JP6015355B2 - Photoelectric sensor - Google Patents

Description

  The present invention relates to a photoelectric sensor, and more particularly to a photoelectric sensor of a type in which a head and an amplifier are separated.

  In general, a production line is provided with a plurality of sensors. A PLC (Programmable Logic Controller) as a control device controls a manufacturing machine in response to signals input from various sensors. For example, the photoelectric sensor compares the received light amount detected by the light receiving unit with a threshold value, and if the received light amount is larger than the threshold value, sends a signal indicating that a workpiece has been detected to the PLC.

  Japanese Patent No. 4268308 (Patent Document 1) discloses a separation type photoelectric switch (photoelectric sensor) which is one of sensors connected to a control device such as a PLC. The photoelectric switch described in Japanese Patent No. 4268308 includes a head portion and a main body portion (amplifier). By pressing a setting switch provided on the upper surface of the casing of the main body, the above-described threshold value to be compared with the amount of received light is automatically set.

Japanese Patent No. 4268308

  In a production line in which a separate photoelectric sensor is used, the head can be installed several meters away from the amplifier. Therefore, if a threshold setting switch is provided on the amplifier side, after the operator installs the head, the operator moves to the amplifier and operates the setting switch, or another operator sets the setting switch. The threshold cannot be set without operating. Therefore, workability is not good.

  The present invention has been made in view of the above-described problems, and an object thereof is to improve the installation workability of the separation type photoelectric sensor.

  The photoelectric sensor includes a head provided with a light projecting unit and a light receiving unit, and an amplifier that is connected to the head via a cable and transmits a signal according to a result of comparing the amount of received light and a threshold value to the control device. And a switch provided on the head and operated by a user. When the switch is operated, the amplifier sets a threshold value according to the amount of received light.

  Since the switch that is operated when starting the setting of the threshold value is provided in the head, the operator can cause the amplifier to set the threshold value without moving after determining the position of the head. Therefore, the installation workability of the head is improved. In particular, when the fine adjustment of the installation position of the head and the setting of the threshold value are repeated several times, the improvement in workability is large.

  An indicator lamp that is controlled to emit light when a switch that is operated to set a threshold value is operated may be provided in the head. With this indicator light, the operator can confirm whether or not the threshold value has been set.

  The threshold value may be set by any one of a plurality of methods. For example, a method of setting a threshold value that is smaller than the amount of light received when there is a workpiece (detection target), the average value of the amount of light received when there is a workpiece and the amount of light received when there is no workpiece A method of setting as a threshold value, a method of setting a range of two threshold values obtained by these two methods as a range of received light amount that can be said to be a workpiece, or the like may be used. In this case, the indicator lamp provided in the head may be controlled so that light is emitted in a different manner for each threshold setting method. Thereby, the operator can grasp | ascertain the setting method of a threshold value. The threshold setting method may be selected according to the operation mode (the number of continuous operations, the operation time, etc.) of the switch on the head side operated when setting the threshold. For example, once the switch is operated, a value smaller than the amount of received light when there is a workpiece by a predetermined value may be set as the threshold value. When the switch is operated twice continuously, an average value of the received light amount when there is a workpiece and the received light amount when there is no workpiece may be set as the threshold value. When the switch is continuously operated three times, the range of the two threshold values obtained by the two methods described above may be set as the range of the received light amount at which it can be said that there is a workpiece. The indicator lamp provided in the head unit may be controlled so as to blink at a different speed for each setting method of these threshold values.

  An indicator lamp that is controlled to emit light in a different manner depending on the amount of received light may be provided in the head. For example, the indicator lamp may be turned on when a received light amount greater than a predetermined value determined by the sensor performance is obtained. Thereby, the operator can position the head at a position where the workpiece can be reliably detected by confirming the light emission state of the indicator lamp.

  An abnormality determination circuit may be provided in the head. Thereby, the abnormality determination circuit can be omitted in the amplifier. Therefore, the amplifier can be reduced in size.

  The amplifier may be configured such that the operation on the switch on the head side for setting the threshold value can be invalidated or validated by the operation on the operation unit provided in the amplifier.

  Since the switch that is operated when starting the setting of the threshold value is provided in the head, the operator can cause the amplifier to set the threshold value without moving after determining the position of the head. Therefore, the installation workability of the head is improved.

It is a schematic perspective view which shows a photoelectric sensor. It is a figure showing a circuit configuration inside a head.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  Referring to FIG. 1, a photoelectric sensor 100 according to the present embodiment includes an amplifier (main body unit) 101, a head 102, and a cable 130 that electrically connects the amplifier 101 and the head 102. Signals are transmitted and received between the amplifier 101 and the head 102 via the cable 130.

  The amplifier 101 mainly includes a main body casing 110, an opening / closing cover 114 rotatably attached to the main body casing 110, and a frame 116 accommodated in the main body casing 110. The display unit 103 and the operation unit 104 are provided on the upper surface of the frame 116 exposed in FIG. A cable 130 is inserted into the front wall portion of the main body casing 110 located in front of the amplifier 101. An electric cord 105 in which core wires such as a power supply line and a signal line are integrated is drawn out from the back surface of the amplifier 101.

  The head 102 is provided with a light projecting unit 102a, a light receiving unit 102b, and a determination indicator lamp 102c. As an example, a light emitting diode package in which a light emitting diode chip is packaged as a light projecting element is used for the light projecting unit 102a. A PD package or the like is used for the light receiving unit 102b.

  The head 102 projects light from the light projecting unit 102 a onto the workpiece (detection target) and transmits a signal corresponding to the amount of reflected light incident from the light receiving unit 102 b to the amplifier 101 via the cable 130. To do. When the amount of received light is sufficient, the determination indicator lamp 102c is turned on.

  The amplifier 101 compares the received light amount with a threshold value, and if the received light amount is larger than the threshold value, transmits an ON signal indicating that a workpiece has been detected to a control device such as a PLC (not shown). To do. The threshold value to be compared with the amount of received light is automatically set by the user operating the operation unit 104 of the amplifier 101.

  The threshold value is set using any one of a plurality of types of methods. For example, a value smaller by a predetermined value than the amount of light received when there is a workpiece may be set as the threshold value. The average value of the amount of received light when there is a workpiece and the amount of received light when there is no workpiece may be set as the threshold value. The range of the two threshold values obtained by these two methods may be set as the range of the received light amount at which it can be said that there is a workpiece. Since a well-known technique may be used for the threshold setting method itself, detailed description thereof will not be repeated here.

  The setting of the threshold value can also be started by the user operating (specifically, pressing) a setting switch 120 provided on the head 102. Therefore, the operator can instruct the amplifier 101 to set the threshold value from the place where the head 102 is attached without having to return to the place where the amplifier 101 is located after installing the head 102 on the production line.

  The threshold setting method can be selected according to the operation mode of the setting switch 120. For example, if the operator operates the setting switch 120 once within a predetermined time, a value smaller by a predetermined value than the amount of light received when there is a workpiece is set as the threshold value. When the operator operates the setting switch 120 twice continuously within a predetermined time, the average value of the received light amount when there is a workpiece and the received light amount when there is no workpiece is set as a threshold value. When the operator operates the setting switch 120 three times continuously within a predetermined time, the two threshold ranges obtained by the two methods described above are set as the range of received light amounts that can be said to be a workpiece. .

  The threshold setting method can be confirmed from the blinking speed of the setting indicator lamp 122. That is, the setting indicator lamp 122 is controlled by the amplifier 101 so as to emit light in different modes (different blinking speeds) for each threshold setting method. When the setting of the threshold value is completed, the setting indicator lamp 122 is controlled to be lit.

  The set threshold value can be locked by operating the operation unit 104 of the amplifier 101. That is, the amplifier 101 has a function of invalidating the operation of the operation unit 104 for setting the threshold value and the operation of the setting switch 120 of the head 102.

  Further, the amplifier 101 has a function of invalidating or enabling only the operation of the setting switch 120 of the head 102 by operating the operation unit 104. That is, the threshold lock function can be set independently for the setting switch 120 of the head 102.

  In addition, the head 102 is provided with a stability indicator lamp 124. The stability indicator lamp 124 is controlled to emit light in different modes depending on the amount of received light. As an example, the stability indicator lamp 124 is controlled by the amplifier 101 so that the greater the amount of received light, the faster it blinks. When the amount of received light is larger than a predetermined value determined by the specifications of the amplifier 101 and the head 102, the stability indicator lamp 124 is controlled to be lit. By confirming the blinking and lighting state of the stability indicator lamp 124 when there is a workpiece, the operator can position the head 102 at a position where the workpiece can be reliably detected.

  With reference to FIG. 2, the circuit configuration inside the head 102 will be described. The light projecting unit 102 a includes a light projecting element (for example, a light emitting diode) 200 for projecting light, a drive circuit 202, a monitor light receiving element 204, and an abnormality determination circuit 206. The drive circuit 202 supplies drive power to the light projecting element 200 so that light is emitted with a predetermined light emission amount.

  The abnormality determination circuit 206 determines the abnormality of the head 102 based on the amount of received light detected by the monitor light receiving element 204. For example, an abnormality is detected when the amount of received light detected by the monitor light receiving element 204 exceeds a predetermined value. By providing the abnormality determination circuit 206 in the head 102 instead of the amplifier 101, the influence of noise from the outside in the cable 130 can be reduced. Therefore, the accuracy of abnormality determination can be improved.

  The light receiving unit 102 b includes a light receiving element 210 and an amplifier circuit 212. The amount of received light detected by the light receiving element 210 is transmitted to the amplifier 101 via the amplifier circuit 212.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 100 Photoelectric sensor, 101 Amplifier, 102 Head, 102a Light emitting part, 102b Light receiving part, 102c Judgment indicator lamp, 103 Display part, 104 Operation part, 105 Electric cord, 110 Main body casing, 114 Opening / closing cover, 116 frame, 120 Setting switch 122 setting indicator lamp, 124 stability indicator lamp, 130 cable, 200 light emitting element, 202 drive circuit, 204 monitor light receiving element, 206 abnormality determining circuit, 210 light receiving element, 212 amplifier circuit.

Claims (6)

A head provided with a light emitter and a light receiver;
An amplifier connected to the head via a cable and transmitting a signal according to a result of comparing the amount of received light and a threshold value to the control device;
A switch provided on the head and operated by a user;
The amplifier is a photoelectric sensor that sets the threshold according to the amount of received light when the switch is operated.   The photoelectric sensor according to claim 1, further comprising an indicator lamp provided on the head and controlled to emit light when the switch is operated. The amplifier sets the threshold value by any one of a plurality of methods,
The photoelectric sensor according to claim 2, wherein the indicator light is controlled to emit light in a different manner for each threshold value setting method.   The photoelectric sensor according to claim 1, further comprising an indicator lamp provided on the head and controlled to emit light in different modes depending on the amount of received light.   The photoelectric sensor according to claim 1, further comprising an abnormality determination circuit provided in the head.   The photoelectric sensor according to claim 1, wherein the amplifier is configured to be able to switch between invalidation and validation of an operation on the switch by an operation on an operation unit provided in the amplifier.

Images