JP4493087B2 - In-vehicle alarm device - Google Patents

Description

  The present invention relates to an on-vehicle alarm device, for example, to an on-vehicle alarm device that avoids electric corrosion of a buzzer that is a source of an alarm that is generated when a vehicle moves backward, and that prevents malfunction and saves power. It is.

Large vehicles such as buses and trucks have a narrow view of the surroundings due to the size and structure of the vehicle body, and require considerable care in driving. Accordingly, an in-vehicle alarm device that emits an alarm sound and alerts the surroundings during driving is indispensable.
For example, at intersections, to avoid accidents involving bicycles, motorcycles and other two-wheeled vehicles or pedestrians when making a left turn, an alarm sound is generated, and an alarm sound is also generated to alert the surroundings when reversing. Yes.
Therefore, as an example of such an in-vehicle alarm device, as a warning device at the time of reversing, for example, a buzzer is provided as a taillight provided at the rear of a large vehicle or a means for generating the alarm sound in the vicinity of the taillight. Yes.
JP, 6-262977, A Here, the back buzzer which audibly notifies retreat is arranged with the electrical equipment attached to the taillight for trucks. This buzzer is usually called a piezoelectric buzzer and includes a piezoelectric diaphragm that emits an alarm sound when an alternating voltage is applied.

When the buzzer is shifted to the back gear when the truck moves backward, the buzzer drive circuit mounted on the bracket of the truck tail lamp is turned on, the drive voltage is supplied to the buzzer, and the piezoelectric diaphragm vibrates. An alarm sound is generated, but the piezoelectric diaphragm is exposed, and when the switch for controlling the buzzer is on the ground circuit side instead of the power source side, for example, during the winter, the piezoelectric vibration is caused by snowfall. Leakage current may flow between the plate and the bracket on which the buzzer drive circuit is mounted.
At this time, since the vehicle-mounted power supply is constantly applied to the buzzer drive circuit, a weak current may flow even in a parked state, and the buzzer may malfunction.
If such a situation is repeated, the piezoelectric diaphragm causes electric corrosion, which may become unusable within a short period of time, resulting in wasted power for the vehicle.
The present invention has been proposed in order to solve such a problem, and avoids electric corrosion of a buzzer mounted on a vehicle due to the constant application of power, and prevents malfunction. In addition, an object of the present invention is to provide an in-vehicle alarm device that saves power.

To achieve the above object, according to the present invention, in claim 1, a piezoelectric buzzer which is mounted at a proper position in the vehicle and issues a warning to the surroundings during operation of the vehicle, and a piezoelectric for applying a driving voltage to the piezoelectric buzzer. A buzzer driving circuit is provided, and this piezoelectric buzzer driving circuit is connected to an in-vehicle power source via a switch circuit, and this switch circuit connects the emitter side of the PNP transistor to the + terminal side of the in-vehicle power source, and the PNP transistor the base side of the first diode via a resistor, and connected to the other terminal side of the cut-off switch to ground one terminal side to the vehicle body, said first diode, the other terminal of the blocking switch to have a rectification action in the side, with connecting collector of the PNP transistor to the positive terminal side of the piezoelectric buzzer drive circuit, the piezoelectric buzzer drive circuit - the terminal side, connected via a second diode to the other terminal side of the cut-off switch, the second diode, to have a rectification action to the other terminal side of the isolation switch, the The piezoelectric buzzer issues an alarm when a drive voltage is applied, and is connected to the piezoelectric buzzer drive circuit independently from grounding to the vehicle body. Both the piezoelectric buzzer drive circuit and the switch circuit are connected to the cutoff switch. When off, it is independent from grounding to the vehicle body side, and when the cutoff switch is on, the negative terminal side of the piezoelectric buzzer drive circuit and the base side of the PNP transistor are grounded from the cutoff switch to the vehicle body side A vehicle-mounted alarm device is proposed.
According to a second aspect of the present invention, there is provided an in-vehicle alarm device according to claim 2, wherein the cutoff switch applies an in-vehicle power source to the piezoelectric buzzer driving circuit in conjunction with a shift operation to a back gear.

  It is possible to provide an in-vehicle alarm device that avoids electric corrosion of a buzzer mounted on a vehicle due to a constant power supply state, prevents malfunction, and saves power.

  According to the first aspect, if the cut-off switch on the negative terminal side of the switch circuit connected to the piezoelectric buzzer driving circuit is turned off, a vehicle-mounted power source is not applied to the buzzer driving circuit, and a weak current flows. The buzzer will not malfunction. Further, it is possible to prevent electrolytic corrosion due to a leakage current between the piezoelectric diaphragm and the bracket on which the buzzer driving circuit is mounted.

  Further, when the vehicle is moving backward, the back switch is turned on and the cutoff switch is turned on to the negative terminal side of the switch circuit, so that the piezoelectric buzzer drive circuit is activated and an alarm sound can be generated from the piezoelectric buzzer.

According to the second aspect , when the vehicle is moved backward, the vehicle-mounted power supply is applied to the piezoelectric buzzer driving circuit for the first time by shifting the gear change lever to the back position. Can contribute.

DESCRIPTION OF EMBODIMENTS Hereinafter, an in-vehicle alarm device according to the present invention will be described with reference to the accompanying drawings, taking one embodiment.
1 to 3 show an in-vehicle alarm device 3 provided at the rear of a vehicle body 2 of a vehicle 1 (truck, bus).
This in-vehicle alarm device 3 is mounted in an electrical component box 4 provided on the vehicle body 2 and includes a piezoelectric buzzer drive circuit 5 and a piezoelectric buzzer 7 provided outside the electrical component box 4 via a bracket 6. A voltage having a predetermined frequency is applied to the piezoelectric buzzer 7 to generate an alarm sound. Then, the piezoelectric buzzer drive circuit 5 is connected to an in-vehicle power source via a switch circuit 8, and a cut-off switch 9 (hereinafter referred to as a back lamp switch 9) is connected to the negative terminal side of the switch circuit 8. The lamp switch 9 is grounded to the vehicle body side.

  Here, an example of the piezoelectric buzzer 7 will be schematically described. As shown in FIG. 2, although not shown in detail, for example, a piezoelectric diaphragm is built in the case C, and this piezoelectric diaphragm has piezoelectric vibration on the metal plate surface. It is the structure which stuck the child. The piezoelectric vibrator is configured by forming electrodes on both main surfaces of the piezoelectric ceramic plate.

Although not shown in detail, the piezoelectric buzzer driving circuit 5 forms a parallel resonant circuit by, for example, the capacitance of the piezoelectric buzzer 7 and the coil CL, and outputs an oscillation signal 10 having a predetermined frequency. A signal having a predetermined frequency is supplied to the transistor Tr1, a drive voltage corresponding to the frequency is generated in the coil CL in the parallel resonance circuit, and this drive voltage is applied to the piezoelectric buzzer 7.
That is, although detailed explanation is omitted, the piezoelectric buzzer driving circuit 5 supplies the output signal of a predetermined frequency generated by the oscillation circuit 10 to the base of the transistor Tr1, thereby turning on and off the transistor Tr1. In response to this, an on / off voltage flows through the coil CL in parallel with the piezoelectric buzzer 7 to generate a drive voltage applied to the resonance frequency in the coil CL, and the piezoelectric buzzer 7 is caused to ring by this drive voltage.

Next, the switch circuit 8 has the emitter of the transistor Tr2 connected to the + terminal side of the on-vehicle power supply, and is connected to the negative terminal side via a diode d1 and a resistor r1 on the base side. A resistor r2 is connected to the emitter side and the base side of the transistor Tr2.
The collector side of the transistor Tr2 is connected to the + side of the piezoelectric buzzer driving circuit 5.

Here, the back lamp switch 9 will be described.
The back lamp switch 9 is configured to shift the gear change lever to the back position when the vehicle 1 is moved backward, so that the on-vehicle power source is applied to the piezoelectric buzzer drive circuit 5 by shifting the gear change lever to the back position.

In the on-vehicle alarm device 3 as described above, when the vehicle 1 is moved backward, if the gear change lever is shifted to the back position, the back lamp switch 9 is turned on, and the transistor Tr2 in the switch circuit 8 is turned on. An application circuit communicating from the power source to the piezoelectric buzzer driving circuit 5 is closed, and an alarm sound can be emitted from the piezoelectric buzzer 7.
When the reverse movement is stopped and the bag gear is returned to neutral, the back lamp switch 9 is turned off, the transistor Tr2 in the switch circuit 8 is turned off, and the application circuit from the in-vehicle power supply to the piezoelectric buzzer drive circuit 5 is cut off. The alarm sound from the piezoelectric buzzer 7 stops.

By doing so, since the transistor Tr2 in the switch circuit 8 is in the OFF state, the voltage from the in-vehicle power source is not applied to the piezoelectric buzzer driving circuit 5, and the leak current from the in-vehicle power source does not flow. Absent.
Accordingly, since no current flows through the piezoelectric buzzer drive circuit 5, even if snow accumulates on the piezoelectric diaphragm of the piezoelectric buzzer 7 and short-circuits with the vehicle body, a weak short-circuit current does not flow, and the piezoelectric buzzer 7 can be prevented, and the occurrence of electrolytic corrosion can be avoided, leading to power saving of the on-vehicle power supply.

  As described above, the on-vehicle alarm device according to the present invention has been described as an example of the alarm device at the time of reversing. However, the on-vehicle alarm device is not limited to this, and the alarm device at the time of left turn, and other cases when the cabin is tilted. Of course, it can be applied to an alarm device or the like.

1 is a schematic side view of a vehicle equipped with an in-vehicle alarm device according to the present invention. It is an external view which shows an example of the piezoelectric buzzer used for the vehicle-mounted alarm device shown in FIG. It is a circuit block diagram which shows one embodiment of the vehicle-mounted alarm device concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Car body 3 In-vehicle alarm device 4 Electrical component box 5 Piezoelectric buzzer drive circuit 6 Bracket 7 Piezoelectric buzzer 8 Switch circuit 9 Back lamp switch 10 Oscillation circuit CL Coil d1 Diode r1, r2 Resistance Tr1, Tr2 Transistor

Claims (2)

A piezoelectric buzzer that is mounted at an appropriate position in the vehicle and issues a warning to the surroundings during operation of the vehicle, and a piezoelectric buzzer drive circuit for applying a drive voltage to the piezoelectric buzzer. The piezoelectric buzzer drive circuit is connected via a switch circuit. This switch circuit is connected to the in-vehicle power source, and the switch circuit has an emitter side of the PNP transistor connected to the + terminal side of the in-vehicle power source, and the base side of the PNP transistor is connected to one terminal side via a first diode and resistor. Is connected to the other terminal side of the cutoff switch grounded to the vehicle body side so that the first diode has a rectifying action to the other terminal side of the cutoff switch, and the collector side of the PNP transistor is while connected to the positive terminal side of the piezoelectric buzzer drive circuit, the piezoelectric buzzer drive circuit - the terminal side, the other of the blocking switch via a second diode Connected to the terminal side, the second diode, to have a rectification action to the other terminal side of the isolation switch, the piezoelectric buzzer with issues an alarm when a drive voltage is applied, to the vehicle body The piezoelectric buzzer driving circuit is connected to the piezoelectric buzzer driving circuit independently of the grounding of the vehicle, and both the piezoelectric buzzer driving circuit and the switch circuit are independent of the grounding to the vehicle body side when the cutoff switch is off, and the cutoff switch is on. In this case , the on-vehicle alarm device is configured such that the negative terminal side of the piezoelectric buzzer driving circuit and the base side of the PNP transistor are grounded from the cutoff switch to the vehicle body side. The in-vehicle alarm device according to claim 1, wherein the cutoff switch is configured to apply an in-vehicle power source to the piezoelectric buzzer driving circuit in conjunction with a shift operation to a back gear.

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