JP2010223714A - Doppler sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Doppler sensor capable of ensuring both the width of a detection range and the sensitivity to a solid angle near a vertical lower side direction, while suppressing increase in the manufacturing cost and enlargement. <P>SOLUTION: A transmission signal from an oscillator 11 is inputted alternately by a changeover switch 13, to one of a first transmission antenna 12a for transmitting a transmission wave to a first detection range including a vertical lower side and a second transmission antenna 12b for transmitting the transmission wave to a second detection range which includes the vertical lower side and has a smaller solid angle than the first detection range. While the first relatively wide detection range is ensured by the first transmission antenna 12a, the sensor can ensure the sensitivity, by using the second transmission antenna 12b corresponding to the second detection range which is made narrower than the first detection range, with regard to the vertical lower side. Additionally, increase in the manufacturing cost and enlargement can be suppressed, by making the oscillator 11 and a signal processing circuit 2 used in common for the first and second detection ranges. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a Doppler sensor.

  Conventionally, as shown in FIG. 4, the detection range Z is irradiated with radio waves (transmission waves), and a transmission / reception circuit 1 that receives the radio waves (reflection waves) reflected by the detection ranges Z is provided. A Doppler sensor for detecting a moving object such as a human body M using a Doppler signal obtained from a wave is provided. For example, millimeter waves are used as the radio waves. This type of Doppler sensor is used for detecting the human body M in, for example, an illumination system that switches on / off the light source in accordance with detection of the human body M (see, for example, Patent Document 1).

  As another sensor for detecting the human body M, for example, there is a heat ray sensor for detecting a heat ray radiated from the human body M, but the Doppler sensor has an advantage that it can detect a human body M at a long distance compared to the heat ray sensor. Therefore, it is suitable for a usage pattern in which the ceiling CE is attached to the ceiling CE in a building having a high ceiling CE as shown in FIG.

JP-A-10-31066

  Here, the Doppler sensor utilizes the fact that the Doppler frequency, which is the difference in frequency between the transmitted wave and the reflected wave, is proportional to the speed of change of the distance between the transmission / reception circuit 1 and the human body M (moving object). A human body M (moving object) is detected. Therefore, the moving direction of the human body M (moving object) moving on the floor surface FL is a direction in which the angle θ formed with respect to the straight line connecting the transmission / reception circuit 1 and the human body M is approximately 90 °, that is, the actual human body M. The sensitivity is relatively low with respect to the solid angle near the vertical direction, which is the direction in which the change speed Vcos θ of the distance to the transmission / reception circuit 1 becomes very small for the moving speed V. If the detection range Z is narrowed to increase the intensity of the radio wave irradiated per solid angle, the sensitivity is improved. However, the detection range Z is narrowed.

  In addition, it is conceivable to secure the sensitivity to the solid angle near the vertically downward direction with another type of sensor, but this increases the manufacturing cost and the size.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is to secure both a wide detection range and sensitivity to a solid angle near the vertical direction while suppressing an increase in manufacturing cost and an increase in size. An object of the present invention is to provide a Doppler sensor that can be used.

  The invention of claim 1 is a Doppler sensor that detects a moving object that moves on the floor surface, and is arranged at a position higher than the moving object, and includes a predetermined first detection range including a vertically lower part and a vertically lower part, and Movement that exists in the first detection range or the second detection range by transmitting radio waves to the second detection range whose solid angle is smaller than the first detection range and receiving radio waves from the first detection range and the second detection range. A transmission / reception circuit that generates an output including at least a Doppler signal having a frequency corresponding to the speed of change of the distance to the object, and movement in the first detection range and the second detection range based on the Doppler signal included in the output of the transmission / reception circuit A signal processing circuit for determining the presence / absence of an object, and the transmission / reception circuit is an oscillator that generates a transmission signal of a predetermined transmission frequency and a radio wave of the transmission frequency when the transmission signal is input A first antenna unit that transmits a received wave to the first detection range, receives a reflected wave, and outputs a Doppler signal having a frequency that is the difference between the frequency of the transmitted wave and the reflected wave to the signal processing circuit; When a signal is input, a transmission wave, which is a radio wave having a transmission frequency, is transmitted to the second detection range, and a reflected wave is received to obtain a Doppler signal having a frequency that is the difference between the frequency of the transmission wave and the frequency of the reflected wave. A second antenna unit that outputs to the signal processing circuit, and a changeover switch that is controlled by the signal processing circuit and selectively inputs a transmission signal to one of the first antenna unit and the second antenna unit. .

  According to the present invention, the first antenna unit can detect a moving object having a relatively wide first detection range, but has a solid angle that is lower than the first detection range in the vertical downward direction where the sensitivity is relatively low. Sensitivity can be ensured by using the second antenna unit that transmits the transmission wave to the narrowed second detection range. In addition, since at least the oscillator and the signal processing circuit can be shared in the first detection range and the second detection range, compared to the case where the sensitivity relating to the vertical downward direction is ensured by another type of sensor such as a heat ray sensor, Increase in manufacturing cost and increase in size can be suppressed. Furthermore, the power consumption is reduced compared to a case where both the detection range and the sensitivity to the solid angle near the vertical direction are both secured by simply increasing the intensity of the transmission signal.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the second detection range is entirely included in the first detection range.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the signal processing circuit alternately inputs the transmission signal to the first antenna unit and the second antenna unit by periodically switching the changeover switch. It is characterized by.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the signal processing circuit waits until a predetermined delay time elapses without determining that there is a moving object in the detection range from the determination that the moving object exists in the detection range. Other than this period, the changeover switch is maintained in a state in which a transmission signal is input to the first antenna unit.

  According to the first aspect of the present invention, it is possible to detect a moving object having a relatively wide first detection range by the first antenna unit, but the lower vertical direction in which the sensitivity is relatively lower than the first detection range. Sensitivity can be ensured by using the second antenna unit that transmits the transmission wave in the second detection range in which the solid angle is narrowed. In addition, since at least the oscillator and the signal processing circuit can be shared in the first detection range and the second detection range, compared to the case where the sensitivity relating to the vertical downward direction is ensured by another type of sensor such as a heat ray sensor, Increase in manufacturing cost and increase in size can be suppressed. Furthermore, the power consumption is reduced compared to a case where both the detection range and the sensitivity to the solid angle near the vertical direction are both secured by simply increasing the intensity of the transmission signal.

It is a block diagram which shows embodiment of this invention. (A) (b) is explanatory drawing which shows the shape of each detection range by each same, (a) shows the shape seen from the horizontal direction, (b) is explanatory drawing which shows the shape on a floor surface. is there. It is a block diagram which shows the example of a change same as the above. It is explanatory drawing which shows the usage pattern of a Doppler sensor.

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

  The present embodiment is a Doppler sensor that detects a human body M (see FIG. 2A) as a moving object that moves on the floor surface, and as shown in FIG. And a signal processing circuit 2 for analyzing the output of the transmission / reception circuit 1 and determining the presence or absence of a moving object.

  As shown in FIG. 2A, the transmission / reception circuit 1 is arranged at a position higher than the height of a general human body M by being fixed to, for example, a ceiling CE having a height of 10 m, and includes a predetermined number including a vertically lower part. The first radio wave is transmitted to each of the first detection range Z1 and the predetermined second detection range Z2 including the vertically lower portion and having a solid angle smaller than the first detection range Z1 and entirely included in the first detection range Z1. It receives radio waves from the detection range Z1 and the second detection range Z2, and generates a Doppler signal having a frequency corresponding to the speed of change of the distance from the human body M existing in the first detection range Z1 or the second detection range Z2. .

  More specifically, the transmission / reception circuit 1 includes an oscillator 11 that generates a transmission signal of a predetermined transmission frequency (for example, 24 GHz) and a transmission wave that is a radio wave of the transmission frequency by inputting the transmission signal in the first detection range Z1. A first transmission antenna 12a that transmits to the second detection range Z2 by transmitting a transmission signal to the second detection range Z2, and a transmission signal A changeover switch 13 that is alternatively input to one of the first transmission antenna 12a and the second transmission antenna 12b, and a transmission wave that is transmitted from the first transmission antenna 12a is a radio wave that is reflected in the first detection range Z1. One reflected wave and a second reflected wave that is a radio wave reflected from the second detection range Z2 by the transmitted wave transmitted from the second transmitting antenna 12b are received and received respectively. Having a receiving antenna 14 into a signal, and a mixer 15 for mixing the received signal the transmission signal and the reception antenna 14 by the oscillator 11 is output is output. That is, the first transmitting antenna 12a, the receiving antenna 14 and the mixer 15 constitute a first antenna part in the claims, and the second transmitting antenna 12b, the receiving antenna 14 and the mixer 15 constitute a second antenna part in the claims. In the example of FIG. 3, the receiving antenna 14 and the mixer 15 are shared by the first antenna unit and the second antenna unit. By the way, a signal obtained by mixing (multiplying) a transmission signal and a reception signal is a sum of a Doppler signal having a difference between the frequency of the transmission signal and the frequency of the reception signal, and the frequency of the transmission signal and the frequency of the reception signal. A signal having a frequency (hereinafter referred to as “sum signal”) is added to each other, but the mixer 15 of the present embodiment is integrated with a low-pass filter that selectively attenuates the sum signal. The Doppler signal is output from the mixer 15 to the signal processing circuit 2.

  As shown in FIGS. 2A and 2B, each of the first detection range Z1 and the second detection range Z2 has a conical shape centered on a perpendicular line that is vertically lowered from the transmission / reception circuit 1. As shown in FIG. 2B, the contour of the first detection range Z1 on the floor surface and the contour of the second detection range Z2 on the floor surface are concentric with each other.

  The signal processing circuit 2 amplifies the Doppler signal output from the transmission / reception circuit 1 and outputs the amplified Doppler signal, and determines whether there is a moving object in the detection range based on the Doppler signal output from the amplification unit 21. And a determination unit 22. The amplifying unit 21 has a frequency characteristic that selectively amplifies the frequency of the Doppler signal corresponding to the moving speed of the human body M that is the moving object to be detected.

  In addition, the determination unit 22 compares the intensity (voltage value) of the Doppler signal with a predetermined determination threshold, determines that the human body M exists during a period in which the intensity of the Doppler signal is equal to or greater than the determination threshold, and the Doppler signal. It is determined that the human body M does not exist during a period in which the intensity of is less than the determination threshold, and an output corresponding to the determination result is generated. The determination result by the determination unit 22 is, for example, that a light source is turned on when a moving object (mainly human body M) is determined to exist in an illumination control system (not shown) that turns on and off an electrical light source, and the moving object This is used for control such that the light source is turned off when a predetermined lighting holding time has passed without being determined to be present.

  Further, the determination unit 22 also controls the change-over switch 13 until the determination that the human body M is not present after the determination that the human body M is present continues for a predetermined delay time. During the period (hereinafter referred to as “detection period”), the first transmission antenna 12a and the second transmission antenna 12b are controlled by periodically switching the switch 13 every predetermined switching time (for example, 0.5 msec). The switching operation of alternately inputting the transmission signal at each switching time is performed, and the transmission signal is input to the first transmission antenna 12a during a period other than the detection period (hereinafter referred to as “non-detection period”). Thus, a fixed connection operation of controlling the changeover switch 13 is performed. That is, the first detection range Z1 having a relatively large solid angle is maintained during the non-detection period. In the case where the present embodiment is used in the lighting control system as described above, when the lighting holding time and the delay time are made to coincide with each other, the detection period coincides with a period during which the light source continues to be lit, The detection period coincides with a period in which the light source is kept off.

  Since the transmission / reception circuit 1 and the signal processing circuit 2 as described above can be realized by well-known techniques, detailed illustration and description thereof will be omitted.

  According to the above configuration, the first transmitting antenna 12a can detect the human body M in the first detection range Z1 that is relatively wide, but the lower vertical direction where the sensitivity is relatively lower than in the first detection range Z1. Sensitivity can be ensured by using the second transmission antenna 12b that irradiates the transmission wave to the second detection range Z2 in which the solid angle is narrowed. Further, since only the second transmitting antenna 12b and the changeover switch 13 need be added, an increase in manufacturing cost and an increase in size are suppressed as compared with the case where the sensitivity related to the vertical downward direction is secured by another type of sensor such as a heat ray sensor. It is done. Furthermore, the power consumption is reduced compared to a case where both the detection range and the sensitivity to the solid angle near the vertical direction are both secured by simply increasing the intensity of the transmission signal.

  Note that the alternate switching operation may be performed regardless of whether it is the detection period or the non-detection period.

  Further, as shown in FIG. 1, two sets of receiving antennas 14a and 14b and mixers 15a and 15b may be provided in a one-to-one correspondence with the transmitting antennas 12a and 12b. In the example of FIG. 1, each transmitting antenna 12a, 12b constitutes antenna portions 1a, 1b together with a corresponding pair of receiving antennas 14a, 14b and mixers 15a, 15b, of which corresponding to the first detection range Z1. One of the two antennas is the first antenna unit 1a, and the other one corresponding to the second detection range Z2 is the second antenna unit 1b. In each antenna unit 1a, 1b, the output end of each mixer 15a, 15b is connected to the amplification unit 21 of the signal processing circuit 2, and one input end of each mixer 15a, 15b is connected to the corresponding receiving antenna 14a, 14b, respectively. The other input ends of the mixers 15a and 15b are connected to one switching contact of the selector switch 13 together with the corresponding transmission antennas 12a and 12b. In other words, each mixer 15a, 15b generates an output by receiving the transmission signal only during a period in which the transmission signal is input to the corresponding transmission antenna 12a, 12b, and outputs to the corresponding transmission antenna 12a, 12b. During a period in which no transmission signal is input, no output is generated regardless of the output of the corresponding receiving antennas 14a and 14b. Each of the receiving antennas 14a and 14b only needs to receive the reflected waves from the detection ranges Z1 and Z2 by the corresponding transmitting antennas 12a and 12b. Even in this case, since the oscillator 11 and the signal processing circuit 2 are shared by the two detection ranges Z1 and Z2, the sensitivity relating to the vertical downward direction is ensured by another type of sensor such as a heat ray sensor. In comparison, an increase in manufacturing cost and an increase in size can be suppressed.

DESCRIPTION OF SYMBOLS 1 Transmission / reception circuit 1a 1st antenna part 1b 2nd antenna part 2 Signal processing circuit 11 Oscillator FL Floor M Human body (moving object in a claim)
Z1 first detection range Z2 second detection range

Claims (4)

A Doppler sensor for detecting a moving object moving on a floor surface,
A first radio wave is transmitted to a predetermined first detection range including a vertically lower portion and a second detection range including a vertical lower portion and having a solid angle smaller than the first detection range. A transmission / reception circuit that receives radio waves from the detection range and the second detection range, and generates an output including at least a Doppler signal having a frequency corresponding to a speed of change of a distance from a moving object existing in the first detection range or the second detection range; ,
A signal processing circuit for determining the presence or absence of a moving object in the first detection range and the second detection range based on a Doppler signal included in the output of the transmission / reception circuit;
The transmission / reception circuit transmits a transmission wave that is a radio wave of the transmission frequency to the first detection range and receives a reflected wave by receiving the transmission signal and an oscillator that generates a transmission signal of a predetermined transmission frequency. A first antenna unit that outputs a Doppler signal having a difference between the frequency of the transmission wave and the frequency of the reflected wave to the signal processing circuit, and second detection of a transmission wave that is a radio wave of the transmission frequency by inputting the transmission signal A second antenna unit that transmits to a range, receives a reflected wave, and outputs a Doppler signal having a frequency difference between the frequency of the transmitted wave and the reflected wave to the signal processing circuit, and is controlled and transmitted by the signal processing circuit A Doppler sensor comprising: a changeover switch that selectively inputs a signal to one of the first antenna portion and the second antenna portion.   The Doppler sensor according to claim 1, wherein the entire second detection range is included in the first detection range.   3. The Doppler sensor according to claim 1, wherein the signal processing circuit inputs the transmission signal alternately to the first antenna unit and the second antenna unit by periodically switching the changeover switch.   The signal processing circuit sends a transmission signal to the first antenna unit except for a period from when it is determined that a moving object is present in the detection range until a predetermined delay time elapses without being determined that a moving object is present in the detection range. 3. The Doppler sensor according to claim 2, wherein the changeover switch is maintained in an input state.

Images