Screen printer

A screen printer in which a squeegee is lowered towards a screen when the internal pressure of a second air chamber of a pressing force adjusting air cylinder is decreased. A control section performs control of an air regulator based on response times from starting control of the air regulator to decrease or increase the internal pressure of the second air chamber until a value detected by a pressure sensor reaches a target value of the internal pressure.

TECHNICAL FIELD

The present application relates to a screen printer that presses a squeegee against a screen and a device that controls the pressing force of the squeegee.

BACKGROUND ART

Screen printers that print solder paste onto a printed circuit board are known (for example, patent literature 1). With this type of screen printer, with a squeegee contacting a screen provided with multiple holes, the screen and the squeegee are moved relatively such that solder paste on the screen is printed onto a circuit board through the holes. Here, the pressing force of the squeegee on the screen affects printing quality.

Specifically, for example, if the pressing force is insufficient, solder paste will be printed in a state raised from the squeegee side openings of the holes provided in the screen, leading to cases in which adjacent solder paste deposits are undesirably connected to each other. To counter this problem, with the screen printer disclosed in patent literature 1, a compression coil spring that biases the squeegee towards the screen is provided between the squeegee and a frame that holds the squeegee, such that printing is not performed with the solder paste raised.

Conversely, if the pressing force is too great, the squeegee slices solder paste entered inside the holes, which may lead to problems such as insufficient printing quantity or lowered longevity of the squeegee or screen. For this problem, the screen printer disclosed in patent literature 1 is provided with a load sensor for detecting the load applied to the squeegee. As a load applied to the squeegee, in addition to the total weight of a member that moves together with the squeegee when the squeegee approaches and separates from the screen, there is the biasing force of the compression coil spring. The screen printer is provided with an air cylinder that acts on the squeegee with a force in a direction against the biasing force of the compression coil spring, with the pressing force being adjusted by controlling the air cylinder pressure based on an output value of a load sensor.

CITATION LIST

Patent Literature

SUMMARY

However, with the above screen printer, a dedicated sensor or the like for detecting the pressing force of the squeegee on the screen is required. Also, in order to accurately detect the load applied on the squeegee, the load sensor must be provided at a position appropriate for the total weight of the member that moves together with the squeegee and the biasing force of the compression coil spring, without being affected by operation that moves the squeegee. Thus, with the above screen printer, in order to provide a dedicated sensor, the configuration of the frame that holds the squeegee and the like is made complex, and manufacturing costs are increased.

The present disclosure takes account of the above problems and an object thereof is to provide a screen printer that allows the pressing force of a squeegee on a screen to be adjusted accurately while having a simple configuration, and that reduces manufacturing costs of the screen printer.

A screen printer disclosed herein takes account of the above problems, and comprises: a screen including multiple holes; a squeegee that slides on the screen so as to print printing material onto a target object through the holes of the screen; a fluid pressure cylinder that biases the squeegee in a direction either towards or away from the screen based on internal pressure of a cylinder housing; a pressure sensor that detects the internal pressure of the cylinder housing; and a control section that controls the internal pressure based on a response time, which is a time from starting control to change the internal pressure by supplying or removing a specified amount of fluid per unit of time with respect to the fluid pressure cylinder to a detection value of the pressure sensor reaching a target value.

Advantageous Effects

A screen printer according to technology disclosed herein allows the pressing force of a squeegee on a screen to be adjusted accurately while having a simple configuration, and reduces manufacturing costs of the screen printer.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present disclosure is described with reference to the figures.FIG. 1is a front view of an embodiment, solder paste printer100. As shown inFIG. 1, solder paste printer100(also referred to as “printer”) is a device that prints solder paste (not shown) on screen10(refer toFIG. 2) onto printed circuit board20using squeegee120. In the descriptions below, as shown inFIG. 1, the direction in which squeegee120moves is referred to as the Y-axis direction (the left-right direction inFIG. 2), and the direction perpendicular to the Y-axis direction in a horizontal plane of screen10is referred to as the X-axis direction (the direction coming straight out of the page inFIG. 2).

FIG. 2is a side view of printer100. Screen10shown inFIG. 2is provided with multiple holes (not shown) that pierce screen10in the thickness direction (the up/down direction inFIG. 2), and the circumferential edges of screen10are fixed to a screen frame, which is not shown. The screen frame is loaded on a screen support table the position of which is fixed, and is fixed to the screen support table by a fixing device after being positioned in the X-axis direction and Y-axis direction by a positioning device. Printer100, after conveying printed circuit board20in the X-axis direction under screen10using a board conveyor, raises/lowers printed circuit board20using a raising/lowering device such that printed circuit board20contacts screen10, or is separated from screen10. Printed circuit board20is made to be in contact with the lower surface of screen10during solder paste printing. After solder paste printing, printed circuit board20is unloaded by the board conveyor. Note that, for convenience of understanding, screen10and printed circuit board20are shown closer to squeegee120inFIG. 2than they are in actuality.

Printer100includes a squeegee moving device, which is not shown. The squeegee moving device includes a Y-axis slide, not shown, that is held to be movable in the Y-axis direction, and the Y-axis slide is moved in the Y-axis direction by servo motor34(refer toFIG. 4) being driven. Frame38is provided on the Y-axis slide. Two sets of squeegee units40(refer toFIG. 2) are provided on frame38. Frame38is moved in the Y-axis direction together with the Y-axis slide by a squeegee moving device. The two sets of squeegee units40are provided at symmetrical positions in the Y-axis direction and have the same configuration. One of the squeegee units40is described below as a representative example.

As shown inFIG. 2, squeegee raising/lowering air cylinder42is provided on frame38facing downwards. Cylinder housing44of squeegee raising/lowering air cylinder42is fixed with respect to frame38. Piston rod46of squeegee raising/lowering air cylinder42protrudes downwards from cylinder housing44and is inserted into through-hole48formed in frame38.

Pressing force adjustment air cylinder56is provided between each of cylinder housings44of the two sets of squeegee units40in the Y-axis direction. With cylinder housing64of pressing force adjustment air cylinder56, first air chamber72is formed on an upper side of piston62, and second air chamber74is provided on a lower side of piston62. Piston rod58of piston62protrudes downwards from inside cylinder housing64, with a tip section thereof fixed to frame38.

No seal member is provided at the section at which piston62and cylinder housing64slide by each other; instead, the clearance between piston62and cylinder housing64is smaller than usual, such that a practically sealed state is achieved. Two toric clearance grooves76are formed in the outer circumferential surface of piston62. Also, two toric clearance grooves78are formed in the through-hole of cylinder housing64through which piston rod58is inserted. Accordingly, piston62slides smoothly even though the clearance with cylinder housing64is small. Also, compression coil spring86is provided between frame38and cylinder housing64in a vertical direction, such that frame38is biased downwards.

An end of piston rod46of squeegee raising/lowering air cylinder42inserted into through-hole48provided in frame38is connected to support member102. Straight line moving member104is fixed to a lower surface of support member102. Support shaft106is held by straight line moving member104. Swing member108is swingably held at the center of support shaft106by support shaft106in the Y-axis direction. Squeegee holding member118of print head116is attached to a lower surface of swing member108. With print head116, squeegee120is attached to squeegee holding member118. Print head116is swingable together with swing member108, and raisable by squeegee raising/lowering air cylinder42and pressing force adjustment air cylinder56.

As shown inFIG. 1, a pair of straight guide rods124are provided on an upper surface of straight line moving member104separated in the X-axis direction. Guide rods124are slidably engaged in the axis direction with two guidance tubes126provided vertically on frame38, and guide straight line moving member104, swing member108, and squeegee120in the raising/lowering direction.

Squeegee holding member118is a substantially rectangular plate, with the direction perpendicular to the main surface arranged to be the Y-axis direction, and squeegee120attached so as to be detachable. Squeegee120, for example, made from rubber or metal (for example, stainless steel), is a substantially rectangular plate, and is held by squeegee holding member118so that the main surface faces the Y-axis direction. Squeegee120is held by squeegee holding member118in a state tilted with respect to the horizontal surface of screen10(refer toFIG. 2).

Adjusting the Pressing Force of Squeegee120on Screen10

As shown inFIG. 3, air is supplied to second air chamber74of cylinder housing64from air regulator96via opening64A of cylinder housing64. Piston62of cylinder housing64is raised/lowered based on the internal pressure of second air chamber74. Air regulator96is connected between air source98and second air chamber74. Air regulator96supplies air of a predetermined pressure value supplied from air source98to second air chamber74after adjusting the pressure based on control of control section148. The internal pressure of second air chamber74changes as air is supplied or removed based on the pressure of air supplied from air regulator96. Also, pressure sensor114that detects the internal pressure of second air chamber74is provided between air regulator96and cylinder housing64. Pressure sensor114outputs a detection result to control section148. Note that,FIG. 3shows a state in which printing is not being performed, with items raised to an upper end position. Control section148, for example, controls air regulator96such that air with a pressure higher than atmospheric pressure is supplied to second air chamber74, thereby raising squeegee120to the upper end position ofFIG. 3.

As shown inFIG. 4, control section148includes processing circuit PU140, ROM142on which a control program and the like is memorized, working memory RAM144, with these items being connected by bus146. Input interface150is connected to bus146, and is used to enter the internal pressure value of second air chamber74detected by pressure sensor114. Also, multiple drive circuits, drive circuits156to158, are connected to bus146via output interface154. Control section148controls servo motor34via drive circuit156. Also, control section148controls air regulator94that adjusts the pressure of air supplied to each squeegee raising/lowering cylinder42via drive circuit157. Further, control section148controls air regulator96via drive circuit158.

Next, printing operation of printer100is described. With the present embodiment of printer100, printing is performed alternately by two sets of squeegee units40. Control section148controls a squeegee moving device (servo motor34) such that the two sets of squeegee units40are moved in the Y-axis direction from one side to the other. When moving squeegee unit40, control section148lowers squeegee120of the squeegee unit40positioned at the upstream side in the moving direction such that squeegee120contacts screen10with the desired pressing force. Squeegee unit40is moved along screen10and as solder paste loaded on screen10is scraped by squeegee120, solder paste is printed onto printed circuit board20via the holes provided in screen10. Here, for the squeegee unit positioned at the downstream side, piston rod46of squeegee raising/lowering air cylinder42and cylinder housing64of pressing force adjustment air cylinder56are moved to the upper end position, such that squeegee120does not contact screen10. When printer100completes printing, printed circuit board20for which printing has been completed is unloaded and the next printed circuit board20is loaded. Further, printer100, as well as raising the squeegee120that was just used for printing, lowers the squeegee120that was not just used for printing such that their respective positions are switched, and then performs printing by moving squeegee unit40the opposite direction in the Y direction.

FIG. 5is a conceptual view showing the state before the squeegee contacts the screen. Note that, as described above, with printer100of the present embodiment, of the squeegees120, while printing is being performed with one of the squeegees120, the other squeegee120is held at a raised end position. Descriptions below are giving largely based on the squeegee unit40being used for printing. Control section148, when lowering squeegee120, first drives air regulator94corresponding to squeegee raising/lowering air cylinder42(refer toFIG. 1) via drive circuit157, thereby lowering squeegee120. Squeegee raising/lowering air cylinder42lowers squeegee120to a position slightly above screen10(for example, a position 3 mm higher than screen10).

Next, control section148lowers squeegee120using pressing force adjusting air cylinder56. Pressing force adjusting air cylinder56makes force from piston rod58act on frame38against the biasing force of compression coil spring86. The force that pressing force adjusting air cylinder56applies to frame38acts on squeegee120via squeegee raising/lowering air cylinder42, straight line moving member104, squeegee holding member118, and the like. The force that pressing force adjusting air cylinder56applies to frame38is smaller the smaller the internal pressure of second air chamber74. Here, force FC of the following equation acts on squeegee120.
FC=FA+W−FB(1)

In the above equation, FA is the biasing force in the downward direction due to compression coil spring86. W is the total weight of each member raised/lowered by pressing force adjusting air cylinder56(frame38, squeegee raising/lowering air cylinder42, support member102, straight line moving member104, swing member108, support shaft106, squeegee holding member118, and squeegee120). FB is the upwards force that pressing force adjusting air cylinder56applies to squeegee120against the biasing force of compression coil spring86.

Control section148controls regulator96to decrease the internal pressure of second air chamber74. FB decreases as the pressure of second air chamber74lowers, thus squeegee120is lowered by force FA of compression coil spring86. Squeegee120stops when the upward and downward forces are equal (when force FC is zero). Control section148sets the time from starting the instruction of decreasing the pressure to air regulator96until a value detected by pressure sensor114reaches a target value as “response time”, and the state of squeegee120contacting screen10or squeegee120separating from screen10is detected based on the response time.

In detail, force FA of equation (1) above is represented by the following equation.
FA=k×L(2)

In equation (2), k is the spring constant of compression coil spring86. L is the length in the vertical direction of compression coil spring86. Further, force FB of equation (1) above is represented by the following equation.
FB=S×P(3)

In equation (3), S is the cross section area of cylinder housing64(the surface ara when looking at piston62inside cylinder housing64from one direction of the upward and the downward directions). P is the internal pressure of second air chamber74.

For example, consider that air regulator96controls pressure PX to decrease from P1 to P2. Then, as shown inFIG. 5, the state changes from state 1 to state 2, with length L of compression coil spring86changing from L1 to L2, and the internal pressure P of second air chamber74changing from P1 to P2. In this case, if the conditions of state 1 and state 2 are each put into equations (1) to (3), we get the following equations.
FC=k×L1+W−S×P1  (4)
FC=k×L2+W−S×P2  (5)

In a case in which squeegee120stops at a position at which the forces are equal in a state not contacting screen10, force FC becomes zero, so the change in the length L of compression coil spring86, ΔL, is represented by the following equation from equations (4) and (5) above.
ΔL=L2−L1=(P2−P1)S/k(6)

Also, in the above state 1 and state 2, the volume of second air chamber74is decreased by the amount that piston62lowered. The change in the volume of second air chamber74, ΔV1, is represented by the following equation using equation (6) above.
ΔV1=S×ΔL=S2(P2−P1)/k(7)

Thus, for cylinder housing64, during the time that the internal pressure changes from P1 to P2 by air regulator96and until the lowering of squeegee120stops, air corresponding to change amount ΔV1 is removed from second air chamber74.

Also, opening64A (refer toFIG. 3) of a predetermined size connected to air regulator96and second air chamber74is formed in cylinder housing64. Therefore, a specified flow of air per unit of time is supplied to or removed from second air chamber74via opening64A corresponding to the change in internal pressure P. If Q is taken as the flow per unit of time of air through opening64A, response time RT1from when control section148instructs air regulator96to decrease the pressure from pressure P1 to pressure P2 until a value detected by pressure sensor114reaches a target value (pressure P2) is represented by the following equation using equation (7) above.
RT1=ΔV1/Q={S2(P2−P1)/k}/Q(8)

Conversely, as shown inFIG. 6, after squeegee120contacts screen10, the position of squeegee120does not change. Therefore, if, for example, air regulator96changes internal pressure P from pressure P3 to pressure P4, the pressure changes while the volume of second air chamber74remains the same. That is, the change state of second air chamber74is different before and after squeegee120contacts screen10. For cylinder housing64, while the internal pressure is being changed from pressure P3 to pressure P4 by air regulator96, air corresponding to change amount ΔV2 represented by the following equation is removed from second air chamber74.
ΔV2=V3−(P3/P4)V3=V3×(P4−P3)/P4  (9)

In the above equation, V3 is the volume of second air chamber74in a state with squeegee120contacting screen10.

Also, in this case, response time RT2from when control section148instructs air regulator96to decrease the pressure from pressure P3 to pressure P4 until a value detected by pressure sensor114reaches a target value (pressure P4) is represented by the following equation using equation (9) above.
RT2=ΔV2/Q={V3×(P4−P3)/P4}/Q(10)

Further, squeegee120is pressed against screen10with force FC (refer to equation (1)) based on the pressure decrease (decrease in force FB) of second air chamber74.

As above, response time RT1before squeegee contacts screen10is different to response time RT2after squeegee120contacts screen10. With printer100of the present embodiment, change amount ΔV1 is large compared to change amount ΔV2 because the volume of second air chamber74changes a lot as the vertical position of cylinder housing64(squeegee120) changes. Therefore, for response times RT1and RT2that correspond to change amounts ΔV1 and ΔV2, response time RT2is fast compared to response time RT1. Following, control section148of the present embodiment calculates a response time while internal pressure P of second air chamber74decreases, and when detecting that the response time has changed from response time RT1to response time RT2, determines that squeegee120is in a state contacting screen10. When control section148detects contact of squeegee120on screen10, using the set pressure at the point of detection as a reference, control section148further controls internal pressure P to change the pressing force of squeegee120on screen10to a desired degree.

The graph ofFIG. 7shows the relationships between control pressure PX of air regulator96and response times RT1and RT2. The vertical axis is control pressure PX to which control section148controls air regulator96. The horizontal axis is time. In the example shown inFIG. 7, for example, control to decrease pressure in second air chamber74is started from time T1, and squeegee120contacts screen10at time T4. Further, for second air chamber74of housing cylinder64, in the state at time T1 when pressure decreasing started, internal pressure P is 1 MPa (megapascals). Control section148, for example, changes control pressure PX for air regulator96such that the pressure decreases or increases by 0.1 MPa every 60 seconds (S). Also, control section148determines response times RT1and RT2every 60 seconds. This control period of 60 seconds is, for example, enough time for air regulator96to increase or decrease the pressure of second air chamber74by 0.1 MPa, that is, is sufficiently long time compared to response times RT1and RT2.

First, control section148, at time T1, starts control to decrease control pressure PX for air regulator96, that is, to decrease internal pressure P of second air chamber74from 1 MPa to 0.9 MPa. At this stage, because the state is before squeegee120has contacted screen10, at the point when only response time RT1from time T1 has elapsed, the value detected by pressure sensor114reaches 0.9 MPa, and that detection result is entered into control section148. Control section148determines the response time at time T2, which is 60 seconds after time T1. Control section148determines that the response time is response time RT1. Similarly, control section148decreases control pressure PX by 0.1 MPa every 60 seconds.

Subsequently, control section148starts control to decrease control pressure PX from 0.7 MPa to 0.6 MPa at time T3. At time T4, squeegee120contacts screen10. At time T5, which completes the control period at which control pressure PX becomes 0.6 MPa, control section148detects that the response time has changed from response time RT1to response time RT2, and determines that squeegee120has contacted screen10. Note that, strictly speaking, between time T3 and time T4, squeegee120is not contacting screen10, and between time T4 and time T5 squeegee120contacted screen10. Thus, response time RT2measured from time T3 to time T5 is larger compared to response time RT2measured from time T5 by the amount that includes the period in which squeegee120was separated from screen10. In this case, control section148, for example, in a case in which the response time decreased from response time RT1by a predetermined amount, is able to respond by determining that switching to the response time RT2state occurred (squeegee120contacted screen10).

Next, control section148performs control to further decrease control pressure PX in reference to control pressure PX that detected squeegee120contacting screen10, in this case 0.6 MPa, to make the pressing force of squeegee120the desired degree. For example, a pressure decreasing width is set in advance in control section148that indicates how much further to decrease the pressure from control pressure PX at which contact was detected. In the example ofFIG. 7, control section148further decreases control pressure PX at which contact was detected (0.6 MPa) by 0.3 MPa. Control section148decreases control pressure PX to a pressure decreased by 0.3 MPa with respect to 0.6 MPa (in this case, the result being 0.3 MPa). Control section148starts printing work at time T6, which is when control pressure PX becomes 0.3 MPa. Accordingly, printer100enables squeegee120to press against screen10with a desired pressing force, such that suitable printing can be performed.

Also, control section148, similar to control that decreases control pressure PX, is able to detect separation between squeegee120and screen10from changes of response times RT1and RT2during control to increase the pressure. In the example shown inFIG. 7, at time T7, squeegee120separates from screen10. Control section148, for example, in a case in which squeegee120is separated once from screen10to adjust the angle and position of squeegee120, is able to control with reference to control pressure PX at which the response time changed from response time RT2to response time RT1.

Also, there are cases in which response times RT1and RT2are different when control pressure decreases compared to when control pressure increases. This could be a case in which, for example, when squeegee120that has contacted screen10is separated from screen10, solder paste on screen10may have become attached to squeegee120, and by the force due to the viscosity of the solder paste acting (force acting opposite to the separation of squeegee120from screen10), response times RT1and RT2are different for contact and separation. Alternatively, for pressing force adjusting air cylinder56, the friction that arises from the sliding by each other of piston62and cylinder housing64may be different for when piston62is rising to when piston62is lowering. In these cases, it is desirable to measure or simulate response times RT1and RT2in advance and set different values for when squeegee120is lowered and when squeegee120is raised. By this, control section148is able to detect control pressure PX of when squeegee120contacts and separates from screen10more accurately by using different optimal response times RT1and RT2for when squeegee120is raised and when squeegee120is lowered.

The following effects are obtained according to the embodiment described in detail above.

Squeegee120is lowered towards screen10when internal pressure P of second air chamber74of pressing force adjusting air cylinder56is decreased. Control section148performs control of air regulator96based on response times RT1and RT2from starting control of air regulator96to decrease or increase internal pressure P of second air chamber74until a value detected by pressure sensor114reaches a target value of internal pressure P.

With printer100of the present embodiment, response time RT2after squeegee120has contacted screen10is faster compared to response time RT1, which is before contact. Therefore, control section148calculates a response time while internal pressure P of second air chamber74decreases, and when detecting that the response time has changed from response time RT1to response time RT2, determines that squeegee120is in a state contacting screen10. By performing control with reference to this internal pressure P (control pressure PX of air regulator96) for which response times RT1and RT2are detected, it is possible to adjusting the pressing force of squeegee120on screen10. In general, with this type of printer100, pressure sensor114is provided on not only pressing force adjusting air cylinder56, but also an air cylinder that changes the position of a movable section. Thus, according to this printer100, because an existing pressure sensor, pressure sensor114, is used, it is not necessary to separately provide a dedicated sensor (a load sensor or the like) for detecting the pressing force of squeegee120.

Also, with conventional technology, when providing a load sensor on squeegee holding member118or the like in order to accurately measure the load of squeegee120, there is a tendency for the configuration of squeegee unit40to be complex due to the need to provide the load sensor at an appropriate position. Conversely, with printer100of the present embodiment, there is no need to separately provide a load sensor or the like, so the configuration is simple. As described above, according to printer100of the present embodiment, the pressing force of squeegee120is adjusted accurately with a simple configuration, and manufacturing costs are reduced.

Control section148calculates response times RT1and RT2required to decrease or increase control pressure PX of air regulator96by 0.1 MPa. Also, control section148separately detects contact or separation of squeegee120and screen10based on the changes in the measured response times RT1and RT2. Further, when control section148detects contact of squeegee120on screen10, using control pressure PX at the point of detection as a reference, control section148further controls control pressure PX to change the pressing force of squeegee120on screen10to a desired degree.

With printer100, air regulator96that adjusts the pressure of air supplied from air source98is provided between air source98and cylinder housing64. Control section148accurately adjusts internal pressure P of second air chamber74of cylinder housing64by controlling control pressure PX of air regulator96.

Printer100is provided with compression coil spring86that biases squeegee120in a direction against the biasing force due to pressing force adjusting air cylinder56(the downward direction inFIG. 5). According to this configuration, by adjusting the biasing force due to pressing force adjusting air cylinder56and the biasing force due to compression coil spring86, it is possible to change the pressing force of squeegee120.

Also, the biasing force of compression coil spring86acts on squeegee120in addition to the total weight of members that move together with squeegee120(straight line moving member104and the like). Thus, with this configuration, even in a case in which an appropriate pressing force of squeegee is larger than the total weight of the members that move together with squeegee120, screen10is pressed by squeegee120with an appropriate pressing force, and an appropriate amount of solder paste is printed onto printed circuit board20.

Pressing force adjusting air cylinder56is not provided with a seal member at a section at which cylinder housing64and piston62slide by each other. Instead of a seal member, clearance grooves76and78are formed at the sliding portion of pressing force adjusting air cylinder56such that a practically sealed state is maintained. Due to this, variance in resistance due to friction of a seal member that occurs with conventional air cylinders does not occur with pressing force adjusting air cylinder56. Thus, according to pressing force adjusting air cylinder56, the accuracy of control of the pressing force of squeegee120on screen10is improved.

Note that, solder paste printer100is an example of a screen printer. Air cylinders42and56are each an example of a fluid pressure cylinder. Compression coil spring86is an example of an elastic member. Air source98is an example of a fluid supply section. Response times RT1and RT2required to decrease or increase control pressure PX by 0.1 MPa are each an example of a response time. Solder paste is an example of a printing material. Printed circuit board20is an example of a target object. Air is an example of a fluid.

Meanwhile, it goes without saying that the present disclosure is not limited to the above-mentioned embodiment and may be improved and modified in various ways without departing from the scope of the disclosure. For example, in the present embodiment, the configuration for controlling internal pressure P of second air chamber74is one example; it is possible, for example, to provide an electromagnetic direction switching valve that switches to and from supply and removal of air instead of air regulator96, and to control the electromagnetic direction switching valve using control section148. In this case, for example, control section148may time switching of the electromagnetic direction switching valve based on the timing of starting measurement of response times RT1and RT2. Further, instead of being configured to control internal pressure P of second air chamber74, printer100may be configured to control the internal pressure of first air chamber72. Also, squeegee unit40may be configured to lower squeegee120by increasing internal pressure P of second air chamber74.

Also, compression coil spring86is not limited to a quantity of one, multiple thereof may be provided. Further, pressing force adjusting air cylinder56may be provided with a seal member at a section at which cylinder housing64and piston62slide by each other.

Also, in the present embodiment, printer100performs printing by moving squeegee120with respect to a fixed screen10, but screen10may be moved with respect to squeegee120. Also, printer100may perform printing by moving both screen10and squeegee120. Further, the fluid supplied to pressing force adjusting air cylinder56is not limited to air, a gas such as nitrogen or a liquid such as oil may be supplied.

Technical ideas arising from the above described contents are given next. A screen printer according to the present disclosure, wherein the control section, by performing control to bring the squeegee towards the screen, and performing control to separate the squeegee from the screen, uses different of the response times.

According to this printer, the control section, by using different optimal response times for a case in which the squeegee approaches the screen and a case in which the squeegee separates from the screen, is able to more accurately detect the internal pressure of when the squeegee contacts the screen and of when the squeegee separates from the screen.

REFERENCE SIGNS LIST