JPH0130195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a display device that displays an alternating current signal level by the lighting state of a plurality of light emitting diodes.
It is possible to perform accurate display according to the input signal level with a small number of parts.

Conventional configurations and their problems Generally speaking, speaker systems have a problem in that when an excessive input is applied, the boil coil of the speaker burns out and becomes disconnected. However, it is common for ordinary users to have no idea how much input it takes to damage a speaker. Therefore, as shown in Figure 1, four light emitting diodes 2-1 to 2-4 are provided on the front of the speaker box 1, and by lighting up these light emitting diodes in sequence according to the input signal level, it is possible to determine the current level of input. There is a known device that lets you know whether or not it has been added.

As shown in FIG. 2, this display device has light emitting diodes 2-1 to 2-4 connected between input terminals A and B.
and maintenance diodes 3-1 to 3-4 for preventing destruction due to reverse voltage being applied thereto,
It consists of Zener diodes 4-1 and 4-2 connected to resistors 5-1 to 5-4 for preventing excessive input to each light emitting diode and adjusting voltage.

An alternating current speaker drive signal as shown in FIG.
are lit sequentially.

Here, the values of resistors 5-1 and 5-3 are set to 300Ω, the values of resistors 5-2 and 5-4 are set to 800Ω, and the breakdown voltages of Zener diodes 4-1 and 4-2 are set to 12V and 16V, The operation will be explained by taking as an example the case where each of the light emitting diodes 2-1 to 2-4 has a light emission starting current of 10 mA. However, the internal resistance of each light emitting diode 2-1 to 2-4 is assumed to be zero.

To light up light emitting diode 2-1, click here.
It is necessary for a current of 10 mA to flow, and for this purpose, from the relationship E (V) = I (A) × R (Ω), 0.01
A voltage of (A) x 300 (Ω) = 3V needs to be applied between input terminals A and B. Similarly, in order for the light emitting diode 2-2 to light up, it is necessary to apply a voltage of 8V between input terminals A and B. On the other hand, current flows only when a voltage higher than the breakdown voltage is applied to the Zener diodes 4-1 and 4-2, so the light-emitting diodes 2-3 and 2-4 have 12V and 16V between input terminals A and B, respectively. Lights up when voltage is applied.
In other words, in this example, when the input signal is 3V or less, none of the light emitting diodes will light up;
Each time the voltage exceeds 12V or 16V, the light emitting diode 2
1, 2-2, 2-3, and 2-4 will be lit in sequence. Therefore, for example, light emitting diode 2
-1 and 2-2 light up in green to indicate that it is within a safe range, light emitting diode 2-3 light up in yellow to indicate danger, and light emitting diode 2-3 to light up in red to warn. For example, damage to the speaker due to excessive input can be prevented.

However, this configuration requires four diodes, four resistors, and two Zener diodes in addition to the four light emitting diodes, which has the disadvantage of increasing the number of parts and increasing costs.

OBJECTS OF THE INVENTION The present invention provides a display device that can achieve the same functions as conventional devices with a reduced number of parts.

Structure of the Invention The present invention prevents one light emitting diode from applying a reverse voltage to the other light emitting diode by connecting two light emitting diodes in antiparallel. A resistor is connected, and a light emitting diode connected with the opposite polarity to the Zener diode lights up at a voltage higher than the breakdown voltage of the Zener diode, making it possible to display substantially the same display as before. .

DESCRIPTION OF EMBODIMENTS FIG. 4 shows an embodiment of the present invention. In FIG. 4, parts having the same functions as those in FIG. 2 are denoted by the same reference numerals, and explanations thereof will be omitted.

As is clear from Fig. 4, two light emitting diodes 2-1, 2-3 and 2-2, 2-4 are connected in antiparallel, respectively, and a Zener diode 4-1, a resistor 5-1, and a Zener diode 4-1 are connected to each of them. A diode 4-2 and a resistor 5-2 are connected in series.

In this way, when the level of the AC signal applied between input terminals A and B exceeds 3V, it flows from terminal B to terminal A via resistor 5-1, Zener diode 4-1, and light emitting diode 2-1. the current
When the voltage exceeds 10mA, light emitting diode 2-1 lights up. Similarly, when the input signal level exceeds 8V, the light emitting diode 2-2 lights up. When the input signal level exceeds 12V, which is the breakdown voltage of the Zener diode 4-1, the light emitting diode 2-3 lights up, which is the breakdown voltage of the Zener diode 4-2.
When the voltage exceeds 16V, light emitting diodes 2-4 light up. Since one of the light emitting diodes connected in antiparallel to each other prevents a reverse voltage from being applied to the other light emitting diode, the conventional diodes 3-1 to 3-4 can be abolished, and the conventional diodes 3-1 to 3-4 can be abolished. The resistors 5-3 and 5-4 can also be omitted.

Effects of the Invention The present invention connects two sets of anti-parallel connected circuits each consisting of two light emitting diodes between two input terminals to which an AC signal is applied, and connects a Zener diode and a Zener diode in series to these two sets of anti-parallel connected circuits. Connect the series connector with the resistor, and control the lighting of the forward direction light emitting diodes by the Zener diode breakdown voltage value, and control the lighting of the reverse direction light emitting diodes by the resistance value of the resistor, and turn them on sequentially as the input voltage increases. Since the level of the applied AC signal is displayed, the two LEDs can be adjusted to the level of the AC input signal while preventing one LED from applying a reverse voltage to the other LED. The lights can be turned on sequentially depending on the situation.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional speaker system, FIG. 2 is a circuit diagram of its display device, FIG. 3 is an AC input signal waveform diagram, and FIG. 4 is a circuit diagram of an embodiment of the present invention. A, B...input terminal, 2-1 to 2-4...light emitting diode, 4-1, 4-2...zener diode, 5-1, 5-2...resistance.

Claims (1)

[Claims] 1 Between the two input terminals to which the AC signal is applied,
Two sets of anti-parallel connected circuits consisting of two light emitting diodes are connected, and a series connector of a Zener diode and a resistor is connected in series to these two sets of anti-parallel connected circuits, and the lighting of the light emitting diodes in the forward direction is controlled by the Zener diode. A display device that displays the level of the applied alternating current signal by controlling the lighting of the light emitting diodes in the opposite direction by the resistance value of the resistor, and lighting them sequentially as the input voltage increases.