JP3359380B2 - Photoelectric switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and lightweight photoelectric switch having a function of evaluating the presence / absence of articles.

[0002]

2. Description of the Related Art A photoelectric switch used for detecting the presence or absence of an article at a remote place includes a light emitting circuit for causing a light emitting element to emit light,
A small and light-weight one in which circuit elements such as a light-receiving circuit for processing a light-receiving signal of a light-receiving element that receives light from the light-emitting element and a power supply circuit of the light-emitting circuit and the light-receiving circuit are incorporated in one package has been awarded. Some of these photoelectric switches have a light receiving circuit that has the function of evaluating the presence / absence detection accuracy of an article by itself.
FIG. 2A shows an example of a circuit for evaluating the presence / absence detection accuracy of an article of a photoelectric switch, which will be described.

FIG. 2A shows an article presence / absence detection accuracy level evaluation circuit (23) and an article presence / absence detection accuracy level display circuit (25). The level evaluation circuit (23) is incorporated in a one-chip integrated circuit component (24). The level evaluation circuit (23) compares the voltage level of the light receiving signal A from the light receiving element (1) with the upper stable level H1, the lower stable level L and the margin level H2 shown in FIG. Signal B
And a margin signal C are output. Further, the voltage level of the light receiving signal A is compared with a reference level F for detecting the presence or absence of an article, and a control signal indicating the presence or absence of an article is output from the comparison result. The circuit for outputting such a control signal is shown in FIG. ).

The upper stable level H1 is a constant voltage level higher than the reference level F. When the voltage level of the light receiving signal A is higher than the upper stable level H1, it is determined that the photoelectric switch is in a stable operation state, and the stability signal is determined. B is output.
The lower stable level L is a constant voltage level smaller than the reference level F. When the voltage level of the light receiving signal A is lower than the lower stable level L, it is determined that the photoelectric switch is in a stable operation state, and the stability signal B is output. Is output. Margin level H2
Is a constant voltage level higher than the upper stable level H1, and when the voltage level of the light receiving signal A becomes equal to or higher than the margin level H2, it is determined that the photoelectric switch is in a more stable operation state, and the margin signal C is output.

As shown in FIG. 2A, a light receiving signal A output from a light receiving element (1) after receiving light from a light emitting element (not shown) is amplified by an amplifier circuit (2). The signals are sent to the first to third comparison circuits (12) to (14). The first comparison circuit (12) outputs the stability signal B to the OR circuit (15) when the voltage level of the amplified light receiving signal A is lower than the lower stable level L. The second comparison circuit (13) outputs the stability signal B to the OR circuit (15) when the voltage level of the amplified light receiving signal A is equal to or higher than the upper stable level H1. O
The stability signal B input to the R circuit (15) is output to the first output terminal (21) as it is. Third comparison circuit (1
4) outputs the margin signal C to the second output terminal (2) when the voltage level of the amplified light receiving signal A is equal to or higher than the margin level H2.
Output to 2).

A level display circuit (25) is connected to the first and second output terminals (21) and (22). Level display circuit (25)
Is composed of a stable operation display means (26) connected to the first output terminal (21) and a margin display means (27) connected to the second output terminal (22). Stable operation display means (26)
Is a series circuit of, for example, a light emitting diode (28) and a field effect transistor (hereinafter referred to as FET) (29).
When the stability signal B is output to the output terminal (21) of the light emitting diode (2), the output voltage turns on the FET (29) to turn on the light emitting diode (2).
8) lights up and stable operation display is performed. The margin display means (27) is also a series circuit of the light emitting diode (30) and the FET (31). When the margin signal C is output to the second output terminal (22), the output voltage indicates the FET (31). Is turned on, the light emitting diode (30) is turned on, and the margin is displayed.

[0007]

The above-mentioned integrated circuit component (24) is packaged together with other integrated circuit components such as a power supply circuit in a resin mold package, so that the photoelectric switch can be reduced in size and weight. ing. However, FIG.
The integrated circuit component (24) having the level evaluation circuit (23) of (a) is connected to a first output terminal (2
1) and a second output terminal (22) for outputting the margin signal C
In this case, it is difficult to reduce the size of the photoelectric switch packaged in a resin mold from the wiring space.

Therefore, the object of the present invention is to
It is an object of the present invention to provide a photoelectric switch in which the number of output terminals of an integrated circuit component in which a level evaluation circuit is incorporated is reduced and the size and weight are easily reduced.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a photoelectric switch when a voltage level of a light receiving signal from a light receiving element is equal to or higher than an upper stable level exceeding a predetermined reference level or equal to or lower than a lower stable level lower than the reference level. A stability detection circuit that outputs a constant-voltage stability signal by determining that the photoelectric switch is in a stable operation state; and a photoelectric switch further comprising: A margin detection circuit that outputs a constant voltage margin signal that exceeds the constant voltage of the stability signal by determining that the operation is in a stable operation state, and an addition that adds each output signal of the stability detection circuit and the margin detection circuit. The object is achieved by forming an adder circuit that outputs a signal to an output terminal into an integrated circuit.

Further, according to the present invention, the voltage level of the added signal output to the output terminal of the integrated circuit component having the stability detection circuit, the margin detection circuit, and the addition circuit is detected by the stability detection circuit. The stable operation display means that operates when the voltage corresponding to the constant voltage level of the circuit stability signal is displayed to indicate that the photoelectric switch is in a stable operation state, and the voltage level of the addition signal output to the output terminal is A margin display means that operates when the voltage level corresponds to the voltage level obtained by adding the margin signal of the margin detection circuit to the stability signal of the stability detection circuit, and indicates that the photoelectric switch is in a more stable operation state. Are connected.

[0011]

When a margin signal is output from the margin detection circuit, a stability signal is always output from the stability detection circuit.
When the margin signal is not output from the margin detection circuit,
The stability detection circuit may or may not output a stability signal. Therefore, the signal obtained by adding the output signals of the stability detection circuit and the margin detection circuit by the addition circuit includes the stability signal and the margin signal. The three signals of the high voltage level signal to which the stability signal is added, the medium voltage level signal only for the stability signal, and the low voltage level signal without the stability signal are included, and the level evaluation of the stability and the margin from the added signal is performed. It is possible to reduce the number of terminals, reduce the number of terminals, and reduce the size of the photoelectric switch. Weight reduction becomes easy.

Further, the stable operation display means and the margin display means are connected to the output terminal of the adding circuit, and the stable operation display means is operated when the photoelectric switch is in a stable operation state, so that the photoelectric switch is further stabilized. If the margin display means is operated in the operating state, it is possible to clearly see the good or bad of the operating state of the photoelectric switch, and work such as optical axis alignment of the photoelectric switch becomes easy.

[0013]

An embodiment will be described with reference to FIGS. 1 (a) and 1 (b). Note that the same or corresponding parts as those of the photoelectric switch of FIG. 1A are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1A shows an article presence / absence detection accuracy level evaluation circuit (8) and an article presence / absence detection accuracy level display circuit (9). The level evaluation circuit (8) is a one-chip integrated circuit component. Incorporated in (7). The difference between the level evaluation circuit (8) and the level evaluation circuit (23) of FIG.
OR circuit (15) from first and second comparison circuits (12) and (13)
The stability signal B output from the third comparator and the margin signal C output from the third comparison circuit (14) are added by an adding circuit (5), and the added signal D is output to one output terminal (6). That is to say. A stability signal B from a stability detection circuit (3) including a first comparison circuit (12), a second comparison circuit (13), and an OR circuit (15), and a third comparison circuit (14) The margin signal C from the margin detection circuit (4) composed of a constant voltage V is output by, for example, an attenuator (15) (16).
The voltage is made constant to 0 and output to the addition circuit (5). A level display circuit (9) is connected to one output terminal (6) as needed.

When the stability detection circuit (3) compares the voltage level of the light receiving signal A with the upper stability level H1 or the lower stability level L and outputs the stability signal B, the addition circuit (5) outputs the voltage level V0 to the addition circuit (5). A constant voltage signal is input. When the margin detection circuit (4) compares the voltage level of the light receiving signal A with the margin level H2 and outputs the margin signal C, the constant voltage signal of the voltage level V0 is input to the addition circuit (5). . The addition signal D output from the addition circuit (5) to the output terminal (6) by adding the two input signals of the constant voltage V0 is four kinds of signals S1 to S4 as shown in FIG.

FIG. 1B is a voltage waveform diagram in which the vertical axis indicates the voltage level of the addition signal D and the horizontal axis indicates the voltage level of the light receiving signal A. The voltage level of the light receiving signal A is the lower stable level L
In the following cases, the addition signal D becomes the signal S1 of the voltage level V0 based on the stability signal B. When the voltage level of the light receiving signal A is between the lower stable level L and the upper stable level H1,
Since the stability signal B and the margin signal C are not output to the addition circuit (5), the addition signal D is a signal S2 having a zero voltage level. When the voltage level of the light receiving signal A is equal to or higher than the upper stable level H1, the addition signal D becomes the signal S3 of the voltage level V0 based on the stability signal B. Further, when the voltage level of the light receiving signal A is equal to or higher than the margin level H2, the addition signal D corresponds to the sum of the stability signal B and the margin signal C, and becomes the signal S4 of the voltage level 2V0.

Therefore, if the addition signal D is read at the voltage level, it can be determined whether the stability signal B and the margin signal C are output to the output terminal (6). For example, the addition signal D is divided into a constant comparison level Vt1 smaller than the constant voltage V0 and a constant comparison level Vt larger than the constant voltage V0 and smaller than 2V0.
When comparing at t2, when the voltage level of the addition signal D is lower than the comparison level Vt1, the stability signal B and the margin signal C are not output, and the voltage level of the addition signal D is between the comparison level Vt1 and the comparison level Vt2. In some cases, only the stability signal B is output, and when the voltage level of the addition signal D is equal to or higher than the comparison level Vt2, it can be determined that the stability signal B and the margin signal C have been output.

As described above, the output terminal (6) of the integrated circuit component (7) of the level evaluation circuit (9) is changed from the conventional two-output terminal to one, and the integrated circuit is reduced by the number of terminals. The component (7) is reduced in size, and the photoelectric switch is reduced in size and weight.

The level display circuit (9) connected to one output terminal (6) of the integrated circuit component (7) includes a stable operation display means (1).
0) and a margin display means (11). The stable operation display means (10) includes, for example, a light emitting diode (17) and
ET (18) is a series circuit, and the margin display means (11) is also a series circuit of the light emitting diode (19) and the second FET (20), and the gates of the first and second FETs (18) and (20) are output. Connected to terminal (6). First and second FETs (18) (20)
The first FET (18) conducts when the voltage level applied to the gate is equal to or higher than the comparison level Vt1 to cause the light emitting diode (17) to emit light, and the second FET (20) Conducts when the voltage level applied to the gate is equal to or higher than the comparison level Vt2, causing the light emitting diode (19) to emit light.

That is, when the stability signal B is output from the stability detection circuit (3) of the integrated circuit component (7) and the constant voltage V0 is applied to the output terminal (6), the constant voltage V0 One FET (18) is turned on, and the light emitting diode (17) for stable operation display is turned on. At this time, since the constant voltage V0 of the output terminal (6) is smaller than the comparison level Vt2, the second FE
T (20) does not conduct and the light emitting diode (1
9) does not light. A margin signal C is output from the margin detection circuit (4) of the integrated circuit component (7), and a constant voltage 2V0 obtained by adding the voltage of the margin signal C and the stability signal B is applied to the output terminal (6). Then, at this constant voltage 2V0, the first F
Both the ET (18) and the second FET (20) conduct, and the light emitting diode (17) for displaying a stable operation and the light emitting diode (19) for displaying a margin are turned on.

[0021]

According to the present invention, the outputs of the stability detection circuit and the margin detection circuit are added by the addition circuit, and the addition signal output to one output terminal is read at the voltage level, whereby 1
Since a stability signal and a margin signal can be obtained from the output terminal,
The number of output terminals of the integrated circuit component for evaluating the level of the article presence / absence detection accuracy can be reduced to only the output terminal of the addition signal, and the reduction in the number of terminals facilitates the reduction in size and weight of the photoelectric switch.

Also, by connecting the stable operation display means and the margin display means to the output terminal of the adder circuit to display the stable operation display and the margin display of the photoelectric switch, the operational state of the photoelectric switch can be determined at a glance. The operation such as alignment of the optical axis of the photoelectric switch becomes easy.

[Brief description of the drawings]

FIG. 1A is a block diagram of a main part of a photoelectric switch circuit showing one embodiment of the present invention, and FIG. 1B is a block diagram of FIG.
It is a voltage waveform diagram of a light receiving signal and an addition signal in a photoelectric switch.

FIG. 2A is a block diagram of a main part of a switch circuit of a conventional photoelectric switch, and FIG. 2B is a voltage for explaining voltage level evaluation of a light receiving signal in the photoelectric switch of FIG. 2A; It is a level diagram.

[Explanation of symbols]

 1 Photodetector 3 Stability detection circuit 4 Margin detection circuit 5 Addition circuit 6 Output terminal 7 Integrated circuit component 10 Stable operation display means 11 Margin display means A Light reception signal B Stability signal C Margin signal D Addition signal L Lower stable Level H1 Upper stable level H2 Extra level

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Setsuo Makino 2-1-1-12 Sonezaki, Kita-ku, Osaka-shi, Osaka Hokuyo Electric Co., Ltd. (56) References JP-A-1-320818 (JP, A) JP-A 57-6738 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H03K 17/78

Claims (2)

(57) [Claims] 1. A voltage level of a light receiving signal from a light receiving element is equal to or higher than an upper stable level exceeding a predetermined reference level, or
A stability detection circuit that determines that the photoelectric switch is in a stable operation state and outputs a constant voltage stability signal when the lower level is equal to or lower than the lower stable level lower than the reference level; A margin detection circuit that determines that the photoelectric switch is in a more stable operation state and outputs a margin signal of a constant voltage exceeding the constant voltage of the stability signal when the margin is equal to or higher than a predetermined margin level exceeding the stability level; and ,
An optoelectronic switch comprising: an integrated circuit component including an adder circuit for outputting, to an output terminal, an added signal obtained by adding each output signal of the stability detection circuit and the margin detection circuit. 2. The circuit according to claim 1, wherein the voltage level of the added signal output to the output terminal corresponds to the constant voltage level of the stability signal of the stability detection circuit. And the stable operation display means for displaying that the photoelectric switch is in a stable operation state, and the voltage level of the addition signal output to the output terminal is detected by the stability signal of the stability detection circuit. A photoelectric switch comprising: a margin display unit that operates when the voltage level corresponds to a voltage level obtained by adding a circuit margin signal, and indicates that the photoelectric switch is in a more stable operation state.