JP2000044084A - Paper feeding mechanism for plotter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply secure the accuracy of a driving roller, and to make a paper feeding mechanism for a plotter compact, and to reduce production costs. SOLUTION: A printing medium is held between a driving roller and a pressing roller 18 so as to be carried on to the specified direction by the rotation of the driving roller, and printing and image forming are performed over to the printing medium by means of a print head. The driving roller is formed out of the plural number of short driving rollers 8 and 8, each of which is identical in diameter, and these plural short driving rollers 8 and 8 are connected with each other over an identical axis by an Oldham type coupling 16. The Oldham type coupling 16 is formed out of paired metallic discs 16a and 16b and a metallic intermediate disc 16c, the coupling part of an intermediate disc 16c is coated with teflon. Pilot pressure is applied to a space between each of the paired discs 16a and 16b and the intermediate disc 16c by means of a spring in such a way as to be closely attached to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed mechanism used for a plotter (printer) such as an ink jet type.

[0002]

2. Description of the Related Art JP-A-3-112696 and JP-A-Hei-4
Japanese Patent Application Laid-Open No. 80099 discloses a plotter of a type in which a sheet is sandwiched between a grid roller and a pressure roller to convey the sheet. Japanese Patent Application Laid-Open No. 5-229204 discloses an ink jet printer of the type in which a sheet is wound around a platen drum having a surface material of rubber, and the sheet is conveyed by pressing the sheet with a pressure roller. .

[0003]

If the drive roller of the plotter is formed in a long shape so as to correspond to paper of various sizes, there is a problem that the cost is increased. In order to solve this problem, a configuration is conceivable in which a plurality of short drive rollers are connected coaxially with a coupling, but this configuration can reduce the cost of the drive rollers, but uses a coupling. In addition, a problem arises in that the connection portion of each drive roller is twisted, and the drive roller cannot be controlled with high accuracy. This problem can be solved by using a coupling with high torsional rigidity, such as a bellows coupling that can perform high-precision positioning with little torsion.
There is a problem that these couplings are large and expensive. An object of the present invention is to solve the above problems.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention holds a print medium between a driving roller and a pressure roller and rotates the drive roller to convey the print medium in a predetermined direction. In a plotter for performing printing on a print medium by a print head, the drive roller is constituted by a plurality of short drive rollers (8) and (8) having the same diameter as each other, and the plurality of short drive rollers (8) are formed. ) And (8) are coaxially connected by an Oldham-type coupling (16), and the Oldham-type coupling (16) is connected to a pair of metal discs (16a).
(16b) and the pair of disks (16a) (16b)
And a metal intermediate disk (16c) joined by the projections (23) and (25) and the grooves (19) and (21), and the fitting portion of the intermediate disk (16c) is coated with Teflon. The pair of disks (16a) (16b) and the intermediate disk (1) of the Oldham coupling (16) are described.
6c), a preload acting between them in the direction of close contact is applied.

[0005]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In FIG.
(2) is a sheet mounting member (platen) of a large-sized ink jet plotter (printer), which is fixed to a lower substrate (4) of the plotter body via a bracket (not shown). A Y rail (not shown) is provided on an upper substrate (5) of the plotter main body, and an ink jet type print head (6) is movably mounted on the Y rail via a Y cursor. (8) denotes two drive rollers having the same diameter, each of which is made of a metal support shaft (10).
And a roller body (12) made of ceramic fixed concentrically thereto.

[0006] The ceramic surface of the roller body (12) is composed of a grit surface composed of countless protrusions, and the grit surface is configured so as not to damage a print medium such as paper and to have a high coefficient of friction. ing. Both ends of the support shaft (10) protrude outward from the center of both end surfaces of the roller body (12) coaxially for a predetermined length. The plurality of drive rollers (8) and (8) are arranged coaxially on the lower substrate (4), and the support shafts (10) and (10) at both ends of each drive roller (8) and (8) are connected to the substrate. The holders (14), (15), and (17) fixed to (4) are slidably and rotatably supported in the axial direction via bearings.

The support shaft (10) of one drive roller (8a)
And the other drive roller (8
The spindle (10) of b) is an Oldham-type coupling (1).
6). The coupling (1
The both side disks (16a) and (16b) and the intermediate disk (16c) of (6) have the same diameter as the roller body (12), and are coupled to the surfaces of the plurality of drive rollers (8) and (8) and the coupling (16). ) Are located on the same cylindrical peripheral surface.

The coupling (16) is composed of a pair of metal disks (16a) (16b) and a metal intermediate disk (16c). On both surfaces of the intermediate disk (16c), grooves (19) and (21) are formed at an angle of 90 degrees to each other, and both disks (16a) and (16b) correspond to the grooves (19) and (21). ) Are formed with convex portions (23) and (25), respectively. As shown in FIGS. 4 (B), the cross-sectional shape of the grooves (19) and (21) is formed in a U-shape, and tapered (T) is formed on both side surfaces of the grooves (19) and (21). Have been.

The projections (23) and (25) also have grooves (19).
Corresponding to (21), the cross-sectional shape is formed in a U-shape, and a round portion (R) is formed at the tip. The intermediate disk (16c) is coated with Teflon over the entire surface in order to prevent galling due to friction between metals. As shown in FIG. 1, support shafts (10) of a pair of adjacent drive rollers (8a) (8b) oppose each other.
(10) is assembled to the bearings (27) of the disks (16a) (16b) on both sides of the coupling (16) via fastening means, and the disks (16a) on both sides are assembled.
The protrusions (23) and (25) of (16b) are fitted into the grooves (19) and (21) of the intermediate disk (16c).

The other end of the support shaft (10) of the drive roller (8a) is connected to one end of the drive shaft (34) via a coupling (29) having the same structure as the coupling (16). The drive shaft (34) includes the support shafts (10) and (10).
A plate member (36) fixed to a plotter substrate (4) and a holding member (15) are rotatably supported so as not to shift leftward in FIG. ing. A board (38) is fixed to one of the support shafts (10) of the drive roller (8b).
A thrust washer or thrust bearing (40) is arranged in contact.

A plate (42) fixed to the substrate (4) has a shaft (44) protruding therefrom, and a preload spring (46) is attached to the shaft (44). The preload spring (46) is a plate member (4
It is in pressure contact with the thrust bearing (40) with 2) as a fulcrum. The support shaft (10) is urged leftward in FIG. 1 by the pressing force of the preload spring (46), and the grooves (19) and (21) of each coupling (16) and (29) and the convex portion. (2
3) and (25) are in close contact with each other, so that backlash of the support shafts (10) and (10) of the drive rollers (8) and (8) is removed.

Reference numeral (18) denotes a pressure roller, and a plurality of pressure rollers are arranged at appropriate positions on the drive rollers (8) and (8), and are each rotatably supported by a swing arm (20). I have. The swing arm (20) is rotatably supported on a shaft (24) by a bracket (22) fixed to the substrate (5) of the plotter body, and is supported by a spring (26) in FIG.
Energized clockwise. The drive roller (8)
(8) Each of the pressure rollers (18) on the upper surface of the spring (26)
The roller (12) of the drive roller (8) is pressed against the sheet (28) on the sheet placing member (2) by force. The drive shaft (34) is controlled by a controller via a power transmission mechanism (30) including a belt and a belt pulley, etc.
It is connected to.

In the above construction, the driving roller (8) is driven by the motor (32) controlled by the controller.
When (8) is driven to rotate in the paper transport direction, the paper (28) sandwiched on both sides and the intermediate portion by the drive rollers (8) and (8) and the pressure roller (18) is placed on the paper It moves in a predetermined direction on the member (2). On the other hand, under the control of the controller, the print head (6) is reciprocated in the direction (scanning direction) across the sheet (28) along the Y rail,
The print head (16) performs printing on a sheet (28).

In the above embodiment, the driving roller (8)
The surface of (8) does not enter the paper (28), so that the paper (28) is not damaged. Drive roller (8)
In (8), the entire width of the paper (28) can be covered by the roller body (12), and both sides in the width direction of the paper and the intermediate portion thereof can be pressed by the plurality of pressure rollers (18). it can. Therefore, even if there is no vacuum fan, the paper (28)
Of paper (28) can be fed accurately. In addition, one pressing roller (18)
However, since the pressure on the drive rollers (8) and (8) may be weak, a large strength is not required for the pressure roller (18).

In the above embodiment, the pressure roller portion,
A mechanism for moving the grid roller and winding the paper around the platen drum is unnecessary, and the mechanism is correspondingly simplified. Further, the roller body (12) of the drive rollers (8) and (8) may have the same diameter as that of the conventional grid roller, so that the weight can be reduced. As long as the driving rollers (8) and (8) are accurate one by one, a plurality of driving rollers having the same accuracy may be combined, and when one long driving roller is manufactured and assembled with high precision. The yield can be dramatically improved as compared with the case of That is, each drive roller (8) (8)
Is short, so accuracy can be easily secured.

In this embodiment, the driving roller (8)
In (8), two pieces are connected, but the number is not particularly limited to two pieces. Further, the pressure roller (18) may be arranged on the coupling (16). Further, the roller body (12) of the drive rollers (8) and (8) is not particularly limited to the ceramic roller, but is a high friction material that does not damage the paper, such as a hard rubber roller and a thermal spray pulley. , Rollers with small projections formed by etching, etc.
Rollers of various materials can be used. In this embodiment, since the intermediate disk (16c) of the couplings (16) and (29) is made of metal, the torsional rigidity is high, and the rotation of the drive rollers (8) and (8) can be controlled with high accuracy.

[0017]

As described above, according to the present invention, since a plurality of short drive rollers are connected by a coupling, the roller diameter can be reduced, and the size and cost of the apparatus can be reduced. In addition, if the accuracy of each drive roller is high, it is only necessary to combine the same accuracy with a small number, so that the yield becomes better and the accuracy of the drive roller can be easily secured. Further, by changing the number of drive rollers to be connected, a paper feed mechanism corresponding to various paper sizes can be configured, and even if the number of drive rollers is increased, rotation control can be performed with high accuracy. And so on.

[Brief description of the drawings]

FIG. 1 is a plan view of a main part of the present invention.

FIG. 2 is an explanatory diagram of an Oldham type coupling.

FIG. 3 is a front view of a main part of the present invention.

FIG. 4 is a side view of a main part of the present invention.

[Explanation of symbols]

 2 Paper placing member 4 Substrate 5 Substrate 6 Print head 8 Drive roller 10 Support shaft 12 Roller body 14 Bearing 15 Holder 16 Coupling 16a Disk 16b Disk 16c Intermediate disk 17 Holder 18 Pressure roller 19 Groove 20 Oscillating arm 21 Groove 22 Bracket 23 Convex part 24 Shaft 25 Convex part 26 Spring 27 Bearing part 28 Paper 29 Coupling 30 Power transmission mechanism 32 Stepping motor 34 Drive shaft 36 Plate member 38 Board body 40 Thrust bearing 42 Plate member 44 Shaft body 46 Pressurizing spring

Claims (2)

[Claims] 1. A plotter in which a print medium is sandwiched between a drive roller and a pressure roller, and the drive roller is rotated to convey the print medium in a predetermined direction, while printing is performed on the print medium by a print head. , The driving roller is constituted by a plurality of short driving rollers (8) and (8) having the same diameter, and the plurality of short driving rollers (8) and (8) are coaxially and Oldham-type coupling (16). ) To connect the Oldham-type coupling (16) to a pair of metal discs (16a).
(16b) and the pair of disks (16a) (16b)
And a metal intermediate disk (16c) joined by the convex portions (23) and (25) and the grooves (19) and (21), and a fitting portion of the intermediate disk (16c) is coated with Teflon. A paper feed mechanism, characterized in that: 2. A preload acting between the pair of discs (16a) (16b) and the intermediate disc (16c) of the Oldham-type coupling (16) in a direction in which they are in close contact with each other. Paper feed mechanism of the plotter described in the above.