Photoelectric safety switch

Abstract

A photoelectric switch which projects and receives light to detect the presence of an object in a predetermined two-dimensional or three-dimensional protection zone using the light from the object within the protection zone, and which is provided with a user-adjustable safety function, the photoelectric switch comprising: a controller configured to determine an ON or OFF state as a first safety signal signifying an operation permit / non-permission for an external device based on the presence of the object within a first protection area of ​​the protection area and a first setting of the safety function, and to determine an ON or OFF state as a second safety signal signifying an operation permit / non-permission for an external device based on the presence of the object within a second protection area of ​​the protection area and a second setting of the safety function, wherein the safety function is related to a suppression function or a blocking function; and a plurality of output systems with a first output system associated with the first safety signal and with a second output system associated with the second safety signal, wherein the first setting of the security function and the second setting of the security function are individually user-adjustable with respect to each of the plurality of output systems.

Description

BACKGROUND OF THE INVENTIONField of the invention

[0001] The present invention relates to a photoelectric safety switch. Description of the state of the art

[0002] As shown in Japanese Patent Application Publication No. H4-310890 and Japanese Patent Application Publication No. H3-175390, an optical scanning photoelectric switch is known that performs two-dimensional light scanning to detect an object while detecting the position of that object. Also referred to as a safety scanner, safety laser scanner, and the like, this optical scanning photoelectric switch establishes a protective zone around a machine, robot, or the like as a hazardous source and outputs a safety signal to the hazardous source, prohibiting its operation if an operator or the like enters this protective zone.

[0003] A photoelectric switch used as a safety device is not limited to the optical scanning photoelectric switch mentioned above. Multiple optical axis photoelectric switches and single optical axis photoelectric switches are also known. The multiple optical axis photoelectric switch is used to form a light curtain at the entrance of a protected area. This multiple optical axis photoelectric switch incorporates a blanking function as a safety function, which temporarily disables the entire light curtain or part of its area.For this purpose, the gap function is known as the floating gap function, which specifies the numbers of optical axes, and the fixed gap function, which specifies the number of an optical axis (Japanese Patent Application Publication No. 2002-296361, Japanese Patent Application Publication No. 2003-20147).

[0004] EP 1 742 086 A1 additionally discloses a system and a method for creating a safety zone in the surroundings of a vehicle, in which the safety zone is divided into different fields and, for example, a deceleration path is determined based on the fields.

[0005] DE 102 40 438 A1 relates to a method for operating a monitoring device and to a monitoring device in which a monitoring area is monitored with an optoelectronic sensor and a working area which at least partially coincides with the monitoring area is illuminated.

[0006] Finally, DE 10 2008 005 544 A1 concerns a photoelectric sensor with multiple optical axes. PRESENTATION OF THE INVENTION

[0007] For example, a basic conventional idea is that when there are a plurality of danger sources in a danger area, a photoelectric switch is arranged with respect to each danger source to ensure the safety of the operating personnel, and the basic conventional idea is further that when one output (output quantity) of a photoelectric switch is used for a plurality of safety controllers, the aforementioned safety trigger devices or a safety PLC (safety programmable logic controller) is used.

[0008] Although the safety PLC is versatile in that it allows a user to set up various controls through programming, it is impractical from a safety verification perspective in that another device is required to verify a user-created program. Furthermore, even if one considers from another perspective that multiple hazard sources exist in a hazardous area, it makes no difference, since the hazardous area is one, and arranging multiple photoelectric switches to ensure safety in that single hazardous area is undesirable for the user from a cost perspective.

[0009] In addition, a problem specific to photoelectric optical scanning switches is that when a plurality of photoelectric optical scanning switches are arranged in a hazardous area, the problem of mutual interference (interference) may occur between these photoelectric optical scanning switches because the photoelectric optical scanning switch performs scanning with light over a wide area. Although the interference problem can be naturally solved by adjusting the installation position or height of the photoelectric optical scanning switch in its arrangement, such adjustment means that a limitation on the arrangement of the photoelectric optical scanning switch arises, and, for example, the problem that a plane cannot be protected at the same height.

[0010] Accordingly, it is an object of the present invention to provide a photoelectric switch capable of reducing the cost burden on the user while ensuring the protective function inherent in its safety devices without compromising its safety function.

[0011] According to the present invention, the technical problem is solved by providing a photoelectric switch according to claim 1 or 9, which projects and receives light to detect the presence of an object within a predetermined two-dimensional or three-dimensional protection area by means of light from the object in the protection area, and is equipped with a user-adjustable safety function, wherein at least a plurality of first and second output systems are provided and the safety function or the protection area is user-adjustable with respect to each input system.

[0012] According to the photoelectric switch of the present invention, since a photoelectric switch has a plurality of output systems capable of individually setting different safety functions or protection areas, it is possible to provide an apparatus for rationally performing safety control on a plurality of danger sources without using the safety PLC as conventionally.

[0013] According to a preferred embodiment of the present invention, an inspection signal is superimposed on each output of the plurality of output systems at different times in a time-division manner. With the superimposed inspection signal, a fault (failure) can be measured even if a short circuit occurs between the safety outputs of the plurality of systems, thus ensuring the reliability of the safety control system by using a photoelectric optical scanning switch.

[0014] Further, in a preferred embodiment of the present invention, a detection capability of the photoelectric switch is adjustable by the user, and the detection capability is adjustable with respect to each output system by the user.

[0015] Since according to this embodiment it is possible to individually set different detection capabilities for each output system, safety control can be carried out rationally at a variety of hazard sources without using safety triggering devices as is conventional.

[0016] The cited safety function may be an interlock function that prevents the safety output of the photoelectric switch from changing from an OFF state to an ON state. Furthermore, in the multi-optical-axis photoelectric switch and the optical scanning photoelectric switch that form a light curtain with multiple optical axes, a blanking function or a muting function that temporarily disables the optical axes of all or part of the light curtain may be cited as examples of the safety function. SHORT DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining the basic concepts of a photoelectric optical scanning switch; Fig. 2 is a view for explaining an application example of a photoelectric optical scanning switch according to the present invention; Fig. 3 is a view for explaining the structure of an optical system of the photoelectric optical scanning switch according to the present invention; Fig. 4A is a diagram showing an overall configuration of the photoelectric optical scanning switch of the Fig. 3 shows, and Fig. Fig. 4B is a view for explaining a protection area and a warning area; Fig. 5 is an external view of the photoelectric optical scanning switch according to the present invention; Fig. 6A is a front view of the photoelectric optical scanning switch according to the present invention, and Fig. 6B is a view of a portion of a user interface extracted and viewed from the user's side; Fig. 7 is a vertical sectional view for explaining an internal structure of the photoelectric optical scanning switch according to the present invention; Fig. 8 is one with Fig. 5 is a related view wherein a light-transmitting cover constituting a light-shielding window is removed from the optical scanning photoelectric switch; Fig. 9 is a perspective view of a device body showing the internal structure of the photoelectric optical scanning switch according to the present invention, and a view showing a state in which a scanning mirror faces the opposite side of a measuring area; Fig. 10 is a sectional view of the device body of the Fig. 9; Fig. 11 is a plan view of two kinds of reflecting surfaces, namely white and black, as reference objects, which have different reflection factors and are incorporated in the photoelectric optical scanning switch; Fig. Fig. 12 is a view showing a state where a laser light pulse is irradiated onto the two reflecting surfaces of the Fig. 11 is projected as reference objects; Fig. 13 is a view showing the photoelectric optical scanning switch connected to a personal computer on which a program for setting the protection area and the warning area is installed; Fig. 14 is a functional block diagram for setting the protection area; Fig. 15 is an image displayed on a screen of the personal computer when setting an area; Fig. 16(a) to 16(c) are views for explaining a method of setting the protection area; Fig. 17(a) to 17(c) are views for explaining another method of setting the protection area; Fig. 18 is a diagram of the area setting during the initial setting of the protection area by setting a suppression area (muting area); Fig. 19 is a diagram of the area setting in the intermediate process of setting the suppression area (muting area) in the Fig. 18 set protection area; Fig. 20 is a diagram for explaining the protection area in which the suppression area (muting area) has been set; Fig. 21 is the picture of the suppression setting for setting a variety of functions as well as the suppression time in the suppression range; Fig. Fig. 22 is a view showing the overall structure of a transport system in which the suppression range is set in the photoelectric optical scanning switch; Fig. 23 is a functional block diagram of the photoelectric optical scanning switch according to a suppression function; Fig. 24(a) to 24(c) are views for explaining the relationship between a plurality of suppression sensors and a workpiece; Fig. 25(d) and Fig. 25(e) are views for explaining the relationship between the plurality of suppression sensors and the workpiece according to the state of Fig. 24; Fig. 26 is a suppression time diagram; Fig. Fig. 27 is a view for explaining a gate structure in which a plurality of suppression areas are set and the suppression areas are controlled by the switch according to the type of object; Fig. 28 is, together with Fig. 27 is a view for explaining that a relatively low suppression range is set when a relatively low object passes through the gate; Fig. 29 is, together with Fig. 27 is a view for explaining that a relatively high suppression range is set when a relatively high object passes through the gate; Fig. 30 is a view for explaining a gate structure in which sensors are installed at three different heights to detect the height of the object, and the suppression area is switched based on the height of the object detected by the sensors; Fig. 31(a) is an explanatory view, together with Fig. 30, that a low suppression range corresponding to a low object is set when a low object is detected, and Fig. 31(b) is a view for explaining that a moderately high suppression area corresponding to a moderately high object is set when a moderately high object is detected; Fig. 32(c) is an explanatory view, together with Fig. 30 and Fig. 31, that a high suppression range corresponding to a high object is set when a high object is detected, and Fig. 32(d) is a view for explaining that when the comparatively highest object is detected, a very high suppression area corresponding to that very high object is set; Fig. 33 is a view for explaining an example in which the photoelectric optical scanning switch is installed on a traveling truck and the protection area is switched according to a path traversed by the traveling truck; Fig. 34 is a view for explaining an example in which a photoelectric optical scanning switch provided with outputs of a plurality of systems is employed; Fig. 35 is a block diagram for explanation, together with Fig. 34, the operation of the photoelectric optical scanning switch provided with the outputs of two systems; Fig. 36 is a timing chart for explaining an example in which an inspection signal is phased at each output of a plurality of systems by superimposing the inspection signal on a safety signal; Fig. 37 is a view for explaining that interference between two adjacent photoelectric optical scanning switches may occur as a problem; Fig. 38 is a timing chart for the projection of light pulses when interference occurs between the two photoelectric optical scanning switches; Fig. 39 is a view for explaining a state in which laser light is radially projected by rotating a scanning mirror of the photoelectric optical scanning switch; Fig. 40 is a diagram for explaining a light projection duration of the light projection pulse; Fig. 41 is a diagram for explaining a revolution period of the scanning mirror, ie, the scanning period; Fig. 42 is a diagram for explaining an example of control in which the light projection duration is set differently between adjacent optical scanning photoelectric switches so as to prevent interference; Fig. 43 is a diagram showing, in block form, a basic configuration of the photoelectric optical scanning switch according to the present invention; Fig. 44 is a diagram for explaining an example of control in which a plurality of optical scanning photoelectric switches are mutually connected and the timing of light projection is phased to prevent interference; Fig. 45 is a diagram for explaining an example of control in which the timing of light projection is phased when interference is measured in adjacent photoelectric optical scanning switches; Fig. 46 is a diagram for explaining a change in the display state of a liquid crystal display section installed in the user interface section of the optical scanning type photoelectric switch to which the present invention is applied; Fig. 47 is a diagram for explaining the display change in an observation mode of the Fig. 46; Fig. 48 is a diagram for explaining the display change in a setting mode of the Fig. 46; Fig. 49 is a view for explaining that, by using a personal computer as a terminal having a display connected to the photoelectric optical scanning switch, the direction of generation of noise light can be displayed on the screen of the personal computer; Fig. 50 is a diagram for explaining that an error due to noise is displayed in the liquid crystal display section of the photoelectric switch of the optical pickup; Fig. Figure 51 is a flowchart explaining a specific technique for measuring disturbances; Fig. 52 is a view showing an example in which an indicator indicating the direction of disturbance is installed in the optical scanning photoelectric switch; Fig. 53 is a flowchart for explaining a method for autonomously maintaining a detection sensitivity using a reference object built into the optical scanning photoelectric switch and storing a reference light receiving intensity in a memory at the time of factory shipment, which is required when contamination of the reference object or the like is considered as a failure of the optical scanning photoelectric switch; Fig. 54 is a flowchart for explaining a processing method for autonomously maintaining the detection sensitivity of the photoelectric optical scanning switch by means of the method of Fig. 53 reference light reception intensity recorded in the memory; and Fig. Fig. 55 is a flowchart for explaining a processing method for switching the optical scanning photoelectric switch to a safety state when contamination or the like of the reference object built into the optical scanning photoelectric switch is detected by the reference light receiving intensity which is determined by the process of Fig. 53 was written into memory when the contamination was generated or something similar. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples

[0017] With reference to Fig. 1, the basic terms of a photoelectric optical scanning switch are described as generally applicable rules: "measuring range"; "maximum protection range"; "warning range"; and "protection range." The "maximum protection range" means a region in which the photoelectric optical scanning switch can detect objects with a variety of reflection factors, from an object with a low reflection factor to an object with a high reflection factor, as specified by the safety standard. The "measuring range" means a region in which an object with a standard reflection factor can be detected by the photoelectric optical scanning switch, and this "measuring range" completely encompasses the "maximum protection range."

[0018] As is known, the photoelectric optical scanning switch is used to two-dimensionally scan the maximum protection area with light such as laser light and observe the scanning light reflected from the maximum protection area, thereby monitoring the safety in the area.

[0019] The "measuring range" and "maximum protection range" are specific to each photoelectric optical scanning switch and are not user-adjustable. On the other hand, the "protection range" and "warning range" can be set by the user. The "protection range" can only be set within the "maximum protection range." However, the "warning range" can be set within the "measuring range."

[0020] With reference to Fig. 2, the maximum protection range of the optical scanning photoelectric switch 1 to which the present invention has been applied is a range having a radial distance (extension) of about 4 m, and as described above, the “protection range” can be set by the user with the restriction to the inside of this maximum protection range having the radial distance of about 4 m.

[0021] The "protection area" corresponds to a safety output for stopping the start-up or operation of a machine (e.g., a robot), and when, for example, an operator enters this "protection area", the photoelectric optical scanning switch 1 of the machine sends a safety output indicating the prohibition of operation, that is, an OFF state output.

[0022] The "warning area" does not correspond to the safety output, but corresponds to a non-safety output (normal output) that issues an alarm about approaching the machine. Furthermore, the scanning angle of the photoelectric optical scanning switch 1 is 270° at most, and the protection area and the warning area can be set to an area behind the photoelectric optical scanning switch 1.

[0023] In the example of Fig. 2, an operating area of ​​a robot 2 and an area equipped with a conveyor device are separated by a protective fence 3, and an area adjacent to the operating area of ​​the robot 2, in the area defined by this protective fence 3, is defined as protective area A. The photoelectric optical scanning switch 1 is installed to observe this protective area A. If, for example, an operator M enters the protective area A, the entry is immediately sensed by the photoelectric optical scanning switch 1. It should be noted that for the Fig. 2, a protection area A (low) with a relatively low detection capability and a protection area A (high) with a relatively high detection capability are provided. These two types of protection areas have different detection capabilities, and the protection area A (low) and the protection area A (high) are effective when the photoelectric optical scanning switch 1 is provided with a plurality of output systems, which will be described later.

[0024] Fig. 3 is a view for explaining a basic structure of an optical system of the photoelectric optical scanning switch 1. Referring to Fig. 3, elements of the optical system of the photoelectric optical scanning switch 1 are described. Beam path:

[0025] The photoelectric optical scanning switch 1 performs detection using laser light having a wavelength in the infrared range. The photoelectric optical scanning switch 1 scans a horizontal surface with laser light at a predetermined pitch and receives the reflected light to detect the entry of a person or object M. Light emission device:

[0026] In Fig. 3, reference symbol LD denotes a light projection element. The laser light L1 emitted from the light projection element LD passes through a light projection lens 10, is polarized by first and second light projection mirrors (reflection mirrors) 11, 12, and travels downward in a direction along a predetermined first vertical axis line Z. Therefore, the light projection lens 10 and the first and second light projection mirrors 11, 12 constitute a light irradiation device for irradiating the laser light L1 along the first vertical axis line Z. The light projection element LD emits the laser light L1 in pulse form intermittently at a fixed time period, and this laser light is emitted from the light projection element LD every 0.36°.It should be noted that, as those skilled in the art will understand from the following description, the theoretical basis for detection (sensing) by the photoelectric optical scanning switch 1 does not utilize laser light-specific properties such as light coherence. Therefore, it goes without saying that a laser light source as the light projection source of the photoelectric optical scanning switch 1 is merely an example, and the light source is not limited to this laser light; rather, a variety of light sources can be used. Incidentally, a laser diode is a point light source with high luminance and excellent, very fast response characteristics for the timing of light pulse emission. Therefore, the laser diode can be the preferred light source for the photoelectric optical scanning switch 1. Optical scanning device 14:

[0027] The laser light L1 polarized by the second mirror 12 for light projection in the direction along the first vertical axis line Z travels to an optical scanning device 14 arranged below the second mirror 12. The optical scanning device 14 is composed of a scanning mirror arranged in a state in which it is inclined at substantially 45° from the first vertical axis line Z. This scanning mirror 14 is rotationally driven with the first vertical axis line Z as the center. The optical scanning device (scanning mirror) 14 is driven by a motor 24 ( Fig. 7) driven to rotate (in Fig. 3 not shown). As indicated by the dotted lines in Fig. 4B, the laser light L1 scans the horizontal surface orthogonal to the first vertical axis line Z by means of a rotational operation of the scanning mirror 14, with the first vertical axis line Z being the center. Fig. Reference symbol A shown in Fig. 4B denotes an exemplary set “protection area” and reference symbol B denotes a “maximum protection area”.

[0028] It should be noted that although the scanning mirror 14 is composed of a mirror rotating around an axis, which is used for both light projection and light reception in the illustrated example, as a modification of the example, a configuration may be adopted in which the light projection and light reception are performed by individual scanning mirrors, wherein the scanning mirror for light projection and the scanning mirror for light reception are arranged on the same axis and are also arranged to face in the same direction, and then rotated synchronously. Received light reflecting body 21, photoelectric conversion element 22:

[0029] When the object M is located in the warning area or the protection area A, light L2 reflected by this object M is input into the photoelectric optical scanning switch 1, and this reflected light L2 is reflected by the scanning mirror 14 and then collected by a light receiving lens 20 ( Fig. 3). The light-receiving lens 20 has an optical axis coincident with the first vertical axis line Z, and the reflected light L2 collected by the light-receiving lens 20 is polarized by a reflected light reflecting body 21 and collected in a photoelectric conversion element 22 as a light-receiving element.

[0030] Still referring to Fig. 3, the received light reflecting body 21 is arranged to be inclined by substantially 45° from the first vertical axis line Z, and the optical axis of the reflected light L2 collected by the light receiving lens 20 is polarized by this received light reflecting body 21 in a direction along a second axis line Y in a lateral direction substantially perpendicular to the first vertical axis line Z, and the reflected light L2 after this polarization is received by the photoelectric conversion element 22. Upon receiving the reflected light L2, the photoelectric conversion element 22 performs photoelectric conversion to generate a light reception signal.

[0031] With reference to Fig. 4A, the photoelectric optical scanning switch 1 has a control device 30 which is composed of a CPU, a microcomputer with memory, an FPGA (field programmable gate array) and the like. Fig. Figure 4A shows an overall system of the photoelectric optical scanning switch 1 as a block diagram. The light projection element LD is controlled by the control device 30, and a signal from the photoelectric conversion element 22 is input to the control device 30. External configuration of the photoelectric optical scanning switch 1:

[0032] With reference to Fig. 5, the photoelectric optical scanning switch 1 has a user interface section 32 arranged at an angle to the front surface of the upper end of the switch. With the inclined user interface section 32, the area of ​​the user interface section 32 can be expanded and thus becomes more accessible to the user.

[0033] In the inclined user interface section 32, a rectangular liquid crystal display section 34 is provided at the center, and a plurality of push buttons 36 for operation are arranged on one side and below the liquid crystal display section 34. Further, on the other side of the liquid crystal display section 34, a plurality of LED indicators 38 are arranged vertically separated and arranged in two lateral columns, and an operating state of the photoelectric switch to optical scanning 1 is displayed by these plurality of LED indicators 38.

[0034] In Fig. 6B, the user interface section 32 is extracted and illustrated two-dimensionally. On the right side of the liquid crystal display section 34, when viewed from a position facing the user interface section 32, buttons 36a and 36b are arranged, each marked with an "up arrow" and a "down arrow." Below the liquid crystal display section 34, a button 36d marked with the letters "Esc" is arranged on the left side, and a button 36e marked with the letters "Enter" is arranged on the right side, sandwiching a central button 36c marked with a right arrow.

[0035] By tilting the user interface section 32 to expand its area, a relatively large liquid crystal display section 34 can be arranged. Furthermore, the plurality of operation buttons 36 can be accommodated in the user interface section 32, and with this operation button 36 installed on the photoelectric optical scanning switch 1, a design can be achieved in which the setting operation of a setting required by the user can be performed directly on the photoelectric optical scanning switch 1 without an external personal computer as a terminal with a display.Here, the liquid crystal display section 34 can display twelve characters in four lines, and the information necessary for the user is provided by means of the liquid crystal display section 34, which is capable of displaying a relatively large amount of information as described, thereby allowing the user to perform the necessary setting operation merely by operating the operation buttons 36 and viewing the liquid crystal display section 34 without an external personal computer.

[0036] Particularly in the case of setting a directly safety-related function, such as setting the "protection area," it is necessary for the user to confirm whether the setting has been performed correctly. The setting of the directly safety-related function, i.e., the "protection area" setting in this case, is reflected only after the user completes a verification operation. The user verification operation is performed in the following method. The optical scanning photoelectric switch 1 is designed so that, after a setting is input, the content of the setting that was input by the user and has not been reflected is displayed on the liquid crystal display section 34 using letters, numbers, symbols, and the like.While, as described above, the user is required to check whether the content displayed on the liquid crystal display section 34 matches the content to be set, it is designed to prompt the user to issue an OK instruction, followed by pressing the operation button 36 when the user determines the match. The photoelectric optical scanning switch 1 then completes the checking of the content displayed in the liquid crystal display section 34 by receiving the OK instruction. If there is any unverified content, the photoelectric optical scanning switch 1 displays the content in the liquid crystal display section 34 and waits for an OK instruction from the user. The photoelectric optical scanning switch 1 completes the checking operation state by receiving OK instructions regarding all the contents and reflects those contents whose checking operations have been completed as settings.On the other hand, if the user determines that the contents displayed on the liquid crystal display section 34 do not match the contents to be set, the user can cancel using the operation button 36. By accepting the cancel instruction, the photoelectric optical scanning switch 1 completes the verification process without reflecting all the input contents in the settings and then enters the state for accepting a setting input.However, checking input contents with respect to a position and an area of ​​the protection area A and the like based only on checking a correspondence of displayed contents is not sufficient, and therefore, in practice, the user performs a checking operation of the input contents with respect to the position and the area of ​​the protection area A and the like by holding a test piece at a location corresponding to a position and an area to be set by the user after checking a distance measuring function including the optical system of the photoelectric optical scanning switch 1.It is therefore preferable to display in the liquid crystal display section 34 not only an image for accepting the setting of the directly security-related function but also an image for the user to check the set contents and to perform the previous check by the user with this check screen.

[0037] Fig. Fig. 6A is a front view of the photoelectric optical scanning switch 1, wherein a horizontal surface scanned with laser light, ie, a scanning surface 39, is indicated by a transverse line. As can be seen from the Fig. 7, which illustrates an internal configuration of the photoelectric optical scanning switch 1, the photoelectric optical scanning switch 1 has a device body 60 ( Fig. 9), which is formed by modularized mechanical components such as the optical scanning device (scanning mirror) 14 and the motor 24 necessary for its drive, and the motor 24 is arranged at the bottom of the device body 60. A photoelectric encoder 25, for example, is provided on the rotation axis of the rotor 24. The photoelectric encoder 25 has a plurality of slits equally spaced in a circumferential direction, and based on an output depending on the light passing through these slits, a rotation angle of the optical scanning mirror 14 is calculated to obtain the polarization directions of the projected / received light L1, L2.

[0038] Back in Fig. 4A, the control device 30 is connected to the liquid crystal display section 34, the LED indicators 38, and the operation buttons 36. Further, the control device 30 is connected to a first connector 40, and this first connector 40 can be connected to a connector 44 of an external cable 42 extending from external devices.

[0039] The control device 30 is provided with a distance calculation device 51, a direction calculation device 52, a position detection device 53, a discrimination device 54, an impurity measurement device 55, a signal generation device 56, a display control device 57, an error measurement device 58, and the like. Distance calculation device 51:

[0040] The distance calculation device 51 calculates a distance to the object M based on the light reception signal from the photoelectric conversion element 22 in each polarization direction. That is, a distance to the object M can be calculated by multiplying a difference between the light projection time of the scanning light L1 from the light projection element LD and the light reception time of the photoelectric conversion element 22 that receives the light L2 reflected from the object M by the known speed of light. The light projection time is a predetermined period of time, and the generation of this light projection time and an angular velocity of the motor 24 define a spatial density of the optical axes, that is, an angle between the optical axes. Note that the light projection time can be defined as "time," or it can be defined as "direction" or "spatial density (angle between optical axes)."The calculation of the distance based on the light projection / reception time may be performed once every predetermined time minute or may be performed, for example, at each light projection / reception synchronously with the light projection time. Direction calculation device 52:

[0041] The direction calculation device 52 calculates, during light projection and reception, an emission direction (polarized direction) of the scanning light L1 polarized by the optical scanning device 14 toward the measurement area, as well as an incidence direction of the light L2 reflected from the object M. However, since the travel time of the light to and from the object M in the "measurement area" is comparatively sufficiently short with respect to the angular velocity of the motor 24, and the emission direction and the incidence direction can thus be considered identical, both the emission direction and the incidence direction can be calculated. This polarized direction of the projected / received light L1, L2, i.e., the direction of the scanning surface (scanning direction), can be obtained by calculating the rotation angle of the optical scanning device 14 based on the previous output from the rotary encoder 25.It should be noted that when defining the light projection time as a direction or spatial density (angle between optical axes), the polarization direction (scanning direction) is preferably defined as the radiation direction. Furthermore, this direction is equivalent to a number of an optical axis. Position detection device 53:

[0042] The position detecting device 53 detects a position of the object MD, i.e., the position detecting device 53 calculates the position of the object M based on the polarization direction (scanning direction) calculated by the direction calculating device 52 at each light projection / reception time and the distance to the object M calculated by the distance calculating device 51 in this polarization direction, so as to detect the position of this object M. Distinguishing device 54:

[0043] The discrimination device 54 discriminates whether or not the object M is located in the previously set protection area A based on the position of the object M calculated by the position detection device 53. In addition, the discrimination device 54 may be configured to provide "presence" indicating information when examining the presence of the object M in the protection area itself only once (in one period) or to provide the "presence" indicating information only after examining the presence of the object M in the protection area over a plurality of periods.

[0044] The optical system of the photoelectric optical scanning switch 1 is sealed by a light-transmitting cover 62 with a U-shaped lateral cross section, which surrounds the front surface and the two side surfaces of the lower half of the photoelectric optical scanning switch 1, and this light-transmitting cover 62 forms a light-shielding window. Fig. Fig. 8 illustrates a state in which the light-transmitting cover 62 has been removed. The light-transmitting cover 62 is fixed via a sealing member 64 and can be removed from the photoelectric optical scanning switch 1 by a plurality of bolts 66 ( Fig. 5). The light-transmitting cover 62 of the light-shielding window is an optical filter and removes wavelength components except those of the laser light emitted from the optical scanning photoelectric switch 1. Although the light-transmitting cover 62 is made of any material, here it is made of an elastically deformable resin material.

[0045] How best to Fig. As shown in Fig. 7, a sectional view of the device body 60, the optical scanning device (scanning mirror) 14 is arranged at the front end and away from the rear surface portion at the bottom of the device body 60, and thereby the first vertical axis line Z as the rotational axis line of the scanning mirror 14 is positioned relatively offset forward. On the other hand, the light-transmitting cover 62 surrounds the front and lateral sides of the device body 60, and both the right and left ends of this light-transmitting cover 62 extend to the rear surface of the photoelectric optical scanning switch 1. By selecting such a configuration, it is possible to design the right and left areas and the front area of ​​the photoelectric optical scanning switch 1, excluding a portion interfering with the rear surface, as the scanning area (measurement area).The same applies to the case where the scanning mirror for light projection and the scanning mirror for light reception, which rotate mutually synchronously, are arranged on the same axis and are arranged to face in the same direction, as previously described in the modified example of the scanning mirror 14.

[0046] In this regard, as described above, the scanning range (measuring range) of the photoelectric optical scanning switch 1 is 270°, having been expanded backward from 180°. The scanning range of the photoelectric optical scanning switch 1 can be extended backward in this way, essentially by combining two configurations: (1) a configuration is selected in which on the scanning surface 39 ( Fig. 6A) the width of the rear surface of the photoelectric optical scanning switch 1, which interferes with the scanning surface 39, is restricted to a range of 90°; and further (2) the first axis line Z as the rotation axis of the scanning mirror 14 is spaced from the rear surface of the photoelectric optical scanning switch 1, and the two mutually parallel side surfaces of the U-shaped cross-sectional light-transmitting cover 62 are extended rearward so that the entire area of ​​the sides and the front area of ​​the photoelectric optical scanning switch 1, except for the rear surface, are surrounded by the light-transmitting cover 62.In other words, the photoelectric optical scanning switch 1 is thin and has a small height compared to a conventional article, has a volume approximately half that of the conventional article, and has a size such that it is capable of being easily placed on a palm.

[0047] The shape of the translucent cover 62, ie a gradually expanding shape ( Fig. 5, Fig. 8), should also be noted. How best to proceed from the Fig. As can be seen in Figure 5, a lower portion 62a of the translucent cover 62 is configured as a vertical wall, and a portion gradually extending outward toward the tip has an overhanging shape. In this vertical intermediate portion of this overhanging portion 62b, the horizontal scanning surface 39 is defined ( Fig. 6).

[0048] It should be noted that, as best seen Fig. 5, a portion in contact with the underside of the translucent cover 62 is configured as a horizontal step portion 70 projecting outward. First and second optical elements 71, 72 are arranged so that the translucent cover 62 is located therebetween ( Fig. 4), and the second optical element 72 located outside the light-transmitting cover 62 is arranged on the horizontal step portion 70. In other words, the first optical element 71 is arranged inside the light-transmitting cover 62, and this first optical element 71 is installed downward (toward the second optical element 72). That is, the first and second optical elements 71, 72 are positioned opposite each other in pairs, and a plurality of pairs of first and second optical elements 71, 72 are provided at the edge of the light-transmitting cover 62 at an appropriate distance. First and second optical element 71, 72:

[0049] The transparent cover 62 of the optical scanning photoelectric switch 1 serves as a filter for blocking visible light. Naturally, a material was selected that allows the scanning light L1 and the reflected light L2 to pass through. When this transparent cover 62 becomes dirty or ages over time, its transmittance decreases, causing a decrease in the amount of reflected light L2 incident on the photoelectric conversion element 22. Needless to say, this phenomenon is undesirable because it causes a deterioration in the sensitivity for detecting a position of the object M.

[0050] Each pair of first and second optical elements 71, 72, which are opposite to each other and between which the light-transmitting cover 62 is located, continuously monitors the contamination state of the light-transmitting cover 62. Light emitted from the first optical element 71 enters the second optical element 72 through the light-transmitting cover 62, and the amount of this light received by the second optical element 72 is supplied to the control device 30. Contamination measuring device 55:

[0051] Using the amount of light received by the second optical element 72, the contamination measuring device 55 checks whether the translucent cover 62 maintains a predetermined transmittance. A decrease in transmittance due to aging of the translucent cover 62 constituting the light-shielding window, its contamination, or the like, can be measured based on the amount of light received by the second optical element 72. Here, if the amount of light received by the second optical element 72 is not greater than a predetermined threshold, the user can be notified via the liquid crystal display section 34 or the LED display 38 that it is time to replace the translucent cover 62. Furthermore, the contamination measuring device 55 represents a fault detection device for determining whether the photoelectric optical scanning switch 1 is functioning or not, i.e.,a device for checking whether the photoelectric optical scanning switch 1 is in such a safe state that it is capable of performing an intended detection or the like, and when the contamination measuring device 55 determines that the photoelectric optical scanning switch 1 is out of operation, the user is warned by means of the liquid crystal display section 34 or the LED display 38, while an operation-disallowing signal is transmitted to the external equipment by the signal generating device 56.

[0052] It should be noted that although an example has been described in which first and second optical elements 71, 72 are arranged opposite each other with the light-transmitting cover 62 therebetween to detect contamination and aging of the light-transmitting cover 62, a reflection mirror may be arranged on the horizontal step portion 70 instead of the second optical element 72, light emitted from the first optical element 71 may be reflected by the reflection mirror, and the reflected light may be received by the second optical element 72 arranged adjacent to the first optical element 71. According to this example, the first and second optical elements 71, 72 are arranged adjacent to each other within the light-transmitting cover. Signal generating device 56:

[0053] The signal generating device 56 generates a safety signal based on the result of discrimination by the discriminating device 54. For example, when a normal operation of the optical scanning photoelectric switch 1 is verified in a predetermined mode and the discriminating device 54 determines that the object M is not located in the protection area A, the signal generating device 56 generates an ON signal (operation permitting signal) as a safety output, and this safety output is transmitted to the external equipment via the control device 30 and the first connector 40 through the external cable 42, so that the operation of the external equipment is permitted.

[0054] The error measuring device 58 is used to check that the photoelectric optical scanning switch 1 is operating correctly, and if the normal operation cannot be verified, the photoelectric optical scanning switch 1 is regarded as out of operation. Adjustment mechanism for maintaining the measurement sensitivity of the photoelectric optical scanning switch 1:

[0055] Fig. 9 and Fig. 10 each shows a state in which the optical scanning means, i.e., the scanning mirror 14, faces the back side of the photoelectric optical scanning switch 1. It goes without saying that, in this state, detection by the photoelectric optical scanning switch 1 is impossible. In a rising column portion 60a of the device body 60, two reflection surfaces, the first and second reflection surfaces 73, 74, as reference objects are arranged at positions where these reflection surfaces can face the scanning mirror 14 on the trailing side and the leading side, respectively, in the rotation direction of the scanning mirror 14, i.e., right and left, and these first and second reflection surfaces 73, 74 are arranged in a state of facing obliquely upward while being inclined at approximately 45°.Further, in the column portion 60a, a fixed mirror 75 is disposed opposite the first and second reflecting surfaces 73, 74, inclined downward at approximately 45°. That is, in the ascending column portion 60a of the device body 60, the first and second reflecting surfaces 73, 74 are disposed obliquely upward at positions that the scanning mirror 14 faces when rotating backward, and the fixed mirror 75 is disposed above the first and second reflecting surfaces 73, 74, obliquely downward.

[0056] The first and second reflection surfaces 73, 74 as reference objects are made of materials with different reflection factors and have colors with different reflection factors. As a specific example, the first reflection surface 73 is made of a black or black-colored material, and the second reflection surface 74 is made of a white or white-colored material.

[0057] The laser light pulse L1 emitted by the light projection element LD is incident on the scanning mirror 14 via the light projection lens 10 and the first and second mirrors (reflection mirrors) 11, 12 for light projection. The scanning mirror 14 converts this light into light traveling in a horizontal direction. When the scanning mirror 14 is facing forward or sideways, this laser light pulse L1 is guided to the measurement area. Even if the scanning mirror rotates backward, in the middle of its 360° rotation, the laser light pulse L1 is first guided to the first black reflection surface 73 by the rearward-facing scanning mirror 14, and then to the white second reflection surface 74.This laser light pulse L1 is reflected by the first and second reflecting surfaces 73, 74, which are inclined upward, and travels upward in the vertical direction (L3), and this reflected light pulse L3 is reflected by the fixed mirror 75 located above the first and second reflecting surfaces 73, 74. Since this fixed mirror 75 is arranged in a downwardly inclined posture of approximately 45°, the light pulse L3 reflected by the fixed mirror 75 returns to the scanning mirror 14, is reflected by this scanning mirror 14, and travels upward to be collected by the light-receiving lens 20 and the received light reflecting body 21 by means of the photoelectric conversion element 22. That is,that the light pulse L3 reflected by the first and second reflection surfaces 73, 74, respectively, is input to the photoelectric conversion element 22 as a light receiving element through the same elements 14, 20, 21 as in the case of the light L2 reflected by the object M in the warning area or the protection area A.

[0058] Behind the scanning mirror 14, the first reflection surface 73 (black) and the second reflection surface 74 (white) having different reflection factors are provided side by side on the trailing and leading sides in the rotation direction (scanning direction) of the scanning mirror 14, and the fixed mirror 75 is also provided fixedly to the column portion 60a, whereby the reflected light pulse L3 reflected from each of the first reflection surface (black) 73 and the second reflection surface (white) 74 is input into the photoelectric conversion element 22 through the same elements 14, 20, 21 as in the case of the light L2 reflected from the object M in the warning area or the protection area A.

[0059] Besides, the light reception intensity at the time of irradiating the reference object with laser light pulses and at the time of receiving the reflected light pulses can be expressed by the following formula: Light reception intensity = {light projection intensity × optical property of the light projection path × reflection factor of the reference object ÷ (distance to the reference object) 2 × optical property of the light reception path × light reception gain}

[0060] Furthermore, in the case of scanning with laser light, the detection sensitivity can be expressed by the following formula without having to resort to the reflection factor of the object and the distance to the object: Detection sensitivity = {light projection intensity × optical property of the light projection path × optical property of the light reception path × light reception gain}

[0061] According to the above formulas 1 and 2, the following formula 3 is established when the reflection factor of the reference object and the distance to the reference object are constant: Detection sensitivity={light reception intensity×fixed value}

[0062] Since the integration of the reference object into the photoelectric switch for optical scanning 1 using laser light facilitates the constant reflection factor of the reference object and the distance to the reference object, maintaining a constant light reception sensitivity, which was obtained by projecting light onto the reference object, allows the detection sensitivity to be kept constant. From this point of view, for example,When the photoelectric optical scanning switch 1 is shipped from the factory, the light receiving intensity of the photoelectric optical scanning switch 1 is measured when its detection sensitivity is in an optimal state, which is then stored in a memory element of the photoelectric optical scanning switch 1, and when the photoelectric optical scanning switch 1 is in operation, a light projection intensity and / or a light receiving gain is adjusted so that the light receiving intensity becomes the light receiving intensity stored in the memory element, whereby it is possible to keep the detection sensitivity of the photoelectric optical scanning switch 1 in the optimal state.

[0063] Fig. 11 is a view in which the first and second reflection surfaces 73, 74 are shown separately, and an arrow indicates the rotation direction, that is, the scanning direction of the scanning mirror 14. Fig. Fig. 12 illustrates a state where a laser light pulse is incident on the first and second reflection surfaces 73, 74 in a time sequence.

[0064] It is assumed that the light reception intensity is “100” when the laser light pulse hits the black reflection surface 73 as one of the reference objects ( Fig. 12(I)), and the light receiving intensity is “600” when the laser light pulse hits the white reflection surface 74 as the other reference object ( Fig. 12(II)). Although the terms "black" and "white" are used herein with reference to the first and second reflection surfaces 73, 74, they should be understood as terms for convenience. "Black" means a low reflection factor with respect to a wavelength of the laser light as the light projection source, and "white" means a high reflection factor with respect to the wavelength of the laser light as the light projection source. Furthermore, since the use of a surface with a sufficiently low reflection factor as the black reflection surface 73 makes the reflection factor of a contaminating material equivalent to or not smaller than the reflection factor of the black reflection surface 73, the black reflection surface 73 tends to have an increased reflection factor when contaminated.On the other hand, the use of a surface with a sufficiently high reflection factor as the white reflection surface 74 results in the second reflection surface 74 having a lower reflection factor when dirty.

[0065] In the case of adjusting the light projection intensity and / or the light reception gain such that the light reception intensity on the white second reflection surface 74 is "600", adjustment of the light projection intensity and / or the light reception gain is performed when the white second reflection surface 74 is contaminated and its reflection factor thus decreases, so as to maintain the light reception intensity on the second reflection surface 74 at "600". In this case, the light reception intensity on the first reflection surface 73 increases due to an increase in the light reception intensity, with the reflection factor and the distance remaining constant. In order to handle this phenomenon, the light reception intensities of the first and second reflection surfaces 73, 74 are continuously monitored, an allowable range (e.g.80 to 120) is set as the value of the light receiving intensity on the first black reflection surface 73, and when the light receiving intensity on the first black reflection surface 73 exceeds the allowable range, it is assumed that contamination has been generated on the white second reflection surface 74. When contamination has been generated on the white second reflection surface 74, appropriate sensitivity adjustment becomes impossible, thus preventing accurate observation of the protection area A, and therefore the optical scanning photoelectric switch 1 brings the safety output to an OFF state to stop the power supply to a danger source.Further, the optical scanning photoelectric switch 1 can be configured to notify the user that safety cannot be verified (the safety output is in the OFF state) and also to display the reasons why safety cannot be verified (error content) using the liquid crystal display section 34 or the LED display 38. In addition, the optical scanning photoelectric switch 1 can be configured to output the occurrence of an error using a non-safety output signal different from the safety output, or to transmit an error factor and the safety output being in the OFF state to an external personal computer PC through a communication cable 80.

[0066] Similarly, when the reflection factor increases due to contamination on the first black reflection surface 73, the reflected light on the first reflection surface 73 is intensified, and the phenomenon of an increase in the light reception intensity on the first black reflection surface 73 thus occurs. When the light reception intensity exceeds the allowable range on the first black reflection surface 73, this time too, it is assumed that contamination has been generated on the black first reflection surface 73 as one of the reference objects, and an alarm can be output to the user using the liquid crystal display section 34 or the LED display 38.

[0067] By incorporating the first and second reflection surfaces 73, 74 with different reflection factors as reference objects into the photoelectric optical scanning switch 1 and sharing the optical system of the photoelectric optical scanning switch 1, it is possible to continuously observe the light reception intensity and adjust the light projection intensity and / or the light reception gain to make the light reception intensity constant. Therefore, when designing the photoelectric optical scanning switch 1, it is not necessary to anticipate age-related deterioration and changes in ambient temperatures during operation, and to consider these changes as within the allowable range and define a large tolerance as the specification.Furthermore, it is possible to establish a predetermined detection sensitivity by making the tolerance limit low and initially setting the light projection intensity and / or the light reception gain high, thereby facilitating the size reduction of the optical scanning photoelectric switch 1. In addition, since it is configured so that contamination of the adjusting device consisting of the first and second reflecting surfaces 73, 74 is detected as a failure, it is possible to determine a tolerance limit for the detection performance to ensure safety, thus providing a photoelectric optical scanning switch 1 capable of performing long-range detection beyond ensuring safety despite its small size. Setting the protection area A:

[0068] The setting of the protection area A by the photoelectric optical scanning switch 1 is carried out using the personal computer PC, regardless of whether it is set up to allow the photoelectric optical scanning switch 1 to perform only a simple setting as shown in Fig. 13. The personal computer PC and the photoelectric optical scanning switch 1 are mutually connected by the communication cable 80. As is known, the personal computer PC has a display 81 and an input operation section 82.

[0069] The personal computer PC has installed thereon an application program for initially setting the protection area A, and by using this program, the protection area A of the photoelectric optical scanning switch 1 can be edited.

[0070] Fig. 14 is a block diagram illustrating a configuration of the personal computer PC as a system for editing a protection area. The personal computer PC is provided by the application program with functions of a section 84 for specifying added / removed areas, a section 86 for extracting an incorrectly adjusted area, a section 87 for refreshing the set area, a section 88 for saving the set area, a section 89 for transmitting the set area, and a dialog display section 90.

[0071] The set area storage section 88 is a memory that stores the set area information for specifying the protection area A to the optical scanning photoelectric switch 1. The added / removed area specifying section 84 performs an operation of specifying an added area, a removed area, and a line segment based on an input signal from the input operation section 82.

[0072] In the case of adding an area to the protection area already set in the photoelectric optical scanning switch 1, a user-designated area is designated as the added area. Furthermore, in the case of removing an area from the already set protection area A, a user-designated area is designated as the removed area.

[0073] The misadjusted area extraction section 86 performs the process of automatically extracting, as a discrepancy area, an area located between the protection area A and the added area as viewed from the optical scanning photoelectric switch 1. That is, when an area that cannot be designated as a sensor-detected area exists between the protection area A and the area designated as the added area as viewed from the optical scanning photoelectric switch 1, the process of extracting the above-mentioned area as a discrepancy area is performed.

[0074] In the discrepancy region extraction section 86, when a line segment is specified during region addition, a region located between the protection region A and the line segment—as viewed from the optical scanning photoelectric switch 1—is extracted as a discrepancy region. Here, the discrepancy region extracted during region addition is referred to as an interpolation region.

[0075] Further, the discrepancy region extraction section 86 performs a process of automatically extracting, as a discrepancy region, an area located behind the erased area and within the protection area A as viewed from the optical scanning photoelectric switch 1. That is, when an area designated as the protection area A exists behind the area designated as the erased area as viewed from the optical scanning photoelectric switch 1, the process of extracting the above area as a discrepancy region is performed.

[0076] In the discrepancy region extraction section 86, when a line segment is specified during region removal, a region located behind the line segment and within the protection region A as viewed from the optical scanning photoelectric switch 1 is extracted as a discrepancy region. Here, the discrepancy region extracted during region removal is referred to as a "shadow region."

[0077] The area display section 85 controls the display 81 and performs the process of visually identifiably displaying the protection area A, the added area, the removed area, and discrepancy areas (the interpolation area and the shadow area) based on set area information stored in the set area storage section 88. That is, in the case of adding an area to the already set protection area A, the interpolation area is identifiably displayed with respect to the protection area A and the added area, and at this time, the interpolation area is identifiably displayed with respect to the protection area A before the addition of the added area and the interpolation area is performed on the display 81.

[0078] Further, in the case of deleting an area from the already set protection area, the shadow area is identifiably displayed with respect to the protection area A and the deleted area, and at this time, the shadow area is identifiably displayed with respect to the protection area A before the deletion of the deleted area and the shadow area on the display 81.

[0079] The set area updating section 87 performs the process of updating the protection area A stored in the set area storage section 88 based on an input signal from the input operation section 82. That is, in the case of adding an area to the already set protection area A, the protection area is updated with the added area and the interpolation area as the new protection area A.

[0080] When the line segment is specified during the addition of an area, the information about the set area is updated so that the protection area A with the added interpolation area becomes the new protection area A.

[0081] Furthermore, in the case of deletion of an area from the already set protection area A, the information about the set area is updated so that the protection area A with the area deleted from it and the shadow area deleted from it is set as the new protection area A.

[0082] If the line segment is specified during the deletion of an area, the information about the set area is updated so that the protection area A with the shadow area deleted from it becomes the new protection area A.

[0083] The dialog display section 90 controls the display 81 and displays a check dialog based on an input signal from the input operation section 82. That is, in the case of adding an area to the already set protection area A, a question dialog 93 is displayed as a check dialog on the screen 81 to ask whether or not to add the added area and the interpolation area to the protection area A.

[0084] Similarly, in the case of deleting an area from the already set protection area A, a question dialog 93 is displayed as a review dialog on the screen 81 to ask whether the deleted area and the shadow area should be deleted from the protection area A or not.

[0085] In the set area updating section 87, based on an input signal from the input operation section 82 after display of the above question dialog, that is, an operational input about a change of permission by the user, the set area information is updated in the set area storage section 88.

[0086] The set area transmission section 89 performs the operation of transmitting information about the protection area A stored in the set area storage section 88 to the photoelectric optical scanning switch 1. Further, such a configuration is adopted for the set area transmission section 89 in which, after transmitting information about the protection area A to the photoelectric optical scanning switch 1, a return of the information about the protection area A is accepted from the photoelectric optical scanning switch 1 before the transmitted protection area A is reflected to the photoelectric optical scanning switch 1, so that the returned information can be used for the operation of checking the protection area A performed by the user.A reflection of the transmitted protection area A to the photoelectric optical scanning switch 1 is performed after the operation of checking the protection area A by the user.

[0087] Fig. Figure 15 shows the area setting screen displayed on the display 81 of the personal computer PC. This area setting screen is an input screen for redefining the protection area A or for changing an already set protection area A.

[0088] In the range setting screen displayed on the display 81, a maximum detection range (measurement range) is displayed with respect to an orthogonal coordinate, wherein a symbol S shows the photoelectric optical scanning switch 1 at the center, and grid lines G1 parallel to an abscissa axis are arranged at a pitch of 500 mm, while grid lines G2 parallel to an ordinate axis are arranged at a pitch of 500 mm.

[0089] Behind the symbol S, the upper limit of the measurable distance changes based on the emission angle of the scanning laser light, and the sensor-detectable angular interval is not less than -45° and not less than +225°. An area in an interval other than this angular interval H is called a blind interval and cannot be designated as a protection area A.

[0090] Fig. 16 shows a screen in the case of adding an area 92 to a rectangular protection area A. Apart from the rectangular shape, the protection area A may also have a polygonal shape, a circular shape in which the symbol S shows the photoelectric optical scanning switch 1 in the center, a sector shape or the like, and a closed area in which a line drawn by moving a mouse pointer is taken as a boundary may also be designated as the protection area A.

[0091] Assuming that the protection area A has been designated in the area setting screen displayed on the display 81, for example, when a decision key has been pressed by the user, the protection area A is designated, and an area that must be added at least to make this protection area A an object to be detected is automatically extracted as an interpolation area 92. That is, from the viewpoint of the optical scanning photoelectric switch 1, the interpolation area 92 is extracted as an object not to be detected between the area designated as the protection area A and the optical scanning photoelectric switch 1.A verification dialog 93 asking whether or not to add the interpolation area 92 to the protection area A is displayed, and if the addition is permitted by the user, an area obtained by adding the interpolation area 92 to the protection area A, which has been specified by the user, is set as a new protection area A, and the information is updated based on this new protection area A.

[0092] Fig. 17 shows an example of deleting a part of the protection area A. An area deleted from the protection area A can be arbitrarily designated, and reference numeral 94 denotes a user-designated deleted area. Apart from the rectangular shape, the deleted area can be designated to have a polygonal shape, a circular shape with the optical scanning photoelectric switch 1 as the center, a sector shape, or the like. Furthermore, a closed area using a curved line as a boundary can also be designated, with the curved line drawn while moving a mouse pointer on the screen.

[0093] An area 94 enclosed in the protection area A is designated as the erased area, and when, for example, the decision key is pressed by the user, the erased area 94 is designated as the area to be erased. By erasing this erased area 94 from the protection area A, the erased area 94 is made an undetectable area, so that an area to be erased is automatically extracted at least as a shadow area 95. That is, as viewed from the optical scanning photoelectric switch 1, an area to be detected behind the area 94 designated as the area to be erased is extracted as a shadow area 95.

[0094] When the shadow area 95 is automatically extracted, a verification dialog 93 is displayed, asking whether or not to delete the shadow area 95 from the protection area A. If a change in the protection area including the shadow area 95 is then permitted by the user, an area obtained by deleting the deleted area 94 and the shadow area 95 from the protection area A is set as a new protection area A, and the zone information of this new protection area A is updated. Fig. 17(c) shows the new protection area A. Suppression function (muting function) and switching of the suppression area (muting area):

[0095] The optical scanning photoelectric switch 1 has a muting function that defines a single or multiple muting areas in part or all of the protection area A, and disables a predetermined detection function in the muting area when a predetermined condition occurs. The case of setting a part of the protection area A as the muting area is called "partial muting," and the case of setting the entire protection area A as the muting area is called "complete muting." The optical scanning photoelectric switch 1 is capable of switching to another muting area using additional detection devices or timing sequences.In the following description, switching control of the suppression area (muting area) is described with emphasis on partial suppression, but one suppression area from a plurality of suppression areas may be set as the entire protection area A (“full suppression”).

[0096] The settings of the suppression function (muting function) and the suppression area (muting area) can be made using the personal computer PC as in the previous setting of the protection area A, and the application program used in the setting of the protection area A has been provided with a suppression function.

[0097] Fig. Figure 18 illustrates, by way of example, the case of setting a sector-shaped protection area A using the application program installed on the personal computer PC. This method for setting the protection area A proceeds as described in the previous description with reference to Fig. 13 to 17, and a query dialog 93 asking whether the specific protection area A should be set is displayed on the display 81 as a verification dialog. The designated protection area A is set by user permission using this query dialog 93.

[0098] Fig. Figure 19 shows a display screen for setting the suppression area using the suppression setting function in the application program used for setting the protection area A. Reference numeral 97 denotes an area designated by the user as the suppression area. It should be noted that, as shown in Fig. 19, has defined a rectangular area over an area remote from the photoelectric optical scanning switch with symbol S from the protection area A. In this example, the Fig. 19, this specific area 97 includes at least the end of the protection area A remote from the photoelectric optical scanning switch with symbol S. If the end remote from the symbol S is not included, ie if the area in the protection area A is in a vertically central section of the Fig. 19, a shadow area described later is automatically extracted, and this shadow area is displayed. The user-designated area 97 is displayed superimposed on the protection area A, the protection area A and the user-designated area 97 are displayed with different colors, and the portion where the user-designated area 97 and the protection area A overlap is displayed with a third color as a mixed color of the first color of the protection area A and the second color of the user-designated area 97.

[0099] On the display 81 of the personal computer PC, a question dialog 93 asking whether the designated area 97 is correct is displayed as a verification dialog, and by permission of the user, a suppression area 98 is set in an area where the designated area 97 and the protection area A overlap ( Fig. 20). When the suppression area is set, the part of the previous area 97 ( Fig. 18), it protrudes from the protection area A, is deleted, and the protection area A and the suppression area 98 set within this protection area A are displayed in different colors. A plurality of suppression areas 98 can be set in the same protection area A in the same way, and a condition for activating the suppression function, the time when the suppression function is executed, and the like can be set by setting a value for each of the suppression areas 98 in Fig. 21 is used.

[0100] It should be noted that a setting operation for the suppression area 98 is performed similarly to the operation in which a part of the protection area A is deleted. That is, when an area to be suppressed is designated, a shadow area to be added as at least the protection area 98 (an area behind the designated area when viewed from the photoelectric switch for optical scanning 1) is automatically extracted, a verification dialog asking whether or not to add the extracted area as the suppression area 98 is displayed, and the setting of the suppression area 98 and its updating are executed in accordance with the issuing of permission.

[0101] For example, if a plurality of suppression areas 98 are set in the protection area A using the setting screen of the Fig. 21, it is possible to set the timing to start the suppression, the timing to reset the suppression, the time period when the suppression state is permitted, a time difference between a plurality of timer signals, and the like for each of the suppression areas 98.

[0102] A specific example will be described using a conveying system for a workpiece W with reference to Fig. 22 described. Fig. Fig. 22 shows a state of a conveyor device (e.g., a belt conveyor) V in side view, wherein the conveyor device V is provided with a gate 100, the photoelectric optical scanning switch 1 is arranged in the center of an upper crossbar of the gate 100, and the photoelectric optical scanning switch 1 is arranged such that the scanning surface 39 ( Fig. 6) extends downward while being aligned with a vertical surface surrounded by the gate 100. This means that when the gate 100 is opened, a light curtain (detection plane) is formed by the photoelectric optical scanning switch 1 located at the top center of the gate 100.

[0103] In the conveyor device V, muting sensors 101 to 104, consisting of photoelectric sensors or the like, are arranged to meet predetermined conditions. According to the conveying direction of the conveyor device V from the upstream to the downstream side, the first and second muting sensors 101, 102 are arranged here on the near side, that is, the upstream side of the gate 100, and the third and fourth muting sensors 103, 104 are arranged on the downstream side of the gate 100. Entry is prohibited to the area downstream of the gate 100. The first to fourth muting sensors 101 to 104 are each connected to the photoelectric optical scanning switch 1 by cables shown outside the figure.As a modification of the example, output signals of the first and third suppression sensors 101, 103 may be wired as an OR circuit, and the output signals of the second and fourth suppression sensors 102, 104 may be wired as an OR circuit to be connected to the photoelectric optical scanning switch 1. An output signal line of the first and third suppression sensors 101, 103 transmits the information from the photoelectric switch to the optical scanning switch 1 that at least one of the first and third suppression sensors 101, 103 has detected the workpiece W. An output signal line of the second and fourth suppression sensors 102, 104 transmits the information from the photoelectric optical scanning switch 1 that either the second or fourth suppression sensors 102, 104 has detected the workpiece W.When the suppression sensor is turned on by detecting the workpiece W, the output signal of the suppression sensor is short-circuited, allowing the signal to become a wired-OR signal. Connecting wired-OR output signal lines to the photoelectric optical scanning switch 1 can reduce the number of input signal lines of the photoelectric optical scanning switch 1 required for the suppression function from four to two. The following describes the case of the wired-OR circuit as an example.

[0104] A gap between the first suppression sensor 101 and the second suppression sensor 102 is D1. A gap between the second suppression sensor 102 and the fourth suppression sensor 104 is D2. A gap between the first suppression sensor 101 and the third suppression sensor 103 is D3. Further, the moving speed of the workpiece W, that is, the conveying speed of the conveying device V, is V1. The foregoing conditions for setting the first to fourth suppression sensors 101 to 104 are as follows: Ta<{T=D1 / V1} <Tb D2 <Lw D3>Lw

[0105] Here, Ta and Tb are predetermined fixed values, and Lw is the longitudinal length of the workpiece W.

[0106] Condition (1) requires that the time difference between the transition of the first suppression sensor 101 to a detection state due to movement of the workpiece W and the transition of the second suppression sensor 102 to the detection state (T = D1 / V1) be within a predetermined interval. Condition (2) is a condition to prevent the second suppression sensor 102 from entering a non-detection state before the fourth suppression sensor 104 enters the detection state. Condition (3) is a condition to prevent the first suppression sensor 101 from entering a non-detection state before the third suppression sensor 103 enters the detection state.

[0107] By arranging the first and second suppression sensors 101, 102 to satisfy the condition (1), it is possible to distinguish the entry of the workpiece W from the entry of another object from the time difference between the transition of the first suppression sensor 101 to the detection state and the transition of the second suppression sensor 102 to the detection state.

[0108] By arranging the first to fourth suppression sensors 101 to 104 so as to satisfy the condition (2) and the condition (3), it is possible to distinguish the entry of the workpiece W from the entry of another object under the condition that the conveying device V conveys at a constant speed by using the different distances in the conveying direction.

[0109] Fig. 23 is a functional block diagram of the photoelectric optical scanning switch 1. In Fig. 23, reference symbol Tr denotes an external input accepting terminal, which accepts an external input from each of the first to fourth suppression sensors 101 to 104. The optical scanning photoelectric switch 1 is composed of a suppression start determining section 106, a suppression state signal generating section 108, and a suppression completion determining section 110. When an object enters the protection area A, a transition is made from the non-detection state to the detection state, and an OFF signal (operation prohibition signal) is output from the safety output signal control section 111.

[0110] Based on a first entry determination section 112 for determining the entry of an object (object M) into the protection area A including the suppression area, an external input signal as an external input accepted from the first and third suppression sensors 101, 103 through the terminal Tr, and an external input signal as an external input from the second and fourth suppression sensors 102, 104 through the terminal Tr, the suppression start determination section 106 determines the establishment of the following conditions and outputs the establishment of the suppression start conditions to the suppression state signal generation section 108.The conditions for establishing the suppression are that the first entry determination section 112 for determining the entry into the protection area A including the suppression area is in the non-detection state, and that a time difference T1 between the time of transition of the first and third suppression sensors 101, 103 from the non-detection state to the detection state and the time of transition of the second and fourth suppression sensors 102, 104 from the non-detection state to the detection state is within a predetermined interval (an interval satisfying Ta < T1 < Tb).

[0111] Based on a result of the determination by the suppression start determining section 106 and a result of the determination by the suppression completion determining section 110, a suppression state signal generating section 108 performs the process of generating a suppression state signal with respect to the safety output signal controlling section 111 and the suppression completion determining section 110.

[0112] Based on a second entry determination section 114 for determining the entry of the object (object M) into the protection area A without the suppression area, the input signals from the first and third suppression sensors 101, 103, the input signals from the second and fourth suppression sensors 102, 104, and the suppression state signal output from the suppression state signal generation section 108, the suppression completion determination section 110 determines the suppression completion process based on the following conditions and outputs the establishment of the suppression completion state to the suppression state signal generation section 108.The suppression completion condition is that the second entry determination section 114 for determining entry into the protection area A excluding the suppression area transitions from the non-detection state to the detection state, or both the first and third suppression sensors 101, 103 transition to the non-detection state, or both the second and fourth suppression sensors 102, 104 transition to the non-detection state, or a suppression state signal output from the suppression state signal generation section 108 remains in the suppression state for a predetermined time Tc. In addition, a signal from a distance measuring section 116 for measuring the distance to the object (object M) is input to the first and second entry determination sections 112, 114.

[0113] Based on the determination results by the suppression start determining section 106 and the suppression completion determining section 110, the suppression state signal generating section 108 performs the process of generating a suppression state signal to designate the suppression to the safety output signal controlling section 111.

[0114] A safety output signal output from the safety output signal control section 111 is used as a control signal to stop a processing machine within the prohibited area downstream of the gate 100. This safety output signal control section 111 controls a safety output signal based on the result of the determination by the first entry determination section 112 for determining entry into the protection area A including the suppression area, on a result of the determination by the second entry determination section 114 for determining entry into the protection area A excluding the suppression area, and on a suppression state signal output from the suppression state signal generation section 108.Specifically, when the suppression state signal is set to "non-suppression," the safety output signal control section 111 controls the safety output to be OFF when the determination result of the first entry determination section 112 regarding the entry into the protection area A is the detection state, and the safety output signal control section 111 controls the safety output to be ON when the determination result is the non-detection state. On the other hand, when the suppression state signal is set to "suppression," the safety output signal control section 112 controls the safety output to be OFF when the determination result of the second entry determination section 114 regarding the entry into the protection area A is the detection state, and the safety output signal control section 111 controls the safety output to be ON when the determination result is the non-detection state.

[0115] Fig. 24 and Fig. 25 show an example of operation regarding the conveyance of the workpiece W by the conveying device V of the Fig. 22, and Fig. 24(a) to 24(c) and Fig. 25(d) and Fig. 25(e) are time sequences. When the object N enters the protection area A of the photoelectric optical scanning switch 1 installed on the gate 100 at a time ( Fig. 24(a)) at which the workpiece W does not interfere with the first suppression sensor 101, an OFF signal (an operation-prohibiting signal) is output from the optical scanning photoelectric switch.

[0116] Fig. 24(b) shows a case where the front end of the workpiece W is located between the first suppression sensor 101 and the second suppression sensor 102, and the workpiece W interrupts the light emitted from the light projecting portion of the first suppression sensor 1. In this case, only the first suppression sensor 101 is in the detection state.

[0117] Fig. 24(c) shows a case where the leading end of the workpiece W interferes with the second suppression sensor 102, and the workpiece W interrupts the light emitted from the respective light projecting portions of both the first and second suppression sensors 101, 102. In this case, both the first and second suppression sensors 101, 102 are in the detection state, and by the first and second detection sensors 101, 102 entering the detection state in this order, the suppression function is performed in the suppression area 98 in the protection area A. Therefore, even if the workpiece W passes through the suppression area 98 in the protection area A of the optical scanning photoelectric switch 1 at the gate 100, no warning signal is output.

[0118] Fig. 25(d) shows a state where the rear end of the workpiece W interacts with the suppression region 98 of the optical scanning photoelectric switch 1, and the workpiece W also interacts with the third suppression sensor 103 on the downstream side of the gate 100. In this case, the suppression state is maintained.

[0119] Fig. 25(e) shows a state in which the rear end of the workpiece W interferes with the fourth suppression region 104 by the suppression sensor 103 entering the non-detection state, the suppression region 98 of the optical scanning photoelectric switch 1 is reset, and a warning signal is output immediately after the object M enters the protection region A of the optical scanning photoelectric switch 1.

[0120] Fig. 26 is a timing diagram of the Fig. 24 and Fig. 25. Each of the first to fourth suppression sensors 101 to 104 is at a low level (OFF state) in the non-detection state and outputs a high level signal (ON state) in the detection state.

[0121] It should be noted that in the time diagram of the Fig. 26 The word “YES” in the photoelectric optical scanning switch 1 means that an object M has entered the protection area A, and “NO” means that no object M has entered the protection area A.

[0122] As the workpiece W moves, the first to fourth suppression sensors 101 to 104 sequentially enter the detection state. When the time difference T1 between the first suppression sensor 101 entering the detection state and the second suppression sensor 102 entering the detection state is within a predetermined interval, a suppression signal is switched to a high level in synchronization with the rise of an output signal of the second suppression sensor 102, and suppression begins in the suppression region 98 of the optical scanning photoelectric switch 1. Therefore, during this suppression operation, the suppression region 98 in the protection region A of the optical scanning photoelectric switch 1 is practically an ineffective region.

[0123] When the elapsed time T2 from the start of the suppression state does not become less than the predetermined time Tc, and when the optical scanning photoelectric switch 1 senses the entry of the object (object M) into the protection area A without the suppression area, the suppression is forcibly ended. When setting the predetermined time Tc, the user can set an upper limit such as five minutes. Note that although the description has been given using photoelectric sensors as the first to fourth suppression sensors 101 to 104 as examples, a radio acoustic wave sensor, an ultrasonic sensor, or a touch sensor may be used as the suppression sensor.

[0124] Furthermore, when workpieces W having different heights are conveyed by the conveying device V according to a predetermined rule, the timing at which the workpiece W passes through the gate 100 may be detected by a sensor arranged on the upstream side of the gate 100, and based on a timing signal from this sensor, the suppression section 98 may be turned on in accordance with the height of the workpiece W.

[0125] Fig. 27 to 29 are views for explaining exemplary cases of setting a plurality of suppression areas 98 each corresponding to workpieces W having different heights and widths.

[0126] If a motor vehicle is taken as an example as the workpiece W, a first type of motor vehicle W has a relatively large height and a relatively small width. In contrast, a second type of motor vehicle W2 has a relatively small height and a relatively large width. With reference to Fig. 27 to 29, the left side of the two sides between which the gate 100 is located is the no-access area, the photoelectric optical scanning switch 1 is arranged at the central portion of the upper crossbar of the gate 100, and the scanning surface 39 of this photoelectric optical scanning switch 1 is set along a vertical surface surrounded by the gate 100, whereby a light curtain is formed by the photoelectric optical scanning switch 1 at the opening of the gate 100.

[0127] Each of the arrows emanating from the photoelectric optical scanning switch 1 shows an example of an optical axis of the photoelectric optical scanning switch 1. In Fig. 28, a first suppression area 98(1) in the shape of a relatively low trapezoid is set when the second type of vehicle W2 passes through the gate 100, and a second suppression area 98(2) in the shape of a relatively high trapezoid is set when the first type of vehicle W1 passes through the gate 100. If the passage order of the two types of vehicle W through the gate 100 has been previously set, the suppression area 98 is set according to the vehicle types in accordance with this order.

[0128] Fig. 30 to 32 show examples in which, in the case of conveying different types of workpieces W, a plurality of suppression areas 98 corresponding to the respective outer edges of the different types of workpieces W are set to thereby set the suppression area 98 corresponding to each workpiece W, the height of the workpiece W is defined by detecting it using the sensors 121 to 123, and the type of the workpiece W is defined based on this height.

[0129] With reference to Fig. 30 shows an example of control in which the photoelectric optical scanning switch 1 is arranged in a vertically downward direction on the gate 100, and a reflected light curtain is formed by the optical axes of this photoelectric optical scanning switch 1 at the opening of the gate 100. On its ascending column (pillar) 100a, a low-positioned sensor 121, a center-positioned sensor 122, and a high-positioned sensor 123 are arranged vertically spaced from each other at a low, middle, and high position. An example of control is that before the workpiece W enters the gate 100, that is,before the workpiece W passes through a light curtain formed by the optical axes of the photoelectric optical scanning switch 1, the height of the workpiece W is determined using a combination of the ON / OFF states of the low-positioned, the middle-positioned, and the high-positioned sensors 121 to 123, and the type of the workpiece W is determined based on this height to switch the suppression areas 98(1) to 98(4) corresponding to the respective outer edges of the workpieces W.

[0130] Fig. 31A shows a case where light enters all of the sensors 121 to 123 located at positions with different heights, namely the low, middle, and high positions. In this case, the workpiece W is considered to have a height such that it does not interfere with the low-positioned sensor 121, and therefore, a first suppression area 98 (low) that is relatively low or a first suppression area 98 (low) in which there is practically no suppression area is set.

[0131] Fig. 31B shows a case where, among the sensors 121 to 123 arranged at the positions with different heights, namely the low, middle, and high positions, the low-positioned sensor 121 interacts with the workpiece W and the light is interrupted. In this case, the workpiece W is considered to be higher than the design height of the low-positioned sensor 121 but lower than the design height of the centrally positioned sensor 122, and therefore, a second suppression area 98 (center) with a moderate height is set.

[0132] Fig. 32C shows a case where, among the sensors 121 to 123 arranged at positions with different heights, namely the low, middle, and high positions, the low-positioned sensor 121 and the centrally positioned sensor 122 interact with the workpiece W and the light is interrupted. In this case, the workpiece W is considered to be higher than the designated height of the centrally positioned sensor 122 but lower than the designated height of the high-positioned sensor 123, and therefore, a third suppression area 98 (high) is set, which is relatively high.

[0133] Fig. Figure 32(d) shows a case where light to all sensors 121 to 123 is interrupted at the low to high positions. In this case, the workpiece W is considered to be so high that it interferes with the high-positioned sensor 123, and therefore, a fourth suppression area 98 (ultra-high) with the largest height is set. This fourth suppression area 98 (ultra-high) may be the entire protection area A ("full suppression").

[0134] As just described, a plurality of arbitrary suppression areas 98 are set in the protection area A of the photoelectric optical scanning switch 1, an appropriate protection area 98 is set at the required time for a required period of time, and when another suppression area 98 is appropriate, the suppression area can be switched to this other suppression area 98.

[0135] It should be noted that once the output of the low-positioned, center-positioned, and high-positioned sensors 121 to 123 is in an ON state (the detection of the workpiece W = the light interruption state), the transition to the OFF state is not made immediately even if light is then incident, but the transition to the OFF state is made after light continues to be incident for a predetermined period of time. This predetermined period is set by the user so that the output of each of the low-positioned, center-positioned, and high-positioned sensors 121 to 123 is turned OFF after the workpiece W has completely passed through the light curtain formed by the optical axes of the photoelectric optical scanning switch 1.

[0136] In the case of Fig. 30 to 32, the suppression area 98 is provided in the protection area A, while a plurality of areas are set as the protection area 98 as the suppression area 98 to switch the suppression area 98 as needed. As a modified example of this, an area in which the protection area 98 (low) of the Fig. 31(a) has been removed, can be set as protection area A, and the suppression area 98 (low) can be added to this protection area A. Of course, an area where the suppression area 98 (central) of the Fig. 31(b) has been removed, can be set as protection area A, and the suppression area 98 (central) can be added to this protection area A. Similarly, in the case of the Fig. 32(c) an area where the suppression area 98 (high) of the Fig. 32(c) has been removed, can be defined as protection area A, and the suppression area 98 (high) can be added to this protection area A. Similarly, in the case of the Fig. 32(d) a range where the suppression range 98 (ultra-high) of the Fig. 32(d) may be designated as protection area A, and suppression area 98 (ultra-high) may be added to this protection area A.

[0137] Furthermore, when light is incident on each of the sensors 121 to 123 arranged at the positions having different heights, namely the low, middle and high positions, the protection area A (to which the first suppression area 98 (low) has been added) which is Fig. 31(a), and when the low-positioned sensor 121 interacts with the workpiece W and the light is interrupted, the protection area A can be switched to the protection area A (to which the second suppression area 98 (central) has been added) which is Fig. 31(b) and then set. Furthermore, when the low-positioned sensor 121 and the centrally positioned sensor 122 interact with the workpiece W and the light is interrupted, the protection area A may be switched to the protection area A (to which the third suppression area 98 (high) has been added) and then set, and when light is interrupted to all the sensors 121 to 123 at the low to high positions, the protection area A may be switched to the protection area A (to which the fourth suppression area 98 (ultra-high) has been added) and then set. Protection area switching control:

[0138] A plurality of protection areas A(1) to A(3) can be set in advance without a suppression area, and the protection area A can be switched in a predetermined order. Fig. 33 is an example for explaining an example to which such switching is applied. The photoelectric optical scanning switch 1 can be installed in advance both at the front end of a truck 133 that travels by itself along a specific travel route within a factory or the like, and the protection areas A(1) to A(3) are switched according to the state of the travel route 131. In this case, if it is assumed that three protection areas A(1) to A(3) are set, it may be allowed to set the order of switching these protection areas A(1) to A(3) in accordance with an input signal from the truck 130 (an operation of the truck 130) in advance. In the case of Fig. 33, the order of switching of the protection area A is set to “A(1)→A(2)→A(3)→A(1)”, and this switching of the protection area A can be set to be executed based on, for example, a signal from the truck 130 associated with the orientations of the tires of the truck 130.

[0139] Furthermore, if the stopping of the truck 130 is included when switching the protection area A, a function for temporarily shutting off the laser light emission can be considered, namely the light projection stop function. This function turns the safety output OFF, thus transmitting a prohibition signal to the truck 130. However, since the truck 130 has stopped before the laser light emission is stopped, it is not disadvantageous from a practical point of view, and during this time, it is possible to prevent unnecessary interaction of light with another photoelectric switch. A variety of output systems:

[0140] As described above, the optical scanning photoelectric switch is provided with the inhibit function as a safety device. While it has been proposed to provide the optical scanning photoelectric switch 1 with several more functions similar to the multi-optical axis photoelectric switch, and a new function may also be developed in the future, an inhibit function can be cited as an example. The inhibit function is a function that prevents the safety output of the optical scanning photoelectric switch 1 from automatically changing from the OFF state (prohibiting operation) to the ON state (permitting operation). This inhibit function is intended to prevent accidental activation or re-activation of a machine.

[0141] Furthermore, a start-lock function and a restart-lock function are implemented in the photoelectric optical scanning switch 1. The start-lock function is a function that, at the time of power on or power recovery after a power failure, keeps the safety output in the OFF state normally until the start-lock function is manually reset. The restart-lock function is a function that, at the time the photoelectric optical scanning switch 1 enters the OFF state during its operation, keeps the safety output in the OFF state until the restart-lock function is manually reset. Furthermore, whether these functions are enabled or disabled can be individually selected according to an operation mode. For example,In a manual start and manual restart mode, both locking functions are enabled; in a manual start and auto restart mode, the start locking function is enabled but the restart locking function is not enabled; and in an auto start, auto restart mode, both locking functions are not enabled.

[0142] It is preferable that the photoelectric optical scanning switch 1 has outputs of a plurality of systems, and the user is able to set a plurality of security functions such as the suppression function and the lock function, as well as an operation mode with respect to the output of each system. Fig. 34 shows an example of this. The work robot 2 is installed in a hazardous area surrounded by the safety fence 3, and this work robot 2 performs machining on the workpiece W on a workpiece support 140. This machining robot 2 has workpiece conveying tables 141a, 141b on its right and left sides, and each workpiece conveying table 141a (or 141b) is guided by a rail 142a (or 142b) to move backward and forward on its own. Each workpiece conveying table 141a (or 141b) can assume a first position near the machining robot 2 and a second position near an interface 143 that is remote from the machining robot 2 and has access to the outside. In this second position, the operator places a workpiece on the workpiece conveyor bench 141a (or 141b) and the workpiece conveyor table 141a (or 141b) moves to the first position when it has picked up the workpiece W.The machining robot 2 receives the workpiece from the workpiece conveying table 141a (or 141b) in the first position and machines the received workpiece W on the workpiece support 140.

[0143] Near the right and left interfaces 143a, 143b, protection areas A(a), A(b) are defined by the optical scanning photoelectric switch 1, respectively. Signals from the first and second suppression sensors 101a (or 101b), 102a, or 102b, which are located near each interface 143a or 143b, are input to this optical scanning photoelectric switch 1.

[0144] The photoelectric optical scanning switch 1 has first and second output systems 145, 146, wherein the first output system 145 is connected to a drive source of the workpiece conveyor table 141 and the second output system 146 is connected to a drive source of the machining robot 2. The second output system 146 of the photoelectric optical scanning switch 1 has the suppression function ( Fig. 35). The first output system 145 outputs an OFF signal to the workpiece conveyor table 141 as a safety output when the object M (e.g., the operator) enters the protection area A. The suppression function is set in the second output system 146, and while the suppression function is operating, even if, for example, the operator enters the protection area A, an ON signal (safety signal) is output to the machining robot 2 as a safety output regardless of the sensor detection of the entry.

[0145] The suppression function of the photoelectric optical scanning switch 1 is activated when the first and second suppression sensors 101a (or 101b), 102a (or 102b) sense the workpiece conveying table 141a (or 141b), and the operation of the suppression function is stopped when the first and second suppression sensors 101a (or 101b), 102a (or 102b) do not sense the workpiece conveying table 141a (or 141b).

[0146] Returning to Fig. 34 shows Fig. 34 shows a state in which the right workpiece conveying table 141a is positioned in the second position and the right interface 143a is closed by the right workpiece conveying table 141a. This right workpiece conveying table 141a places the first and second suppression sensors 101a, 102a in a light-interrupting state, and thereby the second output system 146 of the photoelectric switch for optical scanning 1 is in a suppression state. Therefore, even if an operator enters the right protection area A(a) and places the workpiece on the right workpiece conveying table 141a or receives the already machined workpiece W on the right workpiece conveying table 141a, the safety signal is output to the machining robot 2 because the second output system 146 is in the suppression state, and the machining robot 2 can perform machining.On the other hand, the first output system 145 generates a warning signal due to the operator's entry into the protective area A(a) and outputs the warning signal to the right workpiece conveyor table 141a, thereby bringing the right workpiece conveyor table 141a into a state where the operation is stopped. Even if the right workpiece conveyor table 141a receives the warning signal from the photoelectric optical scanning switch 1, it is reasonably not disadvantageous because the state of the right workpiece conveyor table 141a, which is in a stopped state near the right work interface 143a, remains unchanged, and meanwhile, it is possible to prevent abrupt operation of the right workpiece conveyor table 141a, thus preventing an entry path into the interior of the protective fence 3 from being created by opening the right interface 143a closed by the workpiece conveyor table 141a.

[0147] The left-side workpiece conveying table 141b is arranged in a position adjacent to the machining robot 2, and the left interface 143b is in an open state. Since an area near this left interface 143b has been designated as the protection area A(b) by the photoelectric optical scanning switch 1, warning signals are output to the left workpiece conveying table 141b and the machining robot 2 through the first and second output systems 145, 146 when the operator enters this left protection area A(b), and the left workpiece conveying table 141b and the machining robot 2 are stopped in an emergency.

[0148] Assuming that the optical scanning photoelectric switch 1 has only one output system, if this output is shared and the shared output of the optical scanning photoelectric switch 1 is connected to the workpiece conveying table 141 and the machining robot 2, the suppression function cannot be used to prevent abrupt operation of the workpiece conveying table 141a, and the machining robot 2 is stopped while the operator enters the protection area A and performs operations, even if the operation of the machining robot 2 does not pose a danger to the operator present in the protection area A, thereby reducing the work rate.For example, when the photoelectric optical scanning switch 1 has first and second output systems, even if the photoelectric optical scanning switch 1 is set to suppress, it is possible to make a setting such that the suppression function functions only in the second output system connected to the machining robot 2 and the suppression function does not function in the first output system 145 connected to the workpiece conveying table 141, so as to increase the work rate of the machining robot 2 while ensuring safety.

[0149] Furthermore, in addition to the foregoing example, for example, when the workpiece conveying tables 141a, 141b and the machining robot 2 are operated synchronously and an electric clamp (clamp), not shown, for holding the workpiece W is installed on each of the workpiece conveying tables 141a, 141b, the aforementioned first discharge system 145 is connected to a power source of the electric clamp and the aforementioned second discharge system 146 is connected to the machining robot 2 and the right workpiece conveying table 141a, which are operated synchronously, thereby allowing the operator to safely receive and transfer the workpiece W from the electric clamp, change the workpiece W, and remove the workpiece W from the electric clamp while the machining robot 2 is operating.It should be noted that, unlike the previous example, the right interface 143a, which is closed by the workpiece conveying table 141a, is opened due to the abrupt operation of the workpiece conveying table 141a, which may cause the generation of an entry path into the interior of the protective fence 3. However, in this case, the suppression state is reset because the suppression sensor 101 enters a non-detection state (light entry state). Therefore, at the time of suppression reset, the machining robot 2 and the workpiece conveying table 141a are stopped in an emergency manner, so that the safety of the operator can be ensured.

[0150] Here, emergency stop means the release of the restart prohibition function, and the restart prohibition function has been released on the second output system 146. In the previous two examples, when the second output system 146 enters the OFF state, the right interface 143a, which was closed by the workpiece conveying table 141a, is opened, which may cause the generation of an entry path into the interior of the safety fence 3. Therefore, after the second output system 146 enters the OFF state, since the operator has entered the protection area A, and even if the optical scanning photoelectric switch 1 considers that the operator has exited the protection area A, it cannot check whether the operator has exited the protection area 3 to the outside through the entry path or entered the interior of the safety fence 3, although it can determine that there is no object M in the protection area A.For this reason, a machine (danger source) connected to the second output system 146 is not automatically redesigned, and the photoelectric optical scanning switch 1 determines whether or not to put the second output system 146 into the ON state until a reset input manually after an artificial safety check is accepted.

[0151] On the other hand, since the first output system 141 is in the OFF state, even if the operator performs normal operation and the entry path is normally closed by the workpiece conveying table 141a, it can be assumed that the operator has exited the safety fence 3 to the outside if it can be verified by the photoelectric switch for optical sensing that there is no object M in the protection area A, it is preferable that the machine (danger source) connected to the first output system 145 be automatically restarted. This means that since the machine (danger source) has been stopped normally, it is preferable that the machine (danger source) be automatically restarted at the time the operator exits the protection area A, and thus work efficiency is also favorable.Accordingly, the first output system 145 may be set to a mode in which the restart prohibition function is not enabled, that is, the manual start and automatic restart mode or the automatic start and automatic restart mode. In contrast, the second output system 146 includes the emergency stop, and thus it is not desirable for the machine (hazard source) to be automatically restarted even if the operator leaves the protection area A. It is therefore preferable to operate the second output system 146 in the manual start and manual restart mode by enabling the restart prohibition function thereon. In addition, it may be configured so that when any one of a plurality of output systems on which the prohibition function has been enabled enters the OFF state, it is regarded as an emergency stop, and the other output systems are also brought into the OFF state.This can provide the advantage of automatic restart during normal operation and also brings all output systems to the OFF state at the time of emergency stop, and the state remains unchanged until the ON state, at least until a manually entered reset is performed, so that safety can be ensured.

[0152] As described above with respect to a plurality of functions and modes that can be set by the user in the photoelectric optical scanning switch 1, a single photoelectric optical scanning switch 1 is capable of dealing with various conditions in a rational manner because the photoelectric optical scanning switch 1 has a plurality of output systems and can be set with a function and a mode with respect to each of the output systems.

[0153] Furthermore, although the example in which a protection area A(1) is set was shown, this is not limiting, and protection areas can be assigned separately with respect to the first and second output systems 145, 146 through the user's setting. In the case of a configuration in which the protection areas are assigned separately, the configuration can be made such that a setting of one protection area can be reflected in a setting of the other protection area to thereby set the protection areas with identical shapes and positions, or the configuration can be made such that a setting mode for setting the protection areas with identical shapes and positions is provided. Furthermore, each of the first and second output systems 145, 146 is preferably configured with two outputs (OSSD1, OSSD2, OSSD3, OSSD4) having identical output states (ON state / OFF state).In the ON state, each output is superimposed with a self-diagnosis pulse, ie, an inspection signal with which the state changes from the ON state to the OFF state immediately (in such a time period that an external device connected to each output is prevented from detecting the change of the output to the OFF state), and the error measuring device 58 checks whether each output can be turned OFF at any time.

[0154] How to continue in Fig. As shown in Figure 36, the timing at which the self-diagnosis pulse is superimposed as an inspection signal is set differently for each output. That is, a configuration is preferably selected so that the superimposition at different times in time division allows the error measuring device 58 to verify that no output has been short-circuited. In other words, an error can be measured even if a short circuit occurs between the safety outputs.

[0155] When a safety signal indicating permission to operate is output based on an inspection signal superimposed on this safety signal, the safety detection device determines whether or not a safety signal indicating non-permission can be output in units of the output device (OSSD) using a self-diagnosis pulse. If it is determined that the signal cannot be output (output impossible), a safety signal indicating non-permission to operate is output instead of the safety signal indicating permission to operate, so that another output device (OSSD) in the same output system outputs the safety signal indicating non-permission to operate to the external machine (danger source), thereby allowing the external machine to recognize that safety has not been inspected.This can be due to the acceptance of a signal that does not permit operation or the inconsistency of the ON / OFF logic of the output devices (OSSD) in the identical output system. This ensures the safety of the photoelectric optical scanning switch 1. A variety of output systems and individual settings of capture capabilities:

[0156] If the photoelectric optical scanning switch 1 comprises a plurality of output systems, the detection capability, including a detection sensitivity, can also be made adjustable by the user with respect to each of the output systems. As also shown in Fig. 2, the setting of the sensing capability will be specifically described with respect to each output system. Assume that a first protection area A1 set with a normal capability as the sensing capability (normal capability) and a second protection area A2 set with a high capability while including the edge of the first protection area A1 are set by the user. In this case, such a setting can be made so that the drive source (motor) of the machine (robot) operates at a normal speed when a second safety output corresponding to the second protection area A2 is in the ON state, and the drive source (motor) of the machine (robot) operates at a low speed when the second safety output corresponding to the second protection area A2 is in the OFF state.Meanwhile, such a setting may be made that power is supplied to the drive source (motor) of the machine (robot) when a first safety output corresponding to the first protection area A1 is in the ON state, and no power is supplied to the drive source (motor) of the machine (robot) when the first safety output corresponding to the first protection area A1 is in the OFF state.Particularly in the case of a machine operating at high speed or a machine with high inertia force (high inertia), since the motor cannot be suddenly stopped even if the power supply to the motor is interrupted, the motor operation is switched to low-speed operation when the object (object M) is sensed in the second protection area A2, which extends further from the first protection area A1 with respect to the machine, thereby facilitating the sudden stop of the machine (motor) at the time of the sensory detection of the object (object M) in the first protection area A1. Accordingly, making the detection capability adjustable by the user's hand with respect to each of the two output systems can increase the speed at which the machine performs normal operation while ensuring safety.

[0157] In addition to detection sensitivity, examples of adjustable detection capability include response time, minimum detected object, and light receiving sensitivity. The response time is a setting condition corresponding to the predetermined time or the time taken for a predetermined number of consecutive measurements of the object M in the protection area A when the optical scanning photoelectric switch 1 detects the presence of the object M within the protection area A only after the predetermined time has elapsed or after the predetermined number of consecutive measurements have elapsed. Therefore, the detection capability becomes high when the response time is short, and the detection capability becomes low when the response time is long.The smallest detectable object is an object with the minimum size among the objects whose sizes can be reliably detected by the photoelectric optical scanning switch 1, and depends on the optical axis density of the photoelectric optical scanning switch 1. The detection capability becomes high when the set smallest detectable object is small (the optical axis density is high), and the detection capability becomes low when the set smallest detectable object is large (the optical axis density is low). For example,The configuration is such that the number of optical axes for detecting an object is fixed at each scanning, and the optical scanning photoelectric switch 1 determines the presence of the object M in the protection area A only after the object M is detected, with the number of optical axes not less than the fixed number, thereby making it possible to practically change the optical axis density to change the detection performance. Light reception sensitivity means the gain of a light reception signal or a threshold value with respect to the light reception signal. The detection performance increases by increasing the gain or decreasing the threshold value, and the detection performance increases by decreasing the gain or increasing the threshold value.

[0158] Although the respective relationships of detection capability and safety function (suppression function, etc.) with the plurality of output systems have been described separately, it goes without saying that the detection capability and safety function can be combined and then set with respect to each output system. Regarding the individual setting of the detection capability with respect to each of the plurality of output systems, the setting is of course effective not only in the optical scanning photoelectric switch 1, but also in the safety devices such as the multi-optical-axis photoelectric switch and the single-optical-axis photoelectric switch.If the multi-optical-axis photoelectric switch is installed horizontally on the floor, one or a plurality of optical axes on the side closer to the machine (danger source) are assigned to the first safety output, and one or a plurality of optical axes on the side farther from the machine (danger source) are assigned to the second safety output. As in the above example, the first safety output can be set to have a normal detection capability, and the second safety output can be set to have a relatively high detection capability. Here, as described above, the detection capability means the response time, the smallest detectable object, the light receiving sensitivity, or the like.

[0159] On the other hand, regarding the individual setting of the safety function with respect to each of a plurality of output systems, the setting is effective in a safety device such as the photoelectric optical scanning switch capable of detecting the position of the object M. Apart from the photoelectric optical scanning switch, a safety image switch can be used. In the case of a safety image switch with an image element built therein, the protection areas with respect to the first and second safety outputs can be set on a captured two-dimensional image, or a protection space can be set with respect to a three-dimensional maximum protection space detected from the two-dimensional images captured with one or a plurality of safety image switches, thereby individually setting the safety function with respect to each of the first and second output systems.

[0160] Furthermore, although the optical scanning photoelectric switch 1 in the above examples is configured to set the safety function such as the suppression function or the lock function, or to set the detection performance such as the response time, the smallest detectable object, or the light receiving sensitivity with respect to each of the plurality of output systems, it may be configured to select a state of unchanged reproduction of an output state of another output system and to independently set only a superimposed self-diagnosis pulse with respect to each output, or to set a state of fixing the output system to the OFF state by the user. The same applies to the safety image switch. Countermeasure against interference between photoelectric switches:

[0161] As above with regard to Fig. 33, for example, in the case where the optical scanning photoelectric switch 1 is mounted on the traveling truck 130, and another scanning photoelectric switch 1 is installed near the traveling path 131, there is a possibility that, during the moving operation of the traveling truck 130, interference may occur between the optical scanning photoelectric switch 1 mounted on the truck 130 and another optical scanning photoelectric switch 1 mounted near the traveling path 131. Of course, this is a mere example, and there is also a possibility that interference problems may occur between optical scanning photoelectric switches 1 mounted on a plurality of traveling trucks 130 when these trucks 130 approach each other.As another example, a case where the interaction problem occurs between a plurality of fixed photoelectric optical scanning switches 1 can also be cited. This problem is not limited to that between photoelectric optical scanning switches 1, but the interaction problem may even occur between a photoelectric optical scanning switch 1 and another type of photoelectric switch (synonym for a photoelectric sensor).

[0162] Fig. 37 shows a case where light projected from both of the adjacent photoelectric optical scanning switches 1A, 1B enters each other to cause interference (interference, interaction), and an example where laser light reflected from a surrounding structure enters each switch and causes interference, and Fig. Figure 38 is a timing chart for the projection of light pulses when the adjacent optical scanning photoelectric switches 1A, 1B interact with each other. When the interaction problem occurs between adjacent optical scanning photoelectric switches 1, 1B, it becomes a cause of the problem that prevents accurate calculation of the distance to the object (object M).

[0163] The photoelectric optical scanning switch 1 is set to operate with the following parameters: (1) As described above, the optical scanning photoelectric switch 1 is provided with a photoelectric rotary encoder 25 that operates using the theory of light passing through a plurality of slits equally spaced in a circumferential direction, and the light projection timing of the light projection element LD is defined using an output of the rotary encoder 25. Therefore, an angular resolution is 0.36 degrees as described above; (2) a rotation period (scanning period) is 30 ms; and (3) a light projection period is 30 µs. That is, if light is projected every 0.36 degrees in a 360-degree rotation, a total of 1,000 light projection operations are performed in the 360-degree rotation. If 30 ms is set as the rotation period (scanning period) in one rotation, the light projection period is {300 ms / 1,000}, that is, 30 µs. The sampling time, iethe duration of one revolution of the scanning mirror 14 is determined by a rotational speed of the motor 24.

[0164] A technique for avoiding interference between the photoelectric optical scanning switch 1 and an adjacent photoelectric switch (synonym with a photoelectric sensor) is described in Fig. 42 shown. Fig. 42 shown. Fig. Fig. 42 shows a timing chart for light projection pulses of a first and second photoelectric optical scanning switch 1A, 1B. As can be seen from this Fig. As can be seen from Fig. 42, for the light projection pulse durations of the first and second optical scanning photoelectric switches 1A, 1B, the duration in the first optical scanning photoelectric switch 1A is set to 30 ms, while the duration in the second optical scanning photoelectric switch 1B is set to 33 µs. The pulse widths of the light projection pulses of these switches are the same, and making the pulse widths equal can suppress interference in detection sensitivity. By setting the light projection durations differently between the first and second optical scanning photoelectric switches 1A, 1B in this way, even if mutual interference occurs between any optical axes, a phase difference of 36 degrees in the rotation period is generated in the next scanning, and thus no interference occurs subsequently in a plurality of scanning operations.In this context, generally, in a photoelectric switch, an output is changed only after a plurality of sensory measurements are performed in order to avoid erroneous operation due to noise or suspended particles, and therefore, setting different light projection times between a plurality of photoelectric switches can practically avoid erroneous detection due to interference between adjacent photoelectric switches.It should be noted that in the optical scanning photoelectric switch 1, generally, reflected light is received on the scanning mirror 14 and the light is then collected on the light receiving lens 20 to acquire a light receiving signal, and therefore, generally speaking, the problem of interaction will not occur as long as there is a shift in orientation between the optical scanning photoelectric switches 1 even if light is received simultaneously.

[0165] Fig. Fig. 43 is a diagram showing in block form a basic configuration of the photoelectric optical scanning switch 1, and the photoelectric optical scanning switch 1 of this Fig. 43 is compatible with the previous two output systems ( Fig. 35). A rotational speed of the motor 24 can be set as the light projection pulse duration, and for this, light projection / reception timings of the control device 30 can be set, typically using an external PC. Of course, the light projection / reception timings can also be made adjustable by displaying the set points on the liquid crystal display section 34 of the photoelectric optical scanning switch 1 and the user operating the operation buttons 36. The set light projection / reception times, i.e., the light projection / reception durations, are stored in an internal memory 147 together with the set protection area A and the like.

[0166] Fig. Fig. 44 is a diagram for explaining a second technique for preventing mutual interference of a plurality of photoelectric switches. This example of Fig. Figure 44 is made assuming that the first to fourth optical scanning photoelectric switches 1A to 1D are mutually connected by a synchronous line. In other words, the timings of each of the first to fourth optical scanning photoelectric switches 1A to 1D are defined by signals from the synchronous line, and setting a phase difference between the light projection pulses can prevent mutual interference of the first to fourth optical scanning photoelectric switches 1A to 1D. When the timing for detecting a light reception signal after light projection by the optical scanning photoelectric switch 1 is generally 2 μs, setting 3 μs as the phase difference can solve the interference problem.

[0167] Fig. Figure 45 is a diagram for explaining a third technique for preventing mutual interference of a plurality of photoelectric switches. This example of Fig. 45 suggests that when interference occurs between two adjacent photoelectric switches 1, 1 and this is then sensed, a phase difference is detected by changing the light projection times of a next optical axis or thereafter of one or both photoelectric switches for optical scanning. As a technique for sensing the interference, for example, when light reception is detected discontinuously on a specific optical axis, but not a plurality of consecutive events and a frequency of such non-detection is not less than a predetermined frequency, this can be regarded as interference between the photoelectric switches. Of course, in a modified example, such a control could be added that the light projection pulse duration or light projection duration (rotational speed of the motor 24) described in Fig. 42, is changed as soon as the interference is detected by sensors. With regard to the detection of the interference, building on the previous examples, a control could be added such that the light projection pulse duration or the light projection duration (rotational speed of the motor 24) is changed as soon as the possibility of interference is determined, which is based on a time difference t between light projection and light projection, as will be explained later with reference to the flow chart of the Fig. 51 is described.

[0168] The above three techniques are techniques for making the rotation speed of the motor 24 different between adjacent photoelectric optical scanning switches 1, 1, thus making the scanning period between them different to avoid mutual interference. As a modified example, in which the light projection timing of the photoelectric optical scanning switch 1 is controlled by a clock, the light projection period can be made different between adjacent photoelectric optical scanning switches 1, 1. That is, a configuration is used in which the light projection pulse duration is made different between adjacent photoelectric optical scanning switches 1, 1.

[0169] Furthermore, regarding the change in the setting of the rotational speed of the motor 24 or the light projection pulse width of the photoelectric optical scanning switch 1, such a change cannot be made using the external personal computer PC, but it may be allowed to be made using the liquid crystal display section 34 and the operation keys 36 of the photoelectric optical scanning switch 1 without the external personal computer PC, as described above. While this photoelectric switch 1, as will be described later with reference to Fig. 48, is capable of setting multiple parameters using the liquid crystal display section 34 and the operation buttons 36, adding the rotational speed of the motor 24 or the light projection pulse duration as one of the set parameters can prevent interference among adjacent photoelectric optical scanning switches 1, 1 by the user without using the external personal computer PC. Furthermore, a configuration may be selected such that a plurality of the light projection pulse durations or a plurality of the light projection durations (rotational speed of the motor 24) are stored in advance in the internal memory 147 ( Fig. 43) of the photoelectric optical scanning switch 1, and a desired light projection pulse duration or a desired light projection duration (rotational speed of the motor 24) can be arbitrarily selected and then adjusted by the user via the stored durations. If, based on the aforementioned time difference t from light projection to light reception ( Fig. 51) that interference may have occurred, control may of course be performed to change the light projection pulse duration or the light projection duration (rotational speed of the motor 24) to another light projection pulse duration or light projection duration (rotational speed of the motor 24) stored in the internal memory 174.

[0170] Although the technique for solving the problem of interference with another photoelectric switch (photoelectric switch) with reference to Fig. 37 to 45, there is another problem besides this, namely, a problem due to noise. When noise is superimposed on the reflected light of the optical scanning photoelectric switch 1, this tends to lead to a problem of mismeasurement of position information. To address this problem, the optical scanning photoelectric switch 1 firstly employs the light-transmitting cover 62 having the function of an optical filter and secondly employs the filter circuit to remove a signal having a frequency component different from the reflected light from the object (object M), however, the problem has not been completely solved.

[0171] If interference might be caused by stray light, the user adjusts an angle or height at which the photoelectric optical scanning switch 1 is installed, and at the time of this adjustment, it is advantageous to check from which direction the stray light is incident. If it is further checked whether the interference caused by the stray light disappears after adjustment, it is unnecessary to repeat the adjustment of an installation position of the photoelectric optical scanning switch 1 every time a malfunction of the photoelectric optical scanning switch 1 occurs. Since, as described above, the photoelectric switch is generally adjusted to change its output after sensing that the measured values ​​taken several times, iethe measured distance values ​​are successively within the protection area A, although the stray light does not directly induce a malfunction, the photoelectric optical scanning switch 1 can also be operated when its detection capability is in a deteriorated state (with a prolonged response time), which is not desirable for the photoelectric optical scanning switch 1 in terms of a safety device.

[0172] The photoelectric optical scanning switch 1 has three functional modes: (1) an "operation mode"; (2) an "observation mode"; and (3) a "setting mode". When the functional mode is switched, the display on the liquid crystal display section 34 of the photoelectric optical scanning switch 1 becomes a display of the Fig. 46 switched. Fig. 46 is a transition diagram for the display of the liquid crystal display section 34, wherein reference symbol 34(a) denotes the display during operation in the operation mode, reference symbol 34(b) denotes a menu screen of the observation mode, and reference symbol 34(c) denotes a menu screen of the setting mode.

[0173] With reference to the previous Fig. 6B, in the user interface section 32, the operation buttons 36a to 36e are arranged adjacent to the liquid crystal display section 34. The upper and lower buttons 36a, 36b are buttons for entering a numeric value and switching a display screen. For example, the upper button 36a can be used as an up arrow button for incrementation. Furthermore, the lower button 36b can be used as a down arrow button for decrementation. Three operation buttons 36c to 36e are arranged adjacent to each other below the liquid crystal display section 34, and these operation buttons 36c to 36e are used as buttons for switching function modes and specifying a setting value. For example, the central operation button 36c can be used for switching modes, the right operation button 36e is an Enter key, and the left operation button 36d is an Escape key (Esc key).

[0174] When the "operation mode" is selected, the photoelectric optical scanning switch 1 performs sensor detection of the entry of the object M. Switching from the "operation mode" to the "observation mode" can be performed by pressing the center operation button 36c. Furthermore, during operation in the "observation mode," the mode can be returned to the "operation mode" by pressing the left operation button 36d (Esc key).

[0175] With reference to Fig. 47, the "observation mode" is the functional mode for displaying an input / output state, an area observation status, measurement histories, and the like. As the input / output state, a safety output state of the photoelectric optical scanning switch 1, an input state from an external trigger circuit, and the like can be displayed on the liquid crystal display section 34 for observation. As the area observation status, the shape or size of a specified observation area, a distance to a sensor-detected entered object, and the like can be observed. As measurement histories, the position of the object entry, which trigger was used to output an operation-prohibiting signal, the time of sensor detection of the object, error information, and the like are recorded as measurement histories when the safety output is OFF.In the fault information histories, the time of switching the safety output and a turn-off factor (a cause for turning off the safety output) are included, and when the safety output is turned OFF due to stray light, an optical axis number defining a direction of the stray light is included in the fault information histories.

[0176] The measurement histories can be displayed sequentially from the most recent. A maximum of 20 measurement histories are recorded for such measurement histories, and the oldest measurement histories are deleted sequentially each time a new one is received. As position information of the incoming object, for example, a numerical value indicating the position of the incoming object is displayed using an orthogonal coordinate with the photoelectric optical scanning switch 1 as the center. Alternatively, a numerical value indicating the distance D from the safety sensor 1 to the incoming object is displayed. Furthermore, as error information, information indicating the occurrence of a defect due to contamination of the translucent cover 62, a short circuit at the output, or the like is displayed.In addition to the position information and error information, there is also information available as historical information indicating a test input from external devices. This test input is an external input for verifying whether the safety output is properly disabled or not.

[0177] The "Setting Mode" is the functional mode for setting parameters, defining the protection zone A, and setting external inputs. Transition from the "Operation Mode" to the "Setting Mode" can be performed by pressing the middle operation button 36c. Furthermore, while operating in the "Setting Mode," the mode can be returned to the "Operation Mode" by pressing the left operation button 36d (Esc key). When setting a home screen, selectable menu items are arranged, and a desired menu item can be selected by pressing the upper and lower operation buttons 36a, 36b.

[0178] Fig. Figure 48 shows an example of a screen display related to parameter settings in the setting mode. Parameters whose settings can be changed include the restart setting, an EDM, a measurement resolution, a response time, and the like. Regarding the restart, it is possible to select whether the photoelectric optical scanning switch 1 is restarted manually or automatically. Regarding the EDM, it is possible to select whether an external trigger observation function is turned ON or OFF. The measurement resolution of the entering object (object M) can be arbitrarily specified within a predetermined range.

[0179] The error information can be monitored by the external personal computer PC ( Fig. 13) connected to the photoelectric optical scanning switch 1. An application for displaying the error information histories is installed in the external personal computer PC, and using this program, the error information histories can be displayed on the display 81 of the personal computer PC.

[0180] Fig. 49 shows a screen display of stray light included in a display of fault information using the personal computer PC. On the display 81 of the personal computer, on one side thereof, the histories of the fault information are displayed in a time sequence. The list display includes, with respect to each piece of fault information: (1) a fault cause; (2) a time of fault occurrence; and (3) preferably the number of an optical axis in which the fault occurred. When the user selects an arbitrary fault history, the direction of the stray light is displayed in a highlighted color along with a symbol S for the photoelectric optical scanning switch 1. Whether this stray light display is continuously displayed or not continuously displayed but displayed at the user's request can be selectively set. Fig. Fig. 49 illustrates an exemplary display of the screen 81 of the personal computer PC when the photoelectric switch for optical scanning 1 connected to the personal computer PC is in an operating state, which is a state in which the operation of the photoelectric switch for optical scanning 1 is continuously observed by means of the personal computer PC. In this Fig. 49, black circles visible around the symbol S of the photoelectric optical scanning switch 1 indicate the trajectories of the position of the cause at the time when the safety output enters the OFF state, e.g., the trajectories of a position where the object M was detected in the protection area A. In Fig. 49, stray light is visible in large numbers in the dashed area extending upwards in the form of a sector from the symbol S. This stray light is indicated by a straight line emanating from the symbol S. Therefore, the user can see the direction of the stray light by looking at the straight line emanating from the symbol S.

[0181] Furthermore, when interference light is detected as described below, it is preferable to display it with letters on the liquid crystal display section 34 of the photoelectric optical scanning switch 1, namely as “Warning, Light Interference”, as shown in Fig. 50 is shown.

[0182] A method for sensing noise is presented. When the projected light hits and is reflected from the object (object M), the optical scanning photoelectric switch 1 measures a distance based on a time difference t between the time of light projection and the time of light reception, and measures a direction using the optical axis number of the received light. Furthermore, the optical scanning photoelectric switch 1 is generally designed to correct the measured distance using the light reception intensity to thereby increase the accuracy of distance measurement. Therefore, when the time difference t between the time of light projection and the time of light reception is within a predetermined range, the light can be regarded as light reflected from the object (object M) and as regular light.In other words, if the time difference t between the time of light projection and light reception is very small, the light can be regarded as noise light. Furthermore, if the time difference t between the time of light projection and the time of light reception is very large, the light can also be regarded as noise light. Therefore, if the time difference t between the time of light projection and the time of light reception is outside the predetermined range, namely, if the time difference t is smaller than the predetermined range or the time difference t is larger than the predetermined range, it is stored in the error history, and an error display is made on the liquid crystal display section 34 of the photoelectric optical scanning switch 1.Furthermore, if the photoelectric optical scanning switch 1 is provided with an indicator indicating a direction, the direction of the stray light is preferably indicated with this indicator.

[0183] What is problematic in ensuring safety is the case where the time difference t between the timing of light projection and the timing of light reception is smaller than the predetermined range, and in this case, in the photoelectric optical scanning switch 1, it is preferable to perform the adjustment of the output state of the photoelectric optical scanning switch 1 to the OFF state.

[0184] Fig. 51 is a flowchart showing an example of a specific technique for sensory detection of a disturbance. As described above, light projection is performed in a predetermined period of time (step S10), and it is determined whether or not light is received with respect to each optical axis number (step S11). If light is received, a time difference t from the light projection to the light reception of a corresponding optical axis number is calculated (step S12), and it is determined whether this time difference t is within a range between a previously set minimum time difference Tmin and a maximum time difference Tmax (step S13). If the result of the determination is "YES", that is,If the actual time difference t is within the predetermined range, the process proceeds to step S14, and in the same manner as conventionally done, a position of the (distance to) the object (object M) is measured. Note that the direction of the object (object M) can be defined by the number of the optical axis, that is, by the light projection time. If the object (object M) is within the protection area, the process proceeds from step S15 to step S16, where the output of the photoelectric optical scanning switch 1 is switched to the OFF state, and in step S17, an OFF trace is generated and then stored in the memory 147 (. Fig. 43). If the object (object M) is located in the warning area, the process proceeds from step S18 to step S19, where an operator who has entered the warning area is warned, for example, by a red lamp illuminating or an alarm sounding.

[0185] If it is determined in step S13 that the time difference t from light projection to light reception is outside the range between the minimum time difference Tmin and the maximum time difference Tmax, an abnormality is determined. That is, step S13 represents a device for determining an abnormal condition, and if the abnormal condition is determined, the process proceeds to step S20, where an error history is generated and then stored in the memory 147 ( Fig. 43). If the time difference t from the light projection to the light reception is smaller than the minimum time difference Tmin, in step S21, this can be further regarded as a phenomenon in an area near the photoelectric optical scanning switch 1 and is thus considered as something that could potentially compromise safety, whereby the process proceeds to step S22, where the output of the photoelectric optical scanning switch 1 is switched to the OFF state, and in step S23, an OFF trace is generated and then stored in the memory 147 ( Fig. 43). It should be noted that when the abnormal condition is determined in step S13, a display is made on the liquid crystal display section 34 indicating the abnormal condition ( Fig. 50).

[0186] By referring to the fault history and the OFF-state history, the user can clearly determine whether the cause of the problem is a temporary factor (e.g., dust) or a permanent factor (noise). If the cause is considered to be noise, the direction can be specified by displaying the OFF-state history and the fault history as detailed information about the disturbance using the external personal computer (PC), and thus the angle or height at which the photoelectric optical scanning switch 1 is installed can be changed to cope with the problem.

[0187] As with reference to Fig. 50, an error display can be performed using the liquid crystal display section 34 provided on the photoelectric optical scanning switch 1, and when viewing the display and finding it necessary, the user can perform an analysis of the disturbance light using the external personal computer PC. However, as shown in Fig. 52, a direction indicator 160 capable of indicating a direction is provided on the photoelectric optical scanning switch 1, and the direction of the cause of the problem can be indicated using this direction indicator 160. In this regard, on the top side of the Fig. 52, a plurality of LEDs 160a are evenly spaced in the shape of an arc, which are capable of indicating the direction of the cause of the problem by lighting the LED indicator 160 which corresponds to the direction. Specific adjustment procedure of the detection sensitivity holding / adjusting mechanism of the photoelectric optical scanning switch 1:

[0188] With reference to Fig. 9 to 12, the aforementioned detection sensitivity holding / adjusting mechanism will be described in detail. This detection sensitivity holding / adjusting mechanism includes, as reference objects, two first and second reflection surfaces 73, 74 having different reflection factors within the optical scanning photoelectric switch 1. The optical scanning photoelectric switch 1 has been provided with such a configuration that the first and second reflection surfaces 73, 74 serve as reference objects within a valid range of rotation of the scanning mirror 14, that is, a range different from the measurement range, and thereby a light projection path, a light reception path, a laser light source LD, and a light reception element (photoelectric conversion element) 22 used for scanning in the measurement range are shared.It is therefore possible to check the decrease in the detection sensitivity of the photoelectric optical scanning switch 1 by projecting light onto the reference objects (first and second reflection surfaces 73, 74) in the invalid rotation range of the scanning mirror 14 outside the measurement range and observing the light reception signal information obtained thereby.

[0189] At the time of delivery of the photoelectric optical scanning switch 1 from the factory, a light projection intensity and / or a light reception gain are adjusted so that an optimal detection sensitivity satisfactory in the application of the product is obtained when a scanning area in which the light-transmitting cover 62 is not sensed, that is, the first and second reflection surfaces 73, 74, is scanned with pulsed laser light. When this adjustment has been completed, for example, when a light reception intensity at the time of light projection on the optical axis number "60" is "600" (this optical axis number "60" corresponds to an optical axis number at the time of light projection to the second reflection surface (white) 74), the light reception intensity "600" of the optical axis number 60 is stored in the memory 174 ( Fig. 43). Furthermore, for example, if the light receiving intensity at the time of light projection onto an optical axis number "10" is "100" (this optical axis number "10" corresponds to an optical axis number at the time of light projection onto the first reflection surface (black) 73), the light receiving intensity "100" of the optical axis number 10 is stored in the memory 174 ( Fig. 43) are stored.

[0190] The above process at the time of delivery from the factory is based on Fig. 53. First, in step S100, the light reception signal information obtained when pulsed laser light is projected onto an object through the light-transmitting cover 62 is recorded, and the distance to the object is measured. Then, in step S101, it is determined whether or not the object can be sensed. If the result of the determination is "NO," the process proceeds to step S102, where the light projection drive section 150 ( Fig. 43) is controlled to increase the light projection intensity and / or an increase in the voltage of the power supply circuit 152 ( Fig. 43) to increase the light reception gain of the light reception element 22, and the process proceeds again to step S100, where the distance to the object is measured based on the light projection intensity and / or the light reception gain after adjustment. If it is determined in step S101 that the object has been sensed, the process proceeds to step S103, where the light reception signal information obtained when the pulsed laser light was projected onto the object through the light-transmitting cover 62 is recorded, and the distance to the object is measured.

[0191] In the next step S104, it is determined whether the light-transmitting cover 62 has been sensed or not, and if the result of the determination in step S104 is “YES”, the light projection driving section 150 ( Fig. 43) so that the light projection intensity is reduced and / or the voltage of the power supply circuit 152 ( Fig. 43) is reduced to thereby reduce the light reception gain of the light reception element 22, and then the process proceeds to step S103, where the distance to the object is measured based on the light projection intensity and / or the light reception gain after adjustment. If the sensory detection of the light-transmitting cover 62 is not detected in step S104, it is assumed that the light projection intensity and the light reception gain could be adjusted to optimal values, and the process proceeds to step S106, where a light reception intensity at the time of light projection to the white second reflection surface 74 (referred to as "reference light reception intensity RE (white)") is stored in the memory 174 ( Fig. 43). Furthermore, in the next step S107, a light reception intensity at the time of light projection to the black first reflection surface 73 is stored as another reference object (referred to as “reference light reception intensity RE (black)”) in the memory 174 ( Fig. 43) is stored.

[0192] The procedure before factory delivery was described above. The following is based on Fig. 54, a method is described for automatically adjusting a detection sensitivity for the photoelectric optical scanning switch 1. First, in step S200, a light receiving intensity at the time of light projection onto the optical axis number 50 (the white second reflection surface 74 ( Fig. 12)). This light reception intensity can be converted by an A / D converter 154 ( Fig. 43) representing a light receiving section. This recorded light receiving intensity is referred to as the "actual light receiving intensity (white)". The "reference light receiving intensity RE (white)" is then retrieved from the storage section 174 (step S201), and in the next step S202, it is determined whether the "actual light receiving intensity (white)" is smaller than the "reference receiving intensity RE (white)". If the result in step S202 is "YES", it is assumed that the actual light receiving intensity (white) has decreased, and the process proceeds to step S203, where the light projection drive section 150 ( Fig. 43) is controlled so that the light projection intensity is increased and / or the voltage of the power supply circuit 152 ( Fig. 43) is increased to thereby increase the light receiving gain of the light receiving element 22. In the next step S204, it is determined whether the "actual light receiving intensity (white)" is greater than the "reference light receiving intensity RE (white)" or not. If the result is "YES", it is assumed that the "actual light receiving intensity (white)" has become brighter, and the process proceeds to step S205, in which the light projection drive section 150 ( Fig. 43) is controlled so that the light projection intensity is reduced and / or the voltage of the power supply circuit 152 ( Fig. 43) is reduced so as to reduce the light receiving gain of the light receiving element 22.

[0193] The following is based on Fig. 55, a method for the photoelectric optical scanning switch 1 in which an error is automatically detected is described. First, in step S300, a light receiving intensity at the time of light projection on the optical axis number 10 (the black first reflection surface 73 ( Fig. 12)). This light reception intensity can be converted by the A / D converter 154 ( Fig.43), which constitutes the light receiving section. This recorded light receiving intensity is referred to as the "actual light receiving intensity (black)." The "reference light receiving intensity RE (black)" is then retrieved from the storage section 147 (step S301), and in the next step S302, it is determined whether the "actual light receiving intensity (black)" is less than the "reference reception intensity RE (black) - allowable value." If the result in step S302 is "YES," it is assumed that the "actual light receiving intensity (black)" has decreased extremely, and the process proceeds to step S303, where it is determined that the optical scanning photoelectric switch 1 is out of order and is thus switched to a safety state. Typical processing for this safety state is the processing for turning OFF the output of the optical scanning photoelectric switch 1.

[0194] Furthermore, when the "actual light reception intensity (black)" is also greater than the "reference light reception intensity RE (black) + allowable value", the processing proceeds from step S204 to step S303, where it is determined that the photoelectric optical scanning switch 1 is out of order and is thus switched to the safety state.

Claims

[1] A photoelectric switch which projects and receives light to detect the presence of an object in a predetermined two-dimensional or three-dimensional protection area by means of the light from the object within the protection area, and which is provided with a safety function which can be set by a user, the photoelectric switch comprising: a controller configured to determine an ON or OFF state as a first safety signal signifying an operation permit / non-permission for an external device based on the presence of the object within a first protection area of ​​the protection area and a first setting of the safety function, and to determine an ON or OFF state as a second safety signal signifying an operation permit / non-permission for an external device based on the presence of the object within a second protection area of ​​the protection area and a second setting of the safety function, wherein the safety function is related to a suppression function or a blocking function; and a plurality of output systems with a first output system associated with the first safety signal and with a second output system associated with the second safety signal, wherein the first setting of the security function and the second setting of the security function are individually user-adjustable with respect to each of the plurality of output systems. [2] A photoelectric switch according to claim 1, wherein an inspection signal is superimposed on each output of the plurality of output systems at different timings in time division. [3] The photoelectric switch according to claim 1, wherein a detection capability of the photoelectric switch is user-adjustable, and the detection capability is user-adjustable with respect to each of the plurality of output systems. [4] A photoelectric switch according to any one of claims 1 to 3, wherein the safety function is a lock function which prevents the safety output of the photoelectric switch from changing from an OFF state to an ON state. [5] The photoelectric switch according to any one of claims 1 to 4, wherein the photoelectric switch is a multi-optical axis photoelectric switch or an optical scanning photoelectric switch. [6] The photoelectric switch according to claim 5, wherein the safety function is a suppression function which temporarily disables the optical axes of all or part of the optical axes of the multi-optical axis photoelectric switch or the optical scanning type photoelectric switch. [7] A photoelectric switch according to claim 6, wherein the setting or non-setting of a security signal indicating non-permission with respect to each of the plurality of output systems is user-adjustable. [8] A photoelectric switch according to any one of claims 5 to 7, wherein an inspection signal is superimposed on each output of the plurality of output systems at different times in time division, and the setting of reflecting an output state of one output system as it is in an output state of the other output system is user-selectable. [9] A photoelectric switch that projects and receives light to detect the presence of an object in a predetermined two-dimensional or three-dimensional protection area using the light from the object within the protection area, and wherein the detection capability of the photoelectric switch is adjustable by a user, the photoelectric switch comprising: a controller configured to determine an ON or OFF state as a first safety signal indicating permission / non-permission for an external system to operate based on the presence of the object within a first protection area of ​​the protection area and a first setting of the detection capability, and to determine an ON or OFF state as a second safety signal indicating permission / non-permission for an external system to operate based on the presence of the object within a second protection area of ​​the protection area and a second setting of the detection capability, wherein the detection capability is related to a detection sensitivity, a response time, a smallest detected object, and a light reception sensitivity, and a plurality of output systems with a first output system associated with the first safety signal and with a second output system associated with the second safety signal, wherein the first detection capability setting and the second detection capability setting are individually user-adjustable with respect to each of the plurality of output systems. [10] A photoelectric switch according to claim 9, wherein inspection signals are superimposed on the respective outputs of the plurality of output systems at different times in time division. [11] A photoelectric switch according to claim 9, wherein the user-adjustable detection capability is a response time necessary to determine the presence of the object after sensing the object. [12] A photoelectric switch according to claim 9, wherein the user-adjustable detection capability is the size of a smallest detected object, which indicates a minimum size among the sizes of the objects detectable and detectable by the photoelectric switch. [13] A photoelectric switch according to claim 9, wherein the user-adjustable detection capability is the light receiving sensitivity of the photoelectric switch. [14] A safety control method using a photoelectric switch, comprising: Providing the photoelectric switch according to claim 1, which is a photoelectric optical scanning switch, wherein the first protection area set next to a danger source and the second protection area set at the edge of the first protection area are settable by the user as protection areas of the photoelectric optical scanning switch; Outputting a safety signal relating to the first protection area by means of the first output system and a safety signal relating to the second protection area by means of the second output system from among the outputs of a plurality of systems of the photoelectric switch for optical scanning; Setting a detection capability of the first output system by the user to a relatively low level and a detection capability of the second output system to a relatively high level; and upon receiving the outputs from the first and second output systems, causing an emergency stop of the hazard source when the safety signal from the first output system is received, and reducing its operating speed when the safety signal from the second output system is received.

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