JPH08197714A - Screen printer - Google Patents

Abstract

PURPOSE: To provide a screen printer by which printing can be performed with good accuracy and without damaging a screen even when a face to be printed is a curved face, an inclined face or an irregular face. CONSTITUTION: A screen 6 arranged horizontally on a material GLB to be printed wherein the printing face held on a sucking stage 5 is an arc face and has specified microholes, a squeezee 8 moving on a screen 6 in the arrow mark direction and scraping ink 9 placed on the screen 6 and a mechanism 10 consisting of cams 1a and 1b and up and down sliding shaft 2 for moving up and down the sucking stage 5 synchroneously with the movement of the squeezee 8 so as to keep constant the distance (g) between the article GLB to be printed just below the squeezee 8 and the screen 6 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing machine, and more particularly to a screen printing machine capable of printing on curved surfaces, slopes and irregular surfaces without damaging the screen (plate).

[0002]

2. Description of the Related Art In screen printing, a rubber spatula called a squeegee is used to scratch the ink placed on the screen, and the ink is transferred to a printing object placed below the screen through microscopic holes formed in the screen. Done by

Below, as a printing material for screen printing,
The light guide of the backlight of the liquid crystal display device will be described as an example, but the present invention is not limited to this. That is, a dot pattern for light diffusion for emitting light from the light guide body is printed on the bottom surface of the light guide body which is built in the liquid crystal display module and constitutes a backlight together with a fluorescent tube as a light source.

In the liquid crystal display module, for example, two transparent insulating substrates made of glass or the like are superposed on each other with a predetermined gap so that the surfaces on which the transparent pixel electrodes for display and the alignment films are laminated face each other. A frame-shaped sealing material is provided on the edge between the two substrates, and both substrates are bonded together, and liquid crystal is sealed inside the sealing material between both substrates from the liquid crystal sealing port provided in part of the sealing material. Further, a liquid crystal display panel (that is, a liquid crystal display unit, a liquid crystal display element, and LCD: also referred to as a liquid crystal display) in which a polarizing plate is provided outside each of the substrates, and a liquid crystal display panel disposed below the liquid crystal display panel. A backlight composed of a fluorescent tube for supplying light to the panel and a light guide, a drive circuit board for the liquid crystal display panel arranged outside the outer peripheral portion of the liquid crystal display panel, and these respective members are stored. A frame-shaped body is a molded article which, accommodating each of these members, is configured to include a liquid crystal display window is opened metal frame or the like.

The structure of the backlight will be described in more detail. The light emitted from the light source is guided to a direction away from the light source.
A light guide which is a rectangular parallelepiped made of a synthetic resin plate such as a transparent acrylic resin for evenly irradiating light on the entire liquid crystal display panel, and along the side surface near the side surface (that is, the light incident end surface) of the light guide body. A fluorescent tube which is a light source arranged in parallel with the side surface,
A lamp reflection sheet that covers the fluorescent tube over substantially its entire length, has a U-shaped cross section, and returns the light of the fluorescent tube to the light guide so as not to leak to the outside, and is arranged on the light guide.
It is composed of a diffusion sheet that diffuses light from the light guide body, and a reflection sheet that is disposed under the light guide body and reflects the light from the light guide body toward the liquid crystal display panel.

The light entering the light guide from the fluorescent tube is guided while being totally reflected in the light guide due to the difference in refractive index between the air and the light guide, but due to diffuse reflection, the upper surface of the light guide. In order to emit light from the light guide body, a large number of, for example, white circular light diffusion dot patterns (see reference numeral DP in FIG. 4) having a higher refractive index than the light guide body are arranged and printed on the bottom surface of the light guide body. There is. Such a backlight is described, for example, on page 217 of Nikkei BP's flat panel display 1994.

[0007]

Conventionally, the light guide body of the backlight has been a flat plate (a rectangular parallelepiped), but recently, in order to reduce the weight and thickness of the liquid crystal display module, the cross section of the bottom surface of the light guide body is used. Light guides having an arc shape and wedge-shaped (that is, trapezoidal cross-section) light guides have been used. Note that the light guide member having such a shape is manufactured by molding, unlike the flat light guide member.

However, if a light diffusion dot pattern is to be screen-printed on the bottom surface of a light guide having such a curved surface or a sloped surface, the bottom surface, which is the surface to be printed, is a curved surface or a sloped surface. I couldn't. Even if printing is possible, since the printing surface is a curved surface or a slope, ink may flow during printing, and it is difficult to keep the distance (spacing, gap) between the screen and the printing object constant, so printing accuracy is poor. There was a problem that it became scratched or damaged the screen.

An object of the present invention is to provide a screen printing machine capable of performing printing accurately even when the surface to be printed is a curved surface or an inclined surface without damaging the screen.

[0010]

In order to solve the above-mentioned problems, a screen printing machine of the present invention comprises a base for holding an object to be printed, a screen provided on the base and having predetermined fine holes, and It is characterized by comprising a squeegee for moving ink on the screen in contact with the screen from one end to the other end of the screen, and a mechanism for moving the stand up and down.

Further, the screen printing machine of the present invention includes a base for holding the printing object, a screen which is provided substantially horizontally on the printing object held on the table and has predetermined micropores, The screen is brought into contact with the screen and moved from one end to the other end of the screen, the ink placed on the screen is covered, and the distance between the screen directly below the squeegee and the screen is constant. So as to keep the squeegee moving, the mechanism for moving the table up and down in synchronism with the movement of the squeegee.

Further, the mechanism for moving the table up and down has at least two upper and lower slide shafts whose upper ends are fixed to or in contact with both ends of the table, respectively, and contact with respective lower ends of the shafts. It is characterized by including at least two cams having a predetermined shape and arranged.

Further, the mechanism for moving the table up and down is configured to include at least two stepping motors having screw parts whose upper ends are fixed to or in contact with both ends of the table, respectively. Characterize.

Further, the mechanism for moving the table up and down is configured to include at least two air cylinders having vertical slide shafts whose upper ends are fixed to or in contact with both ends of the table, respectively. Is characterized by.

Further, the table is characterized in that it has means for adsorbing the material to be printed on the table.

[0016]

In the screen printing machine of the present invention, in synchronization with the movement of the squeegee, the table holding the material to be printed is moved up and down,
As the distance between the screen directly below the squeegee and the screen is kept constant from the start to the end of printing, even if the print surface is a curved surface, slope, or irregular surface, it is the same as when it is a flat surface. Printing can be performed accurately and without damaging the screen.

[0017]

【Example】

Embodiment 1 FIGS. 1A to 1C are diagrams showing a configuration of a screen printing machine according to a first embodiment of the present invention and an operation of the screen printing machine from the start to the end of printing.

In FIG. 1, GLB is a light guide, which is an object to be printed (printing object) for printing a light diffusion dot pattern (see reference numeral DP in FIG. 4) on the bottom surface thereof, and 5 is a light guide GLB.
, A suction table for holding the same by known suction means (not shown),
Is a screen (printing plate) that is horizontally installed on the light guide GLB that is adsorbed and fixed on the adsorption table 5, and is provided with predetermined micro holes corresponding to the dot pattern to be printed. Screen frames provided on both left and right ends, 9
Is ink on the screen 6, and 8 is moved on the screen 6 from one end on the left side of the screen 6 to the other end on the right side as shown by an arrow while being in contact with the screen 6, and is placed on the screen 6. The ink 9 covers the squeegee 10 and the light guide GLB and the screen 6 directly below the moving squeegee 8.
A mechanism for vertically moving the suction table 5 in synchronism with the movement of the squeegee 8 so as to keep the distance g between and is constant, 2 is a vertical slide shaft, and 1a and 1b are cams. In the present embodiment, the mechanism 10 for moving the suction table 5 up and down has two upper and lower parts whose upper ends are fixed to the central portions of the bottom surfaces of the left and right end portions of the suction table 5 (in the direction perpendicular to the paper surface of the drawing). It is composed of a slide shaft 2 and two cams 1a and 1b having a predetermined shape which are arranged in contact with the lower ends of the upper and lower slide shafts 2, respectively. The predetermined shape is a shape that keeps the distance g between the light guide GLB directly below the squeegee 8 and the screen 6 constant when the suction table 5 is moved up and down in synchronization with the movement of the squeegee 8 by the mechanism 10. And corresponds to the shape and size of the light guide body GLB that is the printing target. The vertical slide shaft 2 which vertically moves up and down by the rotation of the cams 1a and 1b is, of course, supported by the base of the screen printing machine, but the supporting structure thereof is not shown. Further, the lower ends of the vertical slide shaft 2 and the cams 1a and 1b are, of course, not fixed but only in contact with each other.

FIG. 2 (a) is a partial front view showing an example of the details of the portion A (upper end of the vertical slide shaft 2 and the portion fixed to the suction table 5) of FIG. 1 (a), FIG. 2 (b). Is the arrow B in FIG.
It is a partial side view seen from the direction. FIG. 2C is a view similar to FIG. 2A showing another configuration example of the A section.

In FIG. 2, 12 is a rotating shaft, 11 is a bearing, and 13 is a fixing pin for fixing the rotating shaft 12 and the vertical slide shaft 2.

As shown in FIGS. 2 (a) and 2 (b), the upper end of the vertical slide shaft 2 is attracted to the central portion (in the direction perpendicular to the paper surface) of the lower surface of the left and right end portions of the adsorption base 5. The base 5 is fixed so that it can move up and down (the support structure for the vertical slide shaft 2 is not shown). Note that, as shown in FIG. 2C, it may be provided at the center of the left and right side surfaces of the suction table 5.

FIG. 4 is a perspective view of the light guide GLB, the fluorescent tube LP, and the liquid crystal display panel PNL showing the light diffusion dot pattern DP printable by the screen printing machine according to the present invention.

In the example shown in FIG. 4, the light diffusion dot pattern DP has a round dot shape, and the dot diameter of the pattern DP is gradually increased with increasing distance from the fluorescent tube LP, which is a light source, so that the diffuse reflection characteristic is obtained. The light guide G is increased by correcting the decrease in the light amount caused by moving away from the light source.
The surface brightness of the LB is made uniform. The pitch of the dot patterns DP is the same in this example.

The operation of the screen printing machine according to this embodiment will be described below with reference to FIGS.

(A) shows a state before printing (at the start of printing). A light guide body GLB, which is made of acrylic or the like to be printed and has a curved surface (cylindrical surface) and a circular sectional shape, is vacuum-adsorbed on the suction table 5. A predetermined distance g is provided between the light guide GLB directly below the squeegee 8 and the screen 6 by the suction table 5 connected to the cams 1a and 1b at the origin position of the rotation angle of 0 ° via the vertical slide shaft 2. Is maintained.

(B) shows a state during printing. Squeegee 8 is right in the middle. The suction table 5 is tilted by rotating the cams 1a and 1b in the directions of the arrows of 90 °. Again, the light guide GL directly below the squeegee 8
The distance g between B and the screen 6 is kept the same as before printing.

(C) shows the state at the end of printing. Although the suction table 5 is further pushed up by the cams 1a and 1b, the distance g between the light guide GLB immediately below the squeegee 8 and the screen 6 is kept the same.

As described above, the cams 1a and 1b and the vertical slide shaft 2 which rotate in synchronization with the movement of the squeegee 8 in the direction of the arrow.
Thus, the suction table 5 is moved up and down, and the distance g between the light guide GLB immediately below the squeegee 8 and the screen 6 is always kept constant from the start to the end of printing. Therefore, even when the printing surface is a curved surface, an inclined surface, or an irregular surface, printing can be performed with high accuracy and without damaging the screen, as in the case of a flat surface, and the life of the screen can be extended. Further, the design of the dot pattern for light diffusion may be the same as in the case of the conventional flat light guide, and the design cost can be reduced. Further, even if the diameter of the arc of the curved surface of the light guide GLB is changed, it can be easily dealt with by replacing the cams 1a and 1b with those having a shape suitable for it. Note that there is a known technique of forming a dot pattern composed of a convex portion and a concave portion at the time of molding the light guide body instead of screen-printing the dot pattern on the curved surface of the light guide body GLB. Matching with the dot pattern is very difficult and expensive.

Embodiment 2 FIGS. 3 (a) to 3 (c) are diagrams showing the configuration of a screen printing machine according to a second embodiment of the present invention and the operation of the screen printing machine from the start to the end of printing.

In this embodiment, the cam mechanism shown in FIG. 1 is not used as the mechanism 10 for moving the suction table 5 up and down, but two stepping motors 3 (or vertical slides) having screw portions 4 are used instead. At least 2 with axis
This is an example using one air cylinder). Further, as the material to be printed according to the present embodiment, as shown in FIG. 3, the wedge-shaped light guide GLB having a trapezoidal cross section is used, but the present invention is also applied to the light guide GLB having the curved surface shown in FIG. It goes without saying that you can do it.

The operation will be described below. (A) shows a state before printing (at the start of printing). A wedge-shaped light guide body GLB made of acrylic or the like, which is a material to be printed, is vacuum-sucked to the suction table 5. The suction table 5 connected to the stepping motor 3 having the screw portion 4 maintains the distance g between the light guide GLB immediately below the squeegee 8 and the screen 6.
Since the light guide body GLB has a wedge shape, in the state shown in FIG. 7A, the difference between the distances g ₁ and g ₂ between the left and right ends of the light guide body GLB and the screen 6 is large. Therefore, when the squeegee 8 moves horizontally as it is, the horizontally held screen 6 is extended downward, and the screen 6 is damaged,
Service life is reduced. Further, the printing accuracy is reduced. In addition,
When the screen 6 is tilted along the tilted printing surface of the wedge-shaped light guide GLB, the ink placed on the screen 6 flows and the printing accuracy deteriorates. In order to prevent this, in this embodiment, the stepping motor 3 having the screw portion 4 and the sequencer are used to electrically move the suction table 5 up and down to keep the distance g constant.

(B) shows a state in the middle of printing. The squeegee 8 is just the middle point. The stepping motor 3 connected to the suction table 5 via the screw portion 4 rotates, and the right end of the suction table 5 is lifted by the screw portion 4 to keep the distance g between the screen 6 and the light guide GLB constant. .

(C) shows the state at the end of printing. The squeegee 8 is moved up and down by the stepping motor 3 and the screw portion 4 until the squeegee 8 reaches the position where printing is completed.
The distance g between the light guide body GLB immediately below and the screen 6 is kept the same.

Thus, in synchronization with the movement of the squeegee 8 in the direction of the arrow, the suction table 5 is moved up and down by the stepping motor 3 and the screw portion 4, and the light guide G immediately below the squeegee 8 is moved.
The distance g between the LB and the screen 6 is always kept constant from the start to the end of printing. Therefore, as in the first embodiment of FIG. 1, it is possible to perform screen printing with high accuracy and without damaging the screen. In addition, the fixing portion of the screw portion 4 of the stepping motor 3 and the suction table 5 is,
The same structure as that shown in FIGS. 2A to 2C of the first embodiment may be used.

FIG. 5 is an exploded perspective view of a liquid crystal display module MDL incorporating a light guide GLB capable of printing a light diffusion dot pattern by a screen printer according to the present invention.

SHD is a shield case made of a metal plate (also called a metal frame), WD is a display window and INS1.
3 to 3 are insulating sheets, PCBs 1 to 3 are circuit boards (PCB1
Is the drain side circuit board, PCB2 is the gate side circuit board,
PCB3 is an interface circuit board), JN is a joiner that electrically connects the circuit boards PCB1 to PCB3, T
CP1, TCP2 are tape carrier packages, PNL
Is a liquid crystal display panel, GC is a rubber cushion, ILS is a light-shielding spacer, PRS is a prism sheet, SPS is a diffusion sheet, GLB is a light guide, RFS is a reflection sheet, and MCA is a lower case (molded case) formed by integral molding. ), LP is a fluorescent tube, LPC is a lamp cable, and GB is a rubber bush that supports the fluorescent tube LP.

FIG. 6A is a top view showing a state where the backlight BL (fluorescent tube LP, lamp cable LPC, rubber bush GB, light guide GLB) is housed and mounted in the lower case MCA, ( (b) is sectional drawing in the bb cutting line of (a).

The backlight BL for supplying light to the display panel PNL shown in FIG. 6 holds one cold cathode fluorescent tube LP, two lamp cables LPC of the fluorescent tube LP, the fluorescent tube LP and the lamp cable LPC. Two rubber bushes GB, a light guide GLB, a diffusion sheet SPS arranged in contact with the entire upper surface of the light guide GLB, a reflection sheet RFS arranged on the entire lower surface of the light guide GLB, and an entire upper surface of the diffusion sheet SPS. It is composed of a prism sheet PRS arranged in contact with and is housed in the lower case MCA. In addition,
IV is an inverter IV for driving the fluorescent tube LP connected to the tip of the lamp cable LPC.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it is needless to say that various modifications can be made without departing from the scope of the invention. . For example, the mechanism 10 for moving the suction table 5 shown in FIGS. 1 and 3 up and down is provided at the center of the left and right ends of the suction table 5, but three or more mechanisms 10 may be provided at appropriate places. It is possible. Further, as in FIGS. 1 and 3, one mechanism may be provided as long as it has a function of vertically moving both left and right ends of the suction table 5. Also, FIG.
As shown in FIGS. 1 and 3, the upper and lower slide shafts 2 and the screw portion 4 of FIG. 3 may be fixed to the suction table 5 on the lower surfaces (the central portions) of the left and right end portions of the suction table 5, respectively. As shown in FIG. 2C, the suction table 5 may be provided on both left and right side surfaces. Further, it is not always necessary to fix, and only contact may be performed if the suction table 5 makes a desired vertical movement by the vertical slide shaft 2 and the screw portion 4. Furthermore, in the above description, an example of printing on the bottom surface of the light guide body made of an acrylic plate or the like that constitutes the backlight incorporated in the liquid crystal display module has been described, but it has a curved surface, a sloped surface, or an irregular surface. It is needless to say that it can be applied to printing on the surface of the member, and can be applied to various printed materials.

[0040]

As described above, according to the screen printing machine of the present invention, it is possible to print on a curved surface, an inclined surface or an irregular surface with high accuracy and without damaging the screen.

[Brief description of drawings]

1A to 1C are diagrams showing a configuration of a screen printing machine according to a first embodiment of the present invention and an operation of the screen printing machine from the start to the end of printing.

FIG. 2A is a partial front view showing an example of details of a portion A (an upper end of a vertical slide shaft, which is fixed to a suction base) of FIG. 1A, and FIG. 2B is an arrow of FIG. The partial side view seen from B direction, (c) is a figure similar to (a) which shows the other structural example of A part.

3A to 3C are diagrams showing the configuration of the screen printing machine according to the second embodiment of the present invention and the operation of the screen printing machine from the start to the end of printing.

FIG. 4 is a perspective view of a light guide, a fluorescent tube, and a liquid crystal display panel showing a light diffusion dot pattern that can be printed by the screen printer according to the present invention.

FIG. 5 is a liquid crystal display module M incorporating a light guide GLB.
It is a disassembled perspective view of DL.

6A is a plan view showing a state in which a backlight including a light guide is housed in a lower case, and FIG. 6B is a sectional view taken along the line bb of FIG. 6A. is there.

[Explanation of symbols]

1a, 1b ... Cam, 2 ... Vertical slide shaft, 3 ... Stepping motor, 4 ... Screw part, 5 ... Adsorption base, 6 ... Screen (printing plate), 7 ... Screen frame, 8 ... Squeegee, 9 ... Ink, 10 ... Vertical movement mechanism of suction table, 11 ... Bearing, 1
2 ... Rotating shaft, 13 ... Fixed pin, GLB ... Light guide, DP ...
Dot pattern for light diffusion.

Claims (6)

[Claims] 1. A table for holding an object to be printed, a screen provided on the table and having predetermined micropores, and a screen which is in contact with the screen and moves from one end to the other end of the screen. A screen printing machine comprising: a squeegee for covering the ink placed on the screen; and a mechanism for moving the base up and down. 2. A table for holding an object to be printed, a screen which is provided substantially horizontally on the object to be printed and which is held on the table, and which has predetermined minute holes, and a screen which is in contact with the screen. Moving from one end to the other end of the screen, the ink placed on the screen is covered, and the squeegee of the squeegee is maintained so that the distance between the squeegee directly below the squeegee and the screen is constant. A screen printing machine having a mechanism for moving the table up and down in synchronization with the movement. 3. The mechanism for moving the table up and down comprises at least two vertical slide shafts whose upper ends are fixed to or in contact with both ends of the table, respectively, and the lower ends of the shafts are in contact with each other. The screen printing machine according to claim 1, wherein the screen printing machine is configured to include at least two cams having a predetermined shape and arranged. 4. The mechanism for moving the table up and down is configured to include at least two stepping motors having screw parts whose upper ends are fixed to or in contact with both ends of the table, respectively. The screen printing machine according to claim 1, wherein the screen printing machine is a screen printing machine. 5. The mechanism for moving the table up and down is configured to include at least two air cylinders having vertical slide shafts whose upper ends are fixed to or in contact with both ends of the table, respectively. The screen printing machine according to claim 1 or 2, characterized in that: 6. The screen printing machine according to claim 1, wherein the table has means for adsorbing the material to be printed on the table.