JPH03185309A - Level sensor - Google Patents

Abstract

PURPOSE:To reduce the number of processes of level measurement and to facilitate the measurement by a method wherein detection signals of a plurality of light-sensing elements constituting a level sensor are inputted sequentially to signal hold circuits from multiplexers and held therein temporarily until an arithmetic control circuit reads them. CONSTITUTION:A light beam from a light source rotates at a prescribed period on a horizontal plane. A light sensor 32 constituting a level sensor is constructed of a plurality of light-sensing elements 34 and only the light-sensing element 34 on which the light beam strikes outputs an electric signal. Receiving a channel selection signal from an arithmetic control circuit 42, multiplexers 36A to 36M to which light-sensing elements 34 are connected respectively output detection signals of the light-sensing elements 34 sequentially and input them to signal hold circuits 40A to 40M. The signal hold circuits 40 hold temporarily the signals inputted from the multiplexers 36 until the arithmetic control circuit 42 reads them, and based on the detection signal of each of the light-sensing elements 34, a position at which the light beam traverses the light sensor 32 is computed. Accordingly, the height of the light source and the level sensor and the degree thereof can be judged with ease.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a level sensor that determines the height between two points in surveying, and in particular, a level sensor that detects a level sensor that determines the height between two points in surveying. , relates to a level sensor that compares the height (level) with a laser light source.

[Conventional technology]

In recent years, when leveling between two points, a laser light source is 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 is sometimes used at the other point.

A conventional level sensor of this type is as shown in FIG.

In Figure 6, the level sensor! One surface of O is a light-receiving surface 12, and a vertically elongated rectangular light-receiving section 14 is provided on this light-receiving surface 12. In front of the light receiving surface 12,
A laser light source (not shown) is installed, and the laser light 16 rotates at a constant period in a horizontal plane as shown by an arrow 18.

In addition, the level sensor IO includes an 0 display 20 provided with a display 20 made of liquid crystal on a surface different from the light receiving surface 12.
As shown in FIG.
An upward arrow 22 that displays an instruction to move the level sensor upward when passing above the vertical center of 4.
, a bar 24 indicating that the laser beam 16 has passed through the vertical center of the light receiving section 14 , an instruction to move the level sensor downward when the laser beam 16 has passed below the vertical center of the light receiving section 14 It consists of a downward arrow 26 that displays .

(Problem to be Solved by the Invention) However, in the conventional level sensor 10 described above, the level can only be determined when the laser beam 16 crosses the center of the light receiving section 14 in the vertical direction. When measuring the level, it is necessary to move the level sensor up and down to align it with the correct position so that it passes through the vertical center of the light receiving section 14, which not only makes the work complicated, but also
It requires a lot of time. For this reason, when creating land with many uneven surfaces, it is necessary to use level sensors frequently when excavating the upper ground, which increases the number of man-hours required for level measurement and also increases the amount of time required for measurement. This is a factor that hinders the speedy progress of construction because it takes time.

The present invention has been made in order to eliminate the drawbacks of the prior art, and aims to provide a level sensor that can reduce the number of steps required for level measurement and that can easily measure the level.

[Means to solve the problem]

In order to achieve the above object, the level sensor according to the present invention includes an optical sensor consisting of an array of light receiving elements that detects light rays from a light source and outputs electricity No. 48, and each of the above-mentioned light receiving elements of the sensor is connected. , a multiplexer that sequentially outputs the detection signal of each light receiving element, a signal holding circuit that temporarily holds the signal output by the multiplexer, and a channel selection signal that is applied to the multiplexer and held by the signal holding circuit. It is characterized by comprising an arithmetic control circuit that reads a signal and determines the position of the light beam on the optical sensor.

[Effect]

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

Therefore, the height and degree of height between the light source and the level sensor can be easily determined, the number of man-hours required for level measurement is reduced, level measurement can be performed easily and quickly, and construction work such as land reclamation can be promoted. .

[Embodiments] Preferred embodiments 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 will be described in detail later. Each light receiving element 34 has one terminal connected to a DC power supply, and the other terminal connected to ground via a load resistor R1, and is connected to an analog multiplexer (hereinafter referred to as (simply referred to as multiplexer) 36. It is connected to the input terminal of ~36,
When a light beam such as a laser beam is incident, an electric signal is sent to a multiplexer 36. Enter ~36M.

Multiplexers 36A-36. has one output terminal S and 8 or 16 input terminals (channels), and a light receiving element 34 is connected to each input terminal via a coupling capacitor Cc.

and each multiplexer 36. The output terminal S of 3611 is connected to an amplifier 38 . ~38. Connect to the input terminal of Also, the multiplexer 36. It receives a channel selection signal from an arithmetic control circuit 42 consisting of a ~36NL microcomputer, and the connection of each input terminal to the output terminal S is sequentially switched by the channel selection signal from the arithmetic control circuit 42. The output signal of the light receiving element 34 connected to each input terminal is sequentially input to the amplifiers 3B, .about.38.

The output side of the amplifiers 3B, -3B, is connected to a signal holding circuit 40, -40.
is connected to the input terminal of multiplexer 36. ~36
．． The signals outputted by the signal holding circuits 404 to 40 . are amplified and waveform shaped. Enter. Each signal holding circuit 404-4
0M are amplifiers 3B, to 38. When a signal is input from I, the signal is held for a predetermined period of time, and upon receiving successive signals from the arithmetic control circuit 42, the held signals are simultaneously output to the arithmetic control circuit 42. The arithmetic control circuit 42 calculates and determines which position of the light receiving element 34, that is, the optical sensor 32, where the light beam has passed, based on the signals manually input from each signal holding circuit 40A to 40H, and calculates the result of the calculation. is output to the display device 60 and displayed.

As shown in FIG. 2, the optical sensor 32 includes a plurality of light receiving elements 34. It consists of ~34H. Each light receiving element 34A~
34. 1 is formed into a rectangular parallelepiped shape, each having a length l, a radius b, and a thickness t, for example, and are brought into contact with each other in a line so that the width direction is the height (length) direction of the optical sensor 32. Placed. Each of the light-receiving elements 341 to 34N has a photosensitive section 44 at its center in the length direction, and electrode sections 46 and 48 are formed at both ends of the photosensitive section 44.

The light-receiving elements 34a to 34N need only have a size that allows them to detect light beams, and those having a length l of several mm (for example, 5 mm) and a width of 1 mm can be used. If it is desired to increase the accuracy of the level sensor 30, it is desirable to make the width of the light receiving element 34 1 mm or less, but if the tolerance is on the order of several mm, a 1 mm wide element is sufficient. The light receiving element 34 is a device such as a photodiode, a phototransistor, a photodarlington transistor, etc. that converts an optical signal into an electrical signal, and it does not matter whether it is crystalline or non-crystalline.

The length h of the optical sensor 32 is desirably several tens of mm or more, preferably 80 mm or more, and a sufficient length is 160 mm.
That's all.

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

A light beam (laser light) from a light source (not shown) rotates with a predetermined period. Then, the level sensor 30 is
When the power is turned on, the arithmetic control circuit 42 is activated and sends a channel selection signal to the multiplexers 36A to 36° in synchronization with a fixed period, for example, the rotation period of the laser beam.

Each multiplexer 36^~36. is the arithmetic control circuit 42
When the first channel selection signal is input from
The th input terminal and the output terminal S are turned on, and the detection signal from the light receiving element 34 connected to the tt input terminal is sent to the amplifiers 38a to 38M.

Each amplifier 38a-38. is multiplexer 36A~3
6. The detection signal of the light-receiving element 34 outputted by the light receiving element 34 is amplified and waveform-shaped, and the output signal of the light-receiving element 34 hit by the light beam becomes "H".
” (high), and the output signal of the light-receiving element 34 that is not hit by the light beam is set as “L” (low) and the signal holding circuit 40a~
Send to 40e.

The signal holding circuits 40a to 4ON hold the signals for a certain period of time so that the arithmetic control circuit 42 can take in the signals output from the amplifiers 3B and 3BM. This signal holding circuit 40A
The retention of the signal by ~40.4 is due to the following reason.

Since the light beam emitted from the light source rotates with a predetermined period, the time it takes for the light beam to cross the optical sensor 32 is extremely short, and a certain light receiving element 34. Even if a light beam is incident on the multiplexers 36A to 36. must wait until the detection signal arrives from the light-receiving element 34, and the arithmetic control circuit 42 determines whether the light beam has entered the light-receiving element 34 (the signal held by the signal holding circuits 40. to 40. This is because it is necessary to hold the signal until it is determined whether the signal is rH or "L".

That is, the light beam generally rotates at a period of about 0.1 seconds to 1 second. Therefore, the time it takes for the light beam to cross the optical sensor 32 during one turn is several p seconds, assuming that the distance between the level sensor 30 and the light source is 100 m. For this reason, the multiplexers 36A to 36H are connected to the selected channel so that when the light beam hits the light receiving element 34, the detection signal of the light receiving element 34 is input to the amplification 33B, so that the light beam crosses the optical sensor 32. Until, that is, 0.
It is necessary to turn on the channel where the song is selected for about 1 second to 1 second. Moreover, the light beam detection signal of the light receiving element 34 that is amplified by the amplifier 38 is several microseconds long, and the arithmetic control circuit 42
can determine whether the light beam has entered the light receiving element 34 or not.
This is because it is necessary to hold the signal output by the light receiving element 34 for about 1 second to 1 second.

Each of the signal holding circuits 404 to 40M receives successive signals from the arithmetic control circuit 42 and simultaneously sends out the held signals to the arithmetic control circuit 42. The fA calculation control circuit IPI42 is connected to the signal holding circuits 40A to 40. When a signal is received from the signal holding circuit 40A to 4ON, a clear signal is sent to the signal holding circuits 40A to 4ON to clear the held signal. Then, the arithmetic control circuit 42 includes the signal holding circuits 40, to 40 . The level rHJ, "L" of the signal inputted from is checked, and the result is stored in a memory (not shown) in correspondence with the light receiving element.

Further, the arithmetic control circuit 42 includes signal holding circuits 40A to 40
At the same time as sending a clear signal to M, multiplexer 3 (I
Channel selection signals are sent to the multiplexers 36A to 36.A to 36D. The first input terminal and output terminal S are turned off, the second input terminal and output terminal S are turned on, and the light receiving element 3 is connected to the second input terminal.
The detection signal of 4 is sent to the amplifier 38. ~38. input to l.

Thereafter, the multiplexer 36. After reading the state of the output signal of the light receiving element 34 connected to the last input terminal of ~367, check whether the light beam hits the optical sensor 32 or not.
The position through which the light beam of the optical sensor 32 passes, the diameter of the optical beam, the distance from the center of the optical sensor 32 to the position through which the light beam passes, etc. are determined and output to the display device 60 for display.

In this way, the level sensor 30 of the embodiment has the optical sensor 3
Since the position through which the light beam above 2 passes is determined and displayed on the display device 60, the position of the optical sensor 32 where the light beam hits can be immediately read, reducing the number of steps required for level measurement and making the measurement easy and quick. . As a result, the number of man-hours required for construction work such as land preparation can be reduced, and construction work can be promoted.

Moreover, not only can you instantly know how far the passing position of the light beam is from the center of the optical sensor 32 in the vertical direction, but you can also select any light receiving element 34 of the optical sensor 32 by 5t1! It is also possible to find the passing position of a point ray. Further, the diameter of the light beam can be determined from the number of light receiving elements 34 that are hit by the light beam, and it can be determined whether the size of the light beam is within a normal range. Then, depending on whether the light beam hits the light receiving element 34 on the rooftop or the lowest level, it can be determined whether the light beam is projecting from the optical sensor 32 or not.

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

In FIG. 3, in the optical sensor 32, the light receiving element 34 is composed of a photodiode D. As shown in FIG. 4, there are ten photodiodes D on one chip 50. The optical sensor 32 includes 16 chips 50 arranged in a row and 160 photodiodes D1 to D0.
It depends on ゜.

Each chip 50 has boron diffused as a P-type into an N-type single crystal silicon substrate 52, and ten photodiodes D+''-D+e made of PN junctions are arranged at equal intervals. has a width of 4 mm, and the distance from the center of the first photodiode D to the center of the tenth photodiode D is 10 mm.

Photodiodes D1 to D constituting the optical sensor 32
1, the cathode side is connected to the power supply V, and the anode side is connected to the load resistance 1'? t+~Rt+i. to ground through coupling capacitors CCI-C1,. via multiplexer 36. ~361. Input terminals 11N-B of
'IN, and a reverse bias voltage of, for example, 3V is applied.

Multiplexer 361-36□. has eight channels with eight input terminals, and output terminals OUT are connected to each multiplexer 36t to 36. . Amplifiers 381~ provided corresponding to
38! . Connect to the input of

Also, the multiplexer 36. ~36□. Does level converter A, B, C, and E consist of a microcomputer? * IX ill ill Connected once to the IPI 42, and receives a channel selection signal and an inhibit signal for turning off all channels from the arithmetic control circuit 42.

Each amplifier 381-38. . As shown in the example of the amplifier 381, the base of the PNP transistor TR is connected to the multiplexer via a coupling capacitor C1 that cuts the DC component. Also, the transistor T I? +
The base of is connected to the circuit power supply VCC via resistors R, , R, and grounded via resistors Rz, Rq. Note that a capacitor C2 is connected in parallel to the resistor R. Further, the resistors R+, Rz, Rs, and R9 are adjusted so that the transistor TR is turned on when the input to the base is 1 OmV or less.

The emitter of the transistor TR is connected to the power supply VCC, and the collector is grounded via a resistor R4, and is connected to the NPN transistor TR via a coupling capacitor C1 that cuts DC.

The output signal generated at the collector is connected to the base of the transistor TR.

The base of the transistor TR is connected to the power supply VCC via a resistor R2, and is grounded via a bypass capacitor C1 connected in parallel to resistors R6, R1, and R1. Bypass capacitor C4 removes the AC noise component of the signal input to the base of transistor TR. Further, the collector of the transistor TRt is connected to the power supply VCC via the resistor R1, and the collector is connected to the power supply VCC through the resistor R1.
It is connected to the base of a PN type transistor TR, and outputs the output signal of the transistor TR to the base of the transistor TR3. The emitter of the transistor 'rR2' is grounded via a resistor R9. However, the resistance values of the resistors Re and Rw are selected so that Rs ) R*.

The collector of the transistor TR, serves as the output terminal of the amplifier 38, and is connected to the power supply vec via the resistor R111, as well as to the input terminal A of the signal holding circuit 40, and the output appearing at the collector The signal can be input manually to the signal holding circuit 40. Further, the eco-tail of the transistor TR is grounded.

Signal holding circuit 40. ~402. consists of a monostable multi-bi break, and each signal holding circuit 40. ~40t, timing resistor R□~ for adjusting the pulse width outputted by
R1, and timing capacitor C? I to cyze are externally attached. Further, the signal holding circuit 40. ~407. The output terminal Q of the arithmetic control circuit 42 is the input terminal INI~l
N2O, and the signal holding circuits 404-40. I
This allows the signals held by the controller to be input manually to the arithmetic control circuit 42. A display device 60 made of, for example, a liquid crystal element is connected to the output side of the arithmetic control circuit 42.

When the power of the level sensor 30 is turned on, the arithmetic control circuit 42 operates the terminals A, B of the multiplexers 361 to 36t.
A channel selection signal is sent to C, and each multiplexer 3
61-36. . The first input terminal 11N of the output terminal O
Connect to UT. As a result, the photodiodes D1, D9, Dll, --- connected to each input terminal 11N
--D +s 3 detection signal is coupling capacitor CCI,
CC4, CC1? , --... Multiplexers 361 to 36□ via CC153.

and multiplexer 36. ~36. . to amplifier 38. ~38. . is output to.

Amplifier 38. ~38. . is multiplexer 361-3
6□. When no signal is input from the photodiode D (when no light beam hits the photodiode D), rHJ is output.

That is, multiplexer 36. ~36. . If No. 4g does not come in from amplifier 38. ~38. .

Transistor TR, has a low base voltage and is in an on state because the base current flows through R, , R9. Further, since the transistor TR- is on, the transistor TR is in an on state because the output of the transistor TR is applied to the base, and a current flows from the collector to the emitter. The collector resistance R1 and emitter resistance R9 of the transistor TR1 are R1)R as described above.
.

Therefore, the collector voltage decreases due to the voltage drop caused by the resistor R8. For this reason, the transistor T R
, is in the off state due to the low base voltage. Therefore, amplifier 38. ~38□. The collector voltage of the transistor "rR" which is the output of is the power supply voltage ■., and the signal holding circuits 401 to 40□.

rH, is input manually to input terminal A of. Then, the signal holding circuits 40A to 40 output LJ.

When the photodiode D is hit by a light beam, the δ holding circuits 40+ to 40□ correspond to the photodiode D hit by the light beam. The output of is held at rHJ for a predetermined time.

In other words, a reverse bias voltage is applied to the photodiode D, and when a light beam hits the photodiode D, a photocurrent flows, and at least 1
A voltage of 0 mV or more is applied to the amplifier 38 via the viscous capacitor Ct and the multiplexer 36. This input signal is applied to the transistor TR via a coupling capacitor C1.

is applied to the base of transistor TR, increasing the base voltage of transistor TR. Therefore, the transistor TR1 turns off, and the transistor TR1 turns off.

The it current flowing to the emitter of is reduced. Therefore, the voltage drop across the resistor R4 of the transistor TR becomes smaller and the emitter voltage decreases, and this voltage drop is transmitted to the base of the transistor TR via the coupling capacitor C8, and the base of the transistor TR. The voltage is lowered to turn off transistor TR2. When the transistor TRx is turned off, the collector voltage of the transistor TRff1 increases. Since the collector of transistor TR3 is directly connected to this collector, transistor 1
” When the collector voltage of R1 increases, the transistor T
R1 immediately turns on and becomes saturated. Therefore, the collector voltage of the transistor TRI becomes almost the ground voltage,
Signal holding circuit 40. ~40. . The outputs of the amplifiers 381 to 38t connected to the terminal A change from rH to "L".

Signal holding circuit 40. ~40. . When the human power of the signal holding circuit 40 changes to "L", the signal holding circuit 40. ~40ffi. is triggered, and the output of the signal holding circuits 406 to 40M is r II
J, and this rH is held for a predetermined time depending on the product of the tie-matching resistor RT and the timing capacitor Ct. It is desirable that the time for holding this rH, be longer than the rotation period of the light beam, for example, if the rotation period of the light beam is 0.
．． When the holding time is 2 seconds, the holding time is set to 1 second.

lti? ! The $ control circuit 42 is a signal holding circuit 40□~
A read signal is applied to each signal holding circuit 40. ~4
0,. Read the signal output by and check whether it is "■1" or "
L” and send the result to the photodiode D.
1, D9, Do, ""-"' D Is 3 and stored in the memory. When the data storage is completed, the arithmetic control circuit 42 stores each signal in order to prevent interference with the next signal. A clear signal is manually applied to the terminal E of the holding circuits 40+ to 40.. to clear the signals held by the signal holding circuits 40 to 40.., and also to the multiplexer 36.
~36□. A channel selection signal is sent to turn off the 11N terminal and turn on the 21N terminal. The sending period of this channel selection signal is synchronized with the turning period of the light beam.

Multiplexer 36. ~36□. channel is 11N
When switched from to 21N, the photodiode Dz
, D+. , D4, -m-・I)+sa output signal is connected to coupling capacitor CCX, cc+e, c+s-・-Cl54
and multiplexers 361-36! , and amplification 53 through
8. ~381. Enter.

The arithmetic control circuit 42 similarly operates the multiplexers 361 to 36! . The output signals of the photodiodes connected to all 8IN terminals of the sensor are checked and stored in the memory, and the position on the optical sensor 32 through which the light beam passes is calculated.

As in this embodiment, the 8-bit multiplexers 36, .
36□. When 1 is used, the photodiode D I-D
It takes eight times the rotation period of the light beam to take in all the output signals of L6 # to the arithmetic control circuit 42,
For example, when the rotation period of the light beam is 0.2 seconds, the calculation control j
It will take 1.6 seconds for n[1li1B42 to capture the output of photodiodes D, ~D4°.

The beams generally range in diameter from 5 to 40 mm. Therefore, when the light beam crosses the optical sensor 32, a plurality of photodiodes receive the light beam, and the memory of the arithmetic control circuit 42 has the following information:
The detection signal of the photodiode D hit by the light beam is rH,
The detection signal of the photodiode D that was not hit by the light beam is stored as "LJ".Therefore, the arithmetic control circuit 42 stores the detection signal of the photodiode D that was hit by the light beam from the data stored in the memory. The position of the light beam is calculated, the median value is calculated, and the result is output to the display device 60 as the position where the light beam passes through the optical sensor 32 and displayed. indicate.

Further, the arithmetic control circuit 42 calculates the number of photodiodes that are hit by the light beam, and when the number is 40 or more or 5 or less, displays that on the display device 60,
Informs you that there may be a problem with the light source. Furthermore, when the dog sensor 32 is not hit by the light beam, the arithmetic control circuit 42 displays a message to that effect. Then, when the light beam hits the top photodiode D1 or the bottom photodiode D1611, the arithmetic control circuit 42 determines that the light beam may extend from the optical sensor 32. ``Measurement not possible J'' is displayed, and when the light beam hits the top photodiode D, an instruction to raise the level sensor 30 is displayed, and the bottom photodiode D1.

When the light beam hits the level sensor 30, a display instructing the level sensor 30 to be lowered is displayed.

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

(Margin below) Note that □ indicates that measurement is not possible.

As described above, the measurement by the Reher sensor of the example has an error within ±1 mm, and can be sufficiently put to practical use.

In addition, as shown in FIG. 5, the light receiving elements 34a to 34N
The output signal of
A~388 is directly amplified manually, and amplifiers 3B, ~3B
The output of signal holding circuits 401 to 40. The signal holding circuits 40a to 40. The output of 1 can be manually input to the arithmetic control circuit 42 via multiplexers (including digital multiplexers) 62^ to 62.4. However, in this case, it is necessary to provide an amplifier 38, a signal holding circuit 40, etc. for each of the light receiving elements 34A to 34N, which not only complicates the circuit but also makes it uneconomical.

In addition, in the embodiment, the light source and the level sensor 30
We have described measurement when the light source and level sensor 30 are at approximately the same height (level), but if the emission angle of the light source's light beam can be adjusted, it will also be possible to measure when the light source and the level sensor 30 are at different heights. Can be applied.

[Effect of the Invention J As explained above, according to the present invention, the optical sensor is configured by a row of light receiving elements, the detection signal of the light receiving element is temporarily held by a signal holding circuit, and the output signal of this signal holding circuit is Since the position of the light-receiving element that receives the light beam is determined by inputting it into the arithmetic control circuit, the level relative to the light source can be easily determined, and construction work such as land reclamation can proceed quickly.

[Brief explanation 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 diagram of an optical sensor, FIG. 3 is a circuit diagram showing a specific example of the present invention, and FIG. 4 is a block diagram of a level sensor according to an embodiment of the present invention. An explanatory diagram 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 diagram of a conventional level sensor, and Fig. 7 is a diagram of a conventional level sensor. It is an explanatory view of a display. 30---Reher sensor, 32-light sensor, 3,'! −
--Photodetector, 36A, 36.1 ---Analog multiplexer, 38A, 38m-Amplifier, 4oa, 40
．． --Signal holding circuit, 42- Arithmetic control circuit, 6〇
-Display device.

Claims (1)

[Claims] (1) An optical sensor consisting of a row of light receiving elements that detects light from a light source and outputs an electrical signal, and a multiplexer to which each of the light receiving elements of this optical sensor is connected and sequentially outputs the detection signal of each light receiving element. , a signal holding circuit that temporarily holds the signal output by the multiplexer; and a signal holding circuit that provides a channel selection signal to the multiplexer, reads the signal held by the signal holding circuit, and determines the position of the light beam on the optical sensor. A level sensor comprising: an arithmetic control circuit for determining .