JP2010197290A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device that facilitates obtaining decision results corresponding to a geometric characteristic of an object passing through a detection target region. <P>SOLUTION: The sensor device includes a photoelectronic sensor body for obtaining an output corresponding to a light reception quantity, a decision section that determines whether a time period T wherein the output from the sensor body exceeds a preset output threshold Ts satisfies a condition whether the time period T is continued over a preset time width Tt, and an output circuit that is started when the decision section determines that the condition is satisfied so as to output a preset signal to the outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor device.

  A photoelectric sensor device is known as an object detection device that determines the presence or absence of the detection target using a sensor that obtains an output corresponding to the physical quantity of the detection target. This type of photoelectric sensor device basically includes a light projecting unit that irradiates light toward a detection region of an object, and light that has passed through the detection region of light emitted from the light projecting unit. A so-called photoelectric sensor head including a light receiving unit that receives the reflected light and obtains a sensor output corresponding to the received light amount, and compares the received light amount at the light receiving unit with a preset threshold T. A determination unit (comparator) for outputting the comparison result and an output unit for externally outputting a signal corresponding to the comparison result in the determination unit are configured.

  Incidentally, the so-called transmission type photoelectric sensor device that detects light that has been irradiated from the light projecting unit and transmitted through the detection target region by the light receiving unit is that light is blocked by an object that exists in the detection target region. Used for object detection. Further, in the so-called reflection type photoelectric sensor device in which light received from the light projecting unit and reflected by the detection target region is detected by the light receiving unit, light is reflected by an object existing in the detection target region. (For example, refer to Patent Document 1).

JP-A-7-221623

  By the way, the conventional photoelectric sensor device generally only determines the magnitude by comparing the amount of received light with a preset threshold value. However, it can detect objects by capturing shape features such as size and color of the object, detect that multiple objects with different shapes have passed through the detection area in a predetermined order, or detect multiple objects at predetermined intervals. I often want to detect that has passed. In order to satisfy such various demands, conventionally, a plurality of photoelectric sensor devices are exclusively used, and a control device such as a PLC (programmable logic controller) is used, and each output of the plurality of photoelectric sensor devices is transmitted by the PLC. The determination result is obtained by logical processing / order processing. However, it cannot be denied that the configuration becomes complicated and the apparatus cost increases.

  The present invention has been made in consideration of such circumstances, and the object of the present invention is to control a determination result corresponding to the shape characteristic of an object passing through the detection target region, such as a PLC (programmable logic controller). An object of the present invention is to provide a sensor device having a simple configuration that can be easily obtained without using the device.

According to the present invention, when detecting an object passing through the detection target region, the detection condition can be changed according to the shape characteristic of the object by changing a threshold for the sensor output, and the shape of the object The special feature is made by paying attention to the fact that it can be understood as a change with time of the sensor output.
Therefore, in order to achieve the above-described object, the sensor device according to the present invention basically includes
<a> a sensor body that obtains an output of a level corresponding to the physical quantity of the detection object;
<b> Judgment means for judging whether or not a period in which the level of the output from the sensor body exceeds a preset level threshold satisfies a condition for continuing over a preset time width;
<c> An output circuit that is activated when the determination unit determines that the condition is satisfied and outputs a preset signal to the outside is provided.

Another sensor device according to the present invention is as follows:
<a> a sensor body that obtains an output of a level corresponding to the physical quantity of the detection object;
<b> Judgment means for judging whether or not a period in which the level of the output from the sensor body exceeds a preset level threshold satisfies a condition for continuing over a preset time width;
<d> Determination condition changing means for changing the condition given to the determination means by changing the level threshold and / or time width when it is determined by the determination means that the condition is satisfied;
<e> After changing the condition for a preset number of times, further comprising an output circuit that is activated when the determination means determines that the condition is satisfied, and outputs a preset signal externally It is characterized by that.

Still another sensor device according to the present invention is:
<a> a sensor body that obtains an output of a level corresponding to the physical quantity of the detection object;
<b1> The first condition is whether or not a period in which the level of the output from the sensor body exceeds a preset first level threshold value over a preset first time width is the first condition. First determination means for determining whether or not the condition of
<b2> A period of time when the output level from the sensor main body exceeds a preset second level threshold that is activated when it is determined by the first determination means that the first condition is satisfied. Second determination means for determining whether or not to continue over the set second time width;
<c> An output circuit that is activated when the second determination means determines that the second condition is satisfied and outputs a preset signal to the outside is provided.

  Incidentally, the determination means, for example, compares the level of the signal output from the sensor main body with the level threshold value and outputs the comparison result, and the output of the level comparison means over the predetermined time width. This is realized as having time comparison means for determining whether or not to continue. The sensor main body receives, for example, reflected light or transmitted light of the light irradiated to the detection target region, captures the received light amount as a physical quantity of the detection target, and outputs a current or voltage corresponding to the received light amount. Consists of.

  According to the sensor device of the present invention, it is possible to easily and effectively determine various geometric features of a detection target by capturing changes with time in the output of the sensor body.

1 is a schematic configuration diagram of a photoelectric sensor device according to a first embodiment of the present invention. FIG. 2 is a timing chart for explaining a detection operation of the photoelectric sensor device shown in FIG. 1. The schematic block diagram of the photoelectric sensor apparatus which concerns on the 2nd Embodiment of this invention. The figure which shows the example of a detection of the shape characteristic of the object by the photoelectric sensor apparatus shown in FIG. The schematic block diagram of the photoelectric sensor apparatus which concerns on the 3rd Embodiment of this invention.

Hereinafter, with respect to a sensor device according to an embodiment of the present invention with reference to the drawings, a light projecting unit irradiates a detection target region through which an object passes at a constant speed, and receives reflected light from the detection target region. An example of a photoelectric sensor device that receives light and determines the amount of light received and detects an object of a predetermined size will be described.
FIG. 1 is a schematic configuration diagram of a main part of a sensor device according to a first embodiment of the present invention. Reference numeral 1 includes a light projecting unit 2 and a light receiving unit 3, and outputs according to the amount of light received by the light receiving unit 3. It is a sensor body to obtain. Incidentally, the sensor output is composed of a voltage signal corresponding to the amount of light received by the light receiving unit 3, for example. If the light receiving unit 3 is of a type that outputs a current signal corresponding to the amount of received light, the current signal is What is necessary is just to obtain a sensor output by voltage conversion.

  The determination means 4 for determining the output of the sensor main body 1 is such that the period T in which the magnitude S of the output from the sensor main body 1 exceeds the preset output threshold Ts continues over the preset time width Tt. It is determined whether or not a determination condition given as to whether or not to perform is satisfied. Specifically, the determination unit 4 compares the sensor output magnitude S with a preset output threshold Ts, and when the sensor output magnitude S exceeds the output threshold Ts, the determination result of the H level. And a comparator 5 that outputs an L-level determination result when the magnitude S of the sensor output is less than the output threshold value Ts. On the contrary, the comparator 5 outputs an L level determination result when the sensor output level S exceeds the level threshold value Ts, and when the sensor output level S is less than the level threshold value Ts. It is also possible to use one that outputs an H level determination result. Which determination result is to be obtained is determined according to the difference between the sensor body 1 being a reflection type or a transmission type and its detection specification.

  The determination means 4 receives the determination output of the comparator 5 and, for example, measures a time circuit 6 for measuring the output time width T of the determination result of the H level, and the determination result timed by the time measurement circuit 6. The comparator 7 compares the duration (time width) T with a preset time width threshold value Tt. The time measuring circuit 6 is composed of a counter for obtaining the duration T by counting the reference clock from the clock source 8 over a period in which the judgment output of the comparator 5 is at the H level, for example. The duration T of the determination result of the H level measured by the time measuring circuit 6 is given to the comparator 7 as a trigger when the output of the comparator 5 is inverted to the L level and set in advance. Is compared with the set time width threshold Tt. The time measuring circuit 6 is reset after outputting the duration (time width) T of the determination result timed as described above to the comparator 7 for comparison with the time width threshold value Tt.

  The comparator 7 outputs an H level determination result when, for example, the duration width T exceeds the duration threshold value Tt, and when the duration time T is less than the duration threshold value Tt, The determination result at the L level is output. The comparator 7 may obtain a determination result obtained by reversing the logic. Further, the comparator 7 may obtain a determination result when the duration time T matches the time width threshold value Tt including a predetermined allowable error. In this case, a first time width threshold value Tt1 and a second time width threshold value Tt2 are given, and the duration time T is defined by the first and second time width threshold values Tt1 and Tt2. It may be determined whether or not it falls within the range [Tt1 to Tt2].

  That is, the determination means 4 configured as described above determines whether or not the output magnitude S corresponding to the amount of light received by the sensor body 1 exceeds the preset output threshold value Ts in the comparator 5. In the device 7, whether the period T during which the output magnitude S exceeds the preset output threshold value Ts exceeds the preset time width threshold value Tt, or corresponds to the time width threshold value Tt. It is to be judged. The output circuit 9 is activated in response to the output of the comparator 7 and is preset when a sensor output that satisfies the determination conditions given as the output threshold value Ts and the time width threshold value Tt is obtained. An output signal of the specification, that is, a pulse signal having a predetermined signal intensity and a predetermined time width is generated and output as a sensor output to the outside. Such an output circuit 9 is realized as a timer circuit such as a one-shot multivibrator.

  Thus, according to the sensor device configured as described above, the light receiving amount of the light receiving unit 3 that receives the reflected light from the object passing through the detection target region at a constant speed, as shown in FIG. However, when it changes as shown in FIG. 2A, the comparator 5 that compares the output magnitude S of the sensor body 1 corresponding to the received light amount with a preset output threshold value Ts is shown in FIG. As shown, an H level determination signal is output over a period in which the output magnitude S exceeds the output threshold Ts. Then, the timer circuit 6 counts the clock signal over the output period of the determination signal as shown in FIG. 2C, and obtains the duration widths T1, T2, and T3, respectively.

  For the periods (duration durations) T1, T2, T3 in which the output magnitude S thus obtained exceeds the output threshold value Ts, the comparator 7 compares it with a predetermined time width threshold value Tt. Only when the duration time T1, T2, T3 of the determination signal corresponds to the time width threshold value Tt, the determination signal is output as shown in FIG. As a result, the output circuit 9 is provided only when the determination result is obtained from the comparator 7, that is, the period in which the amount of received light exceeds the preset output threshold value Ts extends over the preset time width threshold value Tt. Only when it continues, as shown in FIG. 2E, a pulse signal having a predetermined time width is generated and output as a sensor output.

  Therefore, according to the photoelectric sensor device, it is possible to reliably detect only an object having a predetermined shape (size) passing through the detection target region at a constant speed. In addition, it is possible to easily detect an object having a predetermined shape characteristic by determining not only the magnitude of the received light amount but also the duration for which the predetermined received light amount is obtained. Note that the reflectance changes depending on the color of the object, and the amount of light received by the light receiving unit 3 changes accordingly. Therefore, the amount of light received by the reflected light itself can be understood as a shape feature of the object. Therefore, by setting the output threshold value Ts for determining the amount of received light according to the color of the object, it is possible to determine the shape feature.

  By the way, as an object detection condition, for example, there is a case where it is desired to detect an object whose shape characteristics change depending on the part. In some cases, it is desired to detect a state in which objects having different shape characteristics pass through the detection target region in a predetermined order. However, in the photoelectric sensor device described above, it is difficult to execute the detection process alone. Then, the example of the photoelectric sensor apparatus suitable for the use mentioned above is demonstrated.

  FIG. 3 is a schematic configuration diagram of a main part of a photoelectric sensor according to the second embodiment of the present invention. In this photoelectric sensor device, determination condition changing means for sequentially changing the output threshold value Ts and / or the time width threshold value Tt given to the determination unit 4 in response to the output of the determination unit 4 in the photoelectric sensor device shown in FIG. 10 and is configured to activate the output circuit 9 according to the output of the determination unit 4 after the output threshold value Ts and / or the time width threshold value Tt has been changed over a preset number of times n. .

  That is, the determination condition changing unit 10 continues the light reception amount determined by the determination unit 4 configured as described above under the preset output threshold value Ts over the preset time width threshold value Tt. In response to the determination result that is sometimes output, the output threshold Ts and / or the time width threshold Tt in the determination unit 4 is changed, and the output from the sensor body 1 is determined again under the changed threshold condition. . Incidentally, whether to change the output threshold value Ts or the time width threshold value Tt is determined according to the detection target, and only one of them may be changed or both may be changed simultaneously.

  Specifically, the determination condition changing means 10 includes a memory 11 that stores an output threshold value Ts and a time width threshold value Tt set in the determination unit 4 in a predetermined order, and receives the output of the determination unit 4 each time. A function of sequentially setting the output threshold value Ts and / or the time width threshold value Tt stored in the memory 11 in the determination unit 4; The determination condition changing means 10 manages the number of changes of the output threshold Ts and / or the time width threshold Tt given to the determination unit 4 and stores the output threshold Ts and / or the time width threshold stored in the memory 11. A change number managing means 12 for controlling the reading of Tt and controlling the output circuit 9 to be operable is provided.

  Further, the determination condition changing means 10 monitors whether or not the next determination output is obtained from the determination unit 4 within a predetermined time after changing the output threshold Ts and / or the time width threshold Tt. The timer / reset circuit 13 is provided for resetting the judgment condition changing means 10 and the judgment unit 4 when the next judgment result is not obtained within the time period. For example, even if the determination unit 4 obtains a predetermined determination result under the previously set determination condition by the timer / reset circuit 13, the determination condition is changed under the determination condition. When the determination unit 4 cannot obtain a determination result within a predetermined time, all of them are reset and returned to the initial state.

  According to the photoelectric sensor device configured in this way, the amount of received light S at the sensor body 1 changes as shown in FIG. 4A due to the shape characteristics of the object. Even if it exists, the change with time can be reliably detected only by changing the output threshold value Ts and the time width threshold value Tt in order. Moreover, the shape feature of the object can be easily determined simply by sequentially changing the output threshold Ts and / or the time width threshold Tt set in the determination unit 4 according to the determination result under a certain condition.

  Further, even when a plurality of objects sequentially pass through the detection target region, and the amount of light received by the sensor body 1 changes as shown in FIG. 4B, this can be reliably detected. . At this time, if a state in which the amount of received light is less than the predetermined output threshold value Ts is detected as a state in which no object is present, and the time width Td is determined, a plurality of images that sequentially pass through the detection region at a constant speed. It is also possible to determine the spacing between objects.

  Then, while sequentially changing the determination conditions as described above, a pulse signal having a predetermined time width is generated from the output circuit 9 according to the output of the determination unit 4 obtained when all of the determination conditions are satisfied, and externally output. Therefore, it is possible to easily drive a control target device such as a solenoid valve by directly using the output of the photoelectric sensor device without using an external device such as a PLC (programmable logic controller). .

  In addition, as shown in FIG. 5 according to the third embodiment of the present invention, a first determination unit 4a and a second determination unit 4b in which determination conditions are individually set are provided, and the first determination unit 4a has a predetermined value. It is also possible to activate the second determination unit 4b only when a determination result is obtained, and to activate the output circuit 9 according to the determination result by the second determination unit 4b. In this case, the first output threshold Ts1 and the first time width threshold Tt1 are set in the first determination unit 4a, and the second output threshold Ts2 and the second time are set in the second determination unit 4b. The width threshold value Tt2 may be set. Then, the selection circuit 15 that operates in response to the output of the first determination unit 4a may be used for selection control so that the first and second determination units 4a and 4b are complementarily driven. It is of course possible to extend the third embodiment to provide three or more determination units and to sequentially drive these determination units.

  In addition, this invention is not limited to each embodiment mentioned above. For example, in an apparatus using a transmissive photoelectric sensor, it is possible to detect a received light amount that does not satisfy a preset output threshold value Ts. According to such a photoelectric sensor device, it is useful when detecting a translucent object having a shape feature such that the light transmittance partially changes. Further, for the judgment output of the comparator 5, the duration when the output is at the H level and the duration when the output is at the L level are respectively measured. In the comparator 7, each of these durations is measured. It is also possible to configure so as to be a determination condition. Further, the comparator 5 may be configured to detect the received light amount of [Tsa to Tsb] within the range defined by the two output threshold values Tsa and Tsb.

  In addition, although the photoelectric sensor has been described here as an example, the same applies to a case where an electric quantity such as voltage or current changes depending on an object passing through the detection target region, for example, based on an output of a high frequency proximity sensor. Is possible. In addition, the present invention can be variously modified and implemented without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Sensor main body 2 Light projection part 3 Light reception part 4, 4a, 4b Judgment part 5 Comparator (size judgment of sensor output)
6 Timekeeping circuit 7 Comparator (Time width judgment)
8 Clock source 9 Output circuit 10 Judgment condition change section

Claims (6)

A sensor body for obtaining an output corresponding to the physical quantity of the detection object;
Determining means for determining whether or not a period in which the output from the sensor body exceeds a preset threshold value satisfies a condition for continuing over a preset time width;
An output circuit that is activated when the determination means determines that the condition is satisfied, and outputs a preset signal to the outside. A sensor body for obtaining an output corresponding to the physical quantity of the detection object;
Determining means for determining whether or not a period in which the output from the sensor body exceeds a preset threshold value satisfies a condition for continuing over a preset time width;
A determination condition changing means for changing the threshold and / or time width to change the condition given to the determination means when it is determined by the determination means that the condition is satisfied;
After changing the condition over a preset number of times, further comprising an output circuit that is activated when the determination means determines that the condition is satisfied, and outputs a preset signal externally A characteristic sensor device.   The determination means compares the magnitude of the signal output from the sensor body with the threshold value and outputs the comparison result, and the output of the signal comparison means continues over the predetermined time width. The sensor device according to claim 1, further comprising time comparison means for determining whether or not. A sensor body for obtaining an output corresponding to the physical quantity of the detection object;
Whether the period in which the output from the sensor body exceeds a preset first threshold value continues over a preset first time width is a first condition, and whether the first condition is satisfied First determination means for determining whether or not;
A period of time when the output from the sensor body exceeds a preset second threshold is started when it is determined by the first determining means that the first condition is satisfied. Second determination means for determining whether or not to continue over the width;
An output circuit that is activated when the second determination means determines that the second condition is satisfied, and outputs a preset signal to the outside.   The first and second determination means are a signal comparison means for comparing the magnitude of the signal output from the sensor body with the threshold value and outputting the comparison result, and the output of the signal comparison means is the predetermined time. The sensor device according to claim 4, further comprising time comparison means for determining whether or not to continue over a period of time.   5. The sensor device according to claim 1, wherein the physical quantity of the detection target is a light amount, and the sensor is an optical sensor that outputs a current or a voltage corresponding to the amount of received light.

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