JP2008196877A - Optical displacement sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical displacement sensor capable of connecting a sensor head to an exclusive data processing device (amplifier unit), and connecting easily even a sensor head single body from which the exclusive data processing device is separated to a versatile data processing device. <P>SOLUTION: Since the sensor head 3 is provided connectably through a versatile interface 5 not only to the exclusive data processing device (amplifier unit) 7 but also to the versatile data processing device 8, not only the sensor head 3 can be connected to the exclusive data processing device 7, but also even the sensor head 3 single body from which the exclusive data processing device 7 is separated can be connected easily to the versatile data processing device 8 by using the versatile interface 5, to thereby enable simple connection through which light receiving data or displacement data can be output from the sensor head 3 single body to the versatile data processing device 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a light projecting element that irradiates light to a measurement object and a light receiving element that receives reflected light from the measurement object of the irradiated light, and detects the amount of displacement of the measurement object. The present invention relates to a displacement sensor.

  In general, an optical displacement sensor that detects a displacement amount of a measurement object and obtains a distance to the measurement object, for example, includes a sensor head and a dedicated data processing device (amplifier unit). The sensor head has a light projecting element that irradiates light to the measurement object and a light receiving element such as an image sensor that receives reflected light from the measurement object of the irradiated light. Based on this, for example, displacement data calculated by a triangulation method is detected. The dedicated amplifier unit performs display processing such as displacement data output from the sensor head and processing such as data conversion. The amount of displacement of the measuring object M is used for measuring dimensions such as the thickness and height of the measuring object M, for example.

  As shown in FIG. 3, the triangular distance measuring method irradiates the measurement object M with the light emitted from the light projecting element 1 through the light projection lens L1, and reflects the reflected light from the measurement object M through the light receiving lens L2. Light is received by the linear image sensor 2, and the distance to the measurement object M is detected based on the light receiving spot position of the reflected light to the image sensor 2. For example, when the measurement object M approaches the sensor, the focal point moves in the direction of the pixel number 0, and when it moves away, it moves in the direction of the pixel number N. Therefore, measurement is performed based on the change in the light receiving spot position of the reflected light. The distance to the object M can be detected. FIG. 4 is a diagram illustrating an example of a received light amount distribution of reflected light incident on the linear image sensor 2. A condensing point indicating the maximum received light amount based on the received light amount distribution is a received light spot position.

Conventionally, in this optical displacement sensor, a sensor head and a dedicated amplifier unit are separately configured as a highly functional one that can perform data conversion processing and various calculations with particularly high accuracy. One connected by a signal line is known (for example, Patent Document 1).
JP 2003-14417 A

  However, since the conventional optical displacement sensor is configured to have a sensor function by combining a sensor head and a dedicated amplifier unit, the sensor head alone separated from the dedicated amplifier unit and programmable logic control (PLC) Could not connect to a general-purpose data processing device. For this reason, depending on the user, not only can the sensor head and the dedicated amplifier unit be connected to obtain high functionality, but also the light reception data or In some cases, it is desired to acquire displacement data, and it has been difficult for conventional optical displacement sensors to meet such demands.

  The present invention solves the above-described problems, enables connection of a sensor head and a dedicated data processing device (amplifier unit), and a general-purpose data processing device even with a single sensor head separated from the dedicated data processing device. An object of the present invention is to provide an optical displacement sensor that can be easily connected.

  To achieve the above object, an optical displacement sensor according to the present invention includes a light projecting element that irradiates light to a measurement object, a light receiving element that receives reflected light from the measurement object of the irradiated light, and a sensor. A sensor head having a head control means for controlling the entire head, and outputting a detected light reception data or displacement data; and a general-purpose serial connection interface for transmitting the data from the sensor head; And a dedicated data processing device, wherein the sensor head can be connected to the dedicated data processing device via the general-purpose interface, and the sensor head alone without the dedicated data processing device, Selectable sensor head that can be directly connected to a general-purpose data processing device via the general-purpose interface It is provided.

  According to this configuration, the sensor head is provided so as to be connectable to a general-purpose data processing device as well as a dedicated data processing device via the general-purpose interface. In addition, a single sensor head separated from a dedicated data processing device can be easily connected to a general-purpose data processing device using a general-purpose interface, and light reception data or displacement data is output from the sensor head to a general-purpose data processing device. Simple connection is possible.

  Preferably, the dedicated data processing device is a dedicated amplifier unit that displays at least displacement data output from the sensor head and performs data conversion processing. Therefore, in addition to the connection of the sensor head alone, complicated processing such as data conversion processing can be performed using the sensor head and the dedicated amplifier unit.

  Preferably, the sensor head is configured to change a data transmission speed when the sensor head is connected to the dedicated amplifier unit from a data transmission speed when the sensor head is connected to the general-purpose data processing device. It has. Therefore, when the sensor head and the dedicated amplifier unit are connected, the data transmission speed can be changed to a higher data transmission speed than the data transmission speed of the general-purpose data processing apparatus when the sensor head is connected alone.

  Preferably, the sensor head includes an LED that displays a communication when the sensor head alone and the general-purpose data processing device are connected, and displays a distance to the measurement object when the sensor head and the dedicated amplifier unit are connected. Display means are provided. Therefore, the operation state of the optical displacement sensor can be easily grasped.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an optical displacement sensor according to an embodiment of the present invention. As shown in FIG. 1 (A), this sensor has a light projecting element (semiconductor laser) 1 that irradiates light to a measurement object M through a light projection lens (not shown), and reflects the irradiated light from the measurement object M. A sensor head 3 that has a light receiving element 2 that receives light through a light receiving lens (not shown) and a head control means 10 that controls the entire sensor head, and outputs displacement data of the detected measurement object M; And a general-purpose serial connection interface 5 for transmitting the displacement data from the data to a dedicated data processing device 7 or a general-purpose data processing device 8. For example, the distance to the measuring object M obtained based on the displacement data (displacement amount) of the measuring object M is used for measuring the thickness and height of the measuring object M.

  The dedicated data processing device 7 includes, for example, a dedicated amplifier unit, and performs processing such as display of displacement data output from the sensor head 3 and data conversion. The general-purpose data processing device 8 includes, for example, a programmable logic control (PLC), a personal computer (PC), and an AD converter (A / D).

  In this example, displacement data is obtained by calculation of the head control means 10 based on the received light data received by the light receiving element 2 of the reflected light of the measurement object M of the light emitted from the light projecting element 1, and the displacement data is obtained. However, the received light data itself may be output instead of the displacement data. Further, although a plurality (three) of sensor heads 3 are provided, only one sensor head 3 may be provided.

  As shown in FIG. 1A, this sensor is a combination of a sensor head 3 and a dedicated amplifier unit 7, and the sensor head 3 is provided so as to be connectable to the dedicated amplifier unit 7 via a general-purpose interface 5. In addition, as shown in FIG. 1B, the sensor head 3 does not have the dedicated amplifier unit 7 and is provided so as to be directly connectable to a general-purpose data processing device 8. That is, the connection between the sensor head 3 and the dedicated amplifier unit 7 and the connection between the sensor head 3 alone and the general-purpose data processing device 8 that are the use of the sensor head 3 alone are selectable. In FIG. 1A, a general-purpose data processing device 8 is connected to the dedicated amplifier unit 7, but the general-purpose data processing device 8 may be omitted as necessary.

  For example, a semiconductor laser diode (LD) driven by a laser drive circuit 4 is used for the light projecting element 1 in FIG. Examples of the light receiving element 2 include a linear image sensor and a PSD (position detection element). In this example, a linear image sensor is used. As the linear image sensor 2, a CCD type image sensor that sequentially outputs signal charges accumulated in a plurality of pixels to a shift register and then sequentially outputs them, or sequentially transmits and outputs signal charges accumulated in a plurality of pixels. A type of image sensor or the like is used.

  For the general-purpose interface 5, general-purpose serial connection RS422, RS485, RS232C, or the like is used. In this example, the RS 422 transmits received light data between the RS 422 transceiver 5a of the sensor head 3 and the RS 422 transceiver 5b of the dedicated amplifier unit 7 via a general-purpose cable 9 such as a twisted pair structure communication cable. This twisted pair structure communication cable can reduce the noise by canceling out the magnetic flux by combining the two cables together, so that the reduction in data transmission speed due to noise during high-speed transmission can be reduced.

  The general-purpose cable 9 exiting from the sensor head 3 is only one system, and the sensor head 3 and the dedicated amplifier unit 7 are connected as described above, and the sensor head 3 and the general-purpose data processing device 8 are connected to the sensor head 3. The RS422 transceiver 5a is connected to an interface input unit provided in the general-purpose data processing device 8 through the general-purpose cable 9.

  The dedicated amplifier unit 7 is provided so as to be compatible with all data transmission speeds (baud rates) from the low speed to the high speed that can be set by the sensor head 3. The data processing device 8 does not necessarily correspond to all data transmission speeds that can be set by the sensor head 3.

  1A changes the data transmission speed when the sensor head 3 and the dedicated amplifier unit 7 are connected from the data transmission speed when the sensor head 3 and the general-purpose data processing device 8 are connected. Transmission rate changing means 12 is provided. The transmission speed changing circuit 12 includes a connection detection unit that detects that the sensor head 3 and the dedicated amplifier unit 7 are connected via the general-purpose interface 5, and data transmission of the general-purpose data processing device 8 based on the connection detection. And a baud rate conversion unit for automatically converting to a data transmission rate (baud rate) higher than the speed. This change in data transmission speed is performed based on command transmission from the amplifier control means 20 to each sensor head 3 via the general-purpose cable 9 based on detection of connection of the general-purpose cable 9 to the RS transceiver 5b of the dedicated amplifier unit 7. Is called.

  In this case, for example, the data transmission speed when the sensor head 3 separated from the dedicated amplifier unit 7 is connected is automatically set to a low speed (9600 bps or the like) compatible with all general-purpose data processing devices 8, for example. When the sensor head 3 and the dedicated amplifier unit 7 are connected, the sensor head 3 is automatically converted to the highest data transmission rate that can be set, for example. The dedicated amplifier unit 7 can be set to other data transmission speeds by a user interface 26 described later depending on the surrounding noise conditions, communication cables, and the like. It is possible to reset to an arbitrary data transmission rate according to conditions such as the communication specifications of the device.

  As a result, the data transmission speed when connecting the sensor head 3 alone can be automatically set so as to be compatible with the general-purpose data processing device 8, and when the sensor head 3 and the dedicated amplifier unit 7 are connected, Can be automatically changed to a data transmission rate higher than the data transmission rate of the general-purpose data processing device 8 in FIG.

  The sensor head 3 displays a communication means when the sensor head 3 is connected alone, and a display means (LED) that displays a distance to the measurement object M when the sensor head 3 and the dedicated amplifier unit 7 are connected. Display section) 13. For example, the red (R), green (G), and blue (B) LEDs indicate how much data is being transmitted in the communication display, and the distance display indicates the far, medium, and near distance display. Do. Therefore, the operation state of this sensor can be easily grasped.

  As shown in FIG. 2, the head control means (head control circuit) 3 further includes a received light amount distribution acquisition means 15, a measurement value averaging means 16, a sensitivity adjustment means (shutter control means) 17, and a threshold value adjustment means 18. . The received light amount distribution acquisition unit 15 acquires received light amount distribution data of each pixel of the linear image sensor 2. In addition to the distance measurement data, the received light amount distribution data is used for confirming the light receiving state at the location where the sensor is installed and for changing the threshold value of the threshold adjusting means 18. The measurement value averaging unit 16 averages the received light data by performing, for example, a calculation using a moving average method. By this averaging, desired resolution, response speed, and the like can be obtained.

  The head control means 3 performs sampling control for controlling the time for reading out the accumulated charges of all the pixels of the linear image sensor 2 in order to obtain the received light data. The sensitivity adjustment means 17 performs the light reflectance of the measuring object M. The sensitivity is adjusted by performing control to automatically adjust the opening degree of the shutter with respect to the linear image sensor 2 in accordance with the size of. Thus, since the shutter control for the linear image sensor 2 is performed according to the light reflectance of the measurement object M, the shutter opening time is kept constant while keeping the sampling period constant with respect to the change in the type of the measurement object M. By changing the above, it is possible to obtain a constant light reception level regardless of the type of the measurement object M, while making the sampling cycle constant as well as the light projection power and the light projection time.

  The threshold adjusting means 18 adjusts the threshold based on the magnitude of the received light amount of the linear image sensor 2 and a peak position determining unit that determines the peak position of the received light level distribution of the linear image sensor 2 based on the received light level threshold. And a threshold value setting unit to be set. In the threshold setting unit, based on the magnitude of the received light amount of the linear image sensor 2, for example, based on the sum of the received light amount of each pixel of the linear image sensor 2 obtained from the received light amount distribution acquisition means 15, Is adjusted and set, the peak position determination unit determines the peak position of the light reception level distribution of the linear image sensor 2 based on the set threshold value. For example, the peak position determination unit determines an intermediate position between two coordinates equal to the threshold value in the light reception level distribution as the peak position, as in the conventional case. Even if the light reception level distribution is asymmetrical with respect to the peak position, if only the distribution portion on the head side with a relatively high specific light reception level or higher is extracted, the waveform is almost symmetrical with respect to the peak position. Become. Thus, the extracted peak position is close to the actual peak position, and the distance can be accurately measured based on this.

  Since the dedicated amplifier unit 7 in FIG. 1A performs complicated processing such as display of displacement data output from the sensor head 3 and data conversion and various calculations, the sensor head 3 and the dedicated amplifier unit 7 are combined. A highly functional sensor can be realized.

  In the dedicated amplifier unit 7 of FIG. 1A, when connected to a programmable logic control (PLC) as a general-purpose data processing device 8, a control input / output unit 21 is connected and connected to a personal computer (PC) or the like. Interface (RS232C, USB) 22 such as a personal computer (PC) is connected, and an analog interface 23 is connected when connected to an AD converter (A / D). In addition, a user interface 26 for user connection is provided.

  The amplifier control means (amplifier control circuit) 20 controls the entire dedicated amplifier unit 7, and generates commands that cause the sensor head 3 to perform each control. Each of the generated commands is transmitted to the head control means (head control circuit) 10 to switch the output of the displacement data or light reception data, change the data transmission speed, and process the above-described means 15 to 18. Control in the sensor head 3 including is performed.

  Thus, since the sensor head 3 is controlled based on the command from the dedicated amplifier unit 7, the sensor head 3 is not provided with a changeover switch. If the changeover switch is provided, the sensor head 3 is opened from the opening. Since there is no fear of water intrusion or the like in 3, it has a waterproof effect.

  In FIG. 1B, the sensor head 3 is directly connected to a general-purpose data processing device 8 such as PLC or PC without connecting the dedicated amplifier unit 7 via the general-purpose interface 5. is there. Other configurations of the sensor head 3 are the same as those in FIG.

  The RS422 transceiver 5a of the sensor head 3 and the general-purpose data processing device 8 are connected to each interface input unit via a general-purpose cable 9. In the general-purpose data processing device 8, for example, in the PLC, an interface input terminal block is provided and can be connected to the general-purpose cable 9. Further, for example, in the case where the PC is provided with another RS232C connector instead of the RS422 connector, the connection is made by using conversion connection means between the general-purpose interfaces such as the RS422-RS232C conversion connection connector. Thus, the general-purpose interface 5 can be commonly connected when the sensor head 3 is connected alone and when the sensor head 3 and the dedicated amplifier unit 7 are connected.

  In the connection of the sensor head 3 alone in FIG. 1B, not in the amplifier control means 20 of the dedicated amplifier unit 7 shown in FIG. 1A but in a general-purpose data processing device 8 such as a PLC or a PC. The command is generated in advance and sent to the head control means (head control circuit) 10. Thus, displacement data or light reception data can be easily obtained on the user side simply by replacing the connection of the general-purpose cable 9 from the dedicated amplifier unit 7 to a general-purpose data processing device 8 such as PLC or PC.

  Thus, in the present invention, the sensor head 3 is provided so that it can be connected not only to the dedicated data processing device (amplifier unit) 7 but also to the general-purpose data processing device 8 via the general-purpose interface 5. In addition to the connection between the sensor head 3 and the dedicated data processing device 7, the sensor head 3 alone separated from the dedicated data processing device 7 can be easily connected to the general-purpose data processing device 8 using the general-purpose interface 5. A simple connection of outputting light reception data or displacement data from the head 3 alone to the general-purpose data processing device 8 is possible.

  Thereby, since a user who does not need a high function such as acquisition of displacement data or light reception data connects only the sensor head 3 alone, an inexpensive system using the general-purpose data processing device 8 can be constructed. Further, when high functions such as data conversion processing and various arithmetic processing are required, it can be realized by combining the sensor head 3 and the dedicated amplifier unit 7.

  In this embodiment, the connection between the sensor head 3 and the dedicated amplifier unit 7 and the connection between the sensor head 3 alone and the general-purpose data processing device 8 are selectable. Only the processing device 8 may be connected.

(A), (B) is a block block diagram which shows the optical displacement sensor which concerns on one Embodiment of this invention. It is a block block diagram which shows the head control means of the same optical displacement sensor. It is a side view which shows a triangulation system. It is a figure which shows an example of received light amount distribution.

Explanation of symbols

1: Projection element (LD)
2: Light receiving element (linear image sensor)
3: Sensor head 5: General-purpose interface (RS422, etc.)
7: Dedicated data processing device (amplifier unit)
8: General-purpose data processing device (PLC, etc.)
9: General-purpose cable 10: Head control means (head control circuit)
12: Transmission speed changing circuit 13: Display means (display unit)
15: received light amount distribution acquisition means 16: measurement value averaging means 17: sensitivity adjustment means 18: threshold value adjustment means 20: amplifier control means (amplifier control circuit)
M: Measurement object

Claims (4)

Light receiving data detected by a light projecting element that irradiates light to the measurement object, a light receiving element that receives reflected light from the measurement object of the irradiated light, and a head control means that controls the entire sensor head Or a sensor head that outputs displacement data;
A general-purpose serial connection interface for transmitting the data from the sensor head,
Composed of a combination of the sensor head and a dedicated data processing device, the sensor head being connectable to the dedicated data processing device via the general-purpose interface, and the sensor head alone having no dedicated data processing device The optical displacement sensor is provided so that the sensor head can be directly connected to a general-purpose data processing device via the general-purpose interface. In claim 1,
An optical displacement sensor, wherein the dedicated data processing device is a dedicated amplifier unit that performs display and data conversion processing of displacement data output from at least the sensor head. In claim 2,
The sensor head includes transmission speed changing means for changing the data transmission speed when the sensor head and the dedicated amplifier unit are connected from the data transmission speed when the sensor head is connected to the general-purpose data processing device. Optical displacement sensor. In claim 2,
The sensor head includes a display means including an LED for performing communication display when the sensor head alone and the general-purpose data processing device are connected, and for displaying a distance to the measurement object when the sensor head and the dedicated amplifier unit are connected. An optical displacement sensor provided.

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