Volume measuring device and volume measuring method

Abstract

To provide a measurement object cubic volume measuring device and cubic volume measuring method with which it is possible to achieve downsizing.SOLUTION: Provided is a cubic volume measuring device 10 for deriving the cubic volume of a measurement object W from the shape and size of a shadow image and having a light source 11 that emits diffusing light and an image sensor 12 that detects the measurement object W irradiated with light as a shadow image. The cubic volume measuring device 10 further includes a telecentric member 15 for parallelizing diffused light and irradiating the measurement object W with it, and an optical path expansion member 14 provided on an optical path from the light source 11 to the telecentric member 15, for extending the optical path by the reflection of light.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a volume measuring device and a volume measuring method for deriving the volume of a measurement object. [Background technology]

[0002] When administering a drug solution by drip infusion, it is necessary to keep the amount of injection per unit time (hereinafter also referred to as the "infusion rate") within an appropriate range. Conventionally, the injection rate of a drug has been confirmed by visually counting the number of droplets falling per unit time inside the chamber (drip tube) of the drip device. This is based on the assumption that the volume of each falling droplet is equal, but it has been confirmed that the actual volume of the droplets varies depending on the influences of the ambient temperature, humidity, and viscosity of the drug, etc.

[0003] Therefore, in order to precisely detect the injection rate of the drug, it is effective to measure the volume of each droplet, and a specific example thereof is described, for example, in Patent Document 1. Patent Document 1 describes a method in which a light source that irradiates light onto the droplets and an image sensor that detects the shadow created by the light source irradiating the droplets as a shadow image are disposed on both sides of the chamber of the drip device, and the volume of the droplets is calculated based on the shadow image.

[0004] A telecentric component is provided between the light source and the chamber to collimate the diffusing light emitted from the light source and direct it toward the droplets, ensuring that the calculated volume of the droplets is not affected even if the distance between the image sensor and the falling droplets varies for each individual droplet. Furthermore, in the method of Patent Document 1, focusing on the fact that a droplet has a rotationally symmetric shape, the droplet is assumed to be a stack of tiny cylinders as shown in Fig. 7, and the volume of the droplet is calculated by adding up the volumes of all the cylinders. If the height of each cylinder is dh and the diameter of the cylinder is D(h), the calculation formula for the volume V of the droplet is given by the following Equation 1.

[0005]

number

[0006] According to Equation 1, since the square of the diameter of the cylinder is used to calculate the volume of the droplet, the diameter of the cylinder, i.e., the horizontal length of the shadow image, is highly sensitive to the calculated value of the volume of the droplet. Here, Patent Document 1 describes that a cylindrical lens (cylindrical convex lens) is provided between the chamber and the image sensor, and the image sensor detects an image in which the length in the vertical direction (i.e., the direction in which the droplet falls) is compressed without changing the horizontal length. This expands the vertical detection range of the image sensor without reducing the horizontal length, which has a large effect on the measurement of the droplet volume, and enables the image sensor to reliably capture the entire droplet as it falls. Therefore, the method described in Patent Document 1 enables highly accurate (e.g., an error of 1% or less) measurement of the droplet volume. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2017-072497 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the method described in Patent Document 1, it was necessary to increase the distance from the light source to the telecentric member in order to suppress aberration when detecting droplets with the image sensor. As a result, the distance from the light source to the image sensor became longer, leading to a problem that the entire device became larger. The object of measurement of the volume by the method described in Patent Document 1 is not limited to liquid droplets, but may also be, for example, the volume of a solid object. The present invention has been made in view of the above circumstances, and has an object to provide a device for measuring the volume of an object to be measured, which can be made compact, and a volume measuring method using the same. [Means for solving the problem]

[0009] A volume measuring device according to a first aspect of the present invention that meets the above-mentioned objective has a light source that emits diffused light, and an image sensor that detects a shadow image of a measured object onto which the light is irradiated, and derives the volume of the measured object from the shape and size of the shadow image.The volume measuring device further comprises a telecentric member that collimates the diffused light and irradiates it onto the measured object, and an optical path extension member that is provided on the optical path from the light source to the telecentric member and that lengthens the optical path by reflecting the light.

[0010] A volume measurement method according to a second aspect of the present invention that meets the above-mentioned objective includes providing an optical path extension member that lengthens the path of light by reflecting the light on the path from a light source that emits diffusing light to a telecentric member that collimates the diffusing light and irradiates the light onto the object to be measured, detecting the object to be measured as a shadow image using an image sensor, and deriving the volume of the object to be measured from the shape and size of the shadow image.

[0011] A volume measuring method according to a third invention that meets the above-mentioned objective is a volume measuring method for measuring the volume of a measurement object moving within a translucent chamber, in which light is emitted from a light source so that the optical axis center (diffusion central axis) is parallel to the movement direction of the measurement object, the light from the light source is reflected by an optical element to pass through the chamber from one side to the other, and then reflected by a reflecting element to pass through the chamber from the other side to one side, and is guided to an image sensor by reflection by the optical element, the measurement object is detected as a shadow image by the image sensor, and the volume of the measurement object is derived based on the shadow image.

[0012] A volume measuring method according to a fourth invention that meets the above-mentioned objective is a volume measuring method for measuring the volume of an object to be measured, in which light is emitted from a light source so that the center of the optical axis (central diffusion axis) is parallel to the direction in which the object to be measured moves or the longitudinal direction of the object to be measured, the light from the light source is reflected by an optical element and irradiated towards the object to be measured from one side, and is reflected by a reflecting element and irradiated towards the object to be measured from the other side, and is guided to an image sensor by reflection by the optical element, the image sensor detects the object to be measured as a shadow image, and the volume of the object to be measured is derived based on the shadow image. Effect of the Invention

[0013] The volume measuring device according to the first invention includes a telecentric member that collimates the diffusing light and irradiates the object to be measured, and an optical path extension member that is provided on the optical path from the light source to the telecentric member and that lengthens the optical path by reflecting light, so that it is possible to make the device compact. Also, the volume measuring method according to the second invention includes an optical path extension member that lengthens the optical path by reflecting light, provided on the optical path from the light source that emits diffusing light to the telecentric member that collimates the diffusing light and irradiates the object to be measured, so that the device to which the volume measuring method can be applied can be made compact.

[0014] The volume measuring device according to the third invention emits light from a light source so that the optical axis center is parallel to the moving direction of the object to be measured, and the light from the light source is reflected by an optical member to pass through the chamber from one side to the other, then reflected by a reflecting member to pass through the chamber from the other side to the one side, and guided to the image sensor by reflection by the optical member, so that the device to which the volume measuring method can be applied can be made compact.Furthermore, the volume measuring device according to the fourth invention emits light from a light source so that the optical axis center is parallel to the moving direction of the object to be measured or the longitudinal direction of the object to be measured, and the light from the light source is reflected by an optical member to be irradiated from one side towards the object to be measured, and reflected by a reflecting member to be irradiated from the other side towards the object to be measured, and guided to the image sensor by reflection by the optical member, so that the device to which the volume measuring method can be applied can be made compact. [Brief description of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram of a volume measuring device according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 13 is an explanatory diagram of a volume measuring device according to a modified example. [Figure 4] 1A and 1B are explanatory diagrams showing the measurement results of the volume of a water droplet. [Diagram 5] FIG. 13 is an explanatory diagram showing an image obtained in an experiment. [Figure 6] FIG. 13 is an explanatory diagram showing measurement of the volume of liquid falling continuously. [Figure 7] FIG. 4 is an explanatory diagram showing a method for measuring the volume of a droplet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Next, with reference to the attached drawings, an embodiment of the present invention will be described for better understanding of the present invention. 1 and 2, a volume measuring device 10 according to an embodiment of the present invention has a light source 11 that emits diffusing light, and an image sensor 12 that detects a shadow image of a droplet W, which is an example of a measurement target irradiated with light, and derives the volume of the droplet W from the shape and size of the shadow image. A detailed description will be given below.

[0017] In this embodiment, as shown in Fig. 1 and Fig. 2, the volume measuring device 10 includes a light source 11 that emits (outputs) a diffusing laser light, a beam splitter 13 through which the laser light emitted from the light source 11 passes, a pentaprism (an example of an optical path expansion member) 14, and a telecentric lens (an example of a telecentric member) 15, a reflecting member 16 that reflects the laser light that has passed through the telecentric lens 15, a cylindrical lens 17 into which the laser light that has been reflected by the reflecting member 16 and passed through the telecentric lens 15, the pentaprism 14, and the beam splitter 13 in that order is incident, and an image sensor 12 that receives the laser light that has passed through the cylindrical lens 17. As the image sensor 12, a CMOS or a CCD is preferably used. In addition, when simply counting droplets or detecting whether droplets pass or do not pass, a simple light receiving element (such as a photodetector) may be used instead of the image sensor 12.

[0018] For the light source 11, it is useful to irradiate a laser beam with low coherence and diffusivity in order to improve various characteristics, but a light beam with high coherence and low diffusivity may be used depending on the specifications of the device, etc. Note that light sources that can be used include those that irradiate light other than laser beams, such as LEDs, but laser beams are preferable from the viewpoint of directivity, etc.

[0019] The wavelength of the light emitted by the light source 11 can range from the infrared region including the visible region to the ultraviolet region, but in consideration of costs, it is preferable to use red laser light. It is also preferable to select an optimal wavelength depending on the type of object to be measured (constituent materials, contained substances, etc.). Although the present embodiment uses one light source 11, multiple light sources may be used depending on the specifications of the device, the convenience of the assembly process, etc. When multiple light sources 11 are used, they may be configured to emit different light beams from each other.

[0020] Beam splitter 13 is substantially cube-shaped and is disposed above light source 11 (between light source 11 and pentaprism 14) with two opposing flat surfaces disposed substantially horizontally. In beam splitter 13, the lower of the two horizontally disposed flat surfaces is hereinafter referred to as "lower surface 13c," and the upper surface is hereinafter referred to as "upper surface 13d." Beam splitter 13 splits incident light into transmitted light and reflected light at splitting surface 13a.

[0021] The pentaprism 14 is provided above the beam splitter 13, and is fixed with one horizontally disposed flat surface (hereinafter referred to as "lower surface 14d") in surface contact with the upper surface 13d of the beam splitter 13. In this embodiment, the lower surface 14d of the pentaprism 14 and the upper surface 13d of the beam splitter 13 are bonded together with an optical adhesive having substantially the same refractive index as that of the beam splitter 13. As shown in FIG. 1, the pentaprism 14 is designed so that light incident on the lower surface 14d is reflected twice by the reflecting surfaces 14a and 14b, and exits from one surface (hereinafter referred to as "front surface 14c") perpendicular to the lower surface 14d. In this embodiment, the pentaprism 14 and the beam splitter 13 are bonded together with an optical adhesive, but they may be disposed with a gap therebetween.

[0022] The telecentric lens 15 has a convex surface on one side and a flat surface on the other side (hereinafter referred to as the "back surface"), and the back surface is in close contact with the front surface 14c of the pentaprism 14. Laser light (hereinafter also simply referred to as "light") incident on the pentaprism 14 in a direction perpendicular to the lower surface 14d of the pentaprism 14 exits from the front surface 14c of the pentaprism 14 in a direction perpendicular to the front surface 14c (i.e., horizontal) while light incident on the pentaprism 14 in a direction non-perpendicular to the lower surface 14d of the pentaprism 14 exits from the front surface 14c of the pentaprism 14 in a direction non-perpendicular to the front surface 14c (i.e., non-horizontal). The telecentric lens 15 passes both the light exiting from the front surface 14c of the pentaprism 14 in a direction perpendicular to the front surface 14c and the light exiting in a non-perpendicular direction horizontally (i.e., parallel).

[0023] That is, the telecentric lens 15 converts the light coming out of the front surface 14c of the pentaprism 14 into parallel light. In this embodiment, the telecentric lens 15 and the pentaprism 14 are abutted against each other and bonded with an optical adhesive, but the telecentric lens 15 and the pentaprism 14 may be arranged with a gap therebetween depending on the specifications of the device and the convenience of the assembly process. In this embodiment, the telecentric lens 15 and the pentaprism 14 are configured as separate members, but a single optical member having the functions of both the telecentric lens and the pentaprism may be provided. For example, the optical member can be formed by processing the front surface 14c of the pentaprism 14 to provide the same function as the telecentric lens. In this case, the number of parts is reduced, or the positioning process can be eliminated, which is advantageous in terms of cost.

[0024] The reflecting member 16 is a glass plate on which a metal film is formed by vapor deposition, and is disposed vertically at the same height as the pentaprism 14 and telecentric lens 15, and at a distance from the telecentric lens 15. It goes without saying that the light source 11, beam splitter 13, pentaprism 14, telecentric lens 15 and reflecting member 16 are supported by members not shown.

[0025] Between the telecentric lens 15 and the reflecting member 16, there is provided a light-transmitting chamber T of the drip device, within whose inner space the liquid droplets W fall intermittently. A cylindrical lens 17 that reduces the image in the vertical direction is fixed in surface contact with one of the vertical surfaces of the beam splitter 13 (hereinafter referred to as the "rear surface 13b"), and an image sensor 12 is provided at the same height as the beam splitter 13 and cylindrical lens 17, but at a distance from the cylindrical lens 17.

[0026] Furthermore, the cylindrical lens 17 is bonded to the beam splitter 13 using an optical adhesive in a state where it is in contact with the beam splitter 13, but it may also be fixed with a gap provided between the beam splitter 13 and the cylindrical lens 17. In this case, whether to have it in a state where it is in contact with the beam splitter 13 or to have a gap is appropriately selected depending on the specifications of the device, the assembly process, etc. Furthermore, in this embodiment, the beam splitter 13 and the cylindrical lens 17 are configured as separate bodies, but it is also possible to process the back surface 13b of the beam splitter 13 to form an optical member having substantially the same function as the cylindrical lens 17. In this case, the number of parts is reduced, or the positioning process can be eliminated, which is advantageous in terms of cost.

[0027] The diffusing light emitted from the light source 11 travels upward, enters the beam splitter 13 from its lower surface 13c, and is split by splitting surface 13a inside the beam splitter 13, with one of the split light beams (in this embodiment, the transmitted light that has passed through splitting surface 13a) exiting from the upper surface 13d of the beam splitter 13. The light that exits from the upper surface 13d of the beam splitter 13 enters the pentaprism 14 from its lower surface 14d, is reflected by reflecting surface 14a, and is further reflected by reflecting surface 14b, i.e., is reflected twice, before exiting from the front surface 14c of the pentaprism 14 and entering the telecentric lens 15.

[0028] Therefore, the beam splitter 13 provided between the light source 11 and the pentaprism 14 splits the light emitted by the light source 11 and directs the split light consisting of either transmitted light or reflected light toward the pentaprism 14. Also, by providing the pentaprism 14 and reflecting the light toward the telecentric lens 15, the optical path from the light source 11 to the telecentric lens 15 is made longer than when the light from the light source 11 is directed toward the telecentric lens 15 without being reflected. In other words, the pentaprism 14 lengthens the optical path from the light source 11 to the telecentric lens 15 by reflecting the light.

[0029] The light incident on the telecentric lens 15 passes through the telecentric lens 15, and a portion of the light strikes the droplet W, while the remaining light strikes the reflecting member 16 directly and is substantially totally reflected, as shown in Figures 1 and 2. Therefore, the telecentric lens 15 collimates (horizontally in this embodiment) the light that is emitted from the front surface of the pentaprism 14 and diffuses, and irradiates the light onto the droplet W.

[0030] The light reflected by the reflecting member 16 travels horizontally toward the telecentric lens 15, passes through the telecentric lens 15, changes its vertical component, and enters the pentaprism 14 from the front surface 14c of the pentaprism 14. Therefore, the reflecting member 16 is provided downstream in the traveling direction of the light irradiated onto the droplet W (chamber T) via the telecentric lens 15, and reflects the light toward the pentaprism 14. The light that enters the pentaprism 14 is reflected by reflecting surface 14b and then reflected by reflecting surface 14a further ahead, i.e., after being reflected twice, travels vertically, exits from the lower surface 14d of the pentaprism 14, and enters the beam splitter 13 from the upper surface 13d of the beam splitter 13.

[0031] The light incident on beam splitter 13 is split by splitting surface 13a inside beam splitter 13, and one of the split lights (in this embodiment, the light reflected by splitting surface 13a) exits horizontally from rear surface 13b arranged vertically of beam splitter 13. The light exiting rear surface 13b of beam splitter 13 enters cylindrical lens 17 from the flat side of cylindrical lens 17, and when exiting from the convex side of cylindrical lens 17, the vertical component is changed (only the light incident on the center in the height direction of cylindrical lens 17 does not change the vertical component) and heads toward image sensor 12.

[0032] The image sensor 12 receives the light emitted from the cylindrical lens 17 and detects a shadow image in which the liquid droplet W appears as a shadow. Thus, the image sensor 12 captures the split light (in this embodiment, the reflected light) consisting of the other of the transmitted light and the reflected light split by the beam splitter 13, which is reflected by the reflecting member 16 and further reflected by the pentaprism 14 (i.e., the light path is lengthened by reflection by the reflecting member 16 and the pentaprism 14).

[0033] Here, the telecentric lens 15 is used to horizontalize the light that is diffused and emitted from the front surface 14c of the pentaprism 14 so that the shadow images of the droplets W detected by the image sensor 12 will be the same size for droplets W of the same size, even if the distance from the droplets W to the pentaprism 14 to which the light is irradiated varies for each droplet W. In addition, the cylindrical lens 17 reduces the vertical component of the overall image detected by the image sensor 12 (the image detected over the entire detection range of the image sensor 12), thereby expanding the area detectable by the image sensor 12 in the vertical direction, thereby enabling the image sensor 12 to stably capture the falling droplets W.

[0034] A calculation unit 18 that acquires a shadow image of the droplet W detected by the image sensor 12 is connected to the image sensor 12. The calculation unit 18 can be configured with a CPU, a storage device, etc., and performs image processing such as binarization on the shadow image of the droplet W, detects pixels corresponding to the droplet W, and calculates the volume of the droplet W using the calculation formula 1 based on the shape and size of the shadow image.

[0035] Although the volume measuring device 10 described so far employs the pentaprism 14 as the optical path extension member, the optical path extension member is not limited to the pentaprism 14 as long as it extends the optical path length by reflecting light. For example, instead of the pentaprism 14, the volume measuring device 20 may be designed using a triangular prism 21 as the optical path extension member as shown in Fig. 3. Note that in the volume measuring device 20, the same components as those in the volume measuring device 10 are denoted by the same reference numerals and detailed description thereof will be omitted.

[0036] The triangular prism 21 reflects light a total of two times, once on the outward path from the light source 11 to the reflecting member 16 and once on the return path from the reflecting member 16 to the image sensor 12, and therefore has a smaller expansion width of the optical path compared to the pentaprism 14, which reflects light a total of four times on the outward and return paths. Therefore, depending on the situation, it is necessary to ensure the optical path (light path) length from the light source 11 to the image sensor 12 by, for example, providing a space between the beam splitter 13 and the triangular prism 21 or between the triangular prism 21 and the telecentric lens 15.

[0037] In relation to this, it has been confirmed that when the beam splitter 13 and the telecentric lens 15 are fixed in close contact with the triangular prism 21 (or the pentaprism 14), it is easier to adjust the direction of light irradiation from the light source 11 and the relative positions of the light source 11, the beam splitter 13, the triangular prism 21 (or the pentaprism 14), the telecentric lens 15, etc., compared to when the beam splitter 13 and the telecentric lens 15 are fixed in a non-close contact state with the triangular prism 21 (or the pentaprism 14).

[0038] In addition, as shown in Figures 1 and 2, a volume measuring method using the volume measuring device 10 involves providing a pentaprism (an example of an optical path extension component) 14 that lengthens the optical path by reflecting light on the optical path from a light source 11 that emits diffusing light to a telecentric lens (an example of a telecentric component) 15 that collimates the diffusing light and irradiates it onto a droplet (an example of an object to be measured) W, detecting the droplet W as a shadow image using an image sensor 12, and deriving the volume of the droplet W from the shape and size of the shadow image.

[0039] From another perspective, in this embodiment, in order to realize the miniaturization of the device, the light source 11 emits diffused light so that the optical axis center (diffusion central axis) is parallel (including a nearly parallel state in which the optical axis center is slightly non-parallel to the extent that the characteristics and optical configuration do not change significantly) to the moving direction of the droplet W, which is an example of a measurement object moving in the chamber T, and the light from the light source 11 is reflected by various optical members (beam splitter 13, pentaprism 14, telecentric lens 15, cylindrical lens 17, etc.) to pass through the chamber T from one side to the other, then reflected by the reflecting member 16 to pass through the chamber T from the other side to one side, and guided to the image sensor 12 by reflection by the optical member, the image sensor 12 detects the droplet W as a shadow image, and the volume of the droplet W is derived based on the shadow image. With this configuration, the optical path can be made compact, and the device can be made compact.

[0040] In addition, in this embodiment, the light from the light source 11 is emitted in the opposite direction (vertically upward) to the moving direction (vertically downward) of the droplet W (i.e., the measurement target), but this is not limited to this. For example, by inverting the arrangement of various optical components up and down, the light source may be disposed above the pentaprism and light may be emitted in the forward direction (i.e., vertically downward) to the moving direction of the droplet W. Note that the various optical components themselves are preferably made of transparent materials such as optical glass or resin, and by molding them from resin, productivity, etc. can be improved. From yet another perspective, by placing the reflective member 16 on one side of the chamber T and placing various optical components such as the pentaprism 14, the light source 11 and the image sensor 12 on the other side, and concentrating the main components on the other side (one side), the distance between the components is shortened, and the installation accuracy and ease of installation can be improved, thereby improving productivity. EXAMPLES

[0041] Next, an experiment conducted to confirm the effects of the present invention will be described. In the experiment, the volume of water droplets falling inside the chamber of the drip device was measured using a TS N-BK7 Penta Prism 15mm VIS 0° penta prism manufactured by Edmund Optics Japan as the optical path extension component, a TS Cube Type B / S 50R / 50T 15mm manufactured by Edmund Optics Japan as the beam splitter, a TTS Plano Convex Lens 15x100 INK manufactured by Edmund Optics Japan as the telecentric lens, and a TS Illumination Cylinder Lens 12.5x25x15 manufactured by Edmund Optics Japan as the cylindrical lens.

[0042] The volume of the water droplets was measured for 10 droplets each when the droplet volume (drop rate) was a low speed of about 19.8 ml / h and a high speed of about 617 ml / h. The measurement results for each are shown in Figures 4(A) and (B). Note that the "average value" in the "error from the average value" in Figures 4(A) and (B) refers to the average value of the volumes of 10 droplets measured for both the low speed and the high speed. The experimental results showed that the error from the average value was less than ±2% for both the low speed and the high speed. FIG. 5 shows a shadow image 22 actually obtained by the image sensor and an image 23 obtained by binarizing the shadow image 22.

[0043] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and all changes in conditions that do not depart from the gist of the present invention are within the scope of application of the present invention. For example, the measurement object whose volume is measured by the volume measuring device is not limited to droplets, but may be a solid object, or may be liquid W' that falls continuously from a faucet 24 as shown in Fig. 6. Furthermore, the measurement object is not limited to a falling object, but may be a stationary object. The volume (flow rate per unit time) of liquid W' that falls continuously can be found from widths L1 and L2 of liquid W' at different height positions. In addition, multiple light sources, optical path extension members, telecentric members, and image sensors may be provided. By providing multiple of each of them, each image sensor can detect the measurement object from a different angle, making it possible to measure the volume of measurement objects of various shapes (i.e., shapes that are not rotationally symmetric).

[0044] Furthermore, the object to be measured is not limited to something that falls inside the chamber. For example, the object to be measured may be a pipe that conveys liquid or the like. In this case, light is irradiated so as to be wider than the width of the pipe, and is reflected by a reflective member, and changes in the shape of the pipe (expansion, contraction, deformation, etc.) are detected by an image sensor. This allows the volume measuring device to be used for detecting deterioration of the pipe, etc. In other words, if a problem occurs in the pipe for some reason, there is a high possibility that the condition of the pipe will be expressed in the form of a change in volume, and by measuring the volume with this device and method, it is possible to detect the problem in advance.

[0045] In this case, light is emitted from the light source so that the center of the optical axis is parallel to the longitudinal direction of the pipe, the light from the light source is reflected by an optical element and irradiated toward the pipe from one side, and then reflected by a reflecting element and irradiated toward the pipe from the other side, and the light is guided to an image sensor via reflection by the optical element, the image sensor detects the pipe as a shadow image, and the volume of the pipe is derived based on the shadow image, thereby making the entire device more compact. Furthermore, the present device and method can also be applied to measuring the flow rate of drip infusion devices that inject medicinal liquids into the human body, and of normal and small pumps, and can also be applied to measuring the liquid volume of cooling devices. [Explanation of symbols]

[0046] 10: volume measuring device, 11: light source, 12: image sensor, 13: beam splitter, 13a: splitting surface, 13b: rear surface, 13c: bottom surface, 13d: top surface, 14: pentaprism, 14a, 14b: reflecting surfaces, 14c: front surface, 14d: bottom surface, 15: telecentric lens, 16: reflecting member, 17: cylindrical lens, 18: computing unit, 20: volume measuring device, 21: triangular prism, 22: shadow image, 23: image, 24: faucet, T: chamber, W: droplet, W': liquid

Claims

1. A volume measuring device having a light source that emits diffusing light and an image sensor that detects a shadow image of a measurement object illuminated with the light, and deriving a volume of the measurement object from a shape and size of the shadow image, a telecentric member that collimates the diffusing light and irradiates the measurement object; a light path extension member that is provided on a light path from the light source to the telecentric member and that lengthens the light path by reflecting the light.

2. 2. The volume measuring device according to claim 1, further comprising a reflecting member that reflects the light irradiated onto the object to be measured via the telecentric member toward the optical path extension member downstream in the traveling direction of the light, and the image sensor captures the light that is reflected by the reflecting member and further reflected by the optical path extension member.

3. 3. A volume measuring device according to claim 2, further comprising a beam splitter between the light source and the optical path expansion member for splitting incident light into transmitted light and reflected light, the beam splitter splits the light emitted by the light source and directs the split light consisting of either the transmitted light or the reflected light toward the optical path expansion member, and the split light consisting of the other of the transmitted light and the reflected light is reflected in turn by the reflecting member and the optical path expansion member, enters the beam splitter and is captured by the image sensor.

4. 4. A volume measuring device according to claim 3, wherein the optical path expansion member is a pentaprism, the beam splitter is cube-shaped, and one flat surface of the beam splitter is in surface contact with one flat surface of the pentaprism.

5. a light path extending member for extending the light path by reflecting the light, the light path extending member being provided on a light path from a light source that emits diffusing light to a telecentric member that collimates the diffusing light and irradiates the measured object; A volume measuring method comprising the steps of: detecting the object to be measured as a shadow image by an image sensor; and deriving the volume of the object to be measured from the shape and size of the shadow image.

6. 6. The volume measuring method according to claim 5, further comprising providing a reflecting member downstream in the traveling direction of light irradiated onto the object to be measured via the telecentric member, which reflects the light toward the optical path extension member, and the image sensor captures the light reflected by the reflecting member and further reflected by the optical path extension member.

7. 7. The volume measuring method according to claim 6, further comprising: a beam splitter for dividing incident light into transmitted light and reflected light, provided between said light source and said optical path expansion member; said beam splitter divides the light emitted by said light source, and directs the divided light consisting of either the transmitted light or the reflected light toward said optical path expansion member; and said divided light consisting of the other of the divided transmitted light and the reflected light, which is reflected in turn by said reflecting member and said optical path expansion member, enters said beam splitter and is captured by said image sensor.

Images