JP2002137472A - Sheet carrying roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high accuracy sheet carrying roller in which carrying accuracy of a print sheet is enhanced by suppressing variation in the diameter, and thereby the outer circumferential length, of a roller piece due to temperature variation. SOLUTION: A roller piece 8 comprises a core 9 of polyphenylene resin press fitted with an ethylene propylene rubber 10 of 1 mm thick exhibiting excellent wear resistance. When a roller shaft 7 is applied with the resin core 9, as a base, and press fitted with the rubber 10, thermal conduction from the metallic roller shaft 7 is suppressed while reducing the volume of the rubber 10 and variation in the diameter of the roller piece 8 due to thermal expansion can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-precision paper transport roller and a printer equipped with the roller.

[0002]

2. Description of the Related Art A conventional impact printer has a feature that it can print from a single print sheet to a copy sheet in which a plurality of print sheets are stacked, and is used for printing various slips. The predominant form is preprinted paper in which a frame for designating the printing position is printed in advance, but if the transport amount of the printing paper is inappropriate, characters are printed outside this frame. Problems arise.

[0005] Causes of an inappropriate conveyance amount of the printing paper include errors in the suction amount of the printing paper, skew, slip, and a change in diameter due to thermal expansion of the roller piece due to a change in outside air temperature and a temperature inside the apparatus.

FIG. 5 is a sectional view of a roller piece of a conventional paper transport roller.

Referring to FIG. 5, the roller piece 8 'is made of a rubber 10 having a large coefficient of friction in order to prevent slippage of the printing paper. There is a problem that the diameter of the roller piece 8 'changes.

The diameter of the roller piece 8 'is 16.17 m.
m is mainly used, but the diameter of the roller shaft 7 is φ6 mm.
Φ10 mm, and the thickness of the rubber portion 10 ′ is 5.1 mm
Or it is 3.1 mm. Taking a roller piece having a rubber thickness of 5.1 mm as an example, when the outside air temperature is between 5 ° C. and 38 ° C., the amount of change in the diameter of the roller piece becomes 0.07 mm as a measured value.

When the diameter of the roller piece changes, the rotation angle of the roller does not change, but the outer peripheral length changes, which changes the transport amount of the printing paper to be sent. When the diameter of the roller piece changes by 0.07 mm,
When printing A2 size paper vertically, which extends to 0.22 mm, the rollers rotate about 7 times, so that the printing position is shifted by 1.5 mm due to a temperature change.

In order to solve this problem, in the past, there has been known a paper transport roller or the like in which a metal roller having a low linear expansion coefficient is subjected to knurling or the like. Practicality was low due to problems such as the formation of roller marks on the printing paper and the occurrence of slip due to a low friction coefficient.

There is also a method of reducing the volume of rubber by increasing the diameter of the roller shaft. However, in the case of a metal roller shaft, when the roller shaft becomes hot, the heat is transmitted to the rubber on the surface and the rubber is heated. This causes the problem of expansion.

The roller disclosed in Japanese Unexamined Utility Model Publication No. Hei 2-111546 has a structure in which knurl-like irregularities are provided on the surface of a rigid body having small thermal expansion, and a substance having a large coefficient of friction is embedded in the concave surface. There is a problem that the cost of parts becomes high.

The rollers disclosed in JP-A-6-135072 and JP-A-9-152803 have the purpose of reducing the variation in the diameter of the roller when thermally expanded in the axial direction. The material of the rollers is a combination of silicon rubber and CR rubber and a combination of silicon rubber and fluorine rubber, and both have a problem that the change in diameter due to thermal expansion is large.

In Japanese Patent Application Laid-Open No. Hei 7-186484, a mechanism for detecting the transport amount of the printing paper is provided separately from the paper transport roller, so that the number of parts increases and the structure becomes complicated. There is a problem that costs increase.

[0013]

A first problem with this conventional paper transport roller is that the paper transport amount becomes inappropriate. The reasons for this include errors in the suction amount of the printing paper, skew, slip, and changes in the diameter due to the thermal expansion of the roller pieces due to changes in the outside air temperature and the internal temperature of the apparatus.

[0014] The second problem is that the diameter of the roller piece changes due to a change in temperature. The reason is,
This is because rubber having a large coefficient of friction is used as the material of the roller piece in order to prevent slippage of the printing paper, and this rubber has a high linear expansion coefficient.

A third problem is that, in order to solve the above problem, a metal roller having a low linear expansion coefficient is used such as a knurled sheet conveying roller or the like. However, metal has a problem that the surface is too hard to form a roller mark on the printing paper and that the friction coefficient is low and slippage occurs.

An object of the present invention is to provide a roller piece disposed on a roller shaft of a paper transport roller for transporting printing paper, using a resin having a small thermal expansion and a small thermal conductivity as a core, and forming a resin on an outer peripheral portion thereof. By providing a double structure in which rubber with a large coefficient of friction is press-fitted, a change in the diameter of the roller piece, that is, a change in the outer peripheral length of the roller piece with respect to a temperature change is reduced, and a high-precision paper transport roller with improved print paper transport accuracy is provided. Is to do.

[0017]

The paper transporting roller of the present invention has a resin core as a base, and a roller piece having rubber having excellent abrasion resistance press-fitted around its outer periphery. It is characterized by being installed at intervals.

Further, the paper transport roller of the present invention is based on a core made of polyphenylene ether resin, and has a metal roller shaft having an outer peripheral portion press-fitted with ethylene propylene rubber having excellent wear resistance. It is characterized by being installed at intervals.

Further, the paper transport roller of the present invention is characterized in that the rubber thickness is 0.8 to 1.2 mm.

Further, the paper transport roller of the present invention is used for transporting paper of a dot impact printer.

Further, the paper transport roller of the present invention is characterized in that it is used for transporting paper in a type impact printer.

Further, the paper transport roller of the present invention is characterized in that it is used for paper transport of an ink jet printer.

Further, the paper transport roller of the present invention is characterized in that it is used for transporting paper in a thermal printer.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a schematic configuration of a printer according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a sheet conveying roller used in this embodiment. FIG.
FIG. 3 is a sectional view taken along the line AA of the sheet transport roller of FIG. 2. Figures 1 and 2
With reference to FIG. 3 and FIG. 3, the configuration of the printer and the paper transport roller of this embodiment will be described.

In FIG. 1, the printing paper 4 is transported by the frictional force of the paper transport roller 5 as the paper transport roller 5 for transporting the printing paper 4 rotates. As shown in FIG. 2, a plurality of roller pieces 8 are arranged on a roller shaft 7 of the sheet conveying roller 5. The roller shaft 7 is made of metal and has a diameter of 6 mm to 10 mm, and the diameter of the roller piece 8 is 16.17 mm.

As shown in FIG. 3, the roller piece 8 is based on a resin core 9 made of polyphenylene ether (hereinafter, referred to as PPE) and has a 1 m thick outer peripheral portion having excellent wear resistance.
m of ethylene propylene rubber (hereinafter referred to as EPDM) 10. The roller shaft 7 is made of a resin core 9 as a base, and rubber 10 is pressed into the outer periphery thereof to suppress heat conduction from the metal roller shaft 7 and reduce the volume of the rubber 10. The structure is such that the amount of change in the diameter of the piece 8 is reduced.

Although the paper transport roller 5 in this embodiment is mainly used for a dot impact printer, it is also used for a type impact printer, an ink jet printer, a thermal printer and the like.

The operation of this embodiment will be described with reference to FIGS. 1, 2 and 3. Here, a case of a dot impact printer will be described.

The ink ribbon 3 and the printing paper 4 are sandwiched between the print head 1 and the platen 2. When a plurality of printing wires (not shown) of the print head 1 perform a striking operation toward the platen 2, the ink of the ink ribbon 3 adheres to the printing paper 4 and performs predetermined printing.

The printing paper 4 is sandwiched between a paper transporting roller 5 and a pinch roller 6, and is rotated by a paper transporting roller 5 (not shown) by a predetermined number of rotation steps of the stepping motor. Transported to

The number of rotation steps of the stepping motor is
This is a predetermined value, and the transport amount of the printing paper 4 is fed by the outer peripheral length of the roller piece 8 disposed on the paper transport roller 5. At this time, by using the roller piece 8 having a small thermal expansion with respect to a temperature change, a change in the outer peripheral length of the roller piece 8 is reduced, and stable paper conveyance accuracy is obtained.

In the core 9 of the roller piece 8, PP
Even if a resin other than E is used as a material, thermal expansion can be suppressed as in the above-described embodiment.

The rubber 10 may be a rubber other than EPDM, but it is necessary that the rubber 10 be made of a material which has excellent wear resistance and does not change its diameter due to aging.

Further, the thickness of the rubber 10 may be 1 mm or less in order to further reduce the thermal expansion. However, if it is too thin, the hardness of the roller piece becomes high, and there is a problem that a roller mark is left on the printing paper 4. Therefore, the thickness of the rubber 10 is 0.8
mm to 1.2 mm is appropriate.

[0036]

As described above, the first effect of the present invention is that the core of the roller piece is made of PPE having a small linear expansion coefficient.
Using resin, a 1mm thick EP
By press-fitting the DM rubber, the use of rubber having a large linear expansion coefficient is reduced, and the change in the diameter of the roller piece with respect to the change in the outside air temperature and the temperature inside the apparatus is reduced.

The coefficient of linear expansion of the PPE resin is 28 × 10 −6 / ° C. in a small one, and the coefficient of linear expansion of the rubber is 230 × 10 −6 / ° C.
２４０240 × 10 −6 / ° C. In the present invention, the amount of change in the diameter of the roller piece with respect to the temperature change,
What was conventionally 0.07 mm was reduced to 0.03 mm. FIG. 4 shows the amount of change in the diameter of the roller piece according to the prior art and the present invention due to the temperature change. As the test method, the diameter of the roller piece was measured by a non-contact laser measuring device after leaving the paper transport roller for 2 hours from the time when a predetermined environmental temperature was reached in the constant temperature and humidity chamber. .

The second effect is that the heat from the metal roller shaft is transferred to the EPDM on the roller piece surface by making the core of the roller piece a PPE resin having a low thermal conductivity.
This is what makes it hard to tell the rubber.

The third effect is that the change in the outer diameter of the roller piece, that is, the change in the rotation distance of the paper conveyance roller, is reduced due to the reduced change in the diameter of the roller piece, and the accuracy of the transfer position of the printing paper is reduced. Is to reduce the change. In the present invention, the printing position shift amount in the A3 vertical printing is suppressed from the conventional 1.5 mm to 0.6 mm.

A fourth effect is to obtain a high-precision sheet conveyance by a simple and inexpensive method.

The fifth effect is that high-quality printing can be provided by performing highly accurate paper transport.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of a printer according to an embodiment of the present invention.

FIG. 2 is a schematic view of a sheet conveying roller used in the embodiment.

FIG. 3 is a cross-sectional view of the paper transport roller of FIG. 2 taken along the line AA.

FIG. 4 is a diagram illustrating a change in a roller piece diameter due to a temperature change.

FIG. 5 is a cross-sectional view of a conventional paper transport roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Print head 2 Platen 3 Ink ribbon 4 Printing paper 5 Paper transport roller 6 Pinch roller 7 Roller shaft 8 Roller piece

Claims (7)

[Claims] 1. A paper comprising a resin core as a base, and roller pieces having rubber having excellent abrasion resistance press-fitted on an outer peripheral portion thereof, which are installed at arbitrary intervals on a metal roller shaft. Transport rollers. 2. Roller pieces having a core made of polyphenylene ether resin and press-fitted with ethylene propylene rubber having excellent wear resistance on the outer peripheral portion thereof are installed at an arbitrary interval on a metal roller shaft. Characteristic paper transport roller. 3. The sheet conveying roller according to claim 1, wherein said rubber thickness is 0.8 to 1.2 mm. 4. The sheet transport roller according to claim 1, wherein the roller is used for transporting a sheet of a dot impact printer. 5. The sheet conveying roller according to claim 1, wherein the roller is used for conveying a sheet of a type impact printer. 6. The sheet conveying roller according to claim 1, wherein the sheet conveying roller is used for conveying a sheet of an ink jet printer. 7. The sheet conveying roller according to claim 1, wherein the sheet conveying roller is used for conveying a sheet of a thermal printer.