JP2006236848A - Sensor head for reflection type photoelectric switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor head for a reflection type photoelectric switch capable of reducing the size thereof while keeping performance. <P>SOLUTION: This sensor head for a reflection type photoelectric switch is provided with a light-emitting element 12 and a light-receiving element 52, and is capable of detecting an object by projecting light to the object by the light-emitting element 12 and by receiving reflected light by the light-receiving element 52. The sensor head is provided with: a head case 71 constituting the sensor head; a main circuit board 140 incorporated in the head case 71; a light-projecting circuit 14 connected to the light-emitting element 12 for driving the light-emitting element 12; a light-receiving circuit 54 connected to the light-receiving element 52 for driving the light-receiving element 52; and a head cable 300 electrically connected to the main circuit board 140 and including signal lines and power feed lines for connecting it to a controller 200. The sensor head is so structured that a light-projecting circuit block constituting at least a part of the light-projecting circuit 14 and a light-receiving circuit block constituting at least a part of the light-receiving circuit 54 are arranged on the main circuit board 140 by being structurally separated from each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sensor head for a reflective photoelectric switch.

  The photoelectric switch is a sensor that can detect a detection target in a non-contact manner, and is used to detect the presence or absence of an object moving on a production line of a factory. In general, the presence or absence of an object is determined by projecting light onto an object conveyance path and detecting reflected or transmitted light of the light. The transmissive photoelectric switch utilizes the fact that the amount of light received by the light receiving unit changes when the light projected from the light projecting unit is blocked by the object passing through the object detection region, and the presence of the object is determined from this change. be able to. The transmissive photoelectric switch includes a light projecting unit having a light emitting element such as an LED (light emitting diode) and a light receiving unit having a light receiving element such as a PD (photodiode). The light projecting unit and the light receiving unit are arranged to face each other, and a photoelectric sensor is formed between the light projecting unit and the light receiving unit.

  This type of photoelectric switch includes a transmission type, a diffuse reflection type, and a coaxial regression reflection type. Among them, the transmission type and the diffuse reflection type have a light projecting unit and a light receiving unit configured separately, whereas the coaxial regressive reflection type photoelectric switch is different from the type in which such a separate type is used. There is a type in which the light receiving portion and the light receiving portion are integrated. The integrated type has the advantage that the wiring is simplified compared to the separate type, and the detection distance is longer than that of the diffuse reflection type by arranging the sensor and the reflection plate to face each other with the detection object interposed therebetween. .

  As a light emitting element used for a light projecting portion of a photoelectric switch, an element using an LD (semiconductor laser) instead of an LED has been developed. LDs have better optical characteristics than LEDs. Photoelectric sensors using LDs have higher light intensity than LEDs, so the spot diameter is more visible and workability during installation can be improved. The advantage is that the spot can be narrowed because of the small size.

Such a reflective photoelectric sensor head is required to be miniaturized. For this purpose, many optical systems have been devised. However, the improvement of the optical system alone has a limit, and the size reduction cannot be said to be sufficient. Further, the assembly workability is deteriorated due to the downsizing, so that the productivity is also deteriorated. Further, positioning becomes difficult due to miniaturization, and variations in optical characteristics also become a problem. In particular, conventionally, a holder for holding a light emitting element, a light receiving element, a lens and the like is provided, positioning is performed by the holder, and the holder is incorporated in the sensor head. However, when the holder is used, the case becomes larger by the thickness of the holder case. For example, the photoelectric sensor disclosed in Patent Document 1 has a configuration in which the holder shown in FIG. 15 is incorporated in the case shown in FIG. Further, in the example of the photoelectric sensor of Patent Document 2, since the holders as shown in the perspective view of FIG. 17 and the exploded perspective view of FIG. 18 are employed, a useless space is formed inside the case of the sensor head as shown in FIG. Will be occupied. Further, in the example of the photoelectric sensor of Patent Document 3, since the holder shown in FIG. 20 is used, similarly, as shown in FIG. 21, a useless space is occupied inside the case of the sensor head.
JP 2001-267594 A JP 2001-267626 A JP 2001-264608 A

  The present invention has been made to solve such problems. The main object of the present invention is to provide a sensor head for a reflective photoelectric switch that can be downsized while maintaining performance.

  In order to achieve the above object, a first reflective photoelectric switch sensor head according to the present invention includes a light emitting element and a light receiving element, and the light emitting element projects light onto an object, and reflected light. A sensor head for a reflective photoelectric switch that can detect an object by receiving light with a light receiving element, and is connected to a head case constituting the sensor head, a main circuit board built in the head case, and a light emitting element A light projecting circuit for driving the light emitting element, a light receiving circuit connected to the light receiving element, a signal receiving circuit for driving the light receiving element, a signal line electrically connected to the main circuit board, and connected to the controller; A head cable including a power supply line, and a light projecting circuit block constituting at least a part of the light projecting circuit and a light receiving circuit block constituting at least a part of the light receiving circuit on the main circuit board. But it becomes disposed structurally separated. With this configuration, it is possible to improve the noise tolerance of the light projecting circuit and the light receiving circuit, to stabilize the operation and improve the reliability, and to reduce the noise countermeasure members. In particular, on the main circuit board, it is difficult to propagate noise from the light emitting side, which is likely to generate noise, to the light receiving side, which is susceptible to noise.

  The second reflective photoelectric switch sensor head of the present invention further includes a light emitting element substrate for connecting the light emitting element and the light projecting circuit block on the main circuit board, and the light emitting element substrate is a flexible substrate. It consists of With this configuration, even if the main circuit board receives a physical external force, the force transmitted to the light emitting element can be reduced by interposing the flexible substrate, and the shift of the optical axis can be suppressed. If the optical axis is deviated, the original performance of the photoelectric switch cannot be maintained and the operation may be hindered. However, such a situation can be avoided and a stable operation with high accuracy can be realized.

  Furthermore, in the third reflective photoelectric switch sensor head of the present invention, the light emitting element substrate also serves as a shield for electronic components built in the reflective photoelectric switch sensor head. With this configuration, various other noise immunity such as a light emitting element can be further improved, and noise reduction members can be reduced to contribute to downsizing and cost reduction.

  Furthermore, in the fourth reflective photoelectric switch sensor head of the present invention, the main circuit board is formed of a hard board. With this configuration, the mechanical strength of the circuit board can be increased and resistance to external force can be increased. Moreover, since it is more stable than the flexible substrate, the assemblability can be improved.

  Furthermore, the fifth reflective photoelectric switch sensor head of the present invention has a head case divided into a lower case and an upper case, for positioning and holding the optical system member in the lower case. Positioning ribs are integrally formed. Conventionally, the optical element or lens is positioned in the case in a state where it is incorporated in a holding member such as a holder. However, in this configuration, the number of parts increases, the variation in accuracy accumulates, and the accuracy itself deteriorates. It gets bigger. On the other hand, with the above-described configuration, the arrangement work of the optical system members can be simplified and positioning can be performed at the same time by the ribs, and the positioning work can be saved. Furthermore, by forming the positioning member integrally, variation can be suppressed and positioning accuracy can be improved. Moreover, by setting it as the structure which mounts each member in a lower case, each member can be obstruct | occluded with an upper case after mounting with respect to a lower case at the time of an assembly operation, and the assembly property is made easy.

  Furthermore, the sixth reflective photoelectric switch sensor head of the present invention is configured such that the lower case and the upper case are fixed to the head cable by a protruding portion formed in the vertical direction. In this way, the method of fixing the head cable and the head case is not a structure in which protrusions are formed on the top, bottom, left, and right, but a structure in which the protrusions are provided only in the vertical direction, thereby increasing the fixing strength with the cable head. While maintaining, the protruding members from the left and right sides can be omitted to reduce the thickness of the head case in the left-right direction, thereby reducing the size. Here, the vertical direction means the dividing direction of the upper and lower cases.

  The seventh reflective photoelectric switch sensor head of the present invention further includes a light receiving element substrate for connecting the light receiving element and the light receiving circuit block on the main circuit board, and the light receiving element is a pair of light receiving elements. The light receiving element substrate is connected to the light receiving element in a state in which the pair of light receiving element terminals are arranged in a direction substantially perpendicular to the main surface of the main circuit board. The terminal surfaces connected to each other are exposed to a surface substantially parallel to the main surface of the main circuit board. With this configuration, even if the light receiving element terminal of the light receiving element is arranged in a direction perpendicular to the mounting surface of the main circuit board, the terminal surface can be exposed in the horizontal direction. It is possible to match the direction, and the mounting work can be facilitated. In particular, since the direction of the light receiving element terminal can be substantially changed without bending the lead frame of the light receiving element, workability can be improved while avoiding a decrease in reliability due to breakage of the light receiving element terminal.

  Furthermore, in the eighth reflective photoelectric switch sensor head of the present invention, the light receiving element substrate has a pair of notches into which the pair of light receiving element terminals can be inserted, and a straight line connecting the pair of notches. A pair of terminal surfaces are formed on the end surface of the light receiving element substrate along a substantially orthogonal direction, and each terminal surface is electrically connected to a notch conductive surface having conductivity formed in the notch. With this configuration, even if the light receiving element terminal of the light receiving element is arranged in a direction perpendicular to the mounting surface of the main circuit board, the terminal surface can be exposed in the horizontal direction. It is possible to match the direction, and the mounting work can be facilitated.

  Furthermore, the ninth reflective photoelectric switch sensor head of the present invention further includes an indicator lamp for indicating the operation state of the sensor head, and the indicator lamp is mounted on both surfaces of the main circuit board. It is a mounting type LED. If the indicator lamp is formed of discrete parts, the sensor head becomes large. Therefore, miniaturization is attempted using surface mount components. However, surface mount LEDs generally have a small amount of light, and a sufficient amount of light for visual recognition can be obtained only on one side. Therefore, the above-described configuration is adopted so that the indicator lamp can be confirmed from either the upper surface side or the lower surface side of the main circuit board while maintaining the necessary light quantity. Thereby, the visibility of the indicator lamp can be improved from either the left or right or top and bottom of the sensor head, and the operation state can be easily confirmed.

  According to the sensor head for a reflection type photoelectric switch of the present invention, it is possible to achieve both downsizing and assembling by integrating components, and maintain performance by suppressing variations in optical characteristics. In addition, the cost can be reduced by improving the number of parts and assembly workability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a reflective photoelectric switch sensor head for embodying the technical idea of the present invention, and the present invention provides the reflective photoelectric switch sensor head as follows. Not specified. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It's just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing.

FIG. 1 shows a block diagram of a photoelectric switch in which a sensor head 100 for a reflective photoelectric switch according to an embodiment of the present invention is connected to a controller 200. In the photoelectric switch shown in this figure, the sensor head 100 and the controller 200 are connected by a head cable 300. The sensor head 100 constitutes a reflective photoelectric switch including the light projecting unit 10 and the light receiving unit 50. The light projecting unit 10 projects light onto the object, and the light receiving unit 50 receives the reflected light that is reflected by the light and returned, thereby detecting the object. The controller 200 outputs a predetermined pulse to the sensor head 100 in order to drive the sensor head 100. The light emitting element 12 is driven by the oscillation pulse emitted from the light projection power supply control circuit 22 by the control unit 40 and emits pulsed light toward an external detection target. The light reflected by the detection target is photoelectrically converted by the light receiving element 52, and sent to the control unit 40 through the light receiving element amplification circuit 56, the controller amplification circuit 68, and the A / D converter 79. Thus, detection in synchronization with the pulsed light is performed, and the detection signal is further converted into a DC signal or the like, and then output from the I / O circuit 42 as an ON / OFF signal representing the detection result.
(Light projector 10)

  The light projecting unit 10 includes a light emitting element 12 for projecting light and a light projecting circuit 14 for driving the light emitting element 12. As the light emitting element 12, an LED, an LD, or the like can be used. In particular, since the LD has a larger amount of light and higher directivity than the LED, the detection accuracy is improved by narrowing the spot diameter. Moreover, since the spot diameter irradiated from LD can be visually recognized, it is excellent also in the workability | operativity at the time of installation. Therefore, in this embodiment, an LD having excellent optical characteristics is used as the light emitting element 12. Further, the light projecting circuit 14 for driving the LD includes a light projecting APC circuit 16 and a monitor light receiving element 18 such as a monitor PD. The light projection APC circuit 16 supplies drive power for driving the LD to the LD, and controls so that the output of the LD, that is, the light emission amount becomes a predetermined value.

Further, the sensor head 100 includes an indicator lamp 20 for displaying a light emission amount, an operation state, and the like. The projection APC circuit 16 and the indicator lamp 20 are supplied with driving power from the projection power source control circuit 22 and the head indicator lamp power source control circuit 24 of the controller 200 via the projection power source line. On the other hand, the monitor PD is connected to the monitor signal amplification circuit 26, and sends the received light amount to the LD light emission amount monitor circuit 28 of the controller 200 via a monitor line included in the head cable 300. The monitor signal amplifying circuit 26 is a member for suppressing variations in the light receiving element 18 for monitoring, and is composed of a trimmer or the like. The LD emission amount monitor circuit 28 outputs the LD emission amount detected by the monitor PD to the control unit 40 after the analog signal is converted into a digital signal by the A / D converter 30. Accordingly, the control unit 40 controls the light projection power supply control circuit 22 so that the light emission amount becomes a predetermined value based on the light emission amount detected by the monitor PD, and adjusts the current amount of the light projection APC circuit 16 to adjust the LD. Perform feedback control to drive. In the example shown in FIG. 1, the light projection APC circuit 16 is connected to the LD and the monitor PD which is the light receiving element 18 for monitoring, and the monitor PD is adjacent to a position where light leaking from the LD can be received. The monitor PD can also be built in the LD package. Also, the main circuit board 140 on which the monitor signal amplifying circuit 26 and the light projection APC circuit 16 are mounted is a rigid substrate, so that the monitor signal amplification circuit board trimmer and the light projection APC circuit trimmer are connected to the LD. It can be easily adjusted in the state.
(Light receiving unit 50)

  On the other hand, the light receiving unit 50 includes a light receiving element 52 for receiving light and a light receiving circuit 54 for driving the light receiving element 52. As the light receiving element 52, a PD or the like can be used. The light receiving element 52 is connected to the light receiving element amplifying circuit 56, and the amount of light received by the light receiving element 52 is amplified by the light receiving element amplifying circuit 56, and is connected to the controller 200 side via a signal line included in the head cable 300. It is sent to the controller amplification circuit 68. The analog signal amplified by the controller amplifier circuit 68 is converted into a digital signal via the A / D converter 70 and input to the control unit 40. As a result, the amount of light received by the light receiving element 52 is detected on the controller 200 side to determine detection, and finally the determination result is output from the output of the I / O circuit 42. The I / O circuit 42 includes two outputs 1 and 2 and one input 1. The sensor head 100 includes a light receiving unit power supply circuit 58 for supplying driving power for the sensor head 100, and is connected to the head power supply circuit 60 of the controller 200 via the power supply line of the head cable 300. The head power supply circuit 60 is controlled by the control unit 40 of the controller 200.

  When a plurality of types of sensor heads can be connected to the controller, an identification function for identifying each sensor head can be provided. In the example of FIG. 1, the head identification circuit 62 is provided in the controller 200, the head identification circuit 62 is connected to the signal line to detect the identification signal of the sensor head 100, and the controller 40 is connected to the controller 40 via the A / D converter 64. By sending out, each sensor head 100 is identified by the control unit 40. In addition, the control unit can perform data communication with each sensor head and assign an identification number.

  As described above, the controller 200 sends the projection power control circuit 22, the head indicator power control circuit 24, the LD light emission monitor circuit 28, the controller amplification circuit 68, the head identification circuit 62, the head power circuit 60, etc. Is connected. The control unit 40 further includes a switch 44 connected to a storage unit 44 for storing various setting values and the like, a display circuit 46 for displaying information on the controller 200 side, and an operation unit as a user interface for accepting setting value adjustments. An input circuit 48 and an I / O circuit 42 for inputting / outputting to / from the outside are connected. The controller 200 also includes a controller power supply circuit 66 for driving these circuits. One or more sensor heads 100 are connected to the controller 200 having the above configuration via the head cable 300, the light projected by the light emitting element 12 is received by the light receiving element 52, the object is detected, and the result is output. To do.

Next, the sensor head will be described in detail with reference to FIGS. 2 is a perspective view showing an external appearance (head case 71) of the sensor head, FIG. 3 is a perspective view showing a state in which the upper case 72 is removed, and FIG. 4 further opens the light emitting element substrate 120 so that the main circuit board 140 can be seen. The perspective view which shows the state made to each is shown. 5 is an exploded perspective view of the sensor head, FIG. 6 is a perspective view showing a state in which the integrated lens 112 is set in the lower case 74, and FIG. 7 shows a state in which the light emitting element 12 and the optical filter 53 are further set. FIG. 8 is a perspective view showing a state in which the light emitting element substrate 120 is further connected, FIG. 9 is a view showing the appearance of the light receiving element 52, and FIG. 11 is a view of the light receiving element case in which the light receiving element substrate 130 is connected to the light receiving element 52. FIG. 12 is an exploded perspective view of FIG. 11, FIG. 13 is a perspective view of the light receiving element case 150 of FIG. 11 set in the lower case 74 of FIG. 8, and FIG. Plan views of the main circuit board 140 are respectively shown.
(Head case 71)

A head case 71 constituting the outer shape of the sensor head has a rectangular parallelepiped box shape as shown in FIG. 2, and a light emitting surface and a light receiving surface are formed on one surface in the longitudinal direction of the head case 71 (right side in FIG. 2). The head cable 300 is extended from the opposite other surface. Further, a step is provided at the corner on the side where the head cable 300 is provided, and a display surface 76 indicating the operation state of the sensor head is provided here. The display surface 76 notifies the user of the operation mode, lighting state, and the like of the light emitting element by turning on or blinking the indicator lamp 20 provided in the translucent cover 78. The distinction between the operation states can be realized by setting in advance a change in the light emission state such as a change in the blinking interval of the indicator lamp 20, a light emission intensity, or a color change. As will be described later, in the present embodiment, two surface-mount LEDs 21 are arranged so as to face the left and right sides (upper and lower surfaces in FIGS. 2 and 5) of the sensor head. By using a plurality of LEDs for the indicator lamp 20 in this way, the amount of light can be increased and the indicator lamp can be easily seen not only from the rear and top surfaces but also from the left and right sides behind the sensor head. The cover 78 may be transparent, or may be translucent such as milky white containing a scattering member in order to scatter light from the indicator lamp. Furthermore, it is preferable to arrange the indicator lamp on the rear end side of the sensor head regardless of whether the indicator lamp is provided in the light projecting head or the light receiving head. When the sensor head is installed and optical axis alignment is performed, it is often confirmed from the rear end side of the sensor head. In this case, the indicator lamp is preferably provided on the rear side of the sensor head or on the side close to the cable so that it can be confirmed with the indicator lamp that light is being projected and received correctly.
(Fixing of the head cable 300 and the head case 71)

  As shown in FIG. 5, the head case 71 is composed of an upper case 72 and a lower case 74 so as to be divided into two vertically. Further, in order to fix the head cable 300, the head cable 300 is fitted so that the upper case 72 and the lower case 74 are closely attached from above and below. The head cable 300 forms a cable bush 80 in which the end of the cable is fixed. As will be described later, various power supply lines and signal lines included in the head cable 300 are fixed to the main circuit board 140 by soldering or the like. For this reason, if the cable bushing is not sufficiently fixed to the sensor head, the main circuit board is also pulled when the head cable is pulled, causing a positional shift in the optical system such as a light emitting element and a light receiving element connected to the main circuit board. There is a fear. In the photoelectric switch, strict positioning is required in order to perform highly accurate detection, and the positional deviation of the optical system leads to a decrease in detection accuracy and reliability. For this reason, conventionally, fixing of the head cable has been performed from the four sides of the cable bush. As the fixing structure, a protrusion and an insertion hole for inserting the protrusion are used. However, this configuration requires a fixing structure around the cable bush, and there is a problem in that the entire end surface of the head case is enlarged. Therefore, in the present embodiment, in order to maintain the connection strength with the head cable while reducing the size of the sensor head, the cable bush is sandwiched from above and below and a fixing structure is formed. The fixing structure includes a protruding portion 82 and an insertion hole 84 for inserting the protruding portion 82. In the example of FIG. 5, a pair of projecting portions 82 projecting in the vertical direction are formed on the cable bush 80 side, and the insertion holes 84 of the projecting portions 82 are formed at corresponding positions of the upper and lower cases 72 and 74. The part 82 is inserted into the insertion hole 84 and fitted. However, it is needless to say that a protruding portion can be formed on the upper and lower case sides and an insertion hole can be formed on the cable bush side, and that one or more protruding portions and insertion holes can be formed on the upper and lower surfaces. Here, the vertical direction means the dividing direction of the upper and lower cases 72 and 74. Accordingly, when the upper and lower cases 72 and 74 are fitted, the fixing structure of the head cable 300 can be fitted at the same time, and workability is improved.

Further, a flange 86 protruding toward the cable bush 80 is formed at the opening end of the upper and lower cases 72 and 74 where the head cable 300 is connected, and a groove 88 for inserting the flange 86 is formed in the cable bush 80. Thus, the cable bush 80 and the head case 71 can be further firmly fixed by this holding structure. Furthermore, such a holding structure can be provided not only on the upper and lower sides but also on the left and right sides. In the example of FIG. 5, the display surface 76 is formed at the corner of the rear end surface of the head case 71 to which the head cable 300 is connected. Instead, the cover 78 can be used for fixing the cover 78 by inserting the cover 78 into the groove formed in this portion with the edge of the cover 78 having a hook shape.
(Positioning of optical system members)

  The lower case 74 is integrally formed with a positioning rib 90 for positioning and holding the optical system member. As described above, in a photoelectric switch, positioning of optical members such as a light emitting element and a light receiving element is extremely important in order to perform highly accurate detection. However, since each optical system member is conventionally configured in a unit shape, such as being set in an element holder, an inner case, etc., and then fixed to the head case, there are variations in optical characteristics due to dimensional errors of the element holder, etc. Arise. In addition, the use of the element holder as a separate member causes an assembling error as well as an increase in assembly man-hours due to an increase in the number of parts and a cost increase. Therefore, in this embodiment, a positioning rib 90 is formed integrally with the lower case 74 so that the optical system member is fixed at a predetermined position in advance without using a separate member such as an element holder. The case itself is configured to also serve as an element holder. As a result, the optical system member can be positioned at the same time by arranging the optical system members at the positions defined by the ribs 90, so that laborious positioning work can be saved. The positioning rib 90 is preferably provided for a light emitting element that requires the highest positioning accuracy among the optical members. In the example of FIGS. 6 and 7, the LD positioning rib 92 is formed so that the LD which is the light emitting element 12 is arranged. As another method, when more precise positioning is desired, the LD may be fixed using a UV adhesive or the like after adjusting the position of the LD in the XYZ axial directions. The LD positioning rib 92 has a horizontal cross section with a stepped shape so as to sandwich the cylindrical side surface of the shell-type LD and the flange-shaped portion of the bottom surface of the LD. Further, the LD positioning rib 92 positions the projection slit 93 and the integral lens 112. By thus forming the LD positioning rib 92 so as to coincide with the outer shape of the light emitting element 12, the light emitting element 12 can be reliably held and accurately positioned. The LD positioning rib 94 facing the light emitting surface of the LD has an opening for allowing light to pass therethrough.

  In addition, PD positioning ribs 96 are also formed at positions where the light receiving element case 150 in which the PD that is the light receiving element 52 is set is set. Such a PD positioning rib 96 allows the light receiving element 52 to be arranged at an accurate position, thereby suppressing variations in optical characteristics. A light receiving slit 110 for determining a light receiving spot is formed in the PD positioning rib 98 facing the light receiving surface of the PD. In this way, the light receiving slit 110 for determining the light receiving spot is not formed as a separate member, but is formed as a single member, so that the positioning operation can be saved and the variation among individuals can be reduced, thereby realizing a high-quality sensor head. Further, the lenses for the light emitting element and the light receiving element are also positioned and fixed by the positioning rib 90. In this example, in order to suppress variation in the mutual position between the light projecting and receiving light, the integral lens 112 in which the light projecting lens 112a and the light receiving lens 112b are integrally molded is used, but individual members can also be used. Needless to say.

  In addition to the lens, the slit is an optical element that determines the field of view of the light projecting / receiving system. In this embodiment, the integrated lens 112 is fitted into the lower case 74 so that the optical members such as the light projecting slit 93, the light receiving slit 110, the light projecting lens 112a, and the light receiving lens 112b can be positioned. More specifically, the arrangement of the light projecting lens 112 a and the light receiving lens 112 b is suppressed by using the integrated lens 112. Further, the arrangement of the light projecting slit 93 and the light receiving slit 110 is controlled by forming them integrally in the lower case 74. Further, the light projecting lens 112 a and the light projecting slit 93 are positioned by the lower case 74. Furthermore, the light receiving lens 112 b and the light receiving slit 110 are also positioned by the lower case 74. Since the light emitting element 12 has a large variation in the light emitting position, it is difficult to uniformly position the light emitting element 12 with a positioning member or the like. Therefore, the light emitting element 12 is individually adjusted and fixed by bonding or the like. On the other hand, since the light receiving element 52 has a larger light receiving surface so as to widely correspond to the light receiving position that varies depending on the distance between the detection target and the sensor head, positioning accuracy is not required so strictly.

As described above, the positioning rib 90, partitions, and the like are formed in the lower case 74, and the side wall of the head case 71 is formed on the upper case 72 side as shown in FIG. By not providing a side wall in the lower case 74, the mounting space is opened to improve workability, and the upper case 72 is closed after the work is completed to form the side wall at the same time. The upper case 72 is formed in a U-shaped cross section that opens in the lower direction to be fitted to the lower case 74.
(Light emitting element substrate 120)

The light emitting element 12 is connected to the main circuit board 140 through the light emitting element substrate 120. The light emitting element substrate 120 is a substrate on which electronic members and the like constituting the light projecting circuit 14 are mounted. In this example, only a function as a cable connecting the LD and the main circuit board is provided, but a power supply circuit of the LD can be mounted by printing. The light emitting element substrate 120 is preferably composed of a flexible substrate. Further, the light emitting element substrate may be constituted by two or more flexible substrates. As described above, since it is necessary to strictly position the light emitting element and the lens, in the case of a hard substrate, it is necessary to suppress the influence of external force so that the light emitting element is not displaced during use. If the light emitting element is directly fixed to the main circuit board by soldering or the like, the position of the light emitting element may be shifted when a physical external force is applied to the main circuit board by pulling the head cable or the like. Even if the positional deviation of the light emitting element is small, it affects the detection accuracy of the optical sensor, and the optical axis is misaligned, so the performance cannot be maintained. Therefore, by interposing a flexible substrate between the light emitting element and the main circuit board, cushioning can be provided to improve impact resistance, and even if an external force is applied, force can be prevented from being transmitted to the light emitting element. Therefore, reliability can be improved by avoiding optical displacement. In the example of FIG. 8, the light emitting element substrate 120 has a bent piece 122 that is bent substantially perpendicularly at one end, and an insertion port 124 into which the LD terminal group of the LD is inserted is formed in the bent piece 122. Preferably, a light emitting element spacer 126 is interposed between the light emitting element 12 and the bent piece 122. The light-emitting element spacer 126 is used for the purpose of bending the terminal of the light-emitting element 12 so as to be easily joined to the bent piece 12. The light emitting element spacer 126 is intended for thermal protection during LD soldering.
(shield)

  Further, the light-emitting element substrate 120 can also be used as a shield for electronic components incorporated in the reflective photoelectric switch sensor head. The shield may be formed integrally or separately. In order to stabilize the operation of the reflective photoelectric switch sensor head, it is desirable that the electronic components that drive the light-emitting element 12 and the light-receiving element 52 take some noise countermeasures to block the influence of external disturbances such as noise. It is. However, if a shield member or the like is prepared separately, it is costly and leads to enlargement of the sensor head size. Therefore, in the present embodiment, the light emitting element substrate is also used as a shield for the electronic circuit. By disposing the light emitting element substrate 120 so as to be folded on the main circuit board 140, the main circuit board 140 can be protected from disturbance. In particular, when the light-emitting element substrate 120 is a flexible substrate, an advantage that such a folding arrangement can be easily obtained is obtained. In the present embodiment, the configuration shown in FIGS. 3 and 4 is adopted in order to realize such a shield. 4 shows a state in which the light emitting element 12 and the light receiving element 52 are connected to the main circuit board 140 through the light emitting element substrate 120 and the light receiving element substrate 130, respectively. FIG. The state where the light emitting element substrate 120 is folded and overlapped on the upper surface is shown. As shown in these drawings, the light emitting element substrate 120 is bent at two places to realize connection with the light emitting element 12 and folding onto the main circuit board 140.

  The light emitting element substrate 120 is formed in an L shape in which a bent piece 122 for obtaining connection with the light emitting element 12 is projected from one end. The bent piece 122 is formed in a size that allows the light emitting element terminal group of the light emitting element 12 to be inserted. In addition, a GND pattern of an electronic component is formed on the entire surface, and is also used as a shield surface. In the present embodiment, as shown in FIGS. 4 and 13, the light emitting element 12 is connected by bending the bent piece 122 substantially vertically. In the present specification, the term “bent” is used to include a curved state, and it is preferable to bend, particularly when a flexible substrate is used. As a result, the curved portion serves as a buffering function and separates the positional deviation of the main circuit board 140 from the light emitting element 12.

The light emitting element substrate 120 is preferably arranged along the inner wall of the head case 71 in order to shield the electronic components inside the head case 71. Therefore, in the present embodiment, the light emitting element substrate 120 is bent so as to continue from one side surface of the upper case 72 to the upper surface as shown in FIG. Thereby, the inside of the head case 71 can be shielded from the side surface to the upper surface. For this reason, the light emitting element substrate 120 is bent from the state in which the light emitting element substrate 120 is erected almost perpendicularly to the side surface of the lower case 74 on the side where the LD is disposed as shown in FIG. In the state where the main circuit board 140 is connected to the light-emitting element substrate 120 and the light-receiving element substrate 130 as shown in FIG. To do. Bending can be easily performed by setting the folding position to the position where the bent piece 122 is provided, that is, the L-shaped corner position. Therefore, the size and position of the bent piece 122 are designed according to the position where the shield surface is formed, in addition to the shape of the light emitting element terminal of the light emitting element 12 and the like.
(Light receiving element 52)

  The light receiving element 52 can be composed of a PD or the like. Further, an optical filter 53 or the like can be disposed on the front surface of the PD as necessary. In the example of FIG. 7, a filter holding groove 114 that holds the optical filter 53 is formed on the front surface of the rib 90 in which the light receiving slit 110 is formed. FIG. 9 shows the appearance of the PD used in this embodiment. 9A is a plan view of the PD, FIG. 9B is a perspective view, FIG. 9C is a front view, and FIG. 9D is a side view. FIG. 10 shows a state in which the sensor head in which the light emitting element 12 and the light receiving element 52 are arranged is viewed from above, and the reflected light of the light emitted from the light emitting element 12 depends on the distance between the sensor head and the detection target. 5 is a schematic diagram showing how the position received at 52 changes. FIG. As shown in FIG. 10, the further away the detection target is from the sensor head, the closer the reflected light gets to the light emitting element 12, and the light is received by the upper part of the light receiving element 52 in FIG. Conversely, as the detection target is closer to the sensor head, the reflected light is received at a position farther from the light emitting element 12, and is received at the lower part of the light receiving element 52 in FIG. Therefore, in order to detect a detection target in a wide range from a short distance to a long distance by the photoelectric sensor, the light receiving range of the light receiving element 52 is given a width, and this width is the separation direction of the light receiving element 52 and the light emitting element 12. That is, in FIG. 10, it is necessary to arrange it so as to be vertically long so as to be horizontal with respect to the head case 71.

  On the other hand, from the viewpoint of reducing the size of the photoelectric sensor, it is desirable to reduce the size of the light receiving element 52. As shown in FIG. 9, the PD which is one form of the light receiving element 52 is provided so that a pair of light receiving element terminals (PD terminals 116) such as a lead frame protrude. In general, the PD is formed by connecting a light receiving chip constituting a light receiving surface of the PD to the PD terminal 116 by wire bonding or the like, and sealing the light receiving chip with a casting mold or a transfer mold. In such a PD, as shown in the front view of FIG. 9C, in order to achieve downsizing while taking a wide light receiving surface in one direction, PD terminals 116 are provided above and below the light receiving chip constituting the light receiving surface. It is desirable to arrange. As a result, due to the optical characteristics of the light receiving element, when the light receiving surface is arranged horizontally and disposed in the head case 71 as shown in FIG. 10, the pair of PD terminals 116 are disposed vertically in the head case 71. The vertically placed PD terminal group has a problem that the mounting work with the main circuit board 140 becomes troublesome. In order to facilitate mounting, it is conceivable to bend the lead frame to change the direction or to pull it out. Therefore, in the present embodiment, even if the PD terminal 116 is vertical using the light receiving element substrate 130, specifically, it is electrically connected to the PD terminal 116 so as to be horizontal on the lower case 74. The terminal surface 132 is changed so as to be exposed on the main circuit board 140. As a result, the orientation of the PD terminal 116 can be changed without bending, and the PD terminal 116 can be pulled out to a position where it can be easily mounted. Can be improved.

Further, since a PD in which a PD resin mold is formed by a casting mold can be used, there is an advantage that the cost of the PD can be reduced. The casting mold is advantageous in terms of cost because it can use an inexpensive mold as compared with the transfer mold. Further, in order to reduce the size of the sensor head, it is necessary to reduce the area in the front view of the PD as much as possible while widening the light receiving surface as shown in FIG. 9C. In general-purpose transfer mold type PD, In the front view, the lead frame protrudes up and down or left and right. Although it is possible to customize the transfer mold type, an expensive mold is required in this case. Therefore, there is an advantage that the cost can be reduced by using the casting mold PD.
(Light receiving element substrate 130)

The light receiving element substrate 130 is formed of a hard substrate such as a glass epoxy substrate. Moreover, electronic parts etc. can also be mounted as needed. FIG. 11 is an external perspective view showing a state in which the light receiving element 52 and the light receiving element substrate 130 are set in the light receiving element case 150, and FIG. 12 is an exploded perspective view showing the light receiving element substrate 130, the light receiving element 52, and the light receiving element case 150. Are shown respectively. As shown in these drawings, the light receiving element substrate 130 forms a pair of notches 134 into which the PD terminals 116 can be inserted. In the example of FIG. 12, the notch 134 is provided with U-shaped opposing side surfaces of the light receiving element substrate 130, and an end along the notch 134 on the inner surface of the notch 134 or the upper surface of the light receiving element substrate 130. A notch conductive surface 136 such as conductive plating having conductivity is formed on the edge. Further, a pair of terminal surfaces 132 for connecting the PD terminal 116 electrically connected by the notch 134 to the main circuit board 140 is formed. The pair of terminal surfaces 132 are formed so as to be substantially orthogonal to the pair of notches 134. In the example of FIG. 12, the terminal surface 132 is formed on the side surface where one notch 134 is formed so as to sandwich the notch 134. The terminal surface 132 is formed with a conductive surface such as conductive plating in a rectangular shape extending from the edge of the light receiving element substrate 130. Each terminal surface 132 is electrically connected to a notch conductive surface 136 having conductivity formed in the notch 134. As a result, the PD terminal 116 can be taken out from one side surface of the light receiving element substrate 130, and the connection operation with the main circuit substrate 140 can be easily performed by making this surface upward. In the example of FIG. 12, the notch 134 is provided at the center of the light receiving element substrate 130, but may be provided at the end.
(Light receiving element case 150)

In the example of FIG. 12, a light receiving element case 150 that holds the light receiving element 52 and the light receiving element substrate 130 is used. The light receiving element case 150 shields the PD and the light receiving circuit 54, and also serves as a support member for the main circuit board 140 in the example of FIG. In the light receiving element case 150 shown in this figure, a light receiving element insertion portion 152 for inserting the light receiving element 52 is formed at the tip, and a rib 154 for supporting the main circuit board 140 is formed at the rear. The light receiving element case 150 is inserted into the light receiving element case 150 with the light receiving element substrate 130 connected to the PD that is the light receiving element 52, and the light receiving element case 150 is set in the lower case 74 as shown in FIG. As shown in FIG. 11, the light receiving element case 150 holds the light receiving element 52 and the light receiving element substrate 130, and protects the light receiving element 52 and / or the light receiving circuit 54 from disturbances such as noise. The light receiving element case 150 is preferably made of a metal such as aluminum. In addition, by making it metal, the main circuit board 140 can be held with sufficient strength even if the case thickness is reduced, which can contribute to the downsizing of the sensor head, and also provides a shielding effect by itself. The effect of improving heat dissipation is also obtained. In particular, the light receiving element insertion portion 152 effectively functions not only as a positioning of the light receiving element 52 but also as a shield by covering the periphery of the light receiving element 52 inserted into the opening.
(Main circuit board 140)

  The main circuit board 140 mounts the light projecting circuit 14 and the light receiving circuit 54 and is electrically connected to the light emitting element 12 via the light emitting element substrate 120 and the light receiving element 52 via the light receiving element substrate 130. . The main circuit board 140 is structured such that the light projecting circuit block and the light receiving circuit block are structurally separated from each other, so that the interference between the circuits can be reduced and operated stably. In the example shown in FIG. 14, the light receiving circuit block 142 is disposed on the right side, and the light projecting circuit block 144 is disposed on the left side, and the light receiving element substrate connection terminal surface 146 for connection to the light receiving element substrate 130 is disposed on the light receiving circuit block 142. A light emitting element substrate connection terminal surface 148 for connecting the light emitting element substrate 120 to the circuit block 144 is formed. Further, a head cable connection terminal surface 149 for connecting the head cable 300 is formed in the lower part of the main circuit board 140, and in this example, there are six terminal surfaces corresponding to the six-core electric signal lines. . At the time of mounting, the connection terminal surfaces are directly soldered to electrically connect the substrates. By connecting directly without interposing a lead wire or the like, the number of parts and processes can be reduced and the cost can be reduced.

The main circuit board 140 can be a hard board. As the hard substrate, a glass epoxy substrate, a ceramic substrate, an aluminum substrate, or the like can be used. In general, the flexible substrate is expensive, and because it is a flexible material, the assemblability is poor and positioning becomes difficult. On the other hand, a hard substrate is inexpensive and easy to position, and has good workability during assembly. The main circuit board can be composed of a single hard board. This can reduce the number of mounted parts, further improving productivity. However, it is also possible to configure the main circuit board with a flexible board. Miniaturization can be realized by using a flexible substrate. In the example shown in FIG. 14, a double-sided substrate is used, and the light-receiving unit power circuit 58 of the light-receiving circuit block 142 is placed on the front surface of the substrate (on the right side in FIG. 14C). The amplifier circuit of the light receiving circuit block is arranged on the left side in Fig. 14. Similarly, for the light projecting circuit block 144, the current adjustment circuit is on the front side (left side in Fig. 14C), and the other circuits are on the back side (Fig. In this way, by physically separating the light projecting circuit 14 and the light receiving circuit 54, noise resistance can be improved and more stable operation can be expected. Coupled with the configuration in which the upper surface of the main circuit board 140 is shielded by the light emitting element substrate 120, noise resistance can be further improved, and in order to enhance the shielding effect by the light emitting element substrate 120, a light receiving element case. 50 is formed of a sheet metal part, and is preferably connected to a shield sheet metal connection terminal 141 formed on the main circuit board 140 to be a ground level, and the light receiving element case 150 integrally shields the PD and the light receiving circuit. The structure reduces the size and improves the workability during assembly, as shown in Fig. 4. With the main circuit board 140 set, the light receiving element substrate connecting terminal surface 146 and the light emitting element substrate connecting terminal surface are assembled. 148, the four points of the head cable connection terminal surface 149 and the shield sheet metal connection terminal 141 are soldered.
(Indicator light 20)

  Further, a notch 134 is formed in a part of the main circuit board 140 in order to dispose the indicator lamp board on which the indicator lamp 20 for indicating the operation state of the sensor head is mounted. The indicator lamp 20 has surface-mounted LEDs 21 mounted on both sides of the indicator lamp substrate. In the example of FIG. 14, the display lamp 20 is integrated with the main circuit board 140 to reduce the size, but the display lamp 20 can be mounted on another board.

  In this way, by integrating the components of the sensor head of the reflective photoelectric switch, both miniaturization and assemblability can be achieved, and variations in optical characteristics can be suppressed to maintain performance. In particular, mounting the element members constituting each circuit on a flexible board requires a lot of man-hours and high costs. However, the substrate on which the element members are mounted is a single hard board, and the circuit elements are mounted on the flexible board. First, it can be miniaturized at the lowest cost by functioning only as a cable or wiring. In addition, parts related to each of the light emitting circuit and the light receiving circuit are independently arranged to increase noise resistance, thereby reducing unnecessary parts for noise countermeasures and saving space. . In addition, assembling is facilitated by arranging all the component holding portions in the lower case.

  The sensor head for a reflective photoelectric switch of the present invention can be suitably used for a photoelectric sensor or the like that detects the presence or absence of an object in a production line of a factory.

It is a block diagram which shows the photoelectric switch which connected the sensor head for reflective photoelectric switches which concerns on one embodiment of this invention to the controller. It is a perspective view which shows the external appearance of a sensor head. It is a perspective view which shows the state which removed the upper case from FIG. FIG. 4 is a perspective view showing a state where a light emitting element substrate is opened from FIG. 3 so that a main circuit board can be seen. It is a disassembled perspective view which shows a sensor head. It is a perspective view which shows the state which set the integrated lens to the lower case. It is a perspective view which shows the state which set the light emitting element further to the lower case of FIG. It is a perspective view which shows the state which connected the light emitting element board | substrate to FIG. It is a figure which shows the external appearance of a light receiving element. It is a schematic diagram which shows a mode that the position where reflected light is received changes according to the distance of a sensor head and a detection target. The perspective view which shows the state which connected the light receiving element board | substrate to the light receiving element, and was set to the light receiving element case It is a disassembled perspective view which shows the light receiving element of FIG. 11, a light receiving element board | substrate, and a light receiving element case. It is a perspective view which shows the state which set the light receiving element case of FIG. 11 to the lower case of FIG. It is the bottom view, side view, and top view which show a main circuit board. It is a perspective view which shows the holder used for the sensor head of the conventional photoelectric sensor. It is a perspective view which shows the case of the sensor head incorporating the holder of FIG. It is a partially cutaway perspective view showing a holder of another conventional photoelectric sensor. It is a disassembled perspective view of the holder of FIG. It is sectional drawing which shows arrangement | positioning inside the case of the sensor head incorporating the holder of FIG. It is sectional drawing which shows the holder of the other conventional photoelectric sensor. It is a cross section which shows arrangement | positioning inside the case of the sensor head incorporating the holder of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Sensor head; 200 ... Controller; 300 ... Head cable 10 ... Light emitting part 12 ... Light emitting element 14 ... Light emitting circuit 16 ... Light emitting APC circuit 18 ... Light receiving element for monitoring 20 ... Indicator light 21 ... Surface mount type LED
DESCRIPTION OF SYMBOLS 22 ... Light projection power supply control circuit 24 ... Head indicator light power supply control circuit 26 ... Monitor signal amplification circuit 28 ... LD light emission amount monitor circuit 30 ... A / D converter 40 ... Control part 42 ... I / O circuit 44 ... Memory | storage part 46 ... Display circuit 48 ... Switch input circuit 50 ... Light receiving portion 52 ... Light receiving element 53 ... Optical filter 54 ... Light receiving circuit 56 ... Light receiving element amplification circuit 58 ... Light receiving portion power supply circuit 58
DESCRIPTION OF SYMBOLS 60 ... Head power supply circuit 62 ... Head identification circuit 64, 70 ... A / D converter 66 ... Controller power supply circuit 68 ... Controller amplifier circuit 71 ... Head case 72 ... Upper case 74 ... Lower case 76 ... Display surface 78 ... Cover 80 ... Cable bush 82 ... Projection part 84 ... Insertion hole 86 ... ８８ 88 ... Groove 90 ... Positioning rib 92 ... LD positioning rib 93 ... Projection slit 94 ... LD positioning rib 96 ... PD positioning rib 98 ... PD positioning rib DESCRIPTION OF SYMBOLS 110 ... Light receiving slit 112 ... Integrated lens 112a ... Light projection lens 112b ... Light receiving lens 114 ... Filter holding groove 116 ... PD terminal 120 ... Light emitting element substrate 122 ... Bending piece 124 ... Insertion port 126 ... Light emitting element spacer 130 ... Light receiving element substrate 132 ... Terminal surface 134 ... Notch 136 ... Notch conductive surface 140 ... Circuit board 141 ... Shield sheet metal connection terminal 142 ... Light receiving circuit block 144 ... Light projecting circuit block 146 ... Light receiving element board connecting terminal face 148 ... Light emitting element board connecting terminal face 149 ... Head cable connecting terminal face 150 ... Light receiving element case 152 ... Light receiving Element insertion part 154 ... rib

Claims (9)

A reflective photoelectric switch sensor head comprising a light emitting element and a light receiving element, wherein the light emitting element projects light onto an object and receives the reflected light by the light receiving element. There,
A head case constituting the sensor head;
A main circuit board built in the head case;
A light projecting circuit connected to the light emitting element for driving the light emitting element;
A light receiving circuit connected to the light receiving element for driving the light receiving element;
A head cable that is electrically connected to the main circuit board and includes a signal line and a power supply line for connecting to the controller;
With
On the main circuit board, a light projecting circuit block constituting at least a part of the light projecting circuit and a light receiving circuit block constituting at least a part of the light receiving circuit are structurally separated from each other. A sensor head for a reflective photoelectric switch. The reflective photoelectric switch sensor head according to claim 1, further comprising:
Comprising a light emitting element substrate for connecting the light emitting element and a light projecting circuit block on the main circuit board;
The sensor head for a reflective photoelectric switch, wherein the light emitting element substrate is formed of a flexible substrate. The reflective photoelectric switch sensor head according to claim 2, further comprising:
The light emitting element substrate is also used as a shield for an electronic component built in the sensor head for a reflective photoelectric switch. A sensor head for a reflective photoelectric switch according to any one of claims 1 to 3,
The sensor head for a reflective photoelectric switch, wherein the main circuit board is formed of a hard board. A sensor head for a reflective photoelectric switch according to any one of claims 1 to 4,
The head case is divided into a lower case and an upper case,
A sensor head for a reflective photoelectric switch, wherein a positioning rib for positioning and holding an optical system member is integrally formed on the lower case. A sensor head for a reflective photoelectric switch according to claim 5,
A sensor head for a reflective photoelectric switch, wherein the lower case and the upper case are configured to be fixed to the head cable by a protruding portion formed in a vertical direction. The reflective photoelectric switch sensor head according to any one of claims 1 to 6, further comprising:
A light receiving element substrate connecting the light receiving element and the light receiving circuit block on the main circuit board;
The light receiving element includes a pair of light receiving element terminals,
The light receiving element substrate is connected to the light receiving element in a state in which the pair of light receiving element terminals are arranged in a direction substantially perpendicular to the main surface of the main circuit board, and is electrically connected to the pair of light receiving element terminals. A sensor head for a reflective photoelectric switch, characterized in that the terminal surface thus formed is exposed to a surface substantially parallel to the main surface of the main circuit board. A sensor head for a reflective photoelectric switch according to claim 7,
The light receiving element substrate forms a pair of notches into which the pair of light receiving element terminals can be inserted;
Forming a pair of terminal surfaces on an end surface of the light receiving element substrate along a direction substantially orthogonal to a straight line connecting the pair of notches,
A sensor head for a reflective photoelectric switch, wherein each terminal surface is electrically connected to a notch conductive surface having conductivity formed in the notch. The reflective photoelectric switch sensor head according to any one of claims 1 to 8, further comprising:
It is equipped with an indicator light to indicate the operating state of the sensor head,
A sensor head for a reflective photoelectric switch, wherein the indicator lamp is a surface-mounted LED mounted on both surfaces of the main circuit board.

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