JPH06201822A - Supplementary device for recognition in dead area - Google Patents

Abstract

PURPOSE:To recognize the presence of an approaching vehicle at the dead area at the left and right rear parts without causing electromagnetic failure such as the malfunction of the electronic equipment of other vehicles and using one transmission/reception system. CONSTITUTION:The output signal of an oscillation part 14 is subjected to spectrum diffusion and modulation by a spectrum diffusion modulation part 6 and is sent to an antenna switcher 4 via a circulator 5. The antenna switcher 4 connects the circulator 5 to either an antenna 1 for right rear part or an antenna 2 for left rear part according to the direction instruction signal from a direction indicator 3. Also, the oscillation part 14 is activated when the direction indicator 3 outputs a direction instruction signal. A signal which is received by the antenna connected to the circulator 5 is demodulated by a spectrum diffusion demodulation part 10 via the circulator 5 and Doppler frequency is detected by a mixer 15 and then the approaching speed of a vehicle, etc., existing within an antenna radiation angle is calculated by a speed measurement part 16 which receives the Doppler frequency signal and is sent to a warning judgment part 17. The warning judgment part 17 gives a warning when the approaching speed reaches a dangerous speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION In the present invention, a car driver turns left,
The speed at which the approaching speed causes a danger such as a collision when there is a moving body such as an approaching vehicle in a direction that is a blind spot in the rear left direction or the rear right direction when viewed from the driver when making a right turn or changing lanes. In this case, the invention relates to a blind spot recognition assisting device that informs the driver of this by an alarm or the like.

[0002]

2. Description of the Related Art A conventional blind spot recognition assisting device for a vehicle corresponds to an antenna attached to a left rear blind spot and an antenna attached to a right rear blind spot as shown in FIG. Equipped with a transmitter / receiver and a speed measurement device, it transmits a single-frequency continuous wave or single-frequency pulse-modulated wave from an antenna and receives a reflected wave from a moving object within the radiation angle range of the antenna to receive Doppler frequency deviation. This was done by measuring the speed of the moving body by moving.

[0003]

However, since the conventional system uses a continuous wave or a pulse-modulated wave of a single frequency, the radiated energy density at that frequency is large, and the electronic equipment of the vehicle that receives the radiation radiates an electromagnetic wave. Therefore, there is a problem that it causes electromagnetic interference to the external environment such as malfunction. Further, since each antenna in each direction has a transmission / reception device, a speed calculation means, and an alarm device, there is a problem that the device occupies a large space and the cost of the device increases accordingly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a blind spot recognition assisting device which has a low electromagnetic interference to the external environment and a low installation cost in view of the above problems of the prior art.

[0005]

The present invention has the following means for achieving the above object. That is, the blind spot recognition assist device of the present invention includes a left rear antenna mounted on the vehicle body in the left rear blind direction of the vehicle; a right rear antenna also mounted in the right rear blind direction; A direction indicator that outputs a direction signal indicating left or right by operation; an antenna that switches the transmission path connection to the left rear antenna when the direction indicator is turned left, and to the right rear antenna when the direction is turned right A switching device; an oscillating unit that outputs a high-frequency signal when the turn signal indicates a left turn instruction or a right turn instruction; a spread spectrum modulation unit that spread spectrum modulates the high frequency signal from the oscillating unit; A spread spectrum demodulation unit for demodulating a signal; guiding a modulated output signal of the spread spectrum modulation unit to the antenna switching device,
A circulator that guides the received signal from the antenna switch to the spread spectrum demodulation unit; a Doppler frequency detection unit that receives the demodulated signal from the spread spectrum demodulation unit and detects the Doppler frequency of the received wave; and from the Doppler frequency, A speed measurement unit for calculating the speed of the moving body captured by any one of the antennas; a warning for receiving a speed signal from the speed measurement unit and issuing a warning when the speed signal reaches a preset critical speed It is characterized by comprising a judging section and.

[0006]

The operation of the blind spot recognition assisting device of the present invention having the above-mentioned means will be described below. In the present invention,
The high frequency signal generated by the oscillator is spread in spectrum by the spread spectrum modulator, so that the spectrum distribution is spread over a wide frequency range. This state is illustrated in FIG.

FIG. 2A is a diagram showing a spectrum of a high frequency signal (conventional transmission wave) generated in the oscillating unit, and FIG. 2B is a spectrum distribution diagram after being subjected to spread spectrum modulation. That is, while the spectrum distribution becomes wider than that in (a), the power at each frequency component can be reduced to near the noise level. As described above, since the electric power in each frequency component decreases, the possibility that an electronic device such as a vehicle that receives radio wave radiation will malfunction is reduced.

Further, since the oscillation of the oscillating unit is performed only when the direction indicator is set to the left direction or the right direction, electromagnetic interference is reduced as compared with the case of constant oscillation, and wasteful consumption of energy can be prevented.

Furthermore, since the connection of the circulator to the left rear antenna or the right rear antenna can be switched by the antenna switching device depending on the direction of the direction indicator, the transmission / reception including the spread spectrum modulation unit and the spread spectrum demodulation unit below the circulator. The function is one system, the occupied space can be saved, and the cost can be kept low as compared with the case where a plurality of functions are provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings of the embodiments. FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention. When the direction indicator 3 is operated to the right, the direction signal is sent to the antenna switching device 4, which connects the circulator 5 to the right rear antenna 1 and also sends the direction signal to the oscillator 14. The operation of the oscillator 14 is activated to generate a high frequency signal. Similarly, when the direction indicator 3 is operated to point to the left, the circulator 5 is connected to the left rear antenna 2, and at the same time, the oscillator 14 is also activated.

When the left / right direction is not instructed, the antenna switch 4 remains in the connection state in the last instructed direction, but the oscillating section 14 is not activated and the high frequency signal is not generated. The only difference between the left and right direction indications is the direction signal, the connection state of the antenna switch 4 and the difference between the operating antennas for the right rear antenna 1 and the left rear antenna 2. I will proceed with the explanation as if.

Therefore, the right rear antenna 1 is connected to the circulator 5, and this antenna transmits and receives radio waves. Since the direction is designated, the oscillating unit 14 is activated and a high frequency signal having a single frequency is output. This high-frequency signal is spread-spectrum modulated by the spread-spectrum modulator 6 and guided to the circulator 5. The spread spectrum modulation itself is a well-known technique, and is a modulation method in which the energy of each frequency is reduced by spreading the frequency component in a wide range.

The signal thus modulated passes through the circulator 5 and the antenna switching device 4, and the right rear antenna 1
Is emitted to the space. When another vehicle or the like exists within the radiation angle range of the antenna, the vehicle hits the vehicle, is reflected, and returns to the right rear antenna 1.

In this case, with respect to electromagnetic interference such as malfunction of electronic equipment of other vehicles, since the frequency component of the radio wave is distributed over a wide frequency range by the spread spectrum modulation, the energy at each frequency is reduced accordingly. Therefore, the electromagnetic interference can be eliminated by setting the degree of diffusion so that this level is lower than the level causing the electromagnetic interference.

The reflected wave returning to the right rear antenna 1 is input to the spread spectrum demodulation unit 10 via the antenna switch 4 and the circulator 5, and is demodulated into a high frequency signal before spread spectrum. In other words, the signal generated by the oscillator is radiated from the antenna without being subjected to spread spectrum modulation, and is demodulated into the same signal as when the signal is reflected back from the vehicle or the like and returned.

When a vehicle or the like that has reflected radio waves is moving, the frequency of the reflected wave is shifted by the Doppler frequency due to the Doppler effect. That is, when the vehicle or the like is approaching, the frequency of the reflected wave is higher than the transmission frequency by the Doppler frequency, and when the vehicle or the like is moving away, the frequency is lower by the Doppler frequency.

Therefore, the frequency of the received signal returned from the spread spectrum state to the original state in the spread spectrum demodulation section 10 is a frequency shifted by just the Doppler frequency with respect to the frequency of the high frequency signal output from the oscillation section 14. This demodulated signal is sent to the mixer 15. A part of the output of the oscillating unit 14 is input to the mixer 15 as a reference signal, frequency conversion is performed here, and the frequency of the difference between the frequency of the demodulation signal and the frequency of the reference signal, that is, the signal of the Doppler frequency is output. To be done. That is, the mixer 15 is the Doppler frequency detecting section in the structure.

The Doppler frequency is, as is well known, proportional to velocity. Using this relationship, the speed measuring unit 16 calculates the speed and sends the speed signal to the warning determining unit 17. The warning determination unit 17 issues a warning to the driver when the speed indicated by the speed signal reaches a preset dangerous speed, and calls attention to a left turn, a right turn, or a course change.

The Doppler frequency is also generated when a vehicle or the like which reflects radio waves goes away, but when it goes away, there is no danger of a left turn or a right turn, so no alarm is issued. Whether the Doppler frequency of the output of the mixer 15 is due to the approach or the movement away from the mixer 15 can be easily discriminated by discriminating the phases because the phases of the both differ by 180 degrees.

The spread spectrum modulation section and spread spectrum demodulation section in the present invention, in short, spread the spectrum distribution of the high frequency output of the oscillation section as transmission energy, and are radiated from the antenna to space in the spread spectrum state and reflected from the object. Any means can be used for returning the spectrum of the signal that has returned and received to the state before spreading again, and is not limited to any system configuration of known techniques. In this embodiment, a specific example of a spread spectrum system called a direct spread system is used.

In FIG. 1, a pseudo noise generator 8 obtains a clock signal from a clock oscillator 9 and randomly generates "1" and "0" signals at a certain period and spreads this signal (pseudo noise code). Send to modulator 7. A continuous wave high frequency signal is input to the spread modulator 7 from the oscillating unit 14, and the high frequency signal of the high frequency signal is changed when the pseudo noise code changes from “1” to “0” or from “0” to “1”. It operates to invert the phase by 180 degrees. This is shown in FIG.
(A) is the output waveform of the oscillator 14, and (b) is the pseudo noise code of the output of the pseudo noise generator 8.

In the figure (b), T ₁ , T ₂ , T ₃ and T ₄ are randomly selected time widths, and for example, a set of T _{1 to} T ₄ is periodically repeated. ing. Then, at the time when the waveform of FIG. 7B changes from “1” to “0” and when it changes from “0” to “1”, the waveform of FIG.
The phase is inverted by 0 degree. As a result, a waveform as shown by the solid line in FIG. 7C is obtained, and the frequency spectrum of such a waveform is spread. The waveform of the part shown by the dotted line in the diagram (c) is the same as that in the diagram (a) and is a reference waveform before the phase inversion.

The signal thus spread spectrum modulated passes through the circulator 5 and the antenna selector 4 and is radiated into space from one of the antennas. The emitted radio waves are
If there is a reflecting object within the radiation angle, it is reflected by the reflecting object, returns to the antenna, and is received. The received signal passes through the antenna switch 4 and the circulator 5, and the spread demodulator 11 of the spread spectrum demodulation unit 10 and the time discrimination control circuit 1
2 to the time discrimination control circuit 12, from the received signal itself to T ₁ , T ₂ of the pseudo noise code ((b) of FIG. 3) on the transmission side.
The time width and order of T ₃ and T ₄ are discriminated, and the pseudo noise code, which is the same as in FIG. 3B and is delayed by the propagation delay time until the radio wave reaches the reflecting object and returns, is generated. 1
Generate to 3. Eventually, this pseudo noise code will be synchronized with the received spread spectrum signal.

The pseudo noise code thus obtained is added to the spread demodulator 11, and is received when changing from "1" to "0" or from "0" to "1" as in the case of modulation. Since the phase of the signal is inverted by 180 degrees, the portion whose phase is inverted by 180 degrees by the spread modulator 7 is eventually the spread demodulator 11
Then, since the phase is inverted again by 180 degrees, the signal returns to the original state and becomes a signal similar to the case where the spread spectrum modulation is not performed, and it includes only the attenuation due to the propagation and the Doppler information. Then, the mixer 15 extracts the Doppler frequency.

[0025]

As described above, since the blind spot recognition assisting apparatus of the present invention spread-spectrum-modulates the transmission signal and radiates it from the antenna, the energy of each frequency component becomes small over a wide range of the spectrum distribution. There is an advantage that it is possible to prevent the occurrence of electromagnetic interference such as causing a malfunction of an electronic device such as another vehicle that receives the radiation of a radio wave. Further, since the antenna switching unit is provided and the transmission / reception is performed only from the antenna in the designated direction, only one transmission / reception system is required, and the cost is reduced as compared with the conventional case where a transmission / reception system is required for each left and right. Has the advantage that Further, since radio waves are emitted only when a left or right direction is instructed, it is possible to save energy and further reduce the possibility of electromagnetic interference.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a comparison diagram of spectrum distributions of a conventional transmission radio wave and a transmission radio wave subjected to spread spectrum modulation.

FIG. 3 is a waveform explanatory diagram of spread spectrum modulation by the direct spread method.

FIG. 4 is a diagram showing a left rear antenna and a right rear antenna attached to a vehicle and a situation of radio wave radiation from the antennas.

[Explanation of symbols]

 1 Right rear antenna 2 Left rear antenna 3 Direction indicator 4 Antenna switcher 5 Circulator 6 Spread spectrum modulator 7 Spread modulator 8 Pseudo noise generator 9 Clock oscillator 10 Spread spectrum demodulator 11 Spread demodulator 12 Time discrimination Control circuit 13 Pseudo noise generator 14 Oscillating unit 15 Mixer 16 Speed measuring unit 17 Warning judging unit

Claims (1)

[Claims] 1. A left rear antenna mounted on the vehicle body in the left rear blind direction of the vehicle; and a right rear antenna similarly mounted in the right rear blind direction;
A direction indicator that outputs a direction signal indicating left or right by left and right direction operation; a left rear antenna when the direction indicator is turned left, a right rear antenna when the direction is right turned, and a transmission path An antenna switching device for switching the connection; an oscillating unit that outputs a high frequency signal when the turn signal indicates a left turn instruction or a right turn instruction; a spread spectrum modulation unit that spread spectrum modulates the high frequency signal from the oscillating unit; A spread spectrum demodulation unit for demodulating the received signal being transmitted; a circulator for guiding a modulated output signal of the spread spectrum modulation unit to the antenna switching device and for guiding a reception signal from the antenna switching device to the spread spectrum demodulating unit; Doppler frequency detection for receiving the demodulated signal from the spread spectrum demodulation unit and detecting the Doppler frequency of the received wave A speed measuring unit that calculates the speed of the moving body captured by any one of the antennas from the Doppler frequency; and a speed signal from the speed measuring unit that has reached a preset critical speed. A blind spot recognition assisting device, comprising: a warning determination unit that issues a warning when the blind spot is detected.