Patent Application
20150219092
1. Technical Field
The present invention relates to a liquid transport method and a liquid transport apparatus.
2. Related Art
A micro pump disclosed in JP-A-2013-24185 is known as a liquid transport apparatus configured to transport liquid. The micro pump includes a plurality of fingers arranged along a tube, and a cam presses the fingers in sequence, so that the tube is collapsed and hence liquid is transported. An encoder for measuring a rotational angle of the cam is provided.
In a liquid transport using the cam and the fingers, liquid feeding properties include periodicity. Although a signal output from the encoder has periodicity, a position of a reference point of an output signal (hereinafter, referred to as “signal original point”) in one cycle differs from one machine to another. Therefore, it is required to obtain a relationship between the signal original point and a rotational angle as a reference of the cam (hereinafter, referred to as “pump original point”) in advance in order to control the liquid transport.
In terms of this point, the relationship between the signal original point and the pump original point may be obtained by detecting an amount of transportation by actually transporting the liquid. However, since the amount of transportation is small, detection of the amount of transportation requires high degree of accuracy, so that this method is not suitable for mass production.
An advantage of some aspects of the invention is to obtain a relationship between a signal original point and a pump original point easily.
An aspect of the invention provides a liquid transport method for a liquid transport apparatus, including: rotating a cam from a reference position of rotation of the cam rotating for transporting liquid; determining whether or not the cam rotates to a predetermined rotational angle on the basis of an image of the liquid transport apparatus captured when the cam is rotated and stopped; and memorizing a signal value indicating a rotational angle of the cam from the reference position of rotation until the cam rotates to the predetermined rotational angle.
Other characteristics of the aspects of the invention will be apparent from the specification and attached drawings.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
According to the specification and the attached drawings, at least the followings become apparent.
An aspect of the invention provides a liquid transport method for a liquid transport apparatus including: rotating a cam from a reference position of rotation of the cam rotating for transporting liquid; determining whether or not the cam rotates to a predetermined rotational angle on the basis of an image of the liquid transport apparatus captured when the cam is rotated and stopped; and memorizing a signal value indicating a rotational angle of the cam from the reference position of rotation until the cam rotates to the predetermined rotational angle.
A liquid transport method using a tube; a cam; a finger arranged between the tube and the cam; a drive unit configured to rotate the cam; an encoder configured to output a rotational angle of the cam; and an image pickup unit configured to capture an image of the cam, and includes obtaining a reference point of a signal output from the encoder; rotating the cam from the reference point of the signal; determining that the cam reaches a predetermined rotational angle on the basis of an image captured by the image pickup unit when the cam is rotated and stopped; and memorizing a counted value of an output signal of the encoder until the cam reaches the predetermined rotational angle from the reference point of the signal.
With the liquid transport method as described above, the relationship between the signal original point and the pump original point may be obtained easily.
A position detection mark provided on the cam may be detected from the image to detect the rotational angle of the cam. By providing the position detection mark on the cam, the rotational angle of the cam can be detected easily from the captured image, so that the relationship between the signal original point and the pump original point can be obtained easily.
The rotational angle of the cam may be detected by detecting an edge of the position detection mark to detect the rotational angle of the cam. Since the position detection mark and the rotational angle of the cam correspond to each other, whether the cam reaches the rotational angle corresponding to the pump original point can be obtained easily by detecting the edge of the mark.
A position of a pressing member configured to press a member which defines a flow channel of the liquid may be detected in association with the rotation of the cam from the image to detect the rotational angle of the cam.
A position of the finger may be detected from the image to detect the rotational angle of the cam. Since the positions of the fingers correspond to the rotational angle of the cam, the rotational angle of the cam is detected by detecting the positions of the fingers, and hence the relationship between the signal original point and the pump original point may be obtained easily.
The rotational angle of the cam when the reversely flowed liquid returns by an amount corresponding to the reverse flow may be used as a reference of the predetermined angle. Accordingly, control of a constant amount transportation of liquid is facilitated.
A liquid transport apparatus includes: a cam configured to rotate for transporting liquid, and a control unit configured to read a memorized signal value indicating a rotational angle of the cam rotating from a reference position of rotation to a predetermined rotational angle, determine whether or not the cam rotates from the reference position to the predetermined rotational angle, and rotate the cam to a desired rotational angle with reference to a position where the cam is determined to have rotated to the predetermined rotational angle.
With the liquid transport apparatus as described above, the relationship between the signal original point and the pump original point may be obtained easily.
A rotational position measuring apparatus configured to measure a rotational position of a cam in a liquid transport apparatus including the cam configured to rotate to transport liquid, and an encoder configured to output a rotational angle of the cam, includes: a cam rotating unit configured to rotate the cam from a reference position of rotation of the cam; a determining unit configured to determine whether or not the cam rotates to a predetermined rotational angle on the basis of an image of the liquid transport apparatus captured when the cam is rotated and stopped; and a setting unit configured to memorize a counted value of the encoder during the rotation of the cam from the reference position of rotation to the predetermined rotational angle in the liquid transport apparatus.
A rotational position measuring apparatus provided with a liquid transport apparatus having a tube; a cam; a finger arranged between the tube and the cam; a drive unit configured to rotate the cam; and an encoder configured to output a rotational angle of the cam, and an image pickup unit configured to capture an image of the liquid transport apparatus, and configured to measure a rotational position of the cam, includes a reference point searching unit configured to obtain a reference point of a signal from the encoder; a cam rotating unit configured to rotate the cam from the reference point of the signal from the encoder; a determining unit configured to determine that the cam reaches a predetermined rotational angle on the basis of an image captured by the image pickup unit when the cam is rotated and stopped; and a memory unit configured to memorize a counted value of the encoder until the cam reaches the predetermined rotational angle from the reference point of the signal.
With the rotational position measuring apparatus as described above, the relationship between the signal original point and the pump original point may be obtained easily.
The liquid transport apparatus 1 is an apparatus configured to transport liquid. The liquid transport apparatus 1 includes a main body 10, a cartridge 20, and a patch 30. The main body 10, the cartridge 20, and the patch 30 are separable as illustrated in
The pump unit 5 has a function as a pump for transporting liquid stored in the cartridge 20, and includes a tube 21, a plurality of fingers 22, a cam 11, and a drive mechanism 12.
The tube 21 is a tube for transporting liquid. An upstream side of the tube 21 (the upstream side with reference to a direction of transport of the liquid) communicates with a storage portion of the liquid in the cartridge 20. The tube 21 has a resiliency to an extent to close when pressed by the fingers 22 and restore when a force from the fingers 22 is released. The tube 21 is arranged in a partially arcuate shape along an inner surface of a tube guide wall 25 of the cartridge 20. The arcuate portion of the tube 21 is arranged between the inner surface of the tube guide wall 25 and the plurality of fingers 22. A center of the arc of the tube 21 matches a center of rotation of the cam 11.
The fingers 22 are members for closing the tube 21. The fingers 22 operate upon reception of a force from the cam 11. The fingers 22 each include a rod-shaped shaft portion and a flange-shaped pressing portion and is formed into a T-shape. The rod-shaped shaft portion comes into contact with the cam 11, and the flange-shaped pressing portion comes into contact with the tube 21. The fingers 22 are supported so as to be movable along an axial direction.
The plurality of fingers 22 are arranged radially from the center of rotation of the cam 11 at regular distance. The plurality of fingers 22 are arranged between the cam 11 and the tube 21. Here seven fingers 22 are provided. In the following description, fingers may be referred to as a first finger 22A, a second finger 22B, . . . , and a seventh finger 22G from the upstream side of the direction of transport of the liquid.
The cam 11 has projecting portions 11A at four positions on an outer periphery thereof. The plurality of fingers 22 are arranged on the outer periphery of the cam 11, and the tube 21 is arranged on the outside of the fingers 22. The fingers 22 are pressed by the projecting portions 11A of the cam 11, so that the tube 21 is closed. When the fingers 22 come out of contact with the projecting portions 11A, the tube 21 is restored to the original shape by resiliency of the tube 21. When the cam 11 rotates, the seven fingers 22 are pressed in sequence by the projecting portions 11A, and close the tube 21 in sequence from the upstream side in the direction of transport. Accordingly, when the tube 21 is caused to perform a peristaltic action, and liquid is compressed and transported to the tube 21.
The drive mechanism 12 is a mechanism configured to drive the cam 11 to rotate and, as illustrated in
The piezoelectric actuator 121 is an actuator for rotating the rotor 122 by using vibrations of a piezoelectric element. The piezoelectric actuator 121 vibrates a vibrator by applying a drive signal on the piezoelectric elements adhered to both surfaces of the rectangular vibrator. An end portion of the vibrator comes into contact with the rotor 122, and when the vibrator vibrates, the end portion vibrates while tracing out a predetermined orbit such as an oval orbit or a figure eight orbit. By the end portion of the vibrator coming into contact with the rotor 122 at a portion of the vibration orbit, the rotor 122 is driven to rotate. The piezoelectric actuator 121 is biased toward the rotor 122 by a pair of springs so that the end portion of the vibrator comes into contact with the rotor 122.
The rotor 122 is a driven member rotated by the piezoelectric actuator 121. The rotor 122 is provided with a rotor pinion which constitutes part of the deceleration transmitting mechanism 123.
The deceleration transmitting mechanism 123 is a mechanism configured to transmit a rotation of the rotor 122 to the cam 11 at a predetermined gear ratio. The deceleration transmitting mechanism 123 includes the rotor pinion, a transmitting wheel 123A, and a cam gear (see
The pump unit 5 includes the tube 21, the plurality of fingers 22, the cam 11 and the drive mechanism 12, and the cam 11 and the drive mechanism 12 are provided on the main body 10, and the tube 21 and the plurality of fingers 22 are provided on the cartridge 20. The main body 10 is provided with a measuring unit 40 configured to measure the rotational angle of the cam 11 or the like, a control unit 50 configured to control the piezoelectric actuator 121 or the like, and a battery 19 configured to supply power to the piezoelectric actuator 121 or the like.
The measuring unit 40 includes a cam side measuring unit 41 for measuring the rotational angle of the cam 11, and first and second measuring units 42 and 43 configured to measure first and second rotational angles of the rotor 122.
The cam side measuring unit 41 is a rotary-type encoder including a light-emitting portion 41A and a light-receiving portion 41B. The cam gear is provided with a cam-side reflecting portion 111 formed thereon, and the cam-side reflecting portion 111 reflects light from the light-emitting portion 41A and the light-receiving portion 41B receives the reflected light. The light-receiving portion 41B outputs an output signal CAM_Z in accordance with an amount of received light to the control unit 50.
The first and second measuring units 42 and 43 are also rotary-type encoders provided with light-emitting portions 42A and 43A and light-receiving portions 42B and 43B. The rotor 122 is provided with first and second reflecting portions 124 and 125 formed thereon. The first reflecting portions 124 reflect light from the light-emitting portion 42A of the first measuring unit 42 and the light-receiving portion 42B of the first measuring unit 42 receives the reflected light. The second reflecting portion 125 reflects light from the light-emitting portion 43A of the second measuring unit 43, and the light-receiving portion 43B of the second measuring unit 43 receives the reflected light. The light-receiving portions 42B and 43B of the first and second measuring units 42 and 43 output output signals ROT_A and ROT_Z in accordance with the amount of received light to the control unit 50, respectively.
The cam side measuring unit 41 and the first and second measuring units 42 and 43 are not limited to a reflective optical sensor, but may be a transmissive optical sensor.
The control unit 50 includes a counter 51, a memory unit 52, an operating unit 53, and a driver 54. The counter 51 counts the number of edges included in the output signal ROT_A from the first measuring unit 42. The counted value of the counter 51 indicates the rotational angle of the rotor 122. Since the rotational angle of the rotor 122 and the rotational angle of the cam 11 correspond to each other, the counted value of the counter 51 indicates also the rotational angle of the cam 11. The memory unit 52 memorizes a program used by the operating unit 53 for driving the driver 54, and memorizes a position on the output signal ROT_A corresponding to the pump original point. The operating unit 53 executes the program memorized in the memory unit 52, and drives the driver 54 on the basis of the counted value of the counter 51 (the rotational angles of the cam 11 and the rotor 122) and the position on the signal ROT_A corresponding to the pump original point. The driver 54 outputs a drive signal to the piezoelectric actuator 121 of the drive mechanism 12 in accordance with an instruction from the operating unit 53.
As described later, the control unit 50 corresponds to a determining unit configured to determine a reference of the output signal ROT_A on the basis of the signal ROT_Z output after an output of the signal CAM_Z. The control unit 50 corresponds to a reference point searching unit configured to obtain a reference point of the signal ROT_A.
Here, while the cam 11 rotates from 0 degree to 60 degrees (hereinafter, referred to as “transportation period”), the amount of transportation is substantially proportional to the rotational angle. In this transportation period, the liquid is transported by closing the tube 21 from the first finger 22A in sequence. While the cam 11 rotates from 60 degree to 80 degrees (hereinafter, referred to as “steady period”), the accumulated amount of transportation does not change. In this steady period, the seventh finger 22G continuously closes the tube 21. While the cam 11 rotates from 80 degree to 85 degrees (hereinafter, referred to as “reverse flow period”), the accumulated amount of transportation decreases. In other words, liquid flows reversely in the reverse flow period.
By the rotation of the cam 11 as illustrated in
While the cam 11 rotates from 85 degree to 90 degrees (hereinafter, referred to as “restoration period”), liquid of an amount corresponding to a reverse flow is transported. In other words, the reference position and 0 degree correspond to the position of the cam 11 after the restoration period.
In this manner, when the cam 11 is rotated, there are a period in which liquid of an amount corresponding to the amount of rotation is transported, a period in which the liquid is not transported, and a period in which the liquid flows reversely. As a result, as illustrated in
From the viewpoint of transportation of liquid with high degree of accuracy, the accumulated amount of transportation of the liquid is preferably linear with respect to time. In order to do so, for example, the cam 11 needs to be adjusted to rotate faster in the reverse flow period and the restoration period than in the steady period. In order to do so, the counted value of the counter 51, that is, the rotational angle of the cam 11 and the amount of transportation of the liquid need to be coordinated accurately.
As described above, the first measuring unit 42 outputs the signal ROT_A in accordance with the amount of the reflected light received by the light-receiving portion 42B. Here, as illustrated in
The second measuring unit 43 outputs the signal ROT_Z in accordance with the amount of the reflected light received by the light-receiving portion 43B. Here, the rotor 122 is provided with one second reflecting portion 125. Therefore, the second measuring unit 43 outputs the signal ROT_Z including one pulsed waveform every time when the rotor 122 rotates by one turn.
As described above, the cam-side measuring unit 41 outputs the signal CAM_Z in accordance with the amount of the reflected light received by the light-receiving portion 41B. The cam 11 is provided with one cam-side reflecting portion 111 formed thereon and the cam-side measuring unit 41 outputs the signal CAM_Z including one pulsed waveform every time when the cam 11 rotates by one turn.
Here, since the rotor 122 rotates by 40 turns while the cam 11 rotates by one turn, the number of pulses included in the output signal ROT_A of the first measuring unit 42 corresponding to the rotor 122 in one cycle of the output signal CAM_Z of the cam side measuring unit 41 is 40×12=480. If a leading edge and a fall edge of pulses of the signal ROT_A are determined to be one count respectively, 960 counts from 0 to 959 are measured every time when the cam 11 rotates by one turn as illustrated in
In order to coordinate the signal ROT_A to the cycle of the signal CAM_Z accurately for measuring the rotational angle of the cam 11 accurately, the edge included in the signal CAM_Z is ideally steep, for example, as illustrated in
First of all, in Step S11, the control unit 50 detects a leading edge of the pulsed waveform of the signal CAM_Z. Subsequently, in Step S12, the control unit 50 detects an edge of the signal ROT_Z appearing immediately after the detection of the edge of the signal CAM_Z as indicated by an arrow from the signal CAM_Z to the signal ROT_Z in
After the determination of the signal original point, a process of determining the pump original point is performed. It is because the signal original point does not match the pump original point which is to be determined from the view point of control in constant amount liquid feeding since the signal original point is determined from reproducibility point of view.
Here, the position where the reversely flowed liquid returns by an amount corresponding to the reverse flow, that is, the reference position of the cam 11 in
The rotational angle of the cam 11 corresponding to the pump original point may be obtained easily by image processing. Here, for the sake of convenience of description, a solid line with an arrow extending from a rotating shaft of the cam 11 in the radial direction is determined as the pump original point as illustrated in
The cam 11 is aligned with the rotational angle corresponding to the signal original point, and the pump original point determination process is started.
In Step S21, the cam 11 is rotated by an angle corresponding to one count of the signal ROT_A. In other words, the cam 11 is rotated by a cam rotating unit provided on a manufacture line, for example, so that a value Z counted from the signal original point increments by one in the signal ROT_A. The value Z increments by one every time when Step S21 is executed.
Subsequently, an image of the cam 11 is captured in Step S22. Capturing of the image is performed by using a camera (image-pickup unit) provided in the manufacture line, for example.
In Step S23, the rotational angle of the cam 11 is detected by analyzing the captured image. Specifically, in the first embodiment, the positions of the projecting portions 11A are detected by detecting edges of the projecting portions 11A of the cam 11 from the captured image. Here, the reason why the edges of the projecting portions 11A of the cam 11 are detected is because displacement of the projecting portions 11A of the cam 11 is significantly larger than the rotation by an angle corresponding to one count of the signal ROT_A because the projecting portions 11A are apart from the rotating shaft of the cam 11, so that a minute change in rotational angle of the cam 11 appears in a change of the projecting portions 11A of the cam 11. In other words, accuracy of edge detection may be improved.
Subsequently, in Step S24, whether or not the rotational angle of the cam 11 reaches the pump original point is determined. If the cam 11 is determined to have reached the pump original point, the procedure goes to the next Step S25, and if the rotational angle of the cam 11 is determined not to have reached the pump original point, the procedure goes back to Step S21. In Step S25, the counted value Z is memorized in the memory unit 52 of the control unit 50, and a series of process is terminated.
In this manner, the position on the signal ROT_A corresponding to the pump original point is determined to an edge behind the signal original point by the value Z.
After the pump original point determination process, the control unit 50 performs the transportation of the liquid as described below. First of all, the control unit 50 drives the piezoelectric actuator 121, rotates the rotor 122 and the cam 11, and detects the edge of the signal CAM_Z. On the basis of the edge of the signal ROT_Z detected immediately after the edge of the signal CAM_Z is detected, the control unit 50 detects an edge of the signal ROT_A (signal original point) detected immediately thereafter. The control unit 50 counts the edges of the signal ROT_A after the detection of the signal original point, and further rotates the rotor 122 and the cam 11 until the counted number of edges reaches the number of edges Z memorized in the memory unit 52. When the counted number of edges reaches the value Z, the cam 11 is located at a rotational angle corresponding to the pump original point. Accordingly, as illustrated in
As described above, in the first embodiment, on the basis of the edge of the signal ROT_Z detected immediately after the edge of the signal CAM_Z is detected, the edge of the signal ROT_A detected immediately thereafter is determined as the signal original point (reference point) of the signal ROT_A. Then, the cam 11 is rotated by an amount corresponding to one count from the signal original point of the signal ROT_A, and then is stopped, and the image of the cam 11 is captured. From the positions of the projecting portions 11A of the cam 11 obtained by analyzing the image captured as described above, the fact that the cam 11 reaches the pump original point is determined. Subsequently, the counted value Z from the signal original point of the signal ROT_A until the cam 11 reaches the pump original point is memorized in the memory unit 52. Therefore, since the position to which the cam 11 is rotated from the signal original point of the signal ROT_A by the counted value Z is determined as the pump original point, the relationship between the signal original point and the pump original point can be obtained easily.
In the second embodiment, a method of detecting the rotational angle of the cam 11 in Step S23 of the pump original point determination process is changed. In other words, the projecting portions 11A of the cam 11 each are provided with a position detection mark M1 such as a thin line or cross lines as illustrated in
As described above, in the second embodiment, the position detection marks M1 are marked on the projecting portions 11A of the cam 11, and the fact that the cam 11 reaches the pump original point is determined from the positional relationship of the marks M1 obtained by analyzing the captured image of the cam 11. Since the position to which the cam 11 is rotated from the signal original point of the signal ROT_A by the counted value Z is determined as the pump original point, the relationship between the signal original point and the pump original point can be obtained easily.
In the third embodiment as well, a method of detecting the rotational angle of the cam 11 in Step S23 of the pump original point determination process is changed. In other words, positions of the fingers 22 are detected by image analysis, and the rotational angle of the cam 11 may be determined on the basis of the result of detection. As a method of detecting the positions of the fingers 22, for example, the edges of the fingers 22 are detected by using the image captured in Step S22 for example, and the rotational angle of the cam 11 may be determined from the detected positions of the fingers 22. For example, in a manner that the cam 11 reaches the reference position in
Alternatively, position detection marks M2 may be marked on the fingers 22 in advance as illustrated in
As described above, in the third embodiment, the fact that the cam 11 reaches the pump original point is determined from the positional relationship of the fingers 22 obtained by analyzing the captured image of the cam 11. Since the position to which the cam 11 is rotated from the signal original point of the signal ROT_A by the counted value Z is determined as the pump original point, the relationship between the signal original point and the pump original point can be obtained easily.
The embodiments described above are for facilitating the understanding of the invention, and are not for interpreting the invention in a limited range. It is needless to say that the invention may be modified or improved without departing the scope of the invention and equivalents are included in the invention. For example, the pump original point may be obtained by combining the first embodiment and the third embodiment.
The entire disclosure of Japanese Patent Application No. 2014-16650, filed Jan. 31, 2014 is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-016650 | Jan 2014 | JP | national |
