JP4007965B2 - Object detection device - Google Patents

Description

  The present invention relates to an object detection device that detects the presence or absence of an object such as a person using an optical signal that emits light at a predetermined frequency.

There are two types of the object detection device, a transmission type and a reflection type. In the case of the transmission type, the presence / absence of light that is transmitted through the predetermined location of the object by the light signal having a predetermined emission frequency transmitted toward the predetermined location of the object In addition, in the case of the reflection type, the presence or absence of an object at the planned location is detected based on the presence or absence of light reflected by the object at the planned location where the optical signal transmitted to the planned location of the object is reflected. is there.
However, when an optical signal having a single emission frequency is used in the object detection device, an optical signal having an emission frequency that is the same as or approximate to the emission frequency of the optical signal is transmitted from another remote controller or the like and enters the object detection device. In addition, the legitimate optical signal may not be properly received due to interference of disturbance light signals from a remote controller or the like, and object detection may not be performed properly.

  Therefore, conventionally, in a reflection-type object detection device, two optical signals having different emission frequencies are alternately transmitted toward a place where the object is to be present, and light reflected at the place where the light signal having one frequency is reflected. When the light is received, an optical signal of the other frequency is transmitted at a short time interval, and when the light reflected by the other optical signal is received at the existing location, the presence of the object at the existing location is detected. (See Patent Document 1).

JP-A-8-128087

  In the object detection device described in Patent Document 1, normal light reflected from an object when a disturbance light signal having an emission frequency equal to or close to the emission frequency of at least one of the two optical signals is incident. Depending on the phase relationship when both the signal and the disturbance light signal overlap, the regular light signal is not received by the light receiving means, and as a result, there is a possibility that the object detection cannot be performed properly. For example, if the two signals overlap with a phase shift near the half wavelength of the emission frequency, the amplitudes of the two signals cancel each other and the optical signal level is lowered so that the reflected light is not received. Even if an object exists, it is falsely detected as non-existing.

  On the other hand, when the target location of the object to be detected is relatively wide, for example, in the case of a linearly long area, the light emitting means and the light receiving means are installed across the area, and the optical signal transmitted from the light emitting means A transmission type object detection device that can detect the presence or absence of an object in the entire region by setting an optical path so as to transmit the region is more suitable than a reflection type object detection device. However, if the detection target area is wide, there is a high possibility of erroneous detection due to the influence of ambient light from the above-described remote controller or the like.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reliably detect an object even in the case where an optical signal that causes disturbance from a remote controller or the like is incident on a transmission-type object detection device. It is in.

FEATURES configuration of an object detection apparatus according to the present invention for achieving the above object, a light emitting means for transmitting a plurality of optical signals different emission frequency from each other toward the presence planned portion of an object, that originated from the light emitting means A light receiving unit configured to receive light that has passed through a place where the object is present, and a light signal in which the light reception signal of the light receiving unit does not correspond to the light emission signal of the light emitting unit among the plurality of optical signals is excluded. And a discriminating means for discriminating the presence or absence of an object at the existing location based on the remaining optical signal , wherein the light emitting means transmits the plurality of optical signals as pulse waveforms having a predetermined time width. .

According to the above configuration, a disturbance light signal having a frequency that is the same as or approximate to the frequency of any one of the plurality of optical signals transmitted from the light emitting means interferes with the normal optical signal, and the normal light Even if the light that has passed through the location where the object is present is not properly received by the light receiving means, the remaining light signal that is not affected by the disturbance light signal is different because it is different in frequency from the disturbance light signal. The presence or absence of an object can be determined based on the signal.
That is, with reference to FIG. 2, in the case where an object does not exist at the planned location (A), one optical signal (36 kHz) among a plurality of optical signals (two of 36 kHz and 40 kHz). Is excluded as an uncorresponding optical signal because the received light signal includes a signal other than the light emission signal, but the remaining optical signal (40 kHz) is excluded as a corresponding optical signal because the received light signal does not include a signal other than the light emission signal. The presence of the object can be determined by receiving the signal (40 kHz). On the other hand, in the case where an object is present at the planned location (B), one optical signal (36 kHz) is excluded as an uncorresponding optical signal as described above, but the received optical signal is emitted for the remaining optical signal (40 kHz). Since signals other than the signal are not included, the presence of the object can be determined by not receiving the optical signal (40 kHz) as the corresponding optical signal.

  Here, as a comparative example, when both of the plurality of optical signals are transmitted through the planned location and received, the absence of the object is determined, and both of the multiple optical signals are blocked at the planned location. The point that the object detection cannot be performed properly in the transmission type object detection apparatus configured to determine the presence of an object when no light is received will be described. That is, when an object does not exist at the planned location, for example, one of the disturbance light signal and the regular light signal overlaps with a phase shift near the half wavelength of the emission frequency, and the amplitudes of both signals cancel each other out. If the regular optical signal is not received, the absence of the object cannot be determined even if the remaining optical signal is received. On the other hand, when an object is present at the planned location, as shown in FIG. 2B, even if a plurality of optical signals are blocked at the planned location, the disturbance light signal is erroneously regarded as one of the regular optical signals. When the light is received, the presence of the object cannot be determined.

  Therefore, according to the present invention, there is provided a transmission-type object detection apparatus that can reliably detect an object even when a disturbance optical signal is incident from a remote controller or the like.

In addition, according to the above configuration, a plurality of optical signals having different light emission frequencies are transmitted as pulse waveforms having a predetermined time width, and the pulse waveform of the light emission signal is compared with the pulse waveform of the light reception signal by the discriminating means. When the time width of the waveform does not correspond to the time width of the pulse waveform of the light emission signal, the presence / absence of an object is determined based on the remaining optical signal after excluding the optical signal. For example, as illustrated in FIG. 2, one optical signal (36 kHz) is excluded because the time width of the pulse waveform of the light reception signal does not correspond to the time width of the pulse waveform of the light emission signal.
Therefore, a preferred embodiment of an object detection device that can easily and appropriately identify and exclude an optical signal affected by a disturbance light signal by comparing time widths of a plurality of optical signals transmitted as pulse waveforms. Is provided.

A further characteristic configuration of the object detection device according to the present invention is that the light emitting means repeatedly transmits the plurality of optical signals by changing the condition of the pulse waveform in the plurality of optical signals.
That is, the pulse waveforms of the light emission signal and the light reception signal are compared in a plurality of optical signals repeatedly transmitted with the pulse waveform conditions changed, and the pulse waveform conditions of the light emission signal and the light reception signal do not match in the plurality of optical signals. In some cases, it is assumed that a disturbance has been applied, and the mismatched optical signals are not used for the object detection process.
Therefore, a preferred embodiment of an object detection device that can further improve the reliability of object detection is provided by taking into account the condition of the pulse waveform that is changed in a plurality of optical signals that are repeatedly transmitted.

An embodiment of an object detection device according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the transmissive object detection device according to the present invention includes a light emitting means 1 for transmitting a plurality of optical signals having different light emission frequencies to a predetermined location SY of an object, and the light emitting means 1. A light receiving means 2 for receiving light transmitted from a plurality of optical signals transmitted from the object existing location SY, and an optical signal in which the light receiving signal of the light receiving means 2 does not correspond to the light emitting signal of the light emitting means 1 among the plurality of optical signals. And a discriminating means 100 for discriminating the presence or absence of an object in the planned location SY based on the optical signal remaining after the removal.

  The light emitting means 1 transmits the plurality of optical signals as a pulse waveform having a predetermined time width. Specifically, the light emitting means 1 is an infrared light emitting diode as a single light emitting element 1A that sequentially transmits a plurality of optical signals (two infrared light signals with light emission frequencies of 36 kHz and 40 kHz) at time intervals. (IRLED). The light receiving means 2 includes two remote control light receiving ICs 2A and 2B having peak sensitivity for the two optical signals of 36 kHz and 40 kHz. Note that a disturbance optical signal (for example, a 36 kHz optical signal) is transmitted from the remote controller 10 for other equipment located near the object detection device.

  Light-emitting device 6 including the light-emitting element 1A and the light-emitting side microcomputer 3 that drives the light-emitting element 1A, and the light-receiving side microcomputer 4 that processes the light-receiving signals of the two light-receiving ICs 2A and 2B and the light-receiving ICs 2A and 2B 7 is disposed across the planned location SY, and the light emitting side microcomputer 3 and the light receiving side microcomputer 4 exchange signals with each other by wire or wirelessly. Each of the microcomputers 3 and 4 constitutes the discrimination means 100.

Next, some embodiments of the object detection processing by the determination unit 100 will be described.
[First Embodiment]
An example of the waveform of a signal in the first embodiment is shown in FIG. 2A shows a waveform when no object is present at the planned location SY, and FIG. 2B shows a waveform when an object exists at the planned location SY. In each of the following signal waveforms, the H level represents a no signal state and the L level represents a signal present state.

  2A and 2B, the optical signals of 36 kHz and 40 kHz having the same pulse time width t are transmitted from the light emitter at a time interval t1 (A). At this time, a 36 kHz optical signal that is a disturbance from the other remote controller 10 is transmitted at a timing unrelated to the regular 36 kHz optical signal from the light emitter (b). As a result, in FIG. 2A, the output signal waveform (c) of the light receiving IC 2A for 36 kHz is a waveform in which the 36 kHz optical signal from the remote controller 10 is superimposed on the regular 36 kHz optical signal, and the 36 kHz light emission signal ( B) includes a signal (time Δt) other than the signal (time width t) corresponding to (b). On the other hand, the output signal waveform (d) of the light receiving IC 2B for 40 kHz is not affected by the 36 kHz optical signal from the remote controller 10 that becomes a disturbance, and is a signal corresponding to the 40 kHz light emission signal (A) (time width t). Does not contain any other signal. Therefore, the discriminating means 100 excludes the 36 kHz optical signal and discriminates that no object is present at the planned location SY since the 40 kHz optical signal is received.

  On the other hand, in FIG. 2B, since the regular 36 kHz optical signal is blocked by the object, the output signal waveform (c) of the 36 kHz light receiving IC 2A becomes the waveform of the 36 kHz optical signal from the remote controller 10 and is 36 kHz. It includes a time Δt1 delay at the front end of the pulse with respect to a signal (time width t) corresponding to the light emission signal (A) and an extra time Δt2 at the rear end of the pulse. On the other hand, the output signal waveform (d) of the light receiving IC 2B for 40 kHz does not include a signal other than the signal corresponding to the 40 kHz light emission signal (A) (part of the time width t). Therefore, the discriminating means 100 excludes the 36 kHz optical signal and discriminates that an object is present at the expected location SY because the 40 kHz optical signal is not received.

[Second Embodiment]
In the first embodiment, the conditions of the pulse waveforms in a plurality of optical signals (36 kHz optical signal and 40 kHz optical signal) are the same. However, in the second embodiment, the light emitting means 1 includes a plurality of optical signals (36 kHz optical signal). And the 40 kHz optical signal), the conditions of the pulse waveform are changed, and the plurality of optical signals are repeatedly transmitted.
Hereinafter, examples of signal waveforms in the second embodiment are shown in FIGS. 3 to 5 in the case where an object is present at the planned location SY. Note that the conditions of the pulse waveforms in a plurality of optical signals can be set to various conditions other than the example shown here.

  FIG. 3 shows that a 36 kHz optical signal having a time width t and a 40 kHz optical signal having a time width 2t are transmitted in that order at a time interval t1, and then a 36 kHz optical signal having a time width 2t and a 40 kHz optical signal having a time width t. In this order, the conditions of the pulse waveform transmitted at the time interval t1 are shown, and one piece of data is constituted by four all pulse signals. In FIG. 3, for the 40 kHz optical signal, each pulse signal changed to the time width 2t and the time width t corresponding to the light emission signal waveform appears in the light reception signal waveform, whereas for the 36 kHz optical signal, the time width t Since this pulse signal does not appear in the light emission signal waveform, the data is excluded from the data used for object detection.

  FIG. 4 shows a pulse transmitted by transmitting a 36 kHz optical signal having a time width t and a 40 kHz optical signal having a time width t in that order at a time interval t1, and then transmitting the 36 kHz optical signal and the 40 kHz optical signal by switching the order. Waveform conditions are shown, and one piece of data is composed of all four pulse signals. In FIG. 4, for a 40 kHz optical signal, a pulse signal having a time width t appears in the received light signal waveform in a reversed order, whereas for a 36 kHz optical signal, the time width of the first pulse signal that appears in the received light signal waveform is shown. Since it differs from the time width t in the light emission signal waveform, the data is excluded from the data used for object detection.

  In FIG. 5, a 36 kHz optical signal having a time width t and a 40 kHz optical signal having a time width t are transmitted at a time interval t1, and then the 36 kHz optical signal having a time width t and a 40 kHz optical signal having a time width t are transmitted at time intervals. The condition of the pulse waveform transmitted at t2 (t1 <t2) is shown, and one piece of data is composed of four all pulse signals. In FIG. 5, the time interval t4 between the first 36 kHz optical signal and the 40 kHz optical signal in the received light waveform is different from the time interval t1 in the light emission waveform, and thus the data is excluded from the data used for object detection.

[Another embodiment]
In the above embodiment, two optical signals having a light emission frequency of 36 kHz and 40 kHz are used as a plurality of optical signals having different light emission frequencies. However, other light emission frequencies other than 36 kHz and 40 kHz may be used. Three or more optical signals having different values may be used.

  In the above embodiment, the light emitting means 1 is configured by a single light emitting element 1A. In addition to this, the light emitting means 1 is configured by a plurality of light emitting elements that transmit optical signals of each light emitting frequency, and each optical signal is transmitted. You may comprise so that light-receiving IC which comprises the light-receiving means 2 can light-emit simultaneously.

  In the above embodiment, the light receiving means 2 is constituted by a remote control light receiving IC having a frequency identification function. In addition to this, a plurality of photodiodes or phototransistors and a band-pass filter that passes only an optical signal of each frequency are provided. By configuring the light receiving means 2 in combination, it is possible to realize a function equivalent to that of a light receiving IC for remote control.

  The object detection apparatus of the present invention can be used for detection of various objects in various facilities. As an example, in an automatic opening and closing garage, the object detection device of the present invention is installed so that the front area of the garage door is the detection target area (the planned location of the object), and the front of the automobile is the garage It can be used for the purpose of automatically opening the door by detecting that it is located in front of the door.

1 is a conceptual diagram showing the overall configuration of a transmission type object detection device according to the present invention. The time chart which shows the waveform example of the signal in 1st Embodiment The time chart which shows the waveform example of the signal in 2nd Embodiment The time chart which shows the waveform example of the signal in 2nd Embodiment The time chart which shows the waveform example of the signal in 2nd Embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting means 1A Light emitting element 2 Light receiving means 100 Discriminating means SY Presence location

Claims (2)

A light emitting means for transmitting a plurality of optical signals having different light emission frequencies to an intended location of the object;
A light receiving means for receiving the light transmitted from the plurality of optical signals transmitted from the light emitting means through a predetermined location of the object;
A discriminating unit that discriminates whether or not an object is present at the planned location based on an optical signal that remains after excluding an optical signal in which the light receiving signal of the light receiving unit does not correspond to the light emitting signal of the light emitting unit among the plurality of optical signals. door is provided,
An object detection apparatus in which the light emitting means transmits the plurality of optical signals as a pulse waveform having a predetermined time width . The object detection apparatus according to claim 1 , wherein the light emitting unit repeatedly transmits the plurality of optical signals while changing a condition of the pulse waveform in the plurality of optical signals .

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