JPH07104161B2 - Level sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a level sensor for discriminating the height between two points in a survey, and in particular, it receives a laser light source from a laser light source installed at one of the measurement points. , A level sensor for comparing the level with a laser light source.

[Conventional technology]

In recent years, when performing leveling between two points, a laser light source may be installed at one of the measurement points and a level sensor that receives a laser beam and compares the height with respect to the light source may be used at the other.
A conventional level sensor of this type is as shown in FIG.

In FIG. 6, one surface of the level sensor 10 is a light receiving surface.
The light receiving surface 12 is provided with a vertically long rectangular light receiving portion 14. A laser light source (not shown) is installed in front of the light receiving surface 12, and the laser light 16 is rotated in a constant cycle in a horizontal plane as shown by an arrow 18.

Further, the level sensor 10 is provided with a display 20 made of liquid crystal on a surface different from the light receiving surface 12. The display 20 is the seventh
As shown in the figure, when the laser beam 16 passes above the center of the light receiving unit 14 in the vertical direction, an upward arrow 22 indicating an instruction to move the level sensor upward, the laser beam 16 moves up and down the light receiving unit 14. A bar indicating that the center of the direction has been passed
24, and a downward arrow 26 that displays an instruction to move the level sensor downward when the laser beam 16 passes below the center of the light receiving unit 14 in the vertical direction.

[Problems to be Solved by the Invention]

However, the conventional level sensor 10 described above is
The level can be obtained only when the laser beam crosses the vertical center of the light receiving section 14, and the level sensor is moved up and down when measuring the level so that the laser beam 16 passes through the vertical center of the light receiving section 14. Therefore, not only the work is complicated but also a lot of time is required. For this reason, when creating a land with many irregularities, it is necessary to frequently use the level sensor when excavating the land. Since it takes time, it is a factor that hinders the rapid progress of construction.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a level sensor that can reduce the number of steps for level measurement and can easily perform level measurement.

[Means for Solving the Problems]

In order to achieve the above object, the level sensor according to the present invention includes an optical sensor including a light receiving element array that detects a light beam from a light source and outputs an electric signal, and only the electric signal that is intermittent for each light receiving element. Capacitor for passing, and for the intermittent electric signal output by the multiplexer after passing through the capacitor, an amplifier for generating a rectangular wave composed of at least three stages of transistors and a saturated output, and an edge of the generated rectangular wave, and calculating A signal holding circuit consisting of a monostable multivibrator that holds the read request from the control circuit, and a channel selection signal to the multiplexer, and holding and reset control to the signal holding circuit. And an operation control circuit that sequentially reads the output from the high or low signal holding circuit. Characterized in that it has.

[Action]

According to the present invention configured as described above, since the light sensor is composed of a plurality of light receiving elements, when a light beam such as a laser beam is incident on the light sensor, only the light receiving element hit by the light beam outputs an electric signal. . Then, the multiplexer to which each learning element of the optical sensor is connected receives the channel selection signal from the arithmetic control circuit, sequentially outputs the detection signal of each light receiving element, and inputs the detection signal to the signal holding circuit. The signal holding circuit holds the signal input from the multiplexer until the arithmetic control circuit reads it. Then, the arithmetic control circuit calculates which position of the optical sensor the light beam crosses based on the detection signal of each light receiving element read from the signal holding circuit.

Therefore, it is possible to easily judge the height of the light source and the level sensor and the degree thereof, and the number of man-hours for level measurement is reduced, so that level measurement can be performed easily and quickly, and construction such as land preparation can be promoted. .

〔Example〕

A preferred embodiment of the level sensor according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a level sensor according to an embodiment of the present invention.

The level sensor 30 is composed of a plurality of light receiving elements 34, as the optical sensor 32 will be described later in detail. Each light receiving element 34 has one terminal connected to a DC power source, the other terminal grounded via a load resistance _RL, and an analog multiplexer (via a coupling capacitor C _C for cutting a DC component). Hereinafter referred to simply as a multiplexer)
It is connected to the input terminals of 36 _{A to} 36 _M , and when a light beam such as a laser beam is incident, it inputs an electric signal to the multiplexers 36 _{A to} 36 _M.

Each of the multiplexers 36 _{A to} 36 _M has one output terminal S and eight or 16 input terminals (channels), and the light receiving element 34 is connected to each of the input terminals via a coupling capacitor C _C. . Then, the output terminal S of the multiplexer 36 _A ~ 36 _M are is coupled to the input terminal of the amplifier 38 _A to 38 DEG _M for amplifying the detection signal receiving element 34 is output. Further, the multiplexers 36 _{A to} 36 _M are adapted to receive a channel selection signal from the arithmetic control circuit 42 composed of a microcomputer, and the channel selection signal from the arithmetic control circuit 42 causes the input terminals to output the output terminal S. The connection is sequentially switched, and the output signal of the light receiving element 34 connected to each input terminal is sequentially input to the amplifiers 38 _{A to} 38 _M.

The output side of the amplifiers 38 _{A to} 38 _M is connected to the input side of the signal holding circuit 40 _A to 40 _M including, for example, a monostable multivibrator, and amplifies the signals output from the multiplexers 36 _{A to} 36 _M. Shape the waveform and input it to the signal holding circuits 40 _A to 40 _M. Each signal holding circuit 40 _A to 40 _M, when the signal from the amplifier 38 _A to 38 DEG _M comes to enter, holds the signal by a predetermined time, receiving a read signal from the arithmetic control circuit 42, The held signals are simultaneously output to the arithmetic control circuit 42. The arithmetic control circuit 42, based on the signal input from each of the signal holding circuits 40 _A ~ 40 _M , the light receiving element 34 hit by the light beam, that is, by calculating which position of the optical sensor 32 the light beam has passed, The calculation result is output to the display device 60 and displayed.

The optical sensor 32, as shown in FIG.
It consists of 34 _{A to} 34 _N. Each of the light receiving elements 34 _{A to} 34 _N is formed, for example, in a rectangular parallelepiped shape having a length l, a width b, and a thickness t, and the width direction is the height (length) direction of the optical sensor 32. Are placed in line with each other. And
Each of the light receiving elements 34 _{A to} 34 _N has a photosensitive portion 44 at the center in the length direction, and electrode portions 46 and 48 are formed at both ends of the photosensitive portion 44.

The light receiving elements 34 _{A to} 34 _N need only have a size capable of detecting a light beam, and the length l is several mm (for example, 5 mm),
A width b of 1 mm can be used. If you want to improve the accuracy of the level sensor 30, set the width of the light receiving element 34 to 1 mm.
Although it is desirable to set it to the following, a device with a width of 1 mm is sufficient if the tolerance is about several mm. Then, the light receiving element 34
Is for converting an optical signal of a photodiode, a phototransistor, a photo Darlington transistor, or the like into an electric signal, which may be crystalline or amorphous.

The length h of the optical sensor 32 is preferably several tens mm or more,
If possible, it should be at least 80 mm and a sufficient length of at least 160 mm.

The operation of the embodiment configured as described above is as follows.

A light beam (laser light) from a light source (not shown) revolves at a predetermined cycle. Then, the level sensor 30, power is the arithmetic control circuit 42 is actuated on, sends a constant period, the channel selection signal, for example in synchronization with the turning period of the laser light to the multiplexer 36 _A ~ 36 _M. When the first channel selection signal is input from the arithmetic and control circuit 42, each of the multiplexers 36 _{A to} 36 _M turns on the first input terminal and the output terminal S, and connects to the first input terminal. The detection signal of the light receiving element 34 is sent to the amplifiers 38 _{A to} 38 _M.

Each of the amplifiers 38 _{A to} 38 _M amplifies the detection signal of the light receiving element 34 output from the multiplexers 36 _{A to} 36 _M to shape the waveform, and the output signal of the light receiving element 34 hit by the light beam is “H” (high), the output signal of the light receiving element 34 which light is not hit and sends it to the signal holding circuit 40 _a to 40 _M as "L" (low). Signal holding circuit
40 _A to 40 _M are held for a certain period of time so that the arithmetic and control circuit 42 can capture the signals output from the amplifiers 38 _{A to} 38 _M. The signals are held by the signal holding circuits 40 _A to 40 _M for the following reason.

Since the light beam emitted from the light source is rotated in a predetermined cycle, the time when the light beam crosses the optical sensor 32 is extremely short, and even when the light beam is incident on a certain light receiving element 34 _I , the light beam does not hit the light receiving element 34 _I. Is much longer. For this reason,
The multiplexers 36 _{A to} 36 _M must wait until the detection signal arrives from the light receiving element 34, and whether the arithmetic control circuit 42 has entered the light receiving element 34 with a light beam (signal holding circuits 40 _A to 40 _{M). This} is because it is necessary to hold the signal until it is judged whether the signal held by _M is “H” or “L”.

That is, the light ray generally turns in a cycle of about 0.1 second to 1 second. Therefore, the time for which the light beam crosses the optical sensor 32 during one turn of the light beam is several microseconds when the distance between the level sensor 30 and the light source is 100 m. Therefore, since the multiplexers 36 _{A to} 36 _M input the detection signal of the light receiving element 34 when the light ray of the light receiving element 34 connected to the selected channel hits the amplifier 38, the light rays are transmitted to the optical sensor 32.
It is necessary to turn on the selected channel until it crosses over, that is, for about 0.1 second to 1 second. Moreover, the light beam detection signal of the light receiving element 34 amplified by the amplifier 38 is several microseconds, and the light receiving element 34 receives light for about 0.1 second to 1 second at which the arithmetic control circuit 42 can determine whether or not a light ray is incident on the light receiving element 34. This is because it is necessary to hold the signal output by the element 34.

Each of the signal holding circuits 40 _A to 40 _M receives the read signal from the arithmetic control circuit 42 and simultaneously holds the held signals at the same time.
Send to. The arithmetic control circuit 42 is a signal holding circuit 40 _A to 40 _M.
Upon receiving a signal from, it clears the signal in the signal holding circuit 40 _A to 40 _M holds send clear signal. And
Arithmetic and control circuit 42, the level of the signals that have entered from the signal holding circuit 40 _A to 40 _M "H", examines the "L", and stores in correspondence with the light receiving elements in a memory (not shown) results.

The arithmetic control circuit 42, and at the same time sends a clear signal to the signal holding circuit 40 _A to 40 _M, sends a channel selection signal to the multiplexer 36 _A ~ 36 _M, 1 of each multiplexer 36 _A ~ 36 _M
Turn off the second input terminal and output terminal S, and
The second input terminal and the output terminal S are turned on, and the detection signal of the light receiving element 34 connected to the second input terminal is fed to the amplifier 38 _A.
Input to ~ 38 _M.

Hereinafter, after reading the state of the output signal of the light receiving element 34 connected in a similar manner to the last input terminal of the multiplexer 36 _A ~ 36 _M, whether the light rays strike the light sensor 32, light sensor 32
Of the position where the ray of light passes, the diameter of the ray of light, the distance from the center of the optical sensor 32 at the position of the ray of light, and the like, and the display device 60
Output to and display.

In this way, the level sensor 30 of the embodiment obtains the position on the light sensor 32 through which the light beam passes and displays it on the display device 60, so that the position of the light sensor 32 on which the light beam hits can be read immediately, and the level The number of measurement steps can be reduced, and measurement can be performed easily and quickly. As a result, the man-hours for construction such as land preparation can be reduced and the construction can be promoted.

Moreover, it is possible not only to immediately know how far the light beam passage position is from the vertical center of the optical sensor 32, but also to determine the light beam passage position with any light receiving element 34 of the optical sensor 32 as a reference point. Can also be asked. Further, the diameter of the light ray can be known from the number of the light receiving elements 34 hit by the light ray, and it can be judged whether or not the size of the light ray is within the normal range. Then, it can be determined whether or not the light beam is protruding from the optical sensor 32 depending on whether or not the light beam has hit the light receiving element 34 at the uppermost stage or the lowermost stage.

<Specific Example> FIG. 3 shows a specific example of the level sensor according to the present invention.

In FIG. 3, the light receiving element 34 of the optical sensor 32 is a photodiode D. As shown in FIG. 4, ten photodiodes D are formed on one chip 50. The optical sensor 32 has 16 chips 50 arranged in a line,
It is composed of ₁₆₀ photodiodes D _{1 to} D ₁₆₀ .

In each chip 50, boron is diffused as P type into an N type single crystal silicon substrate 52, and ten photodiodes D _{1 to} D ₁₀ each having a PN junction are formed at equal intervals. And tip 50
The width from 4 mm, 1 th center of the photodiode D ₁ 1
The distance to the center of the 0th photodiode D ₁₀ is 10 mm.

Photodiodes D _{1 to} D constituting the optical sensor 32
₁₆₀ has its cathode side connected to the power supply V _D , its anode side grounded via load resistors R _{L1 to} R _L160 , and multiplexers 36 _{1 to} 3 via coupling capacitors C _{C1 to} C _C160.
6 ₂₀ is connected to the input terminal 1IN~8IN of, for example, a reverse bias voltage of 3V is applied.

The multiplexers 36 _{1 to} 36 ₂₀ have eight channels with eight input terminals, and the output terminals OUT are each multiplexers 36 ₁ to 36 _20.
It is connected to the inputs of amplifiers 38 _{1 to} 38 ₂₀ provided corresponding to 36 ₂₀ . Further, the multiplexers 36 _{1 to} 36 ₂₀ are connected to the arithmetic control circuit 42 including level converters A, B, and C, which are microcomputers, and the arithmetic control circuit 42 outputs a channel selection signal and an inhibit signal for turning off all channels. It is designed to receive signals.

Each of the amplifiers 38 _{1 to} 38 ₂₀ has, as shown in the example of the amplifier 38 ₁ ,
The base of the PNP type transistor TR ₁ is connected to the multiplexer via the coupling capacitor C ₁ that cuts off the DC component. The base of the transistor TR _1, together with certain connected to the circuit power supply V _CC through a resistor R _2, R _1, resistors R _3, R
It is grounded through ₉ . A capacitor C ₂ is connected in parallel with the resistor R ₁ . Also, the transistor TR
₁ has resistors R ₁ , R ₂ , R ₃ and R ₉ adjusted so that it is turned on when the input of the base is 10 mV or less.

The emitter of the transistor TR ₁ is connected to the power supply V _CC , and the cholester is grounded via the resistor R ₄ , and
It is connected to the base of the NPN transistor TR ₂ via a coupling capacitor C ₃ that cuts a direct current component, and the output signal generated in the coresta is input to the base of the transistor TR ₂ .

The base of the transistor TR ₂ is connected to the power supply V _CC via the resistor R ₅ , and is also grounded via the bypass capacitor C ₄ connected in parallel to the resistors R ₆ , R ₇ and the resistor R ₇ . The bypass capacitor C ₄ removes the AC noise component of the signal input to the base of the transistor TR ₂ . The collector of the transistor TR ₂ is connected to the power supply V _CC via the resistor R _{8 and also} to the base of the NPN transistor TR ₃ , and the output signal of the transistor TR ₂ is connected to the base of the transistor TR ₃ . To enter. And the transistor TR ₂
Its emitter is grounded through resistor R ₉ . However,
Resistors R _8, R _9, the resistance value is selected to be R ₈ >> R _9.

The transistor TR ₃ has the collector serving as the output terminal of the amplifier 38, is connected to the power supply V _CC via the resistor R _10, and is connected to the input terminal of the signal holding circuit 40.
The output signal appearing at the collector can be input to the signal holding circuit 40. Further, the emitter of the transistor TR ₃ is grounded.

Signal holding circuit 40 ₁ to 40 ₂₀ is composed of a monostable multivibrator, timing resistor R _T1 to R _T20 and timing capacitor C _T1 -C for each signal holding circuits 40 ₁ to 40 ₂₀ to adjust the pulse width to be output _T20 is attached externally. Also,
The output terminals Q of the signal holding circuits 40 ₁ to 40 ₂₀ are connected to the arithmetic control circuit 4
2 are connected to the input terminals IN1 to IN20, and the signal holding circuit 40
_The signals held by _A to 40 _M can be input to the arithmetic control circuit 42. A display device 60 including, for example, a liquid crystal element is connected to the output side of the arithmetic control circuit 42.

When the level sensor 30 is powered on, the arithmetic control circuit 42
The multiplexer 36 _{1-36 20} terminal A of the, B, and sends a channel selection signal to the C, and connects the first input terminal 1IN of each multiplexer 36 _{1-36 20} to the output terminal OUT. This allows the photodiode D connected to each input terminal 1IN
₁ , D ₉ , D ₁₇ , ... D ₁₅₃ detection signal is a coupling capacitor
Multiplexer 36 ₁ through C _C1 , C _C9 , C _C17 , ... C _C153
~ 36 ₂₀ and input from multiplexer 36 ₁ ~ 36 ₂₀ to amplifier 3
It is output to 8 _{1 to} 38 ₂₀ .

The amplifiers 38 _{1 to} 38 ₂₀ output “H” when no signal is input from the multiplexers 36 _{1 to} 36 ₂₀ (when the light beam does not strike the photodiode D).

That is, when no signal comes in from the multiplexers 36 _{1 to} 36 ₂₀ the transistor TR ₁ of the amplifiers 38 _{1 to} 38 ₂₀ has a low base voltage and is in the ON state because the base current flows through R ₃ and R _9. It is in. The transistor TR _2, to the transistor TR ₁ is turned on, the transistor TR ₁
When the output of is input to the base and is on, current flows from the collector to the emitter. The collector resistor R ₈ and the emitter resistance R ₉ of the transistor TR _2, as described above R ₈
>> Due to the relationship of R _9, the collector voltage drops due to the voltage drop across the resistor R ₈ . Therefore, the transistor TR ₃
Is in the off state because the base voltage is low. Therefore, the collector voltage of the transistor TR ₃ which is the output of the amplifiers 38 _{1 to} 38 ₂₀ becomes the power supply voltage V _CC , and the signal holding circuits 40 ₁ to 40
“H” is input to the ₂₀ input terminals. Then, the signal hold circuit 40 _A to 40 _M, and outputs the "L".

When a light ray hits the photodiode D, the signal holding circuit 40 corresponding to the photodiode D hit by this light ray.
The output of the _{1-40 20} is held in a predetermined time "H".

That is, a reverse bias voltage is applied to the photodiode D, and a photocurrent flows when a light beam hits the photodiode D.
A voltage of mV or more is input to the amplifier 38 via the coupling capacitor C _C and the multiplexer 36. This input signal is applied to the base of the transistor TR ₁ via the coupling capacitor C ₁ and raises the base voltage of the transistor TR ₁ . Therefore, the transistor TR ₁ is turned off, and the current flowing through the emitter of the transistor TR ₁ is reduced. Therefore, the voltage drop due to the emitter resistance R ₄ of the transistor TR ₁ becomes small and the emitter voltage drops, and this drop in voltage is caused by the transistor C ₁ via the coupling capacitor C _3.
It is transmitted to the base of TR _2, lowering the base voltage of the transistor TR ₂ to turn off the transistor TR ₂ and. When the transistor TR ₂ is turned off, the collector voltage of the transistor TR ₂ rises. Since the base of the transistor TR ₃ is directly connected to this collector, when the collector voltage of the transistor TR ₂ rises, the transistor TR ₃ is immediately turned on and becomes saturated. Therefore, in the transistor TR ₃ , the collector voltage becomes almost the ground voltage, and the signal holding circuits 40 ₁ to 40
The outputs of the amplifiers 38 _{1 to} 38 ₂₀ input to the ₂₀ terminals change from “H” to “L”.

When the input of the signal circuits 40 ₁ to 40 ₂₀ changes to “L”, the signal holding circuits 40 ₁ to 40 ₂₀ are triggered and the signal holding circuit 40 _A
The output of ˜40 _M becomes “H”, and this “H” is held for a predetermined time depending on the product of the timing resistor R _T and the timing capacitor C _T. It is desirable that the time for holding "H" is longer than the turning cycle of the light beam. For example, when the turning cycle of the light beam is 0.2 seconds, the holding time is set to 1 second.

The arithmetic control circuit 42 gives a read signal to the signal holding circuit 40 ₁ to 40 _20, determines whether it is "H", "L" to read the signals each signal holding circuits 40 ₁ to 40 ₂₀ outputs Then, the result is stored in the memory in association with the photodiodes D ₁ , D ₉ , D ₁₇ , ... D ₁₅₃ . Then, the arithmetic control circuit 42
When data storage is complete, in order to prevent interference with the next signal, input a clear signal to the terminals of each signal holding circuit 40 ₁ to 40 ₂₀ and change the signal held by the signal holding circuit 40 ₁ to 40 _20. At the same time as clearing, a channel selection signal is sent to the multiplexers 36 _{1 to} 36 ₂₀ to turn off the 1IN terminal and turn on the 2IN terminal. The transmission cycle of this channel selection signal is
It is synchronized with the turning cycle of the light beam.

When the channels of multiplexers 36 _{1 to} 36 ₂₀ are switched from ₁ IN to 2 IN, photodiodes D ₂ , D ₁₀ , D ₁₈ , ...
… The output signal of D ₁₅₄ is the coupling capacitors C _C2 , C _C10 , C ₁₈ ,…
… Amplifier 38 ₁ via C ₁₅₄ and multiplexers 36 _{1 to} 36 ₂₀
Enter ~ 38 ₂₀ .

The arithmetic and control circuit 42 then repeats in the same manner for each multiplexer 36.
_1-36 examined ₂₀ output signal of the photo diode connected to all the 8IN terminal and stored in the memory, computes the position or the like the rays of the light sensor 32 passes.

As in this embodiment, 8-bit multiplexers 36 _{1 to} 36 _{1
When 20} is used, it takes eight times as long as the turning period of the light beam to capture all the output signals of the photodiodes D _{1 to} D ₁₆₀ into the arithmetic control circuit 42.
When it is 0.2 seconds, the operation control circuit 42 detects that the photodiode D
_It will take 1.6 seconds to capture the output of _{1 to} D ₁₆₀ .

The light rays are generally in the range of 5-40 mm in diameter. Therefore,
When the light beam crosses the optical sensor 32, a plurality of photodiodes receive the light beam, and the detection signal of the photodiode D hit by the light beam is “H” in the memory of the arithmetic control circuit 42.
The detection signal of the photodiode D which is not hit by the light beam is stored as "L". Therefore, the arithmetic control circuit 42
Is the position of the uppermost and lowermost photodiodes hit by the light beam from the data stored in the memory, calculates the median value, and outputs it to the display device 60 as the position of the light beam passing through the optical sensor 32. , And how much the light beam passage position deviates from the center of the optical sensor 32.

In addition, the arithmetic control circuit 42 obtains the number of photodiodes hit by the light ray, and when the number is 40 or more, or 5
When it is the following, the fact is displayed on the display device 60 to notify the possibility that the light source has an abnormality. Further, the arithmetic control circuit 42
If the light beam does not hit the optical sensor 32, displays that fact. Then, when the light beam hits the uppermost photodiode D ₁ or the lowermost photodiode D ₁₆₀ , the arithmetic control circuit 42 may cause the light beam to protrude from the optical sensor 32, and thus the display device 60 When `` Measurement is not possible '' is displayed on the screen, and when the light beam hits the uppermost photodiode D ₁ , an instruction to raise the level sensor 30 is displayed, and when the light beam hits the lowermost photodiode D _160. , A display instructing to lower the level sensor 30 is displayed.

The following table compares the measurement results according to the above examples with the measurement results according to the scale.

As described above, the measurement by the level sensor of the embodiment has an error of ± 1 mm or less, and can be sufficiently put to practical use.

Incidentally, as shown in FIG. 5, the output signal of the light receiving element 34 _A to 34C _N, via a coupling capacitor C _C and amplified directly input to the amplifier 38 _A to 38 DEG _N, amplifier 38 _A to 38 DEG _N The signal holding circuits 40 _A to 40 _N hold the output of the above for a predetermined time, and the output of this signal holding circuit 40 _A to 40 _N is passed through multiplexers (including digital multiplexers) 62 _{A to} 62 _M to the arithmetic control circuit 42. You can enter it in. However, in this case, it is necessary to provide the amplifier 38, the signal holding circuit 40, etc. corresponding to each of the light receiving elements 34 _{A to} 34 _N , which not only complicates the circuit but also becomes uneconomical.

It should be noted that, in the above-described embodiment, the measurement is performed when the light source and the level sensor 30 are at substantially the same height (level), but if the emission angle of the light beam of the light source can be adjusted, the light source and the level sensor 30 can be adjusted. It can also be applied to measurements where and are different heights.

〔The invention's effect〕

As described above, according to the present invention, the optical sensor is configured by the light receiving element array, the detection signal of the light receiving element is temporarily held by the signal holding circuit, and the output signal of the signal holding circuit is sent to the arithmetic control circuit. Since the position of the light receiving element that receives the input light beam is obtained, the level for the light source can be easily obtained, and construction work such as land preparation can be carried out quickly.

In the level sensor according to the present invention, it is essential to use at least three stages of transistors in a structure having an amplification function. This is because, in the conventional operational amplifier, for example, the rotational speed of the laser beam is representative. When set to 1rps, 100m or more,
In some cases, the saturation voltage may not be reached even at a distance of 50 m or less. 2. There are also ultra-high-speed operational amplifiers, but they have high power consumption,
When power consumption is suppressed, there is a drawback that high-speed responsiveness is lost.
This is because things like this do not happen.

Also, by combining three or more stages, even if there are variations in h _fe between individual transistors and temperature dependence, the amplification factor is high, so that saturation is sufficient and reliability can be secured. Further, even if the resistance of the amplifier is increased, the high-speed response is not impaired, so that the power consumption is reduced and the outdoor use can be performed for a long time.

Then, if the signal from the amplifier is digitized, it is not necessary for the signal circuit in the next stage to adopt a sample hold circuit that also supports analog signals.
A monostable multivibrator dedicated to digital signal processing based on (0,1) judgment is sufficient. If you do so, the rate of picking up noise will decrease and you will be more certain.

For example, rotating a 2 mm diameter laser beam at 1 rps gives 100
At a distance of m, the light shining on the light receiving surface of the measuring device is much shorter than 1 second (for example, several tens of μse).
c) If there is no monostable multivibrator, the signal may be erroneous even if the target light receiving element is scanned by a command from the computer. When the sample pull-hold circuit is adopted, new processing such as synchronization with the micro computer is required, and each light-receiving element receives very weak light such as pulsed external light (for example, tree leakage). If there is, there is a high possibility that it will be an intermediate value between 0 and 1 even if it is sufficiently lower than the saturation value after amplification. If this value is held, the microcomputer in the subsequent stage will judge 0 or 1 Uncertainty will be lost due to an unstable phenomenon that occurs. If the monostable multivibrator is used, such instability disappears and the output rectangular wave of the amplifier can be driven at the rising or falling of the rectangular wave and can be held accurately for a certain period of time (1 second in the present embodiment).

[Brief description of drawings]

FIG. 1 is a block diagram of a level sensor according to an embodiment of the present invention, FIG. 2 is a detailed explanatory view of an optical sensor, FIG. 3 is a circuit diagram showing a specific example of the present invention, and FIG. FIG. 5 is an explanatory view of an optical sensor, FIG. 5 is a block diagram of another configuration example of a level sensor using an optical sensor using a plurality of light receiving elements, FIG. 6 is an explanatory view of a conventional level sensor, and FIG. 7 is a conventional level sensor. It is explanatory drawing of the indicator of a sensor. 30 …… Level sensor, 32 …… Optical sensor, 34 …… Light receiving element, 36 _A , 36 _M …… Analog multiplexer, 38 _A , 38 _M …
… Amplifier, 40 _A , 40 _M …… Signal holding circuit, 42 …… Arithmetic control circuit, 60 …… Display device.

Claims (1)

[Claims] 1. An optical sensor comprising a light receiving element array for detecting a light beam from a light source and outputting an electric signal, a capacitor for passing only the intermittent electric signal of each light receiving element, and a multiplexer sequentially after passing through the capacitor. The intermittent electrical signal output by the amplifier that generates a rectangular wave composed of at least three stages of transistors and a saturated output and the edge of the rectangular wave that is generated are captured until a read request is issued from the arithmetic control circuit. A signal holding circuit composed of a monostable multivibrator for holding and a channel selection signal are given to the multiplexer, and holding and reset control is repeated for the signal holding circuit, and a high or low signal holding circuit is used. And a calculation control circuit for sequentially reading the output of the level sensor.