JPH08330931A - Detection switch - Google Patents

Abstract

PURPOSE: To provide a detection switch which can set the proper threshold value by setting both threshold ON and OFF levels and also setting the center value between both threshold levels at a level lower than the arithmetical mean value of input levels. CONSTITUTION: The geometrical mean value is set at a level lower than the arithmetical mean value of both input levels V1 and V2 as the virtual center value. This geometrical mean value is equivalent to the equal level ratios set between 0 level and the center value Vceng. Then both threshold value Vthon and Vthoff are set with margins of the same width to the value Vceng. Thereby, the center value set between ON and OFF levels of the threshold value for detection of an object is set at a level lower than the arithmetical mean value of input levels set in two teaching modes. As a result, the substantially equal margins are secured among the signals of such types that have the input level variances which are frequently proportional to the absolute value of these input levels. Thus the input level variances can be stably detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic detection switches such as photoelectric switches, gloss switches, magnetic switches and ultrasonic switches.

[0002]

2. Description of the Related Art In a conventional electronic switch such as a photoelectric switch, light is applied to an object detection area to determine the presence or absence of an object, and the presence or absence of the object is determined based on the level of the reflected light. Then, in order to distinguish the object from the background or two objects, teaching is performed in advance, the level of the reflected light is judged while the object to be detected is arranged at a predetermined position, and the object is once held, and further distinguished from this. It is configured such that teaching is performed with the background and other objects arranged, the input level is held, and a threshold value is set to an intermediate value between them to determine the presence or absence of an actual object.

FIG. 9A shows two conventional input levels V.
1, V2 and their variation ranges are shown. Further, the detection level Vth _on and the non-detection level Vth _off set based on the input level and the stable detection level Vst _on and the stable non-detection level Vst _off set above and below the detection level Vth _on and the non-detection level Vth _off are shown. Is shown. In the conventional threshold setting method, there are two input levels V1 and V2.
The central value Vc of the arithmetic mean (V1 + V2) / 2 is set to the middle point of the above, and the detection level Vth _on and the non-detection level Vth _off are set by providing a hysteresis width with the same width above and below the value. The stable detection level Vst _on and the unstable detection level Vst _off are set within the same width.

[0004]

However, in such a conventional threshold value setting method for the detection switch, the optimum threshold value is not set. This causes two input level variations, but the level of the variation depends on the input level, and the higher the input level, the greater the variation. Here, the first and second input data V
The variation ranges of V1 and V2 are V1d and V in FIG. 9, respectively.
2d. Considering such variations, the upper limit value of such variations of the input level V1 and the non-detection level V
The difference between the level a1 of th _off and the difference a2 between the lower limit of the variation of the input level V2 and the detection level Vth _on was large. Further, the difference b1 between the upper limit of the variation of the input level V1 and the stable non-detection level Vst _off , and the difference b1 between the lower limit of the variation of the input level V2 and the stable detection level Vst _on b
The difference between 2 is also large. Therefore, there is a drawback that the setting of the threshold value is inappropriate for the variation of the input level. For this reason, there is a drawback that the substantial margins are not equal and the threshold level is not set appropriately.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a detection switch capable of setting an appropriate threshold value.

[0006]

According to the invention of claim 1 of the present application, a detecting means for detecting a level corresponding to a physical state,
Threshold setting means for inputting in advance the first and second input levels obtained from the detecting means for two physical states to be distinguished in the threshold setting mode, and setting the threshold based on the input level; In the detection switch, which comprises a discriminating means for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means, the threshold value setting means includes: A threshold on level and a threshold off level are set between the first input level and the second input level, and the central value of the threshold on level and the threshold off level is added to the first and second input levels. The feature is that the level is lower than the average value.

According to the invention of claim 2 of the present application, the detecting means for detecting the level corresponding to the physical state and the first and the second obtained from the detecting means for the two physical states to be distinguished in the threshold setting mode. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
A threshold on level and a threshold off level are set between the first input level and the second input level, and a central value of the threshold on level and the threshold off level is set to the first and second input levels. It is characterized in that it is a geometric mean value.

According to a third aspect of the present invention, the detecting means for detecting the level corresponding to the physical state, and the first and the second obtained from the detecting means for the two physical states to be distinguished in the threshold setting mode. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
A threshold on level and a threshold off level are set between the first input level and the second input level, and a central value of the threshold on level and the threshold off level is set to the first and second input levels. As a geometric mean value, the threshold on level and the center value, and the threshold value off level and the level difference up to the center value are distributed and set by the ratio of the input level.

According to a fourth aspect of the present invention, a detecting means for detecting a level corresponding to a physical state and two first and second physical states to be discriminated in the threshold setting mode are obtained from the detecting means. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
A threshold on level and a threshold off level are set between the first input level and the second input level, and a central value of the threshold on level and the threshold off level is set to the first and second input levels. The level is lower than the arithmetic mean value, and the difference between the threshold on level and either one of the first and second input levels close thereto and the difference between the threshold off level and the other input level are the ratios of the respective input levels. It is characterized in that the threshold on level and the threshold off level are set so as to be distributed by.

According to a fifth aspect of the present invention, a detecting means for detecting a level corresponding to a physical state and two first and second physical states to be distinguished in the threshold setting mode are obtained from the detecting means. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
The threshold on level and the threshold off level are set so that the level difference from the arithmetic mean value of the first and second input levels between the threshold on level and the threshold off level is distributed according to the inverse ratio of the input level. To do.

According to a sixth aspect of the present invention, the detecting means for detecting the level corresponding to the physical state and the first and the second obtained from the detecting means for the two physical states to be distinguished in the threshold setting mode. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
A threshold on level and a threshold off level are set between the first input level and the second input level, and a central value of the threshold on level and the threshold off level is set to the first and second input levels. It is characterized in that the level is lower than the arithmetic mean value, and the threshold on level and the threshold off level are set to a constant multiple of the first and second input levels and a reciprocal multiple of the constant, respectively. is there.

According to a seventh aspect of the present invention, a detecting means for detecting a level corresponding to a physical state and two first and second physical states to be identified in the threshold setting mode are obtained from the detecting means. By previously inputting the input level of, the threshold setting means for setting the threshold based on the input level, by comparing the threshold set by the threshold setting means in the detection mode and the input from the detecting means, In the detection switch, which comprises a discriminating means for discriminating two states, the threshold setting means,
The threshold on-level is set to a level lower by a certain percentage of one of the first and second input levels close thereto, and the threshold off-level is set to a level higher by the certain percentage of the other input level. It is a feature.

In the invention of claim 8 of the present application, the threshold on-level by the threshold setting means is a detection level for outputting a detection signal of an object, and the threshold off-level is a non-detection level for outputting non-detection of an object. A stable level detecting means for setting the stable detection level for the detection level and the stable non-detection level for the non-detection level to the same level difference is further provided.

According to a ninth aspect of the present invention, the threshold on-level by the threshold setting means is a detection level for outputting a detection signal of an object, and the threshold off-level is a non-detection level for outputting non-detection of the object. , A stable detection level and a stable non-detection level above and below the detection level and the non-detection level, respectively, which are distributed by the ratio of the higher input level of the first and second input levels to the other input level. Is further provided with a stable level setting means.

[0015]

According to the inventions of claims 1 to 9 having the above characteristics, the center of the threshold on level such as the detection level or the stable detection level and the threshold off level such as the non-detection level or the stable non-detection level. The value is set to a level lower than the arithmetic average value of the input level. The input from many detection means of the detection switch often has a large variation in the data corresponding to the absolute value of the input level, and when the threshold value is set based on the input signals from such various detection switches. By setting the threshold value corresponding to the input level, the margins of the threshold on level and the off level with respect to the variations of the first and second input levels can be made substantially equal to each other.

[0016]

1 is a block diagram showing the overall construction of an optical sensor device according to an embodiment of the present invention. In this figure, the optical sensor device 1 comprises a signal processing unit 2 and a head unit 3. The signal processing unit 2 has a light projecting circuit 5 that drives the light projecting element 4 at predetermined intervals, and an S-side light receiving circuit 8 and a P-side light receiving circuit 9 connected to the light receiving elements 6 and 7.
The light receiving circuits 8 and 9 are light receiving circuits for receiving the light of the S-polarized component and the light of the P-polarized component, respectively, and their outputs are given to the microcomputer (CPU) 10. An oscillator circuit 11, a power supply 12, a mode changeover switch 13, and a sensitivity setting button 14 are connected to the microcomputer 10, and an EEPROM 15 as a memory and an output circuit 16 are connected.
As will be described later, the microcomputer 10 periodically drives the light projecting element 5 at a predetermined timing based on these inputs, sets a threshold value by a light receiving signal, and detects a change in the surface state of the object. The output circuit 16 detects an object and outputs a detection output, and also detects a stable / unstable state of object detection and outputs a stable / unstable output.

Next, the structure of the head portion 3 will be described.
Three optical fibers 2 are provided between the signal processing unit 2 and the head unit 3.
1 to 23 are connected. The optical fiber 21 is an optical fiber for projecting light, one end of which is connected to the projecting element 4, and a lens 25 is arranged at an end portion on the head side thereof via a filter 24. The filter 24 is a polarization filter that outputs only the S-polarized component. On the light receiving side, the polarization beam splitter 26 is arranged at a position for receiving the reflected light of the emitted light. The polarization beam splitter 26 converts the received light into S
It is a beam splitter that separates a polarized light component and a P polarized light component. The S polarized light component is incident on the light receiving optical fiber 22 and the P polarized light component is incident on the light receiving optical fiber 23. The other ends of the optical fibers 22 and 23 for receiving light are respectively the light receiving elements 6 of the signal processing unit 2.
And 7 are connected.

The mode changeover switch 13 is a switch for changing over between the run mode and the teach mode. In the teach mode, every time the sensitivity setting button 14 is turned on, the output of the light receiving circuit obtained from the pair of light receiving elements is A / D-converted and taken into the microcomputer 10, and the coefficient of the evaluation function and the threshold value which will be described later are turned on by the value. This is a threshold setting mode for setting a level and a threshold off level. The run mode is a detection mode in which the detection level and non-detection level set in the teach mode are compared with the current signal level and an on / off signal is output.

Next, the operation of this embodiment will be described with reference to the flow chart. 2 and 3 are flowcharts showing the operation of this embodiment. When the operation is started, first, at step 31, it is checked whether the mode changeover switch 13 is in the teach mode. If it is the teach mode, the routine proceeds to step 32, where it is checked whether or not the sensitivity setting button 14 has been pressed, and it waits until it is pressed. In the teach mode, the sensitivity is set in two states to be distinguished. Here, the work 27 is arranged in front of the head portion 3 as shown in FIG. The work 27 has a blank white background area 27a which is not detected and a transparent tape area 27b attached thereon, and these objects are identified.

First, the white background area 27a of the work 27 is arranged so that the light from the light projecting element 4 can be irradiated, and the sensitivity setting button 14 is turned on. When the sensitivity setting button 14 is turned on, the process proceeds to step 33 to drive the light projecting element 4 via the light projecting circuit 5. Then, the light is emitted through the light projecting optical fiber 21, and only the light of the S-polarized component is emitted through the polarization filter 24 onto the white background area 27a of the work 27.
Then, the reflected light is converted into S by the polarization beam splitter 26.
The optical fiber 2 is separated into a polarized light component and a P polarized light component.
The light is received by the light receiving elements 6 and 7 of the signal processing unit 2 via 2 and 23. The received signals are converted into voltage signals by the S-side light receiving circuit 8 and the P-side light receiving circuit 9, respectively.
A / D conversion is performed in the microcomputer 10. The microcomputer 10 proceeds to step 34 to capture the S polarization component and the P polarization component as S _A and P _A , respectively.

Next, a predetermined work 2 in front of the head portion 3
The work 27 is moved so that the tape area 27b where the tape is attached to 7 is irradiated with light, and the process proceeds to step 35 to press the sensitivity setting button 14 again. Then, the light projecting circuit 5 is driven in the same manner, and S of the light from the light projecting element 4 is transmitted through the light projecting optical fiber 21 and the polarization filter 24.
Only the polarized component is incident on the region B of the work. The reflected light is separated by the polarization beam splitter 26, and the S-polarized component S _B and the P-polarized component P _B are taken into the microcomputer 10 via the A / D conversion circuit (step 37). Then, the process proceeds to step 38, and the glossiness X is discriminated by the difference between the outputs of the S-polarized component and the P-polarized component as described later. Further, the process proceeds to step 39, and the light amount Y is discriminated by the sum of the light amounts of the S-polarized component and the P-polarized component. Next, in step 40, the coefficients a and b that determine the evaluation function Z are determined using these values. Next, in steps 41 and 42, the detection level Vth _on and the non-detection level Vth _off are set, and then the stable detection level Vst _on and the stable non-detection level Vst are set.
Set _off . The detection level, the non-detection level, the stable detection level, the stable non-detection level and the coefficients a and b are written in the EEPROM 15 (step 43), and the processing in the teach mode is completed.

Next, the setting of the coefficients a and b and the detection levels and non-detection levels Vth _on and Vth _off will be described. FIG. 4 is a schematic diagram showing a reflection state of incident light with respect to an object having a low glossiness and an object having a high glossiness. In this figure, if the incident light is light having either one of the polarization components, for example, the S polarization component, specular reflection light in which the polarization direction is preserved can be obtained in an object having a low glossiness shown in FIG. 4A. In addition to that, the level of diffuse reflected light in which the S-polarized component and the P-polarized component are equal becomes high. On the other hand, if the glossiness is large, the total amount of diffuse reflected light in which the levels of the P-polarized component and the S-polarized component are equal as shown in FIG.
The level of the regular reflection light of the polarized light becomes relatively high. Therefore S
The glossiness can be detected from the difference between the polarized component and the P polarized component.

Here, as shown in FIG. 1, the work has a surface 27a having a low glossiness and a surface 27b having a high glossiness, which are to be discriminated from each other. For example, when the detection object (A) is irradiated with light and when the non-detection object (B) is irradiated with light so as to be in a physical state, a coefficient and a threshold value are set to identify them. The input value of the S-polarized component on the surface A of the work is S _A and the P-polarized component is P _A. The S-polarized component on the surface B of the work is S _B and the P-polarized component is P _B. At this time glossiness X _A, X _B reflected light Y _A, is defined as follows Y _{B. X A = S A -P A X} B = S B -P B Y A = S A + P A Y B = S B + P B then the surface of the workpiece A, the gloss difference X _S of B, the following equation the quantity difference Y _S Define in.

[Equation 1] In this way, X _S and Y _S take values of 0 to 100, respectively. Then, the evaluation function Z is determined by the following equation for the glossiness X and the light amount Y. Z = aX + bY Here, the coefficients a and b are determined by the following equations based on the gloss difference X _S and the light amount difference Y _S.

[Equation 2] The evaluation values Z obtained in this way are the evaluation values obtained when light is respectively incident on the surfaces A and B of the two workpieces as the first and second input levels V1 and V2. The detection level Vth _on and the non-detection level Vth _off are determined from these values.

FIG. 5A is a schematic diagram showing the setting of the threshold value in the first embodiment. A case where a threshold value is set by two input levels V1 and V2 obtained by teaching in this figure will be described. First, a level lower than the arithmetic mean of the two input levels V1 and V2, for example, a geometric mean value is set as a virtual center value. This is Figure 5
This is equivalent to making the ratio of the levels up to the central value Vceng as seen from the zero level shown in (a) equal. That is, V1: Vce
ng = Vceng: The central value Vceng for which V2 holds is set.
By doing this, Vceng is the geometric mean value of V1 and V2 √ (V1 ·
V2). Then, the threshold values Vth _on and Vth _off are set with a margin of the same width with respect to the center value Vceng. Here, V _H indicates a hysteresis width, which is obtained by equally dividing the hysteresis width. Therefore, the threshold values Vth _on and V
th _off is expressed by the following equation. Vth _on = Vceng + _VH / 2 Vth _off = Vceng- _VH / 2

Next, the setting of the threshold value according to the second embodiment will be described with reference to FIG. Virtual center value Vceng in the second embodiment is the geometric mean value as in the first embodiment, and its hysteresis width V _H. Then, this hysteresis width is distributed by proportional distribution. That is, Vceng to Vth
_{From on} to V _Ha , from Vceng to Vth _off to V _Hb ,
Vth _on and Vth _off are set by the following equations. V _H = V _Ha + V _Hb Vth _on = Vceng + V _Ha = Vceng + V _H × V2 / (V1
+ V2) Vth _off = Vceng + V _Hb = Vceng-V _H × V1 / (V1
+ V2). By doing this, the hysteresis width V _H can be set to the input level V
Since it can be distributed according to 1, V2, the threshold value can be set to a more appropriate value.

Next, a threshold value setting method according to the third embodiment of the present invention will be described. FIG. 5C is a diagram showing the setting of this threshold value. First, the first and second input levels V
The second input level V2 which is the higher level of V1 and V2
The width from Vth _on to Vth _on is a, and the width from the first input level V1 lower than V2 to Vth _off is b. Then, the respective intervals a and b from the input levels V2, V1 to the threshold values Vth _on , Vth _off are set by being distributed by proportional distribution of the input levels. That is, Vth _on and Vth _off are set by the following equations. Vth _on = V2-a = V2- _VA xV2 / (V1 + V
2) Vth _off = V1 + b = V1 + V _A × V1 / (V1 + V
2) Here, the sum of a and b is V _A. This V _A is V2-V1
The hysteresis width _VH is subtracted from this.

Next, setting of the threshold value according to the fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, 2
Hysteresis width for one input level V1 and V2 is V
_H, and the central value of arithmetic mean Vcena = (V1 + V2) / 2
And And c the width to the detection level Vth _on to this center value, when the width of up to Vth _off and d, c + d is the hysteresis width V _H. Then, Vth _on and Vth _off are set by inversely proportionally distributing the hysteresis width V _H to the central value Vcena obtained by the arithmetic mean. That is, Vth _on , V
th _off is defined by the following equation. Vth _on = Vcena + c = Vcena + V _H × V1 / (V1 +
V2) Vth _off = Vcena-d = Vcena- _VH * V2 / (V1 +
V2)

Next, the setting of the threshold value according to the fifth embodiment of the present invention will be described. FIG. 6B shows the setting of the threshold value according to the fifth embodiment. The threshold value is set so that the following equation V1: Vth _off = Vth _on : V2 is satisfied, that is, the values are similar to each other, using values from the zero level. That is, Vth _off / V1 = V2 / Vth _on = k. It goes without saying that at this time, Vth _on is made larger than Vth _off . Therefore, Vth _on and Vth _off are respectively expressed by the following equations. Vth _on = V2 / k Vth _off = V1 × k V2> Vth _on > Vth _off > V1 k> 1

Next, setting of the threshold value according to the sixth embodiment of the present invention will be described with reference to FIG. In this embodiment, the detection level Vth _on has V2 set to 1 and a value less than that by α, and the non-detection level Vth _off sets V1 to 1 and set α below this.
Use a large value. This α is a value in the range of 0 <α <1. For example, Vth _on and 95% of V2, Vth _off 105 of V1
%, Α becomes 0.05. When this is generalized, it is expressed by the following equation. Vth _on = V2 × (1-α) Vth _off = V1 × (1 + α)

Next, the setting of the stable detection level Vst _on and the stable non-detection level Vst _off in step 42 will be described. Vst _on and Vst _off are the hysteresis width V _H and distribution values a to d, as in the first to sixth embodiments described above.
It is possible to change k, α, etc. appropriately and set them in advance. In addition to this, the detection level Vth _on and the non-detection level Vth _off described in the methods 1 to 6 are set to 1 to 6
Substituting the input levels V1, V2 and V1 of the embodiment of
Based on this, Vst _on and Vst _off can be set from the methods 1 to 6. For example, as shown in FIG.
Th _on and Vth _off are set by the method of the first embodiment described above. That Vth _on this equal width as the geometric mean value Vceng as hysteresis width for the upper and lower sets Vth _off. Then, a stable detection level and a stable non-detection level whose sum is V _H ′ are set outside Vth _on and Vth _off by the following equation. _VH '= e + f Vst _on = Vth _on + e = Vth _on + _VH ' / 2 Vst _off = Vth _off -f = Vth _off -V _H '/ 2 In this way, the stable detection level and the stable non-detection level can be set. Becomes Needless to say, it can be set by the same method as in the second to sixth embodiments.

FIG. 9B shows the detection level Vth _on and the stable detection level Vst _on which are the threshold on levels set in this way.
FIG. 5 is a diagram showing a relation between a non-detection level Vth _off which is a threshold off level, a stable non-detection level Vst _off , and a variation between the two levels. As shown in this figure, the input level V1,
Assuming that V2 causes a variation according to its absolute value, unlike the conventional example, the level difference a1 between the upper limit of the variation of the input level V1 and the non-detection level Vth _off , and the lower limit of the variation of the input level V2 are detected. It is possible to make the difference a2 of the level Vth _on substantially match. Also, the difference b1 between the upper limit of the variation of the input level V1 and the level of the stable non-detection level Vst _off , and the lower limit b2 of the variation of the input level V2 and the level difference b2 of the stable detection level Vst _on can be made substantially the same level. It can be seen that an appropriate threshold value is set.

Next, in the flow chart shown in FIG.
If the mode changeover switch 13 is in the run mode at the time of judgment in step 31, the process proceeds to step 51 in FIG.
The detection level Vth _on , the non-detection level Vth _off, and the coefficient values a and b of the evaluation function Z are read from the OM. And step 5
Proceed to 2 to drive the light projecting circuit. Then the light emitting element 4
More light is emitted through the optical fiber 21, and the polarization filter 24 irradiates only the S-polarized component on the work.
The reflected light is separated into S-polarized light and P-polarized light and received by the light receiving element. The A / D converted value of this output is read into the microcomputer 10 (step 53). Then, in step 45, the evaluation function Z is calculated based on the following equation. Z = aX + bY Then, in step 55, the detection level Vth _on and the non-detection level Vth _off are compared with Z, and an on / off signal is output. Then, the process proceeds to step 56 and the mode changeover switch 1
It is checked whether or not 3 is the teach mode, and if not the teach mode, the process returns to step 52 and the same processing is repeated. In step 56, the mode changeover switch 13
2 is set to the teach mode, the process returns to step 32 of FIG. 2 and the same processing is repeated to set the coefficient values a and b, the detection level Vth _on , and the non-detection level Vth _off . In this way, two objects can be identified using the set threshold and evaluation function. Microcomputer 1
0 achieves the function of the threshold setting means for setting the threshold on level and the threshold off level as described later in steps 31 to 41 and 43, and in step 42 the stable / unstable detection level of detection is set. The function of the level setting means is achieved. Further, the light emitting element 4 and the light emitting circuit 5,
The head section 3, the light receiving elements 6 and 7, the light receiving circuits 8 and 9 and steps 52 to 54 of the microcomputer 10 constitute a detecting means for detecting the level corresponding to the physical state. Further, the microcomputer 10 performs steps 52 to 5
By comparing the input level and the threshold value in 5, the function of the discriminating means for discriminating the two physical states is achieved.

In the above-mentioned embodiment, the gloss detecting sensor for detecting the gloss is explained. However, the light projecting circuit irradiates the object detection area with light through the light projecting element to obtain a single light receiving element and a light receiving circuit. The level of the reflected light is detected by, and the first and second input levels V1,
It goes without saying that it can be applied to an ordinary photoelectric switch that obtains V2 and sets a threshold value during this period.

Next, a seventh embodiment of the present invention will be described. The detection switch according to the present embodiment is a high frequency oscillation type proximity switch, and a block diagram thereof is shown in FIG. In this embodiment, the oscillation circuit 61 is configured to include a resonance circuit 62, and the oscillation output is a frequency counter 63.
Is input to the signal processing circuit 64 via. The signal processing circuit 64 detects a metal object approaching the vicinity of the resonance circuit 62 based on the change of the oscillation frequency. As shown in FIG. 7B, the relationship between the oscillation frequency and the detection distance L to the detection object is such that the oscillation frequency sharply increases as the distance L becomes shorter. Therefore, the oscillation frequencies Fa and Fb are detected and held at the detection distances Lb and La, respectively, and the threshold value is set between them. If a variation ΔL in a certain range of the detection distance occurs, the frequency change ΔFa in the range La is larger than the frequency change ΔFb in the variation range Lb for the same variation distance. Therefore, if the threshold frequency is set by the method of each of the embodiments described above, it is possible to set the appropriate detection / non-detection level and stable / unstable detection level thresholds in accordance with the input variations. In FIG. 7A, a sensitivity setting circuit 65 is a circuit for setting two objects at distances La and Lb and performing teaching input. Based on these inputs, the frequency value of the frequency counter 63 is temporarily stored in the memory 66. Retained. Then, based on those frequency values, the above-mentioned first
The threshold on level and the threshold off level are set as in the sixth embodiment. In this way, it is possible to determine the presence / absence of an object having a variation with an appropriate threshold value.

An eighth embodiment in which the present invention is applied to an ultrasonic switch will be described with reference to FIG. In this embodiment, the ultrasonic transducer 7 is transmitted from the oscillation circuit 71 via the wave transmission circuit 72.
3 is driven, and ultrasonic waves are periodically sent in the direction of detecting an object. When the object approaches, the reflected wave of the ultrasonic wave is received at the level corresponding to the distance L to the detection distance, and the reflected wave is received via the ultrasonic transducer 74. Then, the signal is amplified through the receiving / amplifying circuit 75 and is determined as a detection signal through the integrating circuit 76. When the distance La to the detection object and the distance La is set at a position closer to the distance La, the sound wave level rapidly increases as the distance approaches, as shown in FIG. 7B. If the variation in the teaching position up to the object is ΔL, this ΔL
The variation of the volume level corresponding to the width of
ΔPa becomes large like Pa and ΔPb. Therefore, also in this case, the optimum threshold value can be set by setting the threshold on level and the threshold off level as in the above-described respective embodiments. In FIG. 8, the output of the integrating circuit 76 is input to the signal processing circuit 77. The signal processing circuit 77 holds these levels Pa and Pb in the memory 79 each time there is an input from the sensitivity setting circuit 68, and based on this, sets the threshold value as described above. When the teaching is completed, the detection mode is entered, and when the actual object is approaching, the threshold value is used for discrimination, and the object detection signal is output.

In this embodiment, the photoelectric switch, the gloss switch, the proximity switch, and the ultrasonic switch are described, but the present invention can be applied to various other detection switches.

[0037]

As described above in detail, according to the present invention, the central value of the on level and the off level of the threshold value for detecting an object is lower than the arithmetic mean value of the input levels at the time of teaching the two input levels. Since the level is set, the substantial margin is equal to various signals in which the variation of the input level is often proportional to the absolute value of the input level. Therefore, it is possible to stably detect a variation in the input level and to obtain a small difference in the input level.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an optical sensor device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation in a teaching mode of this embodiment.

FIG. 3 is a flowchart showing an operation in a run mode according to this embodiment.

FIG. 4 is a schematic diagram showing a relationship between specular reflection light and diffuse reflection light when light having a polarization direction is incident on an object having a low glossiness or an object having a high glossiness.

5A to 5C are diagrams showing a method of setting threshold values of a detection level and a non-detection level according to the first to third embodiments of the present invention.

6 (a) to 6 (c) are diagrams showing a method of setting threshold values for detection levels and non-detection levels according to fourth to sixth embodiments of the present invention, and FIG. 6 (d) is a diagram showing stable detection levels and stable non-detection levels. It is a figure which shows the setting method of a threshold value.

7A is a block diagram showing a configuration of a proximity switch according to a seventh embodiment of the present invention, and FIG. 7B is a graph showing a change in frequency with respect to a detection distance of the proximity switch.

FIG. 8A is a block diagram showing a configuration of an ultrasonic switch according to an eighth embodiment of the present invention, and FIG. 8B is a graph showing a change in volume level of ultrasonic waves with respect to a detection distance.

FIG. 9A is a relationship between a conventional input level and a threshold,
(B) is a diagram showing a relationship between an input level and a threshold value according to the first embodiment of the present application.

[Description of Reference Signs] 1 optical sensor device 2 signal processing unit 3 head unit 4 light emitting element 5 light emitting circuit 6,7 light receiving element 8 S side light receiving circuit 9 P side light receiving circuit 10 microcomputer 11 oscillation circuit 12 power supply circuit 13 Mode selector switch 14 Sensitivity setting switch 15 EEPROM 16 Output circuit 21-23 Optical fiber 24 Polarization filter 25 Lens 26 Polarization beam splitter 27 Work 61,71 Oscillation circuit 62 Resonance circuit 63 Frequency counter 64,77 Signal processing circuit 65 Sensitivity setting circuit 66 , 79 memory 67, 80 output circuit 72 wave transmitting circuit 73, 74 ultrasonic element 75 wave receiving amplifier circuit 76 integrating circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location H03K 17/94 9406-2G G01V 9/04 J (72) Inventor Shinji Mizuhata Ukyo, Kyoto City, Kyoto Prefecture 10 Hanazono, Doudou-cho, OMRON Corporation

Claims (9)

[Claims] 1. A detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for two physical states to be distinguished in a threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means sets a threshold on level and a threshold off level between the first input level and the second input level, and the threshold on level and the threshold A detection switch, wherein a central value of the off level is set to a level lower than an arithmetic mean value of the first and second input levels. 2. A detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for two physical states to be distinguished in the threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means sets a threshold on level and a threshold off level between the first input level and the second input level, and the threshold on level and the threshold A detection switch, wherein a central value of off-levels is a geometric mean value of the first and second input levels. 3. Detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for two physical states to be distinguished in the threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means sets a threshold on level and a threshold off level between the first input level and the second input level, and the threshold on level and the threshold The center value of the off level is the geometric mean value of the first and second input levels, and the threshold on level and the center value and the threshold off level and the level up to the center value Detection switch, characterized in that the set sorting by the ratio of the input level. 4. A detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for the two physical states to be distinguished in the threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means sets a threshold on level and a threshold off level between the first input level and the second input level, and the threshold on level and the threshold The central value of the off level is set to a level lower than the arithmetic average value of the first and second input levels, and the threshold on level and either the first or second input value close to the threshold on level are set. Detection switch, wherein the difference between the levels, that setting a threshold on level and threshold-off level as distributed by the difference of the respective ratio of the input level of the threshold-off level and the other input levels. 5. Detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for the two physical states to be distinguished in the threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means distributes the level difference from the arithmetic mean value of the first and second input levels of the threshold on level and the threshold off level according to the inverse ratio of the input level. A detection switch having a threshold on level and a threshold off level set as described above. 6. A detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for the two physical states to be identified in the threshold setting mode are input in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. The threshold value setting means sets a threshold on level and a threshold off level between the first input level and the second input level, and the threshold on level and the threshold The central value of the off level is set to a level lower than the arithmetic mean value of the first and second input levels, and the threshold on level and the threshold off level are respectively set to the first and the first off levels. Detection switch, characterized in that in which the set in the input level of the constant multiple and level number inverse number times the the constant. 7. A detection means for detecting a level corresponding to a physical state, and first and second input levels obtained from the detection means for the two physical states to be distinguished in the threshold setting mode are inputted in advance. A threshold value setting means for setting a threshold value based on the input level, and a discrimination method for discriminating the two states by comparing the threshold value set by the threshold value setting means with the input from the detecting means in the detection mode. In the detection switch including means, the threshold setting means sets the threshold on level to a level lower by a certain percentage of the first and second input levels close to the threshold on level, and sets the threshold off level to A detection switch, which is set to a level that is higher than the other input level by the predetermined percentage. 8. The threshold on level by the threshold setting means is a detection level for outputting a detection signal of an object, and the threshold off level is a non-detection level for outputting non-detection of an object, with respect to the detection level. 8. The stable level detecting means for setting the stable non-detection level and the stable non-detection level to the same level difference, respectively, further comprises stable level detecting means. Detection switch. 9. The threshold on level by the threshold setting means is a detection level for outputting an object detection signal, and the threshold off level is a non-detection level for outputting non-detection of the object. Stable level setting means for setting a stable detection level and a stable non-detection level distributed above and below the level, respectively, by the ratio of the higher input level of the first and second input levels to the other input level. The detection switch according to any one of claims 1 to 7, further comprising: