JPS60197449A - Antitheft device for car - Google Patents

Abstract

PURPOSE:To prevent theft of such as tire by functioning an alarm means upon detection of the inclination of car over specific angle. CONSTITUTION:An antitheft device is provided with a detector 4 for detecting the inclination of car and mounted on a printedboard 3 arranged in a case 1. Said detector 4 is comprised of first electrode supporting member 41 of circular resin and second electrode supporting member or a metallic cover member 41. Said member 41 has upper face the central portion of which is curved concave while ring electrodes 6a, 6b, 7a, 7b are printed concentrically onto the upper face. Then a metal ball 5 is arranged rollably on said member 41 to detect the inclination angle through variation of electrostatic capacity corresponding with the position of metal ball 5 movable upon inclination of car and to function an alarm means upon exceeding over specific angle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an anti-theft device for a vehicle, and more particularly to an anti-theft device that is effective in preventing theft of tires and the like.

(Prior Art) Conventionally, this type of anti-theft device is known to lock the handles to prevent theft of the vehicle, but it is difficult to prevent theft of tires or theft of the vehicle using a tow truck. It has no effect on

Therefore, anti-theft devices have been proposed that detect and notify changes in the tilt angle caused by lifting the vehicle during theft, but conventional devices require a tilt angle storage circuit or a comparison calculation circuit, etc., and the circuit configuration is The problem was that it was relatively complex.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a vehicle anti-theft device that has a simple circuit configuration and can reliably detect and notify changes in the tilt angle of a vehicle.

[Structure of the invention]

That is, the theft prevention device of the present invention includes a tilt detection means that outputs a tilt signal that periodically changes each time the vehicle tilts by a predetermined angle, and detects that the tilt signal has changed beyond a predetermined value. slope change detection means for emitting a change signal;
and alarm means activated by the slope change signal.

-3- [Example 1] Figures 1 and 2 show a partial cross-sectional view of the present device as viewed from above and from the side, respectively.

The device case 1 is in the shape of a container opening downward, and is mounted on a vehicle with the vertical direction aligned with the state shown in FIG. 2 through holes 11a provided in the flange portions 11 on both sides. A bottom plate 2 covers the opening of the case 1, and a printed circuit board 3 on which a tilt change detection circuit, which will be described later, is formed is disposed inside the case 1.

A circular tilt detector 4 is provided on the printed circuit board 3. The detector 4 includes a first electrode support member 41 made of circular resin.
and a metal cover member 42 which is a second electrode support member and is covered therewith. The electrode support member 41 has a center portion of its upper surface curved downward in a concave shape, while the force spring member 4
2 is thick at the center and has a lower surface convex downward so as to be parallel to the upper surface of the support member 41. In the space formed by the parallel planes, a metal ball 5 is disposed so as to be removable on the electrode support member 41 with a predetermined gap from the lower surface -4- of the cover member 42.

As shown in FIG.
7a and 7b are printed. Each electrode 6a, 6b,
7a and 7b have rod-shaped lead members 61a, 61b, and 71a that penetrate through the support member 41 and reach the printed circuit board 3.
, 71b are connected to each other (FIG. 2), and the lead members 61a, 61t) and the lead members 71a, 71b are connected to each other on the printed circuit board 3 (the third
Figure (dashed line).

Electrode group 6 consisting of the electrodes 6a and 6b and electrode 7a
, 7b and a cover member 42 which also serves as an electrode facing these, there are capacitances CI and C, respectively.
2 occurs. When the vehicle tilts and the metal ball 5 moves, these capacitances C1 and C2 change. That is, when the metal ball 5 is located on the electrode group 6 and is electrically connected thereto, the facing distance between the electrode group 6 and the cover member 42 becomes substantially smaller.
At this time, the capacitance C1 is the maximum, and the capacitance C2 is the minimum -5
− becomes. When the metal ball 5 is located on the electrode group 7, the capacitance C1 becomes the minimum and the capacitance C2 becomes the maximum. Since the electrode groups 6.7 appear alternately no matter which direction the metal ball 5 moves, the capacitance C increases as the metal ball 5 moves.
I and C2 change periodically between maximum and minimum values.

The electrode group 6.7 and the cover part vJ42 are connected on the printed circuit board 3 to a tilt change detection circuit 8 shown in FIG. The slope change detection circuit 8 includes an oscillation circuit 81, a reference signal generation circuit 82, a frequency comparison circuit 83 that compares the frequency t of the oscillation signal 81a and the frequency fO of the reference signal 82a, and when the comparison result changes from the state at the start of parking. A frequency change detection circuit 84 that outputs a change detection signal 84a, and a horn drive circuit 8 that sounds a horn 9 based on the change detection signal 84a.
5 and a constant voltage circuit 86.

The oscillation circuit 81 is an RC (resistance-capacitor) oscillation circuit formed by connecting inverters in series, and the electrode group 6.7 and the cover member 42 are connected to this to form a C (capacitor) component. That is, -6- That is, when the metal ball 5 moves and the capacitances C1 and C2 change periodically, the oscillation frequency f also changes periodically.

The frequency comparison circuit 83 has frequency division counters 831, 832, N
Flip-flop composed of AND gate 833.83
4 and D type flip-flops 835,836. The flip-flops 833 and 834 are the counters 832 and 834.
are set together by a timing pulse 832a synthesized from the output signals of the counters 831 and 831, respectively.
It is reset by output pulses 831a and 831b.

The output states of the flip-flops 833 and 834 are determined by the timing pulse 832b synthesized from the output signal of the counter 832, respectively.
6 is stored.

Frequencies fa and f of the output pulses 831a and 831b
b changes periodically following the oscillation frequency f, and by appropriately selecting the frequency fa1fb and the reference frequency fo, the frequencies fa and fb can be changed based on the frequency fO as shown in FIG. . And, the magnitude relationship between frequency -7- numbers fa and fb and frequency "0" is as shown in A, B in the figure.
As shown in C1D, four states are repeatedly shown depending on the inclination angle of the vehicle, and the flip-flops 835 and 836 are set or reset according to each state. For example, A
In this state, flip 70 knob 835 is reset and flip-flop 836 is set.

The frequency change detection circuit 871 includes flip-flops 841 and 842 that store the output states of the flip-flops 835 and 836 at the time of parking start, and the flip-flop 83.
5.841 and flip 70 tubes 836.842 are different from each other, exclusive OR gates 843.844 generate change detection signals 84a.

Now, when the flashing key switch is turned off when the vehicle is parked, the power supply VB is supplied to the constant voltage circuit 86, and a reset pulse 86a is output when the power supply is turned on.

As a result, the initial alarm prohibition flip 70 knob 87 is set. Subsequently, the counter 832 outputs an initial setting pulse 832C, which resets the flip-flop 70 knob 87 and stores the frequency comparison result at the start of parking in the flip-flops 841 and 842. That is, depending on the movement position of the metal ball 5 (Fig. 2) according to the inclination angle of the vehicle at the start of parking, the flip 70 knob 8711.842 has one of the corresponding states A to 5 in Fig. 5. The frequency comparison result of D is stored.

When the vehicle is stolen, the metal ball 5 rolls and the oscillation frequency f of the oscillation circuit 81 changes.

As a result, the magnitude relationship between the frequencies fa and fb and the frequency 10 changes from one of states A to D in FIG. A signal 84a is emitted. The signal 8
48 activates the relay 851, and the lead wire 1
The horn 9 is blown through the terminal 2.

Furthermore, since the gate 837 is closed by the signal 84a and the timing pulse 8321 is no longer inputted, the output state of the flip-flops 835 and 836 is maintained and the horn 9 continues to blow.

-9- [Embodiment 2] In FIG. 6, a large number of rod-shaped lead members 61a, 61b, 71a, and 71b are embedded in the lower electrode support member 41, and their upper end surfaces meet the upper surface of the support member 41. The electrode is placed in contact with the metal ball 5 for conduction. The lead members 61a, 61b, 71a, and 71b are arranged concentrically as shown in FIG.
a, 71b are shown), the lead members 61a and 61b are connected to each other on the printed circuit board 3 to form an electrode group 6,
The lead members 71a and 71b are connected to each other to form an electrode group 7.

This embodiment also has the same effects as the above embodiment, and since there is no need to print electrodes, the manufacturing cost is low.

In each of the above embodiments, the electrode supporting member is circular in order to detect inclination in all directions, but in the case of detecting inclination in one direction, it can be made into a rectangle along the trajectory of the metal ball. .

-10- Also, in the above embodiment, two electrode groups were provided to form a capacitance that changes complementarily, but it is also possible to use one electrode group to detect the change in capacitance. .

〔Effect of the invention〕

As described above, the vehicle theft prevention device of the present invention is provided with a tilt detection means that outputs a tilt signal that periodically changes each time the vehicle tilts by a predetermined angle, and an alarm is issued when the tilt signal changes beyond a predetermined value. Since the device is configured to emit , there is no need for an inclination angle storage circuit or a comparison calculation circuit, the circuit configuration is extremely simple, and the entire device is compact and inexpensive.

[Brief explanation of the drawing]

Figure 1 is a partial sectional plan view of the device viewed from above, Figure 2 is a partial sectional view taken along the line ■-■ in Figure 1, and Figure 3 is a plan view of the lower electrode support member viewed from above. , FIG. 4 is a circuit diagram of the inclination change detection circuit, and FIG. 5 shows the change in oscillation frequency due to the inclination of the vehicle. FIG. 1, FIG. 6, and FIG. 7 show other embodiments of the present invention. 6 is a partially sectional side view of the device, and FIG. 7 is a plan view of the lower electrode support 11 seen from above. 1... Anti-theft device 4... Tilt detector (tilt detection means) 41.42
... Electrode support member 5 ... Metal ball 6.7 ... Electrode group 6a, 6b, 7a, 7b ... - Electrode 8 ...
...Slope change detection circuit (slope change detection means) 9...
...Horn (alarm means) -12-

Claims (3)

[Claims] (1) A device for preventing vehicle theft caused by vehicle tilting such as tire theft, which includes a tilt detection means that outputs a tilt signal that periodically changes each time the vehicle tilts by a predetermined angle; A vehicle anti-theft device comprising a slope change detection means for detecting that a signal has changed beyond a predetermined value and generating a slope change signal, and an alarm means activated by the slope change signal. (2) The inclination detection means includes a first
and a second electrode support member, which is disposed above the first electrode support member and facing each other at a predetermined interval, and whose lower surface has a convex curved surface parallel to the concave curved surface of the first electrode support member. and electrodes formed on opposing surfaces of first and second electrode supporting members, respectively, and a metal ball removably placed on the opposing surfaces of the first electrode supporting member, one electrode supporting member. The electrode is formed on the entire surface of the opposing surface, and the other =
1 - A plurality of electrodes of the electrode support member are formed at equal intervals in the inclination direction, and the electrodes of the other electrode support member are alternately connected and electrically connected to form two electrode groups, and one electrode support member The vehicle according to claim 1, wherein the capacitance generated between the electrode of the member and each electrode group of the other electrode support member changes periodically as the metal ball moves. Anti-theft device. (3) The concave curved surface and the convex curved surface are respectively formed into a concave spherical surface and a convex spherical surface, and the plurality of electrodes formed on any of the spherical surfaces are arranged concentrically. Anti-theft device for vehicles.