JP2002014680A - Device for driving sound pressure variable buzzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to adjust the sound pressure of a buzzer without PWM control. SOLUTION: The sound pressure variable buzzer driving device where the sound pressure of the buzzer 1 is varied by adjusting a current flowing through the buzzer 1, is provided with plural pieces of circuits in which resisters R1-R4 and transistors Tr1-Tr4 are connected in series, and also a current adjustment part 10, in which the plural pieces of the circuits each are connected in parallel, is connected with the buzzer 1 in series, and further, a microcomputer 6 is provided with plural ports 6a-6d to be connected with respective transistors Tr1-Tr4 arranged for each of the plural pieces of the circuits, and the on-off of the transistors Tr1-Tr4 is controlled by adjusting output voltages of the individual ports 6a-6d based on the input from a sound pressure adjusting means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable sound pressure buzzer driving apparatus which can change the sound pressure by changing the amount of current supplied to a buzzer.

[0002]

2. Description of the Related Art FIG. 2 is a schematic diagram of a conventional sound pressure variable buzzer driving device. As shown in this figure, in the conventional sound pressure variable buzzer driving device, a transistor 52 as a semiconductor switching element is connected in series to a buzzer 51, and when a user or a dealer adjusts the sound pressure adjusting means 53, Microcomputer (hereinafter,
PWM control unit 54a provided in 54)
The output duty ratio of the buzzer 51 is adjusted, the amount of power to the buzzer 51 is adjusted, and the sound pressure of the buzzer 51 is adjusted.

FIGS. 3A and 3B show output waveforms of the PWM control unit 54a when the sound pressure of the buzzer 51 is set to "high" and when the sound pressure is set to "small". As shown in these figures, when the sound pressure of the buzzer 51 is set to “high”, the duty ratio approaches 50%, and when the sound pressure of the buzzer 51 is set to “low”, the duty ratio is set to 0% ( Or 100
%), And the amount of power supplied to the buzzer is adjusted.

[0004]

However, usually,
Since the microcomputer 54 has only one PWM control unit 54a, if the buzzer sound pressure adjustment is performed by the PWM control, the PWM control unit 54a cannot be used for other resources. PWM to resources
When the control unit 54a is used, the sound pressure cannot be adjusted by the PWM control.

There is also a microcomputer provided with two PWM control units, but the PWM control unit is much more expensive than one microcomputer.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to make it possible to adjust the sound pressure of a buzzer without using PWM control.

[0007]

In order to achieve the above object, according to the present invention, the amount of current flowing through the buzzer (1) is adjusted based on the input from the sound pressure adjusting means (7). Thus, in the sound pressure variable buzzer driving device that changes the sound pressure of the buzzer, a circuit that is directly connected to the buzzer and in which the resistors (R1 to R4) and the semiconductor switching elements (Tr1 to Tr4) are connected in series is provided. A current regulating unit (10) having a plurality of circuits and each of the plurality of circuits connected in parallel; and a plurality of ports (6a to 6d) connected to semiconductor switching elements provided in each of the plurality of circuits. A control unit (6) that adjusts an output voltage of each port based on an input from the sound pressure adjusting unit and controls on / off of the semiconductor switching element.
And having the following.

As described above, the amount of current flowing to the buzzer can be adjusted by adjusting the output voltage of each port based on the input from the sound pressure adjusting means and controlling the on / off of the semiconductor switching element. The sound pressure of the buzzer can be adjusted. Thus, the sound pressure of the buzzer can be adjusted without using the PWM control. As the semiconductor switching element, for example, a bipolar transistor described in claim 3 can be applied.

According to a second aspect of the present invention, a plurality of semiconductor switching elements are combined and turned on simultaneously. In this way, by combining a plurality of semiconductor switching elements and turning them on at the same time, it is possible to adjust the number of sound pressures according to the combination.

[0010] The reference numerals in parentheses of the above means indicate the correspondence with the specific means described in the embodiment described later.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows an overall configuration of a variable sound pressure buzzer driving apparatus to which one embodiment of the present invention is applied. Hereinafter, the variable sound pressure buzzer driving device will be described with reference to FIG.

The variable sound pressure buzzer driving device includes a current adjusting circuit 10. The current adjustment circuit 10 includes a plurality (four in FIG. 1) of circuits in which resistors R1 to R4 and bipolar transistors Tr1 to Tr4 as semiconductor switching elements are connected in series. The configuration is such that they are connected in parallel with each other.

The resistors R1 to R provided in the current adjusting unit 10
4 is set so that the resistance value increases in order, for example. If the resistance R1 is 1 kΩ, the resistance R2 is 2 kΩ.
The resistance is set to increase exponentially, for example, kΩ, the resistance R3 is 4 kΩ, and the resistance R4 is 8 kΩ. These resistors R1 to R4 and transistors Tr1 to T
A current adjusting unit 10 composed of r4 is connected in series to the buzzer 1 so that a predetermined voltage + B is applied to the buzzer 1 and each circuit.

On the other hand, each of the transistors Tr1 to Tr4 provided in each circuit of the current adjustment unit 10
5, each port 6a to 6d provided in the microcomputer 6
It is connected to the. Then, the microcomputer 6 adjusts the output voltage of each of the ports 6a to 6d based on the input from the sound pressure adjusting means 7, and controls on / off of each of the transistors Tr1 to Tr4. That is, the microcomputer 6 determines the ports 6a to 6d to output the base signal (predetermined voltage) according to the input from the sound pressure adjusting means 7, and the transistors connected to the ports 6a to 6d to output the base signal. Tr1
Tr4 is turned on. The sound pressure adjusting means 7 includes a volume, a button, and the like operated by a user or a dealer. The outputs of the ports 6a to 6d corresponding to a desired sound pressure are stored in an EEPROM or the like in advance. A mechanism that allows the dealer to appropriately adjust the sound pressure according to the stored contents is also included.

With such a configuration, when an input from the sound pressure adjusting means 7 is made, the microcomputer 6 controls each port 6.
Since the output voltages of a to 6d are adjusted and the desired transistors Tr1 to Tr4 provided in the current adjustment unit 10 are turned on, the currents according to the resistance values of the resistors R1 to R4 connected to the transistors Tr1 to Tr4. Flows to buzzer 1,
The sound pressure can be changed to a desired level.

As described above, the sound pressure of the buzzer 1 can be adjusted without using the PWM control unit provided in the microcomputer 6 by using the sound pressure adjusting buzzer driving device shown in the present embodiment.

Therefore, for example, when a PWM control unit is used for an ultrasonic transceiver in a corner sonar of a vehicle, the PWM control unit cannot be used for a back sonar or the like. Using the variable sound pressure buzzer driving device makes it possible to adjust the sound pressure of the buzzer in a back sonar or the like without using PWM control.

In the configuration of the present embodiment, each of the transistors Tr1 to Tr4 may be turned on one by one, but a plurality of transistors Tr1 to Tr4 may be arbitrarily combined and turned on at the same time. .

By doing so, each transistor Tr1
When each of the transistors Tr1 to Tr4 is turned on one by one, the sound pressure can be adjusted only by the number of circuits including the transistors Tr1 to Tr4 and the resistors R1 to R4. When they are turned on at the same time in combination, the effect is obtained that the sound pressure can be adjusted by the number of combinations (2 ⁴ -1 ways in this embodiment). In such a case, if the resistance values of the resistors R1 to R4 are increased exponentially as described above, the sound pressure can be adjusted exponentially.

(Other Embodiments) In the above embodiment, a bipolar transistor Tr is used as a semiconductor switching element.
Although 1 to Tr4 are used, other semiconductor switching elements may be used. For example, a MOSFET or the like may be used.

Further, a custom IC may be used to draw current directly to adjust the amount of current flowing to the buzzer.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of a sound pressure adjustment buzzer driving device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an outline of a conventional sound pressure adjusting buzzer driving device.

FIG. 3A is a diagram illustrating a PWM in a case where a sound pressure is increased.
It is a figure which shows the output waveform of a control part, (b) is a figure which shows the output waveform of a PWM control part at the time of reducing a sound pressure.

[Explanation of symbols]

1: Buzzer, 2-5: resistance, 6: microcomputer, 6a-6d
... Port, 7 ... Sound pressure adjustment means, 10 ... Current adjustment unit, Tr
1 to Tr4: transistors, R1 to R4: resistors.

Claims (3)

[Claims] The present invention adjusts the amount of current flowing through a buzzer (1) based on an input from a sound pressure adjusting means (7).
In the sound pressure variable buzzer driving device for changing the sound pressure of the buzzer, the buzzer is directly connected to the buzzer, and a resistor (R1 to R4)
And a semiconductor switching element (Tr1 to Tr4) having a plurality of circuits connected in series, each of the plurality of circuits being connected in parallel, and a current adjusting unit (10) provided in each of the plurality of circuits. Ports (6a to 6a) connected to each of the semiconductor switching elements
6d), comprising: a control unit (6) that adjusts an output voltage of each port based on an input from the sound pressure adjusting unit and controls on / off of the semiconductor switching element. Variable sound pressure buzzer drive. 2. The sound pressure variable buzzer driving device according to claim 1, wherein a plurality of the semiconductor switching elements are combined and turned on at the same time. 3. The variable sound pressure buzzer driving device according to claim 1, wherein the semiconductor switching element is a bipolar transistor.