JP4613153B2 - Reflective sensor for automatic door opening / closing control - Google Patents

Description

  The present invention relates to a reflection type sensor for automatic door opening / closing control using infrared rays, and more specifically, automatic door opening / closing control for preventing malfunction of an automatic door caused by strong reflected light reflected from a light reflecting material such as metal or glass. The present invention relates to a reflection type sensor.

  In a reflective sensor for automatic door opening / closing control using infrared rays (hereinafter, simply referred to as “reflective sensor”), an infrared light emitting element and an infrared light receiving element are arranged in parallel above the automatic door, and the automatic door Use the nearby floor as a monitoring area, irradiate infrared light from the infrared light emitting element toward the monitoring area, receive the reflected light from the monitoring area with the infrared light receiving element, and approach the automatic door by changing the amount of light received It detects an object such as a person who performs, and gives an open signal to the automatic door.

  Usually, an infrared light emitting diode is used for the infrared light emitting element, and a photodiode is used for the infrared light receiving element. Further, in many cases, an invisible portion of the automatic door is selected as the mounting position, and sensitivity adjustment is performed so as to obtain an optimum sensitivity in consideration of reflection from a floor surface or a surrounding wall surface at the time of installation.

  In addition, with respect to the effects of changes in reflectance due to, for example, floor waxing or floor contamination after installation, an automatic tracking type sensitivity adjustment function is provided for the total amount of reflected light, and a certain range. In this case, the overall sensitivity (threshold value) is changed (see Patent Document 1 as an example).

JP 2003-3750 A

  However, after installation, due to interior refurbishment, for example, a metal fence is struck on the floor surface of the monitoring area, or a strong reflective material such as a glass ornament is installed near the automatic door, and the strong reflective material is made from an infrared light emitting element. If the reflected infrared light hits and the reflected light is generated, the automatic tracking type sensitivity adjustment function cannot cope with it, and the automatic door may suddenly open.

  In addition, since the multiple reflections by the strong reflectors often have a sharp directivity, even if the ray trace of the reflected light does not return to the infrared light receiving element at first, the building may be distorted due to a load change or the like. Then, the reflected light may suddenly enter the infrared light receiving element.

  The elucidation of the cause of the malfunction that occurs after such installation must be dealt with in the field from time to time, but because it is invisible because it is infrared, ray tracing of the reflected light by the strong reflector is not easy, It will take a lot of time to elucidate the cause.

  On the other hand, assuming the presence of reflected light by the above strong reflectors, if the sensitivity of the entire control system is reduced in advance, the automatic door may not open even if a person who should be detected originally approaches due to insufficient sensitivity, The sensitivity adjustment requires many trials and errors, and is also uneconomical in time.

  Therefore, an object of the present invention is to provide a reflective sensor for automatic door opening / closing control that does not pick up light reflected by a strong reflective material such as metal or glass existing on a floor surface or wall surface in the vicinity of the automatic door. It is in.

  Infrared rays include, as linearly polarized light, an S-polarized component perpendicular to the incident surface (Senchrecht in German) and a P-polarized component parallel to the incident surface. When the component is totally reflected by a strong reflecting material such as metal or glass, its polarization plane is maintained and the reflected light is S-polarized light. On the other hand, in the case of diffuse reflection, the S-polarized light is broken, and both the S-polarized component and the P-polarized component exist in the reflected light.

  The incident angle at which the light reflected at the interface of substances having different refractive indexes becomes completely polarized is called the Brewster angle (or polarization angle), and the reflected light of the P-polarized component is approximately Brewster's angle up to “0”. While it decreases and then increases, the S-polarized component has a characteristic of increasing monotonously.

The present invention has been made in view of this point, in order to solve the above problems, the automatic door near a surveillance area is located at a predetermined position with respect to the automatic door toward said monitoring area Infrared In the reflective sensor for automatic door opening / closing control, comprising: an infrared light emitting element that emits light; and an infrared light receiving element that is disposed at a predetermined position with respect to the automatic door and that receives reflected light from the monitoring area. A first polarized light reflecting means having a Brewster angle that is disposed in a light forward path from the light emitting element to the monitoring region and has an interface reflection of only the S-polarized component contained in the infrared light emitted from the infrared light emitting element, and from the monitoring region disposed backward light reaching to the infrared receiving component, only the P-polarized light component included in the reflected light and a second polarized light reflecting means for interfacial reflection, the first polarized light reflected hands As the second polarized light reflecting means, first and second concave mirrors made of an optical member such as a glass material and having a curved surface near the Brewster angle reflecting the S polarized light component at the interface are used. The direction of the second concave mirror is shifted by 90 ° with respect to the first concave mirror as the first polarized light reflecting means .

According to the onset bright, a first polarizing reflector means having a Brewster angle that only the interfacial reflected S-polarized component contained in the infrared radiation emitted from the infrared light-emitting element to the light outgoing path leading to the monitoring area from the infrared light emitting element with placing, by only P-polarized light component contained in reflected light to return the light reaching from the monitoring region to an infrared light receiving element by arranging the second polarized reflection means for interfacial reflection, such as a human which is present in the monitored area Reliability of automatic doors because only diffusely reflected light is received by the infrared light receiving element, and light reflected by strong reflective materials such as metal and glass existing on the floor or wall near the automatic door is not picked up. Can be further enhanced.

Further, as the first polarized light reflecting means and the second polarized light reflecting means, there are used first and second concave mirrors made of an optical member such as a glass material and having a curved surface near the Brewster angle that reflects the S polarized light component at the interface. Since the direction of the second concave mirror as the two-polarized reflecting means is shifted by 90 ° with respect to the first concave mirror as the first polarized-reflecting means, the first concave mirror and the second concave mirror may be substantially the same. At the same time, the lens system is not required due to the condensing action of the concave mirror, and the cost can be reduced accordingly.

Next, the first to fourth embodiments will be described with reference to FIGS. 1 to 6. The first, second, and fourth embodiments are reference embodiments, and the third embodiment relates to claim 1. It is an embodiment.

First, a first embodiment (reference embodiment) of the present invention shown in FIG. 1 will be described. The reflection type sensor according to the first embodiment includes an infrared light emitting element 10 such as an infrared light emitting diode and an infrared light receiving element 20 including a photodiode as a basic configuration. Although only one infrared light emitting element 10 and one infrared light receiving element 20 are shown as a pair in the figure, a plurality of pairs are actually used.

  The infrared light emitting element 10 and the infrared light receiving element 20 are arranged side by side in an unshown automatic door, for example, and the infrared light emitting element 10 has a floor surface in the vicinity of the automatic door as a monitoring area F, and faces the monitoring area F. Infrared rays are emitted. In the first embodiment and each embodiment described later, it is assumed that a person H that is an object to be detected and a metal rod R that is a strong reflector exist in the monitoring area F. Yes.

Note that placing an infrared light-emitting element 10 and the infrared light receiving element 20 for example on the side or diagonally above the automatic door, but it may also be impregnated with the wall near the automatic door not only floor in the surveillance area.

  The infrared light receiving element 20 receives the reflected light from the monitoring region F, and supplies the received light signal to the determination logic circuit 32 included in the control system via the amplifier 31. The determination logic circuit 32 is provided with, for example, a window comparator, and outputs an open signal to the door engine of the automatic door when the amount (or intensity) of reflected light exceeds a predetermined threshold value. The determination logic circuit 32 may be a commonly used one.

  In the present invention, the infrared light receiving element 20 receives only polarized light in one direction out of the amount of light emitted from the infrared light emitting element 10 as will be described later. Therefore, since the amount of received light decreases, it is necessary to increase the amplification degree of the amplifier 31, for example.

  In the first embodiment, the first polarizing filter 11 and the light projecting lens 12 are arranged on the light forward path A from the infrared light emitting element 10 to the monitoring area F, and on the light return path B from the monitoring area F to the infrared light receiving element 20. A second polarizing filter 21 and a condenser lens 22 are disposed.

  The first polarizing filter 11 on the light emitting side is a polarizing filter that passes only the S-polarized component contained in the infrared light emitted from the infrared light emitting element 10, and the second polarizing filter 21 on the light receiving side is from the monitoring region F. This is a polarizing filter that allows only the P-polarized component contained in the reflected light to pass through. As the first polarizing filter 11 and the second polarizing filter 21, various types such as a diffraction grating type and a polarizing film can be used.

  According to this, the infrared light (S-polarized light) having only the S-polarized component is emitted from the infrared light emitting element 10 to the monitoring region F. Of this S-polarized light, the reflected light totally reflected by the metal rod R is still S-polarized light while maintaining its polarization plane, and is therefore blocked by the second polarizing filter 21 on the light receiving side. Not incident on the light receiving element 20

  On the other hand, since the reflection by the person H is diffuse reflection, the polarization of the S-polarized light is lost, and the reflected light includes an S-polarized component and a P-polarized component. Therefore, only the infrared light (P-polarized light) of the P-polarized component passes through the second polarizing filter 21 on the light receiving side and enters the infrared light receiving element 20. The determination logic circuit 32 outputs a “door open” or “door close” signal to the door engine based on the fluctuation amount (or intensity) of the P-polarized light.

  In the embodiment described here, for convenience of explanation, the light emitting side is S-polarized light and the light receiving side is P-polarized light, but these may be orthogonally polarized light.

  In this way, the highly directional reflected light that is totally reflected from a strong reflecting material such as metal or glass is removed. The first polarizing filter 11 is described in, for example, Japanese Patent Application Laid-Open No. 2004-145305. By using such a PS polarization conversion element, it is possible in principle to prevent the light intensity of the first polarizing filter 11 from being halved, and thereby the output power of the infrared light emitting element 10 can be relatively reduced. Can be lowered.

  Moreover, the infrared laser light source 110 shown in FIG. This infrared laser light source 110 is a laser light source capable of emitting arbitrarily polarized light, and a half mirror 112 for irradiating a laser beam toward an irradiated body is disposed on one emission surface 111a side of the laser generator 111, and the other. A light reflecting plate 113 for amplifying laser light is disposed on the emission surface 111b side.

  According to the infrared laser light source 110, for example, an S-polarized infrared laser can be obtained by selecting the Brewster angle θa on the other emission surface 111b side and oscillating in the polarization mode. Therefore, by using the infrared laser light source 110, the first polarizing filter 11 on the light emission side can be omitted.

  The light emitting side light projecting lens 12 and the light receiving side condensing lens 22 may be arranged either before or after the polarizing filters 11 and 21, but a plurality of infrared light emitting elements 10 and infrared light receiving elements 20 are used. In order to reduce the number (cost) of the polarizing filter used, it is preferable that the polarizing filter is disposed on the infrared light emitting element 10 side and the infrared light receiving element 20 side.

Next, a second embodiment (reference embodiment) of the present invention shown in FIG. 3 will be described. In the second embodiment, instead of the first and second polarizing filters 11 and 12 in the first embodiment, the first polarizing reflector 13 is disposed in the light forward path A from the infrared light emitting element 10 to the monitoring region F. The second polarizing reflector 23 is disposed in the optical return path B from the monitoring region F to the infrared light receiving element 20.

  The first polarizing reflector 13 and the second polarizing reflector 23 are both made of a flat reflector such as flat glass, and the first polarizing reflector 13 on the light emission side has an incident angle of infrared light emitted from the infrared light emitting element 10. The Brewster angle θb that reflects only the S-polarized component at the interface is arranged.

  On the other hand, the second polarization reflector 23 on the light receiving side reflects only the P-polarized component included in the reflected light from the monitoring region F at the interface. In order to realize this, since the polarization planes of the S polarization component and the P polarization component are shifted by 90 °, the incident angle of the reflected light with respect to the second polarization reflection plate 23 is the same Brewster angle θb as that of the first polarization reflection plate 13. Thus, the polarization plane of the second polarization reflector 23 may be shifted by 90 ° with respect to the polarization plane of the first polarization reflector 13.

  Also in the second embodiment, infrared light having only the S-polarized component (S-polarized light) is irradiated onto the monitoring region F by the first polarizing reflector 13 on the light emission side, and the S-polarized light totally reflected by the metal rod R is irradiated. Since the reflected light is blocked by the second polarizing reflection plate 23 on the light receiving side, it is not incident on the infrared light receiving element 20.

  On the other hand, the reflection by the person H is diffuse reflection, and the reflected light includes an S-polarized component and a P-polarized component, and only infrared light (P-polarized light) of the P-polarized component is included. The light is selected by the second polarizing reflector 23 on the light receiving side and is incident on the infrared light receiving element 20.

  In the second embodiment, the light projecting lens 12 and the condenser lens 22 are disposed on the infrared light emitting element 10 and the infrared light receiving 20 side, respectively. However, in some cases, as in the first embodiment. You may arrange | position on the counter element 10 and 20 side.

Next, a third embodiment ( embodiment according to claim 1) of the present invention will be described with reference to FIG. The third embodiment is cost effective particularly when the infrared light emitting element 10 and the infrared light receiving element 20 are used as a plurality of pairs (three pairs in this example). The first and second embodiments in the second embodiment are effective. Instead of the polarizing reflectors 13 and 14, the first and second concave mirrors 14 and 24 are used on the light emitting side and the light receiving side.

  According to this, when a plurality of light spots are formed in the monitoring area F, the lens system including the light projecting lens and the condensing lens, which has been conventionally required, is unnecessary due to the condensing function of the concave mirror, and the cost is reduced accordingly. Can be planned.

  Both the first and second concave mirrors 14 and 24 are preferably made of a transparent material having a high optical refractive index such as glass or PMMA acrylic resin or AS acrylic styrene resin, and have a curved surface near the Brewster angle θb that reflects the S-polarized light component at the interface. It is a concave mirror.

  In this case, since the first and second concave mirrors 14 and 24 are made of a transparent material, it is preferable to dispose black bodies 14a and 24a for absorbing transmitted light on the back surfaces thereof. The concave mirror is not necessarily made of a transparent material, and may be a black body or the like as long as the refractive index is high.

As described above, since the S-polarized light component and P-polarized light component phase is 90 DEG, in order to select only P-polarized light component in the second concave mirror 24 on the light receiving side, the polarization plane of the second concave mirror 24 on the light receiving side Is shifted by 90 ° with respect to the polarization plane of the first concave mirror 14 on the light emitting side. As shown in FIG. 4, if the polarization plane of the first concave mirror 14 on the light emitting side is facing the front, the polarization plane of the second concave mirror 24 on the light receiving side is set sideways.

  According to the third embodiment, only the S-polarized component included in the infrared rays emitted from the plurality of infrared light emitting elements 10 is selected by the first concave mirror 14 and irradiated to the monitoring region F. On the other hand, the reflected light from the monitoring region F is collected by the second concave mirror 24, and only the P-polarized component included in the reflected light is selected, and each infrared light receiving element 20 corresponding to each infrared light emitting element 10 is selected. Is incident on.

  The curved surfaces of the concave mirrors 14 and 24 may be variously selected depending on the application and accuracy, such as a paraboloid, an ellipsoid, a spherical surface, and an aspherical surface. In order to correspond to each of the infrared light receiving elements 20 with each one of the concave mirrors 14 and 24, it is important to place the elements 10 and 20 close to each other and bring them close to the focal point. Further, when the reflection of the S-polarized light component is small in one transparent plate, the transparent plates may be stacked in multiple layers or a multiple reflection film may be formed on the glass surface.

  When the monitoring area F is wide, as shown in FIG. 5, a plurality of (three in this example) reflective sensors according to the third embodiment may be used in parallel. In this case, in order to prevent stray light between adjacent infrared light receiving elements 20, it is preferable to arrange a light shielding cover 24a between them.

Next, a fourth embodiment (reference embodiment) of the present invention will be described with reference to FIG. In the fourth embodiment, attention is paid to the fact that the polarization direction of the reflected light totally reflected by a strong reflecting material such as metal or glass is reversed left and right. In FIG. 6, the amplifier circuit 31 connected to the infrared light receiving element 20 and the determination logic circuit 32 of the control system are omitted.

  According to the fourth embodiment, the infrared rays emitted from the infrared light emitting element 10 and the monitoring are sent to the optical forward path A from the infrared light emitting element 1 to the monitoring area F and the optical backward path B from the monitoring area F to the infrared light receiving element 20. Polarization filters 61 having the same characteristics that allow only one of the S-polarized component and the P-polarized component included in the reflected light from the region F to pass are disposed.

  A quarter-wave plate 62 is disposed on the light emitting side of the polarizing filter 61 on the light emitting side and on the light incident side of the polarizing filter 61 on the light receiving side. In this example, a lens 63 for projecting and collecting light is disposed between the quarter wavelength plate 62 and the monitoring region F. However, the lens 63 includes the polarizing filter 61 and the quarter wavelength plate 62. Or between the elements 10 and 20.

  For example, the polarizing filter 61 is a polarizing filter that allows only the S-polarized component (S-polarized light) to pass through. The S-polarized light is converted into, for example, left-handed circularly polarized light by the quarter-wave plate 62, and is input to the monitoring region F. When it is irradiated and totally reflected by the metal rod R exemplified as a strong reflection material, the polarization direction is reversed left and right, so that the reflected light becomes right-handed circularly polarized light.

  The reflected light is returned to linearly polarized light again by the quarter-wave plate 62, but its polarization plane is P-polarized light that is opposite to S-polarized light at the time of irradiation, so that the polarizing filter 61 blocks its passage. . Thereby, the reflected light from the strong reflecting material is not detected by the infrared light receiving element 20.

  On the other hand, the reflected light reflected by the person H or the like is diffusely reflected light and contains an S-polarized component and a P-polarized component. The light is returned to linearly polarized light, passes through the polarizing filter 61, and is detected by the infrared light receiving element 20.

  Thus, in the fourth embodiment, an object such as a person approaching the automatic door can be reliably detected without picking up the reflected light from the strong reflector, but in the case of the fourth embodiment, the irradiation light Is converted into circularly polarized light by the ¼ wavelength plate 62, and therefore, it is more effective for reflected light from an inclined metal surface or the like than linearly polarized light.

The schematic diagram which shows 1st Embodiment of this invention. The schematic diagram which shows the laser light source applicable to the said 1st Embodiment. The schematic diagram which shows 2nd Embodiment of this invention. The schematic diagram which shows 3rd Embodiment of this invention. The schematic diagram which shows the modification of the said 3rd Embodiment. The schematic diagram which shows 4th Embodiment of this invention.

DESCRIPTION OF SYMBOLS 10 Infrared light emitting element 11 1st polarizing filter 12 Projection lens 13 1st polarizing reflector 14 1st concave mirror 20 Infrared light receiving element 21 2nd polarizing filter 22 Condensing lens 23 2nd polarizing reflector 24 2nd concave mirror 32 Judgment logic circuit 61 Polarizing filter 62 1/4 wavelength plate

Claims (1)

An infrared light emitting element that is arranged at a predetermined position with respect to the automatic door and emits infrared rays toward the monitoring area, and a monitoring area that is arranged at a predetermined position with respect to the automatic door, with the vicinity of the automatic door as a monitoring area In a reflective sensor for automatic door opening and closing control including an infrared light receiving element that receives reflected light from
A first polarized light reflecting means disposed on an optical path from the infrared light emitting element to the monitoring region, and having a Brewster angle for interfacial reflection of only the S-polarized component contained in the infrared light emitted from the infrared light emitting element; A second polarized light reflecting means disposed on the optical return path from the monitoring region to the infrared light receiving element and configured to interface-reflect only the P-polarized light component contained in the reflected light ;
As the first polarized light reflecting means and the second polarized light reflecting means, there are used first and second concave mirrors made of an optical member such as a glass material and having a curved surface near the Brewster angle that reflects the S polarized light component at the interface. A reflection type sensor for automatic door opening / closing control, characterized in that the second concave mirror as the second polarized light reflecting means is shifted by 90 ° with respect to the first concave mirror as the first polarized light reflecting means .

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