JPH10310279A - Recording paper delivery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently reduce a change of carrying quantity of recording paper by furnishing a pinch roller having conical shaft parts on both ends and supporting head ends of the conical shaft parts of the pinch roller by a holder free to rotate. SOLUTION: A pinch roller 32 having shaft parts 321 on both ends is supported on a holder 33 having a bearing part free to rotate, and a plural number of these pinch rollers 32 are arranged. The pinch rollers 32 are respectively and independently pressurized on a paper delivery roller 31 by a spring 34 working on the holder 33. Simultaneously, recording paper 8 clamped between the paper delivery roller 31 and the pinch rollers 32 is carried in the auxiliary scanning direction by rotationally driving the paper delivery roller 31. It is desirable to make a tangential part of the pinch rollers 32 and the paper delivery roller 31 approach a recording head 11 to the utmost so as to take a recording area in the auxiliary scanning direction on the recording paper 8 wide, and it is desirable to reduce an outside diameter of the pinch rollers 32 as small as possible for it. The shaft part 321 of the pinch roller 32 is shaped conical, and a head end of the shaft part 321 is shaped materially pointed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper feeder for a printer or the like, and more particularly to a recording paper feeder for an ink jet printer which records a color image or the like with high definition.

[0002]

2. Description of the Related Art A recording paper feeder of an ink jet printer conventionally used has a structure as shown in FIG.

[0003] The pinch roller 32 has a shaft portion 321.
It is supported by a bearing part 331 of the holder 33 and is pressed against the paper feed roller 31 by a spring 34 with a predetermined force.

[0004] The pinch roller 32 and the paper feed roller 31
It is located upstream with respect to the recording head 11.

The driving mechanism of the paper feed roller 31 uses a pulse motor 51 as a drive source and gears 35, 5 as transmission means.
5 and the like are used.

Further, on the upstream side, there is a paper feed mechanism (not shown).

The operation of the recording paper feeder having such a configuration is as follows. That is, the recording paper 8 pressed by the paper feed mechanism 6 against the joint between the paper feed roller 31 and the pinch roller 32 enters the space between the paper feed roller 31 and the pinch roller 32 by the rotation of the pulse motor 51, and the recording head It is sent to a position facing 11. The recording head 11 is scanned in a direction orthogonal to the recording paper transport direction to record data for one scan, and then the pulse motor 51 is rotated by a predetermined amount, whereby the paper feed roller 31 is rotated by a predetermined amount via a transmission unit. The recording paper 8 sandwiched between the paper feed roller 31 and the pinch roller 32 is transported by a predetermined amount.

[0008]

In recent years, there has been an increasing demand for outputting a high-definition color image by a printer. In order to realize this, it is necessary to arrange dots at a predetermined correct position at a fine pitch, that is, higher recording accuracy is required. For this reason, it has become increasingly important to convey recording paper with higher accuracy even in a recording paper feeder of a printer.

[0009] However, it is difficult to further improve the recording paper conveyance accuracy because of the structure of the conventional example as it is.

More specifically, when the recording paper 8 is fed while being sandwiched between the paper feed roller 31 and the pinch roller 32, the recording paper 8 is supplied with a conveying force from the paper feed roller 31, and starts to move, thereby causing the pinch roller 32 to rotate. give. The transport force of the paper feed roller 31 is generated by the frictional force between the recording paper 8 and the paper feed roller 31 due to the pressing force of the spring 34. At the same time, the pressing force of the spring 34 causes the pinch roller 32
A frictional force is also generated between the shaft portion 321 and the bearing portion 331 of the holder 33. This force acts in a direction that hinders the rotation of the pinch roller 32 (hereinafter, referred to as an axial loss), and acts in a direction that hinders the travel of the recording paper. The running disturbance due to the shaft loss is caused by the recording paper 8
Along with the rear load (back tension) at the time of conveyance, the travel of the recording paper 8 causes a slip, and the conveyance amount of the recording paper 8 becomes smaller than a predetermined value. The amount of the slip varies depending on the type of the recording paper 8 and the magnitude of the back tension. Therefore, it is very difficult to keep the transport amount of the recording paper 8 constant in the recording paper feeder of the printer, in which the back tension is inevitable depending on the position of the recording paper 8 in the path using various recording papers 8. Met.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a recording apparatus which is capable of recording even if the type of recording paper or the magnitude of the back tension in the recording paper transport path changes. An object of the present invention is to provide a recording paper feed device in which a change in the paper transport amount is small.

[0012]

SUMMARY OF THE INVENTION A recording paper feeder according to the present invention comprises a paper feed roller which rotates to convey a recording paper, and a recording paper which is held between the paper feed roller and the paper feed roller. In a recording paper feeder comprising pinch roller means pressed by feed roller means, and holder means rotatably supporting a shaft part of the pinch roller means, a pinch roller means having conical shaft parts at both ends; And holder means for rotatably supporting the tip of the conical shaft portion of the pinch roller means.

[0013]

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

FIG. 1 is a perspective view showing an embodiment of a recording paper feeder according to the present invention, FIG. 2 is a cross-sectional view of FIG. 1 along a recording paper conveyance direction, and FIG. 3 is a partially enlarged view of FIG.

In these figures, reference numeral 11 denotes a recording head, in which a plurality of recording elements are arranged at a constant element pitch in the sub-scanning direction (recording paper transport direction), and are arranged to face the recording paper.

Reference numeral 21 denotes a carriage, and the recording head 11
Is driven by a carriage motor 22 via, for example, a timing belt 24, and reciprocates along a guide shaft 23 in a main scanning direction (a direction orthogonal to a recording paper conveyance direction).

The main components of the recording paper feeder of the present invention include a paper feed roller 31 that conveys the recording paper 8 by rotating, a pulse motor 51 that is a driving source of the paper feed roller 31, and a pulse motor 51. The gears 55 and 35, which are means for transmitting the generated driving force, the pinch roller 32 pressed by the paper feed roller 31 with the recording paper 8 interposed between the paper feed roller 31, and the shaft 321 of the pinch roller 32 (With a bearing portion 331).

The paper feed roller 31 has a surface in contact with the recording paper 8 made of a material having a high coefficient of friction with respect to the recording paper 8, and is disposed upstream of the path of the recording paper 8 with respect to the recording head 11. I have. The paper feed roller 31 is rotatably supported by a bearing 311 provided on a support plate 43, and a gear 35 is fixedly connected to one end of the paper feed roller 31 by means such as press fitting.

Pinch roller 3 having shaft portions 321 at both ends
A plurality 2 are rotatably supported by a holder 33 having a bearing portion 331 and are provided in plurality. Pinch roller 32
Are pressed independently by the paper feed rollers 31 by springs 34 acting on the holders 33, and by rotating the paper feed rollers 31, the recording paper
Is transported in the sub-scanning direction. In order to widen the recording range in the sub-scanning direction on the recording paper 8, it is desirable that the tangent between the pinch roller 32 and the paper feed roller 31 be as close as possible to the recording head 11.
It is desirable that the outer diameter of No. 2 be as small as possible.

The engagement between the shaft 321 of the pinch roller 32 and the bearing 331 of the holder 33 will be described in more detail with reference to FIG.
Has a conical shape, and the tip 322 of the shaft portion 321 has a substantially pointed shape.

The bearing 331 of the holder 33 is formed in a V-shaped valley shape, and narrows toward the spring 34 side.

The shaft portion 321 of the pinch roller 32 and the bearing portion 331 of the holder 33 are engaged in such a manner that the ends of the shaft portions 321 at both ends of the pinch roller 32 enter along the bottom line of the valley of the bearing portion 331 of the holder 33. And the holder 3 with the spring 34
3 is urged toward the paper feed roller 31 so that the shaft 3
21 is held at a position where the distance between the two front ends and the distance between the two valleys of the bearing portion 331 match. At this time, the engagement state between the shaft portion 321 of the pinch roller 32 and the bearing portion 331 of the holder 33 is almost point contact, and there is no degree of freedom in the sub-scanning direction and the direction perpendicular to the plane of the recording paper 8. ,
Only rotation is held in a free form.

Reference numeral 51 denotes a pulse motor, and a gear 55 is fixedly connected to the rotary shaft by means such as press fitting.

The gear 35 connected to the pinch roller 31 and the gear 55 connected to the pulse motor 51 are engaged to constitute driving force transmitting means, and the paper feed is performed by rotating the pulse motor 51 by a predetermined amount. The roller 31 rotates a predetermined amount according to the speed reduction ratio.

Reference numeral 6 denotes a paper feed mechanism, which is driven by a paper feed roller 61 rotated by a pulse motor 51.
The recording paper 8 stored in the printer 5 is fed into a recording paper feeder of the printer. A one-way clutch mechanism is provided in the power transmission system of the paper feeding mechanism, and the recording paper 8 is fed to a recording paper feeding device, and after the recording paper 8 is sandwiched between the paper feeding roller 31 and the pinch roller 32, the recording paper 8 The movement of the feed roller 6
1 is idle.

A recording paper end sensor 81 is provided between the paper feed roller 61 and the paper feed roller 31 along the path of the recording paper 8 to detect the end face position of the recording paper 8 in the transport direction. I do.

Reference numerals 71 and 72 denote recording paper 8 after recording, respectively.
And a paper discharge roller and a paper discharge driven roller provided downstream of the path of the recording paper 8 with respect to the recording head 11 for paper discharge. The paper discharge roller 71 is driven by the pulse motor 51 similarly to the paper feed roller 31. The driving amount of the outer periphery of the paper discharge roller 71 is controlled by the pulse motor 51 so that the recording paper 8 does not slack on the front surface of the recording head 11.
Is set to be several percent larger than the driving amount of the outer periphery of the paper feed roller 31 with respect to the same rotation amount.

Reference numeral 9 denotes a protection device that protects the ink ejection surface of the recording head 11 and suctions ink when the inkjet head is used as the recording head 11.

Next, the operation of the printer having the above configuration and the recording paper feeder thereof will be described.

When the data to be recorded is received, the pulse motor 51 starts rotation (reverse rotation) for paper feeding. The feed roller 61 is driven by the rotation of the pulse motor 51,
One sheet of recording paper 8 stored in the paper feed tray 65 is selected and fed toward the narrow pressure portion between the paper feed roller 31 and the pinch roller 32. The selected recording paper 8 is fed to the paper feed roller 6
When the leading end of the recording paper 8 is detected by the paper end sensor 81 in the path between the paper feed roller 31 and the paper feed roller 31, it is determined in advance that the leading end of the recording paper 8 reaches the paper feed roller 31 from that position. Sent by the amount given. The leading edge of the recording paper 8
The pulse motor 51 stops rotating when the paper feed roller 31 and the pinch roller 32 are sufficiently pressed against the narrow pressure part where the paper feed roller 31 and the pinch roller 32 are pressed and the skew is corrected, and the paper feeding operation ends.

Next, the pulse motor 51 starts normal rotation for cueing the recording paper 8. The paper feed roller 31 is driven by the rotation of the pulse motor 51. The recording paper 8 is sandwiched and sent between the paper feed roller 31 and the pinch roller 32, and is sent out by a predetermined amount to face the recording head 11 and the cueing operation ends. At this time, the paper feed roller 61 idles in the drawing direction of the recording paper 8 as described above, and the recording paper 8 is pulled out from the paper feeding tray 65 with a relatively small load.

After the feeding and cueing of the recording paper 8 are completed as described above, the carriage motor 22 starts rotating. After the carriage 21 moves in the main scanning direction and the recording element of the recording head 11 mounted on the carriage 21 reaches a recording area in the main scanning direction, the recording element is selectively energized according to the recording data, and 8, an image for one scan is recorded in the main scanning direction recording area.

After the recording of the first scanning is completed, the driving of the carriage motor 21 is stopped, the pulse motor 51 is driven, and the recording paper 8 is rotated by a predetermined amount in the sub-scanning direction by the rotation of the paper feed roller 31. Transport.

Thereafter, the carriage motor 21 is driven to move the recording head 11, and an image is recorded by the second scanning.

Hereinafter, the operation of moving the carriage 21 and the operation of transporting the recording paper 8 are repeated.

When the recording approaches the end of the recording paper 8, the end of the recording paper 8 passes through the paper end sensor 81, and the end of the recording paper 8 is detected by the paper end sensor 81. Thereafter, the moving operation of the carriage 21 and the conveying operation of the recording paper 8 are repeated until an image by the final scan allocated to the end of the recording paper 8 is recorded, and the recording of one page is completed.

In this transport operation, when the recording paper 8 is transported while being sandwiched between the paper transport roller 31 and the pinch roller 32, the transport force is given from the paper transport roller 31 and
By starting to move, the pinch roller 32 is given a rotational force. The transport force of the paper feed roller 31 is generated by the frictional force between the recording paper 8 and the paper feed roller 31 due to the pressing force of the spring 34. At the same time, a frictional force is generated between the shaft portion 321 of the pinch roller 32 and the bearing portion 331 of the holder 33 by the pressing force of the spring 34. This force acts in a direction that hinders the rotation of the pinch roller 32 (axial loss) and acts in a direction that hinders the running of the recording paper. The running obstruction due to the axial loss causes the running of the recording paper 8 to slip along with the rear load (back tension) during the conveyance of the recording paper 8, and the conveyance amount of the recording paper 8 is deviated from a predetermined value and varies. Let it.

This relationship will be described in more detail with reference to FIG.

As shown in FIG. 5, the pressing force of the spring 34 (to the paper feed roller 31 of the pinch roller 32) is N, the friction coefficient between the recording paper 8 and the paper feed roller 31 is μ, and the pinch roller 32 The friction coefficient between the shaft portion 321 and the bearing portion 331 of the holder 33 is μ ′, and the pinch roller 32
Is the outer diameter of D, and the diameter of the shaft 321 is d, the force f that hinders the conveyance of the recording paper 8 due to the shaft loss is the balance formula of the rotational moment acting on the shaft 321: f × (D / 2) = μ '× N
From x (d / 2), f = μ ′ × N × (d / D) (1)

The total force P that inhibits the conveyance by adding the back tension B is P = f + B = μ ′ × N × (d / D) + B (2)

On the other hand, the transport force F that the paper feed roller 31 can apply to the recording paper 8 is as follows: F = μ × N (3)

Therefore, as the ratio of P to F increases, the slip of the recording paper 8 during running increases.

According to the configuration of the present embodiment, the shaft portion 321 of the pinch roller 32 is formed in a conical shape and is engaged with the bearing portion 331 of the holder 33 in a substantially point-contact state. The value of the shaft diameter d of the pinch roller 32 in the expression (1) or (2) becomes very small. That is, the force f that hinders the conveyance of the recording paper 8 due to the axial loss of the pinch roller 32 is extremely small. Further, in order to obtain a wider recording range, the pinch roller 32 is used.
F can be made sufficiently small even if the outer diameter D of the is made small.

Therefore, the paper feed roller 31 moves the recording paper 8
Thus, the ratio of the total force P that hinders the conveyance to the conveyance force F that can be applied to the recording paper 8 is reduced, and the stable conveyance of the recording paper 8 without slippage when the recording paper 8 travels can be realized.

When the pressing force N by the spring 34 is increased, the value of F in equation (3) increases in proportion to N, whereas the value of P in equation (2) increases only slightly ( This is because the value of B is dominant), and the ratio of P to F is further reduced, so that more stable conveyance of the recording paper 8 can be expected.

Next, a specific example using a prototype recording paper feeder will be described.

FIG. 6 is a graph in which the abscissa represents the amount of back load (back tension) applied to the recording paper 8 during conveyance, and the ordinate represents the single conveyance amount of the recording paper 8 at that time.

The curves (a) and (a) shown in the graph of FIG. 6 show the results of a conveyance test by a recording paper feeder using the pinch roller 32 of the present invention. The pinch roller 32 used in the test had an outer diameter D = φ4 mm. The shaft portion 321 was formed into a right circular cone shape using a steel material, and the tip was machined to have a spherical radius of 0.1 mm or less. The two curves are respectively
(A) shows a case where the paper-based recording paper 8 is conveyed, and (A) shows a case where the film-based recording paper 8 which is more likely to slip is conveyed.

The curves (a) and (i) shown in the graph show the results of a transport test using a conventional recording paper feeder as a comparative example. The outer diameter D of the pinch roller is the same as the above example, D = φ4
mm, the shaft portion was also made of steel, the shape was cylindrical, and the outer diameter d was d = φ2 mm. Similarly to the above, each of the two curves (a) represents the result of transporting the paper-based recording paper 8, and (ii) represents the result of transporting the film-based recording paper 8.

The test is performed with the back tension applied.
In the state where all the recording paper paths on the upstream side are removed and no back tension is applied, when the same amount of back tension as the assumed load is applied, and when the back tension of twice the assumed load is applied, Each transport amount was measured.

As a result, as shown in the graph of FIG. 6, over the entire range c of the assumed variation in back tension, the conveyance by the recording paper feeding device of the present invention is as follows. 1. The variation range of the carry amount is small (comparison of the sizes of a and b in the figure); It was confirmed that the absolute value of the carry amount was large (comparison of the positions a and b in the figure).

A dotted line (A ′) is shown in the graph of FIG.
(A ') (I') (I '), the curve (A) (A)
(A) The extension lines of (i) intersect approximately at points J and K.

The values in the vertical axis direction at points J and K represent the transport amount (without slippage) when there is no back tension or axial loss of the pinch roller 32, and the values in the horizontal axis direction are from the origin. Represents the magnitude of the force that hinders the conveyance due to the respective axis loss.

That is, the conveyance by the recording paper feeding device of the present invention is: It was confirmed that the force that hinders the conveyance due to the axial loss caused by the rotation of the pinch roller 32 was small.

When the same test was performed by increasing the pressing force N by the spring 34, the curves (A), (A) and (A) were obtained.
(I) In both cases, the slope became gentle. However, in the comparative example, since the value of f becomes larger in proportion to the increase of N, even if the slopes of the curves (a) and (i) become gentle, a decrease in the amount of slip cannot be expected so much, and the transfer accuracy cannot be improved. No improvement can be expected.

On the other hand, in the present example, the value of f which increases in proportion to the increase of N is small because the value of d in the equation (2) is small, as described above, so that the absolute value is still very small. A) The variation range of the transport amount becomes smaller due to the gentle inclination of (a). That is, in the present embodiment, it is possible to use a greater pressing force than in the past in order to obtain higher conveyance accuracy of the recording paper 8.

FIG. 7 shows another embodiment of the present invention.

FIG. 7A shows the shaft portion 3 of the pinch roller 32.
The conical shape of No. 21 is a thread-wound conical shape having a dent in the middle. In this case, since the angle θ at which the bearing portion 331 of the holder 33 engages with the shaft portion 321 can be made large, it is suitable when the bearing portion 331 of the holder 33 is formed of a relatively soft material.

FIG. 7B shows the shaft 3 of the pinch roller 32.
21 is a barrel-shaped cone having a bulge in the middle. Since the strength of the conical portion is higher, the diameter of the pinch roller 32 can be further reduced.

As shown in FIG. 7B, it is also preferable that the bearing 331 of the holder 33 is formed in a funnel shape.

[0061]

As is apparent from the above description, according to the present invention, the shaft of the pinch roller is formed in a conical shape, and the tip is rotatably supported by the holder. Since the force that hinders the conveyance of the recording paper due to the loss can be made extremely small, even if the type of the recording paper or the magnitude of the back tension in the conveyance path of the recording paper changes, the conveyance amount of the recording paper can be reduced. This has the effect that a recording paper feeder with a sufficiently small change can be obtained.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing a configuration of a recording paper feeder according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the recording paper feeding device shown in FIG. 1 along a recording paper conveyance direction.

FIG. 3 is a partially enlarged view of the recording paper feeding device shown in FIG. 2;

FIG. 4 is a diagram showing an engagement state between a pinch roller shaft and a bearing of a holder in the recording paper feeder according to one embodiment of the present invention;

FIG. 5 is a diagram illustrating the operation of the recording paper feeder according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating the operation of the recording paper feeder according to the embodiment of the present invention.

FIG. 7 is a diagram showing a recording paper feeding device according to another embodiment of the present invention.

FIG. 8 is a diagram showing a conventional technique.

[Explanation of symbols]

 Reference Signs List 11 recording head 21 carriage 22 carriage motor 23 guide shaft 31 paper feed roller 32 pinch roller 321 pinch roller shaft 332 tip of pinch roller shaft 33 holder 331 holder bearing 34 spring 35 gear 43 support plate 51 pulse motor 55 Gear 61 Paper feed roller 65 Paper feed tray 71 Paper discharge roller 72 Paper discharge driven roller 8 Recording paper

Claims (4)

[Claims] 1. A paper feed roller means for conveying a recording paper by rotating, and a pinch roller means for nipping the recording paper between the paper feed roller means and being pressed by the paper feed roller means. And a holder means for rotatably supporting a shaft part of the pinch roller means, wherein the pinch roller means having conical shaft parts at both ends;
The holder means for rotatably supporting the tip of the conical shaft of the pinch roller means. 2. The recording paper feeding device according to claim 1, wherein the conical shape of the shaft portion of the pinch roller means is a thread-wound conical shape having a dent in the middle. 3. The recording paper feeding device according to claim 1, wherein the conical shape of the shaft portion of the pinch roller means is a barrel-shaped cone having a bulge in the middle. 4. The recording paper feeder according to claim 1, wherein the conical shape of the shaft of said pinch roller means is a straight cone.