JPS61253447A - Method and apparatus for detecting liquid purity of frying oil or the like - Google Patents

Abstract

PURPOSE:To detect the purity of a liquid properly in an accurate and sample manner, by propagating light through an optical fiber with the liquid to be detected attached to one end face of the optical fiber. CONSTITUTION:Water is attached to the light emission end 1a of an optical fiber 1 within a transverse hole 11a, light is propagated through the fiber 1 under the normal temperature and the current computation output level is inputted into a memory circuit 27 to be a reference signal for correction. Then, a new oil such as bean oil is attached sequentially to the light emission end 1a and the level of a signal from a computation circuit 23 is memorized into the circuit 27. On the other hand, the memorization of the signal for correction and the signal level corresponding to the refractive index of each drying oil is done with a changeover switch 31. Then, to check the deterioration in the frying oil, the switch 31 is changed to match the type of the frying oil, the frying oil is attached to the light emission end 1a to scatter the light propagating through the fiber 1 and the light is received with optical fibers 9a-9e. The propagated light received from the fiber is passed through photoconductive cells 17a-17e, an amplification circuit 29 and a detection circuit 21 and the output thereof is outputted to the circuit 23, which outputs signals different in the level to a comparator or circuit 25 and 27. The signal and the reference signal are compared 25 and displayed 35.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting the degree of purity of liquid such as fried oil, and a detection device suitable for the detection.

[Conventional technology]

Traditionally, at fast food shops that sell snack fried foods such as french fries and fried chicken, the quantity of fried food is large and the frying oil is kept in a heated state for a long time, resulting in significant deterioration of the frying oil and the need to replenish and replace the frying oil frequently. It is necessary to do it.

However, there are few methods to easily check the degree of deterioration, and currently the judgment relies on intuition, which makes it impossible to achieve a uniform taste of fried foods and results in different tastes at each store, which is undesirable for business purposes. It was bringing about.

Additionally, there was a problem in that the amount of frying oil used differed between each two stores, making it impossible to ensure consistent material management.

The present inventor discovered that as the purity of the liquid used as frying oil continues to decline, double bonds decrease, long chain acids are decomposed and the molecular structure changes to a short chain, and the molecular weight increases, causing an increase in viscosity. focused on the phenomenon that the refractive index of fried oil increases as a result, and discovered that the degree of purity of liquids such as fried oil can be detected using an optical method without the need for troublesome work and with accurate and simple operations.

[Problem that the invention seeks to solve]

The present invention has been made to solve these conventional drawbacks, and provides a method and device for detecting the purity of a liquid such as fried oil, which can accurately and easily detect the purity of a liquid as appropriate.

[Means for solving problems]

In order to solve such problems, the liquid purity detection method of the present invention propagates light through the optical fiber with the liquid to be detected attached to one end face of the optical fiber, and detects the light from the optical fiber. Diffuse the light.

This scattered light is converted into an electric signal according to the degree of spread of the light, and the electric signal based on the degree of light scattering when a standard solution is applied to the light output end face in advance is used as a standard signal. The level difference between the standard signal and the electric signal based on the liquid to be detected is compared, and the comparison result is displayed on a display means to detect the liquid purity.

[For production]

Generally, light is emitted from the output end of an optical fiber in a spread-out manner, and the degree of spread is determined by the so-called aperture (number).
Its value changes depending on the relative refractive index difference between the core and the material in contact with this end surface. On the other hand, the refractive index of frying oil increases as its deterioration progresses.

When oil or fat is attached to the light output end of an optical fiber, the degree of aperture changes depending on the degree of deterioration.

Therefore, by converting the opening degree when new oil is applied to an electrical signal and using it as a reference value, and comparing this with the electrical signal when oil is applied to the light output end of the optical fiber, the degree of deterioration can be determined. .

〔Example〕

The present invention will be explained in detail below.

FIG. 1 shows an embodiment of a detection device used in the method for detecting the purity of liquid such as fried oil according to the present invention.

In the figure, a light emitting diode 3 as a light emitting element that propagates light is connected to one end (light input end) of an optical fiber 1, and an oscillation a7 is transmitted to the light emitting diode 3 via an amplifier 5. Connected.

An oscillation signal from an oscillator 7 causes the light emitting diode 3 to emit light intermittently.

In addition to optical fiber 1! A plurality of optical fibers 9a to 9e with one end (light input end) facing the light output end 1a of the optical fiber 1 are arranged in a line at positions equally spaced from (light output end) la.

Each of the optical fibers 9a to 9e has a central optical fiber 9C.
Align the center axis of the optical fiber 1 with the left and right optical fibers 9a, 9b, 9d, and 9e.

The light emitting end 1d of the optical fiber 1 is located on an arc centered on the light emitting end 1d.

These optical fibers 1.9a to 9θ are of conventionally known type, for example, multimode step type.

A fixing member 11 having a blind horizontal hole 11a has a horizontal hole 1 therein.
They are supported in such a way that they face each other in the vertical direction with 1a in between.

As shown in FIG. 2, fried oil can be applied to the light emitting end 1a of the optical fiber 1 through a window 17 provided in the front panel 15 of the case 13 housing the two devices.

Various locations of optical fibers 9a to 9e! At the (light output end), EDS photoconductive cells 173 to 17e, each serving as a light receiving element that receives propagated light and converts it into an electric signal, are arranged facing each other. The photoconductive cells 173-17e may be photodiodes or phototransistors.

A synchronous detector 21 is connected to each photoconductive cell 17a-17e via an amplifier 19, and the photoconductive cells 1, 7a-1
The output voltages of the detectors 7e are separately detected by the detector 21 in synchronization with the oscillation cycle of the oscillator 7, and each detection output is output to the arithmetic circuit 23. In addition, each amplifier 19 and each detector 21 connected to each photoconductive cell 172-17e are shown together as one.

This arithmetic circuit 23 digitally adds the detection outputs based on the signals from the two photoconductive cells 17a to 17e, and outputs the result to a comparison circuit 25 and a memory circuit 27 (words).

That is, in the arithmetic circuit 23, the photoconductive cells 17b to 17 are determined based on the output based only on the detection signal from the photoconductive cell 17C.
The output based on the detection signal from the photoconductive cells 15a to 15e is larger than that based on the detection signal from the photoconductive cells 15a to 15e. In other words, a signal with a level corresponding to the scattering area of the light from the optical fiber 1 is output.

The memory circuit 27 stores the signals obtained from the arithmetic circuit 23 as standard signals when new fried oil is attached to the light output end 1a of the optical fiber 1 according to the type of fried oil expected to be detected. It has a storage area for storage, and selectively outputs the storage contents to the comparison circuit 25.

Furthermore, the memory circuit 27 has a function of calculating the usage limit level of each frying oil from the stored standard signals and storing each limit value, and outputs each limit value to a drive circuit 33 described later.

Furthermore, the memory circuit 27 is also connected to a correction circuit 29, and this correction circuit 29 is connected to the light output end 1a of the optical fiber 1.
Based on the signal level input to the memory circuit 27 when water is attached to the oil, the standard signals corresponding to each type of oil are slid/amplified in parallel to standard values at relatively the same intervals. It is corrected and stored in the memory circuit 27.

The reason why such correction is necessary is to ensure accurate detection even if there are variations in each component or changes over time. Although it is difficult, it is possible to use a generally known one.

This correction and the selection of the memory contents to be output to the comparison circuit 25 are as follows:
This is done by a changeover switch 31 arranged on the front panel 15 of the case 13 in FIG.

The comparison circuit 25 compares the output signal from the arithmetic circuit 23 with the level (voltage) of the standard signal from the memory circuit 27,
An output corresponding to the difference between them is output to the drive circuit 33.

A display device 35 and a buzzer 37 are connected to this drive circuit 33.

The display device 35 is as shown in FIG.

As a display section, a plurality of light emitting bodies 2 are used, for example, three green light emitting diodes 39a to 39c and two red light emitting diodes 39.
d and 39e are arranged in a row in the left-right direction on the entire surface panel 15. Of course, the display may be performed using a 7-segment LED or an analog meter instead of the 2 light-emitting diodes.

These five light emitting diodes 39a to 39e.

The light is turned on sequentially from the left end in accordance with the output signal from the comparison of the comparison circuit 25, and the output from the comparison circuit 25 increases from the left end light emitting diode 39a to the right end light emitting diode 39e, causing deterioration of the frying oil. This shows that progress is being made.

Moreover, when the drive circuit 33 receives a signal higher than the limit value signal from the memory circuit 27 as a reference level, the two red light emitting diodes 39d and 39e on the right side are activated.
The buzzer 35 is configured to operate.

Therefore, the red light emitting diodes 39d, 39e and the buzzer 3
5 is activated, it indicates that the frying oil has deteriorated and the liquid purity exceeds the usage limit, and that it needs to be replaced.

Further, the front panel 15 of the case 13 is equipped with a test bushing switch 41, and when this is turned on, the output of the arithmetic circuit 23 is input to the drive circuit 33 via the monitor circuit 43, and the display device 35 is activated. You can check whether the device is functioning properly.

Next, a first example of the method for detecting the purity of liquid such as fried oil according to the present invention will be described using a detection device having such a configuration.

First, water is applied to the light output end 1a of the optical fiber 1 in the side hole 11a through the window 17 of the case 13.

Light is propagated through the optical fiber 1 at room temperature, and the calculated output level at that time is input to the memory circuit 27 and used as a reference signal for correction.

Next, new oil such as soybean oil, sesame oil, rapeseed oil, palm oil, etc. is sequentially applied to the light emitting end 1a of the optical fiber 1.

The level of the calculation signal obtained from the calculation circuit 23 is stored in the memory circuit 27.

The storage of correction signals and signal levels corresponding to the refractive index of fresh oil for each frying oil is performed sequentially by switching the changeover switch 31.

In general, the refractive index of the core of the optical fiber 1 using quartz is 1.5. That of cladding is 1% smaller at 1.48
The refractive index of new oil is as follows.

Soybean oil: 1.471-1.475 (25℃) Sesame oil: 1.471-1.472 (25℃) Rapeseed oil: 1
．． 470-1.474 (25℃) Balm oil: 1.44
9 to 1.455 (50°C) Next, when it becomes necessary to check the deterioration of the fried oil, change the changeover switch 31 according to the type of fried oil to be detected, and connect the no-fried fried oil to the light output end 1a of the optical fiber 1. The light propagating through the optical fiber 1 at room temperature is scattered at the light output end, and the scattered light is received by the optical fibers 9a to 9e.

Prior to this operation, water may be applied to the light output end 1a of the optical fiber 1, and the reference signal in the memory circuit 27 may be corrected as described above.

Then, the propagating light from one of the optical fibers 98 to 9e that receives the light is converted into an electrical signal by the photoconductive cells 17a to 17e, amplified and detected by the amplifier circuit 19 and the detection circuit 21, and its output is calculated. It is output to the circuit 23.

The arithmetic circuit 23 outputs signals having different levels to the comparison circuit 25 and the memory circuit 27 depending on the detection output from any of the optical fibers 9a to 9e.

In this case, as shown in FIG. 3, at the light output end 1a of the optical fiber 1, if the difference in refractive index between the core 1b and the substance in contact with the core 1b is large, the output angle of the diffused light will be widened, and the difference in refractive index will be small. Therefore, if the angle of light emission in the case of new oil is as shown by the solid line, it will become wider as shown in the broken line when fried oil with advanced deterioration is attached.

Therefore, the output signal from the arithmetic circuit 23 is larger for deteriorated fried oil than for new oil.

The comparison circuit 25 compares the signal level based on the detected fried oil with the standard value from the memory circuit 27.

A signal corresponding to the difference is output to the display device 35 via the drive circuit 33.

In the display device 35, five light emitting diodes 392
- 39e are continuously lit in accordance with the above output.

Therefore, depending on whether any of the five light emitting diodes 39a to 39e is lit, the degree of deterioration of the frying oil can be known at a glance.

In particular, as the liquid purity continues to decline, the difference between the signal level at the time of detection and the standard signal level increases, so if a signal larger than the limit value signal from the memory circuit 27 is input from the comparator circuit 25 as a reference.

Turn on red light emitting diodes 39d and 39e and buzzer 3
7 is activated and the limit value of the frying oil is displayed, which indicates that the frying oil must be replaced.

Note that the number of optical fibers 9a to 9e that receive the scattered light from the optical fiber 1 in the above-mentioned embodiment is arbitrary;
Although it is possible to arrange a plurality of optical fibers concentrically, from the viewpoint of simplifying the configuration, it is preferable to arrange them in a small number of rows. ~9e if they are selected at equal intervals.

More accurate detection becomes possible.

Further, as light receiving means other than the optical fibers 9a to 9e, a plurality of photodiodes or the like may be arranged to directly receive and convert the light from the optical fiber 1.

Furthermore, in the above-described embodiment, the diffused area of the light from the optical fiber 3 is detected based on the signals from the optical fibers 9a to 9e that are receiving light, but it is detected based on the signals from the optical fibers 9a to 9e that are not receiving light. Alternatively, the light scattering region may be detected by determining the 0N10FF of the light received by the optical fibers 9a to 9e, that is, the end of the light scattering region. These can be arbitrarily selected depending on the configuration of the arithmetic circuit 23. FIG. 4 shows a second example of the present invention.

That is, as in FIG. 1, the tip of an optical fiber 45 whose light input end is connected to the light emitting diode 3 connected to the amplifier circuit 5 is cut obliquely, and another light source is placed parallel to this optical fiber 45. One end of the fiber 47 is also cut obliquely, and the cut surfaces of each optical fiber 45 and 47 are oriented to face each other.

A photoconductive cell 49 is connected to the light output end of an optical fiber 47, and is connected to a detector 53 via an amplifier 51.

In this configuration, the scattered light from the light output end 45a of one optical fiber 45 is transferred to the light input end 47a of another optical fiber 47.
The light propagated through the optical fiber 47 is converted into an electrical signal and detected.

That is, in the embodiment of FIG. 1 described above, the optical fiber 3
The purpose of this configuration is to obtain a signal with a level corresponding to the change in the light scattering area and compare it with a standard value.
An output corresponding to the amount of light received in a constant light receiving area in the diffused region of the light from the optical fiber 45 is output to the comparison circuit 25 and the memory circuit 27, and when fried oil is attached to the light output end 45a of the optical fiber 45. This takes advantage of the fact that the amount of received light changes with changes in the light output angle.

Therefore, the number of light-receiving optical fibers 47 is not limited to one, but may be multiple, as long as they form a certain light-receiving area that receives the scattered light from the optical fibers 45.

Further, according to the present invention, a third detection method can also be implemented by combining the devices shown in FIG. 3 (FIG. 1) and FIG. 4 described above.

A fourth light emitting element is connected in place of each photoconductive cell 17a to 17e connected to each optical fiber 9a to 9e in FIG.
A photoconductive cell is placed in place of the light emitting diode 3 connected to the optical fiber 1 shown in FIG. While attaching the oil and fat to be detected (in the example, the light output end), a plurality of lights with different incident angles are irradiated from the optical fibers 9a to 9e to the attached surface, and the standard value when new oil is attached and the value when the detected fried oil is attached. This is to compare the propagation light of .

That is, since the aperture of the optical fiber 1 changes depending on the refractive index of the oil attached to the core 1b of the optical fiber 1,
This method takes advantage of the fact that the amount of light propagating through the optical fiber 1 also changes due to changes in the refractive index of oils and fats with respect to irradiated light.

As described above, in the present invention, the amount of light passing through the oil and fat attached to the end face of the optical fiber may be used for detection by comparing it with a standard value.

By the way, the present invention described above is suitable for detecting liquid purity, such as the sugar content to measure the content of sugar dissolved in the liquid, natural fruit juice content in juice, etc., in addition to liquid purity such as deterioration of fried oil. do.

Furthermore, it is possible to detect the purity of liquids having various refractive indexes depending on the refractive index of the core that constitutes the optical fiber.

〔Effect of the invention〕

As explained above, the method for detecting the purity of liquid such as fried oil of the present invention accurately and easily measures the purity of liquid such as fried oil.

It has the advantage of being able to detect at any time or at any time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a device used in the method for detecting the purity of liquids such as fried oil according to the present invention, FIG. 2 is a front view showing the detection device shown in FIG. 1 housed in a case, and FIG. FIG. 4 is a block diagram showing another embodiment of the present invention. 1.9a to 9e, 45.47...Optical fiber 3...Light emitting element (light emitting diode) 7...
...Oscillator 13 ... Cases 17a to 17e, 49 ... Light receiving element (photoconductive cell) 21
．． 53... Detector 23... Arithmetic circuit 25... Comparison circuit 27... Memory circuit 31... Changeover switch 33... ... Drive circuit 35 ... Display circuit 37 ... Buzzer 39a to 39e ... Light emitting diode Patent applicant Shikata 1) Miyu Figure 2 Figure 3

Claims (8)

[Claims] (1) With the liquid to be detected attached to the light output end face of the optical fiber, light is propagated from the light input end of the optical fiber to scatter the light from the light output end, and the scattered light is A standard liquid is attached to the light emitting end face in advance and an electric signal based on the degree of light scattering is used as a standard signal, and an electric signal based on this standard signal and the detected liquid is converted into an electric signal according to the degree of scattering. A method for detecting the purity of a liquid such as fried oil, characterized by comparing the level difference with a signal and displaying the comparison result on a display means. (2) A method for detecting the purity of a liquid such as fried oil according to claim 1, in which an electric signal corresponding to the degree of light scattering is obtained based on a change in the light scattering area. (3) A method for detecting the purity of a liquid such as fried oil according to claim 1, in which an electric signal corresponding to the degree of light scattering is obtained based on a change in the amount of light received in a certain area. (4) With the liquid to be detected attached to the light input end face of the optical fiber, light is irradiated toward the light input end face, and the light propagating through the optical fiber is adjusted to the amount of light at the light output end of the optical fiber. The electrical signal obtained when a standard solution is attached to the light input end surface in advance is used as a standard signal, and the level difference between this standard signal and the electrical signal based on the detected liquid is compared. , A method for detecting the purity of a liquid such as fried oil, characterized in that the comparison result is displayed on a display means. (5) The method for detecting the purity of a liquid such as fried oil according to claim 4, wherein the light incident end face of the optical fiber is irradiated with light at a plurality of incident angles. (6) an optical fiber whose light emitting end face is a part to which a liquid to be detected is attached; a light emitting means connected to the light input end of the optical fiber for propagating light to the optical fiber; and a light receiving surface facing the light emitting end face. a light receiving and converting means arranged to receive an electrical signal according to the degree of light scattering; and a comparing means that compares the electrical signal from the light receiving and converting means with a preset standard signal and outputs a signal corresponding to the difference. , and display means for displaying the output from the comparison means. (7) a plurality of light-receiving side optical fibers, each of which is arranged in at least one line facing the light-emitting end face of the optical fiber connected to the light-emitting element at equal intervals, and detects a light scattering area thereof; Claim 1 comprising a conversion element that converts the propagating light from these light-receiving optical fibers into an electrical signal, and an arithmetic circuit that outputs a signal according to the light scattering area based on the output from each conversion element. Liquid purity detection device for fried oil, etc., as described in item 4. (8) A light receiving side optical fiber which is arranged opposite to the light emitting end face of the optical fiber connected to the light emitting element and receives light in a certain area, and a light receiving side optical fiber which is connected to the light emitting element, 5. The device for detecting the purity of a liquid such as fried oil according to claim 4, comprising a conversion element for converting into a corresponding electric signal.