JPS63217716A - Photoelectric switch - Google Patents

Abstract

PURPOSE:To obtain an optical switch with low cost and high performance by providing a detection terminal comprising a light emitting element and a light receiving element blinked by a high frequency oscillation circuit and a referencing light emitting element whose blink period is opposite to that of the light emitting element and a referencing light receiving element, and applying addition/amplification/binarization to the signals of the signal light and the referencing light at the respective light receiving elements. CONSTITUTION:A reference light 13a of an element 12a becomes a light 13a inverting the period of the signal 13 by an inverter 11a with respect to the pulse light of the element 12. The signal light 13 radiates a body to be detected and its reflected light 15 is received by the element 16. The reference light 13a is received by the element 16a. The light is subject to photoelectric conversion, the signals 16c, 16b are added and inputted to a signal processing circuit 17. The summing signal 16d is subject to AC amplification 17a and only the fluctuation range of the signal is amplified, binaryzed (17b) by the threshold level and synchronized with the signal of the oscillation circuit by the circuit 17c, the circuit 17d confirms the pulse number to obtain an output in response to the presence of an object to be detected. Through the constitution above, the photoelectric switch detecting the fluctuation of a minute luminous quantity is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light-transmitting type optoelectronic switch or a light-reflecting type optoelectronic switch that detects the presence of an object, its position, rotation, etc. No slight photoelectric fluctuations
The present invention relates to an optoelectronic switch that also enables detection.

[Conventional technology]

Among the conventionally developed optoelectronic switch circuits, a reflection type circuit will be explained with reference to the drawings. As shown in the block diagram of FIG. 3, for example, 10 KHz,
Duty 1/10. It oscillates at a high frequency with a pulse width of 10 μBθC, and by pulse driving, the light emitted from the light emitting element (52) (for example, LFiD) (33) and the whole object to be inspected (34) Pi: irradiates,
Reflected light (35) reflected by the detected object (34)
i. The electric signal received by the light receiving element (36) and photoelectrically converted is processed by the signal processing circuit (37) to output an output according to the detected object. Here, the signal processing circuit (57) is a current amplification circuit (37) that amplifies the electric signal (36a) photoelectrically converted by the light receiving element (66).
a), a binarization circuit (37b) that binarizes the amplified electric signal (37θ) at a certain threshold level, a synchronization circuit (37c) that synchronizes with the oscillation circuit, and a binarization and synchronization It consists of a confirmation circuit (37d) which outputs the output signal (37f) by confirming the number of pulses.

FIG. 5 shows a timing chart of the block diagram shown in FIG. The operating principle of the reflective optoelectronic switch shown in FIG. 6 will be explained below with reference to FIG.

In Figure 6, 10 KHz, pulse width 10 μ
sec, a light emitting element (3
2] is (53) in Figure 5, and the amount of reflected light received by the light receiving element (66) is (55) in Figure 5. In the amount of reflected light (55), (A), ( A') represents the amount of light when there is no object to be detected, (0) is the amount of light when there is an object to be detected, and (B) and CB') represent the amount of light reflected by the object to be detected and enters the light receiving element. This is the amount of light generated during the transition period when the object to be detected disappears and the reflected light from the object to be detected stops entering the light receiving element 9. The amount of reflected light (55) is photoelectrically converted by the light receiving element (66) and sent to the AC amplification circuit (67) of the signal processing circuit (67) shown in FIG.
37a), the electric signal after through-width increase (5
7e) In (57e), f half (TholiLf) is the amount of reflected light (5
5) Transitional light amount (B).

(B')' represents the threshold level and the threshold level of the binarization circuit (37b) that removes and binarizes. If the current state of the output (weak) is "0#," ＃f”
ThoF#"2 setting (make the threshold level higher) Conversely, if the current state of the output (58) is "1", the threshold level /I/'th"' ThoPF
' (lower the threshold) and change the threshold as shown by the solid line.The amplified electrical signal (37θ) is converted to the binarization circuit (37b) in Figure 3.
If the level of each pulse is higher than the threshold, it becomes "1", and if it is smaller than the threshold, it becomes @0, and then becomes the electric signal (n f ) after binarization. l f ) is the synchronous circuit (S7
The output (58) is synchronized with c1 and synchronized and pulse-confirmed by the confirmation circuit (37cl). (The confirmation circuit (37d) shown in Fig. 3 confirms the level of one pulse in the binarized electrical signal (57f) shown in Fig. 5, and the level ef of the output (58) is obtained, but it is even more reliable. (To increase the sensitivity, it may be done with 3 to 5 consecutive pulse levels.) Kokotes threshold level - Tho
The difference between &J and Tho is the amount of hysteresis that ensures switch operation, and generally requires 30 to 40% of the amount of variation expressed by the following equation.

M=-X100 [Part] During Po sealing ceremony, K...Variation amount M...Variation rate PoW...Detection output when a detected object is present Po'P-F...・Detection output when there is no object to be detected Here, when the variation rate is small and the coefficient of variation is small, if the object to be detected is detected using a conventionally developed optoelectronic switch, the reflected light passes through the amplification circuit and As shown in Figure 6, the electrical signal after amplification (61
] The entire digital value circuit is binarized into “01” or “1”, but because the hysteresis is small, the transition period (B), C
The output from the confirmation circuit due to the binarized electrical signal (62) affected by B') is chattering as shown by diagonal lines as shown in (66). etc. may occur, resulting in unstable operation and reduced reliability.

Therefore, in order to maintain normal operation while increasing the hysteresis, the conventional technology uses clamp circuits (41aρ, (41a2) and amplification circuits (41b) as shown in FIG.
+ ), (411) Threshold for signal (71)? Output (731-
The method used was to accurately detect the difference in the detected object and perform a switch operation.

[Problem that the invention seeks to solve]

As shown in Fig. 4, an optoelectronic switch with multiple stages of clamp circuits and amplifier circuits requires the use of rectifying elements such as diodes in the clamp circuit, resulting in extremely high temperature dependence and the addition of multiple stages of amplifier circuits. This not only makes the circuit extremely complicated and increases the rate of malfunctions, but also increases the cost and size of the switch itself.

[Means for Solving the Problems] The present invention was obtained as a result of studies aimed at providing a photoelectronic switch that does not have the above-mentioned problems.
The main points are a high frequency oscillation circuit, a light emitting element for signals blinked by the oscillation circuit, an optical detection terminal such as a light receiving element that receives light from the light emitting element, and a signal detection terminal for signals blinked by the high frequency oscillation circuit. A reference light-emitting element with the blinking cycle of the light-emitting element reversed, a reference light-receiving element that receives light from the reference light-emitting element, an electrical signal from the signal light-receiving element, and an electric signal from the reference light-receiving element. A photoelectronic switch further comprises a signal processing circuit for amplification and binarization processing.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of an optoelectronic switch according to the present invention, and is an example of a reflective switch.

In Figure 1, (11) is a transmitting circuit, (12) is a signal light emitting element, (16) is a signal light receiving element, (11a) is an inverter, (12a) is a reference light emitting element, and (16a) is a The reference light receiving element (17) is a signal processing circuit, and the signal processing circuit (17) includes an amplification circuit (17a), a binarization circuit (171)), a synchronization circuit (17c), and a confirmation circuit ( 17d
).

Next, the operating principle of the reflective optoelectronic switch of the present invention having the above structure will be explained in detail with reference to FIGS. 1 and 2.

In FIG. 1, the amount of signal light (H) that is multiple-projected from the signal light emitting element (12) is determined by the oscillation circuit (11) with a frequency of 10ICH2 and a pulse width of 10 peec, as shown in (23) in FIG. , the reference light (?-!ia) emitted from the reference light emitting element (12a) is pulsed light with a period of 100 peec.
As a result, as shown in FIG. 2, a reference light amount (23a) is obtained which is inverted from the cycle of the signal light amount. When the signal light (16) is irradiated onto the object to be detected, the reflected light (15) is received by the multi-signal light-receiving element (16), and the amount of the received reflected light (15) is as shown in FIG. As shown in 25), when the amount of light from the detected object is small (At), when the amount of light from the detected object is large (C), and during the transition period (B).

(changes to 8. - 10,000, reference source (15) in Figure 1
A) is received by the reference light receiving element (16a).

After receiving the light, the reflected light (15) and the reference light (13a) are photoelectrically converted by the signal light receiving element (16) and the reference light receiving element (16a), resulting in a signal side electric signal (16c) and a reference side electric signal (
161)) and the electrical signal after addition (16(1)
and enters the signal processing circuit (17). FIG. 2 shows the alternating current waveforms of the signal multiplication +b signal (elbow c), the reference side electric signal (juice b), and the added electric signal (Wd).

In FIG. 1, the added electrical signal (16(1)) entering the signal processing circuit (17) is AC amplified by the AC amplification N path (17a) and becomes an amplified electrical signal (17θ).
Amplified electrical signal (27e) in which only the variation range (26a) of the electrical signal (26cL) shown in FIG. 2 is amplified
becomes. The electrical signal after amplification (24θ) is a binary electrical signal (1
7f), resulting in a continuous AC waveform shown in FIG. 2 (27f). Further, the binarized electric signal (17f) is synchronized with the oscillation signal of the oscillation circuit by the periodic circuit (17c), inputted to the confirmation circuit (17d), and the confirmation circuit (17d) confirms the Babas number. The output corresponds to the presence or absence of the object to be detected as shown in (2nd day) in FIG.

As described above in detail, in the optoelectronic switch of the present invention, the method of amplifying the added electrical signal (26d) obtained by adding the signal side electrical signal (26c) and the reference side electrical signal (26b) is used. "Tho bowl" of Denshin Azusa (27e) after increasing the width, @"Tho31!-f
It is possible to make a large difference in hysteresis (hysteresis ← lysis), and even if the variation rate M is extremely small, it can be detected, resulting in an extremely sensitive optoelectronic switch. In addition, according to the present invention, the level setting of the switch sensitivity, etc., only needs to be done by fully adjusting the peak output of the reference light amount (la), and the adjustment method can also be used when the amount of light from the object to be detected is small, or when the amount of light from the object to be detected is small. The setting may be made with reference to the output when there is a large amount of light f. Note that the optoelectronic switch of the present invention can be used as either a transmission type optoelectronic switch or a reflective type optoelectronic switch.

Another embodiment is shown in FIG. Figure 8 shows the signal light emitting element (
12) and the tip of the signal light-receiving element (16), and between the reference light-emitting element (12a) and the reference light-receiving element (16a), there are light guides (81), (82), (83) such as optical fibers.
), it is possible to create a photoelectronic switch with good operability and high sensitivity. Further, by emitting light and irradiating the signal light emitting element (16), the above-mentioned signal electric signal and reference electric signal are added in a state of golden light, and the same effect is obtained.

〔Effect of the invention〕

According to the present invention, compared to the conventional example shown in Fig. 4, the number of parts is much smaller and the temperature characteristics are improved, so the causes of failure are reduced, and the switch can be easily replaced with an ordinary optoelectronic switch at low cost. We have been able to provide an optoelectronic switch that can detect minute fluctuations in light intensity and has numerous advantages such as being easily modified and easy to install.

Further, the photoelectronic switch of the present invention can be applied to color processors, arc sensors, flaw detection sensors, etc. by utilizing the switch function metal of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the reflective optoelectronic switch of the present invention, FIG. 2 is a time chart showing the operation of FIG. 1, and FIG. 3 is a block diagram showing a conventional reflective optoelectronic switch. Figure 4 is a block diagram of a conventional reflective optoelectronic switch that can detect even a few fluctuation rates M, Figures 5 and 6 are time charts showing the operation of Figure 6, and Figure 7 is the operation of Figure 4. 8 and 9 are block diagrams showing other embodiments of the reflective optoelectronic switch of the present invention. In addition, in the symbols used in the drawings, 11.31...Oscillation circuit 12...Signal light emitting element 12a...Reference light emitting element 16...Signal light receiving element 16a ...Reference light receiving element 17.37...Signal processing circuit 14...Detected object collection 7I! 1. 2nd punishment, 3. Concave 4, 5 foxes, 2. concave dragons, 7.

Claims (4)

[Claims] (1) A high-frequency oscillation circuit, an optical detection end consisting of a signal light-emitting element blinked by the oscillation circuit and a signal light-receiving element that receives light from the light-emitting element, and a signal light-emitting element blinked by the high-frequency oscillation circuit. After adding the electrical signals from the reference light-emitting element with the blinking period reversed, the reference light-receiving element that receives the light from the reference light-emitting element, the signal light-receiving element, and the reference light-receiving element, An optoelectronic switch comprising a signal processing circuit for width binarization processing. (2) A photoelectronic switch according to claim 1, characterized in that a light guide is coupled to a signal light emitting element and a signal light receiving element as an optical detection end. (3) A photoelectronic switch according to claim 1, characterized in that a light guide for transmitting and receiving light is coupled between a reference light emitting element and a reference light receiving element. (4) The optoelectronic switch according to claim 1, wherein a signal light receiving element is used as the reference light receiving element.