A refractometer and an intelligent cup

Abstract

The present invention relates to the field of liquid refractive index measurement, and particularly to a refractometer and an intelligent cup. The present invention discloses a refractometer and an intelligent cup, wherein the refractometer includes a light source, a prism, a lens unit and a photoelectric sensor. The prism has a contact interface in contact with the liquid to be measured. The light source is a plurality of point light sources arranged in sequence at least in one direction. The light source is configured such that the light emitted by the light source enters the prism through the incident surface of the prism and irradiates the contact interface. The photoelectric sensor is disposed on the image-side focal plane of the lens unit. The light reflected from the contact interface exits the prism through the exit surface of the prism and is imaged on the photoelectric sensor by the lens unit with infinity focusing. The refractometer of the present invention has the advantages of low cost, small size, large measurement range and good robustness.

Description

Technical Field

[0001] The present invention belongs to the field of liquid refractive index measurement, and particularly relates to a refractometer and an intelligent cup having the refractometer. Background Art

[0002] A refractometer is a device for measuring the refractive index of a liquid. Since the dissolution of solid solutes will increase the refractive index of the liquid, the measurement of the refractive index can be used to measure the content of solid solutes. Therefore, a refractometer can be used to measure the content of solid solutes in a liquid. The solid solutes in an aqueous solution are usually sugars, so this device is called a saccharimeter in beverages (such as fruit juices, coffee, etc.). The unit of measurement of a saccharimeter is Brix.

[0003] As Figure 1 shown, the reflective electronic saccharimeter is a relatively common method for measuring sugar. Its principle is based on the fact that the total reflection angle is determined by the refractive indices of the two materials at the interface. According to Snell's law

[0004] sin(α 折射角 )*n 液体 =sin(α 入射角 )*n 玻璃

[0005] The total reflection angle β occurs

[0006]

[0007] That is to say, when the incident angle of light in the glass is greater than the total reflection angle β, there is only reflection. When the incident angle of light in the glass is less than the total reflection angle β, both transmission and reflection occur, and the brightness of the reflection is smaller than that during total reflection. We can see an obvious brightness change interface near the total reflection angle β. Through this interface, we can measure the total reflection angle β and thus calculate n 待测液体 (the refractive index of the liquid to be measured). Usually, the larger n 待测液体 is, the higher the total reflection angle β. Different glasses and liquids will give different angle values. For example, when n 玻璃 =1.5, the total reflection angle β of a 0-degree Brix aqueous solution is 62.73°, and the total reflection angle β of a 50-degree Brix aqueous solution is 71.2°.

[0008] In order to achieve a compact design, the refractometer disclosed in U.S. Patent: US7492447B2 (hereinafter referred to as the prior case) is provided with an essential slit 1′, as Figure 2As shown in the figure, the slit 1' is located behind the LED light source 2', such that the light-emitting point is very small in the direction parallel to the photosensitive array 3' (point light source). In this way, the angle of each beam of light hitting the photosensitive array 3' is well defined. Imagine if the slit 1' were not used, which means multiple point light sources emit light simultaneously. Then, light beams with different angles emitted by different point light sources might hit the same point on the photosensitive array 3', making it impossible to distinguish the angles of these light beams. And this angle is very important when determining the total reflection angle. The slit 1' essentially decouples the position and direction of the light rays, enabling us to detect only the direction of the light rays without being interfered by the position of the light rays. However, the main problem with this design is that the size required for the photosensitive array 3' would be very large, especially when a relatively large refractive index measurement range is required. Through the geometric equivalence of reflection, we can equivalently place the photosensitive array 3' on the liquid surface side, as Figure 3 shown in the figure. This makes it easier for us to understand the selection of the light path. It can be seen that at this time, the size l of the photosensitive array 3' = 2 * tan(α / 2) * d, where d represents the optical path distance from the LED light source 2' to the photosensitive array 3', and α is the overall angular spread. That is to say, if we require a relatively large α angle, such as when measuring different types of liquids with very different refractive index changes, the size of the photosensitive array 3' also needs to become very large. For a semiconductor chip like the photosensitive array 3' (CCD or CMOS), a larger physical size means higher costs. Considering the limited size of the semiconductor wafer, an increase in the device size will lead to a decrease in the production yield and the good product rate. A large-sized chip also means increased difficulty in packaging and chip mounting, and an increase in the chip mounting warpage rate, all of which will result in increased costs. Usually, due to such a large semiconductor size requirement, only a linear array (one-dimensional array) can meet the cost requirements. And the installation position and accuracy requirements of the linear array in the direction perpendicular to itself are very high, making the overall assembly more complex. Summary of the Invention

[0009] The object of the present invention is to provide a refractometer with low cost, small volume, large measurement range, and good robustness, as well as an intelligent cup with such a refractometer, in order to solve the above problems.

[0010] To achieve the above object, the technical solution adopted by the present invention is: a refractometer, comprising a light source, a prism, a lens unit, and a photoelectric sensor. The prism has a contact interface in contact with the liquid to be measured. The light source has a plurality of sequentially arranged point light sources at least in one direction. The light source is configured such that the light emitted by the light source enters the prism through the incident surface of the prism and irradiates the contact interface. The photoelectric sensor is disposed on the image-side focal plane of the lens unit. The light reflected from the contact interface exits the prism through the exit surface of the prism and is imaged on the photoelectric sensor by the lens unit with infinity focusing.

[0011] Further, the light source is an LED light source.

[0012] Furthermore, the light source is implemented by using an LED strip.

[0013] Further, the light source is a single-wavelength LED light source.

[0014] Furthermore, the central wavelength of the light source is between 500 - 600 nm.

[0015] Further, it further includes a light homogenizing unit, which is arranged between the light source and the incident surface of the prism.

[0016] Furthermore, the light homogenizing unit is a light homogenizing sheet, which is fixed on the incident surface of the prism.

[0017] Further, the light homogenizing unit is a light homogenizing film layer, which is coated on the incident surface of the prism.

[0018] Further, the photoelectric sensor is a CMOS image sensor.

[0019] Furthermore, the photoelectric sensor is a area array CMOS image sensor.

[0020] Further, the lens unit is composed of a single lens or multiple lenses.

[0021] Furthermore, the lens unit and the photoelectric sensor are implemented by the camera module of a mobile phone.

[0022] Further, it further includes a filter unit, which is arranged between the exit surface of the prism and the lens unit.

[0023] Furthermore, the filter unit is a filter sheet, which is fixed on the exit surface of the prism.

[0024] Further, the filter unit is a filter film layer, which is coated on the exit surface of the prism.

[0025] Further, the prism is an isosceles prism.

[0026] The present invention also provides an intelligent cup, which is provided with the above-mentioned refractometer for measuring the refractive index of the liquid in the intelligent cup.

[0027] The beneficial technical effects of the present invention:

[0028] By arranging the photoelectric sensor on the image-side focal plane of the lens unit and adopting the infinite focus imaging method for the lens unit, the refractometer of the present invention enables the use of a non-point light source as the light source, so that the size of the light source can share the size of the photoelectric sensor, making the size of the photoelectric sensor very small, and having the advantages of low cost, small volume, large measurement range, and good robustness.

[0029] The refractometer of the present invention uses a matrix CMOS image sensor, which has a lower cost, higher accuracy, lower installation requirements, and can achieve many things that one-dimensional sensors cannot do, such as improving accuracy, enhancing anti-interference ability, adding other measurement functions, etc. Moreover, even if there are bubbles at the contact interface or it is not completely covered, it will not affect the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 It is a schematic structural diagram of an existing reflective electronic sugar refractometer;

[0032] Figure 2 It is a structural diagram of a refractometer disclosed in a previous case;

[0033] Figure 3 For Figure 2 A schematic diagram of equivalenting the photosensitive array to the liquid surface side in

[0034] Figure 4 It is a schematic structural diagram of the refractometer according to Embodiment 1 of the present invention;

[0035] Figure 5 It is a schematic diagram of the imaging principle with the lens unit focused at infinity;

[0036] Figure 6 It is a schematic diagram of equivalenting the photoelectric sensor to the liquid surface side according to Embodiment 1 of the present invention;

[0037] Figure 7 It is a schematic structural diagram of the 6mm light source according to Embodiment 1 of the present invention;

[0038] Figure 8 It is a schematic structural diagram of the 1mm lens unit according to Embodiment 1 of the present invention;

[0039] Figure 9 It is a schematic structural diagram of the 12mm lens unit and the 12mm light source according to Embodiment 1 of the present invention;

[0040] Figure 10 It is the brightness map collected by the photoelectric sensor according to Embodiment 1 of the present invention;

[0041] Figure 11 It is a circuit structure block diagram according to Embodiment 1 of the present invention;

[0042] Figure 12 Schematic structural diagram of the refractometer according to the second embodiment of the present invention;

[0043] Figure 13 Schematic structural diagram of the refractometer according to the third embodiment of the present invention. Detailed implementation manners

[0044] To further illustrate each embodiment, the present invention provides accompanying drawings. These accompanying drawings are part of the disclosure of the present invention, mainly used to illustrate the embodiments, and can be combined with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0045] The present invention will be further described below in conjunction with the accompanying drawings and detailed implementation manners.

[0046] Embodiment 1

[0047] As Figure 4 shown, a refractometer includes a light source 1, a prism 2, a lens unit 3, and a photoelectric sensor 4. The prism 1 has a contact interface 21 in contact with a liquid to be measured 5. The light source 1 has a plurality of (two or more) point light sources arranged in sequence at least in one direction ( Figure 4 the upper left direction in, hereinafter referred to as the first direction) of. The light emitted by the light source 1 enters the prism 2 through the incident surface 22 of the prism 2 and irradiates the contact interface 21. The photoelectric sensor 4 is disposed on the image-side focal plane of the lens unit 3, that is, the lens unit 3 is in an infinitely distant focusing mode. The light reflected from the contact interface 21 exits the prism 2 through the exit surface 23 of the prism 2 and is imaged on the photoelectric sensor 4 by the lens unit 3 using infinitely distant focusing.

[0048] As Figure 5 shown, in optics, parallel light can be converged on the image-side focal plane by a lens (or a lens group). In an ideal case, the convergence point on the image-side focal plane is unique. This convergence point (the intersection of the extension from the optical center of the lens in the direction of this parallel light and the image-side focal plane) is only related to the direction of the light rays and has nothing to do with the position of the light rays. Using this principle, the position and direction of the light rays can be decoupled without setting a slit or a small hole at the light source as disclosed in the previous case to decouple the position and direction of the light rays.

[0049] Therefore, in the present invention, the photoelectric sensor 4 is disposed on the image-side focal plane of the lens unit 3, and this position is also referred to as infinity focusing (parallel light can be considered as emitted from an object at infinity). This focusing method is very common in the small camera modules of mobile phones and can be obtained by using a collimator for focusing, so the cost is very low. Since the infinity focusing method is adopted, the light source 1 can be implemented by a light source having at least a plurality of (two or more) point light sources arranged in sequence in at least one direction. At this time, the field-of-view angle range that the lens unit 3 can image is determined by the focal length f and the lens aperture size, and this field-of-view angle can easily reach 90 degrees, and there are many existing lenses to choose from. In the present invention, we hope to measure as wide a refractive index range as possible. Merely detecting a large field-of-view angle is not enough. We need to ensure that light rays at such a large angle are reflected by the contact interface 21 and incident on the lens unit 3. In the present invention, the angular range of light that the lens unit 3 can receive is jointly determined by the size of the light source 1 (along the first direction) and the size of the lens unit 3 (the size of the light incident aperture). As Figure 6 shown, for more intuitiveness, a geometric equivalent model of reflection is used here to analyze the angle.

[0050] In Figure 6 , the angular range of light that the lens unit 3 can detect is defined by two lines at the edge: the light ray r1 from the uppermost end of the light source 1 to the lowermost end of the light incident aperture of the lens unit 3 and the light ray r2 from the lowermost end of the light source 1 to the uppermost end of the light incident aperture of the lens unit 3.

[0051] It can be seen that this angular range α is determined by three variables: the size of the light source 1, the size of the lens unit 3, and the distance from the light source 1 to the lens unit 3. That is to say, in the case of the same angular range α, the size of the photosensitive array in the prior case is now jointly borne by the size of the light source 1 and the size of the lens unit 3. As can be seen from the dashed line

[0052] Size of the photosensitive array in the prior case = Size of the light source 1 + Size of the lens unit 3

[0053] If the size of the photosensitive array in the prior case needs to be 12 mm, then in the present invention, there are several typical cases in the case of the same angular range α:

[0054] ① In the present invention, only a 6-mm light source 1 + a 6-mm lens unit 3 are needed (the size of the photoelectric sensor 4 is generally close to the size of the lens unit 3). As Figure 7 shown, that is to say, the photoelectric sensor 4 of the present invention only needs half the size of the prior case, thereby reducing the cost and the difficulty of mass production.

[0055] ② More extremely, in the present invention, only a 1-mm lens unit 3 is needed, and the cost and the difficulty of mass production are greatly reduced. At this time, the size of the light source 1 is 11 mm. AsFigure 8 As shown, the size of the light source 1 is very easy to increase, with low cost and no need for high-precision assembly, almost at no cost.

[0056] ③ Additionally, if the size of the lens unit 3 of the present invention is also 12 mm and the light source 1 also has a size of 12 mm, the detectable angle range is nearly doubled compared to the previous case. As Figure 9 shown, at this time, the volume of the overall design does not need to increase because the volume of the prism 2 remains unchanged.

[0057] It can be seen that within the same detectable angle range, the present invention can use almost any size of the photoelectric sensor 4 without affecting the detection angle. Therefore, the present invention can adopt a lens unit 3 and a photoelectric sensor 4 with smaller sizes, greatly reducing the cost. Moreover, the size of the prism 2 also decreases following the light source 1 and the lens unit 3, and the overall volume decreases. At the same time, the measurement range is large and the robustness is good.

[0058] In this specific embodiment, the light source 1 preferably adopts an LED light source, which has the advantages of low cost, small volume, environmental protection, etc. However, it is not limited thereto. In other embodiments, the light source 1 can also be realized by using other existing light sources.

[0059] The light source 1 can be composed of multiple LED lamp beads through the methods of chip mounting or encapsulation, which is already a very mature existing technology and will not be elaborated in detail.

[0060] Preferably, in this embodiment, the light source 1 is realized by using an LED light strip, which is easy to implement, has low cost, and is smaller in volume. Of course, in some embodiments, the light source 1 can also be realized by using other LED light sources, such as an LED surface light source, etc.

[0061] In this specific embodiment, the lens unit 3 can be composed of one lens or multiple lenses, and can specifically be realized by using an existing infinity-focus camera module, which has low cost and high reliability.

[0062] In this embodiment, the photoelectric sensor 4 is preferably a CMOS image sensor. In recent years, with the rise of the mobile phone and intelligent hardware industries, small-sized CMOS image sensors have been mass-applied and iterated for many years, and their photosensitive performance has been very good, with very high resolution and very low cost. However, it is not limited thereto. In some embodiments, the photoelectric sensor 4 can also be realized by using other photoelectric sensors such as a CCD image sensor.

[0063] Furthermore, in this embodiment, the optoelectronic sensor 4 is preferably a area array CMOS image sensor. Compared with a one-dimensional image sensor, it can not only greatly reduce the installation requirements, but also, due to the nature of the two-dimensional array, enable many things that cannot be achieved by a one-dimensional array, such as improving accuracy and anti-interference ability, and increasing the ability to measure other parameters. In addition, even if there are bubbles at the contact interface or it is not fully covered, it will not affect the measurement.

[0064] In this embodiment, the lens unit 3 and the optoelectronic sensor 4 can be implemented using an existing small camera module of a mobile phone, which has low cost, small size, and is easy to implement.

[0065] In this specific embodiment, the prism 2 is made of glass material, but it is not limited thereto. In some embodiments, other transparent materials such as plastic and resin can also be used.

[0066] Preferably, in this embodiment, the prism 2 is an isosceles prism, and more preferably an isosceles right prism. The prism structure is more compact, making the overall structure more miniaturized, but it is not limited thereto.

[0067] Figure 10 The following shows the luminance map collected by the optoelectronic sensor 4 of this embodiment. The horizontal axis corresponds to the first direction of the light source 1. It can be seen that when corresponding to different liquid refractive indices, the dividing line corresponding to the total reflection angle has an obvious shift. By calculating the position of this dividing line, we can calculate the accurate liquid refractive index. The vertical axis corresponds to the direction perpendicular to the first direction of the light source 1. Since there is also light emitted perpendicular to the first direction of the light source 1 and reflected by the contact interface 21 into the optoelectronic sensor 4, there is also a part of the extension on the vertical axis. This part of the extension can better process noise, improve the signal-to-noise ratio, and improve the accuracy of refractive index measurement.

[0068] As Figure 11 As shown, this embodiment further includes a dimming module 100, a processor 200, a power supply module 400, and an interaction module 300. The control end of the dimming module 100 is connected to the control output end of the processor 200. The output end of the dimming module 100 is connected to the light source 1 for driving the light source 1 to emit light. The output end of the optoelectronic sensor 4 is connected to the input end of the processor 200. The processor 200 is connected to the interaction module 300. The power supply module 400 supplies power to the entire refractometer. The power supply module 400 can be externally powered or battery-powered. The battery can be a rechargeable battery or a non-rechargeable battery. The interaction module 300 can include a touch switch and a display screen, etc.

[0069] Embodiment Two

[0070] As Figure 12As shown in the figure, the difference between this embodiment and the first embodiment is that this embodiment further includes a light homogenizing unit 6, which is arranged between the light source 1 and the incident surface of the prism 2. The light homogenizing unit 6 is used to make the light in each direction emitted by the light source 1 relatively uniform. Therefore, the image formed by the photoelectric sensor 4 can also be relatively uniform, thereby improving the measurement accuracy.

[0071] In this specific embodiment, the light homogenizing unit 6 is a light homogenizing sheet, which is fixedly arranged on the incident surface 22 of the prism 2, making the structure more compact and small-sized, and easy to assemble. However, it is not limited to this. In other embodiments, the light homogenizing sheet can also be fixed on other components such as the light source 1.

[0072] Of course, in other embodiments, the light homogenizing unit 6 can also be a light homogenizing film layer, which is coated on the incident surface 22 of the prism 2, making the number of components less, the whole more compact, and the assembly more convenient.

[0073] Embodiment Three

[0074] As Figure 13 shown in the figure, the difference between this embodiment and the second embodiment is that in this embodiment, a filter unit 7 is further included. The filter unit 7 is arranged between the exit surface 23 of the prism 2 and the lens unit 3. Correspondingly, the light source 1 is a single-wavelength LED light source. The filter unit 7 is used to allow the light of the light source 1 to enter the lens unit 3 while blocking the light of other wavelengths, such as sunlight, lamp light, etc. Because this kind of light is not reflected by the contact interface 21 and will interfere with the measurement, thereby improving the measurement accuracy. And by using a single-wavelength LED light source, the lens unit 3 does not need to consider the chromatic aberration requirements, thus greatly reducing the design difficulty.

[0075] The filter unit 7 needs to consider the change of the spectral cut-off wavelength within the entire measurement angle and temperature range so that the light of the light source 1 can pass through the filter unit 7.

[0076] The wavelength of the light source 1 needs to be compatible with the CMOS image sensor, usually ranging from 300nm - 1000nm, such as 400 - 500nm, 500nm - 600nm, 600nm - 700nm, 700nm - 800nm. Some of the existing CMOS image sensors on the market are color ones, and they have higher resolution and sensitivity for the G channel. Therefore, in this embodiment, the wavelength of the light source 1 is preferably 500nm - 600nm to respond to the G channel.

[0077] In this specific embodiment, the filter unit 7 is a filter sheet, which is fixed on the exit surface 23 of the prism 2, making the structure more compact and small-sized, and easy to assemble. However, it is not limited to this. In other embodiments, the filter sheet can also be fixed on other components such as the lens unit 3.

[0078] Of course, in other embodiments, the light filtering unit 7 may also be a light filtering film layer coated on the exit surface 23 of the prism 2, which results in fewer components, a more compact overall structure, and simpler assembly.

[0079] Embodiment 4

[0080] The present invention also provides an intelligent cup provided with the above-mentioned refractometer for measuring the refractive index of the liquid in the intelligent cup. In this embodiment, the intelligent cup can be an intelligent water cup, an intelligent beverage cup, etc. The intelligent beverage cup includes an intelligent coffee cup, an intelligent juice cup, etc.

[0081] Embodiment 5

[0082] The present invention also provides an intelligent urinal provided with the above-mentioned refractometer for measuring the refractive index of the urine in the intelligent urinal.

[0083] Embodiment 6

[0084] The present invention also provides an intelligent ultra-small handheld saccharimeter provided with the above-mentioned refractometer for measuring the sugar content of a liquid through the refractometer.

[0085] Embodiment 7

[0086] The present invention also provides an intelligent animal urine detector (such as a mat) provided with the above-mentioned refractometer for measuring the refractive index of animal urine through the refractometer.

[0087] By arranging the photoelectric sensor on the image-side focal plane of the lens unit and using the lens unit for infinity-focus imaging, the refractometer of the present invention enables the use of a non-point light source as the light source. Thus, the size of the light source is used to share the size of the photoelectric sensor, making the size of the photoelectric sensor very small, and having the advantages of low cost, small volume, large measurement range, and good robustness.

[0088] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes can be made to the present invention in terms of form and details without departing from the spirit and scope of the present invention defined by the appended claims, and all such changes are within the protection scope of the present invention.

Claims

1. A refractometer, characterized in that: It includes a light source, a prism, a lens unit and a photoelectric sensor. The prism has a contact interface in contact with the liquid to be measured. The light source has a plurality of point light sources arranged in sequence at least in one direction. The light source is configured such that the light emitted by the light source enters the prism through the incident surface of the prism and irradiates the contact interface. The photoelectric sensor is disposed on the image-side focal plane of the lens unit. The light reflected from the contact interface exits the prism through the exit surface of the prism and is imaged on the photoelectric sensor by the lens unit with infinity focus; the photoelectric sensor is a area array CMOS image sensor; It further includes a light homogenizing unit, which is disposed between the light source and the incident surface of the prism to make the image formed by the photoelectric sensor relatively uniform.

2. The refractometer according to claim 1, characterized in that: The light source is an LED light source.

3. The refractometer according to claim 2, characterized in that: The light source is realized by using an LED strip.

4. The refractometer according to claim 2 or 3, characterized in that: The light source is a single-wavelength LED light source.

5. The refractometer according to claim 4, characterized in that: The central wavelength of the light source is between 500 - 600 nm.

6. The refractometer according to claim 1, characterized in that: The light homogenizing unit is a light homogenizing sheet, which is fixed on the incident surface of the prism.

7. The refractometer according to claim 1, characterized in that: The light homogenizing unit is a light homogenizing film layer, which is coated on the incident surface of the prism.

8. The refractometer according to claim 1, characterized in that: The lens unit is composed of a single lens or multiple lenses.

9. The refractometer according to claim 8, characterized in that: The lens unit and the photoelectric sensor are realized by the camera module of a mobile phone.

10. The refractometer according to claim 1, characterized in that: It further includes a filter unit, which is disposed between the exit surface of the prism and the lens unit.

11. The refractometer according to claim 10, characterized in that: The filter unit is a filter sheet, which is fixed on the exit surface of the prism.

12. The refractometer according to claim 10, characterized in that: The filter unit is a filter film layer, which is coated on the exit surface of the prism.

13. The refractometer according to claim 1, characterized in that: The prism is an isosceles prism.

14. An intelligent cup, characterized in that: There is a refractometer according to any one of claims 1 - 13, which is used to measure the refractive index of the liquid in the intelligent cup.

Images