JPS5871405A - Distance measuring device - Google Patents

Abstract

PURPOSE:To measure a plurality of the distances highly accurately, by modulating electromagnetic waves whose wavelengths are 0.5mum or more and 5mum or less, by frequencies of 100kHz or more and 5MHz or less, and comparing the phase delays corresponding to the time length during which the electromagnetic waves go to and return from the object to be measured with a reference signal. CONSTITUTION:The electromagnetic waves, whose wavelengths are 0.5mum or more and 5mum or less, are generated by light emitting diode 2, and modulated by frequencies of 100kHz or more and 5MHz or less from an oscillator 1. Reference luminous flux 4a and reflected luminous flux 4c are received by light receiving elements 6 and 7. The phase is delayed in correspondence with the time length during which the electromagnetic waves go to and return from the object to be measured. The phase delays corresponding to the distances 2m, 5m, and 8m are imparted to reference signal generating means 101-10n. The outputs from phase difference detectors 111-11n become the voltages corresponding to the phase differences between the reference signal and the measured signal. When both distances are agreed, the outputs become zero. This fact is detected by zero detectors 12, and converted by a signal converting means 13 as a distance signal, and displayed by a display 14. Therefore the distances of 2m, 5m, and 8m can be measured accurately.

Description

[Detailed description of the invention] The present invention relates to a distance measuring device that uses electromagnetic waves.

This type of distance measuring device measures distance based on the phase difference between the electromagnetic wave output from the electromagnetic wave generating device and the reflected electromagnetic wave that is reflected by the electromagnetic wave from the object to be measured. Conventionally, in order to improve distance performance and accuracy, high frequencies of 10 to 100 or more have been used to modulate electromagnetic waves, but at such high frequencies, electromagnetic wave generating means and radio wave receiving means are very difficult to use. However, there was a drawback that the signal processing circuit became complex and quadrivalent.

As a result of prototyping and research, the applicant has found that a relatively low variable frequency of several hundred KHz to several tens of kilohertz is sufficient when measuring, for example, the focal length of a camera or the inter-vehicle distance of a vehicle. A book that can withstand use,
Furthermore, it has been found that by using four low waves, it is possible to downsize the electromagnetic wave generating means and the like, and to simplify and reduce the cost of the signal processing circuit. In this case, the modulation frequency is 1001
Below 0h, the phase difference is too small and the detection integration is unusable, making it unusable.If it is above 0h, the operating limit frequency of a general-purpose integrated circuit (IC) is exceeded, and a special integrated circuit is required, which is expensive. becomes. The wavelength of electromagnetic waves is 0.
There are light emitting diodes (Ia) and other devices that emit light with less than 5 digits, but they have not reached the point where they are commercially available. Therefore.

It's expensive. In addition, it was found that the light emitting means becomes large when it is 5 an or more.6 The present invention was proposed in view of the above, and it can be used quickly and with high a
To provide a distance measuring device capable of measuring distances in a plurality of distance zones at once with a simple configuration and at low cost.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the first embodiment.

1 is an oscillator as a radio wave modulation means that oscillates at a frequency of 100 KHz or more and 5 MHz or less; 2 is a light emitting diode as a middle stage of % magnetic wave generation that generates an electromagnetic wave with a growth of 0.5 circles or more and 5 p or less; 3 is a light emitting diode 2; A light splitter placed near the front side splits the light 4 from one light emitting diode 2 into a reference light beam 4a and an irradiation light beam 4b. The object to be measured 5 is irradiated with this irradiation light beam 4b. Reference numeral 6 denotes a light receiving element for receiving the reference light beam 4a, 7 a light receiving element for receiving the reflected light beam 4c from the fixed object 5, 8 and 9 AC amplifiers for amplifying the outputs of the light receiving elements 6 and 7; Reference numerals 101 to 10n are reference signal generating means made up of delay elements, which give a desired phase delay to the output of the AC amplifier 8 to generate reference signals corresponding to a plurality of distances to objects to be measured. 111 to 11n are phase difference detection means 121 to 12 for detecting a phase difference between the output of the AC amplifier 9 and the output of the reference signal generation means 101 to 1 inch;
n is a zero detector 13 that detects that the output of each phase difference detection means 111 to 11m is zero; and zero detector 121 to 12n.
14 is a signal converting means for converting the output (1 or 0) into a distance signal.

The phase difference detection means 10 is manufactured by RCA, for example.

7 AIDS Locked Loop (Phase * Locked @ Loop specified by “CD4046A”)
It is also possible to use the phase difference detection circuit section in ).

In addition, the 9 light emitting diodes 2 have means for generating light waves ranging from the visible range to the infrared range, such as a semiconductor laser, and the light waves are generated at 100
It may be an element or device that can be modulated at frequencies ranging from a few MHz to several MHz. The AC amplifiers 8 and 9 may include bandpass filters that pass only frequencies near the modulation frequency.

By the way, the time Δt required for the electromagnetic wave to travel the distance to the object to be measured 5 at the speed C can be expressed as Δt=2L/C 0 Also, when the electromagnetic wave is modulated at the frequency f, the time Δt is determined by the time Δt mentioned above. Is the phase delay R of frequency f t? t x f x 560 = 2L x t x
It can be expressed as 560/C ('').0 So, now, the distance to the object to be measured 5 is 2 m.

5ms 8m, and electromagnetic waves are light waves, that is, speed [C-5X
10' rrim@a *light 11 Ohen 1i111
Fi! If tl t& number f -50010h, Δ
P is 2.4°, 6.0°, and 9.6°, respectively.

The reference signal generating means 101 generates a frequency of 500 KHz by 2.
4°, the same 102 has a frequency of 500 KHz at 6.0. When the frequency of 500 m is selected to give a 9.6 phase delay, the outputs of the zero phase difference detectors 111 to 11m are the same as the reference signal given one phase delay by the reference signal generating means 101 to 10n. The voltage corresponds to the phase difference between the reflected light beam 4c' from the object to be measured 5 and the measurement signal demodulated into an electrical signal.

FIG. 2 shows that the phase difference detection means 111 to 11n, for example,
The output of the phase difference detector 111 is measured with the horizontal axis representing the phase difference of the created polarization input with respect to the phase of the reference signal input in the case of the phase difference detection circuit section in the 7-eighth tube tract loop. The phase difference between the signal and the reference signal to which the reference signal Il1 generating means 101 gives a phase difference of 2.4 is zero, that is, the distance to the object to be measured 5 is 2.4. When m, it becomes zero. Zero detector 12 connected to the output of phase difference detector 111
1. If we change the configuration so that when the input is zero, the output is 1'', and when the input is other than zero, the output is ``0'', the distance at the object to be measured 5t will be 2.
When m, the output is 1, and under some other conditions, it becomes 0. Similarly, when the distance to the object to be measured is 5 m, only the output of the zero detector 122 is 1'', and when the distance is 8 m, only the output of the zero detector 123 is 12.

The output of the zero detectors 121 to 12n is converted into a distance signal by R15 during signal conversion, and the distance to the object to be measured 5 is displayed by the acupuncture indicator 14. Instead, a camera lens drive circuit is installed.
It is also possible to control this drive circuit with the output from the signal conversion means 11 to automatically adjust the focus.

In the example in Figure 1 above, the distance measurement zone is set to 3 points, but the distance measurement zone can be increased or decreased depending on the need, and it is sufficient to give each one a phase delay according to the desired distance. 0 again. ? The difference in the amount of phase delay of the single signal generating means 101 to 10n corresponds to the distance change value obtained by the phase difference detector @1.
11@11 is configured to find the minimum value of the output, and it is easy to get 0. Depending on the configuration of the reference signal generating means 101 to 10n and the phase difference detecting means 111 to 11n, distance measurement may be performed by determining the maximum value.

FIG. 3 shows another embodiment of the device of the present invention.

FIG. 1 shows the light splitting riI5. The reference light beam 4a is received by a light receiving element 6. AC amplifier 8 that amplifies the output of this light-receiving confectionery
9 is omitted, and instead of the electric signal of frequency f from the oscillator 1, the 1 light emitting element 2. Photodetector 7 and amplification #! 9, etc., and the phase delay amount of frequency f caused by the desired distance to the object to be measured, a phase lag corresponding to the distance to the object to be measured is given, and the position is used as a reference signal. O supplied to the phase difference detection means 111 to 11n, the subsequent operations from this phase difference detection means are the same as those in the m1 diagram above, so the explanation will be omitted. Electromagnetic waves of 5 ropes or less with a frequency of 100KH, which is sufficiently lower than the electromagnetic wave j.
Modulation is performed above z and below 51 For example, by applying the distance measuring device developed in this invention to a camera, it is possible to obtain a distance measuring device that can perform distance measurement with a simple configuration, and to obtain a very short distance. It is important to be able to perform highly accurate distance measurement on time, and the obtained distance signal is used to control the amount of flash light emitted, the aperture value of the photographic lens, etc., and adjust the distance according to the subject distance during flash photography. If the distance device of the present invention, which is capable of photographing with a blinding light, is used for measuring the distance between vehicles, the safe distance between vehicles can be measured in a short time, improving safety.

[Brief explanation of drawings]

i@1 Figure 1 is a block diagram showing the first embodiment of the present invention, Figure 2 is a diagram showing the relationship between phase difference and output voltage, and Figure 3 is a block diagram showing the second embodiment of the present invention.01 Ha-oscillation! , 2 is a light emitting diode, 5 is a light splitter, 5 is an object to be measured, 6 and 7
is a light receiving element, 8 and 9 are AC amplifiers, and 101 to 10n・1
51 to 15n are reference signal generating means, and 111 to 11n are phase difference detection means. 121-12njL zero detection gain, 16 signal conversion means. 14 is a display.

Claims (1)

[Claims] (1) an electromagnetic wave generating means for generating an electromagnetic wave with a wavelength of 0.5 kHz or more and 5 MHz or less, and an electromagnetic wave modulating means that controls the electromagnetic wave generating means to modulate the electromagnetic wave at a frequency of 100 KHz or more and 5 MHz or less; a demodulating means for demodulating the electromagnetic wave reflected from the object to be measured of the Joki electric wave into an electrical signal;
a plurality of reference signal generating means for generating reference signals corresponding to various distances to the object to be measured by immersing in the output of the electromagnetic wave or the electromagnetic wave modulating means that does not depend on a fixed object; :,
A plurality of phase difference detection means for detecting the phase difference between the two electrical signals with respect to the reference signal, and 11 for individually detecting that the output of these phase difference detection means is zero! Number zero detection means. #J distance device 0 characterized by comprising signal conversion means for converting the phase signal from the zero detection means into a distance signal.