JP2024041242A - Distance measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measurement device capable of improving distance measurement accuracy.

SOLUTION: A distance measurement device (1) includes: a light source (4) configured to emit light towards an object (10); an optical sensor (3) configured to receive reflected light from the object; and a distance detection unit (52) configured to calculate distance to the object based on a light detection value output from the optical sensor and the following calculation formula. Y=aX^b, where Y is distance; X is the light detection value; and a and b are coefficients.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to a distance measuring device.

2. Description of the Related Art Distance measuring devices that measure distances to objects have been known. For example, a water level gauge is a type of distance measuring device. In the case of a water level gauge, the target object is the liquid level, and the height of the liquid level can be measured by measuring the distance to the liquid level. Note that, as a conventional water level gauge, for example, a so-called float type one is known (for example, Patent Document 1).

Utility Model Publication No. 4-24028

Recently, there has been a demand for improved water level measurement accuracy in water level gauges.

In view of the above situation, an object of the present disclosure is to provide a distance measuring device that can improve distance measurement accuracy.

For example, an exemplary distance measuring device of the present disclosure includes:
a light source configured to emit light toward an object;
an optical sensor configured to receive reflected light from the target object;
The apparatus includes a distance detection section configured to calculate a distance to the target object based on the light detection value output from the optical sensor and the calculation formula below.
Y=a・X ^b
However, Y is distance, X is light detection value, a and b are coefficients

According to the distance measuring device of the present disclosure, distance measurement accuracy can be improved.

FIG. 1 is a diagram showing an example of the configuration of a distance measuring device. FIG. 2 is a schematic diagram showing a distance measuring device and a target object. FIG. 3 is a diagram showing an example of the configuration of a color sensor. FIG. 4 is a diagram showing an example of the results of the experiment. FIG. 5 is a diagram showing the result of plotting the actual distance and estimated distance in FIG. 4. FIG. 6 is a diagram showing the configuration of a distance measuring device according to a modified example. FIG. 7 is a table listing examples of measurement environment variation factors and examples of variation detection means. FIG. 8 is a flowchart illustrating an example of measurement environment change detection processing. FIG. 9 is a diagram showing a first configuration example of the calibration section. FIG. 10 is a diagram showing a second configuration example of the calibration section. FIG. 11 is a diagram showing a third configuration example of the calibration section. FIG. 12 is a schematic diagram showing an example of the configuration of a toilet tank.

Exemplary embodiments will be described below with reference to the drawings.

<1. Configuration of distance measuring device>
FIG. 1 is a diagram showing an example of the configuration of a distance measuring device. The distance measuring device 1 shown in FIG. 1 includes a substrate 2, a color sensor 3, a white LED 4, a control section 5, a switch SW, and a resistor R. The color sensor 3, white LED 4, switch SW, and resistor R are mounted on the substrate 2. The control unit 5 is, for example, a microcomputer.

The white LED (an example of a light source) 4 is a chip LED that emits white light. The switch SW and the resistor R are arranged on a path through which current flows to the white LED 4 by the power supply voltage VCC. The switch SW is turned on and off by the control unit 5. By turning the switch SW on and off, the white LED 4 can be turned on and off. The resistor R limits the current flowing through the white LED 4 and adjusts the amount of white light.

The color sensor (an example of an optical sensor) 3 is a sensor IC capable of detecting color components of light. Specifically, the color components are an R component (red component), a G component (green component), and a B component (blue component). When the switch SW is turned on by the control unit 5, the white LED 4 emits white light. As shown in FIG. 2, the white LED 4 irradiates the object 10 with white light. The color sensor 3 receives the light reflected by the object 10 and detects the color component. The color sensor 3 outputs the detected color components to the control unit 5 as digital data. The digital data output by the color sensor 3 is, for example, 16-bit data.

The control unit 5 includes a bit conversion unit 51, a distance detection unit 52, an environmental change detection unit 53, a notification unit 54, and a calibration unit 55.

The bit conversion unit 51 converts the digital data output from the color sensor 3 into, for example, 8-bit digital data.

The distance detection unit 52 calculates the distance L between the object 100 and the color sensor 3 (FIG. 2) based on the bit-converted color component detection value and the calculation formula 5A for calculating the distance. The calculation formula 5A is stored in advance in the control section 5 (distance detection section 52). The details of calculation formula 5A will be described later.

The environmental change detection unit 53 detects a change in the distance measurement environment. The notification unit 54 notifies the user based on the detection result of the environmental change detection unit 53. Details of the environmental change detection section 53 and the notification section 54 will be described later.

The calibration unit 55 updates the calculation formula 5A, and the details will be described later.

Note that, as described later, the color sensor 3 can also detect an IR (infrared) component in addition to the RGB components.

<2. Color sensor configuration>
FIG. 3 is a diagram showing an example of the configuration of the color sensor 3. As shown in FIG. The color sensor 3 shown in FIG. 3 includes light receiving elements 31A, 31B, 31C, and 31D, ADCs (AD converters) 32A, 32B, and 32C, a logic circuit 33, an infrared cutoff filter 34, and a red light transmission filter 35A. It has a green light transmission filter 35B, a blue light transmission filter 35C, an infrared transmission filter 35D, and a switch 36.

The light receiving element 31A generates an analog current signal according to the amount of red light incident through the infrared cutoff filter 34 and the red light transmission filter 35A. That is, the light receiving element 31A detects the R component (red component) of the input light.

The light receiving element 31B generates an analog current signal according to the amount of green light incident through the infrared cutoff filter 34 and the green light transmission filter 35B. That is, the light receiving element 31B detects the G component (green component) of the input light.

The light receiving element 31C generates an analog current signal according to the amount of blue light incident through the infrared cutoff filter 34 and the blue light transmission filter 35C. That is, the light receiving element 31C detects the B component (blue component) of the input light.

The light receiving element 31D generates an analog current signal according to the amount of infrared light incident through the infrared transmission filter 35D. That is, the light receiving element 31D detects the IR component (infrared component) of the input light.

As each of the above-mentioned light receiving elements 31A, 31B, 31C, and 31D, a photodiode, a phototransistor, or the like can be suitably used.

ADCs 32A and 32B convert the analog current signals from light receiving elements 31A and 31B into, for example, 16-bit digital data and output the converted data. ADC 32C also converts the analog current signal from either light receiving element 31C or 31D into digital data in response to switching of switch 36 and outputs the converted data.

The infrared blocking filter 34 blocks IR components contained in input light on the upstream side of each of the red light transmitting filter 35A, the green light transmitting filter 35B, and the blue light transmitting filter 35C. By providing such an infrared cutoff filter 34, RGB components can be detected with high accuracy.

The logic circuit 33 has an ADC logic function (=ADC time division control function) and an I ² C interface function (=communication function of data signal SDA and clock signal SCL). The logic circuit 33 sends digital data as RGB component detection signals and IR component detection signals output from the ADCs 32A, 32B, and 32C to the control unit 5 through I ² C communication.

<3. Calculation formula＞
Since the output value of the color sensor 3 (optical sensor) cannot be directly used as the distance, a calculation formula for converting the sensor output value into a distance is required. Here, the inventor conducted an experiment in which the output value of the color sensor 3 was obtained while changing the distance between the color sensor 3 and the object. FIG. 4 shows an example of the results of the experiment. Note that FIG. 4 illustrates the R component detection value among the detection values of the RGB components of the color sensor 3.

In FIG. 4, the vertical axis indicates the distance between the color sensor 3 and the object, and the horizontal axis indicates the output value (R component detection value) of the color sensor 3. As shown by the broken line in FIG. 4, the output value of the color sensor 3 was acquired while changing the distance from a predetermined Lmin to a predetermined L1 in steps of a predetermined distance. That is, the broken line in FIG. 4 is a line connecting the points of the combination of the actual distance (actual distance value) and the output value of the color sensor 3. Note that the output value of the color sensor 3 is assumed to be 16 bits. The longer the distance, the smaller the output value of the color sensor 3 becomes.

In response to the results of the experiment, the inventor of the present application conducted intensive studies and found the following equation (1) as a mathematical equation for deriving the distance between the object and the sensor from the sensor output value.
Y=a・X ^b (1)
However, Y is distance, X is sensor output value, a and b are coefficients

If there are two points (X, Y) where the sensor output value and the actual distance are combined, the coefficients a and b in equation (1) can be determined exactly. Specifically, the coefficients a and b can be determined by substituting the two points (X1, Y1) (X2, Y2) into the equation (1) and solving the simultaneous equations by taking the logarithm of both sides of the equation.

In the example of FIG. 4, two points P1 and P2 where (distance, R component detection value) is (L1, R1) and (L2, R2) are selected, and coefficients a and b of equation (1) are derived. The solid line in FIG. 4 shows the result of estimating the distance from the sensor output value using Equation (1) determined in this way. In Figure 4, when the distance is less than L3 (<L2), the estimated distance value becomes slightly higher than the actual value and deviates from it, but in sections where the distance is longer than L3, the estimated distance value does not match the actual value. I can see that If the measurement distance range actually used is included in the section where the distance is longer than L3, it is possible to estimate the distance with high accuracy. Therefore, if the distance measurement range to be used is determined, it is desirable to select two points included in the distance measurement range to determine equation (1).

FIG. 5 shows the result of plotting the actual distance and estimated distance in FIG. 4. In FIG. 5, the estimation accuracy is best when the plot does not deviate from a straight line connecting points where the actual distance and the estimated distance have the same value. As shown in FIG. 5, when the distance is L3 or less, the estimated value of the distance exceeds the actual value, but in a section where the distance is longer than L3, the distance can be estimated with high accuracy.

In the distance measuring device 1 (FIG. 1) of this embodiment, the distance detection section 52 of the control section 5 has the above equation (1) as the calculation equation 5A. The distance detection section 52 can calculate the distance using equation (1) based on the output value of the color sensor 3, that is, the output of the bit conversion section 51. Note that if the bit converter 51 is not provided, the output value of the color sensor 3 may be directly used to calculate the distance.

The distance detection unit 52 can have equation (1) for at least one of the R component detection value, the G component detection value, and the B component detection value as the calculation formula 5A. That is, it is possible to have only the formula (1) for one component among the RGB components, or the formula (1) for each of multiple components among the RGB components (for example, the formula (1) for the R component and the formula (1) for the G component). (1) regarding the components).

When the distance detection unit 52 has a plurality of equations (1), the optimum equation selected by calibration may be selected to calculate the distance, as will be described later. Alternatively, for example, an average value of distances calculated using a plurality of formulas may be used as the distance measurement value. Further, the color sensor 3 may be configured to detect only the color components used in the calculation formula 5A. That is, the color sensor 3 does not necessarily need to detect three color components.

<4. Configuration using illuminance sensor>
FIG. 6 is a diagram showing the configuration of a distance measuring device 1 according to a modification of this embodiment. In the configuration shown in FIG. 6, an illuminance sensor 6 is provided in place of the color sensor 3. The illuminance sensor 6 detects the illuminance of light reflected by the object 10. In this case, the distance detection unit 52 has equation (1) with the sensor output value X as the illuminance as the calculation equation 5A. Thereby, the distance detection unit 52 can calculate the distance using equation (1) based on the output value of the illumination sensor 6.

<5. Effects of measurement environment changes>
In this way, according to the distance measuring device 1 according to the present embodiment, by calculating the distance using equation (1), highly accurate distance measurement is possible. However, as time passes, it is assumed that the measurement environment changes from the measurement environment when the coefficients in equation (1) were determined. Factors that cause changes in the measurement environment include, for example, fading or discoloration of the object, changes in the reflectance of the object, fluctuations in the amount of light from the white LED 4, and intrusion of external environmental light. In this case, if the distance is calculated while using the current coefficient equation (1), it is assumed that the distance estimation accuracy will decrease.

FIG. 7 is a table listing examples of the measurement environment variation factors described above and examples of variation detection means. For example, if the measurement environment variation factor is fading or discoloration of the object, or a change in reflectance of the object, it is possible to detect the change using color temperature. In the case of a distance measuring device 1 using a color sensor 3 as shown in Fig. 1, it is possible to use a ratio of RGB component detection values or an HLS value converted from an RGB component detection value as a parameter similar to color temperature for variation detection. can.

Here, an example of the measurement environment change detection process will be described with reference to the flowchart shown in FIG. 8.

The environmental change detection unit 53 retains parameters similar to the color temperature described above when determining the coefficients of equation (1) last time, and when a certain period of time has elapsed (Y in step S1), the current color temperature of the color sensor 3 is stored. A parameter similar to the color temperature is obtained based on the output value (step S2). Then, the environmental change detection unit 53 compares the obtained parameter similar to the current color temperature with the retained parameter (step S3), and determines whether there is a change in the measurement environment (step S4).

If there is a change in the measurement environment (Y in step S4), the notification unit 54 notifies the user that the coefficients in equation (1) need to be updated (calibrated) (step S5). The notification is made by display or sound. In this case, when the calibration unit 55 performs calibration triggered by a user operation, the environmental change detection unit 53 acquires a parameter similar to the color temperature at that time based on the output value of the color sensor 3, The held parameters are updated to the acquired parameters (step S6). When a certain period of time has passed since step S6, the process moves to step S2 again.

On the other hand, if there is no change in the measurement environment (N in step S4), the calibration is not notified, and after a certain period of time has passed, the process returns to step S2.

In this manner, in this embodiment, by automatically detecting measurement environment fluctuations, it is possible to notify the user of the necessity of calibration and maintain good accuracy of calculation formula 5A. Note that a more specific explanation of the calibration will be given later.

Further, as shown in the table of FIG. 7, if the cause of the measurement environment change is a change in the reflectance of the object or a change in the amount of light from the white LED 4, the change can be detected using illuminance. In the case of a distance measuring device 1 that uses a color sensor 3 as shown in FIG. A total value of detected values (R+G+B, R+G, etc.) can be used. Alternatively, in the case of the distance measuring device 1 using the illuminance sensor 6 as shown in FIG. 6, the output value of the illuminance sensor 6 can be used to detect changes in the measurement environment. Then, by performing the process shown in FIG. 8 described above using the illuminance itself or a parameter similar to the illuminance, it is possible to maintain the accuracy of calculation formula 5A.

Further, as shown in the table of FIG. 7, if the cause of measurement environment variation is the intrusion of external environmental light, the variation can be detected using the illuminance when the white LED 4 is turned off. In the case of the distance measuring device 1 using the color sensor 3 as shown in FIG. get. In the case of the distance measuring device 1 using the illuminance sensor 6 as shown in FIG. 1, the illuminance is acquired based on the output value of the illuminance sensor 6 with the switch SW turned off by the control unit 5 and the white LED 4 extinguished. Then, by performing the process shown in FIG. 8 described above using the illuminance itself or a parameter similar to the illuminance, it is possible to maintain the accuracy of calculation formula 5A.

When comparing the held value of the illuminance (or a similar parameter) when the white LED 4 is turned off with the current value (for example, step S3 in FIG. 8), it is also possible to quantify the degree of parameter variation, for example, as shown below.

For example, the degree of parameter variation can be calculated from equation (2) or equation (3) below.
(Fluctuation level) = | (Current illuminance value) - (Holded illuminance value) | (2)
(Fluctuation level) = | 1 - (current illuminance value) / (held illuminance value) | (3)

In both equations (2) and (3) above, if there is no large discrepancy between the current illuminance value and the held illuminance value, the degree of variation will be approximately 0, and the more the discrepancy occurs, the greater the value of the degree of variation. Therefore, by comparing the degree of change in the calculated parameter with a threshold value, it is possible to determine whether there is a change in the measurement environment.

<6. Calibration>
Here, calibration will be explained. FIG. 9 is a diagram showing a first configuration example of the calibration section 55 included in the control section 5. As shown in FIG. The calibration section 55 shown in FIG. 9 includes a measurement execution section 551 and a calculation formula updating section 552.

The measurement execution unit 551 measures the RGB component detection values by the color sensor 3 based on the user's operation while the distance L between the sensor and the target object (FIG. 2) is set to a desired first distance. Furthermore, the measurement execution unit 551 measures the RGB component detection values by the color sensor 3 based on the user's operation, with the distance L between the sensor and the target object set to a desired second distance. Therefore, the measurement execution unit 551 obtains two points: the actual distance value and the combination of the RGB component detection values. The calculation formula updating unit 552 updates coefficients a and b of the calculation formula 5A expressed by equation (1) based on the acquired two-point data.

When only the calculation formula 5A for one of the RGB components is held in the distance detection unit 52 (that is, there is one calculation formula A), the calculation formula 5A is updated based on the detected value of the one component. When calculation formulas 5A for a plurality of RGB components are retained (that is, there are multiple calculation formulas A), each of the calculation formulas 5A is updated based on the detected values of the plurality of components.

Note that the first configuration example described above is also applicable to a case where the illuminance sensor 6 is used instead of the color sensor 3.

Fig. 10 is a diagram showing a second configuration example of the calibration unit 55 included in the control unit 5. The calibration unit 55 shown in Fig. 10 has a distance calculation unit 553, an error index calculation unit 554, and a calculation formula selection unit 555 in addition to a measurement implementation unit 551 and a calculation formula update unit 552. In the configuration of Fig. 10, when multiple calculation formulas 5A for multiple components of RGB are held, the multiple calculation formulas 5A can be updated and the optimal calculation formula 5A can be selected.

In addition to the two combinations of the actual distance value and the RGB component detected value for use in updating the coefficients of calculation formula 5A, the measurement implementation unit 551 also acquires another combination of the actual distance value and the detected RGB component value. . The calculation formula updating unit 552 updates the coefficients of the plurality of calculation formulas 5A based on the acquired two points of data.

The distance calculation unit 553 calculates the distance by substituting the RGB component detection values obtained above into each calculation formula updated above. As a result, a combination of the actual distance value and the estimated distance value is obtained for each calculation formula 5A. The error index calculation unit 554 calculates an error index for each calculation formula 5A based on the above combination. The error index is, for example, the average value of the error between the actual value and the estimated value and 3σ (σ: standard deviation) of the error. 3σ is an index indicating error variation.

The calculation formula selection unit 555 selects the calculation formula 5A with the highest accuracy based on the error index for each calculation formula 5A calculated above. Thereafter, the distance detection unit 52 measures the distance using the selected calculation formula 5A.

FIG. 11 is a diagram showing a third configuration example of the calibration section 55 included in the control section 5. As shown in FIG. The calibration section 55 shown in FIG. 11 differs from the second configuration example described above in that it includes a 3σ calculation section (variation calculation section) 556 instead of the error index calculation section 554.

In addition to the two combinations of the actual distance value and the RGB component detected value for use in updating the coefficients of calculation formula 5A, the measurement implementation unit 551 also acquires another combination of the actual distance value and the detected RGB component value. . At this time, RGB component detection is performed multiple times (for example, three times) for the actual value of the same distance. The calculation formula updating unit 552 updates the coefficients of the plurality of calculation formulas 5A based on the acquired two points of data.

The distance calculation unit 553 calculates the distance by substituting the RGB component detection values obtained above into each calculation formula updated above. As a result, a combination of the actual distance value and the estimated distance value is obtained for each calculation formula 5A. At this time, a plurality of distance estimates are obtained for the same actual distance value. The 3σ calculation unit 556 calculates 3σ of the estimated distance value for each actual value of the same distance. The calculation formula selection unit 555 selects the calculation formula 5A with the least variation from the plurality of calculation formulas 5A based on the 3σ calculated above. As a result, it is possible to select the calculation formula 5A for components with small variations in detected RGB component values with respect to actual values of the same distance.

<7. Application to equipment>
The distance measuring device 1 according to this embodiment can be used to measure distances to various objects 10. FIG. 12 schematically shows a configuration example in which the distance measuring device 1 is mounted on a toilet tank 150 as an example of an applicable device. In this case, the distance measuring device 1 functions as a water level measuring device that measures the distance L between the color sensor 3 and the liquid level of the water 100 as the object 10, that is, the liquid level height H. The longer the distance L, the shorter the liquid level height H becomes.

As shown in FIG. 12, the toilet tank 150 has a housing section 70. The substrate 2, color sensor 3, and white LED 4 included in the distance measuring device 1 are arranged above inside the housing section 70. The storage section 70 can store water 100. The color of the accommodating portion 70 itself is white. Note that the configuration is not limited to the configuration shown in FIG. 12, and for example, a white sheet material may be placed on the inner bottom surface of the storage section 70, or may be placed below the transparent bottom of the storage section 70. Further, the storage portion 70 may be a container for purposes other than a toilet tank.

<8. Others>
Note that the various technical features disclosed in this specification can be modified in addition to the embodiments described above without departing from the gist of the technical creation. In other words, the above embodiments should be considered to be illustrative and not restrictive in all respects, and the technical scope of the present invention is not limited to the above embodiments, and the claims Ranges and equivalents should be understood to include all changes falling within the range.

<9. Additional notes>
As described above, the distance measuring device (1) according to one aspect of the present disclosure includes:
a light source (4) configured to emit light toward an object (10);
an optical sensor (3) configured to receive reflected light from the target object;
A distance detection unit (52) configured to calculate the distance to the target object based on the light detection value output from the optical sensor and the calculation formula below (first configuration) .
Y=a・X ^b
However, Y is distance, X is light detection value, a and b are coefficients

Further, in the first configuration, the optical sensor (3) detects at least one of the optical detection value of an R (red) component detection value, a G (green) component detection value, and a B (blue) component detection value. is configured to output
The distance detection unit (52) may have a configuration including the calculation formula for at least one of the R component detection value, the G component detection value, and the B component detection value (second configuration).

Further, in the first configuration, the optical sensor (6) is configured to output the photodetected value of illuminance, and the distance detection unit (52) is configured to have the calculation formula for the illuminance. (third configuration).

Further, in any one of the first to third configurations, further comprising an environment change detection section (53) configured to detect a change in the distance measurement environment,
The environment change detection unit detects the presence or absence of the distance measurement environment based on a comparison between a parameter for detecting a change in the distance measurement environment when the coefficient was determined last time and the current parameter. It may be configured as follows (fourth configuration).

Furthermore, in the fourth configuration, the parameter may be a parameter similar to color temperature (fifth configuration).

Furthermore, in the fifth configuration, the parameter similar to the color temperature may be a parameter calculated based on the RGB detection values output from the optical sensor (3) (sixth configuration).

In addition, in the fourth configuration, the parameter may be illuminance or a parameter similar to illuminance (seventh configuration).

Further, in the seventh configuration, the parameter similar to the illuminance is a detected value of one of the RGB components output from the optical sensor (3), or a detected value of one of the RGB components output from the optical sensor (3). A configuration may be adopted in which the total value of the detected values of a plurality of components is used (eighth configuration).

Furthermore, in the seventh or eighth configuration, the parameter may be the illuminance when the light source is turned off, or a parameter similar to the illuminance (ninth configuration).

In addition, in the above-mentioned seventh configuration, the environmental change detection unit (53) may be configured to detect the presence or absence of the distance measurement environment based on the degree of fluctuation of the distance measurement environment calculated by the following formula (tenth configuration).
(fluctuation level) = | (current illuminance value) - (held illuminance value) |
However, the illuminance value also includes the value of a parameter similar to the illuminance.

Further, in the seventh configuration, the environment change detection unit (53) is configured to detect the presence or absence of the distance measurement environment based on the degree of change in the distance measurement environment calculated by the following formula. (11th configuration).
(Fluctuation level) = | 1 - (current illuminance value) / (held illuminance value) |
However, the illuminance value also includes values of parameters similar to the illuminance.

Further, in any one of the fourth to eleventh configurations, a configuration may further include a notification section (54) configured to notify the user when there is a change in the distance measurement environment. 12 configurations).

Further, in any one of the first to twelfth configurations, a measurement execution unit (551) configured to obtain two combinations of the actual distance value and the output value of the optical sensor;
A configuration may further include a calculation formula updating unit (552) configured to update the calculation formula based on the two acquired points, and a calibration unit (55) having the calculation formula update unit (552) (13th configuration). .

Further, in the thirteenth configuration, a calculation formula selection unit (555) configured to select the optimal calculation formula from among the plurality of calculation formulas updated by the calculation formula update unit (552). (fourteenth configuration).

Further, in the fourteenth configuration, further comprising a distance calculation section (553) and an error index calculation section (554),
The measurement implementation unit (551) is configured to also obtain a combination of the actual value of the distance other than the two points and the output value of the optical sensor,
The distance calculation unit is configured to calculate the distance by substituting the obtained output value of the optical sensor into each updated calculation formula,
The error index calculation unit is configured to calculate an error index for each of the plurality of calculation formulas based on a combination of the actual distance value and the distance calculated by the distance calculation unit,
The calculation formula selection unit (555) may be configured to select the calculation formula based on the calculated error index (fifteenth configuration).

Further, in the fourteenth configuration, further comprising a distance calculation section (553) and a variation calculation section (556),
The measurement execution unit (551) also acquires a combination of the actual value of the distance other than the two points and the output value of the optical sensor, and measures the actual value of the same distance multiple times using the optical sensor. configured to carry out measurements of
The distance calculation unit is configured to calculate the distance by substituting the obtained output value of the optical sensor into each updated calculation formula,
The variation calculation unit is configured to calculate a variation in distances calculated corresponding to actual values of the same distance,
The calculation formula selection unit may be configured to select the calculation formula based on the calculated variation (sixteenth configuration).

In addition, in any of the first to sixteenth configurations, the object (10) may be a liquid, and the distance measuring device may be configured as a liquid level measuring device (seventeenth configuration).

Furthermore, the device (150) according to one aspect of the present disclosure includes the distance measuring device (1) of the seventeenth configuration, and a storage section (70) that can accommodate a liquid (eighteenth configuration).

Further, in the eighteenth configuration, the light source (4) further includes a white member disposed below the bottom of the accommodating part (70) or on the bottom surface inside the accommodating part, and the light source (4) emits white light. (19th configuration).

Furthermore, in the eighteenth configuration, the bottom of the housing section (70) may be white, and the light source (4) may be configured to emit white light (twentieth configuration). .

The present disclosure can be used, for example, for distance measurement in various applications.

1 Distance measuring device 2 Board 3 Color sensor 4 White LED
5 Control unit 5A Calculation formula 6 Illuminance sensor 10 Target object 31A, 31B, 31C, 31D Light receiving element 32A, 32B, 32C ADC
33 Logic circuit 34 Infrared cutoff filter 35A Red light transmission filter 35B Green light transmission filter 35C Blue light transmission filter 35D Infrared transmission filter 36 Switch 51 Bit conversion section 52 Distance detection section 53 Environmental change detection section 54 Notification section 55 Calibration section 70 Housing Section 100 Water 150 Toilet tank 551 Assumption implementation section 552 Calculation formula update section 553 Distance calculation section 554 Error index calculation section 555 Calculation formula selection section 556 3σ calculation section R Resistance SW Switch

Claims (20)

a light source configured to emit light toward an object;
an optical sensor configured to receive reflected light from the target object;
a distance detection unit configured to calculate the distance to the target object based on the light detection value output from the optical sensor and the calculation formula below;
A distance measuring device comprising:
Y=a・X ^b
However, Y is the distance, X is the light detection value, and a and b are the coefficients. The optical sensor is configured to output the optical detection value of at least one of an R (red) component detection value, a G (green) component detection value, and a B (blue) component detection value,
The distance measuring device according to claim 1, wherein the distance detection section has the calculation formula for at least one of the R component detection value, the G component detection value, and the B component detection value. The optical sensor is configured to output the optical detection value of illuminance,
The distance measuring device according to claim 1, wherein the distance detection section has the calculation formula for the illuminance. further comprising an environment change detection section configured to detect a change in the distance measurement environment;
The environment change detection unit detects the presence or absence of the distance measurement environment based on a comparison between a parameter for detecting a change in the distance measurement environment when the coefficient was determined last time and the current parameter. The distance measuring device according to claim 1, configured as follows. The distance measuring device according to claim 4, wherein the parameter is a parameter similar to color temperature. The distance measuring device according to claim 5, wherein the parameter similar to the color temperature is a parameter calculated based on RGB detection values output from the optical sensor. The distance measuring device according to claim 4, wherein the parameter is illuminance or a parameter similar to illuminance. The parameter similar to the illuminance is a detected value of one component among the RGB components output from the optical sensor, or a total value of detected values of multiple components among the RGB components output from the optical sensor. The measuring device according to claim 7. The distance measuring device according to claim 7, wherein the parameter is the illuminance when the light source is turned off, or a parameter similar to the illuminance. The distance measuring device according to claim 7, wherein the environmental change detection unit is configured to detect the presence or absence of the distance measuring environment based on the degree of change in the distance measuring environment calculated by the following formula.
(Fluctuation level) = | (Current illuminance value) - (Holded illuminance value) |
However, the illuminance value also includes values of parameters similar to the illuminance. The distance measuring device according to claim 7, wherein the environmental change detection unit is configured to detect the presence or absence of the distance measuring environment based on the degree of change in the distance measuring environment calculated by the following formula.
(Fluctuation level) = | 1 - (current illuminance value) / (held illuminance value) |
However, the illuminance value also includes values of parameters similar to the illuminance. The distance measuring device according to claim 4, further comprising a notification unit configured to notify a user when there is a change in the distance measuring environment. a measurement execution unit configured to acquire two combinations of an actual distance value and an output value of the optical sensor;
a calculation formula update unit configured to update the calculation formula based on the two acquired points;
The distance measuring device according to claim 1 , further comprising a calibration unit having: The distance measuring device according to claim 13, further comprising a calculation formula selection unit configured to select the optimal calculation formula from among the multiple calculation formulas updated by the calculation formula update unit. further comprising a distance calculation section and an error index calculation section,
The measurement implementation unit is configured to also obtain a combination of the actual value of the distance other than the two points and the output value of the optical sensor,
The distance calculation unit is configured to calculate the distance by substituting the obtained output value of the optical sensor into each updated calculation formula,
The error index calculation unit is configured to calculate an error index for each of the plurality of calculation formulas based on a combination of the actual distance value and the distance calculated by the distance calculation unit,
The distance measuring device according to claim 14, wherein the calculation formula selection unit is configured to select the calculation formula based on the calculated error index. The apparatus further includes a distance calculation unit and a variation calculation unit,
the measurement execution unit is configured to acquire combinations of actual distance values other than the two points and output values of the optical sensor, and to execute measurements of the same distance actual values multiple times using the optical sensor;
the distance calculation unit is configured to calculate a distance by substituting the acquired output value of the optical sensor into each updated calculation formula;
The variation calculation unit is configured to calculate a variation of distances calculated corresponding to actual values of the same distance,
The distance measuring device according to claim 14 , wherein the calculation formula selection unit is configured to select the calculation formula based on the calculated variation. The distance measuring device according to any one of claims 1 to 16, wherein the object is a liquid, and the distance measuring device is configured as a liquid level height measuring device. An apparatus comprising the distance measuring device according to claim 17 and a housing section capable of housing a liquid. The device according to claim 18, further comprising a white member disposed below a bottom of the housing or on a bottom surface inside the housing, and wherein the light source is configured to emit white light. 19. The device of claim 18, wherein the bottom of the housing is white and the light source is configured to emit white light.

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