U.S. patent application number 10/228188 was filed with the patent office on 2002-12-26 for screen printer and a screen printing method.
This patent application is currently assigned to Micro-Tec Company, Ltd.. Invention is credited to Sano, Yasushi, Tanaka, Osamu.
Application Number | 20020195007 10/228188 |
Document ID | / |
Family ID | 26338566 |
Filed Date | 2002-12-26 |
United States Patent
Application |
20020195007 |
Kind Code |
A1 |
Sano, Yasushi ; et
al. |
December 26, 2002 |
Screen printer and a screen printing method
Abstract
Screen printing is performed by using a pressure squeegee, a
main squeegee, and a scraper squeegee. Since a screen is pressed by
the pressure squeegee in advance, an angle between the main
squeegee and the screen is kept constant. After printing is
finished by the main squeegee, the scraper squeegee scrapes a
remaining ink.
Inventors: |
Sano, Yasushi; (Chiba,
JP) ; Tanaka, Osamu; (Niigata, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Micro-Tec Company, Ltd.
Urayasu-shi
JP
|
Family ID: |
26338566 |
Appl. No.: |
10/228188 |
Filed: |
August 27, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10228188 |
Aug 27, 2002 |
|
|
|
09473057 |
Dec 28, 1999 |
|
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Current U.S.
Class: |
101/123 |
Current CPC
Class: |
B41F 15/46 20130101;
H05K 3/1233 20130101 |
Class at
Publication: |
101/123 |
International
Class: |
B41L 013/18; B05C
017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 1999 |
JP |
HEI 11-004741 |
Mar 15, 1999 |
JP |
HEI 11-069176 |
Claims
What is claimed is:
1. A screen printer for performing screen printing on a work by
using a squeegee, comprising: a main squeegee for performing screen
printing; and a supplementary squeegee for supplementing screen
printing by the main squeegee during screen printing by the main
squeegee.
2. The screen printer of claim 1, wherein the main squeegee is
pressed on a screen in a determined angle, wherein the
supplementary squeegee is pressed on the screen in an angle
exceeding the determined angle.
3. The screen printer of claim 1, wherein the supplementary
squeegee is provided ahead of the main squeegee in a printing
direction; wherein the supplementary squeegee is a pressure
squeegee for pressing the screen on the work.
4. The screen printer of claim 3 further comprising a scraper
attached at one of a place between the main squeegee and the
pressure squeegee and a place ahead of the main squeegee and the
pressure squeegee in the printing direction.
5. The screen printer of claim 4, wherein the pressure squeegee is
unified with one of the scraper and the main squeegee.
6. The screen printer of claim 1, wherein the supplementary
squeegee is provided behind the main squeegee in a printing
direction, wherein the supplementary squeegee is a scraper squeegee
for scraping an ink on a screen.
7. The screen printer of claim 6, wherein the scraper squeegee is
unified with the main squeegee.
8. A screen printer comprising two squeegees, wherein the two
squeegees are used together successively to print a determined area
on a screen for one stroke.
9. A screen printing method for a screen printer comprising a main
squeegee and a supplementary squeegee comprising: performing screen
printing by moving of the main squeegee in a printing direction
with pressing a screen; and moving of the supplementary squeegee in
the printing direction with pressing the screen by keeping a
determined distance from the main squeegee in the printing
direction during screen printing by the main squeegee.
10. The screen printer of claim 3, wherein the pressure squeegee is
a pair of squeegees provided outside of a printing pattern of
screen printing.
11. A screen printer for performing screen printing on a work by
using a squeegee, comprising: a main squeegee for performing screen
printing; and a pressure unit provided ahead in a printing
direction during screen printing by the main squeegee for pressing
a screen against the work.
12. The screen printer of claim 11, wherein the pressure unit is a
roller for rotating on the screen.
13. The screen printer of claim 12, wherein the roller is a pair of
rollers provided outside of a printing pattern of screen
printing.
14. The screen printer of claim 11, wherein the pressure unit is
unified with a scraper.
15. A screen printing method for a screen printer having a main
squeegee and a pressure unit, comprising: performing screen
printing by moving the main squeegee in a printing direction with
pressing a screen; and moving the pressure unit in the printing
direction with pressing the screen by keeping a determined distance
in the printing direction from the main squeegee during screen
printing by the main squeegee.
16. A screen printer for performing screen printing, comprising a
first squeegee and a second squeegee for moving forward and
backward, wherein the first squeegee is a pressure squeegee for
pressing the screen and the second squeegee is a main squeegee for
performing screen printing in the forward movement, wherein the
second squeegee is the pressure squeegee for pressing the screen
and the first squeegee is the main squeegee for performing screen
printing in the backward movement.
17. The screen printer of claim 16 further comprising a rotary unit
for rotating the first and second squeegees and changing angles of
the first and second squeegees against the screen.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a screen printer and its screen
printing method. Particularly, this invention relates to the screen
printer using a plurality of squeegees. This invention also relates
to the screen printer using a pressure unit for pressing a
screen.
[0003] 2. Description of the Related Art
[0004] FIG. 12 illustrates a perspective view of the screen
printer. FIG. 13 illustrates a schematic side view of the screen
printer. FIG. 14 illustrates a schematic top view of the screen
printer.
[0005] In FIG. 12, a screen printer 101, a base of the screen
printer 102, a table 103 which is attached for allowing movement, a
guide rail 104 for guiding the movement of the table, an operation
box 105 of the screen printer, an operation switch 107 attached to
the operation box, and a printing unit 109 for performing screen
printing on a work placed on the table 103 are illustrated. In
FIGS. 13 and 14, a work 110 placed on the table 103, a screen plate
200, a screen frame 1 of the screen plate 200, and a screen 201
affixed to the screen plate 200 are illustrated. A slider 106 for
holding a squeegee 111 and a scraper (not illustrated) slides in
directions of arrow A and arrow D, and a slide base 108 slides the
slider 106.
[0006] The table 103 is attached for allowing left and right
sliding along the guide rail 104 provided on the base 102. When the
table 103 moves under the printing unit 109, the table 103 is
stopped by a stopper (not illustrated), and the printing unit 109
performs screen printing on the work 110.
[0007] FIG. 15 illustrate an example of the screen plate 200.
[0008] The screen plate 200 for a combination screen is illustrated
in FIG. 15.
[0009] In FIG. 15, the screen frame 1, a support screen 2, a print
screen 3, and a joint part 4 of the support screen and the print
screen are illustrated. The screen 201 includes the support screen
2, the print screen 3, and the joint part 4.
[0010] FIG. 16 illustrates a front surface of the print screen
3.
[0011] FIG. 17 illustrates a back surface of the print screen
3.
[0012] In FIGS. 16 and 17, a screen-mesh 30, and an emulsion 31
provided on a back of the screen-mesh 30 are illustrated. An
opening 32 is provided in the emulsion 31. The opening 32 is
provided for generating a print image. When an ink (paste) passes
through the opening and sticks to the work 110, screen printing is
performed on the work.
[0013] FIGS. 18 and 19 show cross-sectional views at X-X part of
the screen printer illustrated in FIG. 14. A squeegee holder 120
and a scraper holder 320 are attached to the slider 106 for
allowing up and down movement by a mechanism which is not
illustrated. In FIG. 18, the slider 106 is moving in the direction
of arrow A, and the squeegee 111 is pushed down in the direction of
arrow B. Printing is performed on the work 110 by using an ink 51.
The scraper holder 320 holds a scraper 311, and the scraper holder
is moved up in a direction of arrow C during a printing operation
by the squeegee. When printing is performed by using the squeegee
111, printing is performed with a high pressure. As illustrated in
FIG. 18, the screen is pressed by a pressure applied to the
squeegee at a point R in which the squeegee and the screen contact
each other. When the squeegee moves, the point R moves on the
surface of the screen.
[0014] In case of FIG. 19, the slider moves in a direction of arrow
D. When the slider moves in the direction of arrow D, the squeegee
holder 120 is pulled up in a direction of arrow E. At the same
time, the scraper holder 320 is pushed down in a direction of arrow
F, and the scraper 311 moves on the surface of the screen in
contacting with the screen 201. The scraper 311 has a function for
pushing the ink 51, which has been moved to a right side of FIG. 19
by the squeegee 111, back to a left side of FIG. 19. The scraper
311 also has a function for re-coating the surface of the screen
evenly with the ink after printing is performed by the squeegee
111.
[0015] The screen printer performs screen printing by moving the
squeegee 111 in the direction of arrow A as illustrated in FIG. 18.
As illustrated in FIG. 19, when the slider is moved in the
direction of arrow D, the ink is returned, and the surface of the
screen is evenly re-coated with the ink.
[0016] FIG. 20 illustrates a sectional view of the screen in case
that the squeegee 111 in FIG. 18 has performed printing on the work
110. The ink 51 passes through the opening 32 of the emulsion
provided on the back side of the screen-mesh, and sticks to the
work 110. Since the squeegee 111 is made of an elastic material,
e.g., urethane rubber, etc., when the squeegee 111 has passed, the
ink 51 on the surface of the screen is evenly scraped.
[0017] In FIG. 21, the scraper 311 returns the ink. The scraper 311
is made of a metal, e.g., stainless, etc. The scraper includes a
taper part 312 at an end, and contacts with the surface of the
screen at point Q. Since the scraper 311 is made of the metal,
e.g., stainless, etc., when the scraper 311 has passed, the surface
of the screen is evenly coated with the ink 51. In this way, an
evenly coated condition is generated. Therefore, next printing can
be performed evenly by the squeegee 111.
[0018] FIG. 22 illustrates the printing unit 109 in a printing
state. The screen 201 is evenly coated with the ink 51.
[0019] (a) of FIG. 22 illustrates a state before starting printing.
In (b) of FIG. 22, a pressure P is applied to the squeegee 111, and
printing is started. In (c) of FIG. 22, patterns 52, 53 and 54 have
been printed on the work 110 from patterns which are generated on
the screen 201 in advance. (d) of FIG. 22 illustrates a time of
completing printing. During printing in (b)-(d) of FIG. 22, the
pressure P applied to the squeegee 111 is constant as shown in (e)
of FIG. 22.
[0020] When printing is performed as illustrated in FIG. 22, a
height H1 of the pattern 52 and a height H2 of the pattern 54
illustrated in (d) of FIG. 22 may differ. Even though the screen
201 is tightly stretched over the screen frame 1, angles vary in
positions on the screen 201. Therefore, even if the constant
pressure P is applied downward during printing, there is a
possibility that a printed pattern may be spread forward in some
printing position. Hence, such problems like uneven thickness of
the ink on the work 110 and uneven printing have to be solved.
[0021] As shown in FIG. 22, angles .alpha., .beta., and .gamma.
between the screen 201 and the work 110 change during printing
(.alpha.<.beta.<.gamma.). Since the angles between the screen
201 and the work 110 vary in printing positions, there are solving
problems such as uneven thickness of the ink on the work 110 and
uneven printing.
[0022] FIG. 23 illustrates a method for solving the above-stated
uneven thickness of the ink.
[0023] In FIG. 23, during printing, the screen plate 200 is lifted
up in a direction of arrow X by using a detaching apparatus (plate
detaching apparatus) which is not illustrated. By detaching the
screen plate 200 from a side in which printing is finished, changes
in a tension in the positions on the screen 201 are intended to be
ignored. Consequently, the height H1 of the pattern 52 printed at
an edge area of the work 110 and the height H2 of the pattern 54
printed at a center of the work 110 can become almost equal.
[0024] However, according to the method of lifting one side of the
screen plate 200 as illustrated in FIG. 23, an excessive pressure
is applied to the screen plate 200. As a result, printing patterns
provided on the screen 201 might be shifted, and a durability of
the screen plate 200 might be reduced.
[0025] FIG. 24 illustrates a screen printer with two squeegees
according to the related art.
[0026] In (a) of FIG. 24, printing is performed by using the
squeegee 111. In (b) of FIG. 24, printing is performed by using a
squeegee 112.
[0027] The screen printer in FIG. 24 can print in both directions
of arrows A and D. After printing is performed in (a) of FIG. 24,
the work 110 is taken out, and another work 110 is put in. Then,
printing is performed in (b) of FIG. 24. By repeating operations in
(a) and (b) of FIG. 24, printing can be performed in a higher
speed.
[0028] FIG. 25 also illustrates screen printing by using two
squeegees.
[0029] Squeegees 113 and 114 are arranged in a straight line. The
screen printer as illustrated in FIG. 25 is used in case that an
area between the squeegees 113 and 114 should not be printed or can
not be printed due to roughness on the work.
[0030] FIGS. 24 and 25 illustrate the screen printer using two
squeegees. However, as stated, no consideration is made for
printing evenly on the work.
SUMMARY OF THE INVENTION
[0031] It is an object of a preferred embodiment of this invention
to provide a screen printer for printing evenly on a work.
Particularly, it is an object of a preferred embodiment of this
invention to provide a screen printer for printing in higher
quality by using a plurality of squeegees.
[0032] According to one aspect of this invention, a screen printer
for performing screen printing on a work by using a squeegee
includes a main squeegee for performing screen printing and a
supplementary squeegee for supplementing screen printing by the
main squeegee during screen printing by the main squeegee.
[0033] According to another aspect of this invention, a screen
printer includes two squeegees, and the two squeegees are used
together successively to print a determined area on a screen for
one stroke.
[0034] According to another aspect of this invention, a screen
printing method for a screen printer which has a main squeegee and
a supplementary squeegee includes a step of performing screen
printing by moving of the main squeegee in a printing direction
with pressing a screen and a step of moving of the supplementary
squeegee in the printing direction with pressing the screen by
keeping a determined distance from the main squeegee in the
printing direction during screen printing by the main squeegee.
[0035] According to another aspect of this invention, a screen
printer for performing screen printing on a work by using a
squeegee includes a main squeegee for performing screen printing
and a pressure unit provided ahead in a printing direction during
screen printing by the main squeegee for pressing a screen against
the work.
[0036] According to another aspect of this invention, a screen
printing method for a screen printer which has a main squeegee and
a pressure unit includes a step of performing screen printing by
moving the main squeegee in a printing direction with pressing a
screen and a step of moving the pressure unit in the printing
direction with pressing the screen by keeping a determined distance
in the printing direction from the main squeegee during screen
printing by the main squeegee.
[0037] According to another aspect of this invention, a screen
printer for performing screen printing includes a first squeegee
and a second squeegee for moving forward and backward. The first
squeegee is a pressure squeegee for pressing the screen and the
second squeegee is a main squeegee for performing screen printing
in the forward movement, and the second squeegee is the pressure
squeegee for pressing the screen and the first squeegee is the main
squeegee for performing screen printing in the backward
movement.
[0038] Further features and applications of the present invention
will become apparent from the detailed description given
hereinafter. However, it should be understood that the detailed
description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration
only, since various changes and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
[0039] Other objects features, and advantages of the invention will
be apparent from the following description when taken in
conjunction with the accompany drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] FIG. 1 illustrates a printing state of a screen printer
according to this invention;
[0041] FIG. 2 illustrates a printing state of the screen printer
according to this invention;
[0042] FIG. 3 illustrates a printing state of the screen printer
according to this invention;
[0043] FIG. 4 illustrates a printing state of the screen printer
according to this invention;
[0044] FIG. 5 illustrates a printing state of the screen printer
according to this invention;
[0045] FIG. 6 shows a flow chart of operations of the screen
printer according to this invention;
[0046] FIG. 7 illustrates a squeegee unified with the screen
printer according to this invention;
[0047] FIG. 8 illustrates a squeegee which can move vertically
against a scraper in the screen printer according to this
invention;
[0048] FIG. 9 illustrates squeegees which can move vertically
together in the screen printer according to this invention;
[0049] FIG. 10 illustrates squeegees which can move vertically
together in the screen printer according to this invention;
[0050] FIG. 11 illustrates squeegees which can move vertically
together in the screen printer according to this invention;
[0051] FIG. 12 illustrates a perspective view of the screen printer
according to the related art;
[0052] FIG. 13 illustrates a schematic front view of the screen
printer according to the related art;
[0053] FIG. 14 illustrates a schematic top view of the screen
printer according to the related art;
[0054] FIG. 15 illustrates a perspective view of the screen plate
according to the related art;
[0055] FIG. 16 illustrates a magnified view of a front surface of a
screen according to the related art;
[0056] FIG. 17 illustrates a magnified view of a back surface of
the screen according to the related art;
[0057] FIG. 18 illustrates an operation of screen printing
according to the related art;
[0058] FIG. 19 illustrates an operation of a scraper according to
the related art;
[0059] FIG. 20 shows an explanatory chart of the operation of
screen printing according to the related art;
[0060] FIG. 21 shows an explanatory chart of the operation of the
scraper according to the related art;
[0061] FIG. 22 illustrates problems in the screen printer according
to the related art;
[0062] FIG. 23 illustrates problems in the screen printer according
to the related art;
[0063] FIG. 24 illustrates a screen printer with two squeegees
according to the related art;
[0064] FIG. 25 illustrates the screen printer with two squeegees
according to the related art;
[0065] FIG. 26 illustrates a front view of a pressure squeegee 61
according to this invention;
[0066] FIG. 27 illustrates a top view of the pressure squeegee 61
and a main squeegee 63;
[0067] FIG. 28 illustrates a front view of the pressure squeegee 61
according to this invention;
[0068] FIG. 29 illustrates a top view of the pressure squeegee 61
and the main squeegee 63 according to this invention;
[0069] FIG. 30 illustrates a printing state of the screen printer
using a pressure roller 70 according to this invention;
[0070] FIG. 31 illustrates a printing state of the screen printer
using the pressure roller 70 according to this invention;
[0071] FIG. 32 illustrates a front view of the pressure roller 70
according to this invention;
[0072] FIG. 33 illustrates a top view of the pressure roller 70 and
the main squeegee 63 according to this invention;
[0073] FIG. 34 illustrates a front view of a right pressure roller
71 and a left pressure roller 72 according to this invention;
[0074] FIG. 35 illustrates a top view of the right pressure roller
71, left pressure roller 72 and main squeegee 63 according to this
invention;
[0075] FIG. 36 illustrates a front view of the right pressure
roller 71 and the left pressure roller 72 according to this
invention;
[0076] FIG. 37 illustrates a top view of the right pressure roller
71, left pressure roller 72, and main squeegee 63 according to this
invention;
[0077] FIG. 38 illustrates another example of the pressure roller
70, right pressure roller 71, and left pressure roller 72 according
to this invention;
[0078] FIG. 39 illustrates the right pressure roller 71 and left
pressure roller 72 which can slide according to this invention;
[0079] FIG. 40 illustrates the pressure roller 70 which can move
vertically against the scraper in the screen printer according to
this invention;
[0080] FIG. 41 illustrates the pressure roller 70 which can move
vertically together according to this invention;
[0081] FIG. 42 illustrates the pressure roller 70 which can move
vertically together according to this invention;
[0082] FIG. 43 illustrates a printing method using two squeegees
according to this invention;
[0083] FIG. 44 illustrates a printing state of the screen printer
according to this invention;
[0084] FIG. 45 illustrates a printing state of the screen printer
according to this invention;
[0085] FIG. 46 illustrates the squeegees which can move vertically
together according to this invention;
[0086] FIG. 47 illustrates the squeegees which can move vertically
together according to this invention;
[0087] FIG. 48 illustrates the squeegees which can move vertically
against the main squeegee in the screen printer according to this
invention;
[0088] FIG. 49 illustrates a top view of the pressure squeegee 61
and main squeegee 63 according to this invention;
[0089] FIG. 50 illustrates a leakage of the paste in the
"off-contact printing method";
[0090] FIG. 51 illustrates squeezing and detaching of the mask in
the "on-contact printing method";
[0091] FIG. 52 illustrates a configuration of a pre-contact
squeegee;
[0092] FIG. 53 illustrates a configuration of the pre-contact
squeegee;
[0093] FIG. 54 illustrates a condition of the screen and the work
when the pre-contact squeegee is placed downward;
[0094] FIG. 55 illustrates a deposition mechanism of the paste;
[0095] FIG. 56 illustrates the deposition force of the paste and
the condition of printing;
[0096] FIG. 57 illustrates a plasma display panel in phosphor
printing;
[0097] FIG. 58 illustrates a relationship of the screen and the
barrier ribs during the phosphor printing;
[0098] FIG. 59 illustrates a relationship of the screen, squeegee,
and barrier ribs during the phosphor printing and the leakage of
the paste;
[0099] FIG. 60 illustrates a configuration of a two-blade squeegee
in Embodiment 8; and
[0100] FIG. 61 illustrates an actual phosphor printing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0101] Embodiment 1.
[0102] FIGS. 1-5 illustrate printing operations by the screen
printer according to this invention.
[0103] FIG. 6 shows a flow chart of the printing operation.
[0104] In FIG. 1, the slider 106 starts forward movement (in a
direction of arrow A). The direction of arrow A is a direction of
printing (step S11). Then, a pressure squeegee 61 moves down from
the slider 106 (step S12).
[0105] In FIG. 2, a main squeegee 63 moves down (step S13).
[0106] In FIG. 3, a scraper squeegee 65 moves down (step S14). In a
state illustrated in FIG. 3, printing is continued in the direction
of arrow A (step S15).
[0107] In FIG. 4, the pressure squeegee 61 moves up (step S16).
Then, the main squeegee 63 moves up (step S17), and the scraper
squeegee 65 moves up (step S18). In this way, printing is finished,
and the slider 106 finishes its forward movement (step S19). Steps
S11-S19 are called as one stroke.
[0108] Then, the slider 106 starts backward movement (in a
direction of arrow D) (step S21). The scraper 311 moves down (step
S22). Since the slider 106 moves in the direction of arrow D while
the scraper 311 is down, the screen 201 is evenly coated with the
ink 51 as illustrated in FIG. 5 (step S23). Finally, the scraper
311 moves up (step S24), and the slider 106 finishes its backward
movement (step S25). These are printing operations on the work
110.
[0109] By repeating above-stated operations for each of works
continuously, printing can be performed on the works
continuously.
[0110] A characteristic feature of embodiment 1 is that the
pressure squeegee 61 is provided as a supplementary squeegee for
the main squeegee 63. Further, the scraper squeegee 65 is provided
as a supplementary squeegee for the main squeegee 63.
[0111] A squeegee of the screen printer must have the following
three functions:
[0112] (1) a pressure function for making the screen 201 in contact
with the work 110;
[0113] (2) a deposition function for depositing the ink 51 to the
work 110 through the screen 201; and
[0114] (3) a scraper function for scraping the excessive ink 51 on
the screen 201.
[0115] According to the related art, the pressure function,
deposition function, and scraper function are achieved by a
squeegee. However, according to embodiment 1, the three functions
are shared by the pressure squeegee 61, main squeegee 63, and
scraper squeegee 65, i.e., the pressure squeegee 61 has the
pressure function, the main squeegee 63 has the deposition
function, and the scraper squeegee 65 has the scraper function.
[0116] FIG. 26 illustrates a front view of the pressure squeegee
61. FIG. 27 illustrates a top view of the pressure squeegee 61 and
main squeegee 63.
[0117] As illustrated in FIGS. 26 and 27, the pressure squeegee 61
and main squeegee 63 have a same width W. It is also possible to
make a width of the pressure squeegee 61 wider than a width of the
main squeegee 63. Accordingly, the pressure squeegee 61 presses an
area on the screen 201 wider than the width of the main squeegee
63. Hence, the screen 201 is able to be pushed down for the full
width of the main squeegee 63.
[0118] The pressure by the pressure squeegee 61 is enough as far as
the screen 201 can be contacted with the work 110. The pressure
squeegee 61 is provided ahead of the main squeegee 63 in the
printing direction. Therefore, a surface of the screen 201 and a
surface of the work are almost parallel between the pressure
squeegee 61 and the main squeegee 63, or the surfaces are contacted
each other between the pressure squeegee 61 and the main squeegee
63. Since the surface of the screen 201 and the surface of the work
110 are contacted, the problem as illustrated in FIG. 22, that
angles between the screen 201 and the work 110 vary in the
positions on the screen, can be solved. Further, a quality of
printing can be improved. An angle .theta.1 between the pressure
squeegee 61 and the work 110 (or screen 201) should be 80-85 degree
(80-85.degree.). The pressure squeegee 61 can be in any material,
e.g., rubber and plastic, as far as the screen 201 is not damaged.
Since the ink 51 is provided between the scraper 311 and the main
squeegee 63, and the screen 201 is evenly coated with the ink by
the scraper 311, the pressure squeegee 61 performs printing by
using the evenly coated ink. This printing by the pressure squeegee
61 is not enough. However, the next coming main squeegee and the
ink carried by the main squeegee can realize printing in high
quality.
[0119] FIG. 28 illustrates a front view of another example of the
pressure squeegee 61.
[0120] FIG. 29 illustrates a top view of the pressure squeegee 61
and the main squeegee 63.
[0121] In FIGS. 28 and 29, the pressure squeegee 61 has a pair of
left and right squeegee parts (a pair of squeegees). In FIGS. 28
and 29, a width V of the left and right squeegee parts is slightly
wider than the width W of the main squeegee 63. Since the screen
201 does not contact with the pressure squeegee 61 at all in an
area of a width U between the squeegee parts of the pressure
squeegee 61, printing is not performed in this area by the pressure
squeegee 61, i.e., printing is performed only by the main squeegee
63. By arranging a printing field (a printing pattern of screen
printing) in the area of the width U, it is possible to print only
by the main squeegee 63 as in the related art.
[0122] A main function of the main squeegee 63 is to deposit the
ink 51 from the screen 201. An angle .theta.2 between the main
squeegee 63 and the work 110 (or screen 201) should be smaller for
depositing the ink 51 smoothly. For example, it should be 10-70
degree. When there is a through-hole or groove on the work 110, and
the through-hole or groove must be filled with the ink 51, the
angel .theta.2 should be smaller. When the screen 201 is thick, the
.theta.2 should be also smaller. By making the angle .theta.2
smaller, an efficiency in deposition of the ink 51 is improved.
However, there is a tendency that an excessive ink 51 remains on
the screen 201 after printing.
[0123] A function of the scraper squeegee 65 is to scrape the
excessive ink 51 on the screen after printing. An angle .theta.3
between the work 110 (or screen 201) and the scraper squeegee 65
should be close to 90 degree for scraping the ink on the screen
201, e.g., 70-90 degree The scraper squeegee 65 can also be in any
material, e.g., rubber, plastic, etc. as far as the screen 201 is
not damaged.
[0124] The scraper squeegee 65 also has a function to make the
surface of the screen and the surface of the work contacted each
other between the main squeegee 63 and the scraper squeegee 65 even
after the main squeegee 63 has passed.
[0125] In embodiment 1, the pressure squeegee 61, main squeegee 63,
and scraper squeegee 65 are arranged in parallel in the printing
direction with determined intervals. Three squeegees which are
arranged in parallel press the screen simultaneously, and screen
printing is performed.
[0126] The screen printer in embodiment 1 differs from the screen
printer using the plurality of squeegees according to the related
art as illustrated in FIGS. 24 and 25. In the screen printer
according to embodiment 1, the plurality of squeegees moves in a
same determined area (i.e., printing field) on the screen for one
stroke.
[0127] In embodiment 1, the pressure squeegee 61 and the scraper
squeegee 65 are provided. However, either the pressure squeegee 61
or the scraper squeegee 65 is not necessary. When the pressure
squeegee 61 is not provided, the main squeegee 63 also has the
pressure function of the pressure squeegee 61. When the scraper
squeegee 65 is not provided, the main squeegee 63 also has the
scraper function of the scraper squeegee 65.
[0128] Embodiment 2.
[0129] In embodiment 2, a pressure roller 70 (an example of a
pressure unit) is used instead of the pressure squeegee 61.
[0130] FIG. 30 illustrates a printing operation in case of using
the pressure roller 70.
[0131] FIG. 31 illustrates an operation of returning the ink in
case of using the pressure roller 70.
[0132] FIG. 32 illustrates a front view in case of using the
pressure roller 70.
[0133] FIG. 33 illustrates a top view in case of using the pressure
roller 70.
[0134] The pressure roller 70 is attached for allowing rotation by
a roller holder 73. The roller holder 73 is attached to the slider
106 for allowing up and down movement. The pressure roller 70 is
made of rubber, urethane, plastic, etc. The pressure roller 70 can
be in any material, as far as the screen 201 is not damaged. A
function of the pressure roller 70 is completely same as the stated
function of the pressure squeegee 61, and the pressure roller 70
has a function for pressing the screen 201. Since the pressure
roller 70 is attached for allowing rotation, a friction against the
screen 201 is seldom generated.
[0135] FIG. 34 illustrates a front view in case of dividing the
pressure roller 70 into a right pressure roller 71 and a left
pressure roller 72.
[0136] FIG. 35 illustrates its top view.
[0137] In FIGS. 34 and 35, an idea shown in FIGS. 28 and 29 is
applied to a roller. In FIGS. 34 and 35, the width V is wider than
the width W, and the width U is wider than the printing field. By
making the width U wider than the printing field, the right
pressure roller 71 and the left pressure roller 72 become not to
take part in the printing operation at all and achieve only the
pressure function.
[0138] In FIGS. 36 and 37, the right pressure roller 71 and the
left pressure roller 72 are shaped differently.
[0139] The right pressure roller 71 and the left pressure roller 72
are in a form of a sliced cone. Since the cone is sliced, a taper
part is generated. Hence, a possibility of damaging the screen 201
is lessened. An angle of the taper part should be almost same as an
angle of the screen bent by the pressure.
[0140] FIG. 38 illustrates other examples of the pressure roller
70, the right pressure roller 71, and the left pressure roller
72.
[0141] In (a) of FIG. 38, both ends of the pressure roller 70 are
rounded.
[0142] In (b), (c), and (d) of FIG. 38, the right pressure roller
71 and the left pressure roller 72 are rounded. In each of (a),
(b), (c), and (d) of FIG. 38, the screen 201 is pressed by a
rounded surface. Therefore, the screen 201 is not damaged.
[0143] In FIG. 39, the right pressure roller 71 and the left
pressure roller 72 can slide in directions of arrows, i.e., a
direction of a rotary axis.
[0144] Since a width between the right pressure roller 71 and the
left pressure roller 72 can be changed, an optimal pressure width
can be selected based on a size of the printing field or a width of
the squeegee. Hence, a better pressure function can be realized,
and a damage on the screen 201 can be lessened by preventing an
excessive pressure. For example, when even if the screen 201 is
small, the width between the right pressure roller 71 and the left
pressure roller 72 is wide, very strong force is given at both ends
of the screen 201. Therefore, a slack of the screen 201 or a damage
on the screen 201 can be caused. In that case, the right pressure
roller 71 and the left pressure roller 72 should be slid from (a)
of FIG. 39 to (b) in FIG. 39 to narrow the width between the right
pressure roller 71 and the left pressure roller 72.
[0145] Embodiment 3.
[0146] In FIG. 7, the pressure squeegee 61 and the scraper 311 are
unified (attached together or combined). The main squeegee 63 and
the scraper squeegee 65 are also unified.
[0147] The scraper 311 is attached for allowing rotary movement by
a rotary unit 67 in a direction of arrow U or arrow V. The rotary
unit 67 is attached to the slider 106 for allowing up and down
movement. As illustrated in (a) of FIG. 7, the rotary unit 67
rotates in the direction of arrow V during printing. The angle
.theta.1 between the work 110 and the pressure squeegee 61 is set
at 85 degree, for example. As illustrated in (b) of FIG. 7, when
the ink is returned by the scraper 311, the rotary unit 67 rotates
in the direction of arrow U, and an angle .theta.6 is set at 90
degree approximately.
[0148] As stated, by unifying the pressure squeegee 61 and the
scraper 311, a distance between the pressure squeegee 61 and the
main squeegee 63 can be narrowed. Hence, a size of an apparatus can
be reduced.
[0149] In case that the main squeegee 63 and the scraper squeegee
65 are unified, an angle between the squeegee and the work (or
screen) should be .theta.2<.theta.3 as described in Embodiment
1.
[0150] Since the main squeegee 63 and the scraper squeegee 65 are
unified, a distance between the main squeegee 63 and the scraper
squeegee 65 can be narrowed. Hence, a size of the apparatus can be
reduced. Further, a number of parts can be reduced.
[0151] In FIG. 8, the pressure squeegee 61 and the scraper 311 are
unified.
[0152] The scraper 311 is attached to the slider 106 for allowing
up and down movement. The pressure squeegee 61 is attached to the
scraper 311 for allowing up and down movement by an air cylinder
69. As illustrated in (a) of FIG. 8, during printing, the pressure
squeegee 61 moves down while the scraper 311 is up, and the angle
.theta.1 between the work 110 and the pressure squeegee 61 is set
at 85 degree, for example. As illustrated in (b) of FIG. 8, in case
that the scraper 311 returns the ink, the pressure squeegee 61 is
lifted up, and the scraper 311 moves down. The angle .theta.6 is
set at 90 degree approximately.
[0153] As stated, since the pressure squeegee 61 is attached to the
scraper 311 for allowing movement, a size of the slider 106 can be
reduced. Hence, a size of the apparatus can be reduced.
[0154] It is possible to use a spring, motor, screw, etc. instead
of the air cylinder 69 for attaching the pressure squeegee 61 for
allowing up and down movement. It is also possible to allow rotary
movement of the scraper 311 as in FIG. 7.
[0155] As illustrated in FIG. 40, the pressure roller 70 (right
pressure roller 71 and left pressure roller 72) can be unified with
the scraper 311.
[0156] Embodiment 4.
[0157] In FIGS. 9, 10 and 11, a plurality of squeegees moves up and
down together.
[0158] In FIG. 9, the main squeegee 63 and the scraper squeegee 65
move up and down together. In FIG. 10, the pressure squeegee 61 and
the main squeegee 63 move up and down together. In FIG. 11, the
pressure squeegee 61, the main squeegee 63 and the scraper squeegee
65 move up and down together.
[0159] In each case, the apparatus can be made simply.
[0160] It is also possible to make the pressure roller 70 (right
pressure roller 71 and left pressure roller 72) move together with
some other squeegee as illustrated in FIGS. 41 and 42.
[0161] It is not necessary that the pressure squeegee 61 and the
scraper squeegee 65 are called as the squeegees. They can be
replaced by other things with a pressure function or a scraper
function.
[0162] It is not necessary that the pressure unit is the roller. It
can be replaced by a squeegee or a slider which simply slides on
the surface of the screen 201 in pressing. The pressure unit can be
replaced by anything as far as it presses the screen 201.
[0163] Embodiment 5.
[0164] FIG. 43 illustrates the screen printer using two
squeegees.
[0165] An apparatus in FIG. 43 differs from the apparatus in FIGS.
24 and 25. In FIG. 43, the squeegees 111 and 112 are used together
successively to print one area on a screen for one stroke. In case
of FIG. 24, only one squeegee is used for one stroke. In case of
FIG. 25, each of squeegees prints different area. In FIG. 43, the
squeegees 111 and 112 are attached for allowing rotary movement in
the directions of arrow U or arrow V by the rotary units 67 as
illustrated in FIG. 7. The rotary units 67 are attached to the
slider 106 for allowing up and down movement. When printing is
performed in the direction of arrow A in (a) of FIG. 43, the
squeegee 112 is the pressure squeegee 61 and the squeegee 111 is
the main squeegee for printing. When printing in the direction of
arrow A is finished, the rotary units 67 rotate in the direction of
V as illustrated in (b) of FIG. 43. When printing is performed in
the direction of arrow D as in (c) of FIG. 43, the squeegee 111 is
the pressure squeegee, and the squeegee 112 is the main squeegee.
An angle of the rotary movement should be 10-20 degree, i.e., an
angle .theta.7 should be 80-95 degree. The angle .theta.7 of the
pressure squeegee is set at 80-95 degree for preventing the
pressure squeegee from performing printing as much as possible. The
angle of the pressure squeegee should be close to 90 degree, if
possible, for preventing the printing by the pressure squeegee.
[0166] Embodiment 6.
[0167] The scraper 311 and the pressure 61 in the stated
arrangement can be replaced each other.
[0168] In FIG. 44, the scraper 311 and the pressure squeegee 61 in
FIG. 2 are replaced each other. In FIG. 45, the scraper 311 and the
pressure squeegee 61 in FIG. 5 are replaced each other. It is also
possible that the pressure squeegee 61 and the main squeegee 63 are
moved unitedly as illustrated in FIGS. 46 and 47. It is also
possible to allow up and down movement of the pressure squeegee 61
independently from the main squeegee 63 by the air cylinder 69 as
illustrated in FIG. 48.
[0169] FIG. 49 illustrates a top view in case that the pressure
squeegee is divided into left and right.
[0170] The pressure squeegee 61 has an angle .theta.9 against the
printing direction. By making the angle .theta.9 smaller than 90
degree, the ink 51 is gathered in a center of the main squeegee 63
as shown in arrows. In this way, leakage of the ink 51 from both
sides of the main squeegee 63 is prevented, and shortage and lack
of the ink 51 can be prevented.
[0171] Even though an illustration is not provided, the scraper 311
and the pressure roller 70 (right pressure roller 71 and left
pressure roller 72) in the stated arrangement can be replaced each
other.
[0172] Embodiment 7
[0173] Explanations are made on a pre-contact printing method with
a low pressure by using a solder paste (the ink is also called as
the paste.).
[0174] Since the solder paste contains solder particles with a
larger diameter than other types of paste for screen printing, a
mask (metal mask) (the screen is also called as the mask.) without
mesh is normally used for printing by using the solder paste.
Therefore, in printing by using the solder paste, it is difficult
to use a basic method for screen printing, i.e., "off-contact
printing method." In the "off-contact printing method", a constant
clearance is maintained between the mask and the work, and a line
contact is created by the squeegee for the mask and the work.
[0175] FIG. 50 illustrates a leakage of the paste in the
"off-contact printing method."
[0176] As illustrated in FIG. 50, the paste 51 (the ink is also
called as the paste.) is flowed by a squeegee 511, and pushed
toward a lower forward direction, i.e., a direction vertical to a
surface of the squeegee. However, since a mask 501 is without mesh,
the paste tends to be leaked from the opening 32 of the mask. The
paste 51 is also pressed and flowed at a place which is a few
millmeter ahead of the contacting line of the screen 201 and the
work 110, and leaked from the opening 32 of the mask. Since there
is a certain space between the screen 201 and the work 110, the
paste 51 tends to be spread largely. Therefore, the "off-contact
printing method" is not used in a surface mount technology
(SMT).
[0177] In the SMT, an "on-contact printing method" is mainly used
in the printing by using the solder paste. FIG. 51 illustrates
squeezing and detaching of the mask in the "on-contact printing
method." As illustrated in FIG. 51, a surface contact of the metal
mask 501 and the work 110 is created and squeezed. Then, the
opening is filled with the paste 51. After a constant time is
passed, the metal mask 501 and the work 110 are detached
mechanically (detached from the mask). In this method, the paste is
not leaked during squeezing.
[0178] In the "on-contact printing method", even if the opening of
the mask is with a various diameter, the opening can be filled with
the paste evenly. Hence, the "on-contact printing method" is
recommended by many manufacturers of solder paste printers and
adopted by most of the solder paste printer users.
[0179] However, since the metal mask 501 and the work 110 are
contacted each other for a long time, the paste often spreads due
to capillarity. Further, since the mask is detached, when the paste
becomes less flowing, the paste 51 tends to be remained in the
opening of the mask. Especially in a fine pitch printing, the
evenness tends to drop. Further, when a large area is printed,
since the paste is sticky, a condition of detaching of the mask at
a center of the metal mask and a condition of detaching of the mask
at a point close to a circumference of the metal mask differ.
Hence, it is very difficult to print evenly. Further, a metal
squeegee 512 damages the metal mask 501.
[0180] Explanations are made on a pre-contact printing method with
a low pressure.
[0181] In Embodiment 7, the "pre-contact printing method" with a
low pressure by using a rubber squeeze is used to solve the
above-stated problems in printing by using the solder paste.
[0182] FIGS. 52 and 53 illustrate a configuration of a pre-contact
squeegee.
[0183] As illustrated in FIGS. 52 and 53, in the "pre-contact
printing method", the pre-contact squeegee 61 (supplementary
squeegee) (the pressure squeegee is also called as the pre-contact
squeegee.) is provided ahead of the printing squeegee 63 (main
squeegee) for making the screen and the work contacted each other.
In the "pre-contact printing method", a band contact of the mask
and the work is created between the pre-contact squeegee 61 and the
printing squeegee 63 to solve the problems in the "off-contact
printing method." In this method, it is possible to realize both a
good filling condition achieved in the "on-contact printing method"
and a continuous detaching of the mask achieved in the "off-contact
printing method."
[0184] Besides, in case that the rubber squeegee is used, when the
rubber squeegee moves on the opening of the metal mask, the rubber
squeegee tends to slip in the opening of the metal mask, and
scrapes the paste which is already filled in the opening.
Therefore, the opening of the metal mask is not filled with the
paste sufficiently. The problem of the insufficient filing of the
paste in the opening of the metal mask is not caused because the
rubber squeegee is used. The problem occurs as an excessive
pressure is given to the squeegee. Therefore, the problem can be
solved by setting a pressure at a low level and using a rubber
squeegee which is polished slantingly.
[0185] In the "pre-contact printing method", the paste can be put
out of the opening of the mask smoothly without a remaining, and
the spread can be reduced. Therefore, it is possible to print
continuously without cleaning or washing the mask, that is
necessary in regular on-contact screen printing.
[0186] FIG. 54 illustrates a condition of the screen and the work
when the pre-contact squeegee is placed downward.
[0187] The pre-contact squeegee 61 and the screen 201 are contacted
each other outside a printing area. However, as illustrated in FIG.
54, the pre-contact squeegee 61 and the screen 201 are not
contacted in the printing area. In the whole printing area, a small
space S1 is maintained between the work 110 and the screen 201,
that is the work 110 and the screen 201 are not contacted due to a
tension of the screen. Because of the small space S1, the paste is
not put on a back side of the mask, and the paste is not
leaked.
[0188] It is also possible to move down the pre-contact squeegee 61
and stop at a point in a middle to maintain a space S2 between the
work 110 and the screen 201. By doing so, the work 110 and the
screen 201 are not contacted in the whole printing area. The space
S2 is not necessary, and the space S1 is maintained anyway even if
the space S2 is not maintained.
[0189] Embodiment 8.
[0190] A phosphor printing by using a two-blade squeegee is
explained.
[0191] In screen printing, the squeegee has the following three
functions:
[0192] 1) contacting the screen with a substrate;
[0193] 2) depositing the paste from the opening of the screen;
and
[0194] 3) scraping an excessive paste on the screen.
[0195] FIG. 55 illustrates a deposition mechanism of the paste.
[0196] In the related art, a pressure (SP), an attack angle (SA),
and a squeegee speed (SV) are balanced by using a single squeegee
to set a condition of printing.
[0197] As illustrated in FIG. 55, a force for depositing the paste
51 from the opening of the screen (deposition force) is generated
only when the squeegee moves. A force in a direction vertical to a
surface of the squeegee is given to the paste 51, and the force is
sent forward.
[0198] FIG. 56 illustrates the deposition force of the paste and
the condition of printing.
[0199] As illustrated in FIG. 56, when the attack angle SA
decreases, the deposition force increases. When the squeegee speed
SV decreases, the force is given to the paste for a longer time,
and the "deposition force" increases.
[0200] A phosphor printing method in a plasma display panel (PDP)
and its problems are stated.
[0201] As illustrated in FIG. 57, in the phosphor printing, the
paste must be dropped in a gutter 506 including electrode 507
between barrier ribs 505 with a height of 130 .mu.m or more.
Therefore, it is necessary to set the "deposition force" at a high
level.
[0202] Specifically, the attack angle is often set at
15-20.degree., and the squeegee speed is often set at 30-60 mm/sec.
This condition is modified based on types of the paste and the
screen, and a filling amount of the phosphor is controlled. When
the amount of the phosphor is insufficient, a brightness drops, and
an uneven display is caused. When a deposition force is too much,
an overflow of the paste is caused. Further, the phosphor sticks to
a top of the barrier ribs 505, and colors are mixed beyond the
barrier rib. Therefore, the back side of the screen 201 must be
often cleaned. The overflow of the phosphor during printing must be
prevented to reduce a frequency of cleaning of the back side of the
screen 201.
[0203] FIG. 58 illustrates a relationship of the screen and the
barrier ribs during the phosphor printing.
[0204] FIG. 58 illustrates a relationship of the squeegee 111, the
screen 201, and the substrate 110 (the work is also called as the
substrate) at a C1-C1 section in FIG. 57.
[0205] FIG. 59 illustrates a relationship of the screen, squeegee,
and barrier ribs during the phosphor printing and the leakage of
the paste.
[0206] FIG. 59 illustrates a side view of the phosphor printing at
a C2-C2 section in FIG. 57. Since the attack angle of the squeegee
is small, the "deposition force" is high, and the paste flows in a
lower forward direction. Since a printing surface of the squeegee
is with a length of 10 mm approximately as shown in FIG. 59, a
gutter is filled with the paste a few millimeters ahead of a
contacting point. Since a small clearance C is maintained between
the screen and the substrate in an area which is a few millimeters
ahead in a direction of movement of the squeegee, there is a
possibility that the paste 51 is leaked in the small clearance C.
The back side of the screen is cleaned to get rid of the leaked
paste. Therefore, if the overflow is prevented, the frequency of
cleaning of the back side can be reduced.
[0207] FIG. 60 illustrates a configuration of a two-blade squeegee
in Embodiment 8. An angle of the supplementary squeegee 61 (the
pre-contact squeegee is also called as the supplementary
squeegee.), which is provided ahead, is 70-85.degree.. The
supplementary squeegee is used to make the screen 201 and the
substrate 110 contacted each other.
[0208] FIG. 61 illustrates a preventing method of the overflow of
the paste by using the two-blade squeegee.
[0209] FIG. 61 illustrates an actual phosphor printing.
[0210] In this case, when the attack angle of the supplementary
squeegee 61 is 70-85.degree., the paste 51 goes through the screen
201 and just appears on the back side of the screen 201. Therefore,
the paste 51 does not affect printing by the main squeegee 63.
[0211] The screen is contacted with the barrier ribs by the
supplementary squeegee 61 which is ahead. The gutter is covered by
the screen in advance, and filled with the phosphor by the main
squeegee 63. Therefore, the overflow is prevented.
[0212] In this method, because there is no possibility of overflow,
a paste with relatively low sticking level and higher liquidity can
be used. Therefore, it is possible to set a higher squeegee speed.
Hence, the throughput can be improved.
[0213] The overflow can be prevented by using the two-blade
squeegee. Further, since the printing process becomes steady, a
various paste can be used. Hence, the quality of coating and the
productivity can be improved.
[0214] As stated, according to this invention, the screen printer
for printing evenly can be realized.
[0215] According to the preferred embodiment of this invention,
three functions of the squeegee are shared by the plurality of
squeegees. Hence, the squeegees effectively formed for achieving
each of the functions can be used. Further, printing such as
filling out of the through-hole, groove, etc. can be performed
efficiently.
[0216] Further, since the plurality of squeegees can be controlled
individually, the pressure of each of the squeegees can be changed.
It is also possible to determine a position for moving up or down
for each of the squeegees.
[0217] According to the preferred embodiment of this invention,
since a plate detaching apparatus is not used, an unnecessary
pressure is applied to the screen. Hence, problems such as shifting
of a printing position and reduction in durability of the screen
plate do not occur.
[0218] According to the preferred embodiment of this invention,
even if the pressure unit is used instead of the pressure squeegee,
same effects can be realized.
[0219] According to this invention, since the pressure squeegee or
pressure unit is arranged in left and right, the pressure squeegee
or pressure unit does not print before printing by the main
squeegee. Hence, the main squeegee can perform printing.
[0220] Having thus described several particular embodiments of the
invention, various alterations, modifications, and improvements
will readily occur to those skilled in the art. Such alterations,
modifications, and improvements are intended to be part of this
disclosure, and are intended to be within the spirit and scope of
the invention. Accordingly, the foregoing description is by way of
example only and is limited only as defined in the following claims
and the equivalents thereto.
* * * * *