JPH0215599A - Device for putting fluorescent lamp on - Google Patents

Abstract

PURPOSE:To make it possible to surely and stably operate a hot cathode fluorescent lamp at all times by starting the operation through cancellation of reduction of light and dimming at the starting operation thereof. CONSTITUTION:In a high frequency inverter circuit 15 for starting, operating and dimming a hot cathode fluorescent lamp 14, a circuit for reducing the light of the lamp 14 by means of a light switch 4 is cancelled (made not to work) for a specified time from the ON operation of an ignition switch 3. At the same time a circuit for dimming the lamp 14 by means of an illumination circuit 5 is cancelled (made not to work) for a specified time. It is thus possible to surely and stably operate the starting illumination of the lamp 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lighting device for a fluorescent lamp, and particularly to a lighting device suitable for a liquid crystal display using a hot cathode fluorescent lamp as a light source for illumination.

[Conventional technology]

Hot cathode fluorescent lamps, which can provide white light with high efficiency, are used as light sources for illuminating liquid crystal displays.

In order to use this hot cathode fluorescent lamp for vehicles, a high frequency inverter type lighting device with a dimming function was developed in Japanese Patent Application Laid-Open No. 1986-
It is described in Japanese Patent Publication No. 49599 and Japanese Patent Application Laid-Open No. 61-494QQ.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not consider, for example, the case where the ignition power supply peculiar to the vehicle is started, the light switch, the illumination control circuit, etc., and the starting and lighting of the hot cathode fluorescent lamp is performed stably. There is no problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluorescent lamp lighting device that can always stably start and light a hot cathode fluorescent lamp used as a light source for illumination.

[Means for solving problems]

The above object is to control a high frequency inverter circuit for starting, lighting and dimming a hot cathode fluorescent lamp and an ignition switch for determining when to start the power supply so that starting and lighting can be performed optimally by a control means.

[Effect]

In the high-frequency inverter circuit that starts, lights up, and dims the hot cathode fluorescent lamp, the light switch cancels (does not operate) the circuit that dims the hot cathode fluorescent lamp for a certain period of time after the ignition switch is turned on. The illumination control circuit also cancels (does not operate) the circuit for dimming the hot cathode fluorescent lamp for a certain period of time to ensure stable starting and lighting of the hot cathode fluorescent lamp.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit configuration block diagram τ showing an embodiment of a fluorescent lamp lighting device for a vehicle instrument panel according to the present invention. In Fig. 1, 1 is a battery power source, 2 is a J5V regulator, 3 is an ignition switch, 4 is a light switch, 5 is an illumination control circuit that generates lighting-related dimming signals, and 6 is an illumination lamp control circuit. This is a Jansell switch during dimming that selects whether to cancel or not cancel dimming or dimming. 7 is a control microcomputer, and a vehicle speed sensor 8.7 detects the vehicle speed as a signal input to the control microcomputer 7.
Engine rotation sensor 9 that detects the engine rotation of the vehicle.
Remaining fuel amount sensor 10 that detects the remaining amount of fuel. There is a signal from a water temperature sensor 11 that detects the water temperature of the radiator.

In response to signals inputted from these sensor groups, the control microcontroller displays various information on the liquid crystal display 12 via a liquid crystal drive circuit 15 that drives the liquid crystal display 12.

The light source for illuminating the liquid crystal display 12 is a hot cathode fluorescent lamp 14, and a high frequency inverter circuit 15 is for starting and lighting the hot cathode fluorescent lamp 14.

The high frequency inverter circuit 15 is a two-stone push-pull system with transistors Q15 and Q10 on the two missing sides of a single oscillation transformer.
By turning these transistors on and off, the hot cathode fluorescent lamp 14 can be dimmed and dimmed. The details are described in JP-A-61-49599 and JP-A-61-49400.1 In a normal high frequency inverter circuit.

Since there is no need to dim or control the brightness of the hot cathode fluorescent lamp 14, the circuit is simpler than the circuit shown in FIG. The high-frequency inverter circuit 15 shown in FIG. 1 satisfies all aspects of ensuring that the hot cathode fluorescent lamp 14 always starts and lights optimally and provides optimal brightness regardless of the operating environment conditions, day and night, or at low temperatures. Contains the functionality you want to use.

-t'', that is, first, the hot cathode fluorescent lamp 14 emits full light (10
In the state (0% brightness), transistors Q13 and Q15 connected to the secondary output of the oscillation transformer are on (Q14
and Q1+5 transistors are turned off). At this time, the lamp current flows to GND via the ballast capacitor C4 and the transistor Q15. Next, in order to reduce the brightness of the hot cathode fluorescent lamp 14 by one step (for example, to 50% brightness), transistor 15 is turned off (transistor pQ16 is turned on), and a lamp current determined by ballast capacitors C4 and 05 is caused to flow. That is, the lamp current flows through the ballast capacitor C4, C5, and the transistor Q15 to GND.

Next, in order to further reduce the brightness of the hot cathode fluorescent lamp 14,
) flowing through the transistor Q15.
Control the flow. In other words, the brightness of the hot cathode fluorescent lamp 14 is further freely and continuously adjusted from 50% to 0 by the signal (duty control) from the illumination control circuit 5, which repeats the ON/OFF operation of the transistor Q15. Let it shine.

In the present invention, the high frequency inverter circuit 15 is connected to the control microcomputer 7, and the hot cathode fluorescent rung 14 is connected to the high frequency inverter circuit 15.
Now performs Jansel during dimming, dimming, and dimming dimming.

The operation will be explained below.

When the evening switch 3 is turned on, the high frequency inverter circuit 15 operates, and the hot cathode fluorescent lamp 14
Lights up at % brightness. Here, if the light switch 4 is turned on, in order to reduce the brightness from 100% brightness of the hot cathode fluorescent lamp 14 to 50%, the control microcombi is operated from the E boat of -, 14' signals are output to turn on the transistor Q16 and turn off the transistor Q15 of the high frequency inverter circuit 15. As a result of this operation, the current that was limited only by the parast capacitor C4 for pump current control is now connected in series with 05.

The lamp current flowing through the hot cathode fluorescent lamp 14 is reduced.

Dim the light. In addition, after the light switch 4 is set to =9 to dim the heat cathode lamp 14, the illumination control circuit (open collector output) 5 is a signal that changes the on/off duty signal to further dim the light. The transistor Q14 of the high frequency inverter circuit 15
, and controls the lamp current of the hot cathode fluorescent lamp 14 by turning on and off the transistor Q13. Here, in order to enable or disable the control of the illumination control circuit 5, the control microcomputer 7 and P
An NP transistor Q7 is inserted between the signal side of the light switch 4 and the illumination control circuit 5 to control the transistor Q14 on the high frequency inverter circuit 15 side. This determination is made based on whether the dimming cancel switch 6 is turned on or off. This is necessary, for example, when a car is driving on a snowy road during the day.
When visibility is poor, the car's headlights are turned on (light switch 4 is turned on) to prevent collisions, and in conjunction with this, the car's display (instrument panel)
This is also the case when canceling the dimming of the light.

(When the surroundings are bright, the display becomes difficult to see when the light is dimmed.) Therefore, if the front dC dimming cancel switch 6 is turned on, even if the light switch 4 is turned on, The hot cathode fluorescent lamp 14 that illuminates the liquid crystal display 12 is connected to the transistor Q14 of the high frequency inverter circuit 15 from the control microcombater so as not to dim or dim the hot cathode fluorescent lamp 14 that illuminates the liquid crystal display 12.
In order not to turn on the transistor Q7, turn off the transistor Q7 (C boat output t-@BJ'), and turn the E boat to °Lour° so as not to turn on the transistor Q16.
Control the output signal so that

As mentioned above, the lighting system used as a vehicle instrument panel must be in its original state (
100 degrees x 64 degrees), and it is necessary to reduce the brightness (50 degrees to 10% brightness) at night. Furthermore, when driving on snowy roads even during the day with the lights on, the instrument panel illumination slows down with the light switches, making it difficult to see the display.

A function is required to turn on the dimming switch 6 and return to the original state without dimming or adjusting the light of the next display.

However, in the high frequency inverter circuit 15 that drives the hot cathode fluorescent lamp 14, the hot cathode fluorescent lamp 1
Dimming 4-? If you want to turn on the engine while it is in the tuning state, [For example, if you want to start the engine with the light switch turned on,
), the hot cathode fluorescent lamp 14 may be half-lit or, in the worst case, cannot be started.

If this is the case, the transistor in the high frequency inverter circuit 15 (
, 115 and 413 are in the off state, the hot cathode fluorescent lamp 14 is not exposed to high-pressure secondary '#1g soil.Therefore, in the present invention, in order to prevent the above-mentioned problems, the hot cathode When starting and lighting the fluorescent lamp 14, control is performed to cancel the dimming and dimming described above and to turn on the fluorescent lamp 14. In other words, in the circuit shown in FIG. 1, when the ignition switch 3 is turned on, the control micro combination,
- The E boat of evening 7 is always held at °L#° for a certain period of time (until the !4 cathode fluorescent rung 14 starts and lights up), the transistor Q16 of the high frequency inverter circuit 15 is turned off, and the transistor Q15 is turned on. do it like this. In addition, the C port of the control microcomputer 7 is also always held at @HL$ for a certain period of time in the same way as above, and the transistor Q7
is turned off, transistor Q14 of the high frequency inverter circuit 15 is turned off, and transistor Q13 is turned on. By performing the control in this way, the hot cathode fluorescent lamp 14 always starts at full brightness with a brightness of 100 cm.
The above-described problem with starting lighting is eliminated, and the hot cathode fluorescent lamp is always lit reliably and stably.

FIG. 2 shows a time chart of each signal section during the start lighting. When the ignition switch turns on, if the light switch is already on and the illumination control circuit's signal is on, the E-boat outputs a warning signal for dimming for a certain period of time. ν”, and the C boat that outputs the output signal for dimming is °HL yl”
I'll leave it as that. As a result, the transistor Q15 that is turned off during dimming is turned on, and the transistor Q15 that is turned off during dimming is also turned on, making it possible to cancel the dimming and drive the high frequency inverter circuit 15.

After canceling the dimming for a certain period of time, the light is returned to the normal dimming state.

The content explained above is that the signal section for dimming and the signal section for dimming are controlled by a microcomputer tough.
It goes without saying that other hard methods may also be used.

Next, FIG. 3 shows a flowchart for carrying out the control described above. That is, in step 20, the ignition switch 3 is determined, and if the ignition switch 3 is on, the process goes to step 21, and the control switch is turned on to start and light the hot cathode fluorescent lamp 14. Output port E of microcomputer 7 is °LkeW”
, the output port C activates the high frequency inverter circuit 15 as "IILpi". In step 22, the light switch 4 is determined, and if the light switch is on, go to step 23, and the t2 source cancel switch 6 is determined, and if the dimming cancel switch 6 is on, the heat Cathode fluorescent lamp 14 is 1 with no dimming)
The lighting state is set to 00chi brightness. If the dimming cancel switch 6 is turned off, the process goes to step 24, and in order to dim and dim the hot cathode fluorescent lamp 140, the output port E of the control microcomputer 7 is switched to °H C9.
The output port C is set to "L, ν" to turn on the transistor Q16 of the high frequency inverter circuit 15 (Q15 is off) and turn on the transistor Q14 (Q15 is off). In step 25, an operating signal for display output to the liquid crystal display 12 shown in FIG.
Output from the port.

If the ignition switch 6 is off in step 20, the process goes to step 26, the high frequency inverter circuit becomes inactive, and the process goes to other processing. Also, step 22
However, if the light switch 4 is off, the hot cathode fluorescent lamp 14 remains in the full state (100% brightness) and outputs the display on the display 12 in step 25. Step 2
3, if the dimming cancel switch 23 is turned on, the hot cathode fluorescent lamp 14 goes to step 25 so that the dimming and dimming is not performed, and the entire light is turned off.

Although the nine embodiments of the present invention described above were used as a lighting device for a vehicle display, it is clear that the invention can be applied to any lighting device that requires dimming and dimming especially during day and night. It is.

Another advantage of the present invention is that the functions of conventional high frequency inverter lighting circuits can be used without any loss.

The starting lighting method described above in the present invention can be solved by changing the number of secondary windings of the missing transformer in the high frequency inverter circuit and increasing the secondary voltage, but the insulation resistance of the missing transformer This is not a good method because new problems arise, such as the breakdown voltage of switching transistors becoming insufficient.

4゜ [Effects of the Invention] According to the present invention, dimming and dimming are canceled when the hot cathode fluorescent lamp is started to be lit, so that the hot cathode fluorescent lamp can always be stably lit. There is an excellent effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration block diagram of an embodiment of the present invention, and FIG.
The figure is a time chart of each signal section at the time of starting lighting of the present invention,
Figure 5 shows the control circuit block diagram shown in Figure 1 when the control microcomputer is used to perform the operations of each part of the control circuit.
-It is a chart. 3...Initial switch, 4...Light switch. 5...Illumination control circuit. 7... Control microcomputer, 14... Hot cathode fluorescent lamp. 15...High frequency inverme circuit. Misfortune (disturbance history revision period darkness) 1-Nuenun 5)

Claims (1)

[Claims] 1. In a fluorescent lamp lighting device comprising a high-frequency inverter circuit that drives a hot cathode fluorescent lamp and a control means that controls dimming and dimming of the hot cathode fluorescent lamp, when the hot cathode fluorescent lamp is started and lit, 1. A fluorescent lamp lighting device comprising means for controlling to start lighting by canceling light and dimming operations.