JPS6327901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-vehicle radio receiver, and an object of the present invention is to make it easy to see received frequencies regardless of day or night.

In a normal car radio receiver, as shown in Figure 1, an incandescent light bulb 11 is used to illuminate the scale plate and operation system of the car radio 10, and the power source for this is an illumination cord separate from the power source for the car radio receiver. 9
It is commonly connected to the instrument panel illumination lamp 5. Therefore, when the light switch 3 is turned on, the incandescent light bulb 11 is turned on together with the vehicle underside lamp 4 and the instrument panel illumination lamp 5.

In this case, the brightness of the lamp 5 and the incandescent bulb 11 can be adjusted continuously by the regulator 6. In the figure, 2 is an ignition switch, 8 is a power cord for a radio receiver, and 12 is a light emitting diode (LED) for frequency display.

By the way, in radio receivers that use LEDs for frequency display, such as electronically tuned radio receivers, even if the same method can be used for the part that uses incandescent light bulbs 11, a different method must be used for frequency display using LEDs. It won't happen. For example, a method of switching the duty factor in two stages using a microcomputer, or a method of switching the duty factor in two stages using a microcomputer, or
A possible method is to perform two-step switching based on the on/off state, but in this case, it is not possible to follow the adjustment of the regulator 6.

The present invention eliminates these drawbacks and will be described below with reference to an embodiment of FIG. Here 1
-6, 8-12 correspond to the same reference numerals in FIG. 13 is a power switch. 7 is LED12
A control circuit that controls the power supplied to the transistors 17, 23, 24, 29, 31, and resistors 14 to
16, 18-21, 25-28, capacitor 2
2 and 30.

Next, the operation of this embodiment will be explained. Now, when the lamp switch 3 is turned on in the circuit 7, the voltage adjusted by the regulator 6 is applied to the lamp 5 and the incandescent bulb 11 to turn them on, and the transistor 17 is turned on by the resistors 14 and 15. Accordingly, current flows through the resistor 21 into the transistor 23 due to the resistors 16 and 18. On the other hand, the current flowing through the transistor 24 is determined by the resistors 25 and 26. Transistor 29 is turned on when current flows from the collector of transistor 24, and current is generated in resistor 28, so transistor 31 is turned on and LED 21 is turned on.

Now, by adjusting the regulator 6 and lowering the voltage applied to the lamp 5, the lamp 5 and the incandescent light bulb 11 will become darker, while the base voltage of the transistor 23 will decrease, and the current in the transistor 29 will decrease, so the resistance 28 terminal voltage drops. As a result, the bias of the transistor 31 becomes shallower, so the current flowing through the transistor 31 decreases, and the LED1
The brightness of 2 decreases.

Also, by operating the regulator 6, the lamp 5
When the voltage applied to increases, lamp 5, incandescent bulb 1
1 becomes brighter, and the brightness of the LED 12 also improves.

When the light switch 3 is turned on, the light 5 and the incandescent light bulb 11 are turned off. At the same time transistor 17
Since the base voltage of the transistor 23 decreases, the transistor 17 is turned off, and conversely, the base voltage applied to the transistor 23 increases due to the resistors 18 and 19. As a result, the transistor 23 is turned off, so that the potential difference between the base and emitter of the transistor 24 increases, and the impedance of the transistor 24 decreases.

Therefore, the base current of transistor 29 increases, transistor 29 turns on and lowers the collector voltage, turning on transistor 31 and maximizing the brightness of LED 12.

As is clear from the above embodiments, according to the present invention
This system allows the voltage supplied to display elements such as LEDs to follow the adjustments made by the regulator, while increasing the brightness of the LEDs when the light switch is off.

Therefore, by turning on and off the light switch
LED brightness can be changed even during the day.
This is advantageous in practical terms because the display can be easily seen, and the brightness of the LED can follow the brightness of an incandescent bulb or lamp.

[Brief explanation of the drawing]

Figure 1 is a wiring diagram of a conventional car radio receiver.
FIG. 2 is a wiring diagram of an in-vehicle radio receiver according to an embodiment of the present invention. 3...Light switch, 6...Adjuster, 7...
control circuit.

Claims (1)

[Claims] 1. A switch that turns on and off the lighting system in the car, an illuminance regulator connected in series to this switch, a display element that displays the received frequency, and when the switch is turned on, the display element lights up and the illuminance is adjusted. An in-vehicle radio receiver comprising: a control circuit that changes the brightness of the display element according to the adjustment of the device, and increases the brightness of the display element when the switch is turned off.