Photoelectric separated detector and method for adjusting the optical axis of the photoelectric separated detector

Abstract

To provide a photoelectric separation type sensor and an optical axis adjustment method of the photoelectric separation type sensor which is suitable when a waterproof specification is applied and also which can realize highly accurate optical axis adjustment.SOLUTION: In a photoelectric separation type sensor, an optical transmitter 1 having a light emitting element 3 and an optical receiver having a light receiving element are arranged to be opposed inside a monitoring space. At least one of the optical transmitter 1 and the optical receiver includes optical axis adjustment means 7. The optical axis adjustment means 7 comprises: a plurality of lenses including a convex lens whose lens center is set at a position deviated from an optical axis of the light emitting element 3 or the light receiving element; and lens rotation means 11 for rotating at least two lenses including the convex lens around each rotation axis deviated from the respective lens centers at different rotation speeds.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photoelectric separated sensor in which a light transmitter having a light emitting element and a light receiver having a light receiving element are arranged opposite each other in a monitored space, and to a method for adjusting the optical axis of the photoelectric separated sensor. [Background technology]

[0002] A photoelectric separated detector detects fires by placing a light transmitter containing a light-emitting element and a light receiver containing a light-receiving element opposite each other at a high altitude (usually 10 to 15 m above ground) and a monitoring distance of usually 5 to 100 m between the light transmitter and receiver, and detecting the attenuation of light due to the presence of smoke between the light transmitter and receiver. Since the light transmitter and receiver are installed at a long distance apart, adjustment is required to align the optical axes of the light transmitter and receiver.

[0003] For this reason, the photoelectric separated type detector is provided with an optical axis adjusting means for adjusting the optical axis. For example, the photoelectric separation type sensor disclosed in Patent Document 1 has, as an optical axis adjustment means, an angle adjustment screw for adjusting the angle of the optical bench that houses the light-emitting element (light-receiving element), and a sighting hole for visually checking the position of the opposing element using a reflecting mirror.

[0004] In the optical axis adjustment in Patent Document 1, the worker rotates the angle adjustment screw to roughly adjust the angle of the optical bench so that the opposing object is visible in the collimation hole reflected in the reflector, and then makes further fine adjustments while checking whether the specified output is being obtained on the receiver side. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-59784 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the optical axis adjustment in Patent Document 1 requires removing the cover covering the optical table at the installation site, making it difficult to make the photoelectric separated sensor waterproof. Furthermore, it is preferable to adjust the angle of the optical bench so that the amount of light received by the receiver is as large as possible, but because the worker adjusts the angle while checking the amount of light received, it is not possible to know during the adjustment whether the angle is the angle at which the amount of light received is maximum, and it is necessary to reset the angle to the angle at which the amount of light received was maximum after completing the adjustment work.This makes the work complicated and makes it difficult to make accurate adjustments.

[0007] The present invention has been made to solve the above problems, and aims to provide a photoelectric separated type sensor and a method for adjusting the optical axis of a photoelectric separated type sensor that are suitable for use in waterproof specifications and that can achieve high-precision optical axis adjustment. [Means for solving the problem]

[0008] (1) The photoelectric separated sensor of the present invention comprises a light transmitter having a light emitting element and a light receiver having a light receiving element, which are arranged opposite each other in a monitored space, and at least one of the light transmitter or the light receiver is provided with an optical axis adjustment means, which is characterized by having a plurality of lenses including a convex lens whose lens center is positioned at a position offset from the optical axis of the light emitting element or the light receiving element, and a lens rotation means which rotates at least two lenses including the convex lens at different rotation speeds around rotation axes offset from the respective lens centers.

[0009] (2) In the above (1), the lens rotating means rotates the plurality of lenses around the optical axis as a rotation axis.

[0010] (3) Furthermore, the optical axis adjustment method for a photoelectric separated sensor according to the present invention is a method for adjusting the optical axis of a photoelectric separated sensor as described in (1) or (2) above, characterized in that the plurality of lenses are rotated and the optimal positions of the plurality of lenses are determined based on the amount of light received by the light receiver.

[0011] (4) Furthermore, in the device described in (3) above, the position of the plurality of lenses before rotation is set as an initial position, and after the rotation is performed until the lenses return to the initial position, the position of the plurality of lenses when the amount of received light is greatest is identified as the optimal position of the plurality of lenses, and the plurality of lenses are positioned at the optimal position.

[0012] (5) Furthermore, the optical axis adjustment method for a photoelectric separated sensor according to the present invention is a method for adjusting the optical axis of a photoelectric separated sensor, which comprises a light transmitter having a light-emitting element and a light receiver having a light-receiving element, arranged opposite each other in a monitored space, and is characterized in that at least two lenses, including a convex lens provided in the light transmitter and / or the light receiver, and whose lens center is positioned at a position offset from the optical axis of the light-emitting element or the light-receiving element, are rotated around rotation axes offset from the respective lens centers at different rotation speeds, and the optimal position of the lens is identified based on the amount of light received by the light receiver.

[0013] (6) Furthermore, in the device described in (5) above, the position of at least two lenses including the convex lens before rotation is set as an initial position, and after the rotation is performed until the lenses return to the initial position, the position of the lenses when the amount of received light is greatest is identified as the optimal position of the lenses, and the lenses are positioned at the optimal position.

[0014] (7) The photoelectric separated sensor of the present invention is a photoelectric separated sensor comprising a light transmitter having a light emitting element and a light receiver having a light receiving element, arranged opposite each other in a monitored space, and at least one of the light transmitter or the light receiver is provided with an optical axis adjustment means, the optical axis adjustment means comprising a convex lens whose lens center is positioned at a position offset from the optical axis of the light emitting element or the light receiving element, a wedge prism that deflects the direction of light travel, and a lens / wedge prism rotation means that rotates the convex lens around a rotation axis offset from the lens center and rotates the wedge prism at a rotation speed different from the rotation speed of the convex lens. [Effects of the Invention]

[0015] In the present invention, by providing an optical axis adjustment means having a plurality of lenses including a convex lens whose lens center is positioned at a position offset from the optical axis of the light-emitting element or the light-receiving element, and lens rotation means for rotating at least two lenses including the convex lens at different rotation speeds around rotation axes offset from the respective lens centers, it is possible to perform high-precision optical axis adjustment. Furthermore, since the optical axis can be adjusted remotely, there is no need to remove the cover covering the optical axis adjustment means at the installation site, which is also suitable for making the photoelectric separated sensor waterproof. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view (part 1) of a light transmitter of a photoelectric separated sensor according to an embodiment of the present invention. [Figure 2] FIG. 2 is a view taken along the arrow AA in FIG. [Figure 3] FIG. 2 is a cross-sectional view (part 2) of the light transmitter of the separated photoelectric sensor according to the embodiment of the present invention. [Figure 4] FIG. 4 is a view taken along the arrow BB in FIG. 3. [Figure 5] This is an explanatory diagram (part 1) of the optical axis deflected according to the offset direction of two convex lenses. [Figure 6]This is an explanatory diagram (part 2) of the optical axis deflected according to the offset direction of two convex lenses. [Figure 7] This is an explanatory diagram (part 3) of the optical axis deflected according to the offset direction of two convex lenses. [Figure 8] 2A and 2B are diagrams for explaining a change in the deflection direction of the optical axis in accordance with the operation of the optical axis adjusting means of the light transmitter in FIG. 1 (part 1). [Figure 9] 1. FIG. 6 is a diagram (part 2) illustrating a change in the deflection direction of the optical axis in accordance with the operation of the optical axis adjusting means of the light transmitter in FIG. [Figure 10] 1. FIG. 4 is a diagram (part 3) illustrating a change in the deflection direction of the optical axis in accordance with the operation of the optical axis adjusting means of the light transmitter in FIG. [Figure 11] 1. FIG. 4 is a diagram for explaining a change in the deflection direction of the optical axis in accordance with the operation of the optical axis adjusting means of the light transmitter in FIG. [Figure 12] 1. FIG. 5 is a diagram for explaining a change in the deflection direction of the optical axis in accordance with the operation of the optical axis adjusting means of the light transmitter in FIG. [Figure 13] This is a diagram showing the light irradiation range corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The photoelectric separated sensor according to one embodiment of the present invention comprises a light transmitter having a light emitting element and a light receiver having a light receiving element, which are arranged opposite each other in a monitored space. The overall configuration of the photoelectric separated sensor is the same as that of a conventional sensor (see FIG. 2(a) of Patent Document 1), and therefore is not shown in the drawings. In the present invention, at least one of the light transmitter and the light receiver is provided with an optical axis adjustment means, which will be described later, but since the light transmitter and the light receiver have almost the same configuration except for the light emitting element, the light receiving element and their related circuits, this embodiment will be described taking as an example a case where the optical axis adjustment means is provided on the light transmitter side. The configuration of the main part of the light transmitter is shown in Figures 1 and 2.

[0018] As shown in Figures 1 and 2, the light transmitter 1 includes a light-emitting element 3 such as an LED, a light-emitting element accommodating section 5 which is a bottomed frame body that accommodates the light-emitting element 3, and an optical axis adjustment means 7 that adjusts the optical axis L of the light emitted by the light-emitting element 3. The optical axis adjusting means 7, which is a feature of the present invention, will be described in detail below.

[0019] <Optical axis adjustment means> As shown in Figures 1 and 2, the optical axis adjustment means 7 includes two convex lenses 9a and 9b arranged at positions where the lens centers 9a' and 9b' are offset from the optical axis of the light-emitting element 3, and a lens rotation means 11 that rotates the two convex lenses 9a and 9b at different rotation speeds around rotation axes offset from the respective lens centers 9a' and 9b'. As shown in FIGS. 1 and 2, of the two convex lenses, the convex lens arranged on the opposing device (light receiver) side is called convex lens 9a, and the convex lens arranged on the light emitting device side is called convex lens 9b.

[0020] The lens rotation means 11 is arranged in front of the light-emitting element 3 so that the center of rotation coincides with the optical axis of the light-emitting element 3, and is composed of large gears 13a and 13b that hold the convex lenses 9a and 9b, small gears 15a and 15b that mesh with the large gears 13a and 13b, and a motor 17 that rotates the small gears 15a and 15b.

[0021] When motor 17, which is the drive source of lens rotation means 11, is driven, pinion gears 15a and 15b connected to motor 17 rotate together. Furthermore, in conjunction with the rotation of pinion gears 15a and 15b, large gear 13a meshing with pinion gear 15a and large gear 13b meshing with pinion gear 15b each rotate.

[0022] The gear wheels 13a and 13b are formed with circular openings at positions offset from the center, and convex lenses 9a and 9b are fitted into the openings. 1 and 2, convex lens 9a is held by gear 13a with its lens center 9a' offset from the rotation axis O of gear 13a. Similarly, convex lens 9b is held by gear 13b with its lens center 9b' offset from the rotation axis O of gear 13b.

[0023] In this example, the amount of deviation between the rotation axis O and the lens center 9a' of the convex lens 9a (the offset amount of the convex lens 9a) is the same as the amount of deviation between the rotation axis O and the lens center 9b' of the convex lens 9b (the offset amount of the convex lens 9b). Note that the offset amounts of the convex lenses 9a and 9b do not necessarily have to be the same and may be different.

[0024] When the large gears 13a and 13b rotate, the convex lenses 9a and 9b held by the large gears 13a and 13b rotate around the rotation axis O. That is, when the motor 17 is driven, the small gears 15a and 15b rotate, and the large gears 13a and 13b rotate in conjunction with the small gears 15a and 15b, and the convex lenses 9a and 9b held by the large gears 13a and 13b rotate around the rotation axis O.

[0025] When the convex lens 9a rotates around the rotation axis O, the offset direction of the convex lens 9a, that is, the direction in which the lens center 9a' is displaced from the rotation axis O, changes. Similarly, when the convex lens 9b rotates around the rotation axis O, the offset direction of the convex lens 9b, that is, the direction in which the lens center 9b' is shifted from the rotation axis O, changes.

[0026] As described above, the lens rotating means 11 of this embodiment is configured to rotate the convex lenses 9a and 9b at different rotational speeds. This point will be explained below. In this embodiment, for example, as shown in FIG. 2, the number of teeth of the large gear 13a is 24, the number of teeth of the small gear 15a is 12, the number of teeth of the large gear 13b is 26, and the number of teeth of the small gear 15b is 10. When the rotation shaft of the motor 17 rotates once, the pinion 15a connected to the motor 17 also rotates once (360°), so the large gear 13a rotates by the number of teeth of the pinion 15a. Therefore, for every rotation of the motor 17, the large gear 13a rotates approximately 180° (12 / 24 = 1 / 2 rotation).

[0027] On the other hand, when the rotation shaft of the motor 17 rotates once, the pinion 15b also rotates once (360°), and so the large gear 13b also rotates by the number of teeth of the pinion 15b. Therefore, for each rotation of the motor 17, the large gear 13b rotates approximately 138° (10 / 26 = 5 / 13 rotation).

[0028] As described above, the lens rotation means 11 can rotate the two convex lenses 9a and 9b at different rotation speeds around the rotation axis O that is offset from the respective lens centers 9a' and 9b'. By rotating the convex lenses 9a and 9b at different rotation speeds, the positional relationship between the convex lenses 9a and 9b and their respective offset directions change from moment to moment.

[0029] Although the lens rotation means 11 described above is configured to rotate the two convex lenses 9a and 9b at different rotational speeds using one drive source (motor 17), the lens rotation means of the present invention is not limited to this. For example, a motor for rotating pinion 15a and a motor for rotating pinion 15b may be separately provided, so that the rotational speeds of pinion 15a and 15b are made different.

[0030] 2, the gear 13a is provided with a reference position marker 19 that indicates the reference position of the gear 13a. The reference position marker 19 of the gear 13a is provided on an extension of a line connecting the rotation axis O of the gear 13a and the lens center 9a' of the convex lens 9a, i.e., in the offset direction of the convex lens 9a. Similarly, the gear 13b is provided with a reference position marker 19 (not shown) that indicates the reference position of the gear 13b, in the offset direction of the convex lens 9b.

[0031] In this embodiment, the state in which the reference position marker 19 of the gear wheel 13a and the reference position marker 19 of the gear wheel 13b are aligned at a predetermined position is defined as the initial state before the motor is driven. Then, the period from the initial state when the motor 17 starts to be driven until the two reference position markers 19 are aligned at the same positions again is defined as one cycle.

[0032] The point that the optical axis adjusting means 7 changes (deflects) the traveling direction of the light emitted from the light emitting element 3 will be specifically described below. As shown in FIG. 1, light emitted from the light emitting element 3 (only the axis of the light (optical axis L) is shown in the figure) is incident on the convex lens 9b. As described above, the convex lens 9b is held at a position where the lens center 9b' is shifted (offset) from the rotation axis O. The rotation axis O coincides with the optical axis of the light-emitting element 3, so the lens center 9b' of the convex lens 9b is always shifted from the optical axis of the light-emitting element 3. Therefore, the light emitted by the light-emitting element 3 enters the convex lens 9b with its optical axis shifted from the lens center 9b' of the convex lens 9b, is deflected in the offset direction of the convex lens 9b, and exits from the convex lens 9b.

[0033] The light deflected by the convex lens 9b is incident on the convex lens 9a. The convex lens 9a is also held (offset) such that the lens center 9a' is shifted from the optical axis of the light-emitting element 3, so that the light incident on the convex lens 9a is further deflected in the offset direction of the convex lens 9a and exits from the convex lens 9a. In this way, the light emitted from the light emitting element 3 is deflected in two stages by the two convex lenses 9a and 9b and then emitted from the light transmitter 1.

[0034] 1 and 2 show a state in which the offset directions of convex lenses 9a and 9b are both aligned in the 6 o'clock direction. In this case, the light emitted by light-emitting element 3 is deflected in the offset direction (6 o'clock direction) of convex lenses 9a and 9b as shown in FIG. 1 and is emitted from the light transmitter.

[0035] In contrast, when the offset directions of convex lens 9a and convex lens 9b are opposite to each other, as shown in Figures 3 and 4, for example, the light deflected by convex lens 9b is deflected in the opposite direction by convex lens 9a. Therefore, when the offset amounts of the two convex lenses 9a and 9b are the same but the offset directions are opposite to each other, as in the examples of Figures 3 and 4, the light emitted by light-emitting element 3 is emitted from light transmitter 1 with almost no deflection.

[0036] The relationship between the offset direction of the convex lenses 9a and 9b and the deflection direction of light will be described more specifically with reference to FIGS. Figure 5(a) is a diagram showing the convex lenses 9a and 9b as seen from the opposing unit side, with the convex lens 9a shown in a solid line and the convex lens 9b behind the convex lens 9a shown in a dashed line. Figure 5(b) is a side view of Figure 5(a).

[0037] Figure 5 shows a state in which the offset directions of the two convex lenses 9a, 9b are both aligned in the 12 o'clock direction. As explained in Figures 1 and 2, when the offset directions of the two convex lenses 9a, 9b are aligned in the same direction, light 21 emitted by the light-emitting element 3 is deflected in the offset direction of the two convex lenses 9a, 9b (in this case, the 12 o'clock direction) and is emitted from the convex lens 9a.

[0038] Next, Fig. 6 shows the state when the offset directions of the two convex lenses 9a and 9b are opposite to each other. Fig. 6(a) is a schematic diagram of the convex lenses 9a and 9b as seen from the opposing unit side, similar to Fig. 5(a), and Fig. 6(b) is a side view of Fig. 6(a). In FIG. 6, the offset direction of convex lens 9a is the 6 o'clock direction, and the offset direction of convex lens 9b is the 12 o'clock direction, so that the offset directions of the two convex lenses 9a and 9b are opposite to each other. At this time, the light 21 emitted by the light emitting element 3 is emitted from the convex lens 9a with almost no deflection, similar to the cases of FIGS.

[0039] An example in which the offset directions of the two convex lenses 9a, 9b are neither the same nor opposite is shown in Figure 7. Figure 7(a) is a schematic diagram of the convex lenses 9a, 9b as seen from the opposing unit side, similar to Figures 5(a) and 6(a), and Figure 7(b) is a side view of Figure 7(a). Also, Figure 7(c) is a schematic diagram of Figure 7(a) as seen from below. In FIG. 7, the offset direction of the convex lens 9a is the 3 o'clock direction when viewed from the opposing device side, and the offset direction of the convex lens 9b is the 12 o'clock direction. At this time, the light 21 emitted by the light emitting element 3 is deflected in the offset direction of the convex lens 9a and the offset direction of the convex lens 9b as shown in FIGS. 7(b) and 7(c), and is emitted from the convex lens 9a.

[0040] As described above, the light 21 emitted from the light-emitting element 3 is deflected in two stages by passing through the two convex lenses 9a and 9b offset from the optical axis of the light-emitting element 3, and is then emitted from the light transmitter 1. The deflection directions correspond to the offset directions of the convex lenses 9a and 9b.

[0041] As described above, the two convex lenses 9a, 9b are rotated around the optical axis at different rotation speeds by the lens rotation means 11, and therefore the offset directions of the two convex lenses 9a, 9b change at different speeds from moment to moment. As the offset directions of the convex lenses 9a, 9b change, the deflection direction of the light emitted from the light transmitter 1 also changes in various ways. This point will be explained in detail using FIGS. 8 to 12.

[0042] 8 to 12 show the deflection direction when light 21 emitted by light-emitting element 3 is deflected using optical axis adjustment means 7 described with reference to FIGS. 1 to 4, in terms of horizontal deflection angle x [°] and vertical deflection angle y [°] (see FIG. 7). When the horizontal deflection angle x is + (plus), it indicates that optical axis L is deflected to the right in the horizontal direction, and when it is - (minus), it indicates that optical axis L is deflected to the left in the horizontal direction. Furthermore, when the vertical deflection angle y is + (plus), it indicates that optical axis L is deflected vertically upward, and when it is - (minus), it indicates that optical axis L is deflected vertically downward.

[0043] 8 shows the locus of change in the deflection direction of the optical axis L from the initial state before driving the motor 17 until the motor 17 makes one rotation. In this embodiment, the initial state is a state in which the reference position marker 19 of the gear wheel 13a and the reference position marker 19 of the gear wheel 13b are aligned in the 12 o'clock direction. In the initial state before the motor is driven, the offset directions of the convex lenses 9a and 9b are both aligned at 12 o'clock, so the light emitted from the light transmitter 1 is deflected vertically upward, as shown by the "START" point in Figure 8. When motor 17 is driven, convex lenses 9a and 9b rotate around the optical axis (rotation axis O of large gears 13a and 13b) of light-emitting element 3 at different rotational speeds as large gears 13a and 13b rotate, changing the offset direction of convex lenses 9a and 9b. As the offset direction of convex lenses 9a and 9b changes, the deflection direction of optical axis L also changes as shown in FIG.

[0044] Thereafter, the offset direction of convex lenses 9a and 9b continues to change from moment to moment, and the deflection direction of optical axis L changes as shown in Figures 9 to 11. In the figures, gear wheel 13a is referred to as "gear A" and gear wheel 13b is referred to as "gear B."

[0045] FIG. 12 shows the locus of change in the deflection direction of the optical axis L until the convex lenses 9a and 9b are aligned in the initial state position, that is, when the convex lenses 9a and 9b continue to rotate for one cycle. As shown in FIG. 12, the direction of deflection of light changes in various ways while the convex lenses 9a and 9b are rotated for one cycle.

[0046] Note that Figure 12 shows the change in the deflection direction (horizontal deflection angle x and vertical deflection angle y) of the optical axis L of the light 21 emitted from the light transmitter 1, and Figure 13 shows the corresponding irradiation range of the light 21. Figure 13 shows, with 156 sampled points on the trajectory in Figure 12, the illumination range of light 21 at each point when the illumination angle is 1.4°, as a circle. Looking at Figure 13, it can be seen that by rotating convex lenses 9a and 9b once, light 21 is irradiated without omission within a range of ±4° horizontally and ±4° vertically from the optical axis of light-emitting element 3. Therefore, if the optical axis of the light-receiving element of the optical receiver, which is the opposing device, is positioned within the above ranges, light 21 from light-emitting element 3 can be made to reach the light-receiving element.

[0047] <Optical axis adjustment method> An example of a method for adjusting the optical axis of the photoelectric separated type sensor configured as above will be described. The optical axis adjustment is performed after the light transmitter 1 and the light receiver are placed opposite each other in the monitored space. At that time, the light receiver is placed within the adjustment range of the optical axis adjustment means 7 of the light transmitter 1. In this example, the adjustable range of the optical axis adjustment means 7 is ±4° horizontally and ±4° vertically from the optical axis of the light emitting element 3, so the light transmitter 1 and the light receiver are placed so that the light receiving element is placed within this range.

[0048] The optical axis adjustment is performed by rotating the two convex lenses 9a and 9b of the optical axis adjustment means 7 provided in the light transmitter 1 and identifying the optimal positions of the two convex lenses 9a and 9b based on the amount of light received by the light receiver.

[0049] Below, we will explain a method of scanning the adjustment range of the optical axis adjustment means 7 to obtain received light amount information (scanning process), identifying the optimal positions of the two convex lenses 9a and 9b based on the received light amount information (adjustment position identification process), and arranging the two convex lenses 9a and 9b at the identified positions to adjust the optical axis (adjustment process).

[0050] The method described below can be performed remotely using a control means (not shown). The control means includes, for example, a motor control means for controlling the motor 17 of the lens rotation means 11, a reference position marker detection means for detecting the reference position markers of the large gears 13a and 13b, a received light amount detection means for detecting the amount of light received by the light receiver, and a received light amount storage means for storing the detected received light amount in correspondence with the driving time of the motor 17 at the time of detection.

[0051] <Scanning process> In the scanning process, the convex lenses 9a and 9b of the light transmitter 1 are rotated one cycle, and the amount of light received during that period and the corresponding driving time of the motor 17 are acquired and stored. In the initial state before rotation, the reference position markers 19 of the large gears 13a and 13b are aligned at predetermined positions. These positions are monitored by the reference position marker detection means, which is capable of detecting the presence or absence of the two reference position markers 19 at these positions.

[0052] When the motor 17 is driven, the large gears 13a and 13b rotate, and the convex lenses 9a and 9b rotate at different speeds. As described above, the offset directions of convex lenses 9a, 9b change as convex lenses 9a, 9b rotate, and therefore the deflection direction of light emitted from light transmitter 1 changes from moment to moment, as explained in Figures 8 to 12. As the deflection direction of light changes, the amount of light that reaches the light receiving element of the light receiver (amount of received light) also changes, so the changing amount of received light is constantly detected and recorded together with the driving time of motor 17 at the time of detection. When rotation continues for a certain period of time, the two reference position markers 19 are aligned again at the predetermined positions of the initial state, and when this is detected by the reference position marker detection means, the motor 17 is stopped.

[0053] ≪Adjustment position identification process≫ In the adjustment position specifying step, the optimum positions of the two convex lenses 9a and 9b are specified based on the information on the amount of received light recorded in the scanning step. For example, the positions of the two convex lenses 9a and 9b when the amount of received light is greatest in one cycle can be determined as the optimal positions. That is, if the amount of received light is greatest α seconds after the motor 17 starts to drive, the positions of the convex lenses 9a and 9b α seconds after the motor 17 starts to drive will be the optimal positions of the convex lenses 9a and 9b.

[0054] ≪Adjustment process≫ In the adjustment step, the convex lenses 9a and 9b are placed in the optimal positions identified in the adjustment position identification step. If the positions of the convex lenses 9a and 9b after α seconds are identified as the optimal positions as described above, the motor 17 is driven for α seconds at the same speed as in the scanning step. Once the large gears 13a and 13b have rotated for α seconds and the two convex lenses 9a and 9b have been placed in the optimal positions, the optical axis adjustment is complete.

[0055] The above is an optical axis adjustment method when the optical axis adjustment means 7 is provided only on the light transmitter 1 side. However, if the optical axis adjustment means 7 is also provided on the light receiver side, it is advisable to perform the optical axis adjustment on the light receiver side after completing the optical axis adjustment of the light transmitter 1. By performing a similar optical axis adjustment on the light receiver side, the amount of received light can be further increased, and more accurate optical axis adjustment can be performed.

[0056] The optical axis adjustment means may be provided only on the light receiver side. In this case, when the light transmitter and light receiver are arranged opposite each other, the position is adjusted so that light from the light transmitter is incident on the convex lens of the optical axis adjustment means of the light receiver, and then the optical axis is adjusted on the light receiver side. Note that if the light transmitter is configured to be able to emit diffused light, for example by using a lamp as the light-emitting element, this makes it easier for the light to be incident on the convex lens of the light receiver, which is preferable as it reduces the work of adjusting the positions of the light transmitter and light receiver.

[0057] As described above, in this embodiment, the optical axis can be adjusted so that the amount of received light is maximized within the adjustment range of the optical axis adjustment means 7. When adjusting the optical axis manually as in the conventional case, it was difficult to adjust the optical axis so that the amount of received light is maximized within the adjustment range, but by using the photoelectric separated sensor of this embodiment, it is possible to adjust the optical axis with higher precision than before.

[0058] In addition, since the optical axis can be adjusted remotely using a control means (not shown), there is no need to remove the main body cover at the installation site during adjustment work. Therefore, it is also suitable for making the photoelectric separated type detector waterproof.

[0059] The optical axis adjustment method in the above-described embodiment is an example in which the optical axis can be adjusted so that the amount of received light is maximized within the adjustment range, but the optical axis adjustment method in the present invention is not limited to this. For example, a target amount of received light may be determined in advance, and if an amount of received light exceeding the target amount of received light is detected during scanning in the scanning process, the rotation of the two convex lenses may be stopped at that point, and the optical axis adjustment may be terminated.

[0060] Furthermore, although the optical axis adjustment means in the photoelectric separated sensor of this embodiment uses two lenses that are both convex lenses, the present invention is not limited to this, and either one of the convex lenses 9a, 9b may be a concave lens or other lens. Furthermore, the number of lenses is not limited to two, and may be three or more. In any case, at least one of the multiple lenses includes a convex lens and is configured to be able to focus light.

[0061] The lens rotation means of the present invention may be configured to rotate at least two of the plurality of lenses, including a convex lens, at different rotation speeds around rotation axes offset from the centers of the respective lenses. In other words, it is sufficient that the convex lens and at least one other lens (which may be another convex lens, a concave lens, etc.) rotate at different rotational speeds, so when there are three or more lenses, it is not necessary for all of the lenses to rotate at different speeds. Therefore, the present invention also includes an embodiment in which a third lens is fitted together with convex lens 9a in the opening of gear wheel 13a in which convex lens 9a in the example of Figure 1 is fitted.

[0062] Furthermore, instead of the other lenses, a wedge prism may be provided. Since a wedge prism can deflect the traveling direction of light like a lens, for example, using one convex lens and one wedge prism can deflect light in two stages. Furthermore, multiple wedge prisms may be used, or a wedge prism may be combined with a concave lens, etc.

[0063] In the case of a lens, the lens center must be offset from the optical axis in order to deflect light, but in the case of a wedge prism, even light that enters the center of the shape will be deflected, so as long as the position is such that light enters, the position relative to the optical axis does not matter. Therefore, when deflecting light using a convex lens and a wedge prism, it is preferable to provide, instead of the lens rotation means described above, a lens / wedge prism rotation means that rotates the convex lens around a rotation axis offset from the lens center and rotates the wedge prism at a rotation speed different from that of the convex lens. [Explanation of symbols]

[0064] 1 Light transmitter 3 Light-emitting element 5 Light emitting element housing section 7 Optical axis adjustment means 9a Convex lens 9a´ Lens center 9b Convex lens 9b´ Lens center 11 Lens rotation means 13a Gear 13b Gear 15a Pinion 15b Pinion 17 Motor 19 Reference Position Marker 21 light

Claims

1. A photoelectric separation type sensor comprising a light transmitter having a light emitting element and a light receiver having a light receiving element, disposed opposite each other in a monitored space, At least one of the light transmitter and the light receiver is provided with an optical axis adjustment means, the optical axis adjusting means includes a plurality of lenses including a convex lens whose center is positioned so as to be offset from the optical axis of the light emitting element or the light receiving element; and lens rotation means for rotating at least two lenses including the convex lens at different rotation speeds around rotation axes offset from the centers of the respective lenses.

2. The lens rotation means 2. The photoelectric separated sensor according to claim 1, wherein the plurality of lenses are rotated around the optical axis as a rotation axis.

3. 3. A method for adjusting an optical axis of a photoelectric separated sensor according to claim 1 or 2, comprising: A method for adjusting the optical axis of a photoelectric separated sensor, comprising rotating the plurality of lenses and identifying the optimum positions of the plurality of lenses based on the amount of light received by the light receiver.

4. 4. The method for adjusting the optical axis of a photoelectric separated sensor according to claim 3, wherein the positions of the plurality of lenses before rotation are set as initial positions, the rotation is continued until the lenses return to the initial positions, and then the positions of the plurality of lenses when the amount of received light is greatest are identified as optimal positions of the plurality of lenses, and the plurality of lenses are positioned at the optimal positions.

5. A method for adjusting the optical axis of a photoelectric separation type sensor in which a light transmitter having a light emitting element and a light receiver having a light receiving element are arranged opposite each other in a monitored space, comprising: A method for adjusting the optical axis of a photoelectric separated sensor, characterized in that at least two lenses, including a convex lens provided in the light transmitter and / or the light receiver, whose lens center is positioned at a position offset from the optical axis of the light emitting element or the light receiving element, are rotated around rotation axes offset from the respective lens centers at different rotation speeds, and the optimal position of the lenses is identified based on the amount of light received by the light receiver.

6. 6. The method for adjusting the optical axis of a photoelectric separated sensor according to claim 5, wherein the positions of at least two lenses including the convex lens before rotation are set as initial positions, the rotation is continued until the lenses return to the initial positions, and then the position of the lenses when the amount of received light is greatest is identified as an optimal position of the lenses, and the lenses are positioned at the optimal position.

7. A photoelectric separation type sensor comprising a light transmitter having a light emitting element and a light receiver having a light receiving element, disposed opposite each other in a monitored space, At least one of the light transmitter and the light receiver is provided with an optical axis adjustment means, The optical axis adjusting means includes a convex lens whose center is shifted from the optical axis of the light emitting element or the light receiving element, and a wedge prism that deflects the traveling direction of light. a lens / wedge prism rotating means for rotating the convex lens around a rotation axis offset from the center of the lens and for rotating the wedge prism at a rotation speed different from that of the convex lens.

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