JPS59180475A - Reflection type photoelectric switch - Google Patents

Abstract

PURPOSE:To enable the prevention of malfunctioning due to an object with a large light reflectivity by determining whether an object to be detected exists within a specified detection area to control an output circuit depending on a position detecting means which outputs a position signal corresponding to the position of a focusing spot arranged on a focusing surface. CONSTITUTION:Light from a projection element 12 is reflected with a half mirror 13 and a light beam P formed with a condenser lens 3a projected on an object X to be detected. A light R reflected from the object X being detected is received with the condenser lens 3a, focused passing through the half mirror 13 and reaches a focusing spot S on a PSD20 through a relay lens 3c. Thus, it is determined whether the object X to be detected exists or not within a specified detection area DE to control an output circuit 6 based on the output of a position detecting means 4.

Description

[Detailed Description of the Invention] [Technical Field] "Kibari 1" relates to a reflective photoelectric switch that determines whether a detected object exists within a preset detection area and controls an output circuit. [Background technology 1 Conventionally, as shown in Fig. 1, a reflective light heavy switch in this building uses diffused light emitted from a light projecting means (1)'.
The light receiving means (
2) The light is received by the light receiving means t21 as shown in FIG.
''s received light output level ■ is the preset operating level vt
There is a diffuse reflection type that sets a detection area (DE) by activating an output circuit when the temperature is higher than h. However, in such a conventional example, as shown in FIG. When the detection area (DE) is set according to the width of the belt conveyor (BC),
If there is an object (Z) with a higher light reflectance than the detected object behind the detection area (DE) (for example, a mirror plate such as a stainless steel plate), a malfunction may occur.

That is, the light receiving output level V2Vi of the light receiving means (2)'
It is directly proportional to the light reflectance of the detected object flash, and the distance (
Since it is inversely proportional to the degree of drowning, in order to set the detection area (DE)', it is sufficient to set the operation level vth of the discrimination control means by considering all of the above-mentioned light reflectance and distance (4). Detection area (DE) set in this way
An object with a higher light reflectance than the detected object 00 is behind the
If the object (Z) exists, the received light output level V2 when the reflected light (g)y by this object (Z) K is received. )
The light received by
There was a problem that it was often mistakenly recognized as if it existed in DE). In the figure, 02) is a light emitting element such as a light emitting diode, (141' is a light emitting optical system, 0 is a light receiving element such as a phototransistor, photodiode, solar cell, CdS, etc., and (31 is a light receiving optical system) It is.
□On the other hand, in order to completely eliminate such problems, as shown in Fig. 4, the area where the projected beam A from the projecting means (1)' and the received light beam B of the light receiving means (phantom') overlap is Set the detection area (DE), output the light received by the light receiving means (2)', and turn on the bell.
As shown in FIG. 5, there is a limited repulsion type which is provided with a discrimination control means (not shown) that operates in a preset manner and operates all the output circuits when the voltage Vth is greater than or equal to the level Vth.

However, in such a conventional example, in order to set the detection area (DE), it is necessary to mechanically adjust the optical system of the light emitting and receiving means (ge (2)'. ), the setting work is troublesome when accurately setting the sensor.Furthermore, as shown in Fig. 6, for example, if the object to be detected (X) is moved closer to the reflective photoelectric switch ( and the preset distance @
(3s) In other words, when you want to stop the movement of the detected object (3) at the rear end of the detection area (DE), the difference in the light reflectance of the detected object (3) causes the detection area (D
Since E) is different, there is a problem that the stopping position is shifted. In other words, since the detection area (DE) is set based on the level of the reflected light (g) from the detected object (3),
The detection area (DE) is determined by the light reflectance of the object to be detected (3).
) would change.

[Purpose of the invention]

The present invention has been made in view of the above points, and is capable of preventing malfunctions caused by objects with high light reflectance existing behind the light area, and also enables the detection area to be fixed regardless of the light reflectance of the object to be detected. The object of the present invention is to provide a reflective photoelectric switch that allows for easy setting of the detection area.

[Disclosure of the invention]

(Example 1) Figures 7 to 10 show examples of the present invention.
1) is a light projection means for projecting a light beam CP consisting of pulse modulated light onto the object to be detected (3), and an oscillation circuit (10) that generates a synchronized signal to set the light projection tie. , a drive circuit (11), a light emitting element 0'lJ such as a light emitting diode or a laser diode, a half mirror 03), and a light emitting element (a condenser lens (3) to be described later).
It consists of a light projection optical system consisting of a) and an optical system for light emitting light. (2) is the light peak t caused by the detected object (a),
A condensing lens (3a) that condenses the reflected light (P), a wedge-shaped rhythm (3b) serving as an optical path bending means that bends the optical path so as to shift the condensing point from the optical axis, and a condensing point It is a condensing means consisting of a laser beam (3c) that is moved to an appropriate position, and the wedge-shaped prism (3b) condenses the reflected light from the object to be detected in the detection area (DE). It is arranged in the vicinity of the condensing point where the light is condensed by the near J (3a). Note that instead of the wedge-shaped rhythm (3c), the optical path bending means may be formed using parallel plane glass, a diffraction grating, a mirror, a part of a lens, or the like. (41 is a position detection means for detecting the position of the condensing spot (S) condensed by the condensing means (2), and the condensing spot (S)
Outputs a position signal corresponding to the position of . In the first embodiment, a position detecting element (abbreviated as PSD f20) as shown in FIG. 9 is used as the position detecting means (4).
The PSD 120) is a flat silicon plate (with a PIN (31a) on the front surface, an N layer (, 51b) on the back side, and one layer (: 51c) in the middle), and a light-converging spot. The output current LA%lB corresponding to the position (S) is output.
), in which (Pi) is a current source, (
Do) is the ideal diode, (Co) is the junction capacitance, (R
t) is the parallel resistance, and (Ro) is the inter-electrode resistance. (5i
is the discrimination control means, and the output of the position detection means (4) indicates that the object 91+object (3) is detected in the fixed detection area (DE).
), and the output circuit (6) is fully controlled. This discrimination? b control means t5
ji', output box from PSD shiO), stream 11A, I
B full reconnaissance this 1 pressure VA, increase to rl> converting light receiving circuit (2]-a) (21b), logarithmic amplification circuit (22a)
(22b) and logarithmic amplification circuit (22a) output -gnVA
From the logarithm, the subtraction circuit power to reduce the output power nVB of the amplification circuit (22b); and the output of the subtraction circuit (23), , e n V
A/V B is the detection area setting volume (V R')
A comparator circuit that outputs an H level when the preset range is set in By sampling the output of the comparison circuit (24) in synchronization with the synchronization signal), the flash of the object to be detected is detected in the detection area (
The signal processing circuit (2) is formed with a signal processing circuit (2) that can reliably determine whether or not it exists in the DE).
5) The output controls an output circuit (6) consisting of a relay for load control, a semiconductor switch element for load control, etc. Note that the light receiving circuits (21a) (21b
) is a bandpass filter circuit that passes only pulsed optical signals and cuts DC optical signals, or passes only specific frequencies.

(One piece of Example 1) Now, the light from the light emitting element +121 is a half mirror -θ3)
The light beam (P) that is reflected and condensed by the 7th lens (convex a) is projected onto the object to be detected (3), and the light beam reflected by the object to be detected (3) (R) The light is received by the focused beam 'j, (, 3a) and sent to the half mirror 03.
) The light is completely transmitted and concentrated. In this example, when the detected object (3) is located at a distance ib, which is approximately the center of the detection area (DE) as shown in FIG. 11(b), the reflected light from the detected object (3) The condensing point ViQb is formed by the condensing lens (3a) of 100m), and the optical path is not bent by the wedge prism (3b), and the condensing spot (S) on the PSDC 20) is The center position is point Q'b on the optical axis, and the output current I of PSD (Incorporated)
IBI-i will be approximately equal. Next, when the detected object (3) approaches at a distance wi-eat as shown in Figure (a), the focal point of the condensing lens (convex a) should originally be Qa'', but The optical path is bent by the shaped prism (3b) and becomes Qa, and the center position of the condensed spot (S) on PSD (20) via the relay lens (3c) becomes point 013.Therefore, PSD (20) The ratio of the output currents IA and 1B (IA/IB) #″i1 becomes larger, and becomes larger as the detected object (3) approaches. Here, the detected object (distance to force - ea,
The relationship between the deviation ΔX of the focal point Qa' from the optical axis is as follows. In other words, from the condensing point (3a) to the condensing point (Q
a) That is, the distance at (Qa') 1 is ya, the distance from the condenser lens (3a) to the wedge-shaped prism (3b) is yb, and the distance from the wedge-shaped prism (3b) to the condensing point (Qa)t
If the focal length of (3a) is f, then -&a-i is obtained. Next, the apex angle of the wedge-shaped prism (convex b) is θ,
(refractive index k n % The degree of bending of the optical path, that is, the deflection angle is δ
The deviation is δ·(n −1′)θ··········■, and the deviation between the optical axes ΔX and Δz” yc·δ is as follows.

As is clear from the equation (艷), it can be seen that the deviation of the focal point Qa from the optical axis is a function of the distance ΔxVi distance−ea.

In other words, is the distance ff1a at the detected object (3) the deviation Δχ from the optical axis of the focal point (Qa)? It can be detected by detecting it. A play, Aoba Kushi H mountain connection ← L Kashimu 5) - is nothing, U-, Ma-de (-, Na-o, Figure 12 is the PSD (A)) Focusing spot (S) 'lr shows.

On the other hand, when the detected object flash moves away to a distance & as shown in the same figure (c), the focal point by the condensing lens 'j, (sa) will originally be Qc. However, the optical path is bent by the wedge prism (3b) to become Qc, and the center position of the condensed spot <8) on PSDmi via the relay lens (3C) becomes point Q01. Therefore, the ratio (Δ/I)t) of the output currents IA and IB of the PSD 20) becomes smaller than 1, and the farther away the detected object flash is, the smaller it becomes.

As described above, when the distance to the object to be detected (g) changes, the focal point by /z (3a) moves in the direction of the light beam force and the wedge'-shaped prism (3b) The degree of bending of the optical path (deflection angle δ) changes, and the PSD Okagami focal spot (S) moves in accordance with the distance 1'1iF-13. Logarithm value 13 of the ratio CIA/IF) of the output currents IA and IB of the PSD SH0) according to the position h' of the focused spot (S)
Based on n(IA/IB), the force, force, and total force of the object to be detected (X) existing within the detection area (DE) is determined, and the output circuit (6) is controlled 1. In this case, the detection area (DE) is set regardless of the level of the reflected light (R) from the detected object (3), so
It is possible to prevent malfunctions due to objects with high light reflectivity that exist behind the detection area (DE), and also allows the detection area < DE) to be set regardless of the light reflectance of the detected object. (Convex a), half-three-θ islands, etc. are not affected by contamination of the light emitting/receiving optical system.

(Example 2) The 13th item 1 shows another example, and the 8th item described by AfJ
Logarithmic amplification circuit (22a) (22) of figure discrimination control means (6)
In place of b), if an addition circuit and a subtraction circuit (33) are provided, a division circuit (□□□) is provided in place of the subtraction circuit. 33) And in the comparison circuit example, there is a detected object (
3) exists, and the overall configuration and operation are exactly the same as in the first embodiment described above.

As mentioned above, in the first invention, the light projecting means +11
A light beam (■) is projected onto the object to be detected (X) from a force, and by directing the reflected light (■) of the light beam (P) by the sensing object (3), the object to be detected is (X) Distance at age ^, j
, 13. Now, the position of this focusing spot (S) is detected by the position detecting means (4), and the position II! Based on the output of the detection means (4), the discrimination control means f5i determines whether the rose detection object (X) is in a predetermined detection area (
Since the detection area (DE) determines whether the detected object (X
) The detection area (DE) can be set regardless of the light reflectance of the detection area (DE). ) is set to a positive ζ ", the setting work becomes easier. In the above-mentioned Example 1.2, increasing the diameter (ΔP) of the light beam (P) If it is difficult to be affected by the unevenness of the sensing object (3), the sensing object (to the sensing object) will move in a direction perpendicular to the light projection direction (arrow M) so as to cross the light beam (1)). Then, there was a problem that malfunctions occurred depending on whether or not the object to be detected (X) was completely irradiated with the K light beam (P) (parts P, ~P3 were irradiated). When the beam (P) is completely irradiated onto the detected object (N) as shown in Fig. 14, the center position of the condensed spot (S) on PSD (2flj) is X2, The center position x of the focused spot (S) is the positional information corresponding to the distance of the object (3)!
Output currents IA and IB based on 2 are output. In addition, Fig. 14 shows the case where the relay lens I (3c) is not used in order to simplify the removal of the armor, and the center position of the condensing spot (S) XI % X 2 , X
Distances are shown based on the gold standard. On the other hand, the object to be detected moves across the light beam (P), and as shown in FIGS. When the sensing object (3) is irradiated, that is, when the sensing object (X) enters or exits the light beam ψ), P
As the diameter of the focused spot (S) on S D (20) becomes smaller, its center position becomes X+ and X3, respectively.
becomes. In this case, PSD (2017) et al.
The fc output voltages k I A and IB are output, and the position detecting means (4) outputs the position code, l! :
Therefore, even though the detected object (N) does not exist within the detection area (DE), an object detection signal is output from the discrimination control means (5) and the output circuit (6) is activated. There was a problem.The second invention described below is intended to solve all of the above problems.

(Embodiment 3) Fig. 16 shows an embodiment of the second invention with a wedge-shaped prism (convex b), l! - A half mirror (convex d) is arranged between the half mirror (3cl) and a wedge shape that is arranged near the convergence point of the reflected light by the half mirror (3d) and bends the optical path. A second condensing means (2a) consisting of a prism (3b)' and a relay lens (3c)' is provided,
A light condensing spot (S) on the light surface of the second light condensing means (2a)
PSD (2
A second position detection means (4a) consisting of 0a) is provided, and a discrimination control means (5) similar to Embodiment 1 detects both positions IJ).
Means 14) (4a) Output fully synthesized signal (IA@-IA
') Based on (■B-+lB'), it is determined whether or not the detected object flash exists within a predetermined detection area, and the output circuit (61 is output).Here, both The position detection hand f&+41 (4a) generates reciprocal position signals (IA, IB) when a part of the light beam (P) (for example, P l , P a part) is reflected by the detected object (X), (I
A', IB') are output. However, the wedge-shaped ralism (3bH3b)' and the position detection means t
4) (4a) is a wedge-shaped prism (3b) (3b) with the same optical distance relationship as that of the half mirror (3d).
)' by setting the apex angle of the light beam C in the opposite direction KR.
When the - part of P) is reflected by the detected object (X),
Output current (IA, 1) of PSD (+!01 (20a)
B), (I6', IB') are made to be reciprocal. Nyobutsu S-smo sacrilege-←Nozu・Right-4=:b-+=+Be=U=-'4)-y4mei・1 苧also Goetsu Casting Inspector IP-
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Y discrimination control means f5+k The arrangement shown in FIG. 13 may be used.

(Created by IIJ of Example 3) Figure 17 is an η scrap diagram of the original lump of treasury +j 3, and below, based on Figure 17, the operation will be removed and J will be performed. Now, when the detected object (X) is completely irradiated with the light beam (P), P S D (20) (20a) Upper (7) S=S
? The eyebrows at the center of e spots (s) and (s)' are both X2, and the output currents (xA, IB) of both PSDe2o (20a)
), (IA', IB') are equal, and their combined positions (Il, -+f6') and (IB+11se') are naturally located at the position corresponding to X2, and the position to be detected is This is a slight contrast to the distance to object (X).

On the other hand, when only the PI portion of the light beam (P) is emitted onto the object to be detected (3), the center position B of the condensed spot (S) on the Fukiage becomes 11 xs, and P S
Focused spot on D (20a) (X at center position of S7)
Become I♂. Therefore, P S D(2o) (20a
) (7) Output (IA, l B ), CIA',
IA-+-IA'8 (IB') synthesized from
+1+U') - Focusing light - (S) (s'+ is Xl
If it is at the +X3 (-X2) position, the signal will be the same as the signal obtained when the light beam CP) is completely irradiated on the detected object ■, exactly corresponds to the distance t. Similarly, even if only part 23 of the light beam P) is irradiated onto the head of the detected object, the discrimination control means (5 ), and accurate position information is always input to the discrimination control means (5) regardless of whether or not the light beam P) is completely irradiated to the detected object (2).
Error 1iIJ when the tentatively detected object crosses the light beam (■
This means that I¥, can be prevented.

As described above, in the first invention, the second invention provides a method for inserting the lens between the condensing lens J (3a) of the first condensing means (2) and the wedge-shaped prism (3b) serving as the optical path bending means. a half mirror (convex d) serving as a light splitting means, and a wedge-shaped prism (3
b) A second light condensing means (2a) consisting of The second way
Position detecting means (4a) k are provided, and the detection control means (5) detects the detected object (X) in a predetermined detection area (DE) based on the output signal which is fully synthesized by the self-position detecting means f4) (4a). Check whether it exists within and output - path (6)? When a part of the light beam (P) is reflected by the detected object (3), the self-position detection means f4N, 4a) outputs a reciprocal signal. When the detected object (3) is partially irradiated with the light beam (P), the self-position detecting means (41 (4a); 6- outputs 14
Since the normal position signal is corrected and accurate position information is input to the discrimination control means (5), when the light beam (P) with a larger beam diameter crosses the gold-grade detection object (3) This has the advantage that malfunctions do not occur even if the Of course, it goes without saying that this invention has the same effects as the first invention.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a conventional example, Figs. 2 and 5 are diagrams showing the same operation theory F3)-3, Fig. 4 is a diagram showing the configuration of another conventional example, and Figs. 7 is a diagram showing the configuration of an embodiment of the present invention, FIG. 8 is a block circuit diagram of a main part of the same, FIG. 9 is a sectional view of the PSD used in the same, and FIG. 11 and 12 are operation explanatory diagrams of the same as above, FIG. 13 is a block circuit diagram of the main part of another embodiment, and FIG. 14 and 15 are diagrams showing problems of the same as above. , FIG. 16 is a diagram showing the complete structure of yet another embodiment, and FIG. 17 is an explanatory diagram of the same operation. Shins, (3bH3b)' Hakusahita Frism, (3d)
is a half mirror, (41 (4a) is a position detection means, (6
) is a discrimination control means, and (6) is an output circuit. Agent Patent Attorney Ishi 1) Long Figure 1↓'14' Figure 3

Claims (1)

[Claims] il+ Light projecting means for projecting a light beam onto the object to be detected, a condenser lens for condensing the reflected light of the light beam by the object to be detected, and a light beam reflecting from the object to be detected within the detection area. A light collecting path arranged near a light focusing point where the reflected light is focused by the focusing lens and bending the optical path, a light collecting means comprising a bending/bending means, and a light collecting means disposed on a light collecting surface of the light collecting means. and a position detection means that outputs compensation -Qf corresponding to the position of the condensed light spot, and controls an output circuit by determining whether or not the object to be detected exists within a predetermined detection area based on the output of the position detection means. A reflective photoelectric switch comprising a discrimination control means and a discrimination control means. (2) A light projecting means that projects a light beam onto the detected object, a condensing lens that collects the reflected light of the light beam from the detected object, and the reflection from the detected object within the detection area. a first condensing means comprising an optical path bending means disposed near a condensing point where light is condensed by the condensing lens and bending the optical path; a first light emitting means for outputting a position signal corresponding to the position of the focused light spot; a light splitting means inserted between the condensing lens of the first light focusing means and the optical path bending means; a second condensing means comprising an optical path bending means disposed near a convergence point of the reflected light by the light splitting means, and a condensing means disposed on a condensing surface of the second condensing means; A second position detection means outputs a position signal corresponding to the position of the light spot, and a second position detection means determines whether or not the detected object exists within a predetermined detection area based on a signal obtained by combining the output of the self-position detection means. A reflective type comprising a discrimination control means for controlling an output circuit, and a reciprocal signal is output from the dual-position i-toy detection handle when a part of the light beam is reflected by the object to be detected. Photoelectric switch.