JPS62279946A - Improved screen printer - Google Patents

Abstract

PURPOSE:To prevent the variation of the relative size of a character or a graph and the occurrence of uneven concentration of ink, by providing a holder for moving the end section of a screen on the snap-off angle side such that the snap-off angle between the screen and a member to be printed is constant or approximately constant. CONSTITUTION:There exists a holder 11 for moving an end section A such that an angle alpha is constant as a tip P of a squeegee moves, so as to make the lengths of the cross-sections A, B of a screen constant (L), and it can be seen that said cross-section is a hyperbola which is satisfied by conversion of coordinates. Needless to say, the obtained mathematical locus is a theoretical one and an actual profile of a holder may sometimes shift slightly from said locus in the engineering practice. The simplest approximation is to move on a line in the direction of an asymptote for said hyperbola.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Object of the Invention) The present invention relates to improvements in foreign exchange in screen printing.

Screen printing is performed using a screen (
The four circumferences of the 1-mesh-shaped fabric were fixed under tension to the plate frame, and a resist was created manually or photochemically on top of the plate, resulting in a shallow ark-like shape. Printing is carried out by putting ink for screen printing on the plate, pressing and rubbing the plate surface with a squeegee, and pushing the ink from the part without the plate through the screen surface onto the surface of the printing material placed on the underside of the plate. It is something to do.

Screen printing allows the use of many types of ink and has a thick young layer of ink, so it has excellent weather resistance and chemical resistance, and for this reason, it has recently been used for printing printed circuit boards such as IC circuits.

By the way, as shown in Fig. 2, as long as the length of the screen in the squeegee movement direction is constant, the tA mark at the point P that contacts the tip of the squeegee without applying any tension to the screen is originally an ellipse. It should be. However, since the surface of the printing material is flat, the squeegee applies a certain tension to the screen and forces the ink through the screen surface onto the printing material, but the squeegee does not reach the edge of the printing material. Accordingly, the squeegee is required to apply greater tension, so the 14 meshes of the screen become larger on the edge side, which causes uneven ink density.

Also, as the squeegee moves to the end, the snap-off angle α between the screen and the printing material changes on the side opposite to the side where the squeegee holds ink, so that after the squeegee passes, Surface tension changes both the time that the ink protruding downward from the mesh of the screen contacts the printing medium and the amount of ink that contacts it.
Such a change in angle also caused unevenness in the ink density on the printing medium.

Therefore, in Fig. 2, the tension on the screen is constant regardless of the movement of the squeegee, and the angle α between the screen and the printing material is It is necessary to always be constant.

It is an object of the present invention to provide a screen printing machine configuration in which such angle α can be kept constant and the tension of the screen can also be kept constant.

(Structure of the Invention) As the squeegee moves, the ink is distributed at the tip of the squeegee on the side opposite to length measurement that holds the ink so that the angle between the screen and the printing material is kept constant. Providing a frame in which the edge of the screen on the holding side moves, that is, as shown in Figure 3, the edge A of the screen moves so that the angle α is constant at the tip P of the squeegee. The present invention is realized by providing the frame 11 that

Therefore, in the screen of the present invention, as described above, since a part of the edge of the screen is moved, the two frames along the moving direction of the squeegee are not necessary among the frames for fixing the screen.

We will analyze the shape of the cross section of such a frame. − In the graph of Figure 4, the angle α between the screen and the printing substrate
The edge A(x, y) of the screen so that
Find the trajectory of the movement.

If the coordinate axis of the edge B of the screen is (0, S), then x=L1 CO5(X+L2 Cosβ5inct
=Y/LL, Sinβ=S/L! Ll +L2
=S holds true.

From the above, (S sin α) 2 + (x 5ina-y
coSα) z= (L sinα−y)2 Transforming this, Sl +xZ −2xy gotα+2Ly
caSeca= L2 +y 2 ... (1) Here, the coordinates obtained by rotating the coordinates of (x, y) by 0 are (
x', y'), then x=x'cosO-y' s:n0y=y
'cosO+x' 5inOwhere, Xo・y'
In order to eliminate the term, we specifically set 20-α=π/2, and if we express the above equation (11) as (x', y'), after complicated calculations we get (x' - L sin (α/ 2+π/4)
) 2-(Y'+LcoS(α/2+π/4) ) 2
=32 · sin α is obtained.

In other words, the locus of frame 11 has (x, y) coordinates α/2+π
At the coordinates rotated by /4 in the positive direction, M (L, si
n (α/2+π/4)-L CO5((X/ 2 +
π/4) Set the asymptote at 45 degrees with l as the center, and set the focus at (L 5in(α/2+π/4) ± s+na*
.

-L cos (α/2+π/4) ).

That is, as the tip P of the squeegee moves, the angle α is kept constant, and the lengths of the cross sections A and H of the screen are kept constant (L).
There is a frame 11 for moving the end part A as shown in FIG.
It turns out that this cross-sectional shape is a hyperbola satisfied by the above coordinate change.

Heat theory, the mathematical trajectory obtained by the above formula is theoretical, and it is possible in engineering that the actual shape of the frame may be slightly different from such a trajectory, but the present invention
Of course, the case of an approximate 4A trace with such a deviation is also included.

That is, "the angle is constant" in the present invention means "the angle is constant or almost constant." In addition, in order to move the edge of the screen 3 along the frame 11 in the above configuration, (i)
A method of moving the squeegee manually according to the movement of the squeegee: (11) A belt is placed along the frame 11.12, the edge of the screen 3 is fixed to this, and the belt is moved with the movement of the squeegee using a step motor or the like. Although it is possible to consider a method of moving while recirculating the rotation, the present invention does not limit the specific configuration in this respect at all.

(Effects of the Invention) By using the frame of the present invention, the angle between the screen and the printing material on the opposite side of the side that holds ink at the tip of the squeegee between the screen and the printing material is always constant, and , even if the squeegee moves, the length of the screen in the squeegee movement direction will be longer (A PIE in Figures 3 (a) and (b))
is always set constant from the beginning, so the tension of the screen against the squeegee remains unchanged.

Therefore, as the squeegee moves, the ink passes through the screen at a constant rate, eliminating any unevenness in the density of the ink on the printing material, making it possible to print uniformly.

[Brief explanation of drawings]

Figure 0'51 A sketch showing the outline of screen printing Figure 2: A cross-sectional view to explain the principle of undeveloped J (The dotted line indicates the locus of the ellipse when the length of the screen is constant.) Figure 3: Side view fjS4 diagram showing the configuration of the varnish mite screen 11.12 - Frame 2 of undeveloped IJJ - Squeegee 3 - Screen 4 - Printing material

Claims (1)

[Claims] As the squeegee moves, the edge of the screen that holds the ink changes so that the angle between the screen and the printing material remains constant on the opposite side of the tip of the squeegee from the side that holds the ink. Improved screen printing machine characterized by a moving frame