JPH06249958A - Distance display - Google Patents

Abstract

PURPOSE:To allow high speed processing by combining a pulse wave of predetermined period and a wave reflected on an object to produce a combined pulse wave, converting the combined pulse wave into an analog amount, and determining a distance value. CONSTITUTION:A combined pulse wave generating circuit 3 combines a pulse wave radiated from a radiator 1 and a reflected wave from a receiver 2 to produce a combined pulse wave indicative of the time difference between them. A D/A converter 4 converts the time difference into an analog amount which is presented, as a distance value, on a display 5. The circuit 3 comprises an inverter 31 for logically inverting the pulse wave radiated from the radiator 1, and an AND gate 32 for combining an output pulse from the inverter 31 and the reflected wave from the receiver 2 to produce a combined pulse wave, and the converter 4 converts the pulse width of the combined pulse wave into a voltage to be presented on the display 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance display device, and more particularly to a device for displaying a distance between a front vehicle and a rear vehicle.

[0002]

2. Description of the Related Art Conventionally, as a device for displaying the distance between a vehicle ahead and a vehicle behind, for example, Japanese Patent Laid-Open No. 2-2531
No. 16 or No. 4-215088 is proposed, in which the laser light is emitted from the own vehicle toward the vehicle in front and the laser light is reflected by the vehicle hitting the vehicle in front. Then, the inter-vehicle distance is calculated from the time difference, and the inter-vehicle distance is displayed on the display device,
The alarm device is driven as needed.

[0003]

Since such a distance display device requires a special algorithm or calculation by software, it takes a long time for the whole process and the circuit configuration becomes complicated, resulting in a cost reduction. There was a problem that it would be expensive.

Therefore, an object of the present invention is to realize a distance display device which does not require software calculation.

[0005]

In order to achieve the above object, a device for emitting a pulse wave having a constant period, a device for receiving a reflected wave of the pulse wave from an object to be measured, and the pulse wave. A circuit that synthesizes the reflected wave to generate a pulse composite wave indicating the time difference between the two, a D / A converter that converts the time difference due to the pulse composite wave into an analog amount, and the analog amount is displayed as a distance value. And a device.

[0006]

In the present invention, when a pulse wave having a constant cycle is emitted from the emitting device, the pulse wave is reflected by the preceding vehicle and returns when the preceding vehicle is present. To receive.

Then, in the pulse synthetic wave generating circuit,
The emitted pulse wave and the returning reflected wave are combined to generate and output a pulse combined wave indicating the time difference between the two.

Then, the D / A converter converts the digital time difference indicated by the input pulse composite wave into an analog amount, and the display device displays this analog amount as a distance value.

As described above, in the present invention, since the distance can be displayed by the hardware configuration, it is possible to deal with the processing time and the circuit configuration problem based on the software processing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a hardware configuration diagram of a distance display device according to the present invention, in which 1 is a launching device which emits a pulse wave of a constant cycle, and 2 is a launching device 1. A receiving device 3 that receives a signal in which a pulse wave is reflected from an object to be measured, for example, a vehicle in front, synthesizes a pulse wave from the emitting device 1 and a reflected wave from the receiving device 2 and indicates a time difference between them. A pulse-synthesized wave generating circuit for generating a wave, 4 is a D / A converter for converting the time difference due to the pulse-synthesized wave output from the pulse-synthesized wave generating circuit 3 into an analog quantity, and 5 is output from the D / A converter 4. It is a display device which displays an analog quantity as a value of distance.

The pulse-synthesized wave generation circuit 3 shown in FIG. 1 synthesizes an inverter 31 that logically inverts the pulse wave from the emission device 1, an output pulse of this inverter 31 and a reflected wave from the reception device 2. The D / A converter 4 is a circuit which converts the pulse width of the input pulse composite wave into a voltage and gives it to the display device 5.

The display device 5 is composed of a known circuit that performs peak hold of the input analog amount, and is reset at the falling edge of the input analog amount. In addition, the display uses a numerical value converted into a distance unit according to the analog amount, a bar graph (such as a UV meter in home audio products), or the like.

FIG. 2 is a time chart showing the waveforms of the respective parts in the distance display device shown in FIG. 1. The operation of the embodiment shown in FIG. 1 will be described below with reference to FIG.

First, the pulse wave having a constant cycle emitted from the emission device 1 is directed to the vehicle in front and emitted, and is also sent to the inverter 31 in the pulse composite wave generation circuit 3 to be inverted and sent to the AND gate 32.

When the pulse wave is reflected by the preceding vehicle and returns, the reception device 2 receives the pulse wave and the reflected wave is received as the same pulse wave as the emission wave with a certain time difference as shown in FIG. It is sent to the AND gate 32.

Since the AND gate 32 synthesizes the emitted wave and the reflected wave to generate a pulse synthesized wave as shown in FIG. 2, the D / A converter 4 integrates the pulse synthesized wave to generate the pulse synthesized wave. The voltage waveform corresponding to the pulse width is output.

In this way, the voltage signal obtained by the digital-analog conversion by the D / A converter 4 is
The display device 5 as shown in FIG. 3 displays as a bar graph of the distance corresponding to the voltage signal.

In this case, as shown in FIG. 4, the time until the wave emitted from the vehicle 20 is received as a reflected wave reflected by the vehicle 30 in front is t [seconds], and the inter-vehicle distance is r.
If the distance is [m], the inter-vehicle distance r is calculated by the following equation. r = C × t / 2 [m] (where C represents the speed of light)

Therefore, the inter-vehicle distance r and the integrated value (for example, voltage value) obtained by D / A converting the pulse composite wave by the converter 4
If the display device 5 has a display memory correlated with and, the corresponding accurate distance display can be performed.

FIG. 5 is a system configuration diagram when the distance display device of the present invention shown in FIG. 1 is actually constructed.
In the figure, reference numeral 10 denotes a structure in which the emitting device 1, the receiving device 2, and the pulse-synthesized wave generating circuit 3 are integrated, and by doing so, it is possible to suppress the loss due to the noise of the radio wave signal and the loss in the waveguide. Further, it is more preferable that the D / A converter 4 and the display device 5 are integrated.

FIG. 6 is a diagram showing a state in which the system configuration shown in FIG. 5 is mounted on an actual vehicle. The synthesizing unit 10 shown in FIG. 5 is attached to the bumper portion of the vehicle 20, the converter 4 and The display device 5 is integrated as much as possible and installed near a speedometer (not shown) on the dashboard, which is easily visible to the driver.

If the loss of radio waves in the waveguide can be suppressed, it is not necessary to integrate the transmitting / receiving antenna of the synthesizing unit 10 with the emitting device / receiving device / pulse synthesizing wave generating circuit. For example, as shown in FIG. Alternatively, the antennas 22 may be attached beside the headlights 21, respectively.

[0023]

As described above, according to the distance display device of the present invention, the pulse wave having a constant cycle is combined with the reflected wave which is emitted from the emission device and returned from the object to be measured. Since it is configured to generate a pulse composite wave indicating a time difference, convert the time difference due to this pulse composite wave into an analog amount, and output this analog amount to the display device as a distance value, processing is not performed through software. Since the whole is high-speed and is composed of a simple circuit, there is an advantage that the cost is easier than that of an apparatus involving software processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a distance display device according to the present invention.

FIG. 2 is a timing chart of waveforms of various parts of the distance display device according to the present invention.

FIG. 3 is a diagram showing an embodiment of a display device used in the distance display device according to the present invention.

FIG. 4 is a diagram showing an inter-vehicle distance between a host vehicle and a preceding vehicle.

FIG. 5 is a system diagram when the distance display device according to the present invention is actually configured.

6 is a schematic side view when the system configuration of the present invention shown in FIG. 5 is attached to an actual vehicle.

FIG. 7 is a front view showing an arrangement example when a radar antenna is attached to the side of a headlight.

[Explanation of symbols]

 1 emitting device 2 receiving device 3 pulse synthetic wave generating circuit 4 D / A converter 5 display device In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A device for emitting a pulse wave having a constant period,
A device for receiving a reflected wave of the pulse wave from the object to be measured, a circuit for synthesizing the pulse wave and the reflected wave to generate a pulse combined wave indicating a time difference between the two, and a time difference due to the pulse combined wave A distance display device comprising: a D / A converter for converting the analog amount into an analog amount; and a device for displaying the analog amount as a distance value.