JPH0714600U - DC lighting polarity switching device for fluorescent lamps - Google Patents

Abstract

(57) [Summary] [Purpose] To extend the life of fluorescent lamps that are lit by direct current. [Structure] A fluorescent lamp 1 for direct current lighting is connected from an AC power source through a rectifier circuit 2, and a polarity switching circuit 3 for inverting the polarity of the DC power source of the fluorescent lamp 1 at regular intervals is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a liquid crystal display device as a highly stable illumination device for image processing, a backlight for color filter inspection, standard light for solar cell inspection, or a DC lighting polarity switching device for fluorescent lamps used for indoor illumination.

[0002]

[Prior art]

 Conventionally, direct current lighting fluorescent lamps are used in highly stable lighting devices for image processing and the like because they do not flicker or pulsate. For example, a CCD image sensor can be used as a light source for fixed scanning to obtain a highly accurate image signal, and it is also physiologically preferable to AC lighting because it does not cause flicker or pulsation for indoor lighting. There is.

[0003]

[Problems to be solved by the device]

 However, in the case of direct current lighting of fluorescent lamps, the polarity is constant, so the lighting life is shorter than in AC lighting. This is because the electron emitting material (emitter) applied to the filament is gradually scattered and consumed during lighting, and electron emission becomes impossible. Since the scattering and consumption of the emitter is more severe when the lamp is started than when it is being lit, the longer the number of blinks, the shorter the life of the fluorescent lamp.

An object of the present invention is to solve the above-mentioned drawbacks and to realize a long life of a direct-current fluorescent lamp without flicker or pulsation.

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the first invention, a polarity that reverses the polarity of the direct current power source of this fluorescent lamp at regular intervals by connecting a direct current lighting fluorescent lamp from an alternating current power source through a bridge rectification circuit and other rectification circuits A DC lighting polarity switching device for fluorescent lamps equipped with a switching circuit.

In the second invention, the DC lighting polarity switching device for the fluorescent lamp is provided with a polarity switching circuit that reverses the polarity of the previous use and applies the voltage when the DC power is applied to the fluorescent lamp.

[0007]

[Action]

 In the first aspect, the polarity is switched by the signal for switching the polarity at regular intervals or at regular intervals, so that the scattering and emission of the emitter from only one electrode is eliminated. By alternately and evenly radiating the electrons from both electrodes in this way, the life can be extended.

In the second invention, the function of holding the polarity when the power is cut off is provided, and the polarity is reversed and the discharge is started when the power is next turned on. Extend.

[0009]

【Example】

An embodiment of the first invention will be described with reference to FIG. Reference numeral 1 is a direct current fluorescent lamp, and 2 is a rectifier circuit, which is a bridge rectifier circuit. The rectifier circuit is not limited to this bridge rectifier circuit, and various semiconductor rectifiers and the like can be used depending on the application. Reference numeral 3 is a polarity switching circuit, and the contacts R _x-1 and R _x-2 are configured to change the connection at fixed time intervals or at fixed time intervals. For example, a switching circuit equipped with a rotary power switch, a switch with a timer, or a relay. Etc. are used. 4 is a constant current circuit, which keeps the current after discharge constant.

The contacts R _x-1 and R _x-2 are simultaneously switched in the polarity switching circuit 3 at regular time intervals or at regular time intervals, and by switching the polarity of lighting, the scattering of the emitter and the radiation amount are limited, and the life is long. Can be realized. FIG. 2 is a schematic circuit diagram of the second invention, where 1 is a fluorescent lamp, 2 is a rectifier circuit, and 4 is a constant current circuit, which is the same as the example of the first invention. A polarity switching circuit 5 switches the contacts R _x-1 , R _x-2 , and R _x-3 at the same time when the power is turned on, so that the voltage applied to the fluorescent lamp 1 has a reverse polarity. 6 is a start circuit, which works to start the discharge of the fluorescent lamp 1.

When the power is cut off, if the contact is switched and the function of holding it is provided, the polarity will be inverted and discharge will start when the power is turned on next time, so the polarity will always be inverted when lighting. And long life is realized. 3 and 4 are circuit diagrams showing an example of the second invention, showing a two-lamp system. 1 is a fluorescent lamp, 2 is a rectifier circuit, 4 is a constant current power supply circuit, and 6 is a start circuit. Reference numeral 7 is a polarity holding circuit, which uses a self-holding type relay.

FIG. 4 shows an example of the polarity switching circuit.

[0013]

[Effect of device]

 Since the first and second inventions of the present invention have the above-mentioned configuration, in the fluorescent lamp of the direct current lighting, the polarity is switched for a fixed time or a fixed time or when the power is turned on, so that the electron emission of only one of the electrodes is performed. It has become possible to provide an excellent fluorescent lamp with direct current lighting that prevents the consumption of materials, prolongs the service life, and does not flicker or pulsate.

[Brief description of drawings]

FIG. 1 is an explanatory block diagram of a first device.

FIG. 2 is an explanatory block diagram of a second device.

FIG. 3 is a circuit diagram showing an example of a second device.

FIG. 4 is a polarity switching circuit diagram of the second invention.

[Explanation of symbols]

 1 DC lighting fluorescent lamp 2 Rectifier circuit 3, 5 Polarity switching circuit 4 Constant current circuit

Claims (2)

[Scope of utility model registration request] 1. A polarity switching circuit for connecting a direct current fluorescent lamp from an alternating current power source through a bridge rectifying circuit and other rectifying circuits, and inverting the polarity of the direct current power source of the fluorescent lamp at regular intervals. DC lighting polarity switching device for fluorescent lamps. 2. A DC lighting polarity switching device for a fluorescent lamp, comprising a polarity switching circuit for inverting the polarity of the previous use and applying a voltage when a DC power source is applied to the fluorescent lamp.