, and the paper feeding control system is turned on by a paper loading switch (not shown). Then, the pulse motor rotates, and the pin tractor 11 is driven together with the platen 1 and the discharge roller 27. The pin tractor 11 feeds the printing paper 9 from the back surface of the platen 1 so that the printing paper 9 is pushed between the sheet guide 10 and the paper chute 8 to form the first paper consisting of the sheet guide 10 and the paper chute 8. The print sheet 9 is wound around the platen 1 by the guide of the transport path 31 and is sent to the print position. Then, when a print command is sent from the outside, printing is started, and each time a line feed command is received, printing is repeated while feeding paper by the amount of line feed command. Then, the front end of the printing paper 9 advances into the second paper transport path 32 formed by the guide rib 23 and the separator frame 25, and when its leading end abuts the guide rib 23, the guide rib 23 guides it to the discharge roller 27 side. It Further, when the leading edge of the print sheet 9 is caught between the guide rib 23 and the discharge roller 27, the print sheet 9 is sent to the back side of the platen 1 along with the feeding by the discharge roller 27.

In addition, the printing paper 9 thus sent to the rear side by the discharge roller 27 is wound around the platen 1 immediately after the discharge roller 27 by the projecting portion 23 a in the second paper transport passage 32. Contrary to the original direction, it is bent and transported once. Then, at this time, between the inner feed amount and the outer feed amount at this portion, the feeding of the inner and outer print sheets 9 which is caused by the print sheet 9 being wound around the platen 1 at the printing position. The opposite of the difference in quantity occurs, which offsets the difference.

The canceling effect due to the difference in the paper feed amount generated in the second paper transport path 32 is the straight line AB connecting the point A on the surface of the discharge roller 27 and the protruding portion 23a of the guide rib 23. Is determined by the angle θ formed by a straight line AC connecting the points C on the upper end surface of the separator frame 25 and the distance L between the point A on the surface of the discharge roller 27 and the point C on the upper surface of the separator frame 25. The angle .theta. Is set to 5 degrees or more and the distance L is set to 20 millimeters or more. Of course, other than this, there is no problem.

Therefore, according to the paper feeding mechanism of the printer according to the present embodiment, the deviation between the superposed print papers during paper feeding is reduced. This eliminates print misalignment, improves print quality, eliminates paper jams, and improves reliability.

Next, FIG. 3 shows a modified example of the paper feeding mechanism of the printer according to the present invention. In FIG. 3, the same reference numerals as those in FIGS. 1 and 2 are the same as those in FIGS. 1 and 2. It shows the thing. In the structure of this modification, the idle roller 33 is attached to the protruding portion 23a in the second paper transport path 32. Therefore, in this structure, the printing paper 9 sent to the rear side from the discharge roller 27 comes into contact with the idle roller 33 and is bent in the direction opposite to the direction in which the platen 11 is wound. However, the same effect as that of the above embodiment can be obtained.

In the above-described embodiment, the case where the printing paper 9 is a form has been described, but the same effect can be obtained not only for the form but also for a single form.

[0020]

[Effect of the device]

 As described above, according to the paper feeding mechanism of the printer according to the present invention, the printing paper is guided by being bent in the direction opposite to the winding direction of the platen at the paper conveying path portion on the rear side of the discharge roller. Between the inner feed amount and the outer feed amount in this bent portion, the feed amount of the inner and outer print sheets generated by the print sheet winding around the platen at the print position. Since a difference opposite to the difference occurs and is canceled out, the deviation between the superposed printing papers during paper feeding becomes small. As a result, it is possible to expect an effect that printing misalignment is eliminated, printing quality is improved, paper jam is eliminated, and reliability is improved.

[Brief description of drawings]

FIG. 1 is a schematic side view of an essential part of a printer to which a paper feeding mechanism according to an embodiment of the present invention is applied.

FIG. 2 is a perspective view of an essential part of the same as shown in FIG.

FIG. 3 is a schematic side view of an essential part of a printer to which a modified example of the paper feeding mechanism of the present invention is applied.

FIG. 4 is a perspective view of a main part of a printer to which a conventional paper feeding mechanism is applied.

FIG. 5 is a schematic side view of the main part shown in FIG.

FIG. 6 is a diagram for explaining interlayer misalignment of copy paper that occurs in a conventional paper feed mechanism.

[Explanation of symbols]

 1 Platen 9 Printing Paper 11 Pin Tractor 23 Guide Rib 23a Projection 27 Discharge Roller 31 First Paper Conveying Path 32 Second Paper Conveying Path

Claims (1)

[Scope of utility model registration request] 1. A first sheet conveying path for guiding a printing sheet sent from the back side of the platen to the front side of the platen and the printing sheet passing through the front side of the platen to the back side of the platen. A first U-shaped paper conveyance path having a second paper conveyance path;
A pin tractor for feeding the print paper into the paper transport path, and a discharge roller for transporting the print paper in the second paper transport path to the rear side, the platen, the pin tractor, and the discharge roller In the paper feed mechanism of the printer for carrying the print paper, the paper carry path portion behind the discharge roller of the second paper carry path is set in a direction opposite to the direction in which the print paper is wound around the platen. A paper feed mechanism for a printer, characterized in that the print paper is bent and guided.