JPS61249198A - Sensor unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sensor device comprising a dark field warning device and a length measuring device or a speed detecting device.

2. Description of the Related Art Conventionally, so-called dark-field alarm devices using infrared rays have been used as devices for monitoring darkness such as night security. In other words, the infrared rays emitted from the light emitting part are received by a light receiving part far away, and if something interrupts the gap between the light emitting part and the light receiving part, the light receiving part detects this, or the infrared rays emitted from the light emitting part are detected. A light receiving unit detects infrared rays that are reflected by an object and issues an alarm.

In this dark field alarm device, G is generally used as a light emitting part.
An aAs light emitting diode or the like is used, and near-infrared rays with a wavelength of around 1 μm are used. In addition, as an infrared sensor that captures infrared rays at the light receiving part, for example, a pyroelectric material such as PbTi0a, an infrared light guiding material such as PbS, InSb, etc. is used, but this is inside the light receiving window made of germanium, silicon, etc. The infrared rays pass through this light receiving window and reach the infrared sensor.

On the other hand, as a device for measuring the distance to a distant object or moving object, there is a pulse radar that emits microwaves, captures reflected waves from the object, and calculates the distance from the phase of the reflected waves. Further, as a device for detecting a moving object or its moving speed, there is a Doppler effect using electromagnetic waves or ultrasonic waves, that is, a Doppler radar that calculates the speed from the amount of frequency change of reflected waves.

However, in recent years in the field of laser technology, especially with the development of carbon dioxide lasers that are highly energy efficient and can produce large outputs from several tens of W to several tens of kilowatts, pulse radar and Doppler radar that use far infrared rays with a wavelength of 1016 μm have been developed. has been devised.

Problems to be Solved by the Invention It would be very effective if the dark field alarm device was equipped with the length measurement function of a pulse radar or the speed detection function of a Doppler radar. However, by adding these functions, the device has multiple openings and the device becomes larger, which creates the problem of restrictions on where and how to install the device, and furthermore makes it difficult to move the device. The problem also arises.

In addition, near-infrared rays used for dark-field warnings, microwaves and far-infrared rays used for length measurement and speed detection are electromagnetic waves in wavelength ranges that are invisible to the human eye, so equipment with these functions should be installed. The actual alignment cannot be done directly by eye, but must be done indirectly by observing the electrical output. Therefore, there is a problem in that alignment requires a great deal of effort and time.

As one method to solve this problem, it is known to irradiate a laser beam in the visible light range in the same direction or parallel to the optical path of a measuring instrument, etc., and to position the measuring instrument, etc. using the irradiation spot. .

Therefore, it is desired to realize a compact sensor device that has functions such as dark field alarm, length measurement or speed detection, and moving object detection, as well as a function that allows easy positioning. , the sensor device has one opening, and inside is a near-infrared sensor for dark-field warning, a microwave or far-infrared sensor for length measurement, speed detection or moving object detection, and visible light for alignment. A sensor is installed, and through a window in the opening, near-infrared light with a wavelength of about 1 μm is emitted for dark-field warning, microwave or far-infrared light for length measurement, speed detection, and moving object detection, and visible light for positioning. It is necessary to irradiate or receive light. Further, the use of electromagnetic waves (light and radio waves) of different wavelengths for different measurements is also necessary in order to prevent interference between measurement electromagnetic waves.

However, germanium and silicon, which are the materials for the light receiving window of conventional dark-field alarm devices, are
The transmittance is high in the near-infrared region (wavelength 0.76 to 2.5 μm) including μm, but the wavelength of carbon dioxide laser is 1066 μm.
It has a transmission spectrum in which it has low transmittance in the far infrared region (wavelength of 2.5 μm or more) including the microwave region, and also has difficulty passing through the microphone b-wave region. Therefore, if a light-receiving window made of germanium or silicon is used, most of the energy of the microwave and carbon dioxide laser light will be absorbed by the light-receiving window.

Therefore, the energy captured by the microwave sensor and the far-infrared sensor is small, making it difficult to perform highly sensitive length measurement, speed detection, or moving object detection.

Therefore, an object of the present invention is to provide a new sensor device equipped with a dark field alarm function, a length measurement or speed detection/moving object detection function, and a position alignment function, and which is capable of high-sensitivity measurement. The object of the present invention is to provide a window material that enables detection.

Means for Solving the Problems The sensor device of the present invention provides a common opening for the first, second, and third sensors, a window plate is installed in this opening, and the window plate is connected to the first sensor. , made of a material that is transparent to all detection wavelength ranges of the second and third sensors.

In a preferred embodiment of the present invention, the window plate is made of ZnS.

Further, the second sensor is a microwave sensor, and the thickness of the window made of ZnS is approximately equal to an integral multiple of half the wavelength of the microwave detected by the microwave sensor in ZnS.

Further, the second sensor may be a sensor for carbon dioxide laser light. Furthermore, the ZnS constituting the window plate has been uniformized.

Isaku J With this configuration, near-infrared light with a wavelength of about 1 μm can be detected by the first sensor, microwave or far-infrared light by the second sensor, and visible light by the third sensor. .

Therefore, the first sensor enables dark field monitoring, the second sensor enables length measurement, moving object detection, and speed detection, and the third sensor enables positioning.

In order to provide these three functions as a compact sensor device, it is important to use a window material that allows light to pass from visible light to far infrared or microwave regions. Materials that allow far infrared rays to pass, especially wavelengths around 10.6 μm, and also allow microwaves to pass through are hardly known. Based on our actual measurements, ZnS is the first material to be confirmed to efficiently transmit everything from visible light to microwaves. In particular, ZnS that has been uniformized by heat treatment or the like has a characteristic that its transmittance from the visible light region to the near-infrared light region is high.

Thickness 5.5 after uniformization treatment shown in Figures 3 and 4 respectively
The transmission spectrum of a 2nS plate of mm in the infrared light region and visible light region is shown.

As is clear from Figure 3, ZnS has a wavelength of approximately 15 μm.
It transmits infrared rays shorter than that of the carbon dioxide laser beam, and exhibits particularly high transmittance near the wavelength of carbon dioxide laser light of 10.6 μm.

Moreover, it can be seen from FIG. 4 that visible light having a wavelength of 0.4 to 0.8 μm is also efficiently transmitted.

In addition, Table 1 shows the frequency of ZnS plates of 6 types of thickness 6G
Microwave characteristics for tlz, 12GHz, and 17GHz are shown. Here, ε is the dielectric constant, and tan δ is the loss coefficient of the dielectric constant. As described above, it can be seen that the ZnS plates of various thicknesses have a small loss coefficient in each frequency band, that is, the lost energy is small, so that microwaves are efficiently transmitted.

Table 1 also shows that the wavelength λ of the microwave used in ZnS is several meters.
Since the thickness is approximately the same as the thickness of the ZnS plate used for the window of the opening, the phenomenon of interference cannot be ignored. That is, in FIG. 5, the microwave incident on the ZnS plate generates a reflected wave 31 on the top surface 35, and
The wave that has passed through is reflected again at the lower surface 34 and returns as a reflected wave 32. Therefore, the composite reflected wave 3 by the ZnS plate
3 is represented by the sum of the reflected waves 31 and 32. Now, as is well known, the phases of the reflection coefficients at the upper surface 35 and the lower surface 34 are reversed, resulting in equal amplitude and opposite phase, so the condition for minimizing the combined reflected wave 33 due to interference is that the reflected waves 31 and 32 The difference in propagation distance is an integral multiple of the wavelength, and is given by the following equation.

2d=nλ...(1) However, d: Thickness of ZnS plate λ: Wavelength of microwave in ZnS n: Integer Therefore, from formula (1), thickness d of ZnS plate is The ZnS plate transmits microwaves most efficiently when the wavelength is an integral number n times half of the wavelength λ.

Note that similar conditions can be obtained in an analysis that takes into account multiple reflections within the ZnS plate.

Using relative dielectric constant ε, frequency 68Hz, 12GHz1
The half wavelength λ/2 of the microwave in ZnS at 17 GHz is approximately 9.0 mm and 4.5, respectively.
mm, 3.1 mm, and the thickness of each sample in Table 1 is 9, Om.
m 18. Omm, 26.9mm.

24, 9mm, 30.8mm, 36.9mm are (1
) is set to a value that satisfies the formula.

Note that, as a result of transmittance measurement, the transmission spectra of visible light and infrared rays do not change much due to changes in the thickness d of the ZnS plate. Therefore, the thickness d of the ZnS plate is determined by the frequency f of the microwave used.

That is, when carbon dioxide laser light is used for length measurement or moving body detection, the thickness d of the ZnS plate may be any value.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a configuration diagram of an opening of a sensor device according to an embodiment of the present invention. Window l is made of ZnS, visible light,
It transmits infrared rays and microwaves and protects the infrared sensor 2, microwave sensor 3, and visible light sensor 4. And its thickness is about 9. It is Omm. A charge-coupled device (CCD) was used as the infrared sensor 2.

As the visible light sensor 4, a silicon photodiode having particularly high sensitivity around a wavelength of 0.633 μm was used.

The holder 5 is a member for supporting the window 1. After aligning the device using visible light with a wavelength of 0.633 μm from a He-Ne laser, we conducted experiments using infrared light with a wavelength of about 1 μm and microwaves at 6 GHz from a GaAs light emitting diode. 100
An infrared sensor detects an object that is m away, and this one
A distance of 0.00 m could be measured by the microwave sensor 3.

Example 2 FIG. 2 is a diagram showing the configuration of the opening of the second embodiment.

In this second embodiment, a carbon dioxide laser light sensor 6 is installed in place of the microwave sensor 3 in the embodiment shown in FIG. The carbon dioxide laser light sensor 6 has particularly high sensitivity around a wavelength of 1006 μm. As a result of experiments using infrared laser light with a wavelength of 10.6 μm from a carbon dioxide laser and infrared light with a wavelength of about 1 μm from a GaAs light emitting diode, the infrared sensor 2 detects objects that are about 100 m away at night, and this 100 m
It was possible to measure the distance by using the carbon dioxide laser light sensor 6.

Note that in Example 1.2 above, distance was measured using microwaves or carbon dioxide laser light, but speed detection and
A similar effect can be obtained by detecting a moving object.

Further, in the above embodiment, a GaAs light emitting diode was used for the infrared sensor for dark field alarm, but an InP light emitting diode, a Ga5h light emitting diode, a CdSnP2
It is also possible to use light emitting diodes with different emission wavelengths, such as light emitting diodes.

Furthermore, although the microwave used for distance measurement etc. uses the GHz band, other wavelength ranges can also be used. However, as the wavelength of the microwave becomes longer, the thickness of the window plate must be increased, which also increases the attenuation.

Therefore, the microwave to be used is determined within a range that does not make the window plate too thick.

Further, the far-infrared laser used for distance measurement etc. is not limited to a carbon dioxide laser, but also gas lasers such as N20, CN, NH3, etc., and semiconductor lasers such as Pb8-5eTe and pbSnSSe can be used.

As a light source for alignment, in addition to the Ie -Ne laser, a gas laser such as argon or Kr that oscillates laser light in the visible light range, a solid laser such as Cr+3-Al□O8, or a solid laser such as GaSe, Ga A+c P [1- II
) or other semiconductor lasers may be used.

Furthermore, in one of the above embodiments, near-infrared light is used for dark-field alarm and far-infrared light is used for distance measurement, etc., but by reversing this, far-infrared light is used for dark-field alarm. Outside light may be used, and near-infrared light may be used for distance measurement, etc.

As described in detail, the present invention has a dark field alarm function, a function of measuring and detecting the distance to an object or the speed of a moving object with high sensitivity, and a positioning function. A small sensor device is realized.

Therefore, it would be very effective to apply the sensor device according to the present invention to a nighttime dark field alarm device for building management, etc.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the aperture of a sensor device according to one embodiment of the present invention, FIG. 2 is a block diagram of another embodiment, FIGS. 3 and 4 are transmission spectra of ZnS, and FIG. It is a figure explaining the interference of the microwave by a ZnS board. (Main reference numbers) 1...Window, 2...Infrared sensor, 3...Microwave sensor,

Claims (6)

[Claims] (1) A first sensor that has its highest sensitivity in a first wavelength range in the infrared range, and a second sensor that has its highest sensitivity in a second wavelength range that is different from the first wavelength range in a wavelength range that includes the radio wave range and the infrared range. A sensor device comprising a second sensor whose wavelength is a wavelength of maximum sensitivity, and a third sensor whose highest sensitivity wavelength is a third wavelength range in the visible light range, the sensor device having one opening and a sensor provided in the opening. It has a window board,
The window plate is made of a material that is transparent in the first, second, and third wavelength ranges, and the first, second, and third sensors are respectively installed inside the opening. A sensor device characterized by: (2) The sensor device according to claim 1, wherein the second sensor is a microwave sensor. (3) The sensor device according to claim 2, wherein the thickness of the window plate is approximately equal to an integral multiple of half the wavelength of the microwave used in the microwave sensor in the window plate. (4) The sensor device according to claim 1, wherein the second sensor is a carbon gas laser beam sensor. (5) The sensor device according to any one of claims 1 to 4, wherein the window plate is made of ZnS. (6) The sensor device according to claim 5, wherein the ZnS is homogenized.