JPH0319196Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement in a lamp lighting device, for example, a power on/off display device for electronic equipment, etc.

[Conventional technology]

As is well known, in order to turn on and off lamps for electronic equipment, etc., DC power supply and AC power supply are required.
Power drive is in practical use. Furthermore, in the past, many lamps were constructed so that the rated current flowed through the lamp at the same time the power switch was turned on, so that the lamp would turn on instantly when the power switch was turned on.

[Problems to be solved by the invention] In such a lamp lighting device, both DC power drive and AC power drive have their advantages and disadvantages. When driven by DC power, the so-called notching phenomenon, in which cracks occur on the surface of the lamp filament, is more pronounced than when driven by AC power, resulting in a shorter lamp life. The notching phenomenon is a phenomenon in which serrations or step-like irregularities appear on the entire or partial surface of the filament during the lighting process of the lamp, and is said to be caused by the movement of tungsten ions. In the case of DC drive, the tungsten ions move in a fixed direction (electric field in a fixed direction), resulting in a severe notching phenomenon, and the thinning of the filament due to this phenomenon leads to abnormally high temperatures due to increased resistance, which accelerates tungsten evaporation and shortens its service life. This results in a shortening of . Therefore, if you want to extend the lifespan, AC drive is recommended. On the other hand, when it comes to changing the output voltage, DC power supplies have a much simpler circuit configuration. That is,
In the case of a DC power supply, this can be achieved with only a transistor and a circuit element for controlling the control transistor, whereas in the case of an AC power supply, a complicated circuit configuration using SCRs and the like is required. Therefore,
Due to design requirements, if you want to configure the display so that the brightness gradually increases after the power is turned on,
Although DC drive is simple, it has the drawback of shortening the life of the lamp and requiring frequent replacement of the lamp.
The design for increased brightness also arose from the desire to extend lamp life. That is, the resistance of the filament when the filament is turned off is much smaller than the resistance when the filament is turned on, and when the rated voltage is suddenly applied, a very large inrush current flows. This rush current is a cause of shortening the life of the lamp.

[Means to solve the problem]

This invention consists of an AC power source, a power transformer connected to the AC power source via a power switch, a rectifier circuit connected to the output of the power transformer, and a voltage control transistor connected to the output of the rectifier circuit. a DC output voltage circuit including a time constant circuit for gradually increasing the base voltage of the transistor; and a lamp is connected to the DC output voltage increasing circuit;
a switching circuit for selectively connecting one of the outputs of the power transformer; and a switching circuit for connecting the lamp to a DC output voltage when the power switch is operated, and after the DC output voltage reaches a predetermined output voltage; This is a lamp lighting device equipped with a timer circuit for connecting the lamp and the power transformer output.

[Effect]

With the above configuration, this device applies a voltage that gradually increases by DC drive when lighting the lamp.
With a simple configuration in which AC drive is performed after a certain voltage is reached, a lighting operation in which the brightness gradually increases from the time the power is turned on can be performed at low cost, and the life of the lamp can be extended.

〔Example〕

In Figure 1, 1 is a DC power supply, 2 is an AC power supply,
3 is a changeover switch, and 4 is a DC
Or a lamp to which one side of the AC power supply is connected,
When the power supply is switched on, a gradually increasing voltage is applied by the DC power supply, and after the DC voltage reaches a constant voltage, the AC power is applied.

In FIG. 2, 21 is a power switch, 22 is a power transformer, 23 is a rectifier circuit, and 24 is a DC output voltage increasing circuit. The output of the DC output voltage increasing circuit 24 is connected to a changeover switch 25. Further, the output of the power transformer 22 is connected to the changeover switch 25. The changeover switch 25 is
Either an AC voltage (output of the power transformer 25) or a DC voltage (output of the output voltage increase circuit 24) is applied to the display lamp 4, which is a load. Further, 26 is a timer circuit that operates in conjunction with the power switch 21, and any suitable known timer circuit can be employed. The time setting for the timer circuit is as described below.
Set the time when the DC voltage reaches a certain value. 27
This is a relay controlled by the timer circuit 26, and the changeover switch 25 is operated by the relay 26. When the power switch 21 is off, the changeover switch 25 is connected to the DC voltage output,
When the power switch 21 is turned on, the output of the rectifier circuit 23 is applied to the output voltage increase circuit 24, and the output of the transistor 24c gradually increases with a time constant determined by the capacitor 24a and the resistor 24b, and the lamp 4
gradually increases in brightness. On the other hand, when the DC voltage reaches a certain voltage after the time determined by the time constant, the timer circuit operates and the changeover switch 2 is activated.
5 to supply AC voltage to the lamp 4.

[Effect of idea]

According to this invention, the constant brightness for a long period of time is driven by AC voltage.
It is possible to prevent a reduction in the life of the lamp due to the notching phenomenon, and also to prevent a rush current at the start of lighting, thereby further extending the life of the lamp. Furthermore, since the brightness is increased by driving with a DC voltage, the circuit configuration is extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of this invention, and FIG. 2 is a circuit diagram of an embodiment of this invention. 2... AC power supply, 21... Power switch, 22
...Power transformer, 23... Rectifier circuit, 24c...
...Voltage control transistors, 24a, 24b...
Time constant circuit, 24...DC output voltage increase circuit, 4
... Lamp, 25 ... Selector switch, 26 ... Timer circuit.

Claims (1)

[Scope of utility model registration request] an AC power source, a power transformer 22 connected to the AC power source via a power switch 21, and a rectifier circuit 23 connected to the output of the power transformer 22;
A time constant circuit 2 connected to the output of the rectifier circuit 23 and used to gradually increase the voltage control transistor 24c and the base voltage of the transistor 24c.
DC output voltage increasing circuit 24 including 4a and 24b.
, a changeover switch 25 for selectively connecting the lamp 4 to either the DC output voltage increasing circuit 24 or the output of the power transformer 22; and when the power switch 21 is operating, the lamp 4 is connected to the DC output voltage increasing circuit 24. It is characterized by comprising a timer circuit 26 for connecting the lamp 4 and the output of the power transformer 22 by the changeover switch 25 after the DC output voltage increasing circuit 24 reaches a predetermined output voltage. Lamp lighting device.