JPH11225058A - Photoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust an optical axis by displaying a light receiving level and a peak value in the case of adjusting the optical axis in the photoelectric sensor. SOLUTION: A light receiving level is displayed by using a light receiving level display section 8a provided for the photoelectric sensor in the adjustment of an optical axis. Furthermore, a threshold value display section 8b provided for the photoelectric sensor is used to display a peak light receiving level in the case of adjusting the optical axis. Moreover, when the light receiving level is within a prescribed range from the peak level, an output display element 8c displays it that the level is within the peak range. Thus, the end of the optical axis adjustment is easily recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a photoelectric sensor.
In particular, the present invention relates to a photoelectric sensor having a feature in display at the time of optical axis adjustment.

[0002]

2. Description of the Related Art In a transmission type photoelectric sensor, it is necessary to adjust an optical axis so that an optical axis of a light emitting part and an optical axis of a light receiving part are coincident when the optical sensor is installed. Even in the case of a reflection type photoelectric sensor, it may be necessary to adjust the optical axis in order to set the light irradiation position on the work to a predetermined position.

In order to easily adjust the optical axis in a conventional optical fiber type photoelectric sensor, the optical axis is changed by changing the number of light emitting pulses of the light emitting element based on the amount of light received by the light receiving optical fiber. There has been proposed a photoelectric sensor in which the intensity of a light beam emitted from the end face of an optical fiber becomes stronger as they match, and a photoelectric sensor in which the period of light and darkness changes as the optical axis matches (Japanese Patent Application Laid-Open No. HEI 9-163572). No. 2-203617). Also, when the optical axis is adjusted, the peak value is held, and when the peak value is updated, a threshold value is set up to a predetermined level equal to or less than the peak value. There has also been proposed a photoelectric sensor capable of recognizing brightness and facilitating optical axis adjustment (JP-A-6-318855).

[0004]

However, in such conventional optical axis adjustment methods, it is necessary to adjust the optical axis by looking at the projection axis of the optical fiber type photoelectric sensor. There is no display on the connected sensor body. Also, since the degree of coincidence of the optical axes cannot be sufficiently recognized, there is a disadvantage that the optical axis adjustment is difficult and the adjustment takes time.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to easily recognize the degree of coincidence of the optical axis on the photoelectric sensor body side. And Another object of the present invention is to enable the completion of optical axis adjustment to be displayed on the photoelectric sensor main body side.

[0006]

According to a first aspect of the present invention, there is provided a light projecting unit having a light projecting element for projecting light, and receiving light emitted from the projecting unit via a detection area. Light-receiving part,
A signal processing means for discriminating a characteristic amount determined based on a light receiving level with a predetermined threshold value, a first group of level display elements for displaying the level of the characteristic amount, and a threshold value corresponding to the first group of level display elements. In a photoelectric sensor having a second group of level display elements for displaying a level, the photoelectric sensor has a level display means for displaying a level received by the light receiving unit at the time of optical axis adjustment by the first group of level display elements. Is what you do.

According to a second aspect of the present invention, there is provided a light projecting section having a light projecting element for projecting light, a light receiving section for receiving light emitted from the light projecting section via a detection area, and a light receiving section. A signal processing means for discriminating a feature value determined based on the level with a predetermined threshold value, a first group of display elements for displaying the level of the feature value, and a set threshold value corresponding to the first group of display elements. In a photoelectric sensor having a second display element group for displaying a level, a peak value holding unit for holding a peak value of a level received by the light receiving unit at the time of optical axis adjustment, and a peak value held by the peak value holding unit And a peak value display unit for displaying the level of the second group on the level display elements of the second group.

According to a third aspect of the present invention, there is provided a light projecting section having a light projecting element, for projecting light, a light receiving section for receiving light emitted from the light projecting section via a detection area, and a light receiving section. A signal processing means for discriminating a feature value determined based on the level with a predetermined threshold value, wherein the photoelectric sensor has a level display means for displaying a level received by the light receiving unit by an level display element at the time of optical axis adjustment. It is characterized by the following.

According to a fourth aspect of the present invention, there is provided a light projecting section having a light projecting element for projecting light, a light receiving section for receiving light emitted from the light projecting section via a detection area, and a light receiving section. A signal processing unit that discriminates a feature amount determined based on a level with a predetermined threshold value, a peak value holding unit that holds a peak value of a level received by the light receiving unit during optical axis adjustment, And a peak value display means for displaying the level of the peak value held by the peak value holding means on a level display element.

According to a fifth aspect of the present invention, there is provided a light projecting section having a light projecting element for projecting light, a light receiving section for receiving light emitted from the light projecting section via a detection area, and a light receiving section. A signal processing unit that discriminates a characteristic amount determined based on a level with a predetermined threshold value, a peak value holding unit that holds a peak value of a level received by the light receiving unit during optical axis adjustment, Peak range display means for displaying a peak range when a light receiving level within a certain range including the peak value held by the peak value holding means is obtained at the time of optical axis adjustment using a display means for displaying an operation state at a time. When,
It is characterized by having.

[0011]

FIG. 1 is a block diagram showing an overall configuration of a photoelectric sensor according to an embodiment of the present invention. In this figure, a light projecting circuit 2 receives a light projecting pulse from a microcomputer 1 and drives a light projecting element 3 according to the light projecting pulse. Part of the light emitted from the light projecting element 3 to the object detection area becomes light of a different level depending on the presence or absence of an object, its surface state, and the like, and enters the light receiving element 4 such as a photodiode. The light receiving circuit 5 converts a light receiving amount into a light receiving signal, and an output thereof is given to the microcomputer 1 via the amplifier unit 6. The light emission processing unit 1a in the microcomputer 1 generates a light emission pulse at a fixed timing when detecting an ordinary object, as described later, and emits a larger amount of light when adjusting the optical axis and checking the light emission spot. A light pulse is generated and output to the light projecting circuit 2. The A / D converter 1b is connected to the amplifier 6
A / D-converts the received light signal given by the
c or to the teaching processing unit 1d.
The determination processing unit 1c performs A / D operation in the operation mode (RUN mode).
Signal processing means for determining an external physical state, that is, the presence or absence of an object, from a predetermined threshold value based on the converted value, and outputs the determination output to the output unit 7 via the output processing unit 1e. The output of the determination processing unit 1c is also provided to the display processing unit 1f. The display processing unit 1f displays a light input level, a threshold value, and the presence or absence of object detection in an operation mode, and performs processing for displaying a light input level, a peak value, and a peak range in a sensitivity setting mode. Output to the display unit 8.
The teaching processing unit 1d determines a threshold based on the operation of the teaching switch in the sensitivity setting mode, and the light receiving state in the sensitivity setting mode is determined by the display processing unit 1d.
It is configured to be displayed on the display unit 8 via f. The input unit 9 switches an operation mode and an output mode and inputs a teaching signal.

Here, the light projecting element 3 and the light receiving element 4 may be configured to project or receive light directly to an object detection area via an optical system, and may constitute a reflection type or transmission type photoelectric sensor. Alternatively, the light from the light projecting element 3 may be guided to the object detection area via an optical fiber (not shown), and a light receiving optical fiber may be arranged to face the object detection area to form an optical fiber transmission type photoelectric sensor. Further, the optical fiber for projecting and receiving light may be directed to the object detection area to form an optical fiber type reflection type photoelectric sensor.

FIG. 2 is a diagram showing a panel surface of the photoelectric sensor. On the panel surface of the photoelectric sensor according to this embodiment, a level display section 8a composed of a light emitting diode (LED), which is a first group of level display elements for displaying a light receiving level, is provided as a display section 8. In order to display a threshold value set at an intermediate portion of each level, an LED of a threshold value display section 8b, which is a second group of level display elements, is provided. Further, an output display element 8c that is turned on when the output is turned on in the object detection state is provided above the output display element 8c. In this embodiment, the display element of the first group is a display section of the light receiving level when the optical axis is adjusted, the display element of the second group is the display section of the peak value when the optical axis is adjusted, and the output display element 8c is the peak range when the optical axis is adjusted. Is used as a peak range indicator light.

On the other hand, the input section 9 is provided with a mode switch 9a for switching between an operation mode (RUN mode) and a sensitivity setting mode (TEACH mode). In the present embodiment, it is assumed that the position of the projected light spot of the photoelectric sensor and the optical axis adjustment are performed in the sensitivity setting mode, and the sensitivity setting mode is also the optical axis adjustment mode. The input section 9 is provided with a push button type teaching switch 9b for giving a signal at a specific timing of teaching, and an output mode changeover switch 9c for switching the output mode between light-on and dark-on.

FIG. 3 is a diagram for explaining the function of the display processing section 1f in the microcomputer 1 in more detail. As shown in the figure, the display processing unit 1f has functions of a level display unit 1g for displaying a level at the time of optical axis adjustment, a peak value display unit 1h for displaying a peak value, and a peak range display unit 1i for displaying a peak range. The respective level display outputs are output to the above-described level display section 8a, threshold value display section 8b, and output display element 8c. The display processing section 1f is provided with a peak value holding means 1j for holding a peak value.

Next, the operation of this embodiment will be described with reference to a time chart and a flowchart. FIG.
5 is a flowchart showing processing of the microcomputer 1 in the operation mode. When the operation is started, first, in step S1, it is checked whether or not the operation mode is the operation mode (RUN mode). If the mode changeover switch 9a is on the "RUN" side, the process proceeds to step S2 to perform light emission processing, and
Light emission pulses are generated at a constant period as shown in FIG. The light emission pulse is set to the H level (light emission) only for T1, for example, 5 μS, and is set to the L level (light emission stop) for T2, for example, 125 μS, and the duty ratio at this time is set to the first duty ratio. The light emitting pulse is applied to the light emitting circuit 2, and the light emitting element 3 is driven only during T1.
When the light receiving element 4 receives this light through the object detection area, it inputs the light to the microcomputer 1 via the light receiving circuit 5 and the amplifier unit 6. In microcomputer 1, A /
The A / D conversion is performed by the D conversion unit 1b as shown in step S3 of FIG.
Perform conversion processing. Next, in step S4, the on / off determination process is performed by the determination processing unit 1c. Then, in step S5, display processing and output processing are performed based on the determination result. In the output processing unit 1e, a determination signal indicating the presence or absence of an object or the like is output to the outside via the output unit 7. The display processing unit 1f outputs an output to the display unit 8 so that the light receiving level is displayed on the level display unit 8a and the threshold is displayed on the threshold display unit 8b. When an object is detected, an output is output to the display unit 8 so that the display element 8c for object detection is turned on.

The threshold value display section 8b displays the level of the threshold value set at that time. The threshold value display section 8b normally lights the element at the intermediate position, and within a certain upper and lower range, for example ± 18.
If there is light reception in the% range, the level is displayed on the level display section 8a as shown in FIG. When the light receiving level exceeds the threshold, an object detection signal is output, and the display element 8c is turned on. In the transmission type photoelectric sensor, the inverted value of the light receiving level is displayed as a level, and the object detection signal is turned on when the light blocking level is high and exceeds the threshold value.

Next, when adjusting the optical axis, first, the mode changeover switch 9a of the input section 9 is switched to the "TEACH" side.
This starts the processing in the sensitivity setting mode as shown in FIG. In the sensitivity setting mode, first, in step S11,
In S12, it is determined whether or not it is a period of burst light emission and no light emission. If it is a burst light emission period, the process proceeds from step S11 to step S13 to generate a light emission pulse of burst light emission having a duty ratio sufficiently larger than the duty ratio of the operation mode. If it is a non-light emitting period, the process proceeds from step S12 to step S14 to perform no light emitting processing. If it is not any of these light emitting periods, it is a sampling light emitting period, so a sampling light emitting process is performed for a certain period of time (step S15). In this way, a light emission pulse which repeats burst light emission, no light emission, and sampling light emission period is generated. FIGS. 5B and 5C show light emission pulses in this sensitivity setting mode. FIG. 5B shows the same time scale as FIG. 5A, and FIG. The axis is reduced to show the same light emission pulse. As shown in FIG. 5B, in the burst light emission period T5, the light emission of T3 and the light emission stop of T3 'are each set to, for example, 125 .mu.S, and the burst light emission is performed at a duty of 50%. In the subsequent non-light emission period T6, the light emission pulse is kept at the L level to stop the light emission. After the non-light emission period, a sampling light emission period T7 smaller than the first duty ratio of the operation mode is provided. The sampling light projection period T7 is, for example, T1 (5 μS), which is the same as the operation mode, and the stop period is T4, which is sufficiently longer than T2, for example, 1250 μS.

By repeating these three periods T5, T6, T7, a light projection pulse as shown in FIG. 5C is generated as a whole. The burst light emission period T5 becomes brighter in order to make the duty ratio sufficiently larger than that in the normal light emission, and at this time, the light emission spot is set to a sufficiently long time, for example, 200 mS. Also, burst light emission period T5
Since the duty ratio is large, the user's visual perception is continuously recognized as bright as shown in FIG. 5D, and becomes dark in the next non-light projection period T6 and sampling light projection period T7. Be recognized.

Since such light projection is repeated, FIG.
As shown in (a), in the case of a transmission type photoelectric sensor, a bright spot light is emitted from the light emitting unit to the light receiving unit side, so that the optical axis adjustment of the light emitting and receiving unit can be performed relatively easily. Further, as shown in FIG. 7B, in the case of a reflection type photoelectric sensor,
With respect to the object to be detected, the light emitting / receiving section or the head of the fiber unit connected to the light emitting / receiving section can be arranged at a predetermined position, and the light emitting spot can be accurately adjusted.

As shown in FIGS. 5A and 5B, the sampling light emission period T7 following the burst light emission has a smaller duty ratio than the normal operation mode, and the period is greatly increased to about 10 times. doing. This is because it is not necessary to consider the response speed in the sensitivity setting mode, and it is sufficient to simply recognize the light receiving level. In the sampling light emitting period, display processing of the light receiving level is performed every time a signal is obtained according to the light emitting pulse in step S16.

Next, the light receiving level display processing in step S16 will be described in detail with reference to FIG. When this process starts, first, the light receiving level is held in the register R in step S31. Then, in a step S32, it is determined whether or not the peak value held in advance exceeds the level of the register R. In the first operation, since the peak value is at the zero level, the process proceeds to step S33 and the value of the register at that time is stored in the peak value register P1. Then, the process proceeds to step S34, and a value obtained by multiplying the peak value P1 by a predetermined coefficient μ of 1 or less, for example, 0.88 is set as the threshold value P2 of the peak range. Then, in step S35, the output display element 8c is turned on as a peak range display lamp. On the other hand, if the value of the register R is equal to or less than the peak value P1 in step S32, the process proceeds to step S36, and it is determined whether or not the value of the register R exceeds the threshold value P2 of the peak range. If it does not exceed this range, the process proceeds to step S37, where the received light level R is displayed on each level display element 8a,
Next, in step S38, the peak value P1 is displayed on the threshold value display element 8b. If it exceeds this range, the process proceeds to step S35, where the display element 8c is turned on, and step S37 is performed.
Proceed to. In this manner, if the light reception level, the peak value, and the peak value are within the range, the fact is displayed and the display processing is completed.
Here, the microcomputer 1 performs steps S32 and S3.
3, the function of the peak value holding means 1j for holding the peak value is achieved, and the function of the peak range display means 1i for displaying the peak range is achieved in steps S34 to S36. In step S37, the function of the display means 1g for displaying the level is achieved, and in S38, the function of the peak value display means 1h for displaying the peak value is achieved.

The process proceeds to step S17 in FIG. 6 to determine whether or not the teaching switch 9a is turned on. If the teaching switch 9a is turned on, teaching is performed from the light receiving level at that time, and an appropriate threshold is set (step S1).
8). Then, in step S19, it is determined whether or not the mode has been switched to the operation mode. If the mode has been switched, the processing in the operation mode shown in FIG. 4 is performed.

Even if burst light emission, no light emission, and sampling light emission as shown in FIG. 5C are repeated, the temperature of the light emission circuit 2 gradually rises. A certain time T8 from the start, for example, 10
Determine if the minutes time has elapsed. Fixed time T
If 8 has not elapsed, the process returns to step S11 and the same processing is repeated. If the time T8 has elapsed, burst emission is not performed, and the process returns to step S15 to repeat only sampling emission. In this way, the projection spot cannot be confirmed after T8, but the display of the light reception level and the teaching can be performed.

Next, the operation of adjusting the optical axis by such display will be described with reference to FIG. When the photoelectric sensor according to this embodiment is a transmission-type photoelectric sensor and the light emitting and receiving units are opposed to each other, the light from the light emitting unit is strongly emitted during the burst light emitting period T5, so that rough optical axis adjustment becomes easy. After the burst light emission, light is emitted at a constant period during the sampling light emission period, and the light reception level at that time is A / D.
A / D conversion is performed by the conversion unit 1b, and light reception level display processing is performed. The display of the received light level at this time is shown in FIG.
As shown in (c), a full range is displayed, and non-linearly displayed so that the magnification of each level gradually increases. Therefore, for example, when the optical axis alignment is started as shown in FIG. 7A, a low light receiving level is displayed as shown in FIG. 9A, and the peak value at that time is displayed in the threshold display section 8b.
Are displayed by triangular LEDs. Here, when the light projecting unit or the light receiving unit is displaced so that the optical axes coincide, the light receiving level increases in accordance with the degree of coincidence of the optical axes.
As shown in (b), the light reception level and the peak value display increase. When the optical axis is farthest from the point where the optical axis coincides with the previous operation, only the held peak value P1 is displayed at the original level of the threshold value display section 8b as shown in FIG. 9C. The light receiving level is displayed at a low level on the level display section 8a. Therefore, the position of the light emitting and receiving device is finely adjusted so as to approach the held peak value again. A predetermined range including the peak value P1 thus held, that is, the peak value P
If it is within the range of 12% lower than 1, step S35
The peak range indicator lights as shown in FIG. FIG.
(D) shows this state, from which it can be recognized that the optical axes coincide. Here, the display of the light reception level is displayed in the full range, and the levels are non-linear, so that the distance between the light emitter and the light receiver in a transmission photoelectric sensor or a transmission photoelectric sensor using an optical fiber is reduced. This is almost proportional, and the optical axis can be easily adjusted.

In this embodiment, the teaching mode and the operation mode are switched by the mode switch 9a. However, the operation mode, the teaching mode, and the projection spot confirmation mode are switched by the switch. Is also good. In addition to returning to the operation mode by the mode changeover switch, the operation mode may be automatically returned to after the teaching is completed, or the burst lighting or the high power lighting may be automatically stopped after the teaching is completed.

In this embodiment, the level display section 8a and the threshold value display section 8b which are already provided in the photoelectric sensor are used as display elements for displaying the level display and the peak display at the time of setting the sensitivity. A separate level indicator for use may be provided. Alternatively, either one of the light receiving level and the peak value may be displayed, and the peak value and the level of the characteristic amount may be displayed by using a single level indicator using two-color light emitting diodes.

In this embodiment, a photoelectric sensor for detecting the presence or absence of an object has been described. However, the present invention can be applied to other types of photoelectric sensors for detecting the physical state of an object. For example, the present invention is applied to a sensor that separates reflected light or transmitted light and detects the color of a mark attached to an object, or a color mark sensor that detects a light receiving level for each wavelength using a plurality of wavelengths as a light source. Can be. Also, the direction of polarization of the light emitting element serving as a light source is only P-polarized light or S-polarized light,
It is also possible to apply the present invention to a photoelectric sensor that detects the glossiness of a detection object from the difference or ratio of the amount of received P-polarized light or S-polarized light by splitting the reflected light by a polarization beam splitter through a half mirror for each polarization component. . Further, the present invention can be applied to a photoelectric sensor or the like which discriminates the degree of gloss at a predetermined threshold value and detects the presence or absence of gloss, the surface roughness, the state of unevenness, the combination of color and gloss, the presence or absence of painting, and the like. In these photoelectric sensors, in the sensitivity setting mode, the light receiving level is displayed on the level display section 8a which displays the level of the characteristic amount after processing the light receiving level in the operation mode.

[0029]

As described above in detail, according to the first and second aspects of the present invention, the light reception level is displayed at the time of optical axis adjustment by the first group of level display elements. At the time of adjustment, it is possible to easily recognize how much the optical axes match. In the third and fourth aspects of the present invention, since the peak value of the light receiving level is displayed on the second group of display elements, the optical axis can be easily adjusted so as to coincide with the peak value. Further, in the invention of claim 5, the peak range is displayed when a light receiving level within a predetermined range is obtained from the peak value once the peak value is obtained. Is displayed, it can be recognized that the optical axes match,
The effect is obtained that the user can recognize the end of the optical axis adjustment.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a panel surface of the photoelectric sensor according to the embodiment.

FIG. 3 is a block diagram showing functions of a display processing unit and a display unit of the photoelectric sensor according to the embodiment.

FIG. 4 is a flowchart showing processing of the microcomputer in an operation mode.

FIG. 5 is a time chart showing light emission pulses in an operation mode and a sensitivity setting mode.

FIG. 6 is a flowchart illustrating a process in a sensitivity setting mode.

FIG. 7 is a perspective view showing a state of optical axis adjustment of a transmission photoelectric sensor and a reflection photoelectric sensor.

FIG. 8 is a flowchart illustrating an operation of a light reception level display process.

FIG. 9 is a diagram illustrating a display example in a light reception level display process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 1a Projection processing part 1b A / D conversion part 1c Judgment processing part 1d Teaching processing part 1e Display processing part 1f Output processing part 1g Level display means 1h Peak value display means 1i Peak range display means 1j Peak value holding means 2 Light emitting circuit 3 Light emitting element 4 Light receiving element 5 Light receiving circuit 6 Amplifier section 7 Output section 8 Display section 8a Level display section 8b Threshold display section 8c Output display element 9 Input section 9a Mode switch 9b Teaching switch 9c Output mode switch

Claims (5)

[Claims] 1. A light emitting unit having a light emitting element and emitting light, a light receiving unit receiving light emitted from the light emitting unit through a detection area, and a characteristic amount determined based on a light receiving level A first group of level display elements for displaying the level of the feature amount, and a second group of levels for displaying the threshold in correspondence with the first group of level display elements A photoelectric sensor having a display element, comprising: a level display means for displaying a level received by the light receiving unit at the time of optical axis adjustment by the first group of level display elements. 2. A light emitting unit having a light emitting element and emitting light, a light receiving unit receiving light emitted from the light emitting unit via a detection area, and a characteristic amount determined based on a light receiving level. A first group of display elements for displaying the level of the feature amount and a second display for level display of the set threshold value in association with the first group of display elements. In a photoelectric sensor having an element group, a peak value holding unit that holds a peak value of a level received by the light receiving unit at the time of optical axis adjustment, and a peak value level held by the peak value holding unit is set in the second group. And a peak value display means for displaying on the level display element. 3. A light emitting unit having a light emitting element and projecting light, a light receiving unit receiving light emitted from the light projecting unit via a detection area, and a characteristic amount determined based on a light receiving level. And a signal processing means for discriminating the level by a predetermined threshold value, comprising: a level display element for displaying a level received by the light receiving section at the time of optical axis adjustment by a level display element. 4. A light emitting unit having a light emitting element and emitting light, a light receiving unit receiving light emitted from the light emitting unit via a detection area, and a characteristic amount determined based on a light receiving level. A signal processing unit that discriminates a peak value at a predetermined threshold value, a peak value holding unit that holds a peak value of a level received by the light receiving unit at the time of optical axis adjustment, and a peak value held by the peak value holding unit. A peak value display means for displaying the level of the peak value on the level display element. 5. A light emitting unit having a light emitting element and emitting light, a light receiving unit receiving light emitted from the light emitting unit through a detection area, and a characteristic amount determined based on a light receiving level. Signal processing means for discriminating a threshold value with a predetermined threshold value, a peak value holding means for holding a peak value of a level received by the light receiving unit at the time of optical axis adjustment, and a display for displaying an operation state during operation Means for displaying a peak range when a light receiving level within a certain range including the peak value held by the peak value holding means at the time of optical axis adjustment is obtained. Characteristic photoelectric sensor.