JPS5941521B2 - Laser position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a laser position detection device used, for example, in measuring the deflection of a crane gutter or the like.

[Prior art]

FIG. 1 is a block diagram showing an example of a conventional laser position detection device.

1 and 2 are photoelectric conversion elements such as photodiodes that convert optical signals from the rotating laser beam cross section A into electrical signals, and these photoelectric conversion elements 1 and 2 are arranged close to each other. A photocurrent flows in proportion to the amount of light from the laser beam surface A that is incident on the laser beams 1 and 2.

3.4 is a current-to-voltage conversion circuit that converts the photocurrent from the photoelectric conversion elements 1 and 2 into voltage; 5 and 6 are amplification beads; and 7 is a subtraction circuit. Voltage e1 and voltage E amplified by the amplifier 6
2 (e1-E2) is output as a differential voltage.

This voltage (e1-E2) is proportional to the deviation y between the center line B of the laser beam cross section A and the boundary line C between the photoelectric conversion elements 1 and 2.

8 is a waveform circuit, and this waveform circuit 8 generates a voltage e having an attenuated waveform as shown in FIG. 2 in response to the differential voltage.

Here, e is proportional to (e1-E2).

Further, T indicates the period of the laser beam cross-sectional rotation speed for one rotational force. 9 connects the photoelectric conversion element 1 through a screw mechanism or the like.
The servo motor 9 moves the laser beam 2 vertically according to the magnitude of the voltage e of the attenuation waveform.When the servo motor 9 receives the first laser beam cross section A shown in FIG.
The voltage of the attenuated waveform in b) is used to move the boundary line C of the photoelectric conversion element 1.2 in the direction closer to the center line B of the laser beam cross section A. Then, the second laser beam cross section A is When light is received, it is driven by the voltage of the attenuated type (b).

In this way, the laser beam h-plane A is received by the photoelectric conversion elements 1 and 2 a plurality of times, and when the center line B of the laser beam cross section A almost coincides with the boundary line C of the photoelectric conversion element 1.2, the servo motor 9 is starting to stop. The laser position detector configured as described above has the following problems.

(1) The position of the laser beam cannot be detected unless the photoelectric conversion element receives the cross section of the laser beam multiple times.

(2) It is difficult to determine the voltage magnitude of the attenuated waveform.

In other words, the area (
If the diagonal line (in the figure) is made large, the amount by which the photoelectric conversion elements 1 and 2 will move when the first laser beam portrait A is received will be large, but one-inching will occur near the balance point.
There is a risk of permanent imbalance.

In addition, if the area is made smaller, it will take longer to achieve balance, but due to the friction of the servo motor 9 and other drive systems, the boundary between the center line B of the laser beam h plane A and the photoelectric conversion element 1.2 There is a possibility that the motor will stop at a position that does not completely match line C. (3) Detection accuracy deteriorates due to the reason stated in (2).

(4) Since the servo motor is driven only when the photoelectric conversion element receives a cross section of the laser beam, so-called 0N-0FF control, the detection time becomes long. [Object of the Invention] In view of the above points, it is an object of the present invention to provide a laser position detection device that can detect the center position of the laser beam surface in a short time and with high accuracy regardless of the rotational speed of the laser beam surface. With the goal.

[Summary of the Invention] The feature of the present invention is that by moving two photoelectric conversion elements in the vertical direction by one driving means, the boundary line of 12 photoelectric conversion elements can be moved in the cross section of a laser beam rotating in a horizontal plane. In a laser position detection device that aligns with the center line, once a horizontally rotating laser beam is received by a photoelectric conversion element, two photoelectric conversion elements can be detected even before receiving a second laser beam. The position of the photoelectric conversion element is moved in the vertical direction so that the boundary line of
[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, the same reference numerals as in FIG. 1 indicate the same parts. 10 and 11 convert the output current from the photoelectric conversion element 1.2 into a voltage El. Load resistors 12 and 13 that convert into e2 are AC amplifiers.

14.15 is a maximum value detection circuit that detects the maximum value of the voltages El and e2 that change when the laser beam cross section A rotating in the horizontal plane passes the front surface of the photoelectric conversion elements 1 and 2, and holds the maximum value. .

16 is a first subtraction circuit which calculates the difference between the maximum value Elm of the voltage e1 and the maximum value E2m of the voltage E2.

17 is a potentiometer; this potentiometer 17
The contactor detects the position of the boundary line C while moving in conjunction with the movement of the boundary line C between the photoelectric conversion elements 1 and 2.

18 is an adder circuit that calculates the sum of the output voltage of the first subtraction circuit 16 and the output voltage Ep of the potentiometer 17; 19 is a sample api-hold circuit that temporarily stores the output voltage from the adder circuit 18; The sample amplifier hold circuit 19 puts the output voltage to be stored into a sample or hold state in accordance with the magnitude of the output voltage applied from a comparator circuit to be described later.

20 is the respective output voltage El.20 amplified by the AC amplifier 12.13. an addition circuit that calculates the sum of e2;
Reference numeral 21 denotes a comparison circuit that compares the output voltage added by the addition circuit 20 with a set voltage E that is arbitrarily set in advance. When the output voltage is zero or the output voltage is greater than E, a command signal corresponding to the output voltage of Ec is generated and applied to the sample ambigold circuit 19.

At this time, when the output voltage of the comparator circuit 21 is zero, the sample amplifier circuit 19 is in the Hall P state.
When the output voltage is Ec, it is in a sample state. Reference numeral 22 denotes a delay circuit, and the delay circuit 22 delays the time determined by the constant of the delay circuit after the output voltage Ec of the comparator circuit 21 changes to zero, that is, after the sample amplifier circuit 19 enters the hold state. After a delay of t, a command signal is generated to release the output voltage held by the maximum value detection circuit 14, 15.

23 is a second subtraction circuit that calculates the difference between the output voltage of the sample amplifier circuit 19 and the output voltage of the potentiometer 17, and 24 is an amplifier.

Next, the operation of the laser position detection device configured as described above will be explained.

Photoelectric conversion element 1 converts laser beam cross section A rotating on a horizontal plane
．． 2 receives light, the output currents from the photoelectric conversion elements 1.2 flow through the load resistors 10.11, respectively, and the output voltages El.
It is converted to e2.

This output voltage E, . e2 is received with the center line B of the laser beam surface A shifted by a deviation y from the boundary line C between the photoelectric conversion elements 1 and 2, as shown in FIG. When moving the front from one end to the other,
Its size changes as shown in FIG. 4b. Furthermore, after the output voltages El and e2 are amplified by AC amplifiers 12 and 13, the maximum value is detected by maximum value detection circuits 14 and 15, and this value is held. Here, if these values are respectively Elm and e2m, then Elm. e2m is (1
), (2).

Elm=K1・K2(h/2−y)W ・・・・・・(
1) E2m=K1・K2(h/2+y)W...
・(2) Here, K1: Constant determined by illuminance of laser beam cross section A, characteristics of photoelectric conversion element 1.2, etc. K2: Amplification degree h of AC amplifier 12.13: Height of laser beam cross section A y: deviation between the center line B of the laser beam cross section A and the boundary line C of the photoelectric conversion element 1.2 W: the width of the photoelectric conversion element 1.2; 2 output voltage El. When the difference between the maximum value Elm of e2 and E2m is calculated, equation (3) is obtained.

Elm-E2m=-2K1K2yW... (3
) In equation (3), Kl, K2, and W are constant, so the output voltage of the first subtraction circuit 16 is only the deviation y between the center line B of the laser beam cross section A and the boundary line C between the photoelectric conversion elements 1 and 2. is proportional to.

Next, the output voltage obtained by the first subtraction circuit 16 and the output voltage E of the potentiometer 17 are added by the addition circuit 18, and then the output voltage of this addition circuit 18 is stored in the sample ambihole pin circuit 19. . Next, the timing of sampling or holding the output voltage stored in the sample-and-hold circuit 19 will be described.

FIG. 5a shows the output voltages K and e of the AC amplifiers 12 and 13.
llK2e2 and their respective output voltages K2el,K
The output voltage K2 (e
1+E2), and this added output voltage K2
A comparison circuit 21 compares (e1+E2) with a preset voltage E.

The comparison circuit 21 outputs the added output voltage K2(E, +
When E2) is smaller than the set voltage E, the output voltage is zero, and when the output voltage K2 (e1+E2) is larger than the set voltage E, the output voltage of Ec is applied as a command signal to the sample-and-hole F circuit 19. As shown in FIG. 5b, the circuit 19 enters the Hall P state when the output voltage is zero, and enters the Sample state when the b1 output voltage is Ec. In this way, the sample-and-hold circuit 19 enters the Hall P state from the point in time when the output voltage of the comparator circuit 21 changes from Ec to zero. At this point, the maximum value detection circuits 14 and 15 detect the maximum output voltages Elm and e2m of the photoelectric conversion elements 1 and 2 and hold those values. The sum of the output voltage (e1 to E2m) of the circuit 16 and the output signal Ep of the potentiometer 17 indicating the position of the boundary line C of the photoelectric conversion element 1.2 at this time is stored. Furthermore, after the time t determined by the constant of the delay circuit 22 has elapsed since the data was stored, the output voltages of the maximum value detection circuits 14 and 15 become zero. The sample-and-hole circuit 19
Since the output voltage of is maintained even after the laser beam passes through the photoelectric conversion element 1.2, the circuit in FIG.
The servo motor 9 is driven by 1 so that the output voltage E of the potentiometer 17 becomes equal to this value. Here, the output voltage of the second subtraction circuit 23 is 2K,·K2·WM, which corresponds to the unit length of the deviation y from equation (3), so the output voltage E of the potentiometer 17 is also the unit length of the deviation y. If the displacement of D is set to be equal to -2K1・K2・W (V), the servo motor 9 will be proportional to the displacement even when the laser beam is not incident on the photoelectric conversion element 1.2. The photoelectric conversion element 1 is placed on the center line B of the laser beam bright side A.
, 2 and stop when the boundary line C of 2 coincides with each other. Said (3
As shown in FIG. 6, the constant K1 shown in the equation ) is constant in the range (the linear range shown in the figure) in which the illuminance of the laser beam A and the output current characteristics of the photoelectric conversion element 1.2 are proportional.

However, depending on the brightness around the photoelectric conversion elements 1 and 2 (for example, when sunlight is added to the laser beam), the illuminance of the laser beam bright side A and the output current characteristics of the photoelectric conversion elements 1 and 2 are proportional to each other. In the range where it disappears (non-linear range), K1
changes.

FIG. 7 shows another embodiment of the present invention for eliminating these disadvantages.

In FIG. 7, the same reference numerals as in FIG. 3 indicate the same parts.

25 is an addition circuit that calculates the sum of the maximum value Elm of the output voltage e1 detected by the maximum value detection circuit 14 and the maximum value E2m of the output voltage E2 detected by the maximum value detection circuit 15; is installed in parallel.

26 is the difference voltage (Elm-E2m) of the first subtraction circuit 16 based on the sum voltage (Elm+E2m) of the adder circuit 25.
A signal from this divider circuit 26 is sent to an adder circuit 18.

With the above configuration, the maximum value Elm
The sum of E2m and E2m is calculated, and the division circuit (Elm-E
2m) By 26? -Division by one is performed (Elm+E2m).

As a result of this division, the output voltage of the division circuit 26 is expressed by equation (4). ν115− 1 −Z”− 1 In equation (4), since the portrait height h of the photoelectric conversion element is constant, the output voltage of the dividing circuit 26 is equal to the distance between the center line B of the laser beam cross section A and the photoelectric conversion element. 1.2 is proportional only to the deviation y of the boundary line C.

Here, since the output voltage of the divider circuit 26 is D-1 per unit length of y from equation (4), the output voltage H of the potentiometer 17 is also equal to - for the displacement of unit length per unit length. Naru h
Just set it like this.

With the above configuration, even if the illuminance of the laser beam positive side and the output current characteristics of the photoelectric conversion element are not proportional, for example, when sunlight is added to the laser beam, the laser beam h side A
The center line B of can be detected easily and accurately.

In each of the above embodiments, it is clear that the cross section of the laser beam O may be a circular cross section described as a rectangle, or any other vertically symmetrical cross section.

Moreover, although the case where the first laser beam cross section A is received by the photoelectric conversion elements 1 and 2 has been described, when the second laser beam cross section A is received, the maximum value detection circuit 14
, 15 has been released, the maximum output voltage due to the second laser beam can be easily detected.

〔Effect of the invention〕

As described in detail, in the laser position detection device of the present invention, once the photoelectric conversion element receives the laser beam cross-section rotating in a horizontal plane, the boundary line of the photoelectric conversion element is detected even before the second laser beam cross section is received. Since the servo motor is proportionally controlled so that it moves vertically to match the center line of the laser beam cross section, the center plane of the laser beam cross section can be detected smoothly regardless of the rotation speed of the laser beam h plane. This improves measurement accuracy.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional laser position detection device, Figure 2 is a block diagram of a conventional laser position detection device.
The figure shows the attenuated voltage waveform applied to the servo motor,
FIG. 3 is a block diagram of an embodiment of the laser position detection device of the present invention, FIG. Figure 5a is a diagram showing the change in the magnitude of the output voltage obtained at the output terminal of the photoelectric conversion element when a portrait passes in front of the photoelectric conversion element; Figure 5a is a diagram showing the voltage input to the comparison circuit; Figure b is a diagram showing the output voltage from the comparison circuit, Figure 6 is a diagram showing the relationship between the illuminance of the cross section of the laser beam and the output current of the photoelectric conversion element, and Figure 7 is a diagram showing the relationship between the illuminance of the cross section of the laser beam and the output current of the photoelectric conversion element. FIG. 2 is a block diagram showing an example. 1, 2... photoelectric conversion element, 14, 15...
...Maximum value detection circuit, 16...First subtraction circuit,
17...Potentiometer, 19...
Sample and hold circuit, 21... Comparison circuit, 22... Delay circuit, 23... Second
Subtraction circuit, A... Laser beam cross section, B...
... Center line of the loser beam, C ... Boundary line of the photoelectric conversion element.

Claims (1)

[Claims] 1. By moving two closely spaced photoelectric conversion elements in the vertical direction by a driving means, the boundary line of the photoelectric conversion elements can be set to a cross section of a laser beam rotating in a horizontal plane. A maximum value detection circuit that detects the maximum value of the output voltage of each photoelectric conversion element that converts the position of the laser beam into an electrical signal and holds this value in the laser position detection device that is aligned with the center line. and a first subtraction circuit that calculates the difference between the output voltage of the maximum value detection circuit, and temporarily stores the sum of the output voltage of the first subtraction circuit and the output voltage of a potentiometer that is linked to the movement of the boundary line of the photoelectric conversion element. a sample-and-hold circuit; and a comparison circuit that compares the sum of the output voltages of the respective photoelectric conversion elements with a preset voltage arbitrarily set, and generates a command signal to cause the sample-and-hold circuit to sample or hold. a delay circuit that generates a command signal to release the hold of the maximum value detection circuit after the output voltage of the sample and hold circuit enters the hold state; a second subtraction circuit that calculates a difference, and a driving means that adjusts the output voltage of the second subtraction circuit so that the boundary line of the photoelectric conversion element coincides with the center line of the laser beam cross section regardless of the rotation speed of the laser beam. A laser position detection device characterized by proportionally controlling the 2 By moving two photoelectric conversion elements arranged close to each other in the vertical direction by a driving means, the boundary line of the photoelectric conversion elements is made to coincide with the center line of the cross section of a laser beam rotating in a horizontal plane. In the laser position detection device, the maximum value detection circuit detects the maximum value of each output voltage of the photoelectric conversion element that converts the position of the laser beam into an electric signal, and holds this value, and the maximum value detection circuit a first subtraction circuit that calculates the difference between the output voltages of the maximum value detection circuit; an addition circuit that is provided in parallel with the first calculation circuit and calculates the sum of the output voltages of the maximum value detection circuit; A division circuit that divides the differential voltage of the 1-subtraction circuit, and a sample-and-hold circuit that temporarily records the sum of the output voltage of this division circuit and the output voltage of a potentiometer that is linked to the movement of the boundary line of the photoelectric conversion element. and a comparison circuit that compares the sum of the output voltages of the respective photoelectric conversion elements with a preset voltage set arbitrarily, and generates a command signal to cause the sample-and-hold circuit to sample or hold; After the output voltage of the and-hold circuit enters the hold state, a delay circuit generates a command signal to release the hold of the maximum load detection circuit, and a difference between the output voltage of the sample-and-hold circuit and the output voltage of the potentiometer is calculated. The driving means is proportionally controlled according to the output voltage of the second subtraction circuit so that the boundary line of the photoelectric conversion element coincides with the center line of the laser beam cross section regardless of the rotation speed of the laser beam. 1. A laser position detection device characterized in that: