JPH02106899A - Fluorescent lamp lighting device - Google Patents

Abstract

PURPOSE:To enable filament preheating to be always correctly performed at the time of performing starting lighting by providing an oscillation stop circuit stopping oscillation of a high-frequency inverter circuit and a means of controlling preheating of the filament part of a thermocathode fluorescent lamp. CONSTITUTION:A time for temporally turning the transistors Q13 and Q15 OFF is provided in order to temporally open a circuit on the secondary side of a high-frequency inverter circuit 15. For this purpose, an oscillation stop circuit 17 for delaying an oscillation start of a high-frequency inverter circuit 15 until the time, where a microcomputer 7 for control is reset after closing power supply and its operation is stabilized, is provided. That is, the oscillation stop circuit 17 is turned OFF directly after the transistors Q and Q12 turned power supply ON in the circuit on the primary side of the high-frequency inverter circuit 15 until a microcomputer 7 for control normally starts operation. Thereby, when power supply turned on, a thermocathode fluorescent lamp 14 can be lighted after fully performing preheating of a filament 16 of the thermocathode fluorescent 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 is particularly suitable for a lighting device such as a liquid crystal display that uses a hot cathode fluorescent lamp with high luminous efficiency as a light source for illumination. Regarding.

[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-
49399, 1%, and 1982-49400.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a limited lifespan for the number of times the hot cathode fluorescent lamp can be started and turned on, and special consideration has been given to the case when the ignition power is started, the light switch, the illumination control circuit, etc. unique to the vehicle. As there was Zhao while we could not guarantee sufficient reliability.

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a lighting device that can extend the life of a hot cathode fluorescent lamp when starting and lighting the hot cathode fluorescent lamp.

[Means to solve the problem]

In order to achieve the above objectives, starting and
A high-frequency inverter circuit for lighting and dimming, an ignition switch for determining when to start the power supply, and a control means for optimally controlling oscillation of the high-frequency inverter circuit are provided.

[Effect]

In the high-frequency inverter circuit that starts, lights up, and dims hot cathode fluorescent lamps, the hot cathode fluorescent lamp does not turn on immediately for a certain period of time after the ignition switch is turned on.
First, the high-frequency inverter circuit stops oscillating until the control microcomputer is reset and enters the normal operating state, and then the filament of the hot cathode fluorescent lamp is preheated for a certain period of time after the high-frequency inverter circuit starts oscillating. After the filament is sufficiently preheated, the hot cathode fluorescent lamp is turned on from the off state.

By doing this, the hot cathode fluorescent lamp will not turn on even if the ignition is turned on immediately, but will turn on after the filament has been sufficiently preheated, resulting in a longer lifespan. Talented,
Start-up lighting can also be performed reliably and stably.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit configuration block diagram showing an embodiment of a fluorescent lamp lighting device for a vehicle instrument panel according to the present invention. In Figure 1, 1 is for battery weight, 2 is for 5V (Vcc
) 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 a circuit that cancels or cancels dimming or dimming of lighting lamps. There is a dimming cancel switch that allows you to choose whether or not to use it. Reference numeral 7 denotes a control microphone 0 computer, and other signals input to the control microcomputer 7 include a vehicle speed sensor 8 that detects the vehicle speed, an engine rotation sensor 9 that detects the engine rotation of the vehicle, and a fuel level sensor that detects the remaining fuel level. There are signals from a fuel level sensor 10 that detects the remaining amount of fuel, a water temperature sensor 11 that detects the water temperature of the radiator of the vehicle, and the like. In response to the signals input from these sensor groups, the control microcomputer 7
displays each side's information on the liquid crystal display 12 via a liquid crystal drive circuit 13 for driving the liquid crystal display 12.

The marshal for illuminating the liquid crystal display 12 is a hot cathode fluorescent lamp 14, and the 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 type, with transistors Q13 and Q15 on the secondary side of the excavation transformer.
By turning these transistors on and off, the hot cathode fluorescent lamp 14 can be dimmed and dimmed. Details of this are described in JP-A-61-49399 and JP-A-61-49400.

The high frequency inverter circuit 15 shown in FIG. 1 has a circuit configuration particularly considering the case where it is used in a vehicle. The environmental conditions for in-vehicle use include the need to change the illumination brightness of the display between day and night, the lighting lamps to always turn on at the optimum starting point even in low temperature conditions (-30°C), and the need to turn on and off the engine. The number of times the car is turned off is approximately 3 over the lifespan of the car.
This means that the number of flashes of the illumination lamp in the display section is also the same number of times, and it is necessary to withstand this number of times.

The present invention includes functions for satisfying the above-mentioned in-vehicle usage environmental conditions. Next, we will explain them.

In the secondary side circuit of the oscillation transformer of the high frequency inverter circuit 15, first, the hot cathode fluorescent lamp 14 is
% brightness), transistors Q13 and Q15 are turned on (at this time, transistors Q14 and Q16 are turned off). At this time, the lamp current flows through the ballast capacitor C4 and the transistor Q15 to GND.
flows to. Next, light switch 4 is turned on and 14
To bring the hot cathode fluorescent lamp 6 into a dimming state (for example, 50% brightness), turn off the transistor Q15 (at this time turn on the transistor Q16), and reduce the lamp current formed by the ballast capacitors C4 and 05. Flow. That is, the lamp current flows through the ballast capacitor c4, through C5, and through the transistor Q13 to GND.

Next, in order to further reduce the brightness of the hot cathode fluorescent lamp 14, the lamp current flowing through the transistor Q13 is controlled. In other words, the transistor Q13 is turned on.
The repeated OFF operation is performed by the duty control signal from the illumination control circuit 5, and the brightness of the hot cathode fluorescent lamp 14 is further freely and continuously adjusted from 50% to 0%.

At this time, the output port C of the control microcomputer 7 is at Low level, and the transistor Q7 is on.

In the present invention, the high frequency inverter circuit 15 is connected to the control microcomputer 7, and the hot cathode fluorescent lamp 14 is connected to the high frequency inverter circuit 15.
In addition to canceling exposure, dimming, and dimming, it also controls the starting lighting time (filament preheating time) of the hot cathode fluorescent lamp.

The operation will be explained below.

In FIG. 1, when the ignition switch 3 is turned on, the high frequency inverter circuit 15 immediately starts operating, and the hot cathode fluorescent lamp 14 starts lighting at 100% brightness. The problem here is that if the hot cathode fluorescent lamp 14 starts lighting immediately at the same time as the power is turned on, the hot cathode fluorescent lamp 14
A cold start (cold cathode start) occurs without the filament 16 being sufficiently preheated, and the filament 16
It was found that evaporation line disconnection occurs. As a result, the flashing life of the hot cathode fluorescent lamp 14 has become extremely short, and the power supply (ignition switch 3
) On/Off could not be cleared. Therefore, as in the present invention, when the power of the high-frequency inverter circuit 15 is turned on, the filament 16 of the hot cathode fluorescent lamp 14 is first sufficiently preheated, and then the hot cathode fluorescent lamp 14 is turned on. I made it.

For this purpose, the secondary side of the high frequency inverter circuit 15 is
8 It was necessary to temporarily open the circuit, so a time was provided to temporarily turn off transistors Q13 and Q15.

The transistors Q13 and Q15 are controlled by controlling the transistors Q14 and Q16 using the E port and G photo of the control microcomputer 7. Another problem here is that the transistor Q1
4 and Q16 are controlled by the control microcomputer 7. Even when the power is turned on, the control microcomputer 7 does not immediately operate normally, and the
s is required, and during that time the input/output ports of the control microcomputer 7 are in an undefined state. During the reset, the on/off control of the transistors Q14 and Q16 becomes unstable, and as a result, the transistor Q1
3 and Q15 are turned on because current immediately flows through resistors R57 and R60 connected to the ignition power supply line, and the hot cathode fluorescent lamp 14 is turned on without sufficiently preheating the filament 16. In order to solve this problem, the present invention includes an oscillation stop circuit 17 for delaying the start of oscillation of the high frequency inverter circuit 15 until the control microcomputer 7 is reset after power is turned on and the operation is stabilized. Established. That is, the oscillation stop circuit 17 is configured to turn off the transistors Qll and Q12 for a certain period of time immediately after the power is turned on (until the control microcomputer 7 starts operating normally) in the primary side circuit of the high frequency inverter circuit 15. do. for that,
The collector side of Q17 is connected to the power supply line of the ignition switch 3 via a resistor R70, and the base side of Q17 is connected to the power supply line of the 5■ regulator rake 2 via a resistor R6.
8 through a Zener diode ZD1. With this circuit, when the ignition switch 3 is first turned on, before the regulator 2 for 5.
Since the base current of 8 flows through R70 and Ft71, Q18 is immediately turned on (at this time, Q17 is also in the off state). While Q18 is on, the oscillation of the high frequency inverter circuit 15 is stopped. Thereafter, when the potential of the 5V regulator 2 rises and the control microcomputer 7 completes resetting and starts operating normally, the Zener diode ZDI connected to the base side of the transistor Q17 of the oscillation stop circuit 17 Resistor R6
Base current begins to flow through Q8, turning Q17 on. When the transistor Q17 is turned on, the transistor Q18 is turned off, and the high frequency inverter circuit 15, which has been stopped until now, starts to oscillate. When the high frequency inverter circuit 15 begins to oscillate, a preheating current begins to flow through the filament portion 16 of the hot cathode fluorescent lamp 14. At this time, the G port and E photo of the control microcomputer 7 output ``High'' signals to turn on the transistors Q14 and Q16 and turn off the transistors Q1.3 and Q15, respectively. This period is the time for preheating the filament 16 of the hot cathode fluorescent lamp 14. This filament preheating time can be accurately controlled by the control microcomputer 7. Normally, it would be better for the hot cathode fluorescent lamp 14 to turn on immediately when the ignition switch 3 is turned on, for illuminating the light display section, but in order to ensure a long lamp life, Since the longer the filament preheating time is, the longer the life of the hot cathode fluorescent lamp will be, so it is necessary to find the optimal conditions. According to the test results of the present application, if the preheating time is 1 second or more, it is expected that the device can be used as a lamp lighting device with a sufficiently long life. After turning on the ignition, 1
Since it is considered insufficient for the user if the illumination lamp does not turn on for even a second, the preheating time is controlled to within one second. As in the present invention, since this preheating time can be precisely controlled by the control microcomputer 7, it also has the advantage of being able to easily change the control of the time.

After the filament preheating described above, the hot cathode fluorescent lamp 14
In order to light up, the G port and E port of the control microcomputer 7 are set to "LOW", transistors Q14 and Q16 are turned off, and transistors Q13 and Q1 are turned off.
Turn on 5. As a result, the high frequency impark circuit 1
The circuit on the secondary side of 5 goes from an open state to a shorted state, and the hot cathode fluorescent lamp 14 changes from 10 to 12.
The light turns on at full brightness of 0.

FIG. 2 shows a time chart of each signal section at the time of starting the hot cathode fluorescent lamp 14 described above. Since the transistor Q18 of the oscillation delay circuit 17 is on until the ignition switch 3 is turned on from off and the Vcc fji source 5■ rises to a normal potential, the capacitor 033 of the high frequency inverter circuit 15 is shorted. , transistors Qll and Q12 are turned off, and the oscillation of the high frequency inverter circuit 15 is stopped. When the reset period of the control microcomputer 7 is completed and the control microcomputer 7 is started after the Vcc rises by the voltage value, first, the hot cathode fluorescent lamp 1
In order to preheat the filament 16 of No. 4, the G port and E port of the control microcomputer 7 are set to High"
to turn on transistors Q14 and Q16 and turn off transistors Q13 and Q15 in the secondary side circuit of high frequency inverter circuit 15. At this time, in the oscillation delay circuit 17 that had stopped the oscillation, the Vc
Since the signal C has already risen, the transistor Q17 has changed from off to on, the transistor Q18 has changed from on to off, and the high frequency inverter circuit 15 has started oscillating.

After the filament 16 has been preheated for a certain period of time, the G and E ports of the control microcomputer 7 are turned LOW, transistors Q14 and Q16 are turned off, and the transistors on the secondary side of the high frequency inverter circuit 15 are turned off. When Q13 and Q15 are turned on, the hot cathode fluorescent lamp 14, which has been off until now, is turned on.

Here, when the hot cathode fluorescent lamp 14 described in this application is used for a vehicle, it has a configuration that can be used satisfactorily even under the following conditions.

That is, when the car drives with the lights on (light switch 4 is turned on) even during the daytime, such as on a snowy road, the hot cathode fluorescent lamp 14 used for illuminating the display 12 is linked with the light switch 4. If the light is dimmed due to the display, the display part of the display unit 12 may become difficult to see, so turn on the dimming cancel switch 6 and in this case, the display part will not be dimmed or dimmed, but will be completely dimmed. A control signal is sent from the control microcomputer 7 to the high frequency inverter circuit 15 so as to keep the hot cathode fluorescent lamp 14 on in the light (100% brightness) state. That is, the E port output of the control microcomputer 7 is set to "Low", the transistor Q]6 is turned off, and one-step dimming is not performed. Also, in order to cancel the 4N signal from the illumination control circuit 5, the C port output is set to High.
As a result, transistor Q7 is turned off. This turns off the transistor Q14 of the high frequency inverter circuit 15 (Q13 remains on).

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 V
The generation of the high frequency inverter circuit 15 is stopped until the rise of the cc jjjL source.

The control microcomputer 7 starts a reset period and oscillation 15, and the output port G of the control microcomputer 7 is High, and the output port 1-E is High.
As a result, the filament 16 of the hot cathode fluorescent lamp 14 is preheated. Next, in step 23, the output port G of the control microcomputer 7 is set to "LOW"; the output port E is set to "LOW", and the hot cathode fluorescent lamp 14 is turned on. In step 24, the light switch 4 is determined, and if the light switch 4 is on, the process goes to step 25, where the dimming cancel switch 6 is determined, and if the dimming canceling switch 6 is on, the heat When the cathode fluorescent lamp 14 is in its full state (100% brightness), it goes to step 27 and outputs an operation signal from the F port of the control microcomputer 7 to output a display to the liquid crystal display 12.

If the dimming cancel switch 6 is off in step 25, the process goes to step 26, and the hot cathode fluorescent lamp 14 is turned off.
In order to perform dimming and dimming, the output port E of the control microcomputer 7 is set to High, and the output port C is set to "L".
ow” and turns on the transistor Q16 of the high frequency inverter circuit 15 (Q15 is off).16 Also turns on the transistor Q7, and in response to the signal from the illumination control circuit 5, the transistor Q16 of the high frequency inverter circuit 15 turns on. 4 is turned on and off.This causes transistor Q 1 to turn on and off.
3 also turns on and off.

If the ignition switch 3 is off in step 20, the process goes to step 28, where the high frequency inverter circuit 15 becomes inactive and goes to other processing.

As described above in the present invention, when lighting a hot cathode fluorescent lamp, the operation of the high frequency inverter circuit is always operated reliably by the control microcomputer, and the hot cathode fluorescent lamp is started, lit, dimmed, and dimmed. Since it emits light, it is possible to provide a long-life hot cathode fluorescent lamp lighting device. In other words, it can be used as a highly reliable lighting device.

Although the embodiment of the present invention has been described as a lighting device for a vehicle display, it can be similarly applied to any lighting device that requires dimming and dimming especially during day and night. is clear.

〔Effect of the invention〕

According to the present invention, when starting and lighting a hot cathode fluorescent lamp in a high frequency impark lighting device, the filament is always preheated accurately to light the hot cathode fluorescent lamp, thereby extending the life of the hot cathode fluorescent lamp. It has the excellent effect of being able to

[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 section (K section) at the time of starting lighting of the present invention, and FIG. 3 is a flowchart when the control microcomputer performs the operation of each section of the control circuit block diagram shown in FIG. 1. 3... Ignition switch 4 - Light switch 5... Illumination control circuit 7... Control microcomputer 14... Hot cathode fluorescent lamp 15... High frequency inverter circuit 16... Filament 17... Oscillation stop circuit・18 ・

Claims (1)

[Scope of Claims] 1. A fluorescent lamp lighting device comprising a high frequency inverter circuit for driving a hot cathode fluorescent lamp and a control means for controlling dimming and dimming of the hot cathode fluorescent lamp, wherein the high frequency inverter circuit 1. A fluorescent lamp lighting device comprising: an oscillation stop circuit for stopping oscillation of the hot cathode fluorescent lamp; and means for controlling preheating of a filament portion of the hot cathode fluorescent lamp. 2. During the reset period after the control means is powered on,
2. The fluorescent lamp lighting device according to claim 1, wherein oscillation of the high frequency inverter circuit is stopped and oscillation is started after reset. 3. The fluorescent lamp according to claim 1, wherein the secondary side high voltage load section of the high frequency inverter circuit is controlled to be in a conductive state after preheating the filament section of the hot cathode fluorescent lamp. lighting device.