JPH091776A - Printer - Google Patents

Abstract

PURPOSE: To facilitate high quality printing by improving positional precesion of an image printed on a surface of a work and its shape precision by a method wherein in order to give tension to an ink retaining means, the ink retaining means is energized parallel to a second direction from one end part of the fixed ink retaining means. CONSTITUTION: A screen 3 corresponding to a required image is prepared, both ends 3a, 3b of the screen 3 are respectively over all width wound round retention members 10a, 10b. One end part 3a of the screen together with the retention member 10a is fixed to a fixing member 4. Further, the other end 3b of the screen 3 together with the retention member 10b is fixed to a connecter 5. At that time the screen 3 is fixed under a state wherein a constant tension spring 12 is elongated to the screen 3 side, and uniform tension operates over the whole width of the screen by restoring force when the constant tension spring 12 contracts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus, and more particularly to a printing plate section for screen printing and a transfer head section for offset printing.

[0002]

2. Description of the Related Art Conventionally, various printing apparatuses have been used to print a desired image on a recording material (hereinafter referred to as a work). For example, in this printing device, a screen printing device that prints using a screen having a large number of through holes corresponding to an image, and a transfer such as a planographic printing plate, a letterpress printing plate, an intaglio printing plate and a work that alternately repeat contact and separation. There is an offset printing apparatus that prints using a blanket sheet fixed to the head portion.

FIG. 6 is a sectional view schematically showing a plate section of a screen printing apparatus which is an example of a conventional printing apparatus.
The plate section 50 of this printing apparatus has a screen 51 having a large number of through holes, and presses / slides the screen 51 to push the ink 52 placed on the back surface 51a of the screen from the through holes to the front surface 52b of the screen. A squeegee 53 to be put out, and a frame 54 for accommodating these and forming the plate portion 50
Having. The screen 51 is a slightly stretchable elastic member and is directly fixed to the ends 54a and 54b of the frame 54 with an adhesive. The squeegee 53
The screen 51 can be pressed and brought into contact with the work 55, which is a recording material, and can be moved between the end portions 54a and 54b of the frame. At the time of printing, by moving the squeegee 53 in the direction indicated by the arrow 56, the ink 52 is extruded to the front surface side 51a of the screen 51 and attached to the surface of the work 55.

However, since the screen 51 is directly fixed to the frame 54, if the squeegee 53 moves near the end 54a or 54b of the frame 54 during printing, excessive tension is generated on the screen 51. . On the other hand, when the squeegee 53 is located substantially in the middle of the ends 54a and 54b, that is, when it is located at the substantially central position of the screen 51, no excessive tension is generated on the screen 51. That is, the tension of the screen 51 is small at the substantially central position of the screen 51, and the screen 51 can easily contact the work 55, but the tension of the screen 51 becomes large on the end side of the screen 51, and the screen 5 has a large tension.
The screen 51 is significantly deformed in order to bring 1 into contact with the work 55. That is, when the tension acting on the screen 51 increases, the screen 51 is deformed, so that the positions of the many through holes provided in the screen 51 change. Therefore, the positional accuracy of the image line printed on the work 55 is reduced. Also, due to the deformation of the screen 51,
The shape of the through hole is deformed, and the shape accuracy of the printed image line is also reduced. Furthermore, when the squeegee 53 moves in the direction of the arrow 56, the screen 51 causes the work 5
5 are sequentially contacted and separated from each other, but at this time, due to the action of the adhesive force of the ink 52, the screen 51 causes the screen 51 to move in accordance with the magnitude of the tension generated in the screen 51.
Influence the situation away from. For this reason, the shape of the ink of the image line to be printed partially changes, and the accuracy of the image line shape decreases.

Further, the transfer head in the offset printing apparatus has a slightly stretchable blanket sheet, a press roll for pressing the blanket sheet against the plate and the work, and an end portion of the blanket sheet fixed with an adhesive. It has a frame. Therefore, at the time of printing, as in the case of the screen printing apparatus, an excessive tension is generated on the blanket sheet depending on the position of the press roll. Therefore, a part of the blanket sheet to which excessive tension is applied is significantly deformed, and the positional accuracy and the shape accuracy of the image line printed on the work are deteriorated.

In order to solve such a problem, a method of applying tension to one end of the screen with a cylinder or the like has been proposed. However, in the method of applying tension to one or several places of the end portion, the entire width of the screen is uniform. It is difficult to apply such tension, and there are drawbacks such as wrinkles.

[0007]

As described above, in the screen printing apparatus, the screen is pressed against the work by the squeegee, and contact and separation are repeated, but excessive tension is applied to the screen depending on the relative position of the frame and the squeegee. As a result, the screen is deformed and the dimensional accuracy of the pattern formed on the surface of the screen is reduced.
Occurrence of undulations on the screen surface due to changes in tension,
There is a problem that the shape accuracy and the position accuracy of the image line printed on the work change due to a change in the adhesion state of the ink to the work.

Further, in the offset printing apparatus, the blanket sheet is pressed against the work by the press roll, and contact and separation are repeated, but the same problem as in the case of the screen printing apparatus described above occurs.

Therefore, an object of the present invention is made in view of the above-mentioned circumstances, and it is possible to improve the positional accuracy and the shape accuracy of an image printed on the surface of a work to achieve high-quality printing. A printing device that enables the printing is provided.

[0010]

SUMMARY OF THE INVENTION The present invention has been made based on the above problems, and is an ink holding means which is formed in a sheet shape and holds ink for forming a desired image on a recording material, It extends in the first direction along the ink holding means, and in order to supply the ink to the recording material through the ink holding means, the ink holding means is pressed with a predetermined pressure in the first direction. A pressing unit that moves in a second direction that is orthogonal to the pressing unit, is fixed to one end of the ink holding unit over substantially the entire width in the first direction, and is fixed to apply tension to the ink holding unit. And a biasing unit that biases the ink holding unit in parallel to the second direction from the one end.

[0011]

According to the present invention, the one end of the ink holding means is fixed to the biasing means along substantially the entire width in the first direction. That is, the ink holding means is fixed to the urging means for applying a predetermined tension over the entire width of one end of the ink holding means.
The biasing means applies tension to the ink holding means in a direction parallel to the second direction in which the pressing means moves. Therefore, with the movement of the pressing unit, the tension applied to the ink holding unit is maintained uniform without generating an excessive tension on the ink holding unit. Therefore, undesired deformation of the ink holding means is prevented,
The positional accuracy and shape accuracy of the image printed on the recording material are improved, and high-quality printing is enabled.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, a screen printing apparatus, which is an example of a printing apparatus, will be described as a first embodiment of the present invention.

FIG. 1 is a diagram schematically showing a cross section of a plate portion of a screen printing apparatus. FIG. 2 is a perspective view schematically showing a plate section of the screen printing apparatus shown in FIG. That is, the printing plate unit 1 of the screen printing apparatus has a frame 2 made of a material such as aluminum, a screen 3 having a large number of through holes for forming a desired image, and one end 3a of the screen 3 over the entire width of the frame 2 A constant tension device 6 for connecting the fixing member 4 fixed to the end 2a of the frame 2 to the end 2b of the frame 2 via a connector 5 for applying a predetermined tension to the screen 3 and fixing the other end 3b of the screen 3 over the entire width. , And the work 7 as the recording material, the screen 3 is pressed against the work 7, and the ink 8 is applied to the screen 3.
Has a squeegee 9 extruded from the through hole.

The screen 3 is a sheet having a thickness of about 100 μm and is a kind of so-called stencil having a large number of through holes at predetermined positions. The fixing member 4 extends in the Y-axis direction, that is, parallel to the end 2a of the frame 2, and is fixed to the end 2a by screwing or the like. One end 3a of the screen 3 is wound around the holding member 10a over the entire width of the screen 3 defined in the Y-axis direction, and the holding member 10a is fixed to the fixing member 4 by screwing or the like to clamp the one end 3a. Is fixed to the fixing member 4. On the other hand, the other end 3b of the screen 3 has one end 3a
Similarly to the above, the entire width of the screen 3 defined in the Y-axis direction is wound around the holding member 10b, and the screen 3
Are fixed to the connector 5 while being uniformly stretched with a predetermined tension.

The constant tension device 6 includes a holder 11 extending in the Y-axis direction, a constant tension spring 12 obtained by bending a leaf spring made of an elastic member and then winding it in a cylindrical shape, and the constant tension spring 12. It has holding members 13a and 13b around which both ends 12a and 12b are respectively wound. The holder 11 extends parallel to the end 2b of the frame 2 and is fixed to the end 2b by screwing or the like.
Further, the holder 11 has a protruding portion 11a protruding from the end portion 2b of the frame 2 in the X-axis direction. Constant tension spring 12
Is formed in a cylindrical shape extending in the Y-axis direction.
The one end portion 12a of the constant tension spring 12 is wound around the holding member 13a over the entire width of the constant tension spring 12 defined in the Y-axis direction, and the holding member 13a is fixed to the connector 5 by screwing or the like to fix the one end portion 12a. It is fixed to the connector 5 by pinching. On the other hand, like the one end portion 12a, the other end portion 12b of the constant tension spring 12 is wound around the holding member 13b over the entire width of the constant tension spring 12 defined in the Y-axis direction and fixed to the protruding portion 11a of the holder 11. ing. Also, the other end 1 of the constant tension spring 12
The vicinity of 2b is in contact with the surface of the protrusion 11b. Further, the central axis O of the cylindrical constant tension spring 12 is located inside the end 11b of the protruding portion 11a of the holder 11, that is, on the end 2b side of the frame 2. Therefore, even when the force in the direction indicated by the arrow 14 acts, the constant tension spring 1
2 does not move up and down in the Z-axis direction. In the constant tension device 6 having such a configuration, even if the end portion 12a of the constant tension spring 12 is displaced in the direction of the arrow 14, the uniform tension is always applied to the entire width of the screen 3 and the entire surface of the screen 3 is applied. The applied tension is kept constant.

The squeegee 9 is provided so as to be movable between the fixing member 4 and the connector 5 in the direction of arrow 15, that is, in the direction parallel to the work 7. Next, the operation of the printing apparatus of the present invention will be described.

First, a screen 3 corresponding to a desired image is prepared, and both ends 3a and 3b of the screen 3 are respectively wound around the holding members 10a and 10b over the entire width. The one end 3a of this screen has a holding member 1
It is fixed to the fixing member 4 together with 0a. Further, the other end portion 3b of the screen 3 is fixed to the connector 5 together with the holding member 10b. At this time, the screen 3 has the constant tension spring 12
Is fixed in a state of being extended to the screen 3 side, and a uniform tension acts on the entire width of the screen by the restoring force when the constant tension spring 12 contracts.

Subsequently, after the ink 8 is placed on the back surface 3c of the screen 3, the squeegee 9 moves the screen 3 in the direction of the arrow 15 while pressing the screen 3 against the work 7. In this way, the ink 8 is introduced from the through hole to the surface 3 of the screen.
It is extruded into d and attached to the work 7. Even during this movement of the squeegee 9, the screen 3 is operated by the action of the constant tension device 6.
A uniform tension is applied to the entire surface of.

By repeating this operation, a fixed image is printed on a plurality of works. Thus, the screen 3 of the printing device in this embodiment
The constant tension device 6 constantly applies a predetermined tension in one direction, that is, the direction in which the constant tension spring 12 is restored, over the entire width of the squeegee 9 even if the squeegee 9 is moving.
Does not change and the screen 3 is not overly tensioned. Therefore, the screen is not deformed, and the positional accuracy of the image lines recorded on the work 7 is not impaired. Further, since a predetermined tension is applied to the screen 3, the screen 3 is not evenly separated from the surface of the work 7 and the shape accuracy of the drawing line is not impaired.

Next, an offset printing apparatus, which is an example of a printing apparatus, will be described as a second embodiment of the present invention. FIG. 3 is a diagram schematically showing a cross section of the transfer head portion of the offset printing apparatus. The same members as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

That is, the transfer head portion 20 of the offset printing apparatus has a frame 2 made of a material such as aluminum, a blanket sheet 21 for transferring a desired image from a plate to a work, and one end portion 21a of the blanket sheet 21 as a frame. A predetermined tension is applied to the fixing member 4 and the blanket sheet 21 that are fixed to the end portion 2a of 2,
It has a constant tension device 6 connected to the end 2b of the frame 2 via a connector 5 for fixing the other end 21b of the blanket sheet 21. A press roll (not shown) is also provided to press the blanket sheet 21.

The blanket sheet 21 comprises a surface layer 22 made of, for example, silicon rubber, and a metal sheet substrate 23 formed of a metal having a low coefficient of thermal expansion. The metal sheet substrate 23 used in this embodiment has a thickness of about 0.3.
mm.

Both ends 21 of the blanket sheet 21
Similar to the screen of the first embodiment, a and 21b are respectively wound around the holding members 10a and 10b over the entire width and fixed to the fixing member 4 and the connector 5. At this time, the blanket sheet 21 is fixed to the connector 5 with the constant tension spring 12 pulled out toward the connector 5 side and extended. Therefore, the blanket sheet 21 is kept in a state of being uniformly stretched with a predetermined tension over the entire width by the restoring force generated when the constant tension spring 12 contracts.

Next, the operation of the printing apparatus of the present invention will be described. First, a plate (not shown) such as a lithographic plate, a relief plate, or an intaglio plate of a desired image is prepared below the blanket sheet 21. A work (not shown) is prepared separately from this plate. Subsequently, the back surface 21 of the blanket sheet 21 is pressed while the press roller presses the blanket sheet 21.
Roll c. At this time, the blanket sheet 21 comes into contact with the plate, ink is drawn from the plate, and an ink image of a desired image is transferred to the surface 21d of the blanket sheet 21. Then, a work is prepared below the blanket sheet 21. By rolling while pressing the back surface 21c of the blanket sheet 21 with the press roller, the ink image comes into contact with the work, and the desired image is transferred to the work.

In this way, the blanket sheet 21 alternately contacts the plate and the work located therebelow, so that a certain image is printed on a plurality of works.
When the press roller rolls while pressing the blanket sheet 21, the action of the constant tension device 6 does not generate excessive tension on the blanket sheet 21. Therefore, since the blanket sheet 21 is not partially deformed, the positional accuracy of the image line recorded on the work is not deteriorated. Further, since the blanket sheet 21 is given a predetermined tension, the blanket sheet 2
1 is evenly separated from the surface of the work, and high-quality printing is possible without impairing the shape accuracy of the image line.

On the other hand, when the viscosity of the ink is high and the adhesion of the ink to the work is strong, a constant tension spring having a large tension is used. 4 and 5 are modified examples of the constant tension device used in the printing device of the present invention.

The constant tension device 30 shown in FIG.
Two leaf springs 31, 3 extending along the end 2b of the
2 and a cylindrical support member 33. One end 31 a of the leaf spring 31 is wound around the holding member 13 b and fixed to the holder 11. The other end 31b of the leaf spring 31
Is formed into a cylindrical shape, and the tip portion 31c thereof is
It is bent toward the inside of the cylinder. On the other hand, one end 32a of the leaf spring 32 is wound around the holding member 13a and fixed to the connector 5. The other end 3 of the leaf spring 32
2b is formed in a cylindrical shape along the other end 31b of the leaf spring 31, and a tip portion 32c thereof is bent toward the inside of the cylinder. The support member 33 is the frame 2
Have parallel groove portions 33a along the edges.

Two leaf springs 31 and 32 are wound along the outer surface of the support member 33, and the bent tip portions 31c and 32c of the two leaf springs 31 and 32 are inserted into the groove portion 33a. The support member 33 includes the leaf springs 31 and 32.
Sandwich. Further, the central axis O of the cylindrical support member 33 is inside the end portion 11b of the holder 11, that is, the protruding portion 11
Since it is located below a, the end portion 32a of the leaf spring 32 is
Is pulled in the direction of arrow 34, the constant tension device 30
It does not move up and down in a direction perpendicular to the direction in which is drawn. For this reason, the vertical shake of the screen 3 or the blanket sheet 21 is suppressed. Further, the constant tension device 30 can be used when strong tension is required because the leaf springs 31 and 32 have a simple shape and can be obtained by easily processing a thick plate.

The constant tension device 40 shown in FIG. 5 has two leaf springs 4 extending along the end 2b of the frame 2.
1, 42, a cylindrical support member 43, and two leaf springs 4
It has a member 44 for sandwiching 1, 42. One end 41 a of the leaf spring 41 is wound around the holding member 13 b and fixed to the holder 11. The other end 41b of the leaf spring 41 is
It is formed in a cylindrical shape, and its tip portion 41c is formed in a planar shape. On the other hand, one end 42a of the leaf spring 42
Is fixed to the connector 5 by being wound around the holding member 13a. The other end 42b of the leaf spring 42 is connected to the leaf spring 41.
It is formed in a cylindrical shape along the other end portion 41b, and its tip portion 42c is formed in a planar shape. The support member 43 is a recess 43 formed along the end of the frame 2.
a. The sandwiching members 44A and 44B fix the two leaf springs 41 and 42 to the support member 43 with screws 45.
The central axis O of the cylindrical support member 43 is located inside the end 11b of the holder 11, that is, below the protrusion 11a, as in the case of the constant tension device 30 shown in FIG. Therefore, even when the end portion 42a of the leaf spring 42 is pulled in the direction of the arrow 46, the constant tension device 40 does not move up and down in a direction perpendicular to the pulling direction. For this reason, the vertical shake of the screen 3 or the blanket sheet 21 is suppressed. Further, the constant tension device 40 can be used when strong tension is required because the leaf springs 41 and 42 have a simple shape and can be obtained by easily processing a thick plate.

By using the constant tension device as described above, it is possible to prevent a partial excessive tension from being applied to the screen and the blanket sheet, and the screen and the blanket sheet are not significantly deformed. Therefore, high-quality printing can be performed without impairing the positional accuracy and shape accuracy of the image recorded on the work. Further, since the tension applied to the screen and the blanket sheet is always kept at a predetermined value, the positional accuracy and shape accuracy of the image line recorded on the work can be maintained constant.

In the embodiment described above, the screen 3
The leaf springs 31, 32, 41, 42 having a width substantially equal to that of the blanket sheet 21 are connected to the screen 3 and the blanket sheet 21. You may connect. Further, although the present invention has been described with reference to the embodiments of the screen printing apparatus and the offset printing apparatus, it can be applied to other printing apparatuses.

[0032]

As described above, according to the printing apparatus of the present invention, one end of a sheet-shaped ink holding means such as a screen or a blanket sheet is fixed to the frame over the entire width, and the other end is the same. Since it is fixed to the constant tension device through the connector over the entire width,
A uniform tension is applied across the width of the ink holding means. Therefore, during printing, when the pressing means such as a squeegee or a press roll moves while pressing the ink holding means, excessive tension is not applied to the ink holding means. Therefore, the deformation of the ink holding unit is prevented, and the positional accuracy and shape accuracy of the image printed on the work are improved, so that high-quality printing is possible.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section of a plate portion of a screen printing apparatus which is an example of a printing apparatus of the present invention.

FIG. 2 is a perspective view schematically showing a printing plate section of the screen printing apparatus shown in FIG.

FIG. 3 is a diagram schematically showing a cross section of a transfer head portion of an offset printing apparatus which is an example of the printing apparatus of the present invention.

FIG. 4 is a modification of the urging means used in the printing apparatus of the present invention.

FIG. 5 is a modification of the urging means used in the printing apparatus of the present invention.

FIG. 6 is a diagram schematically showing a cross section of a plate portion of a screen printing apparatus which is an example of a conventional printing apparatus.

[Explanation of symbols]

1 ... Plate part 2 ... Frame 3 ... Screen 4 ... Fixing member 5 ... Connector 6 ... Constant tension device 7 ... Work piece 8 ... Ink 9 ... Squeegee 10a, 10b ... Holding member 11 ... Holder 12 ... Constant tension spring 13a, 13b ... Holding member 20
... Transfer head part 21 ... Blanket sheet 30 ... Constant tension device 31 ... Leaf spring 32 ... Leaf spring 33 ... Support member 40 ... Constant tension device 41 ... Leaf spring 42 ... Leaf spring 43 ... Support member 45 ... Screw

Claims (5)

[Claims] 1. An ink holding unit which is formed in a sheet shape and holds an ink for forming a desired image on a recording material; and an ink holding unit which extends in a first direction along the ink holding unit. Pressing means for moving ink in a second direction orthogonal to the first direction while pressing the ink holding means with a predetermined pressure in order to supply ink to the recording material via the holding means; Fixed to one end of the means along a first direction over substantially the entire width and biased parallel to the second direction from the one end of the fixed ink holding means to tension the ink holding means. A printing device comprising: 2. The urging means has a first plate spring portion, one end of which is fixed to the ink holding means along the first direction and the other end of which is formed in an arc shape, and one end of which is the first. A second plate spring part fixed to the outside along the direction and having the other end formed in an arc shape, and the other ends of the first and second plate spring parts are integrally formed. The printing apparatus according to claim 1, wherein the printing apparatus is a printing apparatus. 3. The biasing means has one end fixed to the ink holding means along the first direction and the other end having a first plate spring portion formed in an arc shape, and one end having a first A second plate spring part that is fixed to the outside along the direction and has the other end formed in an arc shape, and the other ends of the first and second plate spring parts are connected by a connecting member. The printing apparatus according to claim 1, wherein the printing apparatus is provided. 4. The ink holding means is a screen having a plurality of through holes and repeatedly contacting and separating from the surface of the recording material, and the pressing means is the side of the screen where the pressing means is located. 4. A squeegee movably formed in the second direction in order to push out the ink placed on the recording medium from the through hole to the side where the recording material is located. The printing device according to any one of the above. 5. The ink holding means is a blanket sheet that alternately repeats contact and separation with respect to the surface of a recording material and a plate formed into a desired image with ink, and the pressing means is the blanket. 4. The printing apparatus according to claim 1, wherein the printing roller is a press roll formed so as to be movable in the second direction while pressing the sheet toward the plate and the recording material.