JP2585709Y2 - Printer output mechanism - 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 discharge mechanism of a printer.

[0002]

2. Description of the Related Art The prior art is disclosed in Japanese Patent Laid-Open No. 1-8072.
2. Description of the Related Art There is known a paper feed mechanism of a printer as shown in FIG. FIGS. 8 to 10 show a conventional embodiment close to the contents disclosed therein. FIG. 8 is a front view of a conventional paper discharge mechanism, and FIG. 9 is a cross-sectional view of a cross-section CC thereof. Here, a description will be given of a paper discharge mechanism of a device capable of printing 136 digits of alphabets. Fan hold paper 57 which is a paper in FIG.
Is sent by a tractor 52, wound around a platen 53, printed by a print head 54, and sent to a paper discharge mechanism 55. The paper discharge mechanism 55 includes a paper discharge roller unit 59 composed of a paper discharge roller 50, a paper discharge roller shaft 51, and a gear 64 serving as a power transmission means, a paper discharge cover 56, a paper discharge plate 60, and the like. The fixing unit includes fixing means for fixing the paper roller unit 59, the discharge cover 56, and the discharge plate 60, and holding means for rotatably holding the discharge roller unit 59. The rib portion 56b of the discharge cover 56 and the discharge roller unit 59 are configured such that their relative positions do not change even when the discharge roller unit 59 rotates. The paper discharge cover 56 is fixed to the frame 62 by screws 63 as fixing means. The discharge roller unit 59 is rotatably held by a frame 62 having a bearing function, and the movement of the discharge roller shaft 51 in the longitudinal direction is restricted. A paper discharge roller 50 made of rubber or a material having a similar high friction coefficient provided for pulling the paper is fixed to the paper discharge roller shaft 51 by fixing means such as press-fit so as not to run idle. The paper discharge rollers 50 commonly use parts having the same shape. The gear 64 is also fixed to the discharge roller shaft 51. The sheet discharge cover 56 has a single plate portion 56a connected to the column direction, and a rib portion 56b for guiding the sheet at the ridge line portion is formed in an integrated structure. The portion 56a extends to the lowest position, and the rib portion 56b also extends to the same position. The pressurizing mechanism includes a discharge cover 56 and a discharge roller unit 59 . When the leading edge of the sheet is fed from the front of the print head 54, the sheet is guided along the rib 56b of the sheet ejection cover 56, and the sheet enters between the rib 56b and the sheet ejection roller 50. As shown in FIG. 8, the rib portion 56b and the paper discharge roller 50 are arranged with a gap of L on both sides of the paper discharge roller 50 with an overlap amount of M as shown in FIG. The force that presses the sheet against the discharge roller 50 is determined by the gap L, the overlap amount M, and the spring property of the sheet. The paper discharge force due to the friction of the paper is determined by the dynamic friction coefficient when the paper discharge roller 50 is in contact with the paper and rotating, and the pressing force. Hereinafter, this is referred to as a sheet discharging force. When the paper discharge roller is stopped and printing is being performed, the paper tends to return to its original flat shape due to its spring property. The upstream side of the sheet is fixed because it is positioned by the tractor 52, and the sheet on the downstream side attempts to return to the upstream side. That is, the sheet contained in the sheet discharging mechanism 55 is pulled back to the platen 53 side, and sags around the platen 53. This force for returning the sheet is called a sheet return force. When the sheet is pulled back, the force for pressing the sheet against the discharge roller 50 (the same as the force for pressing the sheet against the rib portion 56b) and the sheet and the rib portion 5
The first static friction force, which is the product of the static friction coefficients between the sheets 6b, the force that presses the sheet against the paper ejection roller 50, and the second static friction force, which is the product of the static friction coefficient between the sheet and the paper ejection roller 50, acts.
The friction force obtained by adding the first static friction force and the second static friction force is called a static friction force.

FIG. 10 is a cross-sectional view taken along the line DD in FIG. 8, and the contact length V between the rib portion 56b and the sheet is shown in FIG.
It is shorter than the C section. As shown in FIG. 8, the plate portion 56a of the paper ejection cover 56 is raised upward as it goes to a digit side smaller than about the 40th digit, and the plate portion 56a is raised upward as it goes to a larger digit side. In this method, a wide sheet is guided between the discharge cover 56 and the discharge plate 60 at the 40th digit at the beginning, and the sheet is gradually discharged at the digit side smaller than the 40 digit and the larger digit side as the sheet is fed downstream. This is for guiding between the paper cover 56 and the paper discharge plate 60. The plate portion 56a and the rib portion 56 of the discharge cover 56
The reason why b extends to the lowest position in the 40th digit is to guide the sheet between the discharge cover 56 and the discharge plate 60 even when a narrow sheet is used. The sheet discharge force of the sheet is affected by the contact length V between the rib portion 56b in the sheet traveling direction and the fan hold sheet 57 as the sheet, as well as the gap L. Contact length V
When the length is long, the paper is easily restrained, which has the effect of apparently increasing the spring property of the paper. When the contact length V is short, the degree of freedom of the sheet is increased and the effect of apparently reducing the spring property of the sheet is obtained. The paper ejection force on the small girder side increases because the contact length V is long,
The paper ejection force on the large girder side is small because the contact length V is short. Regarding the static friction force in the running direction of the paper,
When the contact length V with the contact 6b is long, the static friction force increases, and when the contact length V is short, the static friction force decreases. The static frictional force on the small girder side increases because the contact length V is long, and the static frictional force on the large girder side decreases because the contact length V is short. 40
In the vicinity of the digit, the spring property of the paper increases, and the paper and the discharge roller 50
As the vertical drag between the plates increases, the paper ejection force, which is the product of the vertical drag and the kinetic friction coefficient, is large, and the paper is reliably fed.The large static friction force causes the paper to return around the platen and lift the paper off the platen. Preventing.

[0004]

As described above, the conventional paper discharge using the all-jagged paper discharge roller 50 and changing the width of the plate portion 56a and the rib portion 56b of the paper discharge cover 56 according to the position of the girder. In the mechanism 55, the sheet ejection force and the static friction force are unbalanced on the side of the small girder and the side of the large girder. When the sheet is pulled unbalanced by the sheet ejection force, the sheet is skewed and wound around the platen 53, so that the large girder side As a result, the paper floats from the platen 53, and the static frictional force is unbalanced, so that the paper float is promoted, and the paper further floats from the platen 53 on the large girder side. When the floating portion of the sheet is hit with the wire of the head 54, the sheet vibrates in a large area in accordance with the amount of the sheet floating, generating large noise.

[0005]

The paper discharge mechanism of the printer according to the present invention covers the paper discharge roller on the lower side of the platen in the paper transport direction so that the portion for guiding the paper is long in the paper discharge direction. In the paper ejection mechanism of the printer provided with a short paper ejection cover in the portion, the paper guiding force between the paper ejection roller and the overlap member provided in the paper ejection cover is used in the portion for guiding the paper. Means are provided to reduce the static friction force and increase the other portions. In the above-described paper guiding portion, a paper discharge roller having a knurled peripheral surface is provided integrally with a common discharge shaft in other portions. Further, in the sheet guiding portion, the axial distance between the sheet discharging roller and the overlap member is widened, and in other portions, the space is narrowed . In addition, while the respective overlapping members are formed at regular intervals, the paper discharge rollers disposed between the respective overlapping members are formed to be short in the axial direction in the paper guiding portion and long in other portions. Things. In addition, as the overlap member, between the the discharge rollers to overlap with respect to the discharge roller in the above paper guide member and the other portion, said sheet
The paper discharge auxiliary roller is provided so as to have a difference between the paper discharge force and the static friction force .

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. This embodiment is applied to a paper discharge mechanism of a device capable of printing 136 characters of alphabets. FIG. 1 is a front view of the paper discharge mechanism of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG. The paper discharge mechanism 1 is a paper discharge roller 1 having a jagged cross section.
0a, a discharge roller 10b having a round cross section, a discharge roller shaft 11, and a gear 14 serving as a power transmitting means, a discharge cover 5, a discharge plate 2, a discharge plate 2, and a discharge roller unit. 9, a fixing means for fixing the sheet discharge cover 5 and the sheet discharging plate 2, and a holding means for rotatably holding the sheet discharging roller unit 9. The discharge roller unit 9 includes three discharge rollers 10a each having a knurled cross section on the side of the small spar, and three discharge rollers 10b each having a round cross section on the side of the large spar. A paper discharge roller 10 made of rubber or a material having a high coefficient of friction similar to that provided for pulling the paper is provided on a paper discharge roller shaft 1.
1 is fixed by fixing means such as press-fitting so as not to idle. The gear 14 is also fixed to the discharge roller shaft 11.

In FIG. 2, the paper discharge cover 5 has a single plate portion 5a connected to the column direction, and a rib portion 5b for guiding the paper at its ridge line is formed in an integral structure. The plate portion 5a at this position of the digit extends to the lowest position, and the rib portion 5b also extends to the same position.
The pressurizing mechanism includes a paper discharge cover 5 and a paper discharge roller unit 9. When the leading edge of the sheet is sent into the sheet ejection mechanism 1, the sheet is guided along the rib 5b of the sheet ejection cover 5, and the sheet enters between the rib 5b and the sheet ejection plate 2. It enters between the paper rollers 10a.

As shown in FIGS. 1 and 2, the rib portion 5b and the paper discharge roller 10 are disposed on both sides of the paper discharge roller 10 with a gap of P and an overlap amount of N. The force that presses the sheet against the discharge roller 10 is determined by the gap P, the overlap amount N, and the spring property of the sheet. The paper discharge force due to the friction of the paper is determined by the dynamic friction coefficient when the paper discharge roller 10 is in contact with the paper and rotating, and the pressing force. When the paper discharge roller is stopped and printing is being performed, the paper tends to return to its original shape due to its spring property. The upstream side of the sheet is fixed by the tractor as in FIG. 9 and is fixed, and the sheet on the downstream side attempts to return to the upstream side. That is, the paper contained in the paper discharge mechanism 1 is pulled back to the platen side, and sags around the platen.
This force for returning the sheet is called a sheet return force. When the sheet is pulled back, the force for pressing the sheet against the sheet discharge roller (the same as the force for pressing the sheet to the rib portion 5b) and the sheet and the rib portion 5b
A first static friction force which is a product of a static friction coefficient between the sheet, a force for pressing the sheet against the sheet discharging roller 10, and a sheet and the sheet discharging roller 10.
A second static friction force, which is the product of the coefficient of static friction between the two, acts. The frictional force obtained by adding the first static frictional force and the second static frictional force is the static frictional force.

FIG. 3 is a sectional view of section BB in FIG. 1, and the contact length S between the rib 5b and the sheet 3 is AA shown in FIG.
It is shorter than the cross section. Discharge roller 1 with round cross section
0b is located at a position where the overlap amount N with the rib portion 5b becomes a predetermined value.

Here, the friction between the jagged discharge roller 10a, the round discharge roller 10b and the paper 3 will be described.
The coefficient of kinetic friction and the coefficient of static friction between the sheet 3 and the sheet discharging roller 10 are related to the contact area between the sheet 3 and the sheet discharging roller 10. As described with reference to FIG. 2, the contact area between the jagged paper ejection roller 10a and the sheet 3 is equal to the length R of the portion where the jagged paper ejection roller 10a and the rib portion 5b overlap. This is the area where the ridge 10c of the paper roller 10a is in contact with the paper 3, and the valley 10d is not in contact with the paper 3. On the other hand, the contact area between the round discharge roller 10b and the sheet 3 described with reference to FIG.
And the length R where the rib portion 5b overlaps
, And is larger than the contact area between the jagged paper discharge roller 10 a and the paper 3. Round discharge roller 1
Ob and the contact area of the sheet 3 are large, so that the kinetic friction coefficient and the static friction coefficient between the round ejection roller 10b and the sheet 3 are larger than the kinetic friction coefficient and the static friction coefficient between the jagged ejection roller 10a and the sheet 3. Become. Therefore, the paper discharging force due to the frictional force, which is the product of the dynamic friction coefficient when the paper 3 and the round paper discharging roller 10b rotate and the force pressing the paper 3, can be made larger than when the jagged paper discharging roller 10a is used. Similarly, the second static friction force, which is the product of the static friction coefficient between the round discharge roller 10b and the sheet 3 and the force pressing the sheet 3, can be made larger than when the jagged discharge roller 10a is used. As shown in FIG. 1, the plate portion 5a of the paper ejection cover 5 goes up as it goes to the side of the digit smaller than about the 40th digit, and the plate portion 5a goes up as it goes to the side of the larger digit. This is because the wide paper is the first 40th digit and the output cover 5
This is for guiding the paper gradually between the paper discharge cover 5 and the paper discharge plate 2 on the side smaller than 40 digits and on the larger digit side as the paper is fed downstream thereafter. The plate portion 5a and the rib portion 5b of the discharge cover 5 have four
The reason for extending to the bottom in the 0th digit is to guide the paper between the paper output cover 5 and the paper output plate 2 even when a narrow paper is used. The sheet discharging force of the sheet is affected by the contact length S between the rib portion 5b in the sheet running direction and the sheet 3 together with the gap P. When the contact length S is long, the constraint on the sheet is large, and the same effect is obtained as apparently the spring property of the sheet is increased. When the contact length S is short, the degree of freedom of the sheet is increased, and the same effect as when the spring property of the sheet is apparently reduced is obtained. Regarding the static friction force in the traveling direction of the sheet, the static friction force increases when the contact length S between the sheet, the rib portion 5b and the sheet 3 is long, and the static friction force decreases when the contact length S is short. Therefore, in the vicinity of the 40th digit, the spring property of the sheet increases, and the vertical reaction between the sheet and the discharge roller 10 increases, so that the sheet discharge force and the static friction force, which are the product of the vertical reaction and the dynamic friction coefficient, increase the rib portion 5b and the sheet 3. Is large because the contact length S is long. Although the contact length S is short on the large girder side, the friction coefficient between the sheet 3 and the paper discharge roller 10 is increased by using the round discharge roller 10b on the large girder side, and the paper discharge force and the static friction force are reduced on the large girder side. It can be balanced on the large girder side.

As described above, the structure using the paper discharge cover 5 in which the plate portion 5a and the rib portion 5b of about forty digits, which have the same track record as the conventional one, extend to the lowest position at a low cost without increasing the number of parts. Thus, the floating of the paper due to the imbalance between the paper discharging force and the static friction force can be reduced. By using the discharge roller 10 having the same outer diameter of the discharge roller and different roller cross-sectional shapes from the jagged shape and the round shape, it is possible to balance the discharge force and the static friction force without changing the peripheral speed of the discharge roller 10. In addition, the same stability of the discharge condition can be ensured as before. In this embodiment, the discharge roller unit 9 includes three discharge rollers 10a having a knurled cross section on the side of the smaller spar, and three discharge rollers 10b having a round cross section on the side of the larger spar. However, the purpose is to balance the paper discharge force and the static frictional force at each digit position, and the number of the jagged paper discharge rollers 10a and the number of the round paper discharge rollers 10b depend on the state of the paper discharge mechanism 1. Are not limited to this embodiment.

There are other methods for balancing the paper discharge force and the static friction force between the small and large girders.

One method is to make the overlap amount N on the large digit side larger than the overlap amount N on the small digit side. By increasing the overlap amount N, the paper discharge force and the static friction force can be increased. This can be realized by changing the cross-sectional shape in the direction perpendicular to the rotation axis of the discharge roller, specifically, by increasing the roller diameter of the discharge roller 10 disposed on the side of the large girder. The overlap amount N can also be increased by changing the protruding amount of the rib portion 5b without changing the roller diameter.

As another method, there is a method in which the gap P in the girder direction on the large girder side is made smaller than the gap P in the girder direction on the smaller girder side. By reducing the gap P on the large girder side, the paper discharging force and the static friction force can be increased. This can be realized by changing the cross-sectional shape of a plane parallel to the rotation axis of the paper discharge roller 10. The clearance P can be reduced by eliminating the chamfers at both ends of the discharge roller 10 in the axial direction. In addition, this can be realized even if the length of the discharge roller 10 in the axial direction is increased. Also, the rib 5b can be used without changing the paper discharge roller.
The gap P can also be reduced by bringing the position in the spar direction closer to the paper discharge roller. Even in such a method, the peripheral speed of the paper discharge roller can be made the same, and the paper discharge conditions can maintain the same stability as in the related art.

As described above, the plate portion 5a and the rib portion 5b of the sheet discharge cover 5 are provided so that the sheet can be guided between the sheet discharge cover 5 and the sheet discharge plate 2 even when a narrow sheet is used. Even in the structure extending to the lowest position at the 40th digit, the paper discharge force, the static frictional force, and the sheet return force at each digit position are balanced without using any additional component requiring a special cost, so that the paper floating is reduced. Even if it is hit with a wire of the head, the vibration of the paper is small and the noise can be reduced.

FIG. 4 is a front view of a main part of a paper discharging mechanism according to a second embodiment of the present invention. FIG. 5 is a sectional view of the section EE of FIG. Here, a paper discharge auxiliary roller 32 is used as a component of the pressure mechanism instead of the paper discharge cover. The discharge assist roller unit 30 includes the discharge assist roller shaft 3.
1, a paper discharge auxiliary roller 32 is rotatably inserted.
The second rib portion 22b is used. The paper discharge roller 24 and the paper discharge auxiliary roller 32 are arranged with a center distance at which the overlap amount T becomes a predetermined value. The paper discharge roller 24 and the paper discharge auxiliary roller 32 have a gap W between each other in the beam direction. Since the sheet 27 comes into contact with the rib portion 22b and is guided and enters between the rollers, the shape of the rib portion 22b also affects the sheet discharging force and the static friction force. Clearance W and overlap amount T
The paper discharge force and the static friction force of the paper are determined by the spring property of the paper and the contact state between the rib portion 22b and the paper 27. 6 and 7 are sectional views of a third embodiment of the present invention, and only the differences from FIG. 5 will be described. Plate part 3 of paper output cover 33
A paper discharge spring 35 made of a polyester sheet, which is a kind of plastic sheet, is fixed to the back surface of 3a by a double-sided tape 36 which is a fixing means. The paper discharge spring 35 has spring portions 34 at both ends, and the spring portions 34 hold the paper 38 at both ends of the paper discharge roller 37. Spring part 34
Is supported by an auxiliary roller shaft 39 in the middle of the spring to stabilize the spring property and stabilize the spring. The paper discharge spring 35 can increase the winding angle of the paper around the paper discharge roller 37, and can stably increase the paper discharge force and the static friction force.

[0017]

As described above, the paper discharge mechanism of the present invention covers the paper discharge roller on the lower side of the platen in the paper conveyance direction, and the portion for guiding the paper is long in the paper discharge direction. In other parts, in a paper ejection mechanism of a printer provided with a short paper ejection cover, a paper ejection force is applied between a paper ejection roller and an overlap member provided on the paper ejection cover in a paper guiding portion. Means for reducing the static frictional force and increasing the other parts, and in the paper guiding part, a paper discharge roller having a knurled peripheral surface,
Other integrally provided discharge rollers round the respective common axis in a portion, further, in the above paper-inducing moiety, widely <br/> the axial distance between the discharge roller and the overlapping member, The other portions are made narrower, and furthermore , while forming each of the overlap members at a fixed interval, the discharge rollers disposed between the overlap members are shortened in the axial direction in the paper guiding portion, It formed long in other parts, in addition, as the overlap member, between the the discharge rollers to overlap with respect to the discharge roller in the above paper guide member and the other portion, the upper
By arranging the paper ejection auxiliary roller so that there is a difference between the paper ejection force and the static friction force of the recording paper, the paper ejection force and the static friction force at each position in the paper width direction can be increased and balanced. As a result, the floating of the paper can be reduced, and as a result, the generation of noise during printing can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a paper discharge mechanism of the present invention.

FIG. 2 is a sectional view of section AA in FIG. 1;

FIG. 3 is a cross-sectional view of a cross section BB of FIG. 1;

FIG. 4 is a front view showing a second embodiment of the paper ejection mechanism of the present invention.

FIG. 5 is a sectional view of a section EE of FIG. 4;

FIG. 6 is a sectional view of a third embodiment of the paper ejection mechanism of the present invention.

FIG. 7 is a perspective view of main parts of FIG. 6;

FIG. 8 is a front view of a conventional paper discharge mechanism.

FIG. 9 is a cross-sectional view of a cross section CC of FIG. 8;

FIG. 10 is a sectional view taken along section DD of FIG. 8;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 paper discharge mechanism 2 paper discharge plate 5 paper discharge cover 5b rib 5a plate 9 paper discharge roller unit 10 paper discharge roller 10a paper discharge roller 10b with cross section 10b discharge roller with round cross section 11 paper discharge roller shaft P gap N overlap amount

Claims (5)

(57) [Scope of request for utility model registration] 1. A paper discharge device for a printer, which is provided with a paper discharge cover on a lower side of a platen in a paper conveyance direction so as to cover a paper discharge roller, and has a paper discharge cover that is long in a paper discharge direction at a portion for guiding paper and is short at other portions. In the mechanism, between the discharge roller and the overlap member provided on the discharge cover, means for reducing the paper discharge force and static friction force of the paper in a portion for guiding the paper and increasing it in other portions. A paper discharge mechanism for a printer, comprising: 2. A paper discharge roller having a knurled peripheral surface in the paper guiding portion and a circular discharge roller in other portions integrally provided on a common shaft. Item 2. A paper discharging mechanism of the printer according to Item 1. 3. The paper ejection mechanism according to claim 1, wherein an axial space between the paper ejection roller and the overlap member is widened in the paper guiding portion and narrowed in other portions. 4. The method according to claim 1, wherein each of the overlap members is formed at a predetermined interval, and the discharge rollers disposed between the overlap members are short in the axial direction at the sheet guiding portion.
4. A paper discharge mechanism for a printer according to claim 1, wherein other portions are formed long . 5. The paper guide member and other portions between the paper discharge rollers so as to overlap the paper discharge rollers as the overlap member ,
2. The paper ejection mechanism according to claim 1, wherein a paper ejection auxiliary roller is provided so as to have a difference between the paper ejection force and the static friction force of the paper.