JPH0450188Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement in a display device using a liquid crystal display mounted on a vehicle, particularly in a lighting device that illuminates from behind.

(Prior art) Conventionally, in vehicle display devices using liquid crystal displays, transmissive displays have been widely used that receive illumination light from behind the liquid crystal display to make the display visible day and night. There is. As a light-emitting element used in a lighting device that emits illumination light from behind, a fluorescent lamp described in Japanese Patent Application Laid-Open No. 120077/1977 is often used, and this is a device that is exposed to backlight from the outside. This is due to the fact that a very clear display can be obtained even during the bright daytime.

(Problems to be Solved by the Invention) However, when fluorescent lights are used, it takes time for the fluorescent lights to turn on in cold weather such as early mornings in winter, and the display cannot be seen during this time.
For this reason, a heater or the like has been required to warm the display device, but there is still a problem in that the display cannot be viewed instantly.

(Means for solving the problem) In order to solve the above problem, the present invention adds a tungsten lamp to the lighting device that can be turned on immediately even in cold weather, and when the display device starts, the illumination light from the tungsten lamp is used to display the display. is visually recognized, and the lighting of the tungsten lamp is stopped after the fluorescent lamp is turned on.

(Example) A preferred example of the present invention will be described below based on the drawings.

FIG. 2 is a sectional view showing the structure of the vehicle display device according to the present invention. The transmissive liquid crystal display 2 is electrically connected to a substrate 6 to which electronic components are attached through conductive members 4a and 4b, and enables display by receiving a predetermined display signal. These members are attached to the case 1 along with the color filter 8 and the light scattering plate 10.
It is held within 2. Also, a fluorescent lamp 1 that irradiates illumination light is provided on the case surface 12a behind the liquid crystal display 2.
4a, 14b and tungsten lamps 16a, 16
b are attached, and the fluorescent lamps 14a, 1
4b or tungsten lamp 16a, 16b
The display can be visually recognized by the illumination light.

Figure 1 shows a preferred embodiment (illumination section) of the present invention.
2 is a block circuit diagram, and the driving section of the liquid crystal display 2 is omitted.

The first lighting circuit 18 includes a fluorescent lamp 14, a transistor 20, a booster circuit 22, a one-shot circuit 24, a starter 26, and a current detector 28.
It consists of and. When the first lighting signal is supplied to the base of the transistor 20, the transistor 20 is turned on and the power supply voltage is boosted to the driving voltage by the booster circuit 22, and the driving voltage is applied to the fluorescent lamp 1.
It is applied between the terminals of 4 and 4. When the pulse signal is supplied to the one-shot circuit 24, the starter 26 is activated by a trigger signal generated at the output I, and an initial driving voltage is applied to the fluorescent lamp 14.
When the fluorescent lamp 14 is turned on by the initial drive voltage, the current detector 28 detects the current and outputs a detection signal to the output J. In this embodiment, the lighting state of the fluorescent lamp 14 is detected by the current detector 28.

On the other hand, the second lighting circuit 30 includes a tungsten lamp 16, a transistor 32, and a relay switch 3.
4 and a variable resistor 36. When the second lighting signal is supplied to the base of the transistor 32, the transistor 32 is turned on and current flows from the power source through the tungsten lamp 16, so that the tungsten lamp 16 is turned on. Furthermore, the output C of the lighting switch 38 is connected to the relay coil of the relay switch 34, and the current from the power supply is transmitted to the lighting switch 3.
When 8 is open, the illuminance flows directly to the tungsten lamp 16, resulting in the highest illuminance; when it is closed, the illuminance flows through the variable resistor 36, allowing for dimming or dimming.

The lighting control circuit 40 includes an initial reset circuit 44, an FF 46, and gates 48, 50,
56, OR gate 52, and pulse generator 54
It is composed of and. The output A of the switch 42 linked to the engine key is the initial reset circuit 44.
is supplied to the reset terminal R of the FF 46 through the FF 46, and the FF 46 is reset by the initial reset signal generated at the output B when the switch 42 is closed.

Output A is also provided to AND gates 48 and 50. The AND gate 48 supplies the output E from which the first lighting signal is outputted to the base of the transistor 20, and the inverted output C of the lighting switch 38 is supplied to the other input terminal. On the other hand, the other input terminal of the AND gate 50 has
The output D of FF46 is supplied, and its output F
is supplied to the OR gate 52. The OR gate 52 supplies the output H from which the second lighting signal is output to the base of the transistor 32, and the output C of the lighting switch 38 is supplied to the other input terminal.

Furthermore, the output A is supplied to a pulse generator 54,
When the switch 42 is closed, the pulse generator 54
A pulse signal a with a constant period is generated from . This pulse signal a is supplied to the clock terminal of the FF 46 and the AND gate 56. And FF46
The output J of the current detector 28 is supplied to the D input terminal of the FF 46, and the FF 46 stores the detection signal of the output J in synchronization with the falling edge of the pulse signal a. On the other hand, the AND gate 56 is also supplied with the output D of the FF 46 and the inverted output C of the writing switch 38, and the output G is sent to the one-shot circuit 24.
is supplied to.

The present embodiment is constructed as described above, and its operation will be explained below using the time chart shown in FIG.

When the engine key is turned on at time _t1 , the switch 42 closes, the output A becomes "H", and the initial reset signal generated at the output B causes the FF4 to be turned on.
6 is reset, and the output D is determined to be "H". Therefore, since the output F becomes "H", the output H also becomes "H", and the tungsten lamp 16 is immediately lit by the second lighting signal. Since the lighting switch 38 is normally in the open state, the illuminance of the tungsten lamp 16 is at its maximum here.

On the other hand, since output C is "L", output E is "H"
Therefore, a driving voltage is applied between the terminals of the fluorescent lamp 14 by the first lighting signal. Further, since the AND gate 56 is in an open state, the pulse signal a generated from the pulse generator 54 is outputted to the output G, and the trigger signal is sequentially outputted from the one shot circuit 24 to the output I. Therefore, the starter 26 will sequentially apply an initial drive voltage to the fluorescent lamps 14.

However, when the weather is cold, the fluorescent lamp 14 is not turned on immediately, but is turned on at time _t2 when the fluorescent lamp 14 warms up due to heat generated from the engine and the tungsten lamp 16. It will be lit.

When the fluorescent lamp 14 lights up at time _t2 , a current is detected by the current detector 28, and its output J
A detection signal is output. For this reason, FF46's D
An "H" signal is supplied to the input terminal, and the output D becomes "L" in synchronization with the fall of the pulse signal a, and accordingly, the output F and the output H also become "L". As a result, the supply of the second lighting signal to the second lighting circuit 30 is stopped, and the tungsten lamp 16 is turned off. Further, since the AND gate 56 is closed, the pulse signal a is also no longer output to the output G.

When the lighting switch 38 is closed at time _t3 , such as at night, the output C becomes "H",
Output E becomes "L" and output H becomes "H". As a result, the first lighting circuit 18 is no longer supplied with the first lighting signal, so the fluorescent lamp 14 is turned off, while the second lighting circuit 30 is supplied with the second lighting signal, so the tungsten lamp 16 is turned on. However, at this time, since the lighting switch 38 is in the closed state, the illumination light is attenuated. Furthermore, since the fluorescent lamp 14 is turned off, the current detector 28 no longer detects current, so no detection signal is output to the output J. Therefore, "L" is applied to the D input terminal of FF46.
, the output D becomes "H" in synchronization with the fall of the pulse signal a, and the output F also becomes "H" accordingly.

Then, at time _t4 , when the writing switch 38 is opened again, the output C becomes "L", so the output E becomes "H", and the AND gate 56 becomes open. As a result, the first lighting circuit 18
A first lighting signal is supplied to the fluorescent lamp 14, and a driving voltage is applied between the terminals of the fluorescent lamp 14. Further, since the pulse signal a is output to the output G, a trigger signal is output to the output I, and an initial driving voltage is also applied to the fluorescent lamp 14 by the starter 26. Here, fluorescent light 1
4 is warmed up enough so it lights up immediately.
Similar to the operation at time _t2 , a detection signal is output to the output J, and the output D becomes "L" in synchronization with the fall of the pulse signal a. Therefore, output F and output H
becomes "L", and the AND gate 56 becomes closed. As a result, the supply of the second lighting signal to the second illumination circuit 30 is stopped, so the tungsten lamp 16 is turned off, and the pulse signal a is also no longer output to the output G.

From then on, when the lighting switch 38 is closed, the same operation as at time _t3 is performed, and when the engine key is turned off, the lighting switch 38 is closed.
2 is opened, all operations are stopped.

(Effect of the invention) As described above, according to this embodiment, even in cold weather, the tungsten lamp 16 is immediately turned on when the engine key is turned on, so the display can be visually recognized by this illumination light. be. Moreover, when it is detected that the fluorescent lamp 14 is turned on, the illumination light is
Since the illumination control circuit 40 immediately switches to the illumination light from the fluorescent lamp 14, the conventional clear visibility is not substantially lost. In addition, the fluorescent lamp 1 is heated by the heat generated from the tungsten lamp 16.
4, the fluorescent lamp can be turned on earlier in cold weather without using a heater or the like. Furthermore, in this embodiment, since the tungsten lamp 16 is used to dim the illumination at night, sufficient effects can be obtained with a simple configuration.

As described above, according to the present invention, it is possible to provide a display device for a vehicle that allows the display to be immediately viewed even in cold weather without substantially losing the clear visibility that has been available in the past. can.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a preferred embodiment of the present invention. FIG. 2 is a sectional view of a vehicle display device according to the present invention. FIG. 3 is a time chart showing the operation of FIG. 1. 2...Liquid crystal display, 14...Fluorescent light, 16...
Tungsten lamp, 18...first lighting circuit, 2
8... Current detector, 30... Second lighting circuit, 38
... Lighting switch, 40 ... Lighting control circuit, 42 ... Switch.

Claims (1)

[Scope of utility model registration request] A transmissive liquid crystal display, a fluorescent lamp that emits illumination light from behind the liquid crystal display, and a first lighting circuit that lights the fluorescent lamp in response to a first lighting signal that is output after an engine key is turned on. A vehicular display device comprising: a tungsten lamp that irradiates illumination light from behind the liquid crystal display; and a second lighting circuit that lights the tungsten lamp in response to a second lighting signal output after an engine key is turned on. a lighting detection circuit that detects that the fluorescent lamp is turned on; and a lighting detection circuit that detects that the fluorescent lamp is turned on;
a lighting control circuit that supplies a second lighting signal to the first and second lighting circuits, respectively, and stops supplying the second lighting signal to the second lighting circuit in response to a detection signal from the lighting detection circuit; A vehicle display device characterized by: