Liquid supply device

Abstract

This liquid supply device 10 comprises: a pump unit 11 in which multiple pump members are provided; a housing 15 in which multiple drive rods for driving the pump members are integrated; a drive roller 32 which revolves about a central rotation axis in the lateral direction with respect to the direction of reciprocation of the driving rod; a cam member 43 which on one end has a cam surface 48 where the drive roller 32 makes contact and which is rotationally driven by the electric motor 45; a magnet 66 which is provided on the outer periphery of the cam member 43; and a magnetic sensor 71 which outputs a rotation signal in response to magnetic force of the magnet 66.

Description

[Technical Field]

[0001] The present invention relates to a liquid supply device that drives a plurality of pump members to continuously discharge liquid. [Background technology]

[0002] Liquid supply devices are used to apply liquids such as photoresist to the surface of liquid crystal display substrates. Liquid supply devices are classified into piston type, bellows type, tubephragm type, etc. depending on the components incorporated. The piston type has a piston that reciprocates in a cylinder chamber, and the piston expands and contracts a pump chamber separated from the cylinder chamber by the piston. The bellows type has a bellows that expands and contracts housed in a pump block, and the bellows expands and contracts a pump chamber separated from the pump block by the bellows. The tubephragm type has a tubephragm with a pump chamber formed inside, and the pump chamber expands and contracts by supplying and discharging an indirect medium to an outer drive chamber.

[0003] Patent Document 1 describes piston-type and tubephragm-type liquid supply devices. To continuously discharge liquid, the liquid supply device has multiple pump chambers. Multiple rods that expand and contract the respective pump chambers are driven by a single electric motor via a cam member. By using the cam member to shift the discharge timing of each pump, a constant amount of liquid can be continuously discharged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5956920 Summary of the Invention [Problem to be solved by the invention]

[0005] In a liquid supply device, an encoder that monitors the rotation of the output shaft of the electric motor is attached to the casing of the electric motor, allowing detection of pump failures. If the encoder detects the rotation of the output shaft to detect device failures, it will not be possible to detect a failure if the cam member is not rotating at the set rotation speed, even if the electric motor is rotating at a predetermined rotation speed. Furthermore, an encoder has the problem of being expensive if it includes a signal processing circuit from the encoder.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid supply device that can detect, with a simple mechanism, whether a cam member is reliably rotating. [Means for solving the problem]

[0007] The liquid supply device includes a pump unit having a plurality of pump members that each expand and contract a pump chamber, a housing incorporating a plurality of drive rods that drive the plurality of pump members at different timings, a drive roller provided on the drive rod and rotating around a rotation center axis that is horizontal to the reciprocating direction of the drive rod, a cam member having a cam surface that contacts the drive roller provided on its end surface and is driven to rotate around a rotation center axis that is parallel to the reciprocating direction of the drive rod by a rotation drive source, a magnet provided on the outer periphery of the cam member, and a magnetic sensor provided in the housing that is sensitive to the magnetic force of the magnet and outputs a rotation signal. [Effects of the Invention]

[0008] The magnetic force of the magnet attached to the outer periphery of the cam member is detected by a magnetic sensor attached to the housing to detect the rotation of the cam member, so that a stop in rotation of the cam member due to a motor failure or a failure in the transmission of rotation from the motor to the cam member can be reliably detected with a simple, low-cost mechanism. By using a magnet to detect the rotation of the cam member, the durability of the liquid supply device can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a plan view of a liquid supply device according to an embodiment; [Figure 2] FIG. 2 is an enlarged cross-sectional view of the front side of FIG. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the top side of FIG. [Figure 4] FIG. 3(A) is a front view showing the guide cylinder shown in FIG. 2, and FIG. 3(B) is a bottom view of FIG. [Figure 5] FIG. 1A is a plan view of a cam member, and FIG. 1B is a cross-sectional view taken along line AA in FIG. [Figure 6] 3 is a diagram showing the side view of FIG. 2 and the piping of the liquid supply device. FIG. [Figure 7] FIG. 3 is an enlarged cross-sectional view of part B in FIG. 2. [Figure 8] 8 is a cross-sectional view taken along line CC in FIG. 7. [Figure 9] FIG. 4 is an enlarged front view of a portion D in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in Figures 1 to 3, a liquid supply device 10 has a pump unit 11 and a drive unit 12, and the pump unit 11 is attached to the drive unit 12. As shown in Figure 3, the pump unit 11 has a pump block 14 formed with two concave surfaces 13. As shown in Figure 6, the pump block 14 has a rectangular side and is made of resin or metal. The drive unit 12 has a housing 15, and the housing 15 has a connecting portion 15a to which the pump block 14 is attached, a front wall 15b, a rear wall 15c, left and right side walls 15d and 15e, and a bottom wall 15f.

[0011] Resin-made first bellows 16a and second bellows 16b serving as pump members are disposed within the respective concave surfaces 13. Each bellows 16a, 16b has the same structure, and the members for driving each are given the same reference numerals. Each bellows 16a, 16b has a head portion 17, an annular base portion 18, and a bellows portion 19 integrally provided between the head portion 17 and the annular base portion 18. A pump chamber 20 is formed between each bellows 16a, 16b and the concave surface 13, and each pump chamber 20 expands and contracts due to the expansion and contraction of the bellows 16a, 16b.

[0012] A cylindrical spring receiving cylinder 21 is disposed inside each of the bellows 16a, 16b, and a flange 22 of the spring receiving cylinder 21 and the annular base portion 18 of the bellows 16a, 16b are sandwiched between the pump block 14 and the housing 15. A plunger 23 is disposed inside the spring receiving cylinder 21, and the tip end of the plunger 23 is threadedly connected to the head portion 17, and the base end of the plunger 23 protrudes into a through-hole 24 formed in the housing 15. A spring receiving member 25 is provided at the base end of the plunger 23. The spring receiving member 25 may be integral with the plunger 23, or the plunger 23 and the spring receiving member 25 may be separate members.

[0013] A compression coil spring 27 is disposed outside the plunger 23, with one end of the compression coil spring 27 abutting against a step portion of the spring receiving cylindrical body 21 and the other end abutting against the spring receiving member 25. A spring force is applied to the plunger 23 by the compression coil spring 27 in a downward direction in FIG. 3. A spring force is applied to the bellows 16a, 16b via the plunger 23 in a direction that moves the head portion 17 toward the annular base portion 18 and contracts the bellows portion 19 in the axial direction. When the bellows 16a, 16b contract, the pump chamber 20 expands.

[0014] The plunger 23 is pressed by the spring force of a compression coil spring 27 against a drive rod 28 that is reciprocable in the axial direction indicated by the symbol P in FIG. 3 , and each drive rod 28 has the same structure. A cover portion 29 that covers the base end of the plunger 23 is provided at the upper end of the drive rod 28. A roller housing portion 31 is provided at the lower end of the drive rod 28, and a drive roller 32 is disposed in the roller housing portion 31. A support shaft 33 is provided on the drive rod 28 in a direction perpendicular to the reciprocating direction P of the drive rod 28, which is horizontal, and the drive roller 32 is attached to the support shaft 33. As a result, the drive roller 32 rotates about a rotation center axis R that is horizontal to the reciprocating direction of the axial direction P of the drive rod 28. The rotation center axes R are coaxial.

[0015] A guide cylinder 34 is attached to the through hole 24. As shown in FIG. 4, the guide cylinder 34 has a fitting portion 35 that fits into the through hole 24 and a guide portion 36 that guides the drive rod 28. Guide rollers 37 are provided on both ends of the support shaft 33, and the guide cylinder 34 is provided with a guide groove 38 that guides the guide rollers 37. The guide groove 38 contacts the guide rollers 37 and guides the movement of the guide rollers 37 in the vertical direction in FIGS. 2 and 3. Four slits 39 extending axially from the lower end surface of the guide portion 36 are formed in the lower end of the guide portion 36, and mounting holes 41 are formed in the guide portion 36 that pass between the bottom surface of each slit 39 and the upper surface of the guide portion 36. The guide cylinder 34 is fixed to the housing 15 by bolts 42 attached to the respective mounting holes 41.

[0016] A cam member 43 is provided in the housing 15 so as to be rotatable about a central axis of rotation O that is parallel to the reciprocating direction P of the drive rod 28, and the cam member 43 is supported on the bottom wall 15f of the housing 15 via a thrust bearing 44. An electric motor 45 serving as a rotational drive source is attached to the bottom wall 15f, and an output shaft 46 of the electric motor 45 is attached to the cam member 43, so that the cam member 43 is rotated by the electric motor 45. The cam member 43 is accommodated in a drive chamber 47 formed between the connecting portion 15a of the housing 15 and the bottom wall 15f.

[0017] Fig. 5(A) is a plan view of cam member 43, and Fig. 5(B) is a cross-sectional view taken along line AA in Fig. 5(A). Cam member 43 is an end cam having an annular cam surface 48 formed on the outer periphery of the end face of a disk-shaped member. Cam surface 48 has a protruding surface 49 that protrudes toward pump unit 11, a receding surface 50 that is positioned receding from protruding surface 49 and shifted 180 degrees in the rotation direction S of cam member 43, and an inclined surface 51 therebetween. In Fig. 2, protruding surface 49 is shown on the right side of cam member 43, and receding surface 50 is shown on the left side of cam member 43. In Fig. 3, protruding surface 49 is shown in the center of cam member 43 without showing the entire cam member 43 in cross section.

[0018] The two drive rollers 32 are offset by 180 degrees relative to the cam member 43 in the rotational direction of the cam member 43, and when one drive roller 32 contacts the protruding surface 49, the other drive roller 32 contacts the retracting surface 50. For example, when the drive roller 32 attached to one drive rod 28 for driving the first bellows 16a contacts the protruding surface 49, the one drive rod 28 reaches its uppermost position in Figures 2 and 3. As a result, the head portion 17 of the bellows 16a reaches its uppermost position, and the bellows portion 19 is extended, i.e., expanded, and the pump chamber 20 is contracted by the bellows 16a.

[0019] At this time, the drive roller 32 attached to the other drive rod 28 for driving the second bellows 16b contacts the retraction surface 50 due to spring force. As a result, the other drive rod 28 is in the retracted end position, the head portion 17 of the bellows 16b is in the retracted end position, and the bellows portion 19 is in a contracted state. When the bellows portion 19 is in a contracted state, the pump chamber 20 is expanded by the bellows 16b. In this way, the two bellows 16a, 16b alternately expand and contract as the cam member 43 rotates, and are driven at different timings. As a result, the two pump chambers 20 alternately expand and contract.

[0020] As shown in Figure 5(B), if the axial length of the portion of the cam member 43 where the protruding surface 49 is formed is L1 and the axial length of the portion where the receding surface 50 is formed is L2, the portion where the protruding surface 49 is formed is the portion with the longest axial length compared to the other portions.

[0021] Lubricating oil is applied to the rotating members in the drive chamber 47, such as the drive roller 32 and guide roller 37, and to members that come into contact with the rotating members. To prevent the lubricating oil in the drive chamber 47 from leaking toward the plunger 23 or pump block 14, a seal member 52 is installed between the guide cylinder 34 and the drive rod 28, and a seal member 53 is installed between the guide cylinder 34 and the housing 15.

[0022] As shown in FIG. 6 , suction ports 54 are formed in the bottom surface of the pump block 14 and communicate with each pump chamber 20, and discharge ports 55 are formed in the top surface of the pump block 14. A suction-side pipe 57 is connected to a liquid tank 56 into which liquid has been poured, and branches 57a and 57b of the suction-side pipe 57 are connected to the suction port 54. A discharge-side pipe 59 is connected to a discharge member 58, and branches 59a and 59b of the discharge-side pipe 59 are connected to the discharge port 55. Check valves 61 are provided in each of the branches 57a and 57b. The check valves 61 operate to supply liquid from the liquid tank 56 to the pump chamber 20 via the suction-side pipe 57 and to prevent backflow of the liquid. Furthermore, check valves 62 are provided in each of the branches 59a and 59b. The check valves 61 operate to discharge liquid from the pump chamber 20 to the discharge member 58 via the discharge-side pipe 59 and to prevent backflow of the liquid. 1 to 3, the suction side pipe 57, the discharge side pipe 59, etc. shown in FIG. 6 are omitted.

[0023] To drive the liquid supply device 10 and discharge liquid from the liquid tank 56 to the discharge member 58, the electric motor 45 is driven to rotate the output shaft 46. Rotating the output shaft 46 rotates the cam member 43 about the central axis of rotation O, and the drive roller 32 in contact with the cam surface 48 drives the two bellows 16a, 16b at different times via the plunger 23. That is, when one bellows 16a expands to discharge liquid from one pump chamber 20 to the discharge member 58, the other bellows 16b contracts to inject liquid from the liquid tank 56 into the other pump chamber 20. At this time, the contraction of the bellows 16b is performed by the spring force of the compression coil spring 27. As a result, liquid is continuously discharged from the liquid supply device 10 to the discharge member 58 at a constant rate. The position of the suction port 54 does not have to be on the bottom surface of the pump block 14. Similarly, the position of the discharge port 55 does not have to be on the top surface.

[0024] 5(B), the axial length of the portion of cam surface 48 where protruding surface 49 is formed is L1, and this portion is the portion of cam member 43 with the longest axial length, i.e., thick portion 63. The portion where receding surface 50 is formed, which is positioned 180 degrees offset in the rotational direction from thick portion 63, has an axial length of L2 and is thin portion 64.

[0025] 7 is an enlarged cross-sectional view of part B in FIG. 2, FIG. 8 is a cross-sectional view taken along line CC in FIG. 7, and FIG. 9 is an enlarged cross-sectional view of part D in FIG.

[0026] As shown in FIGS. 7 to 9, a magnet accommodating hole 65 is formed in the outer periphery of cam member 43, and magnet accommodating hole 65 opens to the outer periphery of cam member 43. Magnet accommodating hole 65 is formed in thick-walled portion 63, which is the portion of the outer periphery of cam member 43 that has the longest axial length. A magnet 66 is disposed in magnet accommodating hole 65, and is covered by a magnet holder 67 made of resin, which is a non-magnetic material. Magnet 66 is cylindrical, and the upper and lower end faces in FIG. 7 have opposite polarities. Magnet 66 is positioned toward the outer periphery of cam member 43, and the thickness of the magnet holder 67 on the outer periphery side of cam member 43 is set thin. Magnet holder 67 is engaged with cam member 43 by claws 68 formed on the outer periphery to prevent it from coming off, and a pin 69 attached to cam member 43 prevents magnet holder 67 from rotating.

[0027] Magnet 66 is provided in the portion of cam member 43 that has the longest axial length L1, i.e., thick portion 63. In this way, magnet 66 is disposed in thick portion 63 that is used to form protruding surface 49, so magnet 66 can be incorporated into cam member 43 without increasing the axial dimension of cam member 43. However, in Figure 5(B), the magnet is not shown in thick portion 63 where protruding surface 49 is formed.

[0028] A magnetic sensor 71 is provided on the front wall 15b of the housing 15. As shown in FIGS. 2 and 7, the magnetic sensor 71 is incorporated into an accommodating groove 72 formed in the front wall 15b corresponding to the position of the magnet 66. Therefore, when the cam member 43 rotates, the magnetic field of the magnet 66 passes through the magnet holder 67 and is applied to the magnetic sensor 71 with each rotation, and the magnetic sensor 71 outputs a rotation signal in response to the magnetic force of the magnet 66. The output signal from the magnetic sensor 71 is output to a control unit (not shown), which determines whether the cam member 43 is rotating and, if so, calculates the number of rotations of the cam member 43 per unit time.

[0029] If the magnet holder 67 is not present and the cam member 43 is made of a magnetic material, the magnetic field of the magnet 66 cannot be detected by the magnetic sensor 71. If the magnet 66 is covered with a non-magnetic magnet holder 67 and placed in the magnet accommodating hole 65, the cam member 43 can be made of a magnetic material.

[0030] As shown in FIGS. 1 and 8, an observation window 73 is provided in the housing 15. The observation window 73 is provided in the front wall 15b adjacent to the magnetic sensor 71 and is positioned vertically in FIG. 1 to correspond to the magnetic sensor 71, allowing the portion of the cam member 43 where the magnet 66 is provided to be visible from outside the housing 15. This allows an operator to observe the rotation of the cam member 43 from outside the liquid supply device 10. Visibility is improved by coloring either or both of the magnet holder 67 and the magnet 66 a different color from the cam member 43. A transparent cover member 74 is attached to the observation window 73 to prevent foreign matter from entering the drive chamber 47 from the outside. In FIG. 8, the position of the magnet 66 at the observation window 73 is indicated by a two-dot chain line.

[0031] Lubricating oil is applied to the sliding and rotating parts inside drive chamber 47, making it impossible to detect the rotation of the cam member by an optical sensor. In contrast, a magnetic sensor 71 that responds to the magnetic force of magnet 66 is used to detect the rotation of cam member 43 and output shaft 46 of electric motor 45, so the rotation of cam member 43 can be reliably detected.

[0032] The present invention is not limited to the above-described embodiment and can be modified in various ways without departing from the spirit and scope of the present invention. For example, while the liquid supply device 10 described above includes two bellows 16a, 16b as pump members, the number of pump members is not limited to two, and may be three or more. The pump members are not limited to the above-described bellows, but may also be pistons or tube phragms. Furthermore, the magnet accommodating hole 65 may be provided in a portion other than the thick portion of the cam member 43. Furthermore, the rotational drive source is not limited to an electric motor, and an air motor may also be used. Furthermore, the electric motor may be a stepping motor, a servo motor, or an induction motor. [Industrial Applicability]

[0033] The liquid supplying device is used to supply a liquid to an object to be coated, for example, when coating a liquid such as a photoresist liquid on the surface of a liquid crystal display substrate.

Claims

1. a pump unit provided with a plurality of pump members each of which expands and contracts a pump chamber; a housing incorporating a plurality of drive rods for driving the plurality of pump members at different timings; a drive roller provided on the drive rod and rotating around a rotation center axis that is lateral to the reciprocating direction of the drive rod; a cam member having a cam surface on its end surface that comes into contact with the drive roller, the cam member being rotated by a rotary drive source around a rotation center axis that is parallel to the reciprocating direction of the drive rod; a magnet provided on the outer periphery of the cam member; a magnetic sensor provided in the housing, the magnetic sensor sensing the magnetic force of the magnet and outputting a rotation signal; A liquid supply device having:

2. 2. The liquid supply device according to claim 1, The liquid supply device further comprises an observation window provided in the housing through which the outer periphery of the cam member on which the magnet is provided can be viewed from outside the housing.

3. 3. The liquid supply device according to claim 1, the cam member is made of a magnetic material, The liquid supply device has a magnet holder made of a non-magnetic material that covers the magnet, and the magnetic field generated by the magnet passes through the magnet holder and is applied to the magnetic sensor.

4. The liquid supply device according to any one of claims 1 to 3, the housing has two of the drive rods, and the drive rollers provided on the respective drive rods have the same rotational center axis; the cam surface has a protruding surface that protrudes toward the housing, a receding surface that is offset from the protruding surface by 180 degrees in the rotational direction and is positioned receding from the protruding surface, and an inclined surface between the protruding surface and the receding surface, A liquid supply device, wherein the magnet is disposed on the thick portion of the cam member where the protruding surface is provided.

5. The liquid supply device according to any one of claims 1 to 4, A liquid supply device in which the pump member is a bellows that forms the pump chamber between itself and a concave surface formed in the housing, and the bellows has an annular base that is sandwiched between the pump unit and the housing, a head that has the drive rod attached thereto and moves back and forth, and a bellows portion between the annular base and the head.

6. The liquid supply device according to any one of claims 1 to 5, a guide cylinder for guiding the drive rod in a reciprocating manner is attached to the housing; guide rollers are provided on both ends of the support shaft on which the drive roller is provided; The liquid supply device further comprises a guide groove provided in the guide cylinder for guiding the guide roller.

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