JP2007124373A - Detection sensor and photoelectric sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric sensor where the number of components can be reduced. <P>SOLUTION: A photodetection signal Si output according to a photodetection amount from a photodetective circuit 15 is input to a CPU 13 to be compared with a threshold (a) and a threshold (b) having a prescribed hysteresis band by a second discrimination means 16B within the CPU 13 and to be compared with a threshold (c) set between the threshold (a) and the threshold (b) by a first discrimination means 16A. Then, both of the two discrimination means 16A and 16B output a signal at a low level when the level of the photodetection signal Si is not lower than a threshold, but output a signal at a high level when the level of the photodetection signal Si is not higher than the threshold. An output circuit 17 outputs an output signal Pe at a high level when a pulse signal P2 of the second discrimination means 16B is at a high level when a pulse signal P1 of the first discrimination means 16A rises. It is possible to judge that a metal ball Wb is an excellent product from the output signal Pe. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a detection sensor and a photoelectric sensor.

  Conventionally, for example, a detection sensor (photoelectric sensor) for detecting a state of a detection target or the like is known. For this type of detection sensor (photoelectric sensor), for example, among the light projected from the light projecting element toward the detection object, the amount of light received by the light receiving element is compared with a predetermined threshold, Some of them output either a high level signal or a low level signal according to the comparison result.

Then, for example, as shown in FIG. 8, a light reception signal obtained by a light projecting / receiving operation performed by a plurality of detection sensors (photoelectric sensors) 1... 1 is output to the controller 2, and a predetermined logical operation is performed by the controller 2. By doing so, the state or the like of the detection object is detected based on the calculation result.
JP-A-5-276006

By the way, when detecting the state or the like of the detection target object, the state of the detection target object may be determined using a special algorithm instead of using a simple logical operation. In such a case, when performing arithmetic processing or the like using a device separate from the detection sensor (photoelectric sensor) 1, the number of parts increases, and the management cost increases accordingly. was there.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a detection sensor and a photoelectric sensor capable of reducing the number of parts.

  As means for achieving the above object, the invention of claim 1 is based on a physical quantity detection means for outputting a detection signal at a level corresponding to a physical quantity of a detection target, and a detection signal from the physical quantity detection means, respectively. A plurality of discriminating means for outputting discrimination results according to different setting conditions, and output from other discriminating means when a discrimination result output from one of the plurality of discriminating means changes. It is characterized in that it is configured to include an output means for outputting an output signal corresponding to the discrimination result.

  According to a second aspect of the present invention, the detection sensor according to the first aspect is configured to receive light from a light projecting unit that projects light and the light projecting unit, and to receive a light reception signal corresponding to the received light amount as the detection signal. A plurality of determination means, the first determination means as the first determination means and the second determination means as the other determination means. And the output means outputs as a determination result from the second determination means at the rise or fall of the pulse signal output as the determination result from the first determination means. The output signal is output based on the level of the pulse signal to be output.

  According to a third aspect of the present invention, in the second aspect, the setting condition in the determination unit is a threshold value, and both of the two determination units have a low level when the light reception signal level is equal to or higher than the threshold value. While the signal is output, a high level signal is output when the received light signal level is equal to or lower than the threshold value, and the threshold value in the second determination means has a first hysteresis width and a second hysteresis width having a predetermined hysteresis width. The threshold value in the first determination means is a third threshold value set between the first and second threshold values.

  According to a fourth aspect of the present invention, in the second aspect, the setting condition in the determination unit is a change amount of the level of the light reception signal, and the first determination unit is a predetermined time of the level of the light reception signal. A high level signal is output when the amount of increase per unit is greater than or equal to a predetermined level, and the second determining means outputs a high level when the amount of decrease in the level of the received light signal per predetermined time is greater than or equal to a predetermined level. The level signal is continuously output for a predetermined continuous output time, and the output means raises the output signal from the first determination means when the signal from the second determination means is at a high level. The condition is that a high-level output signal is output.

  The invention according to claim 5 is characterized in that, in the apparatus according to claim 4, there is provided setting means capable of setting the continuous output time in the second determination means.

  According to the present invention, the output means outputs an output signal corresponding to another discrimination result when the discrimination result output from one discrimination means changes. Therefore, it is not necessary to provide a device or the like for executing the processing separately from the photoelectric sensor, and the number of parts can be reduced.

<Embodiment 1>
Embodiment 1 of the present invention (corresponding to the invention of claim 3) will be described with reference to FIGS.
As shown in FIG. 1, the photoelectric sensor 10 according to the first embodiment detects a metal ball Wb (non-defective metal ball) having a predetermined reflectance in a conveyance line in which metal balls Wb (objects to be detected) are sequentially conveyed. This is a so-called reflective photoelectric sensor.

Next, the electrical configuration of the photoelectric sensor 10 is shown in FIG.
Reference numeral 13 in FIG. 2 denotes a CPU. The photoelectric sensor 10 includes a CPU 13, a light projecting element 11, a light projecting circuit 12 that receives a light projecting signal Sa from the CPU 13 and emits light from the light projecting element 11 (for example, LED, laser diode), and the light projecting element 11. The light receiving element 14 (for example, a photodiode) that receives the light reflected from the metal ball Wb among the light projected from the light and the light reception signal (detection signal) based on the amount of light received by the light receiving element 14 And a light receiving circuit 15 for outputting to the CPU 13. The light projecting element 11 and the light projecting circuit 12 correspond to “light projecting means” of the present invention, and the light receiving element 14 and the light receiving circuit 15 correspond to “light receiving means, physical quantity detecting means” of the present invention.
The light receiving circuit 15 amplifies a signal corresponding to the amount of light received output from the light receiving element 14 and outputs an A / D converted light receiving signal Si to the CPU 13.

  The CPU 13 includes two determination means 16A and 16B that both receive the light reception signal Si from the light reception circuit 15, and an output circuit 17 that receives the pulse signals P1 and P2 from the two determination means 16A and 16B, respectively. It is configured.

  The two discriminating means 16A and 16B comprise a first discriminating means 16A (one discriminating means) and a second discriminating means 16B (other discriminating means), both of which are the levels of the light receiving signal Si output from the light receiving circuit 15. When the signal is equal to or higher than the threshold, a low level signal is output, while when the light receiving signal Si is equal to or lower than the threshold, a high level signal is output (so-called dark-on). Therefore, the threshold corresponds to the “setting condition” of the present invention, and the high level or low level signal output from the determination means 16A, 16B corresponds to the “determination result”.

  Here, the threshold values in the second determination unit 16B are a threshold value b (first threshold value) and a threshold value a (second threshold value) having a predetermined hysteresis width (an interval between the threshold value b and the threshold value a in FIG. 3). a <b), and these are switched in accordance with a change in the received light signal. The reason why the two types of threshold values are switched in this way is that when a certain threshold value (for example, only threshold value b) is set, if the light reception signal Si varies due to noise, the variation above and below the threshold value is repeated. This is because a so-called chattering phenomenon occurs and is undesirable.

  Specifically, as shown in FIG. 3, until the level of the light reception signal Si exceeds the threshold value b, the comparison between the threshold value b and the level of the light reception signal Si is performed by the second determination unit 16B. At this time, since the level of the light reception signal Si is smaller than the threshold value b, a high level signal (pulse signal P2) is output from the second determination unit 16B.

  On the other hand, when the level of the light reception signal Si exceeds the threshold value b, the setting is switched from the threshold value b to the threshold value a (the threshold value is lowered by the hysteresis width), and the comparison between the threshold value a and the level of the light reception signal Si is the second determination. This is done by means 16B. At this time, since the level of the light reception signal Si is larger than the threshold value a, a low level signal (pulse signal P2) is output from the second determination unit 16B.

  When the level of the light reception signal Si becomes equal to or lower than the threshold value a, the setting is switched from the threshold value a to the threshold value b (the threshold value is increased by the hysteresis width), and the comparison between the threshold value b and the level of the light reception signal Si is performed again. A high level signal is output from the discriminating means 16B.

The threshold in the first determination unit 16A is a threshold c (third threshold) set between the threshold a and the threshold b.
The comparison process in the first determination unit 16A and the comparison process in the second determination unit 16B are executed at a timing shifted by a minute time (non-overlapping timing).

  As shown in FIG. 2, the output circuit 17 (output means) is configured to receive the pulse signal P1 from the first discrimination means 16A and the pulse signal P2 from the second discrimination means 16B. .

  Then, as shown in FIG. 3, when the rise (change from low level to high level) of the pulse signal P1 output as the discrimination result from the first discrimination means 16A is detected, the discrimination result from the second discrimination means 16B at that time It is determined whether the pulse signal P2 output as is at a high level.

  When the output circuit 17 determines that the pulse signal from the second determination unit 16B is at the high level at the rising edge of the pulse signal P1 from the first determination unit 16A, the output circuit Pe ( (Pulse signal) is output to the outside.

  As a result, the high-level output signal Pe is output only when the level of the light reception signal Si is within a predetermined range, so that the metal ball Wb (non-defective metal ball) having a predetermined reflectance is output. ) Can be detected (no defective metal balls (metal balls having different reflectance due to discoloration or the like) are not detected).

  Thus, according to the present embodiment, when the pulse signals P1 and P2 are input to the output circuit 17 (output means), the determination result output from the first determination means 16A (one determination means) changes. An output signal Pe corresponding to the determination result by the second determination means 16B (other determination means) at this time is output from the output circuit 17. Therefore, it is not necessary to provide a device or the like for executing the processing separately from the photoelectric sensor, and the number of parts can be reduced.

<Embodiment 2>
A second embodiment (corresponding to the invention of claim 4) of the present invention will be described with reference to FIGS.
In the first embodiment, a reflection type photoelectric sensor that detects the amount of light reflected by the metal ball Wb out of the projected light is used. However, in the second embodiment, as shown in FIG. The front end portions F1a and F2a of F1 and F2 are opposed to each other, and have a light-transmitting glass substrate Wg or the like (for example, a glass wafer or the like) that is transported by a transport unit on the optical path between the front end portions F1a and F2a. This is a so-called transmissive photoelectric sensor 20 (fiber sensor) that detects a detection object based on a change in the amount of received light when the light passes. Here, since the glass substrate Wg (detection target) of the second embodiment has optical transparency, the CPU 13 does not detect the light incident state or the light shielding state in the light receiving element 14, but the glass substrate Wg is on the optical path. The glass substrate Wg is detected based on the change in the amount of received light when entering (exiting from the optical path). In addition, about the structure same as Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 5, in the photoelectric sensor 20, the light emitted from the light projecting element 11 is incident on one end side of the optical fiber F1. As a result, light is emitted from the tip portion F1a via the optical fiber F1 (see FIG. 4), and light incident from the tip portion F2a is irradiated to the light receiving element 14 via the optical fiber F2. Yes.

  The CPU 13 includes two determination units 26A and 26B that both receive the light reception signal Si from the light reception circuit 15, and an output circuit 17 that receives the pulse signals P1 and P2 from the two determination units 26A and 26B, respectively. It is configured.

  The two discriminating means 26A, 26B are composed of a first discriminating means 26A (one discriminating means) and a second discriminating means 26B (other discriminating means), both of which are provided with a differentiation circuit, and the level of the received light signal. A signal corresponding to the amount of change (setting condition) is output.

  As shown in FIG. 6, when the first discriminating means 26A detects that the level of the received light signal Si has increased by a predetermined level or more (changed in the increasing direction) within a unit time (predetermined time) by the differentiating circuit, (Pulse signal P1) is output only for a minute time T1.

  When the second discriminating means 26B detects that the level of the light reception signal Si has decreased by a predetermined level or more (changed in a decreasing direction) within a unit time (predetermined time) by the differentiating circuit, the high-level signal (pulse signal P2) Is output only for the continuous output time T2.

Here, the continuous output time T2 is a time determined based on the size (length) of the glass substrate Wr (detection target) serving as a reference and the transport speed of the glass substrate Wg by the transport means. Specifically, a time slightly longer than the time during which the glass substrate Wr serving as the reference passes on the optical path (from the pulse signal P2 becomes high level until the pulse signal P1 falls (becomes high level) next). Is slightly longer than the time).
As shown in FIG. 5, the photoelectric sensor 20 includes an input setting unit 29 (corresponding to “setting unit of the present invention”) that can be input by the user. By operating the input setting unit 29, various settings set by the CPU 13 can be changed. For example, the setting content (of the second determination unit 26B) includes the above-described continuous output time T2, but the input setting unit 29 can perform an input operation (setting change) for the continuous output time T2. In this case, a signal corresponding to an input operation from the input setting unit 29 is provided to the second determination unit 26B of the CPU 13. When receiving the information on the continuous output time T2 from the input setting unit 29, the second determination unit 26B sets the continuous output time T2 as a set value (stores it in a storage unit (not shown)). Thereby, even if it is a case where the glass substrate Wr of the reference | standard magnitude | size is changed into the glass substrate of another magnitude | size, or a translucent member of another magnitude | size, the glass substrate which becomes the reference | standard for continuous output time T2 It becomes possible to detect a different glass substrate or the like (translucent member) by setting the time to be determined based on the size of Wr (detection target) and the conveyance speed of the glass substrate Wg by the conveyance means. .

  The output circuit 17 (output means) receives the pulse signal P1 from the first discriminating means 16A and the pulse signal P2 from the second discriminating means 16B (see FIG. 5), and as shown in FIG. When it is determined that the pulse signal P2 is at the high level when the signal P1 rises, the high-level output signal Pe (pulse signal) is output to the outside for a predetermined time T3.

  Thereby, when the glass substrate Wg has a size within a predetermined range, a high level output signal Pe is output to the outside (when the glass substrate Wg has a size outside the predetermined range, the high level output signal Pe is output. Level output signal Pe is not output to the outside), it is possible to detect whether or not the glass substrate Wg is in a predetermined range based on the output signal Pe (a glass substrate Wg having a size outside the predetermined range). Is not detected).

  Thus, according to the present embodiment, when the pulse signals P1 and P2 are input to the output circuit 17 (output means), the determination result output from the first determination means 26A (one determination means) changes. An output signal Pe corresponding to the determination result by the second determination means 26B (other determination means) at this time is output from the output circuit 17. Therefore, it is not necessary to provide a device or the like for executing the processing separately from the photoelectric sensor, and the number of parts can be reduced.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In the above embodiment, the level (high level) of the pulse signal P2 output from the second determination unit 16B (26B) at the rising edge of the pulse signal P1 output from the first determination unit 16A (26A) Although the output circuit Pe (high level) is output from the output circuit 17, such timing is not limited to the rise of the pulse signal P1. For example, the pulse signal P1 may fall, and the output from the output circuit 17 may be performed according to the level (low level) of the pulse signal P2 at this time.

(2) In the above embodiment, the CPU 13 receives the two discriminating means 16A, 16B (26A, 26B) and the pulse signals P1, P2 from the two discriminating means 16A, 16B (26A, 26B), respectively. Although the output circuit 17 is provided, these may be configured by another CPU 13.
For example, the two determination means 16A and 16B (26A and 26B) may be provided in different CPUs. In this way, it is possible to simultaneously execute processing by the two discriminating means 16A and 16B (26A and 26B).

  (3) In the second embodiment, the size (length) of the glass substrate Wg is detected. However, the present invention is not limited to this. For example, the present invention may be applied when notch detection is performed on a translucent glass wafer or the like.

(4) Not limited to the above embodiment, for example, when the reference pulse signal P2 (its high level) is output from the second determination unit at a predetermined cycle, the pulse signal P1 output from the first determination unit The present invention can also be applied when it is necessary to detect the order of the rise timing of the pulse signal P2 and the rise timing of the pulse signal P2.
Specifically, as shown in FIG. 7, when a plurality of pulse signals P1 and P2 (high level signals for a predetermined time) are input to the output circuit 17, the first pulse P2a of the pulse signal P2 is When the first pulse P1a of the pulse signal P1 rises after rising, the output signal Pe (high level) is output from the output circuit 17, and on the contrary, the second pulse When the pulse P2b rises after P1b rises, the output signal Pe (high level) is not output from the output circuit 17. Thus, according to the present embodiment, when a plurality of pulse signals are input, the order of the pulse signals (the order of high level (or low level)) can be detected.

  (5) The above embodiment includes a light projecting unit that projects light, and a light receiving unit that receives light from the light projecting unit and outputs a light reception signal (detection signal) corresponding to the amount of light received. Although the present invention is applied to the configured photoelectric sensors 10 and 20, the present invention is not limited to this. For example, the present invention is applied to a temperature sensor or a pressure sensor, and instead of the light reception signal Si, a physical quantity detection unit (not shown; for example, a circuit that outputs a signal corresponding to temperature or pressure) A detection signal having a level corresponding to a physical state (physical quantity) may be input to the two determination units 16A and 16B.

The figure which shows the detection of the metal ball by the reflective photoelectric sensor of Embodiment 1. Block diagram showing electrical configuration of photoelectric sensor The figure which shows the change of the level of the pulse signal when the light reception signal is received The figure which shows the detection of the glass substrate by the transmission type photoelectric sensor of Embodiment 2. Block diagram showing electrical configuration of photoelectric sensor The figure which shows the change of the level of the pulse signal when the light reception signal is received The figure which shows the change of the level of the pulse signal of other embodiment. The figure which shows the structure of the conventional photoelectric sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,20 ... Photoelectric sensor 11 ... Light projection element 12 ... Light projection circuit 13 ... CPU
DESCRIPTION OF SYMBOLS 14 ... Light receiving element 15 ... Light receiving circuit 16A, 26A ... 1st discriminating means (one discriminating means)
16B, 26B ... second discrimination means (other discrimination means)
17 ... Output circuit (output means)
P1, P2 ... Pulse signal Pe ... Output signal Si ... Light reception signal T2 ... Predetermined time Wb ... Metal ball Wg ... Glass substrate Wr ... Reference glass substrate

Claims (5)

Physical quantity detection means for outputting a detection signal at a level corresponding to the physical quantity of the detection object;
A plurality of discrimination means for outputting discrimination results according to different setting conditions based on detection signals from the physical quantity detection means;
An output means for outputting an output signal corresponding to a discrimination result output from another discrimination means when a discrimination result output from one discrimination means changes among the plurality of discrimination means; Sensor. The detection sensor according to claim 1,
A light projecting means for projecting light;
A light receiving means for receiving light from the light projecting means and outputting a light reception signal corresponding to the amount of received light as the detection signal,
The plurality of determination means are configured to include two determination means, a first determination means as the one determination means and a second determination means as the other determination means,
The output means outputs an output signal based on the level of the pulse signal output as the discrimination result from the second discrimination means at the rise or fall of the pulse signal output as the discrimination result from the first discrimination means. A characteristic photoelectric sensor. The setting condition in the discrimination means is a threshold value,
Both of the two discriminating means output a low level signal when the received light signal level is equal to or higher than a threshold value, and output a high level signal when the received light signal level is equal to or lower than the threshold value. ,
The threshold values in the second determining means are first and second threshold values having a predetermined hysteresis width,
The photoelectric sensor according to claim 2, wherein the threshold value in the first determination unit is a third threshold value set between the first and second threshold values. The setting condition in the determination means is the amount of change in the level of the received light signal,
The first determining means outputs a high level signal when the amount of increase in the level of the received light signal per predetermined time is equal to or higher than a predetermined level,
The second determining means continuously outputs a high level signal for a predetermined continuous output time when the amount of decrease in the level of the received light signal per predetermined time is equal to or higher than a predetermined level.
The output means outputs a high level output signal on condition that the output signal from the first discrimination means rises when the signal from the second discrimination means is at a high level. Item 3. The photoelectric sensor according to Item 2. The photoelectric sensor according to claim 4, further comprising setting means capable of setting the continuous output time in the second determination means.

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