JP3287516B2 - Printer paper feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for a printer, and more particularly to a paper feeder for a printer capable of feeding paper with high accuracy.

[0002]

2. Description of the Related Art Conventionally, printers that perform desired printing on paper by driving a printing head based on a desired printing signal have been widely used.

FIG. 3 shows such a conventional general printer. A plate-like platen 2 is disposed substantially at the center of a frame 1 of the printer so that its printing surface is substantially vertical. A carriage shaft 3 is arranged below the front side of the platen 2 of the frame 1 in parallel with the platen 2. A flange-shaped guide portion 4 is formed at the front edge of the frame 1. A carriage 5 reciprocates along the carriage shaft 3 and the guide portion 4 on the carriage shaft 3 and the guide portion 4. It is movably mounted. The leading end of the carriage 5 faces the platen 2,
A print head 6 which is movable to and away from the platen 2 by a drive mechanism (not shown) is attached. An ink ribbon is housed inside the carriage 5 on the upper surface thereof. And platen 2
And a ribbon cassette (not shown) that guides between them. Further, on the upper surface of the carriage 5, a take-up bobbin 7 for taking up the ink ribbon of the ribbon cassette and a delivery bobbin 8 for sending out the ink ribbon are provided respectively.

A paper insertion port 9 for feeding paper (not shown) to the front of the platen 2 is formed behind the platen 2, and the paper insertion port 9 is formed at a predetermined speed in the paper insertion port 9. A paper feed roller 10 for transporting the paper is provided. Below the paper feed roller 10, a pressure roller 11 that is pressed against the paper feed roller 10 is rotatably disposed, and is mounted on one side of the frame coaxially with the paper feed roller 10. The paper feed gear 12 is arranged to protrude. The paper feed gear 12 has a motor gear 1 of a paper feed motor 14 via a plurality of transmission gears 13.
5 is connected, and the paper feed motor 14 is driven to rotate the paper feed roller 10 via the motor gear 15, each transmission gear 13 and the paper feed gear 12, respectively. Paper feed roller 10
The paper inserted between the roller and the pressure roller 11 is nipped and conveyed.

In the conventional printer, paper is inserted from the paper insertion slot 9, the paper is sandwiched between the paper feed roller 10 and the pressing roller 11, and the paper feed roller 10 is driven by a paper feed motor 14. By rotating the sheet, the sheet is transported at a predetermined speed in a direction orthogonal to the moving direction of the carriage 5. On the other hand, while the print head 6 is pressed against the paper with a predetermined pressing force, the carriage 5 is moved, and the winding bobbin 7 is rotated to wind the ink ribbon of the ribbon cassette. By driving the print head 6 based on a desired print signal, desired printing is performed on the paper.

[0006]

However, in such a conventional printer, when paper is fed,
According to the rotation of the paper feed motor 14, the paper feed roller 10 can be driven to rotate by a predetermined one line feed pitch,
Motor gear 15, each transmission gear 13, and paper feed gear 12
Is set to a predetermined gear ratio.
When the paper feed motor 14 is driven to rotate the motor gear 15 to drive the paper feed rotor by one line feed pitch from the state shown in FIG. 4A, as shown in FIG. 15, since the rotation amounts of the transmission gears 13 and the paper feed gear 12 are different from each other, even if the motor gear 15 is rotationally driven with high precision by the paper feed motor 14, the motor gear 15, the transmission gears 13, and the paper Due to the dimensional accuracy and meshing error of the feed gear 12, a rotation error of the paper feed gear 12 becomes large, and there is a problem that the paper feed accuracy of the paper feed roller 10 is remarkably reduced.

Therefore, in order to drive the paper feed roller 10 with high precision, the motor gear 15 and the transmission gears 13 are required.
In addition, it is necessary to manufacture all the paper feed gears 12 with high accuracy, but it is extremely difficult in practice, and it has been extremely difficult to increase the paper feed accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and enables the paper feed roller to be driven to rotate with high precision even when there is a dimensional error of the transmission gear, and to perform paper feed with extremely high precision. It is an object of the present invention to provide a paper feeder for a printer that can perform the following.

[0009]

According to a first aspect of the present invention, there is provided a paper feeder for a printer in which a paper feed roller for transporting a predetermined paper at a predetermined print position of the printer is rotatably provided. A paper feed gear for rotating the paper feed roller and a motor gear for rotating the paper feed motor via at least one transmission gear;
In the paper feed device of the printer, the outer peripheral length of the paper feed roller is set to a length corresponding to N line feed pitch, and the gear ratio of the motor gear, the transmission gear and the paper feed gear is set to the paper feed roller. 1 of the outer circumference of the paper feed roller
/ N (except when 1 / N is an integer) , the gear ratio is set so that the transmission gear always stops at the rotation start position when it is driven to rotate by the line feed pitch. Is what you do.

Preferably, the paper feed roller is provided with a detector for indicating a reference position of the paper feed roller, and a detector for detecting the detector and outputting a detection signal is provided. And a control device for driving and controlling the paper feed motor so that the paper feed roller is always positioned at the reference position when paper feed is started upon input of a detection signal from the control unit.

[0011]

According to the paper feeding device of the printer according to the present invention,
At the start of the paper feed, the paper feed motor is driven to rotate the paper feed roller via the motor gear, each transmission gear and the paper feed gear, and the detection unit detects the detection marker of the paper feed roller. The paper feed motor is stopped by the control device based on the signal, and after the paper feed roller is positioned at the reference position, by driving the paper feed motor, the paper feed gear is transmitted via the motor gear and each transmission gear. The paper is driven to rotate, whereby the paper feed roller is rotated to convey the paper by a predetermined amount to perform a line feed. In this case, the gear ratio of each transmission gear is
When the paper feed roller is driven to rotate by 1 / N line feed pitch, the transmission gears are set to always stop at the rotation start position. Each transmission gear always rotates an integer, and therefore, when the rotation of the motor gear is transmitted to the paper feed gear, even if there is a dimensional accuracy error, a meshing error, or the like of each transmission gear, the influence of this error is reduced. The paper feed roller is always positioned at the reference position at the start of paper feed, so that when the paper feed roller rotates, the paper feed Since the rotational position of the roller is always moved to a fixed position, even if a dimensional error such as eccentricity occurs on the outer peripheral surface of the paper feed roller, paper feeding is performed with the error amount being constant. One in which it is bet.

[0012]

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

FIGS. 1 and 2 show an embodiment of a paper feeder of a printer according to the present invention. A cylindrical paper feed roller 10 which also functions as a platen of the printer is rotatably disposed. A carriage (not shown) to which a predetermined print head is attached is disposed in front of the paper feed roller 10 so as to reciprocate along the paper feed roller 10.

The rotary shaft 16 of the paper feed roller 10
A paper feed gear 12 is coaxially mounted on one end of the paper feed motor. A paper feed motor 14 such as a stepping motor for rotating the paper feed roller 10 is arranged near the paper feed gear 12. Has been established. This paper feed motor 1
A motor gear 15 is fixed to the shaft 17 of the fourth gear 4. The motor gear 15 and the paper feed gear 12 are formed coaxially with a large gear portion 18 formed on the outer peripheral portion and the large gear portion 18. The small gear portion 19 is connected by a first transmission gear 13a, a second transmission gear 13b, and a third transmission gear 13c formed respectively. The motor gear 15 is connected to the large gear portion 18a of the first transmission gear 13a.
The small gear portion 19a of the first transmission gear 13a is
3b, the small gear 19b of the second transmission gear 13b meshes with the large gear 18c of the third transmission gear 13c, and the small gear 19c of the third transmission gear 13c meshes with the paper feed gear 12, respectively. Thereby, each transmission gear 13
By means of a, 13b and 13c, the rotation of the paper feed motor 14 is transmitted to the paper feed gear 12 while being reduced.

In this embodiment, the gear ratio of the transmission gears 13a, 13b, 13c is such that the transmission gears 13a, 13b, 13c are rotated when the paper feed roller 10 is rotated by one line feed pitch. 13c is set to a gear ratio that always stops at the rotation start position.

For example, when performing a constant pitch feed in which one line feed pitch is 10.16 mm, the paper feed motor 14
Resolution of 18 °, paper feed resolution of 2400 dpi,
When the outer circumference of the paper feed roller 10 is set to 50.8 mm and the paper feed roller 10 is rotated once to feed the paper for five line feed pitches, the motor gear 1
5, each transmission gear 13a, 13b, 13c, paper feed gear 1
The gear ratio of 2 is set to 3: 4: 4: 5. Specifically, assuming that the number of teeth of the motor gear 15 is 14, the number of teeth of the large gear portion 18a of the first transmission gear 13a is 42, and the number of small gear portions 1 is 1.
The number of teeth 9a is 14 and the large gear portion 1 of the second transmission gear 13b
56 teeth for 8b, 14 teeth for small gear 19b,
The number of teeth of the large gear portion 18c of the third transmission gear 13c is 56,
The number of teeth of the small gear portion 19c may be set to 14 and the number of teeth of the paper feed gear 12 may be set to 70.

Further, a detection marker 20 as a detecting portion is formed on an outer peripheral portion of one end face of the paper feed roller 10, and a detection marker for detecting the detection marker 20 is provided near the end face of the paper feed roller 10. A vessel 21 is provided.
Further, a control device (not shown) for inputting a detection signal from the detector 21 to drive and control the paper feed motor 14 is provided, and the control device detects the detection marker 20 by the detector 21. Position the paper feed roller 1
The reference position is set to 0, and control is performed so that paper feeding always starts from this reference position.

Next, the operation of the present embodiment will be described.

First, when desired printing is performed, the paper feed motor 14 is driven to rotate the paper feed roller 10 via the motor gear 15, the transmission gears 13a, 13b, 13c and the paper feed gear 12. When the detection marker 20 of the paper feed roller 10 is detected by the detector 21,
Based on this detection signal, the control device controls the paper feed motor 1
4 is stopped, and the paper feed roller 10 is positioned at the reference position.

Then, the paper is inserted into a portion to be joined to the paper feed roller 10 and the paper feed motor 14 is driven, so that the motor gear 15 and the transmission gears 13a,
The paper feed gear 12 is rotationally driven via 13b and 13c, whereby the paper feed roller 10 is rotated to convey the paper by a predetermined amount and perform a line feed. Then, the print head is driven based on a desired print signal while driving the carriage, thereby performing desired printing on the paper.

In this case, in the present embodiment, when the gear ratio of each of the transmission gears 13a, 13b, and 13c is changed by rotating the paper feed roller 10 by one line feed pitch,
Since the transmission gears 13a, 13b, and 13c are set to always stop at the rotation start position, when the rotation of the motor gear 15 is started from the state shown in FIG. As shown in FIG. 2B, the transmission gears 13a, 13b, 13c always rotate an integer. Therefore, the motor gear 1
When the rotation of No. 5 is transmitted to the paper feed gear 12, even if there is a dimensional accuracy error or a meshing error of each of the transmission gears 13a, 13b, 13c, the influence of this error is eliminated, and the paper feed accuracy is reduced. Can be significantly increased. And
The stop position accuracy of the paper feed gear 12 that determines the final paper feed accuracy is determined only by the accuracy of the paper feed gear 12, and the paper feed accuracy is improved only by improving the accuracy of the paper feed gear 12. It is possible to increase.

For example, according to the above-described specific example, when paper is fed at one line feed pitch, a driving pulse of 960 pulses is applied to the paper feed motor 14, and the resolution of the paper feed motor 14 becomes 18 °. Therefore, the paper feed motor 14 is driven to rotate 48 times. The rotation of the paper feed motor 14 drives the motor gear 15 to rotate, so that the motor gear 15, the transmission gears 13 a,
13b, 13c, the gear ratio of the paper feed gear 12 is 3: 4:
Since the ratio is set to 4: 5, the rotation of the motor gear 15 drives the first transmission gear 13a 16 rotations, the second transmission gear 13b 4 rotations, and the third transmission gear 13c one rotation. The gear 12 is driven by １ ／ rotation. At this time, since the outer circumference of the paper feed roller 10 is formed to 50.8 mm, it is 10.16 m
Paper can be fed at a line feed pitch of m minutes.

Therefore, in the present embodiment, when the gear ratio of each of the transmission gears 13a, 13b, 13c is set such that the paper feed roller 10 is driven to rotate by one line feed pitch,
Since the transmission gears 13 are set so as to always stop at the rotation start position, when the rotation of the motor gear 15 is transmitted to the paper feed gear 12, a dimensional accuracy error, a meshing error, etc. As a result, the accuracy of paper feed by the paper feed roller 10 can be significantly increased, and it is not necessary to increase the dimensional accuracy of the transmission gear 13 and the like to the utmost.

The detector 21 detects the marker 2
0 is detected and the paper feed roller 10 is positioned at the reference position by the control device, and the paper feed is always started from this reference position. The rotational position of the paper feed roller 10 is always moved to a fixed position, and even if a dimensional error such as eccentricity occurs on the outer peripheral surface of the paper feed roller 10, the paper can be fed with the error amount being constant. .

The present invention is not limited to the above-described embodiment, but can be variously modified as needed.

[0026]

As described above, in the paper feeder of the printer according to the present invention, when the gear ratio of each transmission gear is driven to rotate the paper feed roller by 1 / N line feed pitch, each transmission gear is rotated. Since it is set to always stop at the rotation start position, when the rotation of the motor gear is transmitted to the paper feed gear,
It is not affected by the dimensional accuracy error and the meshing error of each transmission gear. As a result, the paper feeding accuracy by the paper feed roller can be significantly increased, and the dimensional accuracy of the transmission gear and the like does not need to be increased to the utmost. In addition, since the paper feed roller is always positioned at the reference position at the start of paper feed, when the paper feed roller rotates, the rotational position of the paper feed roller is always moved to a fixed position. Even when a dimensional error such as eccentricity occurs on the outer peripheral surface of the paper feed roller, the paper feed can be performed with the error amount being constant.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a part of an embodiment of a paper feeding device of a printer according to the present invention.

FIG. 2A is an explanatory diagram showing a state of starting paper feeding of each gear according to the present invention, and FIG. 2B is an explanatory diagram showing a state of finishing paper feeding of each gear according to the present invention.

FIG. 3 is a perspective view showing a conventional general printer.

FIG. 4A is an explanatory diagram showing a state in which the paper feed of each gear by the conventional paper feed device is started, and FIG. 4B is an explanatory diagram showing a state in which the paper feed of each gear is completed by the conventional paper feed device. Figure

[Explanation of symbols]

 Reference Signs List 10 paper feed roller 12 paper feed gear 13 transmission gear 14 paper feed motor 15 motor gear 20 detection marker 21 detector

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-154959 (JP, A) JP-A-5-104787 (JP, A) JP-A-1-288457 (JP, A) 124266 (JP, A) Hikaru 1-11-1939 (JP, U)

Claims (2)

(57) [Claims] A paper feed roller that conveys predetermined paper at a predetermined print position of a printer is rotatably disposed, a paper feed gear that rotationally drives the paper feed roller, and a paper feed motor that is rotationally driven by a paper feed motor. that in the paper feeding device of a printer comprising connected via at least one transmission gear and motor gear, set the outer peripheral length of the paper feed roller to the length of the N line feed pitch, the motor gear, transmission gear and paper Regarding the gear ratio of the feed gear, the paper feed roller is set to 1 / N of the outer peripheral length of the paper feed roller (where 1 / N
Wherein the gear ratio is set such that the transmission gear always stops at the rotation start position when the rotation is driven by the line feed pitch ( excluding the case where is an integer) . 2. A paper feed roller, comprising: a detector for indicating a reference position of the paper feed roller; and a detector for detecting the detector and outputting a detection signal. 2. A printer according to claim 1, further comprising a control device for driving and controlling said paper feed motor so that said paper feed roller is always positioned at said reference position when a signal is input to start paper feed. Paper feeder.