JPS627962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object position measurement method that automatically detects the position of an object, particularly the tip position of a linearly long object or the tip position of an object moving on a straight line, using a photoelectronic method. .

Conventionally, the following two methods have been generally employed as this type of measurement method.

(1) A method of illuminating an object, receiving the reflected light or transmitted light with a plurality of photoelectric conversion elements, and extracting an optical image by sweeping the light (for example, an image sensor).

(2) A method that uses laser light as a light source, uses a rotating mirror or vibrating mirror to sweep illumination of an object as a flying spot, and receives the projected light with multiple photoelectric conversion elements to extract an optical image.

However, in the method (1) above, when the object is linearly long, the reflected light or transmitted light from the object is generally reduced through an optical lens, and the reduced image is received by multiple photoelectric conversion elements. Therefore, it is necessary to make the distance between the object and the photoelectric conversion element relatively long, which increases the size of the device, and it is also technically difficult to obtain uniform illumination. Since the output is taken out for each photoelectric conversion element, there are problems such as requiring an analog multiplexer.

In addition, method (2) above also requires a rotating mirror, a vibrating mirror, and a means for driving them, which increases the size of the device.In addition, when dealing with long objects, the light receiving side also needs to be devised. is required, and there are many problems in production technology.

The present invention was made in view of the above-mentioned circumstances of the prior art, and does not require accessory equipment such as optical lenses, rotating mirrors, vibrating mirrors, analog multiplexers, etc. that were conventionally required to measure long objects. ,
Therefore, the objective is to provide a new method for measuring the position of an object that is inexpensive, compact, and highly accurate, and is particularly useful for measuring the liquid level position of a liquid column meter such as a U-shaped tube or pitot tube. It is an object of the present invention to provide a method for measuring the position of an object that is suitable for measuring the position of an object.

A method for measuring an object according to the present invention includes a light emitting diode array formed by arranging a large number of light emitting diodes at equal intervals on a straight line, a large number of photoelectric conversion elements arranged at equal intervals on a straight line, and , are arranged parallel to the light emitting diode array at a predetermined interval, and receive the projected light of each light emitting diode by a photoelectric conversion element corresponding to the light emitting diode and a photoelectric conversion element in the vicinity thereof, and perform photoelectric conversion thereof. This is carried out using a position measuring device equipped with a photoelectric conversion element array that outputs the total amount of light received by the elements, and a light shielding means that shields the measured object insertion space formed between both arrays from light from the outside. It is something to do. First, as a preliminary work,
A first received light output value when the light emitting diodes are turned on one by one and light is projected onto the middle part of the object to be measured, and a second received light output value when the light is projected without the object to be measured; The third light reception output value when the light emitting diode at the position corresponding to the tip of the object to be measured emits light, and the light emitting diode corresponding to the reference position that is closer to the distance between the light emitting diodes in either direction from the tip of the object to be measured. The fourth light reception output value when the light is emitted is calculated in advance as a reference value. Next, during actual measurement, the light emitting diodes are sequentially turned on from one side to the other over an equal time period at sampling times determined at fixed time intervals, and the first and second received light output values are used as a reference. It is determined whether the fifth received light output value corresponding to the light emission of each light emitting diode is the first or second received light output value, and based on this determination result, the fifth received light output value is the first received light output value.
Or, if it is determined that it is not the second received light output value, it is determined whether the fifth received light output value is an intermediate value between the third and fourth received light output values, and based on this determination result, the fifth received light output value is When it is determined that the output value is an intermediate value between the third and fourth received light output values, the fifth
The position of the light emitting diode corresponding to the received light output value,
The tip position of the object to be measured is calculated based on the third to fifth received light output values and the distance between the light emitting diodes. The above-mentioned "middle part" of the object to be measured is a term for "the tip or the vicinity of the tip," and refers to the entire range of light emission angles (in the arrangement direction of the light emitting diode array) of each light emitting diode that is lit. It means the part that receives.

In this method, the position of each light emitting diode itself serves as a scale, so to speak. Therefore, in the device for implementing this method, the conventionally used optical lens or There is no need to interpose a rotating mirror or a vibrating mirror, and it is only necessary to provide the minimum space necessary to position the object to be measured between them, which has the advantage of being extremely compact and inexpensive to manufacture. . Furthermore, even when using a relatively inexpensive commercially available light emitting diode array with a coarse density, this device uses a microcomputer to sequentially light up the tips of objects located between adjacent light emitting diodes. Very accurate results can be obtained by calculating based on the position of each light emitting diode, the total amount of light received at that time, and a preset reference value.

The present invention is applicable to shape measurement of an object to be measured, or
If it moves in a straight line, it can be applied to measure its moving speed.

The present invention will be specifically described below with reference to the illustrated embodiments.

Figures 1 and 2 show a central longitudinal sectional view and a side view of the device used in this measurement method;
The figure shows its electrical circuit diagram. As shown in FIGS. 1 and 2, in this device, long channel-type light shielding plates 1 and 2 having a U-shaped cross section are placed in parallel with each other at a predetermined interval, and a space 3 in which an object to be measured is placed between them. is formed. And one light shielding plate 1
Light emitting diodes l ₁ to _{l 8} are arranged at equal intervals P on the upper surface 1a of
The light emitting diode array units 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4-, 4- 4-, 4-, 4-, 4--, 4-, 4--, 4-, the light-emitting diode array units 4-, 4-, 4-, 4- are densely arranged in a straight line in the longitudinal direction. Note that the light emitting diodes _l1 and _l8 between adjacent light emitting diode array units
The interval between is also set to P. Further, on the lower surface 2a _{of the} other light shielding plate 2, there are photoelectric conversion element array units 5-, 5-, . ...5- are arranged densely on a straight line in the longitudinal direction, and each photoelectric conversion element m ₁ to m ₈ is made to correspond to each light emitting diode l ₁ to l ₈ in a one-to-one correspondence. For convenience of explanation, each of the above light emitting diodes is sequentially numbered L ₁ , L ₂ , L ₃ , etc. from left to right in the figure.
……Li− ₁ , Li, Li+ ₁ ……L ₆₄ will be given.

To explain the electric circuit with reference to FIG. 3, 6 is a microcomputer, 7, 8, 9, 10, and 11 are the central processing unit of the microcomputer 6, respectively.
These are a storage device, a control panel, a bus line, and an output register for sweeping the light emitting diode. This light emitting diode sweep output register 11 receives a digital signal from the central processing unit 7 of the microcomputer 6 and provides a signal to the driver 12 to sequentially select any one of the light emitting diode array units 4- to 4-. On the other hand, a signal is given to the driver 13 to sequentially select the digits of light emitting diodes _l1 to _l8 in each light emitting diode array unit 4- to 4-. 1st,
The light emitting diodes l _{1 to 4} of each of the light emitting diode array units 4- to 4- described above with respect to FIG.
l ₈ anodes a, a...... are the above driver 13
Each output terminal 13-, 13-......13-
while its cathodes b, b, . . . are connected in common. These common points are connected to output terminals 12- to 12- for selecting the light emitting diode array units of the driver 12, respectively.

On the other hand, each photoelectric conversion element unit 5- to 5-
The collectors of each of the photoelectric conversion elements m ₁ to _{m 8} are collectively connected to the power supply Vcc, while the emitters are also collectively connected to the current-voltage converter 14, and the output terminal of the current-voltage converter 14 is A/D converter 15
It is connected to the. The output terminal of the A/D converter 15 is connected to the microcomputer 6.

The operation procedure for the above configuration is as follows.
That is, from the central processing unit 7 of the microcomputer, light emitting diodes L ₁ , L ₂ ......Li......L are sent from left to right in FIGS. A signal is output that sequentially sweeps ₆₄ on at every fixed sampling time. Each light emitting diode L ₁ , L ₂ ...
...Li......The light projected from L ₆₄ is the corresponding 1
The light is received by one photoelectric conversion element and the nearby photoelectric conversion elements, and each light emitting diode L ₁ , L ₂ ...
Every time L ₆₄ emits light, a total summation current corresponding to the amount of received light is output, which is sequentially converted into a voltage by the current-voltage converter 14, and the voltage is sent to the A/D converter 1.
5, the digital signal is converted into a digital signal, and the digital signal is processed by a microcomputer 6.

Now, as shown in FIG. 4, the transparent glass tube 16 is positioned in the light-shielding space 3 of the measuring device shown in FIG.
An example will be described in which the position of the tip of an object to be measured, specifically, the center bottom position B of the bowl-shaped tip of water 17 is measured.

The present inventors conducted the following experiment using the apparatus shown in FIG.

Example An arbitrary light emitting diode Li was turned on, the water surface position in the transparent glass tube was slowly and continuously moved, and the light reception output was continuously taken out from the photoelectric conversion element array, and each light reception output value was plotted. The results were as shown in FIG.

Figure 5 shows (1) an air region that is constant at the received light output I _A ;
S ₃ , (2) Water area where the received light output is constant I _W (middle part of the object to be measured) S ₁ , (3) Near the water surface where the received light output is V-shaped and the minimum received light output is I _MIN (the object to be measured) It shows that there are three regions of _S2 (near the tip of ).

The formation of these three areas is due to the following causes. In other words, (1) when light is projected onto the air section _S3 , the light is refracted, reflected, and scattered by the glass surface, resulting in a low light receiving output; (2) when light is projected onto the water section _S1 , the light is Since the refractive index of glass is almost equal to
The water part becomes like a cylindrical lens, and light is focused,
The output is larger than when there is only a glass tube or no glass tube. (3) When light is projected near the water surface S ₂ , total reflection occurs at the bowl-shaped tip of the water surface, and the light emitting diode Li is reflected at the bottom of the water surface. When located at point B (the tip of the object to be measured), the received light output becomes the minimum I _MIN , and as it moves away from this position, it has a nearly linear slope due to the light emission angle characteristics of the light emitting diode and the light reception angle characteristics of the photoelectric conversion element. The light receiving output I _W of the water section S ₁ ,
The light receiving output I _A of the air section S ₃ is reached. The horizontal axis dimension of the V-shaped part near the water surface is more than 1.5 times the separation dimension P of the light emitting diodes in the light emitting diode array, and especially the straight slope part on the water part _S1 side is more than 1×P. The amount of change is also large. Detecting the position of the bottom B of the water surface as the water surface position is very convenient in terms of reproducibility and accuracy.

Based on the above experimental results, the present inventors succeeded in accurately measuring the water surface position in a transparent glass tube using the apparatus of the present invention by the following method.

As shown in the above embodiment, in addition to obtaining the light receiving output values I _W , I _A , and I _MIN of the photoelectric conversion element array in advance, the minimum light receiving output value I in the portion S ₂ near the water surface
The received light output value I _P at a point B _P separated from _MIN by the distance P of the light emitting diode toward the left in Fig. 5
Find in advance.

Now, to explain the case of actually measuring the water surface position, first of all, in order to know the water surface condition,
At each sampling time, the light emitting diodes at the beginning of the light emitting diode array L ₁ to L ₂ , L ₃ ......
Li......L ₆₄ are turned on in order for a certain period of time, and each time, a signal obtained by digitizing the light reception output value of the photoelectric conversion element array 5 is read by the storage device 8 of the microcomputer 6, and each light reception output value is Regarding Ii, whether it belongs to the water region S ₁ (=I _W ) or the region S ₂ near the water surface (I _W > Ii
> I _MIN ), and when it enters the area S ₂ near the water surface, it determines whether it is between the minimum received light output value I _MIN and the received light output value I _P ( _IP > Ii > I _MIN ). do. When the received light output value Ii enters this section, the distance between the light emitting diode Li corresponding to the received light output value Ii and the water surface can be calculated from the following formula (1), so = Ii - I _MIN /I _P - I _MIN・P...
......(1) The water surface position B can be determined using the following equation (2).

B=i・P+Ii−I _MIN /I _P −I _MIN・P
(2) The above calculation is performed by the central processing unit 7 by storing equation (2) as a program in the storage device 8 of the microcomputer 6 in advance.

Therefore, according to this device, the position of the liquid level can be detected with a reading accuracy that is several times higher than the minimum scale of the light emitting diode array, that is, the distance P between the light emitting diodes. For example, even if you use a commercially available inexpensive 1/10 inch pitch light emitting diode array, the
Detection of up to 100 inches or ±0.25 mm is possible.

If the water surface position moves and you want to know the speed of movement, you can find it by dividing the amount of change in the water surface position in the sampling time interval by the sampling time interval.

Next, as shown in FIG. 6, a long object 20 that does not transmit any light is placed in the light-shielding space 3 of the measuring device shown in FIG. 1, and the tip position of the long object 20 is measured. I will explain about it.

The present inventors conducted the following experiment using the apparatus shown in FIG. 6, and obtained results different from those obtained in the case of the water-filled transparent glass tube described above.

Experimental example: Turn on any one light emitting diode Li, move the elongated object 20 slowly and continuously, and continuously extract the light reception output from the photoelectric conversion element array 5.
Each received light output value was plotted. The results were as shown in FIG.

Figure 7 shows (1) an air region that is constant at the received light output I _A ;
There are three regions: S ₃ , (2) object part S ₁ where the received light output is constant at I _L , and (3) near the object tip S ₂ where the received light output changes linearly from I _L to I _A. It shows. The horizontal axis dimension in the region _S2 is more than twice the separation dimension P of the light emitting diodes in the light emitting diode array 4, and the distance between the photoelectric conversion element array 5 when the tip B of the object is directly below the light emitting diodes Li. The light receiving output value Ib becomes (I _A +I _L )/2, and further becomes the light receiving output value I _P at a point BP separated from point B in FIG. 7 by the distance _P of the light emitting diode.

Now, to explain the case of actually measuring the tip position of an object, first, at each sampling time, the light emitting diodes at the first end of the light emitting diode array are measured from L ₁ to L ₂ , L ₃ ......Li......L ₆₄ for a certain period of time, and each time, the memory device 8 of the microcomputer 6 reads the digital signal of the received light output value of the photoelectric conversion element array, and for each received light output value Ii, it is determined whether it is an object or not. It is determined whether the object belongs to the area S ₁ near the tip of the object (=I _L ) or to the area S ₂ near the tip of the object (I _L < Ii < I _A ), and furthermore, when it enters the area S ₂ , , it is determined whether the received light output value falls between I _P and Ib (I _P <Ii<Ib). If the received light output value Ii falls within this range, the dimensions can be calculated from the following formula (3), =Ii-Ib/I _P -Ib・P......
(3) The tip position B of the object can be found using the following formula.

B=i・p+Ii+Ib/I _P −Ib・P……
(4) Although in the above embodiment, the lighting order of the light emitting diodes is set in the direction from L ₁ to L ₆₄ , the tip position of the object to be measured can also be measured in the opposite direction. In this case, each received light output value L ₁ is first
It goes without saying that it is determined whether the object belongs to region _S3 or region _S2 .

As explained above, according to the present invention, there is no need for instruments such as optical lenses, rotating mirrors, or vibrating mirrors required in conventional measuring methods, and the apparatus for carrying out the measurement is basically commercially available. Since the structure is formed by linearly arranging a plurality of light emitting diode array units and photoelectric conversion element array units each having a relatively coarse pitch, the structure is very simple and the manufacturing cost is also very low. In addition, since the position of each light emitting diode in the light emitting diode array is used as a scale to indicate the tip position of the object to be measured, its rough position corresponds to the light reception output of the photoelectric conversion element array when the light emitting diode is lit. Therefore, it can be easily detected based on the light emitting diode position, and the light received by the photoelectric conversion element array corresponds to the lighting of one light emitting diode depending on the light emission angle characteristics of the light emitting diode and the light reception angle characteristics of the photoelectric conversion element. Calculation is performed using the photoelectric conversion element at the position and the photoelectric conversion elements in its vicinity, so even if the tip position of the object to be measured is between adjacent light emitting diodes, the calculation is performed using a predetermined reference value. This allows the position to be determined with great precision.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a central vertical sectional view of the position measuring device, FIG. 2 is a side view of FIG. 1, FIG. 3 is an electric circuit diagram of the position measuring device, and FIG. The figure is a central vertical sectional view corresponding to Figure 1 when measuring the water surface position in a transparent glass tube, and Figure 5 is the light reception of the water-filled transparent glass tube and the photoelectric conversion element array for each light emitting diode in Figure 4. A graph showing the output in contrast. Figure 6 is a central vertical cross-sectional view corresponding to Figure 1 when measuring the tip position of an opaque object. Figure 7 is a graph showing the photovoltaic output for the object and each light emitting diode in Figure 6. It is a graph which shows the light reception output of a conversion element array comparatively. 1, 2... Light shielding plate, 3... Space, 4... Light emitting diode array (4-, 4-......4-...
...Light emitting diode array unit, _l1 to _l8 ...Each light emitting diode), 5...Photoelectric conversion element array (5-, 5-...5-...Photoelectric conversion element array unit, _m1 to _m8 ... ...Each photoelectric conversion element),
6...Microcomputer, 7...Central processing unit, 8...Storage device, 9...Control panel, 10...Bus line, 11...Output register, 12, 13...Driver, 14...Current voltage conversion container, 15...A/D converter, 16...transparent glass tube, 17...water, 20...long object.

Claims (1)

[Claims] 1. A light emitting diode array consisting of a large number of light emitting diodes arranged at equal intervals on a straight line, and a large number of photoelectric conversion elements arranged at equal intervals on a straight line, and at a predetermined interval with respect to the light emitting diode array. The light emitting diodes are arranged in parallel with each other, and the light emitted from each light emitting diode is received by a photoelectric conversion element corresponding to the light emitting diode and a photoelectric conversion element in the vicinity thereof, and the total amount of light received by those photoelectric conversion elements is output. A method for measuring the position of an object using a position measuring device comprising a photoelectric conversion element array having a photoelectric conversion element array and a light shielding means for shielding a space for inserting the object to be measured formed between the two arrays from light from the outside. ,
As a preliminary work, we turned on the light emitting diodes one by one and measured the first light reception output value when the light was projected onto the middle part of the object to be measured, and the second light reception value when the light was projected without the object to be measured. The output value, the third light reception output value when the light emitting diode at the position corresponding to the tip of the object to be measured emits light, and the reference position that is closer to the distance between the light emitting diodes in either direction from the tip of the object to be measured. The fourth light reception output value when the corresponding light emitting diode emits light is calculated in advance as a reference value, and during measurement, the light emitting diode is measured once at an equal time interval at each sampling time determined at a certain time interval. Turn on the light from one side to the other one after another, and check whether the fifth light reception output value corresponding to the light emission of each light emitting diode is the first or second light reception output value based on the first and second light reception output values. and if it is determined that the fifth received light output value is not the first or second received light output value based on this determination result, the fifth received light output value is the intermediate value of the third and fourth received light output values. If it is determined from this determination result that the fifth received light output value is an intermediate value between the third and fourth received light output values, the light emission corresponding to the fifth received light output value is determined. A method for measuring the position of an object, characterized in that the position of the tip of the object to be measured is calculated based on the position of the diode, the third to fifth received light output values, and the distance between the light emitting diodes.