JPWO2014016966A1 - Screen printing machine - Google Patents

Abstract

Improves the utility of a screen printer that performs printing alternately with a pair of squeegees. A photoelectric sensor 140 is provided between the pair of squeegees 130 and is moved integrally with the mask 32. A pair of squeegees 130 are moved forward from the solder detection start position prior to the start of printing after completion of printing preparation or after interruption of printing. Meanwhile, the photoelectric sensor 140 projects light toward the mask 32 and outputs an ON signal if the solder 142 is present. The squeegee 130 to be printed first is determined based on the position of the solder 142 on the mask 32, and the squeegee 130 corresponding to the position of the solder 142 is located on either side of the mask 32 at the beginning of printing. 142 is moved, and the occurrence of blank printing is avoided. If there is no solder 142 on the mask 32 and at least one of its position and amount is inappropriate, a notification is given and the operator is required to take action.

Description

  The present invention relates to a screen printer, and more particularly to a screen printer that performs printing alternately with a pair of squeegees.

  Patent Document 1 below describes a screen printing machine that detects the state of cream-like solder on a screen mask and determines the sliding start position of the squeegee. In this screen printing machine, the cross-sectional area, maximum height, center position and width (dimensions in the direction parallel to the printing direction) of the cream-like solder forming the roll shape are detected, and based on these, the squeegee moves forward. The printing start position in each of the printing and the printing by the backward movement is determined as a position where the surface on which the solder of the squeegee is pressed comes into slight contact with the solder roll.

JP 2010-184359 A

  The present invention has been made against the background of the above circumstances, and an object thereof is to improve the practicality of a screen printing machine that performs printing alternately with a pair of squeegees.

The above-described problem is that the cream solder placed on the screen mask having a plurality of openings is alternately pushed in the forward direction and the backward direction by a pair of squeegees provided facing each other, and printed on the circuit board through the openings. (A) a screen printing machine (a) provided at a position adjacent to at least one of the squeegees in the moving direction of the pair of squeegees so as to be movable toward the screen mask and parallel to the screen mask together with the pair of squeegees A solder sensor that outputs a different signal between the state facing the screen mask and the state facing the solder, and (b) the pair of squeegees before the start of printing after completion of printing preparation or after interruption of printing, Before starting printing to move at least once within a preset range while being separated from the screen mask And (c) detecting the position of the creamy solder on the screen mask based on the output of the solder sensor while the squeegee is moved by the movement control unit before starting printing, and This is solved by including a printing start squeegee determining unit that determines which one of the pair of squeegees performs printing first based on the position.
The range of movement of the pair of squeegees by the movement control unit before starting printing may be set by an operator, or automatically based on the size of a screen mask installed in a screen printer or the size of a circuit board to be printed. It may be set, and may always be set to the maximum movable range. Further, the moving direction of the pair of squeegees by the movement control unit before starting printing may be determined in a direction from one moving end position where the pair of squeegees are actually stopped to the other moving end position, and is always determined. The direction may be determined.

Each of the pair of squeegees is positioned on the upstream side of the cream-like solder in the moving direction during printing, and moved in the opposite direction to perform printing. Therefore, the printing start positions of the pair of squeegees are separated in the squeegee movement direction of the screen mask, and the squeegee used for printing first depends on which printing start position the cream solder is located at when printing starts. Is decided. However, if the cream solder is at a position different from the planned position at the start of printing, and the squeegee that corresponds to the cream solder's planned position is the first squeegee to be used, the cream solder is pushed forward. Cannot be printed on the circuit board. This situation can be avoided if the operator confirms the actual position of the cream solder and specifies the squeegee to start printing first to start printing. If it is started, printing failure may occur.
On the other hand, according to the screen printing machine according to the present invention, prior to the start of printing, one of the pair of squeegees to be printed first is determined based on the detection of the position of the cream solder, and the cream solder is scheduled. Even if it is not, the squeegee corresponding to the actual position of the cream solder is automatically determined as the one to be printed first. The occurrence of printing defects is avoided at any position on the mask.
If a photoelectric sensor is used as a solder sensor, solder detection can be performed at a low cost. For example, a camera may be used to detect solder based on color, shape, etc. Good. The solder sensor may detect not only the position of the solder but also the amount of solder (at least one of width and height).
If the solder sensor is provided between the pair of squeegees, the gap between the pair of squeegees can be used to avoid an increase in size of the moving portion including the pair of squeegees and the solder sensor.

1 is a side view schematically showing a screen printing machine according to an embodiment of the present invention. It is a top view which shows the mask holding | maintenance apparatus of the said screen printer. It is a top view which shows the squeegee apparatus of the said screen printer. It is a perspective view which shows the squeegee raising / lowering apparatus of the said squeegee apparatus. It is a perspective view which shows the squeegee head of the said squeegee apparatus. It is a side view which shows roughly the photoelectric sensor provided with the said squeegee head. It is a flowchart which shows the printing routine memorize | stored in ROM of the computer which comprises the main body of the control apparatus which controls the said screen printer. It is a flowchart which shows the solder detection routine among the said printing routines. It is a figure explaining the detection of the solder in the said screen printer.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the present invention can be implemented in a mode in which various modifications are made based on the knowledge of those skilled in the art, in addition to the following embodiments.

  A screen printing machine 10 (hereinafter, abbreviated as a printing machine 10) according to an embodiment of the present invention is schematically shown in FIG. The screen printing machine is configured in the same manner as the screen printing machine described in Japanese Patent Application Laid-Open No. 2011-230353 except for the part related to the present invention, and will be described briefly.

  As schematically shown in FIG. 1, the printing machine 10 includes a printing machine main body 12, a substrate transport device 14, a substrate holding device 16, a mask holding device 18, a squeegee device 20, and a control device 22. The substrate transport device 14 transports the circuit board 30 (see FIG. 6) in a horizontal posture in a direction perpendicular to the paper surface in FIG.

  A substrate holding device 16 is provided in the middle of the substrate transfer path by the substrate transfer device 14, and holds the circuit board 30 in a horizontal posture. The substrate holding device 16 includes, for example, a substrate supporting device that supports the circuit board 30 from below by a support member, and a clamp device that clamps the circuit board 30 from both sides perpendicular to the substrate transport direction. The circuit board 30 that has been lifted and lowered by the apparatus is moved closer to and away from a screen mask 32 (hereinafter abbreviated as mask 32) held by the mask holding apparatus 18. In this embodiment, the board conveyance direction is the left-right direction, and the plane is parallel to the solder printing surface of the circuit board 30 held by the board holding device 16 and is perpendicular to the board conveyance direction in the horizontal plane. And The printing machine 10 has one side in the front-rear direction as a front surface, and a cover (not shown) that covers the printing machine body 12 is opened so that an operator can replace the mask 32 or supply solder from the front side. ing. The front side of the printer main body 12 is the front side, the opposite side, and the back side is the rear side.

  In the present embodiment, as shown in FIG. 2, the mask 32 has a plurality of openings 44 formed in a printing region 42 of a metal, for example, stainless steel sheet. It is stretched on the mask frame 48. The mask 32 and the mask frame 48 are square or rectangular, and the mask 32 is stretched on the mask frame 48 in a state where the center thereof coincides with the center of the mask frame 48. The size of the mask frame 48 is common to a plurality of types of circuit boards. The sizes of the mask 32 and the print area 42 may differ depending on the type of the circuit board 30 or may be common.

  The mask holding device 18 includes a mask frame receiver 60 and a position adjusting device 62 as shown in FIG. The mask frame receiver 60 includes a pair of receiving portions 64 that receive the mask frame 48 from below, and a plurality of air cylinders 66 as a fixing device that presses and fixes the mask frame 48 to them.

  The position adjusting device 62 is provided between the printing press main body 12 and the mask frame receiver 60. The position adjustment device 62 includes two longitudinal adjustment units 70 that are separated from each other in the lateral direction, one lateral adjustment unit 72 that is separated from the two longitudinal adjustment units 70 in the longitudinal direction, and the one lateral adjustment. And a single floating support unit 74 separated from the unit 72 in the left-right direction. By adjusting the position of the mask frame receiver 60, the mask 32 held by the mask frame receiver 60 and the substrate holding device 16 are held. The relative positional deviation with respect to the circuit board 30 is eliminated. Further, in the printing machine 10, each of the circuit board 30 and the mask 32 is controlled by controlling the stop position of the circuit board 30 transport by the board transport device 14 and moving the mask 32 in the front-rear direction by the position adjusting device 62. Printing is performed with the centers coincident.

  In this embodiment, the squeegee device 20 includes a pair of squeegee heads 80 and a squeegee moving device 82 as shown in FIGS. A squeegee moving device main body 84 of the squeegee moving device 82 is fixed to the upper surface of the mask frame receiver 60 as indicated by a two-dot chain line in FIG. As shown in FIG. 3, a squeegee slide 86 is supported on the squeegee moving device main body 84 so as to be movable in the front-rear direction, and is guided by the two guides 90 constituting the guide device by the squeegee slide driving device 88. While moving in the horizontal direction. In the printing machine 10, the front-rear direction is the squeegee movement direction, which is the printing direction.

  The squeegee slide driving device 88 in this embodiment includes a feed screw 92 that is rotatable on the squeegee moving device main body 84 and is not movable in the axial direction, and a nut that is fixed to the squeegee slide 86 and screwed into the feed screw 92. 94 and an electric motor 96 that rotationally drives the feed screw 92. The feed screw 92 is preferably a ball screw, and the electric motor 96 is preferably an electric motor capable of controlling the rotation angle, such as a servo motor. The same applies to the feed screw and the electric motor described below.

  As shown in FIG. 4, the squeegee slide 86 is provided with a first elevating member 100 that can be raised and lowered via the load cell 102 and the compression coil spring 104, and is biased toward the squeegee slide 86 by the tension coil spring 106. The force with which the squeegee presses the mask 32 against the circuit board 30 is adjusted.

  A pair of second elevating members 110 are provided on the first elevating member 100 so as to be able to move up and down, and are individually moved up and down by the elevating drive device 114 while being guided by the guide device 112, and driven up and down. A squeegee lifting device 115 is configured together with the device 114. The guide device 112 includes a guide rod 116 and a guide sleeve 118, and the elevating drive device 114 is capable of rotating on the first elevating member 100 and moving in the axial direction while being fixed to the second elevating member 110. It includes a nut 122 that is impossible, a pulley 124 that rotates the nut 122, a belt 126, and an electric motor 128.

  Each of the pair of squeegee heads 80 includes a squeegee 130 and a squeegee holding device 132 as shown in FIG. 5 and is detachably attached to the second elevating member 110, and is moved integrally by the squeegee moving device 82. It is done. The squeegee 130 is held by the squeegee holding device 132 in a forward inclined posture inclined upward toward the downstream side in the moving direction during printing. Each squeegee 130 of the pair of squeegee heads 80 attached to the second elevating member 110 has a longitudinal direction parallel to the left-right direction and a direction parallel to the printing direction or the front-rear direction, as schematically shown in FIG. In addition to being lined up, they are symmetrical with respect to a plane perpendicular to the mask 32 and parallel to the left-right direction, and face each other. In some cases, of the pair of squeegees 130, the front squeegee 130 is referred to as a front squeegee 130, and the rear squeegee 130 is referred to as a rear squeegee 130.

  As schematically shown in FIG. 6, a photoelectric sensor 140 is provided between the pair of second elevating members 110 of the first elevating member 100 and between the pair of squeegees 130 in the front-rear direction. And moved together with the pair of squeegees 130 in the front-rear direction in parallel to the mask 32. The photoelectric sensor 140 is a kind of non-contact sensor, and is a reflection type in this embodiment. Since the reflective photoelectric sensor 140 is a known sensor, a detailed description thereof will be omitted. However, a projector that projects light onto a spot-shaped region having a predetermined size on the mask 32 and the region of the mask 32 described above. And a light receiver that receives the reflected light from the light source, and is provided downward and toward the mask 32.

  The light receiver outputs different signals depending on whether the amount of received light is larger than the set amount or less than the set amount. In this embodiment, the light receiver is placed on the surface of the mask 32 and the mask 32. Corresponding to the difference in reflectance from the surface of cream solder 142 (hereinafter abbreviated as solder 142), two types of signals, ON and OFF, are output, and an OFF signal is output when facing the mask 32. In the state facing the solder 142, an ON signal is output. The solder 142 is placed in a strip shape that is long in the left-right direction on the part of the mask 32 that is out of the print area 42 by the operator.

  As shown in FIG. 1, the control device 22 is composed mainly of a computer 150 including a CPU, a ROM, a RAM, and a bus connecting them, and controls drive sources and the like of various devices constituting the printing press 10. The computer 150 is connected to an encoder 152 that is a rotational position detector for detecting the rotational position of the electric motor 96 or the like (one is representatively shown in FIG. 1), and the detection signal of the photoelectric sensor 140 or the like. Entered.

  Further, a display screen 154 is connected to the computer 150 via a control circuit (not shown), and a display device 156 that is a notification device is configured in cooperation with the control circuit. The display device 156 displays information, instructions, and the like on the display screen 154, and is configured such that instructions for printing and the like are input by an operator based on the display on the display screen 154. Is also made to work. An input device may be provided separately from the display device. The notification device may perform notification by sounding a buzzer, lighting and blinking a lamp, transmitting error data to a personal digital assistant known as PDA (Personal Digital Assistant) or a personal computer, and displaying it. The RAM and ROM store a printing program for printing the cream solder on the circuit board 30, a printing routine represented by flowcharts in FIGS. 7 and 8, and the like.

  In the printing machine 10 configured as described above, the pair of squeegees 130 are alternately brought into contact with the mask 32 to push the solder 142 and print on the circuit board 30 through the openings 44. The front squeegee 130 is moved from the front to the rear, the solder 142 is moved from the position where the printing area 42 of the mask 32 is removed from the front side to the position where it is removed rearward, and the rear squeegee 130 is moved from the rear to the front. Then, the solder 142 is moved from the position where the printing area 42 of the mask 32 is removed from the rear side to the position where it is removed from the front side. The print start positions of the front and rear squeegees 130 are separated in the front-rear direction.

  If the position of the solder at the start of printing after the completion of printing preparation in the printing machine or at the start of printing after interruption of printing is uniformly assumed, and depending on which one of the pair of squeegees is used for printing first, Printing failure may occur. For example, when it is assumed that the worker puts solder on the front side of the mask and the front squeegee is determined to be the first squeegee to perform printing, the setup change is performed and printing is started after the printing preparation is completed. If the worker puts the solder on the back side at the end of work, etc., when the worker clears the solder and then turns off the power to interrupt printing and then resumes printing after turning on the power Even if the squeegee is moved, the solder is not fed, and blank printing that does not print on the circuit board occurs. Also, when the power is turned off automatically or due to an operator's operation of an emergency stop button due to a malfunction of the printing press, the solder remains on the mask, and if it is behind the mask, Printing occurs. Even when it is not assumed that the solder is placed on the front side, printing failure may occur. For example, when printing is temporarily interrupted without turning off the power, the position of the solder immediately before the interruption is memorized, and when the squeegee that performs printing first can be determined when printing resumes accordingly, washing, etc. If the mask is exchanged for the purpose, and the solder is placed at a position different from the position stored after the exchange, blank printing occurs. Even if the operator confirms the position of the solder at the start of printing and decides the squeegee for printing first, printing failure may occur due to forgetting to decide. Therefore, in the present printing machine 10, the position of the solder 142 is detected prior to the start of printing after completion of printing preparation or after interruption of printing, and the first one of the pair of squeegees 130 to be printed is determined. Yes.

  At the time of printing, a printing routine is executed, and in step 1 (hereinafter abbreviated as S1; the same applies to other steps), it is determined whether or not an operation start command has been input by the operator. The operation start command is, for example, from the display screen 154 when the preparation for printing is completed and solder printing on the set number of circuit boards 30 is started or when the printing operation is interrupted and resumed. Is input.

  If an operation start command is input, solder detection is performed (S2). At the time of detection, the pair of squeegees 130 are separated from the mask 32, and solder detection is performed according to the routine shown in FIG. 8. First, the pair of squeegees 130 are moved to the solder detection start position (S21). In the present embodiment, as shown in FIG. 9A, the solder detection start position is a position where the photoelectric sensor 140 is located above the rear end of the mask 32, and as shown in FIG. The end position is a position where the photoelectric sensor 140 is located above the front end of the mask 32. The position of the mask 32 is obtained by the size of the mask 32 and the holding position by the mask holding device 18. The dimensions of the mask 32 and the size of the print area 42 are obtained from data relating to the mask 32 included in the print program. The supply of solder is performed from the front side of the printing machine 10 which is easy to work, and if solder is not placed on the mask 32, it is generally placed on the front side of the mask 32. The squeegee 130 is positioned on the rear side of the mask 32 so as not to disturb the operation. Therefore, if the solder detection start position is set at the rear end of the mask 32 and the solder detection end position is set at the front end of the mask 32, the detection is started without changing the position in the front-rear direction of the pair of squeegees 130, and printing. It is normal to be able to start. The current position of the pair of squeegees 130 is obtained based on the detection value of the encoder 152 of the electric motor 96 and is moved from that position to the solder detection start position.

Then, S22 is executed, and the pair of squeegees 130 are moved forward together with the photoelectric sensor 140 as shown in FIG. During this movement, the light projector of the photoelectric sensor 140 projects light toward the mask 32, and an output signal is input to the computer 150 based on the amount of light received by the light receiver. As shown in FIG. 9C, the pair of squeegees 130 are moved to the solder detection end position, and the solder detection ends.
The position where the photoelectric sensor 130 is located above the front end of the mask 32 may be the solder detection start position, and the position located above the rear end of the mask 32 may be the solder detection end position. Of the position where the photoelectric sensor 130 is located above the front end of the mask 32 and the position located above the rear end, the position closer to the position where the pair of squeegees 130 is actually located is the solder detection start position, which is far away. This position may be the solder detection end position.

  After the solder is detected, it is determined whether or not there is the solder 142 based on the data acquired in S2 (S3). As shown in FIG. 9 (d), the signal of the photoelectric sensor 140 is turned ON if the solder 142 is present, and the position of each photoelectric sensor 140 is turned ON when changing from OFF to ON and when changing from ON to OFF. Along with the signal information, it is stored in a solder detection data memory provided in the RAM and constituting the storage means. The position of the photoelectric sensor 140 is obtained based on the detection value of the encoder 152 of the electric motor 96.

  In S3, it is determined whether or not an ON signal is input. If the ON signal is obtained and the solder 142 is present, it is determined whether or not the position and amount are both appropriate (S4). In the present embodiment, the position of the solder 142 is acquired in the width direction of the solder 142 (direction parallel to the front-rear direction). The position of the photoelectric sensor 140 while the output signal is ON represents the position of the solder 142, and the position from the position when the signal changes from OFF to ON to the position when the signal changes from ON to OFF is the position of the solder 142. It is assumed to be a position. The amount of the solder 142 is also acquired in the width direction in this embodiment, and the interval between the two positions where the signal has changed is acquired as the width of the solder 142.

  Whether or not the position of the solder 142 is appropriate is determined by whether or not the solder 142 is located in a region set in advance on the mask 32. The areas where the solder 142 should be positioned at the time of the first printing performed after the completion of the printing preparation and after the interruption of the printing are set in advance before and after the mask 32, respectively. In this embodiment, the printing of the squeegee 130 is started at the time of the first printing. The position is set on the basis of the contact position with respect to the mask 32 and the print area 42, and is set to an area that is out of the print area 42 in the printing direction and does not bite into the solder 142 when the squeegee 130 is lowered. If printing is started in a state where at least a part of the solder 142 is in the printing area 42, the solder 142 is not normally fed, so that an opening 44 that is not sufficiently filled with the solder 142 is generated, while the squeegee is squeezed. If the solder 130 bites into the solder 142 when descending, the solder 142 adheres to the back surface of the squeegee 130, and the solder 142 attached to the back surface remains above the opening and is printed excessively. This is because the substrate 30 may be produced.

  Whether or not the amount of the solder 142 is appropriate is determined based on whether or not the width of the solder 142 is equal to or greater than a preset minimum width and equal to or less than a preset maximum width. If the width is smaller than the set minimum width and printing is performed as it is, the amount of solder filling into the opening 44 may be insufficient, and if it is larger than the maximum width, the amount is excessive, exceeding the minimum width If it is less than the maximum width, the amount is appropriate.

  In addition, although the change from OFF to ON of the output signal of the photoelectric sensor 140 was obtained, when the movement of the squeegee 130 was completed without obtaining the change from ON to OFF, at least the position of the solder 142 was inappropriate. It is said. This is because, for example, this occurs when the solder 142 is placed in a state of protruding from the mask 32 to the mask holding sheet 46 side.

  If both the position and the amount of solder are appropriate, the squeegee 130 to be printed first is determined from the pair of squeegees 130 (S5). If the solder 142 is on the front side of the printing area 42, the front squeegee 130 is the squeegee that performs printing first, and if it is on the rear side, the rear squeegee 130 is the squeegee that performs printing first. Therefore, regardless of whether the operator places the solder 142 on either the front side or the rear side of the mask 32, the squeegee 130 corresponding to the solder will first print.

  At the time of printing, the squeegee 130 determined as the first squeegee to be printed is moved to the printing start position, lowered and brought into contact with the mask 32, moved along the mask 32, and the solder 142 is moved. Printing is performed by pushing into the opening 44 (S6). If printing is not interrupted, S6 to S8 are repeatedly executed until the number of printed sheets reaches the set number of sheets and printing is completed.

  As a result of the solder detection, if the ON signal is not obtained and there is no solder 142 on the mask 32, the display screen 154 is informed that there is no solder 142, and the execution of the routine ends (S9). . Based on this notification, the operator checks the mask 32, and if there is no solder 142, puts it on and inputs an operation start command. In addition, when the worker erroneously places the solder 142 on the mask holding sheet 46, no ON signal is obtained, and the worker places the solder 142 on the mask 32 and inputs an operation start command. Accordingly, it is possible to avoid a situation in which the operation of the printing press 10 is started when there is no solder 142 on the mask 32.

  If there is solder 142 on the mask 32 but at least one of its position and amount is inappropriate, this is displayed on the display screen 154 and notified (S9), and the routine is executed after the notification. Ends and waits for input of operation start command. According to the notification, if the position of the solder 142 is inappropriate, the operator removes the solder placed on the mask 32 and puts it back on an appropriate position. If the amount of the solder 142 is insufficient, the worker replenishes the solder 142. If the amount is too large, remove some and enter the start of operation. As a result, the solder 142 is present, but the first squeegee to be printed is determined with at least one of the position and the amount being inappropriate, and printing is started, printing failure occurs, or the solder 142 is placed on the back of the squeegee 130. Is avoided.

  If there is no solder 142 or at least one of the position and the amount is inappropriate, the step S2 and the subsequent steps are not performed until the operation start command is input, and the operation of the printing press 10 is substantially automatically started. The above-mentioned inconvenience is surely avoided. Further, when the operator inputs an operation command again without performing an appropriate process based on the notification, only S2, S3 and S9, or S2 to S4 and S9 are repeatedly executed, and the steps after S5 Is not executed, and the start of the operation of the printing press 10 is substantially prohibited automatically, and the occurrence of the inconvenience is surely avoided.

  When printing is interrupted without turning off the power of the printing press 10, the determination in S7 is YES and the execution of the routine ends. In this case, only S1 is executed until an operation start command is input for resuming printing, printing is not resumed, and operation resumption is prohibited. And if an operation start command is inputted, the steps after S2 will be executed. Therefore, for example, even when printing is interrupted for mask replacement and the position of the solder 142 in the front-rear direction is different before and after the replacement, the actual position of the solder 142 is detected and printing is performed first after resumption. By determining the squeegee 130, it is possible to avoid the situation where the squeegee 130 to be printed first is determined based on the position of the solder 142 at the end of printing immediately before the interruption and the solder 142 is not printed on the circuit board 30. The When printing is interrupted due to replenishment of solder, since the amount of solder 142 actually placed on the mask 32 is increased by replenishment, the approximate position of the solder 142 before and after the interruption of printing does not change. At least one of the quantities may not be appropriate and the detection avoids the occurrence of defects.

  When printing is interrupted when the power is turned off, such as when printing is interrupted at the end of work or due to a malfunction of the printing press 10, execution of the routine ends. Next, in a state where the power is turned on, S1 is executed to wait for the input of an operation start command, and the detection of the solder 142 or the like is performed by the input, thereby preventing the occurrence of defective printing.

  At the start of printing after completion of printing preparation or after interruption of printing, an operation start command is input by an operator. Therefore, prior to the start of printing, solder detection and determination of the squeegee 130 to be printed first are automatically performed. Therefore, regardless of the solder 142, the occurrence of printing failure due to forgetting to decide the squeegee 130 to be printed first is surely avoided. Further, the notification allows the operator to quickly cope with the absence of the solder 142 and start printing.

  As is apparent from the above description, in this embodiment, the part of the computer 150 that executes S2 constitutes the pre-print start movement control, the part that executes S5 constitutes the print start squeegee determining unit, and the mask 32. If the solder 142 is not present and at least one of the position and amount of the solder 142 is inappropriate, the printing routine is terminated and the first squeegee to be printed is input until an operation start command is input. The configuration in which printing is not performed constitutes the operation start prohibiting unit.

  If the pair of squeegees are located at the stop position at the end of the last print immediately before the interruption after the print interruption, the pair of squeegees are moved in the opposite direction from the stop position at the end of the last print. Solder detection may be performed. At this time, the print end position may be the solder detection end position, or a position different from the print end position may be the solder detection end position.

  The solder sensor may be provided at a position adjacent to one of the pair of squeegees.

  Further, the printing may be performed by moving the squeegee in a direction parallel to the substrate transport direction.

  10: Screen printer 32: Screen mask 130: Squeegee 140: Photoelectric sensor 142: Cream solder

Claims (5)

A screen printer for printing a solder paste placed on a screen mask having a plurality of openings alternately in the forward direction and the backward direction by a pair of squeegees provided facing each other and printing on the circuit board through the openings. Because
A state in which the pair of squeegees are provided at positions adjacent to at least one of the squeegees so as to be movable toward the screen mask and parallel to the screen mask together with the pair of squeegees. A solder sensor that outputs different signals depending on the state facing the solder;
Prior to the start of printing after completion of printing preparation or after interruption of printing, the pair of squeegees are moved away from the screen mask and moved at least once within a preset range, and a movement control unit before printing starts,
The position of the cream solder on the screen mask is detected based on the output of the solder sensor while the squeegee is moved by the movement control unit before starting printing, and the pair of the pair is determined based on the detected position. A screen printing machine comprising: a printing start squeegee determining unit that determines a squeegee to be printed first.   The screen printing machine according to claim 1, wherein the solder sensor is provided between the pair of squeegees.   The screen printing machine according to claim 1 or 2, wherein the movement control unit before starting printing automatically operates when an operation start command is input by an operator while the screen printing machine is stopped.   And a notifying device for notifying that there is no cream-like solder on the screen mask when the output of the solder sensor does not change while the squeegee is moved by the movement control unit before starting printing. The screen printer according to any one of claims 1 to 3.   Furthermore, an operation start prohibiting unit that automatically prohibits the start of operation of the screen printing machine when the output of the solder sensor does not change while the squeegee is moved by the movement control unit before starting printing is included. The screen printer according to any one of claims 1 to 4.

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