JP5543900B2 - Doppler sensor and lighting device using the doppler sensor - Google Patents

Description

  The present invention relates to a Doppler sensor and an illumination device using the Doppler sensor.

  2. Description of the Related Art Conventionally, there has been provided an illuminating device that detects a human body using a Doppler sensor and switches on / off a light source in accordance with the detection of the human body. In this type of lighting device, wasteful power consumption due to the user forgetting to turn off the light source can be suppressed as compared with the case where the light source is turned on / off manually.

  The Doppler sensor described above transmits (irradiates) a radio wave (transmission wave) such as a millimeter wave to a detection range, receives a radio wave (reflected wave) reflected in the detection range, and obtains an electric wave obtained by the reception. The signal is mixed (multiplied) with an electric signal having the same frequency as the transmission wave, and a Doppler signal is obtained by extracting a frequency band component corresponding to the moving speed of the human body from the obtained electric signal. By comparing the amplitude of the Doppler signal with a predetermined determination threshold, it is possible to determine the presence or absence of a human body within the detection range.

  Other sensors that detect the human body include, for example, a heat ray sensor (so-called PIR sensor) that detects heat rays emitted from the human body. Compared with a heat ray sensor, the Doppler sensor has an advantage that it is less susceptible to an environmental temperature change and an advantage that it can detect a human body at a relatively long distance. Due to the above advantages, the Doppler sensor is suitable for use in a place where the temperature changes more rapidly than in the case of a heat ray sensor, or for a usage pattern in which the Doppler sensor is attached to the ceiling in a building with a high ceiling.

  Further, in the Doppler sensor, the transmission of the transmission wave and the generation of the Doppler signal are often performed intermittently (see, for example, Patent Document 1).

JP 2008-249671 A

  Here, when a plurality of Doppler sensors are used simultaneously in a space that is narrower than the above-described detection range, the frequencies of the transmission waves (hereinafter referred to as “transmission frequencies”) of the Doppler sensors are different from each other. The At this time, the difference between the transmission frequencies is sufficiently large (for example, about several MHz) with respect to the width (several Hz to several hundreds Hz) of the frequency band extracted as the Doppler signal.

  However, in general, a circuit that transmits radio waves requires a certain time from the start of operation until the transmission frequency is stabilized.

  For example, in the case of two Doppler sensors used by being arranged close to each other, consider a case where transmission frequencies f1 and f2 at the time of stabilization are different from each other as shown in FIG. Even if the difference f1-f2 between the stable transmission frequencies f1 and f2 is sufficiently large, the transmission frequency f is increasing immediately after the start of the ON period of the intermittent operation of the Doppler sensor having a higher stable transmission frequency f1. The difference between the transmission frequency f and the Doppler sensor having a lower transmission frequency f2 at the time of stability temporarily falls within the above frequency band. Then, noise (interference) is generated in the signal level Va of the Doppler signal, which may cause erroneous determination.

  As a method of avoiding the above interference, a method of synchronizing the intermittent operations of the plurality of Doppler sensors so that the on periods of each other do not overlap with each other can be considered. However, since circuit components such as an oscillator that determine the transmission frequencies f1 and f2 have variations and aging deterioration, it is difficult to maintain the synchronization as described above for a long time.

  The present invention has been made in view of the above-described reasons, and an object of the present invention is to provide a Doppler sensor that hardly causes interference and an illumination device that uses the Doppler sensor.

  The Doppler sensor of the present invention transmits a radio wave to a predetermined detection range, receives a radio wave from the detection range, generates a Doppler signal from a transmission signal used for transmission and a reception signal obtained by reception. A transmitting / receiving unit that outputs, a human body determination unit that determines the presence or absence of a human body within the detection range using the Doppler signal, and a determination of whether or not there is an influence on the Doppler signal by periodic radio waves from an external source An influence determination unit, wherein the transmission / reception unit intermittently transmits radio waves to the detection range from the start of operation until the influence determination unit determines that the influence is present. When it is determined that there is the influence, transmission of radio waves to the detection range is made continuous.

  In the Doppler sensor, it is preferable that the transmission / reception unit intermittently transmits the radio wave to the detection range again after a predetermined continuous operation time has elapsed after the radio wave transmission to the detection range is continuous. .

  Moreover, the illuminating device of this invention is provided with the said Doppler sensor and the lighting part which controls the lighting state of an electrical light source according to the determination of the said human body determination part.

  According to the present invention, during a period in which the transmission / reception unit continuously transmits radio waves to the detection range, the transmission / reception unit transmits periodic radio waves from an external source such as another Doppler sensor. Interference with radio waves having a frequency lower than that of radio waves can be suppressed.

It is a block diagram which shows embodiment of this invention. It is explanatory drawing which shows each time change of the signal level Va of the Doppler signal in the same as the above, the signal level Vb of the output of a human body determination part, and the human body determination value binarized in the influence determination part. It is explanatory drawing which shows an example of the time change of the signal level Va of the Doppler signal produced | generated by one Doppler sensor with each higher transmission frequency f of two Doppler sensors which operate intermittently, and transmission frequency f1 at the time of stability. is there.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the lighting device 1 of the present embodiment transmits a radio wave to a predetermined detection range and a lighting unit 2 that turns on the electrical light source 20, and receives and transmits a radio wave from the detection range. The transmission / reception unit 3 that generates and outputs a Doppler signal from the transmission signal used for reception and the reception signal obtained by reception, and determines the presence or absence of a human body in the detection range based on the Doppler signal, and the lighting unit according to the determination result 2 and a human body determination unit 4 that controls 2. In general, the detection range at least partially overlaps the range illuminated by the light source 20.

  First, the transmission / reception unit 3 will be described. The transmission / reception unit 3 includes an oscillator 31 that generates a transmission signal having a predetermined frequency, a transmission antenna 32 that transmits a transmission wave, which is a radio wave converted from the transmission signal, to a detection range, and a transmission transmitted from the transmission antenna 32. A reception antenna 33 that receives a reflected wave that is a radio wave reflected in the detection range and converts it into a reception signal, and a mixed signal obtained by mixing the transmission signal output from the oscillator 31 and the reception signal output from the reception antenna 33 An output mixer 34 and an amplifier circuit 35 that extracts and amplifies a Doppler signal from the mixed signal and outputs the extracted signal to the human body determination unit 4 are provided. The amplifier circuit 35 includes, for example, a band pass filter and an amplifier circuit. The frequency band extracted as the Doppler signal in the amplifier circuit 35 is a frequency band (for example, 0 to 320 Hz) corresponding to the moving speed of the human body. In addition, the transmission / reception unit 3 normally performs an intermittent operation in which the transmission of the transmission wave and the output of the Doppler signal are intermittent by making the generation of the transmission signal by the oscillator 31 intermittent. Since the transmission / reception unit 3 as described above can be realized by a known technique, detailed illustration and description thereof will be omitted.

  For example, the human body determination unit 4 samples the signal level Va of the output of the Doppler sensor 3 (that is, the Doppler signal) at every predetermined sampling period and stores the signal level as needed, and stores it whenever the stored signal level reaches a predetermined number. The amplitude of the signal level Va (hereinafter referred to as “Doppler amplitude”) is obtained and stored by calculating 0.5 times the difference between the maximum value and the minimum value of the signal level Va. The signal level Va is deleted. Then, as shown in FIG. 2, if the Doppler amplitude is equal to or greater than a predetermined determination threshold Vth, the human body determination unit 4 determines that a human body is present in the detection range, sets the output Vb to the H level, and the Doppler amplitude is equal to the determination threshold Vth. If it is less than that, it is determined that there is no human body in the detection range, and the output Vb is set to L level. The lighting unit 2 continues the lighting of the light source 20 for at least a predetermined control delay time after the output Vb of the human body determination unit 4 becomes H level, and the duration in which the output Vb of the human body determination unit 4 is at L level. When the above control delay time is reached, the light source 20 is turned off. Note that the light output of the light source 20 may be reduced instead of turning off the light source 20 as described above.

  Next, the lighting unit 2 will be described. As the light source 20 to be lit by the lighting unit 2, a known electrical light source such as a fluorescent lamp or a light emitting diode can be used. When a fluorescent lamp is used as the light source 20, a known electronic ballast can be used as the lighting unit 2, and when a light emitting diode is used as the light source 20, a known DC power supply circuit is used as the lighting unit 2. be able to. In any case, since the lighting unit 2 can be realized by a well-known technique, detailed illustration and description are omitted.

  Furthermore, this embodiment includes an influence determination unit 5 that determines whether or not there is an influence on a Doppler signal by a periodic radio wave from an external generation source such as another Doppler sensor. That is, the transmission / reception unit 3, the human body determination unit 4, and the influence determination unit 5 constitute a Doppler sensor 6. The human body determination unit 4 and the influence determination unit 5 can be realized by a well-known technique using a microcomputer, for example.

  Here, when the intermittent operations of the two Doppler sensors that interfere with each other are both periodic (that is, the period is constant), noise generated in the signal level Va of the Doppler signal due to the interference also becomes periodic. Therefore, the influence determination unit 5 of the present embodiment determines the presence or absence of the above-described influence based on the periodicity of the determination result of the human body determination unit 4.

  If demonstrating it concretely, the influence determination part 5 will binarize and sample the output Vb of the human body determination part 4 regularly. That is, if the output Vb of the human body determination unit 4 is at the H level at the sampling timing, 1 is stored in the influence determination unit 5, and 0 is determined if the output Vb of the human body determination unit 4 is at the L level at the sampling timing. Stored in the unit 5. Further, the influence determination unit 5 immediately after the numerical value obtained by binarizing the output Vb of the human body determination unit 4 (hereinafter referred to as “human body determination value”) changes from 0 to 1 as described above. The period immediately before the human body determination value changes from 0 to 1 is regarded as one cycle, and the number of consecutive 1s and the number of continuous 0s are stored in the human body determination values. When the number of consecutive 1s and the number of consecutive 0s do not change over a predetermined number of cycles (for example, 4 cycles), it is determined that the above-described influence has occurred, and a predetermined output is input to the transmission / reception unit 3. To do.

  Then, when the predetermined output is input from the influence determination unit 5, the transmission / reception unit 3 thereafter transmits a transmission wave and outputs a Doppler signal until a predetermined continuous operation time (for example, 30 minutes) elapses. Each continuous operation is performed, and the intermittent operation is resumed after the continuous operation time has elapsed. When the predetermined output is input from the influence determination unit 5 after the intermittent operation is resumed, the continuous operation over the continuous operation time is performed again.

  According to the above configuration, the transmission frequency f is stable while the continuous operation is continued, and the transmission frequency f is not temporarily lowered like immediately after the start of the ON period in the example of FIG. Therefore, a radio wave that is a periodic radio wave from an external source and has a frequency lower than the stable transmission frequency of the transmission / reception unit 3 (for example, a transmission wave of another Doppler sensor that uses a lower transmission frequency f). The occurrence of interference between the two is suppressed.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Lighting part 3 Transmission / reception part 4 Human body determination part 5 Influence determination part 6 Doppler sensor 20 Light source

Claims (3)

A transmission / reception unit that transmits a radio wave to a predetermined detection range, receives a radio wave from the detection range, generates a Doppler signal from a transmission signal used for transmission and a reception signal obtained by reception; and
A human body determination unit that determines the presence or absence of a human body within the detection range using the Doppler signal;
An influence determination unit that determines whether or not there is an influence on the Doppler signal by periodic radio waves from an external source;
The transmission / reception unit intermittently transmits radio waves to the detection range from the start of operation until the influence determination unit determines that the influence is present, and the influence determination unit determines that the influence is present. Then, the Doppler sensor is characterized in that transmission of radio waves to the detection range is continuous. The transceiver unit, when the radio wave transmission predetermined continuous operation time after continuous of to the detection range has elapsed, again, claim 1, characterized in that the intermittent transmission of the radio wave to the detection range The described Doppler sensor. The Doppler sensor according to claim 1 or 2 ,
An illumination device comprising: a lighting unit that controls a lighting state of an electrical light source according to the determination of the human body determination unit.

Images