JPS5839239Y2 - display device - Google Patents

Description

[Detailed description of the invention] This invention relates to a display device for displaying information such as the receiving frequency and time of vehicle audio equipment such as car stereos and car radios, and in particular allows the display clarity to be varied in conjunction with the car's dimmer switch. It is.

If the brightness of the display of vehicle audio equipment is made so bright that the display can be clearly read during the day, there is a drawback that it is too bright in dark places such as at night.

Therefore, the object of this invention is to provide a display device that can display images as brightly as possible between the layers and reduce the brightness during dark times at night.

This idea will be explained below.

The dimmer switch is a switch that controls the illuminance of vehicle instrument lighting lamps.Since it is generally used at night, it is connected after the light switch LSO as shown in the circuit diagram in Figure 1, and when the lights are turned on at night, the dimmer switch is switched on. Although the brightness of the meter can be adjusted using the resistor 4, this invention also allows the illuminance of the display device of the car stereo to be adjusted in conjunction with the dimmer switch.

In FIG. 1, the first half of the dotted line is on the car side, and the second half is on the car stereo or car radio side.

In other words, a line that is directly input from the power supply and to which voltage is constantly applied (
Three wires are connected to the car stereo: a battery line), a line input via the ignition key switch (accessory line), and a line input via the dimmer switch (dimmer line).

Regarding the circuit configuration, the coil L and the resistor R1,
A transistor Q+ whose collector is connected to a power source 2 such as a battery and a watch power source TP via a noise filter I consisting of capacitors CI and CI', and this transistor Q1.
The indicator 3 connected to the emitter of Ignition key switch I
S, a voltage divider circuit 5 consisting of resistors R2 and R3 connected via a diode D1 between the base of the transistor Q1 via the ignition key switch IS, and the base of the transistor Q via the dimmer variable resistor 4. A voltage dividing circuit 6 consisting of resistors R4 and R5 connected through a diode D2, a collector connected to the anode of the diode D, and a base connected to the anode of the diode D2 through a voltage dividing circuit 7 consisting of resistors R6 and R7. connected transistor Q
2 will be provided.

Furthermore, as shown in the figure, F is an ILFUSE inserted between the power source 2 and the filter, and D3 is a diode for blocking backflow.

The disconnected capacitors C2 and C3 each function as a filter, and the resistors R8 and R7 function as bias resistors to ensure that the transistors Q1 and Q2 are turned off, respectively.

Further, the dimmer variable resistor 4 can change the illuminance of the car's meter number, and can also be used to change the display illuminance of the car stereo.

In such a configuration, when both the light switch LS and the ignition key switch IS are turned off,
That is, when the vehicle is not in operation and no one is in the vehicle, no voltage is supplied to the base and the transistor Q1 is turned off, so that the voltage of the power supply 2 is not applied to the display 3 and no display is performed on the display 3.

However, power is constantly supplied to the clock counter through the battery line.

When the driver gets in the vehicle and turns on the ignition key switch IS, voltage is supplied to the base of the transistor Q1 via the voltage dividing circuit 5 and the diode D.

Therefore, the transistor Ql is turned on, and the voltage of the power supply 2 is directly applied to the display 3, so that the display is displayed at full brightness.

Next, when driving continues and the light switch LS is turned on at night, the output voltage of the variable resistor 4 (lower than the voltage of the power supply 2) is supplied to the voltage dividing circuit 7 via the voltage dividing circuit 6.
Since the divided voltage is applied to the base of transistor Q2, transistor Q2 is turned on.

Therefore, the output voltage of the voltage divider circuit 5 is grounded and becomes O, and the diode D1 is reverse biased and is separated from the base of the transistor Q1.

-The output voltage of the voltage divider circuit 6 is applied to the base of the transistor Q1 via the diode D2.

Since the transistor Q1 is an emitter follower, the output voltage of the diode D2 and the output voltage of the variable resistor 4 are applied to the display 3.

Therefore, by changing the resistance value of the dimmer variable resistor 4, the voltage applied to the display 3 can be changed.
This changes the display intensity (brightness) of the display 3.

Thus, according to the display device of this invention, in a bright place such as during the daytime, the display can be displayed at full brightness by controlling the accessory line system, and when it is dark at night, the light switch can be turned on and the dimmer switch can be activated via the light switch.
Adjustable display can be achieved by controlling the dimmer line system.

This circuit has a configuration in which the transistor Q+ is used as the main switch and its base is controlled by the accessory wire and dimmer wire system, so all power is supplied to the display through the battery wire system, and the accessory wire and dimmer wire are used for signals. It consumes only a small amount of current.

Therefore, the advantage of a car stereo IE is that if you concentrate noise countermeasures on the battery wire and strengthen it, you can improve the noise prevention on the accessory wire and
This has the effect that the parts of the dimmer wire can be small parts.

[Brief explanation of drawings]

FIG. τ is a circuit diagram showing an embodiment of this invention. G... Filter, 2... Power supply, 3... Display, 4...
...Variable resistor for dimmer, 5~T...Voltage divider circuit, L
S...Light switch.

Claims (1)

[Scope of utility model registration request] A transistor Q1 whose collector is connected to a power supply, an indicator connected to the terminal of the transistor Q, a light switch LS connected between the power supply and the grounded dimmer variable resistor 4, an ignition key switch IS connected to a connection point between the light switch LS and the power source; a voltage dividing circuit 5 connected between the ignition key switch IS and the base of the transistor Q1 via a diode D1; a voltage dividing circuit 6 connected between the conversion resistor 4 and the base of the transistor Q1 via a diode D2; a transistor having a collector connected to the diode D1 and a base connected to the diode D2 via the voltage dividing circuit 7; Q2 and
A display device characterized in that the display brightness of the display device can be varied by the dimmer variable resistor 4.