JP3328948B2 - 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 feed mechanism for a printer.

[0002]

2. Description of the Related Art A paper feed mechanism of a printer using a push-type paper feed tractor and a cylindrical platen is disclosed in Japanese Patent Application Laid-Open Publication No. Hei.
What is seen in -8072 is known. As shown in FIG. 11, the portion that performs paper ejection after printing the paper is a cylindrical platen 5 as shown in FIG.
A discharge roller 1 that rotates at a peripheral speed equal to or higher than that of the platen 5 above the platen 5 (hereinafter referred to as a platen), and a continuous sheet 37 discharged above the platen 5 after printing with respect to the discharge roller 1 And a pressing member 2.

[0003]

However, in this method, since the force for pressing the continuous paper 37 against the paper discharge roller 1 is constant, two types of continuous paper 37 (hereinafter referred to as paper) are combined into one paper. As shown in FIG. 4 and FIG.
In the case where push-type paper feed tractors 31, 32 (hereinafter referred to as tractors) are provided at the positions, or the tractors 31, 32 can be selectively attached to and detached from the rear and the front of the platen 5 for use. In this case, if the paper 37 is pressed against the discharge roller 1 with an appropriate force to feed the paper by the tractor 31 behind the platen 5, the paper 37 is fed by the tractor 32 in front of the platen. Sometimes the paper 37 is not strong enough to feed it, causing paper slack,
Also, when the paper 37 is pressed against the discharge roller 1 with an appropriate force to feed the paper 37 by the tractor 32 in front of the platen, the paper 37 is sent when the paper 37 is fed by the tractor 31 behind the platen. There is a problem that the paper is broken due to an excessively strong feeding force, so that accurate and reliable paper feeding cannot be performed. This is because the paper 37 sent out from the tractor 31 behind the platen is wound around the platen 5 and sent, while the tractor 32 in front of the platen is sent.
Is sent without being wound around the platen 5. Therefore, the force acting on the paper 37 is
When the sheet is sent by the tractor 31 at the rear of the platen, the sheet is wound around the platen 5 and is stronger than that when the sheet is sent by the tractor 32 at the front of the platen by the amount of force acting upon rotation of the platen 5.

The present invention has been made in view of such a problem, and has as its object to feed paper 37 from a tractor 31 located behind the platen 5 and a tractor 32 located in front of the platen 5. An object of the present invention is to realize high-precision and reliable paper feeding without causing paper breakage or paper slack in any case when the paper 37 is fed from the printer.

[0005]

That is, a paper feeder for a printer according to the present invention is a paper feeder for a printer in which a tractor for feeding continuous paper is provided at least in two places at the rear and front of a cylindrical platen at least in a detachable manner. In the apparatus, a paper discharge roller which is located above the cylindrical platen and rotates at a peripheral speed equal to or higher than that of the cylindrical platen, and is disposed with a required interval between the paper discharge rollers in the axial longitudinal direction thereof. And a pressing member for pressing the continuous paper against the discharge roller,
When the continuous paper is fed by a tractor disposed behind the cylindrical platen, and when the continuous paper is fed by a tractor disposed in front of the cylindrical platen, the paper discharge roller and the forward
By changing the amount of overlap with the pressing member
Thus, the pressing force of the discharge roller against the continuous paper is changed. Also, when feeding continuous paper by a tractor disposed behind the cylindrical platen, a paper discharge roller and a pressing member are used.
By reducing the amount of overlap between, while reducing the pressing force of the discharge roller, when sending the continuous paper with tractor disposed in front of the cylindrical platen, the discharge path
The overlap between the roller and the pressing member
Accordingly, the pressing force of the paper discharge roller is increased.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic plan view showing a first embodiment using a driven roller 2 which presses a sheet 37 against a sheet discharging roller 1 without pressing against the sheet discharging roller 1, and FIGS. FIGS. 4 and 5 are side views showing the train wheel structure of the first embodiment, and FIGS. 4 and 5 are sectional views taken along the line AA in FIG.
And print head 33, paper guide cover 34, paper guide plate 3
FIG. 5 is a diagram in which a paper holding plate 36 is added.

[0008] A print head 33 is arranged at a fixed minute interval with respect to the platen 5. This print head 33
On the other hand, on the upstream side in the paper feed direction, paper feed tractors 31 and 32 are disposed behind and in front of the platen 5, respectively. The paper 37 sent from the tractor 31 located behind the platen 5 is conveyed between the print head 33 and the platen 5 through the gap between the platen 5 and the paper guide plate 35. The paper 37 sent from the tractor 32 located in front of the platen 5 is provided with a paper guide plate 35 and a paper holding plate 36.
Is conveyed between the print head 33 and the platen 5 through the gap. In the paper discharge section after printing, a paper guide cover 34 for guiding the leading end of the paper 37 between the paper discharge roller 1 and the paper discharge auxiliary roller 2 is arranged above the print head 33. The paper discharge roller 1 is formed of rubber or a material having a high friction coefficient similar to rubber, and is fixed to the paper discharge roller shaft 3 by press fitting or the like so as not to run idle. As shown in FIG. 1, the paper discharge auxiliary roller 2 is positioned on the paper discharge auxiliary roller shaft 4 so as to have an equal distance i on both sides of the paper discharge roller 1. The paper discharge auxiliary roller 2 is structured so as to be able to run idle with respect to the paper discharge auxiliary roller shaft 4.
So that no frictional load is applied to it. The discharge assist roller shaft 4 is attached to an eccentric bearing 6 described later with respect to the frame 9.
Is supported through. A train of gears 11 to 21 is formed outside the frame 9, and the paper feed motor 10, the platen 5, the paper feed tractors 31, 32, and the paper discharge roller shaft 3 are mechanically connected. Further, a switching lever 7 having a cam surface 7a is coaxial with the gear 12 on the outside of the frame 9 and is rotatably attached to the gear 12. A slider 8 having a cam surface 8a is attached to the switching lever 7 so as to swing in conjunction with the switching lever. Switching lever 7
A gear 7b is formed on a part of the gear and is connected to a gear 6a provided on the eccentric bearing 6 of the paper discharge auxiliary roller shaft 4.

Next, the operation of the above components will be described. Tractor 31 located rearward with respect to platen 5
In order to feed the paper 37, the switching lever 7 is at the position shown in FIG. 2, and the gear 13 and the rear tractor driving gear 14 are connected by the cam surface 7a provided on the switching lever 7, and the switching lever 7 The gear 17 is moved in the printing beam direction by a cam surface 8a provided on the slider 8 which swings in synchronization with the tractor driving gear 19 in front. At this time, the paper discharge roller 1 and the paper discharge auxiliary roller 2 are overlapped by h as shown in FIG.
The sheet 37 is brought into contact with the sheet discharging roller 1 by the restoring force of the sheet generated by bending the sheet with the sheet, and the sheet 37 is pulled up by the frictional force generated by this. Here, the outer peripheral speed Vt of the tractor, the outer peripheral speed Vp of the platen, and the outer peripheral speed Ve of the discharge roller are Vt ≦ Vp ≦
It is adjusted so that the relationship Ve is established. Therefore, the force acting on the paper 37 is given by the sum of the paper feeding force of the paper discharge roller 1 and the paper feeding force acting on the rotation of the platen 5 by being wound around the platen 5. Next, when the paper is fed by the paper feed tractor 32 located in front of the platen 5, the switching lever 7 is rotated to the position shown in FIG. Then, the coupling between the gear 13 and the rear tractor drive gear 14 is cut by the cam surface 7a of the switching lever to cut off the drive of the tractor 31 behind the platen, and the gear 17 and the front tractor drive gear 19 are turned by the cam surface 8a of the slider 8. And the tractor 3 in front of the platen
2 so that the driving force is transmitted. Further, an eccentric bearing 6 attached to the paper ejection auxiliary roller shaft 4 so as not to run idle is rotated by a gear 7b provided on the switching lever 7. Since the center of rotation of the eccentric bearing 6 and the center of the discharge assist roller shaft 4 are eccentric, the discharge assist roller shaft 4 moves to the position shown in FIG. At this time, the overlap amount between the paper discharge roller 1 and the paper discharge auxiliary roller 2 becomes H as shown in FIG. Here, the overlap amount H is set to be larger than the overlap amount h shown in FIG. Therefore, the paper feeding force of the paper discharge roller 1 becomes larger than when the paper 37 is fed by the tractor 31 behind the platen, and the paper feeding force acting on the paper 37 by the rotation of the platen 5 by being wound around the platen 5 is corrected. be able to. With this setting, the rear tractor 3
The tension acting on the paper 37 can be made equal between when the paper 37 is sent from 1 and when the paper 37 is sent from the front tractor 32. Therefore, in both the case where the paper 37 is sent from the tractor 31 located behind the platen 5 and the case where the paper 37 is sent from the tractor 32 located in front of the platen 5, there is no high precision without causing the paper tear or the slack. Reliable paper feed can be obtained.

FIG. 6 is a schematic plan view showing a second embodiment in which both the guiding of the paper 37 to the paper discharge roller 1 and the function of pressing the paper 37 against the paper discharge roller 1 are performed using the paper guide cover 34. 7 and 8 are side views showing the train wheel structure of the second embodiment, and FIGS. 9 and 10 are sectional views taken along the line BB in FIG. 6 showing tractors 31, 32, a print head 33, and a paper guide. FIG. 5 is a diagram in which a plate 35 and a paper pressing plate 36 are added.

In the paper guide cover 34, a rib 34a is integrally formed with a single plate 34d connected in the direction of the printing girder. The rib portion 34a is disposed at a distance of i on both sides of the paper discharge roller 1 with overlap amounts h and H with respect to the paper discharge roller 1. Therefore, the structure for applying the discharging force by the bending of the paper 37 is the same as that of the first embodiment. The paper guide cover 34 is fixed to the frame 9 so as to be rotatable around a pin 34b provided at an end thereof. Further, a pin 34c separately provided at an end of the paper guide cover 34 is inserted into a cam groove 7c provided on the switching lever 7, and the paper guide cover 34 is provided.
The position is determined. Other configurations are the same as in the first embodiment.

Next, the operation of the second embodiment will be described.
When the paper 37 is fed by the tractor 31 located rearward with respect to the platen 5, the switching lever 7 is at the position shown in FIG. 7, and the ribs 34a of the paper guide cover and the paper discharge roller 1 are only h as shown in FIG. Overlapping. Next, the tractor 32 located in front of the platen 5
When sending 7, the switching lever 7 is rotated to the position shown in FIG. A pin 34c provided at an end of the paper guide cover 34 is provided with a cam groove 7c provided in the switching lever 7.
10, the paper guide cover 34 rotates and swings about a pin 34 b provided at the end thereof,
It is fixed to the position shown in. At this time, the overlap amount between the rib 34a of the paper guide cover and the paper discharge roller 1 becomes H which is larger than the above-mentioned h as shown in the figure. Therefore,
Functions and effects similar to those of the first embodiment can be obtained.

[0013]

According to the present invention, when the continuous paper is fed by the tractor disposed behind the cylindrical platen, and when the continuous paper is fed by the tractor disposed in front of the cylindrical platen, Overlap between the discharge roller and the pressing member
By changing the amount, the pressing force of the paper discharge roller against the continuous paper is changed, and further, when the continuous paper is fed by a tractor disposed behind the cylindrical platen, the paper is discharged.
Reduce the amount of overlap between the roller and the pressing member.
And while the pressing force of the discharge roller is reduced, when the continuous paper is fed by the tractor disposed in front of the cylindrical platen, the overlap amount between the discharge roller and the pressing member is increased.
By increasing the pressure of the paper discharge roller, the paper is fed from the tractor discharged behind the platen and from the tractor disposed in front of the platen. As a result of equalizing the acting tension, paper tear or paper breakage can occur either when feeding paper from a tractor located behind the platen or when feeding paper from a tractor located in front of the platen. High-precision and reliable paper feeding without sagging.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a first embodiment of the present invention.

FIG. 2 is a side view showing the wheel train structure of the first embodiment.

FIG. 3 is a side view showing the wheel train structure of the first embodiment.

FIG. 4 is a diagram in which tractors 31, 32, a print head 33, a paper guide plate 35, and a paper holding plate 36 are added to a cross-sectional view taken along the line AA in FIG.

FIG. 5 is a diagram in which tractors 31, 32, a print head 33, a paper guide plate 35, and a paper press plate 36 are added to the cross-sectional view taken along the plane AA in FIG.

FIG. 6 is a schematic plan view showing a second embodiment of the present invention.

FIG. 7 is a side view showing the train wheel structure of the second embodiment.

FIG. 8 is a side view showing the wheel train structure of the second embodiment.

FIG. 9 is a diagram in which tractors 31, 32, a print head 33, a paper guide plate 35, and a paper holding plate 36 are added to the cross-sectional view cut along the BB plane in FIG.

FIG. 10 is a sectional view taken along plane BB in FIG. 6, showing tractors 31, 32, print head 33, paper guide plate 35,
FIG. 4 is a diagram in which a paper holding plate 36 is added.

FIG. 11 is a cross-sectional view of a printer showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge roller 2 Discharge auxiliary roller 5 Platen 6 Eccentric bearing 7 Switching lever 10 Paper feed motor 31, 32 Paper feed tractor 33 Print head 34 Paper guide cover

Claims (2)

(57) [Claims] 1. A paper feeder for a printer in which a tractor for feeding continuous paper is provided at least in two positions at a rear and a front of a cylindrical platen so as to be detachable, wherein the paper feeder is located above the cylindrical platen and the cylindrical platen. A discharge roller that rotates at a peripheral speed equal to or higher than that of the discharge roller, and the discharge roller is disposed with a required interval therebetween in the longitudinal direction of the discharge roller, and the continuous paper is supplied to the discharge roller. A pressing member that presses the continuous paper when the continuous paper is fed by the tractor disposed behind the cylindrical platen, and the continuous paper is transmitted by the tractor disposed in front of the cylindrical platen. in the time to send is, before
The overlap amount between the paper ejection roller and the pressing member is changed.
By reduction, the paper feeding device of a printer, characterized in that changing the pressing force of the sheet discharge roller for said continuous paper. 2. The discharge roller when feeding the continuous sheet by the tractor disposed behind the cylindrical platen.
Reducing the amount of overlap between the pressing member and the pressing member
Accordingly, while reducing the pressing force of the sheet discharge roller,
When the continuous paper is fed by the tractor disposed in front of the cylindrical platen, the discharge roller and the pressing unit
2. The paper feeder for a printer according to claim 1 , wherein the pressing force of said discharge roller is increased by increasing the amount of overlap with the material .