JP6590317B2 - Droplet volume measuring device and measuring method - Google Patents

Description

  In the present invention, in order to control the flow rate of a chemical solution drip, a falling droplet image is processed by irradiating a falling droplet with parallel light and processing a droplet shadow image acquired by an image sensor. The present invention relates to a droplet amount measuring apparatus and a measuring method for calculating a liquid velocity.

  The infusion pump used to control the flow rate of medicinal fluids uses an infusion tube that is highly scalable and elastic. inject. Since infusion pumps are easily affected by the height, inclination, viscosity, and resistance of tubes and blood vessels of chemical liquid bottles, currently available infusion pumps have a flow rate error of about ± 10%.

  Accurate flow measurement is required to ensure accurate and stable infusion and infusion. The drop number control method counts the number of dropped droplets under the assumption that the size of each droplet is constant, and calculates the amount and speed of liquid drop. However, flow rate errors occur due to differences in the viscosity coefficient of the drugs and the size of the droplets being not the same.

  Conventionally, in order to reduce the flow rate error of such a droplet number control method and accurately measure the amount of dropped droplets, an image sensor for photographing the droplets is used to obtain the liquid droplet shape from the acquired shape of the droplet shadow. An infusion detection device that obtains a highly accurate flow rate by calculating the droplet volume has been developed.

  FIG. 4 is a diagram for explaining the principle of the conventional droplet amount measurement. To measure the amount of liquid droplets, as shown in the figure, the dripping nozzle, the light source disposed on the side surface of the liquid droplet falling from the dripping nozzle, and the light source disposed opposite to the falling liquid droplet were disposed. 2D image sensor. The image sensor is formed using a CMOS (metal oxide semiconductor device), a CCD (charge coupled device), etc., and each pixel is arranged in a matrix (array) to capture a two-dimensional image, and a droplet shadow image To get. By calculating the droplet volume from the acquired droplet shadow image, the droplet flow rate can be acquired. However, if the timing at which the droplet starts to fall cannot be accurately detected, the entire image of the droplet shadow cannot be captured.

  FIG. 5A is a diagram for explaining the concept of droplet amount measurement based on the prior art disclosed in Patent Document 1, and FIG. 5B calculates a volume from a droplet image determined to be in a droplet falling state. It is a figure explaining a method. Patent document 1 discriminate | determines the moment when a chemical | medical solution falls off a dripping nozzle based on the imaging | photography data from the image sensor which takes in a two-dimensional image.

  In FIG. 5A, a droplet drop state is detected using each detection image of an upper detection sensor and a lower detection sensor corresponding to a part of an image sensor that captures a two-dimensional image. The upper detection sensor is provided in a region close to the lower end of the dropping nozzle and slightly below the residue, and the lower detection sensor is lower than the dropping nozzle and slightly lower than the constricted portion. Provide in the area. In the state before the droplet is dropped, the droplet is connected to the residue via the constricted portion. By detecting the presence / absence of the constricted portion, it is possible to detect whether the droplet is in a state before the droplet is dropped, or whether the droplet is dropped into a droplet and a residue.

  Next, the volume is calculated as shown in FIG. 5B using the droplet image determined to be in the droplet falling state. As shown in the figure, it is assumed that an image of a droplet is divided into n rectangles having a minute height h, and an actual droplet is formed by stacking n disks each having a diameter of the rectangle. Then, the volume of the n disks is calculated from the width and height of the rectangle, and the total is set as the volume of the droplet (that is, the volume is calculated by the division quadrature).

  In this way, it is possible to detect a droplet falling state by using a part of an image sensor that captures a two-dimensional image as a drop detection sensor without requiring a sensor for detecting the drop of the droplet. However, since the drop speed of the droplet is relatively high, it is impossible to completely solve the problem that it is difficult to capture the entire image of the droplet shadow.

  6A and 6B are diagrams for explaining the problem that it is difficult to capture the entire image of the droplet shadow. FIG. 6A is a side view of the droplet amount measuring apparatus, and FIG. The droplet shadow of is illustrated. As shown in FIG. 6 (A), a light source (laser) disposed on the side of a falling droplet and a two-dimensional image sensor disposed at a position facing the light source across the falling droplet. Yes. FIG. 6B illustrates four captured images captured at intervals of 0.005S in time. Thus, since the drop speed is relatively high, it is difficult to capture the entire image of the droplet shadow with the image sensor.

JP2011-62371

  Therefore, the present invention solves such a problem and makes it possible to capture the entire image of the photographed droplet shadow even with the use of an image sensor in a relatively small area. ) It aims to realize the drip amount measurement.

Using the image sensor placed on the opposite side of the light source across the drip tube, the generated shadow image is displayed by collimating the light from the light source and irradiating the falling droplet and the drop space of the droplet from the dropping nozzle. To detect. The contour of the shadow image is processed to recognize the shape of the droplet, and the droplet flow rate or liquid feeding speed is calculated from the shape of the droplet.

According to the droplet amount measuring apparatus and method of the present invention, a convex lens is disposed between the drip tube and the image sensor, and the convex lens is used to reduce at least the length in the droplet dropping direction, and from the tip of the dropping nozzle. An image of the drop space over the entire length of the drop falling distance to the surface of the liquid reservoir in the drip tube is acquired by the image sensor, and the falling droplet is determined by discriminating the droplet portion in the acquired image. Get the entire shadow image.

The convex lens has a lens diameter sufficient to receive the parallel light over the entire length of the drop falling distance from the tip of the dropping nozzle to the surface of the liquid reservoir in the drip tube, and is reduced in at least the drop dropping direction with respect to the incident light. A cylindrical convex lens that gives a change and forms a linear focused beam at the focal plane is preferred. Calculating the droplet flow rate or feed rate of the dropping direction droplets from the volume of the droplets obtained is regarded as a rotating body with the left and right symmetry and the axis.

  The light source is a laser, an LED, a light-emitting lamp, or an organic EL surface light source that can irradiate parallel rays over the entire length of the droplet dropping distance from the tip of the dropping nozzle to the surface of the liquid pool. This light source can be made into a parallel light beam by interposing a beam expander in the diffusion optical path before the dropping nozzle.

  The image sensor is a CMOS or CCD that captures a two-dimensional image by arranging each pixel in a matrix having a droplet drop direction and a width direction perpendicular thereto, and at least the tip of the drop nozzle in the droplet drop direction. In the width direction, the entire length from the liquid reservoir to the liquid reservoir is reduced by the convex lens, and the width is at least equal to the droplet shadow.

  And a control unit that connects to the light source and issues a lighting command, and connects to the image sensor to capture a binarized image of the shadow image, stores it in a storage unit, and The control unit instructs the calculation unit to calculate the droplet flow rate or the liquid feeding speed from the volume of the droplet obtained from the binarized image stored in the storage unit. A display unit that displays the calculated droplet flow rate or liquid feeding speed, or an administration driving unit that controls the flow rate flowing through the drip tube based on the calculated droplet flow rate or liquid feeding speed is provided.

  According to the present invention, it is possible to capture the entire image of the captured shadow of the droplet even using an image sensor in a relatively small area, and accurately calculate the droplet volume from the droplet shadow of the entire image. It is possible to obtain a droplet flow rate with a proper value. By using this acquired droplet flow rate value, for example, by controlling an infusion pump, the flow accuracy when using a current general infusion pump is ± 10%, which is ± 1% of 1/10 or less. Flow accuracy can be achieved.

It is a figure which illustrates the outline of the droplet amount measuring apparatus comprised based on this invention. It is a figure which illustrates the outline of another droplet amount measuring apparatus different from FIG. 1, (A) is cut | disconnected by the droplet part which falls, and the top view seen from the top, (B) is the liquid which falls. It is the side view cut | disconnected by the drop part. It is a figure explaining the method of calculating the volume of a droplet from a droplet image. It is a figure explaining the principle of the conventional droplet amount measurement. (A) is a figure explaining the concept of the droplet amount measurement based on the prior art disclosed in Patent Document 1, and (B) is a method for calculating a volume from a droplet image determined to be a droplet falling state. It is a figure explaining. It is a figure explaining the problem that it is difficult to capture the entire image of the droplet shadow, (A) shows a side view of the droplet amount measuring device, and (B) is a droplet shadow that is falling Is illustrated.

  FIG. 1 is a diagram illustrating an outline of a droplet amount measuring apparatus constructed according to the present invention. In the exemplary droplet amount measuring apparatus, the light from the light source is converted into parallel light, irradiated to the falling droplet from the dropping nozzle, and the shadow generated by the image sensor placed on the opposite side of the light source with the drip tube interposed therebetween. Is detected. The portion blocked by the droplet becomes a shadow, and as a result, the image sensor can reflect the shape of the droplet. By processing the contour of the shadow image, the shape of the chemical solution can be recognized.

  In such a droplet amount measuring apparatus, the present invention reduces the shadow generated by the droplet using a cylindrical convex lens and generates it over the entire length of the long drop distance (only the drop direction) from the tip of the drop nozzle. The obtained shadow is acquired by an image sensor, and the volume is obtained using the symmetry of the droplet. As is well known, the cylindrical convex lens is a convex lens in which at least one surface of the lens surface has a cylindrical surface shape. The cylindrical convex lens can change only the uniaxial direction with respect to the incident light, and can form a linear condensed beam on the focal plane.

  In FIG. 1, the drip tube is a well-known one that drops a chemical solution from a drip nozzle provided at the top and feeds it from an drip tube provided at the lowermost end. When infusion is performed using an infusion pump or a natural drop, the chemical solution falls from the dropping nozzle and is stored as a liquid reservoir below the drip tube. At this time, the chemical solution is not immediately dropped due to the influence of the surface tension but is stored in a state of being held by the dropping nozzle. When the amount of the chemical liquid held by the dropping nozzle exceeds a certain value, the gravity is larger than the surface tension, so that the chemical liquid leaves the dropping nozzle and falls as a droplet.

  The light source can be a laser, LED, a light emitting lamp such as a normal bulb, or an organic EL, etc., as long as it can irradiate parallel rays over the entire length of the droplet drop from the tip of the dropping nozzle to the surface of the liquid pool A surface light source or the like can be used. Moreover, as illustrated in FIG. 2 to be described later, it is also possible to use a parallel light beam with a collimator lens interposed in the diffusion light path before the dropping nozzle.

  The image sensor is formed using a CMOS (metal oxide semiconductor device), a CCD (charge coupled device), or the like, and takes in a two-dimensional image by arranging at least each pixel in a matrix (array). The array length of the image sensor in the drop drop direction is equal to or greater than the total length from the tip of the drop nozzle to the liquid reservoir reduced by the cylindrical lens, and the array width of the image sensor perpendicular to the array length direction. Is greater than or equal to the width of the drop shadow.

  The control unit is connected to the light source and issues a lighting command, while being connected to the image sensor, the binarized image of the two-dimensional image is captured and stored in the storage unit. The droplets are photographed continuously, and the binarized image is captured at a predetermined timing. As described above, the present invention reduces the drop shadow using a convex lens and can capture an image over the entire length of the long drop distance. Therefore, the conventional technology as described with reference to FIGS. It does not require strict image capture timing. In the present invention, it is possible to use a dedicated detection sensor for detecting the image capturing timing, but without providing a separate detection sensor, for example, only the upper part of the illustrated image sensor (in the direction of droplet drop). It can be switched to shoot continuously and shoot the entire area when there is a change (falling).

  Alternatively, by setting the binarized image capture speed appropriately in advance corresponding to the set infusion supply amount, only one droplet is captured in the acquired image. Is possible. For example, in the case of a commercially available infusion pump (TE-161S), since the maximum supply amount is 500 ml / h, it becomes 3 drops or less per second (in the case of an infusion set 0.05 ml / drop). Therefore, in this case, it can be set so that two or more drops are not measured simultaneously. However, in addition to this droplet, satellite droplets of about 0.4% of the volume may fall at the same time. If this satellite droplet is continuously ignored, an error of + 0.4% at maximum is estimated. In this case, if two or more drops are detected at the same time, the volume of each drop can be obtained individually using the same calculation method if an algorithm is provided that divides the image into the main drop and each drop of the satellite liquid. become.

  Further, the control unit instructs the calculation unit to obtain a necessary volume from the binarized image stored in the storage unit, and calculates a flow rate (liquid feeding speed) as will be described later. Further, the control unit displays the calculated flow rate (liquid feeding speed) on the display unit. Further, based on the calculated flow rate (liquid feeding speed), the administration driving unit that controls the flow rate flowing through the drip tube is controlled. The administration driving unit includes, for example, an infusion pump or a tube pressing unit and a motor for driving the infusion pump, and controls the flow rate in the tube based on the calculated flow rate. For example, the flow rate is controlled by adjusting the number of times per hour when the tube is handled. Specifically, when the detected volume is ± x% smaller than the target value, the next timing of handling the tube is always shortened or lengthened to compensate for that x%. Alternatively, it is possible to control an adjustment valve for controlling the speed of liquid feeding due to natural fall based on the calculated flow rate.

  In the present invention, a shadow generated by irradiating light from a light source is reduced using a cylindrical convex lens, and is acquired over a long fall distance. What needs to be reduced using the cylindrical convex lens is the direction in which the liquid drops, and does not need to be reduced in the width direction perpendicular thereto. However, the size in the width direction of the image sensor can be reduced by reducing the width in the width direction. The cylindrical convex lens is disposed between the drip tube and the image sensor. The light source generates parallel light over the entire length of the drip drop from the tip of the dropping nozzle to the liquid reservoir, and the cylindrical convex lens has a diameter that can receive at least the entire parallel light from the light source. For example, when a cylindrical convex lens having a lens diameter (or lens width) of 20 mm and a focal length of 50 mm is used to reduce to 1/4 in the dropping direction, a CMOS element having a height of 5 mm is used as an image sensor and 40 mm from the cylindrical convex lens. Place at the position. As a result of measurement with such an arrangement, measurement accuracy of ± 0.25% (± 1% or less) was obtained.

  FIG. 2 is a diagram illustrating an outline of another droplet amount measuring apparatus different from FIG. 1, (A) is a plan view cut from the falling droplet portion and viewed from above, and (B). FIG. 6 is a side view taken along a falling droplet part. In FIG. 2, a beam expander using two collimator lenses having focal lengths f1 and f2 is disposed between the light source and the drip tube. A beam expander is well known as an optical system used when a beam is expanded into a parallel light beam having a constant magnification. Using such a beam expander, a wide range of imaging can be made possible.

FIG. 3 is a diagram illustrating a method for calculating the volume of a droplet from a droplet image. Even if the shape of the droplet changes, there is left-right symmetry, so it can be regarded as a rotating body with the drop direction as the axis. Therefore, since the image sensor has pixels in each width direction line arranged in a matrix in the vertical direction, the length in each width direction line direction from the acquired shadow image is set as the diameter a, and each width direction line. To detect. Using the detected diameter a of each cross section, the volume of the droplet can be obtained by integration of the rotating body. This volume calculation method itself is the same as that of the prior art described with reference to FIG.

Claims (9)

Using the image sensor placed on the opposite side of the light source across the drip tube, the generated shadow image is displayed by collimating the light from the light source and irradiating the falling droplet and the drop space of the droplet from the dropping nozzle. In the droplet amount measuring device that detects and recognizes the shape of the droplet by processing the contour of the shadow image, and calculates the droplet flow rate or the liquid feeding speed from the shape of the droplet,
A convex lens is disposed between the drip tube and the image sensor, and this convex lens reduces at least the length of the droplet dropping direction, and drops the droplet from the tip of the dropping nozzle to the surface of the liquid reservoir in the drip tube. A droplet configured to acquire an image of the falling space over the entire distance by the image sensor and to acquire a shadow image of the entire falling droplet by determining a droplet portion in the acquired image. Quantity measuring device. The convex lens has a lens diameter that only receives the parallel light over the entire length of the droplet drop from the tip of the drop nozzle to the surface of the liquid reservoir in the drip tube, and only the drop drop direction changes with respect to the incident light. The droplet amount measuring apparatus according to claim 1, which is a cylindrical convex lens that gives a linear condensed beam at a focal plane. The droplet amount measurement according to claim 1, wherein the droplet flow rate or the liquid feeding speed is calculated from the volume of the droplet obtained by regarding the droplet as a rotating body having left-right symmetry about the drop direction. apparatus. 2. The light source according to claim 1, wherein the light source is a laser, an LED, a light-emitting lamp, or an organic EL surface light source capable of irradiating parallel rays over the entire length of the droplet dropping distance from the tip of the dropping nozzle to the surface of the liquid pool. Droplet volume measuring device. The droplet amount measuring apparatus according to claim 4, wherein the light source is formed into a parallel light beam with a beam expander interposed in a diffusion light path before the dropping nozzle. The image sensor is a CMOS or CCD that captures a two-dimensional image by arranging each pixel in a matrix having a droplet drop direction and a width direction orthogonal thereto, and at least a drop nozzle in the droplet drop direction. The droplet amount measuring device according to claim 1, wherein the entire length from the tip to the liquid reservoir is reduced by the convex lens and has a width that is at least equal to a droplet shadow in the width direction. A control unit that connects to the light source and issues a lighting command, and connects to the image sensor to capture a binary image of the shadow image, stores the binarized image in a storage unit, and 4. The droplet amount according to claim 3, wherein the control unit instructs the calculation unit to calculate a droplet flow rate or a liquid feeding speed from a droplet volume obtained from the binarized image stored in the storage unit. measuring device. 8. The display device according to claim 7, further comprising: a display unit that displays the calculated droplet flow rate or liquid feeding speed, or an administration driving unit that controls a flow rate flowing through the drip tube based on the calculated droplet flow rate or liquid feeding speed. Droplet volume measuring device. Using the image sensor placed on the opposite side of the light source across the drip tube, the generated shadow image is displayed by collimating the light from the light source and irradiating the falling droplet and the drop space of the droplet from the dropping nozzle. In the droplet amount measuring method for acquiring and processing the contour of the shadow image to recognize the shape of the droplet, and calculating the droplet flow rate or the liquid feeding speed from the shape of the droplet,
A convex lens is disposed between the drip tube and the image sensor, and this convex lens reduces at least the length of the droplet dropping direction, and drops the droplet from the tip of the dropping nozzle to the surface of the liquid reservoir in the drip tube. A droplet amount measuring method for acquiring an image of the falling space over the entire distance by the image sensor and determining a shadow image of the entire falling droplet by determining a droplet portion in the acquired image .

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