Optical displacement sensor

Abstract

To provide an optical displacement sensor which can further downsize a housing constituting a head part.SOLUTION: A relay cable 6 extending from a head part 2 is integrated with a body part 4. The head part 2 mainly has a function of projecting light to a detection target or receiving light from the detection target. The body part 4, on the other hand, includes a power source circuit 30, a display unit 12, and an operation unit 402. The head part 2 includes a green laser light source 520, and emits green laser light and forms a spot in a surface of the detection target.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to an optical displacement sensor.

Background Art

[0002] Patent Documents 1 and 2 disclose optical displacement sensors. An optical displacement sensor is used to project light onto a detection area, receive the reflected light with a light receiving element, and detect a detection target based on the output of the light receiving element.

[0003] Displacement sensors are known to be of an integrated type and a separable type. In the integrated type, in addition to the light projecting and receiving section, a display section and an operation section are provided in a single housing. The separable type is composed of a head section that includes a power supply circuit and projects and receives light, and a controller (separate amplifier) that controls this head section. The separate amplifier is provided with a display section and an operation section, and this separate amplifier is fixed to a DIN rail.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the integrated displacement sensor is provided with a display section and an operation section, it is large-sized, and there are problems such as the display section not being visible and the operation section not being operable when installed in a narrow space, so the installation location is limited.

[0006] The separable displacement sensor requires a wiring error protection circuit to protect the sensor from a pairing failure between the head section and the separate amplifier, and there is a problem that the circuit configuration of the head section becomes complicated.

[0007] An object of the present invention is to provide an optical displacement sensor capable of further reducing the size of a housing constituting a head portion.

Means for Solving the Problems

[0008] According to the present invention, the above technical problem is solved by a first housing having a transmission window for transmitting light, A cable for transmitting power to the first housing, Front a second housing that is connected to the first housing via the cable and has at least a first power supply circuit for supplying power of a first voltage to the first housing via the cable and is integrated with the cable. Eh, The first housing includes: A semiconductor laser light source that projects measurement light toward a detection region through the transmission window; A second power supply circuit that steps down the voltage received from the first power supply circuit; An imaging element that is driven by the power supplied from the second power supply circuit, and photoelectrically converts the measurement light from the detection region through the transmission window to generate a light reception signal; A measurement unit that measures the displacement of a detection target based on the light reception signal generated by the imaging element; The semiconductor laser light source driven by the power supplied from the first power supply circuit is driven at a higher voltage than the imaging element. This is achieved by providing an optical displacement sensor characterized by the above.

[0009] According to the present invention, Since the power of the first voltage supplied to the semiconductor laser light source of the first housing is housed in the second housing, the first housing can be miniaturized.

[0010] The effects and other objects of the present invention will become apparent from the following detailed description of the preferred embodiments.

Brief Description of the Drawings

[0011]

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Modes for Carrying Out the Invention

Examples

[0012] <First Embodiment (Figs. 1 to 26)> FIG. 1 shows the displacement sensor of the first embodiment. Specifically, the displacement sensor of the first embodiment is an optical triangulation sensor 100. The triangulation sensor 100 is divided into a head portion 2 constituting a first housing and a main body portion 4 constituting a second housing, and a relay cable 6 extending from the head portion 2 is integrated with the main body portion 4. The head portion 2 is mainly configured to perform light transmission and reception toward a detection target, while the main body portion 4 is composed of a power supply circuit, a display portion, and an operation portion. The head portion 2 includes a green laser light source, and emits this green laser light to form a spot on the surface of the detection target.

[0013] According to the triangulation sensor 100 of the first embodiment, since the head portion 2 is limited to the function of performing light transmission and reception toward a detection target without a display function, it can be miniaturized. Therefore, there is a degree of freedom in selecting the location where the head portion 2 is installed. Also, the main body portion 4 integrated by the relay cable 6 also has a degree of freedom in selecting the installation location. From this, by installing the head portion 2 at a location suitable for measuring the detection target and installing the main body portion 4 at an arbitrary location near the head portion 2, while visually recognizing the spot of the green laser light appearing on the surface of the detection target to confirm whether the position of the spot is appropriate and while confirming the display on the display portion of the main body portion 4, setting operations such as determining a threshold value can be performed.

[0014] Power is supplied from the main body 4 to the head unit 2, and signals are exchanged between the main body unit 4 and the head unit 2. The relay cable 6 may be connected to the head unit 2 and / or the main body unit 4 with a connector interposed therebetween, but by connecting it without a connector, the I / O port becomes unnecessary. When a connector is interposed, by preparing a plurality of relay cables 6 with different lengths, the separation distance between the head unit 2 and the main body unit 4 can be freely set, but a connection part including an I / O port is required. By connecting without a connector, not only can the connection parts of the head unit and the main body unit 4 to the relay cable 6 be miniaturized, but also measures such as a protection circuit regarding miswiring etc. between the head unit and the main body unit 4 paired with this become unnecessary. Also, the problem of mismatch such as accidentally connecting to other models does not occur.

[0015] Among the components included in a general triangulation distance measurement sensor, a group of components such as optical components required for triangulation distance measurement, elements related thereto, and a power supply board are housed in the head unit 2, and other dot matrix displays, for example, components such as an organic EL display (OELD) and operation buttons are provided in the main body unit 4. Thereby, the head unit 2 can be miniaturized.

[0016] FIG. 2 shows the main body unit 4. The main body unit 4 has an elongated outer shape with a somewhat flat substantially rectangular cross section, and has a head side end 4a located at one end in the longitudinal direction and an output side end 4b located at the other end in the longitudinal direction. Further, the side surfaces composed of the four surfaces of the main body unit 4 include a relatively wide first side surface 4c and a narrow second side surface 4d adjacent to the first side surface 4c. The main body unit 4 employs a waterproof structure including connection parts for the relay cable 6 and the output cable 8. The relay cable 6 and the output cable 8 may be cables provided with a metal jacket, or may be cables without a metal jacket. It is preferable to configure the relay cable 6 and the output cable 8 with cables provided with a metal jacket to enhance robustness.

[0017] An output cable 8 is connected to the main body 4, and a determination signal, that is, an ON / OFF signal, is output from the main body 4 through the output cable 8 to an external environmental device 10 (Fig. 1) such as a PLC, a controller of a discrete sensor, and a control device. Both the relay cable 6 and the output cable 8 have bendable flexibility. As shown in Fig. 1, the relay cable 6 is folded back and bundled, and this state is maintained by the binding band B, so that the distance between the head portion 2 and the main body portion 4 can be adjusted arbitrarily. Referring to Fig. 2, the main body 4 has a groove-shaped neck portion N extending in the circumferential direction protruding longitudinally from the head-side end 4a and the output-side end 4b, respectively. The circumferential surface of the neck portion N is preferably circular. By passing the binding band B over the neck portion N, it can be fixed at an arbitrary installation location IL close to the head portion 2, for example, about 30 cm away, for example, fixed to a pipe. Also, as shown in Fig. 3, for example, it can be fixed to a group of cables Cb using the binding band B. In the example shown in Fig. 3, the binding band B is passed over the relay cable 6 and the output cable 8 to fix the main body 4 to the group of cables Cb, but the binding band B may also be passed over the neck portion N.

[0018] As a modification regarding the arrangement position of the neck portion N, instead of the neck portion N, grooves for receiving the binding band B may be provided in the main body 4 near the head-side end 4a and the output-side end 4b. An OELD 12 is disposed on the wide first side surface 4c. Also, on this first side surface 4c, a main body operation indicator lamp 14 is disposed on one end side with the OELD 12 interposed therebetween, and a SET button 16 is disposed on the other end side. The main body operation indicator lamp 14 lights or blinks synchronously in the same color as the front operation indicator lamp 70 and the output unit operation indicator lamp 76 of the head portion 2 to be described later.

[0019] The main body operation indicator light 14 includes a green LED. This green is common in that it is the same as the green of the laser light, and green has excellent relative visibility. The SET button 16 is used to select an operation mode such as automatic setting of a threshold value (teaching mode). On the narrow second side surface 4d, an UP button 18, a DOWN button 20, and a mode button 22 are arranged adjacent to each other. The UP / DOWN buttons 18, 20 are used, for example, to adjust a threshold value or select a menu. The mode button 22 is used to switch the operation mode of the triangulation sensor 100. The above-described SET button 16 may be arranged on the narrow second side surface 4d instead of the first side surface 4c.

[0020] The second side surface 4d where the UP button 18, the DOWN button 20, and the mode button 22 are arranged is protected at both longitudinal ends by raised portions Sm (FIG. 2). That is, the second side surface 4d is configured as a basin surrounded by two raised portions Sm. The top surfaces of the UP button 18, the DOWN button 20, and the mode button 22 are lower than the raised portions Sm. Thus, even if some object collides, this object is blocked by the raised portions Sm, preventing an incorrect operation in which the UP button 18, the DOWN button 20, and the mode button 22 are accidentally pressed down.

[0021] Regarding the above-described main body operation indicator light 14, either one of the two raised portions Sm may be replaced with the operation indicator light. Also, the two raised portions Sm may be omitted, and an operation indicator light may be provided at the site where one of the raised portions Sm is located. As described above, the raised portion Sm has a function of preventing an incorrect operation in which the UP button 18, the DOWN button 20, and the mode button 22 are accidentally pressed down. Instead of the raised portion Sm, a key lock function for preventing an incorrect operation of the operation buttons including the UP button 18, the DOWN button 20, and the mode button 22 may be provided. This key lock mechanism is not limited to a physical mechanism and can be implemented by software. For example, while the sensor 100 is performing a predetermined operation, an incorrect operation can be prevented by not accepting an operation of the operation buttons.

[0022] FIG. 4 is a diagram for explaining the elements disposed inside the head unit 2. As described above, the head unit 2 is configured to be limited to the optical components required for triangulation distance measurement, the elements related thereto, and the minimum necessary power supply board for driving these. That is, the head unit 2 is designed with the intention of ultimate miniaturization. By miniaturization, the degree of freedom in selecting the installation location of the head unit 2 can be increased. And since the main body unit 4 integrally connected to the head unit 2 by the cable 6 can be fixed at an arbitrary location using the binding band B, for the user, by installing the main body unit 4 at a convenient location relatively close to the head unit 2, when setting the determination threshold value, etc., the display of the OELD 12 of the main body unit 4 can be confirmed while operating the UP button 18, DOWN button 20, etc. of the OELD 12.

[0023] The measurement light emitted from the head unit 2 is the green laser light described later. Compared with the red laser light, the green laser light with a shorter wavelength has a clear contour of the spot image and the spot image is narrowed and small, so the accuracy of the triangulation distance measurement sensor 100 can be improved. Green is known to be excellent in relative sensitivity as described above. Even if the power of the green laser light is limited to achieve safety standards Class 1, 2, the visibility of the spot of the green laser light can be maintained. As described above, the main body unit 4 can be installed at an arbitrary location near the head unit 2. As described above, by miniaturizing the head unit 2, the degree of freedom in selecting the installation location can be increased. Therefore, by installing the head unit 2 at a location suitable for measuring the detection target and installing the main body unit 4 at an arbitrary location near the head unit 2, while visually recognizing the spot of the green laser light appearing on the surface of the detection target to confirm whether the position of the spot is appropriate and while confirming the display of the OELD 12, setting operations such as the determination threshold value can be performed.

[0024] A green laser light source generally requires a higher voltage compared to a red laser light source. A power supply circuit 30A (Fig. 12) for the green laser light source that generates a voltage suitable for the green laser light source is provided in the main body 4, and a power supply circuit 78 that generates a voltage suitable for other electronic components (e.g., imaging element 60, light receiving circuit 62) is provided in the head unit 2. Since the power supply circuit 30A for the green laser light source is moved out of the head unit 2 and this power supply circuit 30A for the green laser light source is provided in the main body 4, the head unit 2 can be miniaturized. Also, in order to further increase the degree of freedom in installing the head unit 2, while miniaturizing the head unit 2, a housing structure is adopted in which surfaces other than the light transmitting / receiving surface 2a and the corner 2e where the cable 6 is located of the head unit 2 are flat surfaces, so that the head unit 2 can be installed using its side surface, rear surface 2d, etc. In other words, by adopting a configuration in which the head unit 2 does not have surfaces that constitute a user interface other than the light transmitting / receiving surface 2a and the corner 2e, the degree of freedom regarding the installation of the head unit 2 can be increased.

[0025] The head unit 2 includes a motion sensor 50 for detecting a change in the installation posture of the head unit 2. A typical example of the motion sensor 50 is a gyro sensor, and other examples include an acceleration sensor and a geomagnetic sensor. The motion sensor 50 is installed integrally with the head unit 2. Specifically, the motion sensor 50 is assembled to the head unit 2 so as not to undergo relative displacement with respect to the head unit 2. Thereby, when the head unit 2 receives an external force and the installation posture of the head unit 2 changes, resulting in an optical axis displacement, the motion sensor 50 can sensitively detect this, and thereby an optical axis displacement occurrence alarm can be notified.

[0026] The head unit 2 includes a light projecting unit 52, a light projecting lens 54, a light receiving lens 56, a mirror 58, and an imaging device 60, and an optical path for triangulation is formed by these elements. The light projecting lens 54 is composed of a collimator lens. As a modified example, the light projecting lens 54 may be configured by a combination of a collimator lens and a cylindrical lens. The combination of a collimator lens and a cylindrical lens has the advantage of improving accuracy. The imaging device 60 is composed of a CMOS linear image sensor, and the imaging device 60 includes a charge storage element. The imaging device 60 and the light receiving circuit 62 constitute a light receiving unit 64.

[0027] The light projecting unit 52 is composed of a semiconductor laser light source (InGaN / GaN gallium nitride system) that emits green laser light. The head unit 2 projects green laser light toward the detection region of the detection target. The state of the spot on the workpiece surface affects the detection accuracy. The smaller the focused spot, the better the detection accuracy. The green laser light has a better spot state than red laser light. As is known, green is excellent in relative visibility. Utilizing this characteristic, the visibility of the spot can be ensured even when the intensity and power of the green laser light are limited. It is desirable for the user to be able to visually confirm with the naked eye that the projection beam is irradiated at the desired position on the workpiece, which is important for proper execution of optical axis adjustment, threshold setting, and ultimately detection.

[0028] The green laser light emitted from the light projecting unit 52 reaches the workpiece through the light projecting lens 54 and the light projecting window 66. The reflected light reflected from the surface of the workpiece passes through the light receiving window 67 and the light receiving lens 56, is refracted by the mirror 58, and is received by the light receiving unit 64. That is, the light receiving unit 64 receives the green laser light reflected from the detection region of the workpiece, and photoelectrically converts it to generate a light receiving signal. The light projecting unit 52 and the light receiving unit 64 are controlled by a processor 68 built into the head unit 2.

[0029] As can be seen from FIG. 4, the head unit 2 has a relatively thin substantially rectangular parallelepiped shape, and the above-described light projection window 66 and light reception window 67 are arranged on the narrow light projection / reception surface 2a. Also, between the light projection window 66 and the light reception window 67, a front operation indicator lamp 70 composed of, for example, two-color LEDs of red and green is disposed. The front operation indicator lamp 70 can be lit or blinked in red, green, or yellow which is a mixed color of red and green.

[0030] As can be seen from FIGS. 1 and 4, the head unit 2 has a substantially rectangular parallelepiped shape, and only the light projection / reception surface 2a constitutes the user interface. With this configuration, the head unit 2 can be miniaturized. And a configuration is adopted in which the front operation indicator lamp 70 is arranged on the light projection / reception surface 2a which is the only user interface. Each surface except for the inclined corner 2e where the light projection / reception surface 2a and the relay cable 6 are located is composed of a flat surface. Regarding the installation of the head unit 2, the head unit 2 can be installed using any surface except for the light projection / reception surface 2a and the corner 2e. An operation unit may be provided on the light projection / reception surface 2a which constitutes the user interface together with the front operation indicator lamp 70 or on the front operation indicator lamp 70, or a display unit may be provided.

[0031] Of the first and second ends 2b and 2c in the longitudinal direction of the head unit 2, the corner 2e between the second end 2c away from the light projection window 66 and the back surface 2d facing the light projection / reception surface 2a has a cutout shape, and this corner 2e is preferably composed of a 45° inclined surface. A hole through which the relay cable 6 passes is formed in this corner 2e, and the hole is blocked from water intrusion by a waterproof packing 72. Adjacent directly to the waterproof packing 72, two-color LEDs 74 of the same color as the front operation indicator lamp 70 are arranged inside the head unit 2. The waterproof packing 72 is composed of a light-transmitting light guide member, and together with the LED 74 and the light guide waterproof packing 72, a second operation indicator lamp 76 is constituted. The front operation indicator lamp 70 and the output unit operation indicator lamp 76 are lit in yellow or green in synchronization with the ON / OFF determination signal, and are error-displayed, for example, by blinking in red. The lighting colors of the front operation indicator lamp 70, the output unit operation indicator lamp 76, and the operation indicator lamp 14 of the main body unit 2, that is, green, are common in that they are the same as the green of the laser light, and green has excellent relative visibility.

[0032] FIG. 5 is a cross-sectional view of the head portion 2. An LED substrate 92 is disposed at the corner portion 2e, and red and green LEDs 74 are mounted on the LED substrate 92. The light guide material of the waterproof packing 72 having a water stop function related to the relay cable 6 is preferably a milky white fluororubber, vinyl acetate rubber, or silicon rubber. The light emitted by the red and green LEDs 74 causes the light guide waterproof packing 72 to emit light while being diffused by the light guide waterproof packing 72.

[0033] In the operation of the triangulation sensor 100, the head portion 2 is installed with the light projecting / receiving surface 2a and the corner portion 2e where the relay cable 6 is located exposed. Therefore, not only the front operation indicator lamp 70 located on the light projecting / receiving surface 2a but also the lighting and blinking of the output portion operation indicator lamp 76 located at the corner portion 2e where the relay cable 6 is located are not blocked.

[0034] The relay cable 6 extends from the corner portion 2e formed by the inclined surface. Therefore, regarding the installation of the head portion 2, the head portion 2 can be installed using any one of the five surfaces, namely, the two wide side surfaces, the rear surface 2d, and the first and second ends 2b and 2c of the head portion 2.

[0035] By folding back and bundling the relay cable 6, the distance between the head portion 2 and the main body portion 4 can be arbitrarily adjusted (FIG. 1), and the location where the main body portion 4 is installed and fixed is also arbitrary (FIGS. 2 and 3). Regarding the installation of the main body portion 4, a location close to the head portion 2 is selected, and the main body portion 4 is positioned in a posture where the user can easily check the OELD 12. Since the main body operation indicator lamp 14 is arranged on the same surface as the OELD 12, the user can easily visually recognize the main body operation indicator lamp 14.

[0036] In the operation of the triangulation sensor 100, the total of three operation indicator lights, namely the front operation indicator light 70 and the output unit operation indicator light 76 of the head unit 2 and the operation indicator light 14 of the main body unit 4, are located in positions that are easily noticeable even when the user does not move. From this, the user can confirm the operation of the triangulation sensor 100 by any one of the front operation indicator light 70 and the output unit operation indicator light 76 of the head unit 2 and the operation indicator light 14 of the main body unit 4.

[0037] As described above with reference to FIG. 2, by passing the binding band B around the groove-shaped neck portion N of the main body unit 4, the main body unit 4 can be fixed at an arbitrary location IL close to the head unit 2. The main body unit 4 has a rectangular cross-sectional shape. The first side surface on which the OELD 12 is installed and the narrow second side surface on which the UP / DOWN buttons 18, 20, etc. are installed intersect at right angles to each other. The third side surface opposite to the first side surface and the fourth side surface opposite to the second side surface are composed of flat surfaces, and these third side surface and fourth side surface constitute the installation surface. In a state where the third side surface and / or the fourth side surface is in contact with the installation location, it can be fixed to an arbitrary relatively flat location IL (for example, a pillar) in the vicinity of the head unit 2 using the above-mentioned binding band B.

[0038] FIG. 6A and FIG. 6B are block diagrams for explaining the control system of the head unit 2. Referring to FIG. 6A, the green laser light (wavelength: 500 nm to 555 nm, preferably 500 nm to 532 nm) emitted by the green laser diode (LD) 520 constituting the light projecting unit 52 is monitored by a photodiode (monitor PD) 522, and the output current of this monitor PD 522 is fed back to the light projecting control unit 680 (FIG. 6B) via the I / V conversion circuit 524 and the A / D conversion circuit 526. The green LD 520 is controlled by the LD drive circuit 530 (FIG. 6A), and this LD drive circuit 530 is controlled by the light projecting control unit 680 (FIG. 6B). Referring to FIG. 6A, the LD drive circuit 530 includes a current control circuit 532 and a light projecting switch circuit 534. A control signal is input from the light projecting control unit 680 (FIG. 6B) to the current control circuit 532 (FIG. 6A) via the D / A conversion circuit 536, and a control signal is also input from the light projecting control unit 680 (FIG. 6B) to the light projecting switch circuit 534. Thereby, the green LD 520 projects laser light at a predetermined period and with a predetermined power.

[0039] Referring to FIG. 6A, the current flowing through the LD drive circuit 530 is monitored by an overcurrent detection circuit 538. The overcurrent detection circuit 538 includes a current detection circuit 1002 and a comparison unit 1004. When the current flowing through the LD drive circuit 530 is greater than a preset predetermined value, an overcurrent detection signal is supplied from the comparison unit 1004 to the light projecting control unit 680 (FIG. 6B). Specifically, the current flowing through the green LD 520 is converted into a voltage and compared with a reference voltage for overcurrent detection, and the comparison unit 1004 determines whether the voltage based on the current flowing through the green LD 520 is within the reference voltage for overcurrent detection. When an overcurrent is detected, the light projecting control unit 680 (FIG. 6B) executes control to stop the light projection or suppress the overcurrent.

[0040] Based on the light reception signal from the imaging element 60 (Fig. 6A), the position of the image of the light projection spot in the imaging element 60 is specified, and the displacement of the workpiece is measured based on the specified position of the light projection spot. The light reception circuit 62 constituting the light reception unit 64 (Fig. 6A) is composed of a CMOS control circuit 1010, an amplifier circuit 1012, and a low-pass filter 1014, and the light reception signal output from the imaging element 60 is amplified by the amplifier circuit 1012. The light reception information output by the light reception unit 64 is input to the processor 68 (Fig. 6B) via the A / D conversion circuit 640. The processor 68 includes a peak light reception amount detection unit 682, a peak position detection unit 684, a distance calculation unit 686, a distance determination unit 688, and an output unit 690. The peak light reception amount detection unit 682 detects the peak value of the light reception amount, and this peak value is input to the light projection control unit 680 and reflected in the light projection control. Based on the light reception information generated by the light reception unit 64 (Fig. 6A), the peak position of the light reception amount is measured by the peak position detection unit 684 (Fig. 6B). That is, the peak position detection unit 684 measures the peak position of the light reception amount based on the light reception information, and this peak position information is supplied to the distance calculation unit 686. The distance calculation unit 686 calculates the distance to the workpiece with reference to a table 692 showing the correspondence between the peak position and the distance. The distance to the workpiece obtained by the distance calculation unit 686 is supplied to the distance determination unit 688, and the distance determination unit 688 makes a determination by comparing it with the determination threshold value 694 stored in the memory. The determination signal binarized to ON / OFF is supplied to the main body unit 4 through the output unit 690 and the communication unit 80. As will be described later, in the main body unit 4, a logical ON / OFF determination signal is generated based on the output logic set by the user, and this logical ON / OFF determination signal is output from the main body unit 4 to the outside. As a modification, the determination signal generated by the head unit 2 may be generated by the main body unit 2. Also, the distance to the workpiece obtained by the distance calculation unit 686 is supplied to the main body unit 4 through the output unit 690 and the communication unit 80.

[0041] The light reception information output by the light reception unit 64 is used for controlling the exposure period of the imaging element 60 and the control of the light projection pulse width, and thereby it is controlled to project a laser light power that meets the safety standard class 1 or 2 set by the user. Referring to FIG. 6B, the light reception information output by the light reception unit 64 is input to the peak light reception amount detection unit 682, and the peak light reception amount is detected by the peak light reception amount detection unit 682. This actual peak light reception amount is input to the comparison unit 1020. In the comparison unit 1020, the actual peak light reception amount is compared with a predetermined target area 1032 in the height direction of the peak light reception amount stored in the memory. Based on this comparison, the exposure period adjustment unit 1024 adjusts the exposure period, and this information is supplied to the exposure signal generation unit 1026. The exposure signal generation unit 1026 generates exposure period information and supplies it to the CMOS control circuit 1010 (FIG. 6A). The CMOS control circuit 1010 drives the imaging element 60 based on the exposure period determined by the exposure period adjustment unit 1024.

[0042] Referring to FIG. 6B, the comparison information generated by the comparison unit 1020 is supplied to the light projection pulse width adjustment unit 1030. The light projection pulse width adjustment unit 1030 adjusts the light projection pulse width based on the comparison information, and this information is supplied to the light projection pulse generation unit 1040. The light projection pulse generation unit 1040 determines the light projection pulse width, and based on this light projection pulse width and a predetermined light projection period, the light projection switch circuit 534 (FIG. 6A) is controlled. The light projection pulse width adjustment unit 1030 and the exposure period adjustment unit 1024 constitute a feedback control unit 1032 for the peak light reception amount. The feedback control unit 1032 is feedback-controlled for the control of the exposure period, the light projection pulse width, and the light projection current amount based on the light reception information output by the light reception unit 64. Two operating modes of the green LD 520 may be prepared, and the first mode operating in class 1 and the second mode operating in class 2 may be selectively used properly. For example, it is preferable to select the first mode during optical axis adjustment and / or inspection, and the second mode can be selected during tuning and operation. Also, the light projection pulse width may be made settable by the user under certain restrictions.

[0043] That is, the light projection pulse width adjusted by the light projection pulse width adjustment unit 1030 is used for feedback control for controlling the current amount supplied to the green LD 520 by being reflected in the light reception amount target value 1042 of the monitor PD 522 (FIG. 6A). That is, the monitor light reception amount feedback control unit 1050 includes a comparison unit 1052 that compares the actual monitor light reception amount of the monitor PD 522 (FIG. 6A) with the monitor PD light reception amount target value 1042, and the comparison information by the comparison unit 1052 is supplied to the light projection current amount control unit 1054. The light projection current amount control unit 1054 generates a current amount control signal that decreases the light projection current amount when the actual monitor light reception amount is more than the target value 1042, and increases the light projection current amount when the actual monitor light reception amount is less than the target value 1042, and this current amount control signal is supplied to the current control circuit 532 (FIG. 6A). The above-described overcurrent signal is supplied to the failure detection unit (limiter) 1056, and when the failure detection unit 1056 receives the overcurrent signal, it cuts off the light projection current or regulates the light projection pulse generation unit 1040 and the light projection current amount control unit 1054 to suppress the overcurrent.

[0044] In FIG. 6B, the light projection control unit 680 including the peak position distance correspondence table 692 and the distance determination threshold value 694 is shown, but this is for drawing reasons to avoid line complexity, and it should be understood that the peak position distance correspondence table 692 and the distance determination threshold value 694 are registered in the memory.

[0045] Referring to FIG. 6B, the output of the gyro sensor constituting the above-described motion sensor 50 is input to the optical axis displacement detection unit 696. The optical axis displacement detection unit 696 reads a threshold value from the memory reference unit 698 and supplies optical axis displacement detection information to the output unit 690 when the output of the gyro sensor (motion sensor 50) is equal to or greater than the threshold value. This optical axis displacement detection information is supplied to the main body unit 4 through the communication unit 80.

[0046] The head unit 2 has a failure detection unit 1080. When an abnormality occurs in the operation of the head unit 2, the front operation indicator lamp 70 and the output unit operation indicator lamp 76 are driven through the indicator lamp control unit 1082, and the front operation indicator lamp 70 and the output unit operation indicator lamp 76 blink in red. Further, the indicator lamp control unit 1082 supplies an abnormality occurrence signal to the main body unit 4 through the communication unit 80, and the main body unit operation indicator lamp 14 blinks in red.

[0047] Figure 7 is a block diagram for explaining the control system of the main body unit 4. The main body unit 4 includes a processor 24, an input circuit 26, an output circuit 28, a power supply circuit 30, a communication unit 34, etc. The illustrated operation unit 402 means the SET button 16, the UP button 18, the DOWN button 20, and the mode button 22. By operating the operation unit 402, the user can perform tuning settings, mask settings, threshold value settings of the gyro sensor (motion sensor 50), output logic settings of the main body unit 4, clear input, etc. When an optical axis displacement is detected based on the signal of the motion sensor 50, an alarm signal is generated, and this alarm signal is held until a clear instruction is given. When the user operates the operation unit 402, this operation is received by the operation reception unit 240. When the user performs an operation to change, for example, the optical axis displacement threshold value or the distance determination threshold value, the optical axis displacement threshold value and the distance determination threshold value stored in the memory 32 are updated.

[0048] The measurement information including the received light information received from the head unit 2 through the communication unit 34 and the transmission / reception unit 340 is supplied to the output generation unit 246 through the transmission / reception unit 340. The output generation unit 246 generates a determination ON / OFF signal based on the determination data received from the head unit 2 and the output logic 248 that can be set by the user. The determination ON / OFF signal is supplied to an external device through the output cable 8 through the output circuit 28.

[0049] When the output generation unit 246 receives a fault detection signal or an optical axis displacement detection signal, it immediately supplies an alarm signal to the outside through the output circuit 28. Further, the output generation unit 246 supplies the optical axis displacement detection information to the display control unit 250, and the display control unit 250 controls the drawing of the OELD 12 based on the optical axis displacement detection information. The OELD 12 displays notification of the occurrence of an optical axis displacement.

[0050] The measurement information including the received light information including the determination threshold value received from the head unit 2 is supplied to the display control unit 250, and the display control unit 250 controls the drawing of the OELD 12 based on the measurement information including the received light information. The OELD 12 displays the measurement information.

[0051] FIG. 8 shows a display example of the OELD 12 when an abnormality such as an optical axis displacement occurs. The alarm display includes a first alarm display mode in which "position deviation detected" is displayed in characters, and a second alarm display mode in which the elapsed time from the time when it is detected that the displacement amount based on the angular velocity detected by the gyro sensor is equal to or greater than the threshold value is displayed. It is preferable to alternately display the first and second alarm display modes.

[0052] Figures 9 to 11 show display examples of the OELD 12 during operation or when setting a threshold value. During operation, a numerical display mode (Figure 9) and a bar display mode (Figures 10 and 11) can be selected. In the numerical display mode, the current value (199.9 mm in the illustrated example) and the threshold value (67.8 in the illustrated example) are numerically displayed (Figure 9). In the bar display mode, a distance mode (Figure 10) and a height mode (Figure 11) can be alternatively selected. In the bar display mode, a character C1 representing the head portion 2 is displayed. In the distance mode, the current value of the distance from the head to the work is displayed by a horizontal bar C3 (Figure 10). In the height mode, the current value of the displacement of the work from the reference plane is displayed by a horizontal bar C2 (Figure 11). In Figures 10 and 11, reference numeral C4 is a character of a vertical line including the character "P" indicating the maximum value of the detection values acquired so far. Further, reference numeral C5 is a character of a vertical line meaning the threshold value. When the user operates the UP / DOWN buttons 18 and 20 to change the setting of the threshold value, the threshold value character (vertical line) C5 moves following the user's operation, and the numerical value of the displayed threshold value changes. The user can adjust the threshold value while viewing the bar display of the current value of the OELD 12 and the display of the maximum value, and while checking the position of the threshold value character C5. Note that the numerical value "12.3" shown in Figures 10 and 11 means the current value.

[0053] Figure 12 is a diagram for explaining the power supply circuits included in the head portion 2 and the main body portion 4. The main body portion 4 incorporates a power supply circuit 30. The power supply circuit 30 includes two power supply circuits 30A and 30B. One of the power supply circuits 30A adjusts the voltage of the power supply received from the outside, and supplies the adjusted voltage to the other power supply circuit 30B and the head portion 2. The other power supply circuit 30B adjusts the voltage and supplies it to the processor 24 and the head portion 2. In the head portion 2, the motion sensor (gyro sensor) 50 and the processor 68 are driven by the power supply received from the main body portion 4, and the green LD 520 is also driven. The second power supply circuit 78 in the head portion 2 adjusts the voltage, and after the adjusted voltage is stabilized by the linear regulator 82, it is supplied to the imaging element 60 and the light receiving circuit 62.

[0054] FIG. 13 is a flowchart for explaining the control of the processor 68 that restricts the intensity and power of the LD520 (FIG. 6) that emits green laser light. Referring to FIG. 13, at step S1, the light projection pulse generation unit 1040 (FIG. 6B) generates a light projection signal at a predetermined light projection period. In the next step S2, the green LD520 is driven with a preset current amount. In the next step S3, the monitor light reception amount feedback control unit 1050 in the light projection control unit 680 of the processor 68 determines whether or not the amount of received light received by the monitor PD522 (FIG. 6A) is within a preset range. When NO, that is, when the amount of received light deviates from the specified range, the process proceeds to step S4 to determine whether or not this deviation has continued for a predetermined number of times or more. When YES in this step S4, that is, when the deviation has continued for a predetermined number of times or more, it is assumed that some abnormality has occurred, and the light projection of the green LD520 is stopped (S5). When NO in step S4, the process proceeds to step S6, the current amount for controlling the green LD520 is adjusted, and the process returns to step S2. As described in step S3 and the like, by monitoring the monitor light emission amount at a plurality of locations, even if one location fails, it is possible to ensure operation based on a laser class that can ensure a predetermined safety.

[0055] The above steps S3 to S6 constitute a substantial limiter that restricts the intensity and power of the green laser light. The intensity and power of the green laser light emitted by the light projection unit 52 are restricted to a level that does not affect the user even when the user visually confirms the position of the spot of the green laser light hitting the workpiece with the naked eye. This restriction may be set with the "Class 1" or "Class 2" of the safety standard in mind. Green has a wavelength of 500 nm to 555 nm and its relative visual sensitivity (bright relative visual sensitivity and dark relative visual sensitivity) is superior to other colors. Therefore, even if the intensity and power of the green laser light are restricted to the above levels, the visibility of the spot can be ensured.

[0056] Two operating modes of the green LD520 may be provided, and depending on the user's settings, the first mode that operates in Class 1 and the second mode that operates in Class 2 may be selectively used. For example, the first mode may be selected during optical axis adjustment and / or inspection, and the second mode may preferably be selectable during teaching and operation. Also, the user may be able to set the projection pulse width under certain restrictions.

[0057] In the triangulation distance sensor 100, control is executed to keep the received light signal at an appropriate signal intensity in order to correctly calculate the distance from the received light signal. FIG. 14 is a diagram for explaining the problems when the received light amount is too large and when it is too small. (I) of FIG. 14 shows the case where the received light amount is too large. When the received light amount exceeds the saturation point, the peak portion of the received light waveform disappears, so the position of the peak cannot be accurately grasped. (II) of FIG. 14 shows the case where the received light amount is too small. When the received light amount is small, the peak of the received light waveform becomes overall low, so the peak position cannot be accurately grasped. Referring to (III) of FIG. 14, the exposure time of the imaging device 60 is controlled by an electronic shutter (not shown). In the embodiment, by changing the exposure time based on the peak light amount of the received light signal, when the received light amount is too large, the exposure time is shortened to reduce the received light amount and lower the peak of the received light waveform, and when the received light amount is too small, the exposure time is lengthened to increase the received light amount and raise the peak of the received light waveform. By changing the exposure time of the imaging device 60, the received light amount of the imaging device 60 changes.

[0058] Regarding the control of the received light amount performed for the optimization of the peak of the received light waveform, in addition to the exposure time described above, the received light gain of the circuit that amplifies the received light signal, or the emission power of the green LD520 may be changed to control the intensity of the emission signal. To distinguish it from the signal due to ambient light, it is preferable to increase the emission power of the green LD520. On this premise, it is advisable to perform control to appropriately adjust the peak of the received light waveform according to the exposure time and received light gain of the image sensor 60. The control by the exposure time of the image sensor 60 has the advantage of being relatively easy to introduce, but in order to expand the adjustable dynamic range, it is advisable to adopt a combination of the received light gain or emission power and the exposure time.

[0059] As described above, the green laser light has the advantage of high relative visibility and good visibility for workpieces with low reflectivity. However, for workpieces with high reflectivity, such as white workpieces or metal workpieces, there is a possibility that the user may feel that the spot is too dazzling. A spot that feels dazzling may interfere with optical axis adjustment and the like. From this perspective, it is preferable to perform control to change the emission power according to the surface properties of the workpiece. As a specific example, an example of control for changing the pulse width of the light projection in addition to changing the exposure time is the flowchart shown in FIG. 15. Instead of the light projection pulse width, the current value may be changed. If the light projection pulse width is equal to or longer than the exposure time of the image sensor 60, the detection performance of the sensor will not be degraded.

[0060] Referring to FIG. 15, the light intensity control process is executed in step S11. FIG. 16 is a flowchart for explaining an example of the light intensity control process. In step S111 of FIG. 16, a light emission signal is generated by the light emission pulse generation unit 1040 at a predetermined light emission period. In the next step S112, the light emission unit 52 is controlled with the set current amount and light emission pulse width. In step S113, it is determined whether the received light amount received by the monitor PD522 used for feedback control of the light emission amount is within a specified range. If the result is NO, the process proceeds to step S114, where it is determined whether the number of times of deviating from the specified range is within a predetermined number of times. This predetermined number of times depends on the regulations of the laser class set by the user, and when the regulations of the laser class cannot be guaranteed, a signal for stopping the light emission pulse is generated (S115). When there is no problem from the perspective of the laser class that ensures the safety of the optical power of the controlled green LD520, a signal for stopping the light emission pulse may be generated only when the response time cannot be guaranteed. In step S114, if the number of times of deviating from the specified range is within the predetermined number of times, the process proceeds to step S116 with a YES, and the current amount for controlling the light emission is set.

[0061] Returning to the flowchart of FIG. 15, in step S12, the light emission pulse generation unit 1040 (FIG. 6B) determines whether there is a signal for stopping the light emission pulse. If there is a stop signal, the process proceeds to step S13 to stop the light emission. If there is no signal for stopping the light emission pulse in step S12, the process proceeds to step S14 to execute the overcurrent detection process.

[0062] FIG. 17 is a flowchart for explaining an example of the overcurrent detection process. In step S141 of FIG. 16, the current flowing through the green LD520 is converted into a voltage and compared with the reference voltage for overcurrent detection, and it is determined whether the voltage based on the current flowing through the green LD520 is within the reference voltage for overcurrent detection (S142). When the voltage based on the current flowing through the green LD520 is higher than the reference voltage for overcurrent detection, the process proceeds to step S143 with a NO to generate an overcurrent detection signal, and also a signal for stopping the light emission pulse is generated (S144).

[0063] Returning to FIG. 15, in step S15, it is determined whether there is a light projection pulse stop signal. If there is a light projection pulse stop signal, the process proceeds to step S13 to stop the light projection. If there is no light projection pulse stop signal, the process proceeds to step S16, and the imaging element 60 is driven at the set timing and exposure period, and a light reception signal is acquired according to the amount of received light during the exposure period (S17). Then, in the next step S18, it is determined whether the maximum value of this light reception signal is within the target range. If the maximum value of the light reception signal is within the target range, it means YES and the process proceeds to step S19 to integrate the amount of received light of each light reception pixel to generate a light reception waveform. In the next step S20, the position of the peak of the light reception waveform is calculated, and the displacement (position) of the workpiece is calculated from this peak position (S21), and information based on the calculated displacement of the workpiece is output (S22), and the process returns to step S11. The output in step S22 may be to output the displacement of the workpiece or to generate a determination ON / OFF signal by comparing with a threshold value.

[0064] The calculation of the peak position of the light reception waveform in step S20 is performed as follows. (1) When the peak position can be obtained from the light reception waveform, it is determined as the obtained peak position. (2) When the amount of received light is excessively large and saturated, the peak position is estimated from the obtained light reception waveform. (3) When the amount of received light is too small to fall within the target range and the peak position can be obtained, it is determined as the obtained peak position. (4) When the amount of received light is too small to detect the peak position, it is assumed that the workpiece exists at the farthest or nearest position set in advance.

[0065] If the maximum value of the light reception signal is not within the target range in step S18 above, the process proceeds to step S24 to change the settings of the exposure time and light projection pulse width in order to optimize the amount of received light, and the process returns to step S11 above.

[0066] FIG. 18(I) is a diagram for explaining that in the image pickup device 60 made of, for example, CMOS, the part that receives the reflected light varies depending on the distance of the workpiece. In the illustrated example, when the workpiece is located at a short distance, the image of the spot is formed at the lower part of the image pickup device 60 (FIG. 18(II)). And as will be described next, the image of the spot is relatively large. On the other hand, when the workpiece is located at a long distance, the image of the spot is formed at the upper part of the image pickup device 60. And as will be described next, the image of the spot is relatively small (FIG. 18(II)). As will be described later, the group of pixels 60a of the image pickup device 60 is preferably designed such that the width of the pixel 60a increases as the workpiece moves from the part that receives light when the workpiece is located at a long distance to the part that receives light when the workpiece is located at a short distance. Here, the width of the pixel 60a substantially means the distance between the center of the first pixel and the center of the second pixel in two adjacent pixels 60a.

[0067] FIG. 19 is a diagram for explaining that in the image pickup device 60 composed of a plurality of pixels 60a, the part that receives the image SP of the spot varies depending on the distance of the workpiece, and the size of the image SP of the spot also changes. FIG. 19(I) shows that when the workpiece is located at a short distance, the spot is formed at one end of the group of pixels 60a of the image pickup device 60. FIG. 19(II) shows that when the workpiece is located at an intermediate position, the spot is formed at the middle part of the group of pixels 60a of the image pickup device 60. FIG. 19(III) shows that when the workpiece is located at a long distance, the spot is formed at the other end of the group of pixels 60 of the image pickup device 60.

[0068] As can be seen from FIG. 19(I), when the workpiece is located at a short distance, the image SP of the spot is large, and when the workpiece is located at a long distance, the image SP of the spot is small (FIG. 19(III)). When the pixels 60a of the image pickup device 60 are arranged at equal intervals, in the illustrated example, when the workpiece is close, it is received by 7 pixels 60a. In contrast, when the workpiece is far, it is received by 1 pixel 60a.

[0069] When the workpiece is located nearby and the spot image SP is received by a plurality of pixels 60a (Fig. 19(I)), the number of pixels 60a that receive light is large, and since the received light waveform can be approximated curvilinearly based on the received light data of the plurality of pixels 60a, the accuracy of estimating the position of the peak of the received light amount becomes high. On the other hand, when the workpiece is located far away and the spot image SP is received by, for example, one pixel 60a (Fig. 19(III)), the received light waveform cannot be approximated curvilinearly, so the peak position of the received light amount cannot be estimated. In order to approximately curve-fit the received light waveform even when the workpiece is far away, it is desirable to reduce the width of each of the light-receiving pixels 60a. On the other hand, when the width of each of the light-receiving pixels a is reduced, the number of pixels in the entire image sensor increases, and the processing load increases.

[0070] Regarding this problem, it is preferable to design the image sensor 60 mounted on the head unit 2 such that the width of the pixel 60a varies corresponding to the distance of the workpiece. FIG. 20 is a conceptual diagram for explaining an example in which the image sensor 60 is designed such that the width of the pixel 60a gradually decreases from the near side to the far side. FIG. 20 is an image diagram of the image sensor 60 having unequally spaced pixels 60a. The size of the image SP of the spot imaged by the image sensor 60 is determined corresponding to the detection range of the head unit 2. (I) of FIG. 20 shows the imaging position of the spot and the image SP of the spot when the workpiece is located at a short distance. (II) of FIG. 20 shows the imaging position of the spot and the image SP of the spot when the workpiece is located at an intermediate distance. (III) of FIG. 20 shows the imaging position of the spot and the image SP of the spot when the workpiece is located at a long distance. In the illustrated example, the width of the pixel 60a is defined such that the image SP of the spot is received by three pixels 60a regardless of the distance of the workpiece. Thereby, the peak position can be estimated by curve-fitting the received light amounts of the three pixels 60a that receive the image SP of the spot regardless of the distance of the workpiece. In addition, the number of pixels of the entire image sensor can be reduced, and since the image is not received by many pixels 60a, the processing load can also be reduced. Thereby, both the detection accuracy of the peak position and the reduction of the processing load can be achieved. In the illustrated example, the image SP of the spot is received by three pixels 60a. This is based on the reason that in order to approximately represent the received light waveform in a curve, it is preferable to receive the image SP of the spot with at least three pixels 60a.

[0071] Note that in FIG. 20, the image SP of the spot is represented by a circle or an ellipse, but the shape of the image SP of the spot is not limited to a circle or an ellipse and may be a rectangle.

[0072] FIG. 21 is a diagram for explaining the structure of the light transmitting / receiving surface 2a of the head unit 2. The head unit 2 has a relatively narrow side surface that constitutes the light transmitting / receiving surface 2a. This light transmitting / receiving surface includes a light guiding member holder 79 that forms the light transmitting / receiving windows 66 and 68, and a light diffusing member 70c that guides and diffuses the light of the first operation display lamp unit 72 located on the light transmitting / receiving surface 2a, i.e., the front surface of the head unit 2, outward. The light diffusing member 70c is mounted between the light projecting window 66 and the light receiving window 67 of the light guiding member holder 79. In the figure, reference numerals 70a and 70b indicate the light sources of the unitized front operation display lamp 70, 70a is a red LED, and 70b is a green LED.

[0073] A waterproof packing 84 is disposed outside the light guiding member holder 79, and a light transmitting cover member 86 is disposed outside thereof. This light transmitting cover member 86 is fixed by a metal cover pressing member 88. By snap-fitting the metal cover pressing member 88 to the first housing 2, the waterproof packing 84 is compressed, thereby waterproofing the light transmitting / receiving surface 2a.

[0074] The waterproof structure of the head unit 2, that is, substantially the same waterproof structure as the waterproof packing 72 (FIG. 5) for the relay cable 6 and the waterproof packing 84 for the light transmitting / receiving surface 2a is also adopted for the main body unit 4. The main body unit 4 has a waterproof structure including the area around the OELD 12, the operation unit 402, the connection parts of the relay cable 6, and the output cable 8.

[0075] Reference numeral Th in FIGS. 1, 5, and 21 indicates a mounting hole. The mounting hole Th is a through hole extending in a direction orthogonal to the direction of the optical axis of the green laser light, and the head unit 2 is fixed at an arbitrary position by bolts inserted into two mounting holes Th that cross it.

[0076] FIG. 22 is a diagram for explaining that the relay cable 6 and the output cable 8 are connected to the main body substrate 36 built in the main body 4 by soldering without connectors. Note that reference sign C indicates the contact point of the main body substrate 36. Specifically, the relay cable 6 is connected to the flexible substrate 38, and the flexible substrate 38 is soldered to the main body substrate 36. Note that the other end of the relay cable 6 is soldered to the head unit 2. That is, the head unit 2 and the main body 4 are connected by soldering both ends of the relay cable 6. Thereby, the head unit 2 and the main body 4 can be substantially integrated in the circuit configuration. Regarding the output cable 8, the contact point of the vertical relay member 40 is soldered to the contact point C of the main body substrate 36. Thereby, the overall length of the main body 4 can be shortened. As a modification, a connector may be provided at the end of the main body 4 on the head unit 2 side, and the main body 4 and the relay cable 6 may be connected via this connector. Further, a connector may be provided at the output side end of the main body 4, and the output cable 8 may be connected to this connector.

[0077] FIGS. 23 to 26 are diagrams for explaining the water stop structure at both ends of the main body 4. The main body 4 has caps 102 at both ends. FIGS. 23 and 24 show a state in which the cap 102 on the head unit 2 side is loosened. FIG. 23 is a side view, and FIG. 24 is a cross-sectional view. FIG. 25 is an enlarged view of the portion indicated by arrow XXV in FIG. 24. Reference sign 104 is a water stop member, that is, a packing. By tightening the cap 102, the packing 104 stops the water. FIG. 26 is a cross-sectional view corresponding to FIG. 25, showing the state after the cap 102 is tightened. As can be seen from FIG. 26, by tightening the cap 102, the gap between the cap and the main body 4 disappears, and the packing 104 is in a compressed state.

[0078] In FIG. 15, reference sign 108 indicates a threaded portion. In FIGS. 23 and 24, a neck portion N is formed inside the cap 102 on the right side in the tightened state.

[0079] <Second Embodiment (FIGS. 27 to 31)> The displacement sensor of the second embodiment is an optical triangulation sensor equipped with a green laser light source, similar to the first embodiment. The triangulation sensor 200 of the second embodiment is divided into a head body 202 that constitutes the first housing and a relay unit 204 that constitutes the second housing. The relay cable 204 extending from the head body 202 is integrated with the relay unit 204. Also, the external connection cable 212 extending from the relay unit 204 is integrated with the relay unit 204. That is, both the relay cable 204 and the external connection cable 212 extend from the relay unit 204 without connectors.

[0080] In the triangulation sensor 200 of the second embodiment, the relay unit 204 is composed of a power circuit and does not have a display function. From this, the displacement sensor of the second embodiment can be said to be a displacement sensor without a display function. Therefore, the usage mode of the triangulation sensor 200 of the second embodiment is, as shown in Fig. 27, a mode of connecting to a PLC or control equipment, or if the user requires a display, a mode of connecting to a separate amplifier with a conventional display function.

[0081] Figs. 28A and 28B are block diagrams for explaining the configuration of the head body 202 included in the second embodiment. The configuration of the head body 202 is the same as that of the head unit 2 included in the first embodiment, as can be seen by comparing with Figs. 6A and 6B described above. The head body 202 is composed of the minimum necessary elements for measurement using a green laser light source, similar to the head unit 2 included in the first embodiment.

[0082] As described in the first embodiment with reference to Fig. 6B, the distance determination unit 688 (Fig. 28B) generates a binary determination signal that is binarized to ON / OFF by comparison with the determination threshold value 694 stored in the memory. This ON / OFF determination signal is supplied to an external device through the output unit 690, the communication unit 80, and via the relay unit 204 and the external connection cable 212.

[0083] FIG. 29 is a diagram for explaining the power supply circuit included in the triangulation distance sensor 200 of the second embodiment. The triangulation distance sensor 200 is driven by a power supply supplied from an external device that can be connected thereto, that is, a PLC, a separation amplifier, and a control device. FIG. 29 shows an example in which the triangulation distance sensor 200 is connected to the separation amplifier 300. The separation amplifier 300 includes a first power supply circuit 302 and a second power supply circuit 304 that steps down the voltage generated by the first power supply 302, and the processor 306 of the separation amplifier 300 is driven by the second power supply circuit 304.

[0084] The relay unit 204 included in the triangulation distance sensor 200 is connected to an external device such as the separation amplifier 300 through the external connection cable 212. The voltage adjusted by the first power supply circuit 302 of the separation amplifier 300 is supplied to the triangulation distance sensor 200 through the external connection cable 212 to drive the green LD 520. The third power supply circuit included in the relay unit 204 steps down the voltage generated by the first power supply circuit 302 to generate a power supply for driving the processor 68 of the head main body unit 202. The head main body unit 202 includes a fourth power supply circuit 78, and this fourth power supply circuit 78 steps down the potential supplied from the first power supply circuit 302. The fourth power supply circuit 78 adjusts the voltage for driving the imaging element 60 and the light receiving circuit 62.

[0085] The relay unit 204 has an elongated cylindrical shape and has a larger diameter than the relay cable 210 and the external connection cable 212, but has a diameter that is several times larger. From this, the relay unit 204 is substantially integrated morphologically with the relay cable 210 and the external connection cable 212. Also, the outer shape of the relay unit 204 is designed to be integrated morphologically.

[0086] The relay unit 204 is connected to the relay cable 210 and the external connection cable 212 without a connector. The housing 220 of the relay unit 204 is made of resin. The same water stop structure as the main body unit 4 described above is also adopted in the relay unit 204. That is, one end of the resin housing 220 has a packing 222 that stops water around the first relay cable 210, and the packing 222 is compressed by the cap 224 around it (FIG. 30).

[0087] Referring to FIG. 31, for the triangulation sensor 200 of the second embodiment, the distance data, ON / OFF determination result, and optical axis displacement information generated by the head body 202 can be supplied to the separate amplifier 300, PLC, and control device through the external connection cable 212. That is, it can be used as a displacement sensor without a display function.

[0088] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to a laser displacement sensor that projects a laser beam. The present invention is not limited to the type of light source and is applicable to triangulation types and TOF (Time Of Flight) types. It is also applicable to a light-receiving amount type photoelectric sensor.

Explanation of Reference Numerals

[0089] 100 Triangulation sensor of the first embodiment 2 Head portion constituting the first housing 4 Body portion constituting the second housing Sm Protrusion 6 Relay cable 32 Memory 52 Light projection portion 520 Green laser diode 60 Image sensor (CMOS) 64 Light receiving portion 70 Front operation indicator light of the head portion 76 Output portion operation indicator light of the head portion 402 Operation portion 200 Triangulation sensor of the second embodiment 202 Head body constituting the main body housing 204 Relay portion constituting the relay housing 212 External connection cable 30, 78, 230, 232 Power supply circuit

Claims

1. A first housing having a transmission window for transmitting light; A cable for transmitting power to the first housing; A second housing connected to the first housing via the cable and having at least a first power supply circuit for supplying power of a first voltage to the first housing via the cable and integrated with the cable; The first housing includes: A semiconductor laser light source that projects measurement light toward a detection region through the transmission window; A second power supply circuit that steps down the voltage received from the first power supply circuit; An imaging element that is driven by the power supplied from the second power supply circuit and photoelectrically converts the measurement light from the detection region through the transmission window to generate a received light signal; A measurement unit that measures the displacement of a detection target based on the received light signal generated by the imaging element; An optical displacement sensor, wherein the semiconductor laser light source driven by the power supplied from the first power supply circuit is driven at a voltage higher than that of the imaging element.

2. The second housing has a waterproof structure, The waterproof structure includes a packing disposed around the end of the cable and a cap that compresses and deforms the packing. The optical displacement sensor according to claim 1.

3. The second housing further includes: A receiving circuit that receives measurement information generated by the measurement unit of the first housing, and a display unit that displays information related to displacement based on the measurement information received by the receiving circuit. The optical displacement sensor according to claim 1 or 2.

4. The second housing further includes: An operation unit for setting a determination threshold value, The display unit displays measurement information based on the determination threshold value set based on an operation instruction of the operation unit and the displacement measured by the measurement unit. The optical displacement sensor according to claim 3.

5. The second housing has a plurality of surfaces, and the operation unit is provided on a third surface different from a first surface on which the display unit is provided and a second surface facing the first surface. The optical displacement sensor according to claim 4.

6. On the third surface, a raised portion is formed to prevent misoperation of the operation unit. The optical displacement sensor according to claim 5.

7. The second housing is integrally connected to the first housing via the cable, The second housing is composed of a power supply circuit. The optical displacement sensor according to claim 1.

8. The semiconductor laser light source of the first housing includes a green semiconductor laser that emits green laser light, The first power supply circuit of the second housing supplies power for driving the green semiconductor laser. The optical displacement sensor according to any one of claims 1 to 7.

9. The optical displacement sensor is A timing control unit that controls the light projection timing of the semiconductor laser light source, A monitor light receiving element that receives the laser light from the semiconductor laser light source and generates a light reception signal according to the amount of received light, A light intensity control unit that controls the light intensity of the laser light projected by the semiconductor laser light source based on the light reception signal generated by the monitor light receiving element, The optical displacement sensor according to any one of claims 1 to 8, further comprising a light source control unit that monitors the state of the semiconductor laser light source and controls the optical power of the laser light projected toward the detection region within a predetermined range.

10. A first operation indicator light for indicating a comparison result generated by comparing the displacement of the detection target measured by the measurement unit with a determination threshold value is provided on the first housing, A second operation indicator light that lights or blinks in the same color in synchronization with the first operation indicator light is provided on the second housing. The optical displacement sensor according to any one of claims 1 to 9.

Images