JPH10218407A - Automatic paper feeding device in printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate paper sheets by means of a paper carrying roller and to carry (or carry in the backward direction) the paper sheet in a stable manner. SOLUTION: In a part with which a paper feeding roller 14 of a paper sheet mounting part 14 comes in pressure-contact, a friction pad 8 is buried in such a manner that the middle part of the pad 8 in the paper feeding direction is situated on more upper-stream side in the paper feeding direction than a virtual perpendicular penetrating the center of the paper feeding roller 14 toward the surface of the pad 8. In addition, the paper sheet mounting part 7 neighboring on the friction pad 8 is provided with both an inclined surface, which looks out on the downstream side in the paper feeding direction and the upper part of which is projected from the surface of the friction pad 8, and an inclined surface 9B, which looks out on the upper stream side in the paper feeding direction and at least the upper part of which is projected from the surface of the friction pad 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic paper feeder for a printer, and more particularly, to an automatic paper feeder for a printer which separates recording media one by one from a plurality of stacked recording media for recording. .

[0002]

2. Description of the Related Art Generally, a thermal transfer printer, an output device such as a computer, a word processor, a facsimile, etc., is used.
Various printers such as page printers are used.

In order to perform desired recording in such a printer, a plurality of sheets are stored in a sheet placing portion provided in the printer body, and a sheet feed roller is brought into contact with the sheets. By rotating this paper feed roller, the paper stored in the paper mounting portion is separated and conveyed one by one. The paper conveyed by the paper feed roller is conveyed toward a paper feed roller disposed in front of the recording position of the printer, and when the head in the paper feed direction reaches the paper feed roller, the paper is conveyed. It is designed to be taken over by the feed roller.

FIG. 4 is an explanatory view showing a positional relationship between a conventional paper placing section 26 and a paper feed roller 27.

The paper placing portion 26 is formed of a synthetic resin such as plastic, and the coefficient of friction of the paper placing portion 26 formed of the synthetic resin such as plastic is small. As shown in FIG. 4, a plurality of flat rectangular rectangular friction pads 28 made of a material having a high friction coefficient such as cork are provided on a portion of the sheet placing portion 26 facing the supply roller 27. It is buried so as to be positioned slightly above the paper placement section 26 and slightly above it.

In other words, the printer causes the paper feed roller 27 to abut on the uppermost sheet stored in the paper stacking section 26 and to rotate in the paper feeding direction. Is separated from the paper located therebelow. When a plurality of sheets are stacked, the rotational force of the paper feed roller 27 acts only on the uppermost stacked sheet, and the uppermost sheet is separated from the lowermost sheet. At the same time, the lower stacked sheets are subjected to the frictional force acting between the respective stacked sheets and the frictional force acting between the lower surface of the sheet located at the lowest position and the friction pad 28 to the sheet placing portion 26. It will stop. However, the paper placement unit 26
Is made of only plastic or the like, it is not easy to hold the paper placed on the paper placing portion 26 by a frictional force because the material has a small friction coefficient. Therefore, the friction pad 28 compensates for the frictional force acting between the lower surface of the lowermost sheet and the upper surface of the sheet mounting portion 26 formed of a material having a low coefficient of friction such as plastic, so as to compensate for the sheet loading. In order to prevent a sheet to be stopped in the placing section 26 from being conveyed along with the topmost sheet, the sheet is formed of a member having a high coefficient of friction and is embedded in the sheet placing section 26.

As shown in FIG. 4, a paper guide projection 29 having a slope 29B facing the upstream side in the paper feeding direction is provided on the paper mounting portion 26 adjacent to the rear end of the friction pad 28.
Are formed parallel to the rear end of the friction pad 28. In the above-described printer, the sheet stacking section 2 is slid from the upstream side in the sheet feeding direction to the downstream side while the leading edge of the sheet is in contact with the sheet stacking section 26.
6. The paper guide protrusion 29
When the paper is placed, the leading edge of the paper that slides upstream in the paper feeding direction while abutting on the paper mounting portion 26 is moved to the upstream in the paper feeding direction immediately before the portion where the friction pad 28 is provided. The paper sheet is guided upward with a facing slope so as to prevent the leading edge of the paper from being caught on the edge of the friction pad 28 at the boundary between the paper mounting portion 26 and the friction pad 28.

[0008]

However, in the above-described conventional automatic paper feeder for a printer, the friction pad 28 is extremely partially provided for reasons such as limitations on the shape of the printer and cost. Therefore, the rotational force of the supply roller 27 for separating and transporting the sheet and the frictional force generated between the lower-order sheet and the friction pad 28 are superior to the rotational force. , Which is conveyed together with the upper-layer paper, so-called double feed is likely to occur. In particular, when the number of sheets stacked on the sheet placement unit 26 becomes two, the double feed often occurs.

In a conventional printer, the trailing edge is located downstream of the paper guide projection 29 in the paper feeding direction when setting the printing start position of paper or performing color printing of color printing. When the paper sheet is transported in the reverse direction, the trailing edge of the paper sheet abuts on a side surface of the paper guide projection 29 formed perpendicularly to the paper feeding direction side to cause a paper jam, and the reverse transport of the paper sheet is performed. There was a problem that it might interfere.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is an object of the present invention to provide an automatic paper feeder for a printer which can stably separate paper by a paper feed roller and convey and reversely convey the paper. It is intended for.

[0011]

In order to achieve the above object, in an automatic paper feeder of a printer according to the present invention, a friction pad in a paper feed direction is provided at a portion where a paper feed roller of a paper placing section is pressed against. The central portion is buried so as to be located on the upstream side in the paper feeding direction from a virtual perpendicular to the surface of the friction pad from the center of the paper feed roller, and the paper placement portion adjacent to the friction pad is supplied with the paper. A paper guide projection having a slope facing the downstream side in the paper direction and having at least an upper part protruding from the surface of the friction pad and a slope facing the upstream side in the paper feeding direction and having at least an upper part protruding from the surface of the friction pad is protruded. It is characterized by having.

According to a second aspect of the present invention, there is provided an automatic paper feeder for a printer according to the first aspect, wherein the paper mounting portion is detachably provided to the printer. The automatic paper feeder of a printer according to claim 3, wherein the paper mounting portion is formed integrally with the printer. The top surface of the paper feed tray is characterized by:

According to a fourth aspect of the present invention, there is provided an automatic paper feeder for a printer according to any one of the first to third aspects, wherein both slopes of the paper guide projection are provided. It is characterized by being connected at the top with an obtuse angle.

In the automatic paper feeder of these printers according to the present invention, the center of the friction pad in the paper feeding direction is located rearward of the virtual perpendicular to the surface of the friction pad from the center of the paper feed roller. The paper stored in the paper mounting portion is secured so as to secure a greater frictional force acting in a direction in which the paper stops on the paper mounting portion. A paper guide projection having a slope facing the paper feed direction and a slope facing the direction opposite to the paper feeding direction is formed on the paper placement portion adjacent to the rear end side of the friction pad, and is formed on the upper surface of the main body of the paper placement portion. The leading edge of the paper that slides downstream in the paper feeding direction while contacting the sheet is guided to the downstream in the paper feeding direction along the slope formed on the paper guide projection and facing the upstream in the paper feeding direction, and is upstream in the paper feeding direction. The paper sliding to the side 4. The automatic paper feeding of the printer according to claim 2, wherein the leading edge is guided to the upstream side in the paper feeding direction along a slope formed on the paper guide projection and facing the downstream side in the paper feeding direction. The apparatus specifically shows a place where the paper placing section is disposed. In the automatic paper feeder of the printer according to the fourth aspect, the shape of the paper guide protrusion is specifically shown.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an embodiment of a printer to which the automatic paper feeder according to the present invention is applied. The printer 1 of this embodiment is configured to convey a sheet 2 almost horizontally to perform recording. It is configured. The printer 1 has a printer frame 3 disposed inside a printer case (not shown). Below this printer frame 3,
A platen 4 having a flat shape and extending in the width direction of the printer frame 3 is disposed so that its recording surface is directed upward.

A carriage 5 reciprocally movable along a platen 4 by a driving mechanism (not shown) is provided on one side of the printer frame 3. A thermal head (not shown) as a recording head in which the heating elements are arranged in a line is disposed so as to be able to freely contact and separate from the platen 4 by a driving mechanism (not shown). Further, a ribbon cassette (not shown) in which an ink ribbon of a desired color is wound is mounted on the carriage 5 in a detachable manner. The ink ribbon is a heating element portion of the thermal head. And the platen 4. Then, with the paper 2 and the ink ribbon supplied between the platen 4 and the thermal head, the thermal head is pressed against the platen 4, and the pressure contact position between the thermal head and the platen 4 in the head down state is recorded. Position.

A detachable paper cassette 6 is mounted below the printer frame 3 on the upstream side in the paper feeding direction. In this embodiment, the upper surface of the paper cassette 6 has a plurality of sheets. The paper 2 is configured to function as a paper placement unit 7 on which the papers 2 are stacked and placed. As shown in FIG. 2, for example, a plurality of flat rectangular friction pads 8 made of a material such as cork are provided on the paper mounting portion 7 so that the surface thereof is flush with the paper mounting portion 7 and slightly upward. It is buried so that it is located. Friction pad 8 of the present embodiment
Is embedded such that the central portion in the paper feeding direction is located on the upstream side in the paper feeding direction from the position of a virtual perpendicular to the surface of the friction pad 8 from the center of a paper feeding roller described later. A portion adjacent to the rear end of the friction pad 8 has a slope 9A facing the downstream side in the paper feeding direction and a slope 9B facing the upstream side in the paper feeding direction, and has a triangular cross-section connected at each top side. The paper guide projection 9 is formed linearly so as to be parallel to the rear end side of the friction pad 8. The slope 9A facing the downstream side in the sheet feeding direction and the slope 9B facing the upstream side in the sheet feeding direction
It is desirable to expand at an apex angle of 90 degrees or more at the top of FIG. 2, and FIG. 2 shows a case of expanding at an angle of 120 degrees.

A support shaft 10 extending in the width direction of the printer frame 3 and having both ends supported on both sides of the printer frame 3 is provided above the position where the paper placing portion 7 is disposed in the printer 1. This support shaft 1
In the vicinity of the upstream side in the paper feeding direction 0, a paper feed roller drive shaft 11 is disposed in parallel with the support shaft 10. A shaft support hole 1 having an arc shape is provided on both sides of the printer frame 3.
The shaft support hole 12 supports both ends of the feed roller drive shaft 11 in a freely rotatable manner. Further, as shown in FIG. 1, the feed roller drive shaft 11 is connected to the support shaft 10 via a connection arm 13,
By the connecting arm 13, the feed roller driving shaft 11
It is swingable about the support shaft 10 along the shaft support hole 12.

At a position corresponding to the friction pad 8 of the paper placing portion 7 of the paper supply roller drive shaft 11, a plurality of paper supply rollers 14 are mounted so as to have a predetermined interval in the axial direction. The paper feed roller drive shaft 11 is urged in the direction in which the paper placement unit 7 is disposed by an urging member 15 such as a torsion coil spring attached to the support shaft 10.

At this time, in the present embodiment, as described above, the paper feed roller 14 is configured to press the friction pad 8 from the center in the paper feed direction to the downstream side in the paper feed direction. .

A paper feed roller drive shaft 16 extending in the width direction of the printer frame 3 and having both ends supported on both sides of the printer frame 3 is provided upstream of the platen 4 in the paper feeding direction of the printer frame 3. The paper feed roller drive shaft 16 is provided with a plurality of paper feed rollers 17.
Are attached at predetermined intervals. Above each paper feed roller 17, an auxiliary roller 1 is brought into contact with the outer peripheral surface of the paper feed roller 17 and rotated by the paper feed roller 17.
8 is rotatably arranged.

The paper 2 taken out of the paper loading unit 7 by the paper feeding roller 14 is supported between the paper loading roller 7 and the paper feeding roller 17 between the paper loading roller 7 and the paper feeding roller 17 of the printer frame 3. Guide plate 1 for guiding between rollers 18
9 are provided.

Further, the platen 4 of the printer frame 3
A discharge roller drive shaft 21 extending in the width direction of the printer frame 3 and supported by the printer frame 3 is rotatably disposed further downstream in the sheet feeding direction. Is provided with a plurality of paper discharge rollers 22 for discharging the paper 2 on which recording has been completed to the outside at predetermined intervals.

Then, the paper feed roller 14 is moved from the paper
The paper 2 fed by the printer is guided by the guide plate 19 just before the recording position, is delivered to the paper feed roller 17 and the auxiliary roller 18, and is sandwiched between the paper feed roller 17 and the auxiliary roller 18. The sheet 2 after recording is conveyed to a recording position, and is discharged outside the printer 1 by a discharge roller 22.

Next, the operation of the present embodiment when a sheet is placed on the sheet placing section 7 will be described.

First, a plurality of sheets 2 are stacked and placed on the sheet placing section 7. In this case, the sheet 2 is placed on the sheet placing section 7 such that the leading edge of the sheet 2 is slid from the upstream side in the sheet feeding direction to the downstream side while being in contact with the sheet placing section 7. However, at this time, since the paper guide projections 9 are formed in the paper placing portion 7 of the present embodiment, the leading edge of the paper 2 that slides forward while contacting the paper placing portion 7 is formed. Is directly guided upward along the slope 9B facing the upstream in the paper feeding direction formed on the paper guide projection 9 immediately before the embedded portion of the friction pad 8, and the friction pad 8 is With respect to the edge portion, the sheet guide projection 9 moves over without any contact with the force guided upward on the downstream side in the sheet feeding direction, or even if it does so, it contacts from above.
This ensures that the leading edge of the sheet 2 is caught on the edge of the friction pad 8 which is disposed and buried so that the upper surface thereof is flush with or slightly higher than the upper surface of the sheet placing portion 7. It means that it can be prevented. Then, by sliding the leading edge of the sheet 2 again in contact with the sheet placing section 7 downstream in the sheet feeding direction, the sheet 2 is finally placed on the sheet placing section 7. I have.

Next, the recording operation of the automatic sheet feeder of the printer provided with the above-mentioned sheet placement section 7 will be described.

In the recording operation of the printer 1, the power is turned on.
Or a print start command is input to the control means.

In the recording operation, first, an initializing operation is performed. In this initializing operation,
A drive motor (not shown) is driven based on a control command sent from the control means, and the sheet feed roller 14 is held at a small separation position slightly separated from the sheet placement unit 7.

Next, the sheet 2 is fed. In the present embodiment, by driving the drive motor in accordance with a control command from the control means, the paper feed roller 14 held at the small separation position is brought into contact with the upper surface of the paper 2 stacked on the paper mounting portion 7. Contact And the paper feed roller 1
By the rotation of 4, only the uppermost sheet 2 is conveyed in the direction of the sheet feed roller 17.

Here, the operation of the friction pad 8 in the paper placing section 7 will be described.

In this embodiment, the friction pad 8 is
The paper placing unit 7 extends so that the paper supply roller 14 extends upstream from the position where the paper supply roller 14 comes into contact with the paper 2 in the paper supply direction.
Since it is embedded on the upper side, the friction surface between the lower surface of the lowermost sheet 2 of the stacked sheets 2 and the upper surface of the friction pad 8 in the sheet feeding direction from the disposition position of the sheet feed roller 14 It can be formed large on the upstream side. By moving the embedding position of the friction pad 8 to the upstream side in the sheet feeding direction in this way, even when the number of sheets 2 is reduced, the lower sheet 2 has a frictional force with the friction pad 8. As a result, it is possible to stop on the sheet placement unit 7 against the rotational force of the supply roller 14 for conveying the sheet 2 transmitted through the upper sheet 2, and as a result, The rollers 14 convey only the uppermost sheet 2. And the friction pad 8 of this embodiment is
The friction pad 8 having the same shape as the conventional one can be used, and the effect can be improved more than the conventional one without changing the size or the members.

The conveyed sheet 2 is guided by the guide plate 19 just before the recording position and is transferred to the sheet feed roller 17 and the auxiliary roller 18 by continuing to drive the drive motor. At this time, when the leading edge of the paper 2 reaches the contact portion between the paper feed roller 17 and the auxiliary roller 18, the leading edge of the paper 2 abuts on the paper feed roller 17, and the leading edge of the paper 2 is The paper 2 is aligned so as to be parallel to the feed roller 17, and the posture of the paper 2 is controlled.

Next, at the timing when the leading end of the paper 2 is abutted against the paper feed roller 17 and the leading end of the paper 2 is aligned in parallel with the contact portion between the paper feed roller 17 and the auxiliary roller 18, the drive motor is set to a predetermined position. By rotating the paper feed roller 17 and the paper feed roller 14 by the number of steps, the paper 2 is transported between the platen 4 and the thermal head 6. At this point, the leading edge of the paper 2 protrudes from the paper discharge roller 22 side.

Thereafter, by driving the drive motor in the reverse direction by a predetermined number of steps, the paper feed roller 17 is rotated, and the paper 2 is reversely conveyed to the upstream side in the paper feeding direction.
Of the print start position of.

At this time, even if the trailing edge of the paper 2 is located on the paper feed direction side of the paper guide projection 9 of the friction pad 8,
At the time of reverse conveyance, the trailing edge of the sheet 2 comes into contact with a slope 9 </ b> A facing the downstream side in the sheet feeding direction of the sheet 2 formed on the sheet guide protrusion 9 formed on the sheet placing portion 7,
Since the trailing edge can be guided to the opposite side in the sheet feeding direction along the shape of the slope, it is possible to prevent a paper jam at the friction pad 8 portion.

Then, predetermined recording is started in a state where the recording start position is located in this manner. That is,
The thermal head 6 is pressed against the platen 4 via the ink ribbon and the paper 2 and the heating element of the thermal head 6 is selectively driven based on a desired recording signal while moving the carriage 5 along the platen 4. Thus, desired recording is performed on the paper 2.

When the paper 2 is conveyed during the recording, the driving motor is driven to rotate forward to rotate the paper feed roller 17 in the paper feeding direction. Thereafter, the paper feed roller 17 repeats the paper feed accompanying the line feed operation required for recording.

When the recording on the paper 2 is completed in this way, the drive motor is driven to rotate normally and the paper discharge roller 22 is rotated to discharge the paper 2 so that one paper 2 is discharged. All the recording operations for are ended.

When printing is to be performed on the next sheet 2, recording can be sequentially performed on the sheet 2 by repeating the above operation.

FIG. 3 shows a second embodiment of the printer 1 to which the automatic paper feeder according to the present invention is applied. Hereinafter, the configuration of the printer 1 according to the second embodiment will be briefly described.

The printer 1 according to the present embodiment is configured to convey the paper 2 almost vertically to perform recording. Therefore, in the printer 1, a platen 4 having a flat plate shape and extending in the width direction of the printer frame 3 is disposed so that its recording surface is substantially vertical. Also,
On one side of the printer frame 3, there is provided a carriage 5 which is reciprocally movable along a platen 4 by a drive mechanism (not shown). At the lower end of the carriage 5, a plurality of heating elements (not shown) are provided. A thermal head 23 as a recording head in which are arranged in a line is disposed so as to be able to freely contact and separate from the platen 4 by a driving mechanism (not shown). A ribbon cassette is removably mounted on the carriage 5.
The thermal head is pressed against the platen 4 in a state where the paper 2 and the ink ribbon stored in the ribbon cassette are supplied between the thermal head and the thermal head. The position is the recording position.

At substantially the center of the printer frame 3, there is provided a feed roller driving shaft 11 extending in the width direction of the printer frame 3 and having both ends supported on both sides of the printer frame 3. ing. A plurality of feed rollers 14 are attached to the feed roller drive shaft 11 so as to have a predetermined interval in the axial direction.

A paper feed tray support shaft 24 is disposed above the printer frame 3 on the upstream side in the paper feed direction. A sheet tray 25 configured to function as the sheet stacking unit 7 on which the sheets 2 are stacked is mounted so as to be swingable, and the sheet tray 25 is swung in the sheet feeding direction. In the state, the front of the paper loading section 7 is
4 can be pressed.

A plurality of friction pads 8 made of a material such as cork are provided on the paper placing portion 7 so that the surfaces thereof are positioned slightly above the paper placing portion 7 and in the paper feeding direction. The central portion is buried such that a virtual perpendicular line from the center of the paper feed roller 14 to the surface of the friction pad 8 is located downstream in the paper feed direction from a corresponding position. A slope 9A facing the downstream side in the paper feeding direction of the paper 2 and a slope 9B facing the upstream side in the paper feeding direction are provided on the upper surface of the paper placing section 7 adjacent to the rear end side of the friction pad 8. Paper guide projection 9 having a triangular cross section
Are formed linearly so as to be parallel to the rear end side of the friction pad 8.

Then, below the paper feed roller 14,
The leading edge of the paper 2 placed on the paper placement unit 7 abuts, and the separation plate 20 for separating only the topmost paper 2 among the stacked papers 2 is inclined at a predetermined angle. It is arranged as follows.

Further, below the platen 4 of the printer frame 3 and obliquely above the paper feed roller drive shaft 11,
A paper feed roller drive shaft 16 extending in the width direction of the printer frame 3 and having both ends supported on both sides of the printer frame 3 is provided.
6, a plurality of paper feed rollers 17 are attached at predetermined intervals. An auxiliary roller 18 is rotatably disposed below and beside each of the paper feed rollers 17 and is in contact with the outer peripheral surface of the paper feed roller 17 and is rotated by the paper feed roller 17. A paper feed roller 14 is provided between the paper loading section 7 and the paper feed roller 17.
A guide plate 19 having a curved surface is provided to guide the sheet 2 taken out from the sheet stacking section 7 between the sheet feed roller 17 and the auxiliary roller 18 located on the downstream side in the sheet feeding direction. .

Further, the platen 4 of the printer frame 3
A discharge roller drive shaft 21 extending in the width direction of the printer frame 3 and supported by the printer frame 3 is rotatably disposed further downstream in the sheet feeding direction. Is provided with a plurality of paper discharge rollers 22 for discharging the paper 2 on which recording has been completed to the outside at predetermined intervals.

Then, the paper feed roller 14 is moved from the paper
The paper 2 fed by the printer is guided by the guide plate 19 just before the recording position, is delivered to the paper feed roller 17 and the auxiliary roller 18, and is sandwiched between the paper feed roller 17 and the auxiliary roller 18. The recording paper 2 is conveyed to a recording position located above the recording paper 2, and the recorded paper 2 is discharged to the outside of the printer 1 by the discharge rollers 22.

In the automatic paper feeder of the printer constructed as described above, the arrangement side of the friction pad 8 of the paper feed tray 25 is swung in a direction away from the platen 4 by a control means (not shown). The upper edge of the paper loading unit 7 is positioned from above with respect to the paper loading unit 7 of the paper supply tray 25 in a state where the friction pad 8 and the paper supply roller 14 are released from contact with each other. While sliding, the sheet is placed on the sheet placing section 7 of the present embodiment. At this time, since the paper guide projections 9 are formed on the upper surface of the paper mounting portion 7, the leading edge of the paper 2 is
Immediately before the embedded portion of the friction pad 8, the leading edge of the sheet 2 is guided to the downstream side in the sheet feeding direction along the slope 9 </ b> B facing the upstream side in the sheet feeding direction formed on the sheet guide projection 9. It is possible to prevent the friction pad 8 from being caught on the end.

Then, according to a control command from the control means,
Again, the paper feed tray 25 is swung in the direction in which the friction pad 8 is disposed closer to the platen 4 to bring the friction pad 8 into contact with the paper feed roller 14.
The printer 1 starts the automatic paper feeding and recording operation, and conveys only the uppermost paper 2 in the direction of the paper feed roller 17 by the rotation of the paper feed roller 14. The operation of the friction pad 8 at this time is the same as that of the above-described embodiment, and the description is omitted.

Then, the conveyed sheet 2 is guided by a guide plate 19 and is transferred to a sheet feed roller 17 and an auxiliary roller 18 by continuing to drive the drive motor, and is transferred to the sheet feed roller 17. The leading edge of the paper 2 is directed vertically upward from the paper feed roller 17 by the auxiliary roller 18 disposed beside the paper feed roller. Then, by driving the drive motor by a predetermined number of steps, the paper feed roller 17 and the paper feed roller 14 are rotated, and after the paper 2 is conveyed between the platen 4 and the thermal head 6, By driving the drive motor in the reverse direction by a predetermined number of steps, the paper feed roller 17 is rotated in the reverse direction to reversely convey the paper 2 to the upstream side in the paper feeding direction, and to find the print start position of the paper 2. This point is not different from the first embodiment. Also in the present embodiment, at the time of the reverse conveyance, the trailing edge of the sheet 2 comes into contact with the slope 9A facing the downstream side of the sheet guide projection 9 in the sheet feeding direction, so that the trailing edge of the sheet 2 is adjusted to the slope. Since the paper can be guided to the upstream side in the paper feeding direction according to the shape, it is possible to prevent paper jam at the friction pad 8 portion.

After the recording start position is located in this manner, the thermal head 6 is pressed against the platen 4 via the ink ribbon and the paper 2 to move the carriage 5 along the platen 4. By selectively driving the heating elements of the thermal head 6 based on a desired recording signal, desired recording is performed on the paper 2.

The present invention is not limited to the above-described embodiment, but can be variously modified as needed. For example, the paper guide protrusion is not limited to the above-described shape.For example, a convex paper guide protrusion having a slope facing the downstream side in the paper supply direction and a slope facing the upstream side in the paper supply direction, The ridge line to be connected may be formed so as to be dotted so as to be parallel to the rear end side of the friction pad.

[0056]

As described above, the automatic paper feeder of the printer according to the present invention increases the frictional force acting in the direction in which the paper stored in the paper mounting portion stops on the paper mounting portion. As a result, the probability of occurrence of double feed can be significantly reduced, the paper can be separated by the paper feed roller in a stable manner, and the slope formed on the paper guide projection 9 allows the paper to be separated. When the paper is transported in the paper feeding direction, the leading edge of the paper is prevented from being caught by the friction pad when the paper is transported in the reverse direction, and the transport and reverse transport of the paper are stabilized. In addition, these improvements have an effect that they can be made at a low cost with a simple design change.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of an automatic paper feeder of a printer according to the present invention.

FIG. 2 is an enlarged side view of a main part of the automatic sheet feeding device of FIG. 1;

FIG. 3 is a schematic side view showing another embodiment of the automatic sheet feeder of the printer according to the present invention.

FIG. 4 is an enlarged side view of a main part of a conventional automatic paper feeder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 2 Paper 3 Printer frame 4 Platen 5 Carriage 6 Paper feed cassette 7 Paper loading part 8 Friction pad 9 Paper guide protrusion 9A Slope facing downstream in the paper feeding direction 9B Slope facing upstream in the paper feeding direction 10 Support shaft 11 Feeding Paper roller drive shaft 12 Shaft support hole 13 Connecting arm 14 Paper feed roller 15 Biasing member 16 Paper feed roller drive shaft 17 Paper feed roller 18 Auxiliary roller 19 Guide plate 20 Separator plate 21 Discharge roller drive shaft 22 Discharge roller 23 Thermal Head 24 Paper tray support shaft 25 Paper tray

Claims (4)

[Claims] 1. A sheet stacking section capable of stacking and storing sheets to be provided for recording, and a sheet stored in the sheet stacking section, which can be brought into contact with the sheet stack, and the sheets are separated and conveyed one by one. An automatic paper feeder for a printer having a paper feed roller that performs the following operations. It is buried so as to be located on the upstream side in the paper feeding direction from a virtual perpendicular to the surface of the friction pad from the center, and the paper placement portion adjacent to the friction pad is located at least at the upper portion facing the downstream side in the paper feeding direction. A paper guide projection having a slope protruding from the surface of the friction pad and a slope protruding at least in an upper portion protruding from the surface of the friction pad on the upstream side in the paper feeding direction. Automatic Paper feeder. 2. The automatic sheet feeding device according to claim 1, wherein the sheet placing portion is an upper surface of a sheet feeding cassette detachably provided in the printer. 3. The automatic sheet feeding device according to claim 1, wherein the sheet placing portion is an upper surface of a sheet feeding tray formed integrally with the printer. 4. The automatic paper feeder of a printer according to claim 1, wherein both slopes of the paper guide protrusion are connected at an apex at an obtuse angle.