JP2002226085A - Roll end member, sheet material carrying roll, and sheet carrying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problem in carrying the sheet that it is necessary to provide an encoder in order to accurately obtain images of high quality and the installation space thereof is large. SOLUTION: This sheet carrying roll has a sheet carrying part and a roll end member formed by integrally forming a roll drive input mechanism part with a rotation detecting pattern of the plastic magnetic material and fixed to the sheet carrying part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a sheet material transport roll for transporting a sheet material such as paper or plastic in an image forming apparatus.

[0002]

2. Description of the Related Art In image forming apparatuses such as various printers, electronic copiers, facsimile machines, and XY plotters, cassettes or the like are used to record various information including characters and figures on sheet materials such as paper and plastic. A transport device is provided which separates a large number of sheet materials stored in a stacked state one by one and feeds them into the apparatus main body, and transports the sheet materials to a recording area.

As a recording means system adopted for the image recording means of the image forming apparatus, there are an ink jet system, a wire dot system, a thermal system, a laser beam system and the like. As an example of these recording methods, an image forming apparatus of an ink jet method will be described with reference to FIGS. The ink jet head 11 mounted on the carriage 10 discharges ink and prints on the sheet material s according to image information. The carriage 10 is driven by a driving device (not shown) in a direction perpendicular to the feeding direction of the sheet material s using the carriage shaft 12 as a guide.
Reciprocating by By driving the energy generating means of the ink jet head 11 along with the movement of the carriage 10, ink is ejected onto the sheet material s to perform recording. The ejection of ink from the inkjet head 11 is performed while the sheet material s is stopped, and when the recording is completed, the sheet material s is conveyed for a fixed distance. The material s moves in the direction perpendicular to the feed direction and ejects ink according to image information. The means for conveying the sheet material s includes a sheet conveying roller 13 disposed on the back side of the sheet material s and a pinch roller 14 pressing the roller. The sheet conveying roller 13 is used to apply a conveying force to the sheet material s.
The motive power is transmitted from a drive source (various motors and the like) 15 to be driven to rotate. The pinch roller 14 is urged by the leaf spring 16 at both ends of the rotating shaft and presses the sheet conveying roller 13. An encoder 17 for detecting the rotational position of the sheet conveying roller 13 is provided on the axis of the sheet conveying roller 13.
Is attached. The shaft of the sheet conveying roller 13 is connected to the drive source 15 via an intermediate transmission device 18.

[0004] Here, the encoder is attached to accurately convey the sheet material over a predetermined distance.
In order to obtain more accurate image quality, it is used to control the rotation speed and stop position of a transport roller, a motor of a driving source, and the like. In Japanese Patent Application Laid-Open No. Hei 8-225239, a sensor and an encoder calculate the roller rotation speed from the number of rotations and the rotation angle of the roller, and use the result to control the motor voltage value or current value so as to obtain a target paper conveyance speed. Used. In Japanese Patent Application Laid-Open No. H11-254776, the position of a drive shaft is controlled by closed-loop feedback by an encoder in order to accurately perform a predetermined line feed of a sheet. However, the encoders used for these components use a shaft of a sheet conveying roll to attach another component. For this reason, the accuracy of sheet conveyance is reduced, and a separate installation space is absolutely necessary.

[0005]

In recent years, in particular, in recent years, downsizing and high performance of personal computers have required printers connected to these devices to be downsized and have high image quality. The demand for printers is also emerging. As one of the measures to meet such demands, the appearance of a space-saving encoder for performing accurate detection is desired. That is, an encoder that is highly accurate and minimizes the installation space leads to downsizing of the printer. An object of the present invention is to provide a high-precision sheet material conveying roll which has an encoder function and can be installed in a small space.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and the encoder can be easily manufactured by adding a magnetic encoder function to the transport roll itself. A roll end member having an encoder function capable of contributing to high precision and miniaturization, and a sheet material conveying roll using the same.

That is, the first invention of the present application is a roll end member characterized in that the roll drive input mechanism and the rotation detection pattern are integrally formed of a plastic magnet material.

[0008] A second invention of the present application is a roll end member fixed to the sheet conveying section, wherein the sheet conveying section, the roll drive input mechanism section, and the rotation detecting pattern are integrally formed of a plastic magnet material. And a conveying roll for conveying a sheet material.

In the present invention, the sheet conveying section comes into contact with the sheet and conveys the sheet along with the sheet by frictional force. A cylindrical body made of a metal material is used as the sheet conveying section, and a member (roll end member) made of a plastic magnet material integrally formed with a roll drive input mechanism and a rotation detection pattern is provided at the end of the roll. Fixed. The rotation detection pattern is formed by magnetizing the roll end member at a constant period (for example, a pitch of about 10 μm) in the circumferential direction.

Further, the inventor of the present invention has the greatest influence on the paper feeding accuracy and the image quality is the concentricity between the magnetic encoder unit for detecting rotation and the sheet conveying unit. It has been found that it is advantageous for the sheet transport portion to be substantially integral. In order to obtain a high concentricity, it is desirable to form the magnetic encoder section and the sheet conveying portion in one member, or to form the members separately from each other, and to perform the outer peripheral processing in one step after integrating them. Therefore, in the present invention, after the roll end member of the transporting roll is fixed to the sheet transporting section, at least a part thereof is precisely processed concentrically with the outer periphery of the sheet transporting section, and then magnetized there. It is preferable to form a rotation detection pattern. By applying such a process, the rotation of the roll is accurately detected, and the conveyance control of the sheet can be performed with high accuracy.

In the present invention, as a material for the plastic magnet, magnetic powder such as γ-iron oxide, Co-doped γ-iron oxide, Sr or Ba ferrite, CrO ² , FeCr, etc. has sufficient mechanical strength such as PPS, nylon 6, nylon 12, etc. A resin dispersed in a resin made of engineering plastics can be applied, and a roll drive gear and the like can be integrally formed together with a part to be an encoder by an injection molding method. For the purpose of the present invention, multi-pole magnetization is carried out after the isotropic molding without applying an orientation magnetic field for anisotropy during injection molding. As the material of the sheet conveying section, a cylindrical base made of a metal material is preferable. The magnetic properties of the plastic magnet are 4.5 kA / m or more in coercive force and 0.1 kA / m.
It is desirable to have a saturation magnetic flux density of 1T or more. Next, a magnetized pattern having a constant period (for example, a pitch of about 10 μm) is formed in a part of the roll end member in the circumferential direction. The cylindrical substrate may be hollow or solid. The hollow roll is light in weight and has good responsiveness in sheet material conveyance control. Since the solid roll has high rigidity, it is advantageous to increase the roundness of the roll and to reduce the warpage during conveyance.

In the present invention, the drive input mechanism of the roll end member can be a gear.

In the present invention, the roll end member is preferably magnetically isotropic.

In the present invention, the sheet conveying section has a cylindrical structure, and the roll end member can be fixed to the inner diameter of the sheet conveying section main body. With such a configuration, the weight can be effectively reduced. As a fixing method, it is desirable to use mechanical means such as press-fitting, caulking, or a combination of press-fitting and bonding.

According to the present invention, the roll end member may have a configuration in which the roll support shaft is also provided. With such a configuration, a rotation detection pattern, a roll drive input mechanism,
All of the roll support shafts can be integrated, and the number of components can be reduced.

In the present invention, an injection molding method is suitable for forming the roll end member.

In the present invention, an MR sensor or GMR sensor, which is a magnetoresistive element, is generally used as a magnetic sensor for detecting the magnetization pattern of the magnetic encoder of the plastic magnet.

In the present invention, it is preferable that at least a part of the roll surface of the sheet conveying section has a rough surface having an Rz of 3 μm or more. The reason why the surface is roughened is to provide a gripping force when the transport roll sandwiches and transports the sheet material with the pinch roll.

In the present invention, the means for imparting a predetermined surface roughness to the roll surface of the sheet conveying section includes a blasting or etching treatment, a dulling method for roughening by local heating of a laser, a thermal spraying method, and a ceramics method. A coating method, a machining method, a grindstone roll, a rubber roll, and the like are preferable. Since the magnetized pattern is preferably formed on a smooth surface, the surface roughening treatment is preferably performed by masking the portion where the magnetized pattern is formed. There are various blasting methods, but generally sand blast is often used.
Etching is performed by screen printing a resist resin in a dot pattern on the surface of the sheet conveying section, and then immersing the sheet conveying section in an etching solution (hydrochloric acid, sulfuric acid, nitric acid, etc.) to obtain a rough surface (which may be electrolytic etching). It is formed.
A stable roughened surface can also be formed by a dulling method using a heating mark formed by local heating by irradiation with a YAG laser or CO ² laser spot.

In a third aspect of the present invention, the conveying roll is rotated while pressing the sheet against a conveying roll of the sheet material having a fixed-period magnetization pattern on at least a part of the circumference of the roll. This is a sheet material conveyance method in which a rotation sensor pattern of a sheet material conveyance roll is detected by a magnetic sensor installed in proximity to or in contact with the magnetic pattern, and the rotation is controlled by a signal from the magnetic sensor.
The magnetization pattern formed on the transport roll is counted as a signal of a repetitive waveform, and the read signal indicates
It is possible to stop the motor of the drive source and the like, and thus control the rotation of the transport roll with high precision and stop it.

In the present invention, when a magnetized pattern having a constant period is provided on the circumference of the plastic magnet, the pitch can be changed depending on the diameter of the roll and the required stopping accuracy. When the roll diameter is small, for example, 7 mm, the pitch is naturally preferably small, and a pitch of about 10 μm is preferable.
However, if it is smaller than 10 μm, the detection by the magnetoresistive element may be erroneous, so that the pitch is usually preferably 10 μm or more, more preferably 40 μm or more, and still more preferably 80 μm or more.

[0022]

(Embodiment 1) An embodiment of the present invention will be described below. FIG. 1 is a schematic perspective view showing a use state of a main portion of a roll for conveying a sheet material according to an embodiment of the present invention, which is installed in a printer. In this embodiment,
Although the drive unit is not shown in the drawings, a drive means and a roll connecting means that is substantially the same as the conventional method shown in FIG. 4 is used. Reference numeral 1 denotes a roll for conveying the sheet material according to the present invention, which is a stainless steel cylindrical body having a diameter of 13 mm, and the sheet material conveying surface 3a has a rough surface of about 7 μm Rz by sandblasting, and conveys the sheet material s. The grip force at the time comes out. The roll end member 2 integrally formed by a non-oriented magnetic field injection molding method is an isotropic plastic magnet in which Sr ferrite magnetic powder is dispersed and contained by 80% by weight in a PPS resin binder, and is about 80 kA /
m and a magnetic flux density of 0.1T. Reference numeral 2a denotes a rotation detection pattern portion formed by magnetizing the roll end member 2 in the circumferential direction, and details of the magnetization are shown in FIG. Reference numeral 4 denotes an MR magnetoresistive element for detecting and counting the magnetized pattern 2, which is disposed close to or several hundred micrometers away from the rotation detection pattern 2a. 2b is a roll drive input mechanism (rotation transmission gear). In the present invention, all of the magnetized pattern forming portion 2a, the rotation transmission gear portion 2b, and the roll support shaft 2c are formed by the roll end member 2
And is press-fitted and fixed to the inner diameter of the sheet conveying section 3 by an injection molding method. Rotation transmission gear 2
b is connected to a drive source via an intermediate transmission device (not shown). Reference numeral 7 denotes a pinch roll, which serves to press the sheet s so that the sheet s is in close contact with the transport roll 1 when the sheet s is transported by the transport roll 1. Although not shown, the pinch roll 7 may be biased by a spring or the like at the shaft end of the pinch roll 7 in order to make the sheet material s more closely contact the transport roll 1.

In this embodiment, the rotation detecting pattern 2a, the roll drive input mechanism 2b, and the roll support shaft 2c are arranged in this order from the side of the sheet conveying section 3, but the order is arbitrary. When the roll support shaft 2c is not integrally formed of the same material as the roll end member 2, for example, a separately prepared roll support shaft is set in advance in an injection mold, and then a molten plastic magnet material is injected. It can be formed integrally with the roll end member 2. Alternatively, it may be fixed to the roll end member 2 by press-fitting and / or bonding or mechanical engagement means.

At the end of the sheet conveying roll 1 on the side where the roll end member 2 is not attached, a flange (not shown) having a supporting shaft is attached to the sheet conveying section 3 to support the supporting shaft with a bearing. . Alternatively, the outer peripheral surface of the end portion of the sheet conveying section 3 that is not roughened can be supported by a bearing.

FIG. 2A shows a roll end member 2 according to the present invention.
FIG. 4 is an enlarged view of a main part of a magnetized pattern 2a and a magnetoresistive element 4 formed in FIG. FIG. 2B is a sectional view taken along the line AA in FIG.
3 shows a cross section. In this embodiment, the roll end member 2 has a hollow structure. If sufficient mechanical strength and magnetic force can be obtained, a hollow structure is preferable in order to reduce the weight (reducing the rotational moment) and reduce the amount of material used. The magnetization pattern is such that N and S are repeatedly magnetized. In this embodiment, an example is shown in which N and S are respectively magnetized at 18 poles, but it is also possible to magnetize at a finer pitch as described above. It is.

The transporting roll 1 was incorporated into an ink jet printer at 12 sheets per minute and printed. As a result, both paper feeding accuracy and printing quality were good. At this time, the concentricity of the outer diameter of the roll body and the encoder portion was 8 μm.

FIG. 5 is a diagram showing a control system of a roll for conveying a sheet material. Arrows indicate the action of information or force, and indicate that they flow in the direction of the arrows. It indicates that the encoder is attached to the transport roll. Based on the image information, the printer interface exchanges information with control means of a driving source of the printer. The control means moves or stops the drive source according to the image information received from the printer interface. The conveyance of the sheet material is stopped according to the image information, and recording is performed during this time. When the recording is completed, the control means moves the driving source. The sheet conveying roller connected to the driving source rotates, and as shown in FIG. 1, the magnetized pattern applied to the surface of the sheet conveying roll is counted by a magnetoresistive element, and the count information is obtained. Feedback to the control means. The control means stops the driving source at a count number set in advance based on the count information. In this way, accurate conveyance of the sheet material is performed.

(Example 2) A sheet conveying roll having the same dimensions as in Example 1 was produced by the following method. SUS304 pipe with an outer diameter of 13.05 mm and an inner diameter of 10 mm (sheet transport unit 3)
The same roll end member 2 as in Example 1 was press-fitted to one end inner diameter, and the SUS304 pipe portion and plastic magnet portion were simultaneously subjected to centerless polishing to make the outer diameter 1
Finished to 3.00 mm. After that, S which comes into contact with the sheet material
Surface roughness R of US304 part by sandblasting
After the surface was roughened to z = 22 μm, the same magnetization as in Example 1 was performed on the plastic gnet portion. The same evaluation as in Example 1 was performed using this transport roll. As a result, both the paper feeding accuracy and the print quality were better than in Example 1. At this time, the concentricity of the outer diameter of the roll body and the encoder part is 4 μm
Met.

(Comparative Example 1) A roll end member 2 (encoder section) and a SUS304 sheet conveying main body were separately manufactured, and the outer diameter of each was finished to 13.00 mm. The magnetized roll end member 2 was pressed into and adhered to the sheet conveying section 3 to be integrated. When this was subjected to a print test evaluation in the same manner as in Example 1, the paper feeding accuracy was reduced, and moire-like print image quality was obtained. At this time, the concentricity of the outer diameter of the roll body and the encoder portion was 16 μm.

[0030]

According to the present invention, the magnetized pattern is directly applied to the sheet material conveying roll, and this can be detected by the magnetoresistive element. Therefore, the sheet material conveying roll is accurately rotated and stopped, and at the same time, Since the magnetized pattern, the roll drive portion, and the support shaft are integrated, the manufacturing process can be simplified, and the installation space can be made compact, which can contribute to the miniaturization of an image forming apparatus such as a printer.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part in which a sheet conveying roll according to an embodiment of the present invention is used.

FIGS. 2A and 2B are diagrams showing details of a magnetization pattern of a sheet material transport roll according to the present invention, wherein FIG. 2A is an enlarged view of a roll end member 2 of a sheet material transport roll 1, and FIG. a) A
-Rotation detection pattern 2a of roll end member 2 in section A
Is shown.

FIG. 3 is a sectional view schematically showing a conventional ink jet printer.

FIG. 4 is a plan view schematically showing a conventional ink jet printer.

FIG. 5 is a diagram showing a control system of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Conveyance roll of sheet material 2 Roll end member (made of a plastic magnet) 2a Rotation detection pattern 2b Roll drive input mechanism unit 2c Roll support shaft 3 Sheet conveyance unit 3a Sheet material conveyance surface 4 MR magnetoresistive element 7 Pinch Roll 10 Carriage 11 Inkjet head 12 Carriage shaft 13 Sheet transport roller 14 Pinch roller 15 Drive source 16 Leaf spring 17 Encoder 18 Intermediate transmission device s Sheet material

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H072 AA03 AA08 AA16 AA29 AB09 CA01 HA08 JA02 3F048 AA02 AA04 AA05 AA08 AB01 AB02 AB06 BB02 BB10 CA03 CB09 CC13 DA06 DC19 EA15 EB29 3F049 AA10 DA12 EA22 LA02 LB22 LA05 AA02 AA03 JA04 JA10 JB01 JC04 JD13

Claims (12)

[Claims] 1. A roll end member wherein a roll drive input mechanism and a rotation detection pattern are integrally formed of a plastic magnet material. 2. A sheet conveying section, a roll drive input mechanism section and a rotation detecting pattern are integrally formed of a plastic magnet material, and a roll end member fixed to the sheet conveying section. Roll for conveying the sheet material. 3. After the roll end member is fixed to the sheet conveying section, at least a part thereof is processed concentrically with the outer periphery of the sheet conveying section, and is then magnetized to form a rotation detection pattern. The roll for conveying a sheet material according to claim 2, which is formed. 4. The roll according to claim 2, wherein the roll drive input mechanism is a gear. 5. The roll for conveying a sheet material according to claim 2, wherein the plastic magnet material is magnetically isotropic. 6. The sheet material according to claim 2, wherein the sheet conveying section has a cylindrical structure, and the roll end member is fixed to an inner diameter of the sheet conveying section. Rolls for transport. 7. The roll according to claim 2, wherein the roll end member has a roll support shaft. 8. The roll according to claim 2, wherein the roll end member is formed by an injection molding method. 9. The sheet material conveying roll according to claim 2, wherein at least a part of the sheet conveying surface of the sheet conveying unit has a rough surface of Rz 3 μm or more. 10. The sheet material conveying roll according to claim 9, wherein the rough surface is formed by one of a blasting process, a dulling process by laser local heating, and an etching process. 11. The sheet material conveying roll according to claim 2 is rotated while being pressed against the sheet material, and a rotation detection pattern of the sheet material conveying roll is detected by a magnetic sensor, A method of conveying a sheet material, wherein the rotation is controlled by a signal from a magnetic sensor. 12. The sheet conveying method according to claim 11, wherein the signal from the magnetic sensor has a repetitive waveform, the number of repetitions is counted, and the rotation is controlled at a predetermined count.