JPS639269Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a high voltage generator used in dry copying machines, electrostatic precipitators, etc.

In recent years, high-voltage generators used in dry copying machines, electric precipitators, etc., have come into use by integrating a high-voltage generation coil and a discharge lamp lighting coil into a flyback transformer, such as one used in television receivers. It has been developed and put into practical use. Here, the high-voltage generation coil is used to cause corona discharge by high-voltage output rectified through a rectifier circuit, and perform charging or dust collection, while the discharge lamp lighting coil is used to generate corona discharge from the coil. This is used when lighting a mercury lamp or an ultraviolet lamp with AC output.

Conventional high voltage generators of this type use transformers that step up commercial frequencies (50 or 60 Hz), or
In the high frequency method that steps up 50KHz,
The generation of high voltage and the lighting of the discharge lamp were performed separately, but both had drawbacks such as the large size and weight, and when using separate power supplies, the beats at different frequencies generated large amounts of noise. was. In addition, in a high-frequency system that uses a single oscillator to generate high voltage and light the discharge lamp, if the high-voltage load fluctuates, the effect will also appear on the discharge lamp side as a voltage change, causing the discharge lamp to flicker. The disadvantage is that normal discharge is not carried out due to such reasons, which causes the discharge lamp to turn black and shorten its life by half.
In particular, since the voltage waveform supplied to the discharge lamp is alternating current,
A disadvantage is that if there is waveform distortion, it may cause noise.

The present invention was devised to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a high voltage generator driven by a single frequency using the same transformer.

An embodiment of the high voltage generator of the present invention will be described in detail below with reference to the drawings. In Fig. 1, reference numeral 1 denotes a two-part core made of a magnetic material such as ferrite.A primary coil 2 and a high voltage generating coil 3 are wound around one leg of the core 1 in an overlapping manner. A discharge lamp lighting coil 4 is wound around the other leg piece.
The whole forms a trance. Among the coils wound around the core 1, the primary coil 2 is
As shown in the figure, the transistor circuit 5 is connected to a bias resistor.
It consists of R ₁ , R ₂ , a feedback capacitor C ₁ , and an oscillation transistor Tr, and forms a self-excited oscillation circuit together with the primary coil 2. On the other hand, as shown in FIG. 2, a high voltage rectifier diode 6 is connected to the output side of the high voltage generating coil 3 which is wound insulated from the primary coil 2.
The discharge lamp lighting coil 4 includes a resonant capacitor C ₂ ,
Current limiting capacitor _C3 is connected. and,
The core 1 is placed over the same leg piece so that the primary coil 2 and the high voltage generating coil 3 are magnetically tightly coupled, and the primary coil 2 and the discharge lamp lighting coil 4 are magnetically loosely coupled. The two legs are respectively arranged on different leg pieces of the core 1.

In the high voltage generator having such a configuration, the oscillation waveform on the primary side is generated by the transistor of the transistor circuit 5.
By operating the Tr at Class C in consideration of its heat loss, it forms a pulse waveform as shown in Figure 3A, and along with this, the secondary side (high voltage generation coil 3, discharge lamp lighting coil The waveform of the coil 4 side) is also
As shown in Figure B, the waveform includes ringing during the on period. In other words, the fundamental waveform contains harmonic components. Here, in order to control the noise generation in the discharge lamp and extend the life of the tube, it is necessary to make the waveform applied to the discharge lamp close to a sine wave with a single frequency. By arranging the discharge lamp lighting coil 4 with loose magnetic coupling, the waveform generated from the discharge lamp lighting coil 4 has a linear level during the on period of the oscillation waveform, as shown in FIG. 3C. The state is close to that of a sine wave. (Since the number of turns of the discharge lamp lighting coil 4 is as small as several hundred turns, there is almost no effect of distributed capacitance.)
At this time, the waveform can be further improved by combining it with the resonant capacitor _C2 connected to the discharge lamp lighting coil 4. On the other hand, the high voltage generation coil 3 is arranged in a state of close magnetic coupling with the primary coil 2, so even if the number of turns is as large as 2000 to 3000 turns, it is not affected by the distributed capacitance, and the input Power is expressed in its complete form as output.

In one embodiment of the high voltage generator of the present invention, a transistor circuit and a primary coil constitute a self-excited oscillation circuit. It's a good thing.

As described above, the high voltage generator of the present invention includes a primary coil 2 connected to a transistor circuit 5, a high voltage generating coil 3 wound insulated from the primary coil, and a discharge lamp lighting coil. 4 in the same transformer, the primary coil 2 and the high voltage generating coil 3 are magnetically tightly coupled, and the primary coil 2 and the discharge lamp lighting coil 4 are magnetically loosely coupled. The high voltage output generated by the high voltage generating coil is not affected by distributed capacitance, so circuit loss is extremely low.
As a result, without causing heat generation in the core or copper wire,
This produces the effect that it can always be obtained efficiently and in a stable state. In addition, the output generated by the discharge lamp lighting coil can be improved in waveform and become close to a sine wave by simply loosening the magnetic coupling between the primary coil and the discharge lamp lighting coil. This has the effect of reducing noise generation, preventing the blackening phenomenon of the discharge lamp, and extending the life of the tube. Furthermore, high voltage generation and discharge lamp lighting are performed by single frequency drive using the same transformer, which also has the effect of preventing the generation of noise due to beats.

[Brief explanation of drawings]

Figure 1 is a cross-sectional side view of the configuration of a high voltage generator according to an embodiment of the present invention, Figure 2 is its circuit configuration diagram, Figure 3A is an oscillation waveform diagram in the high voltage generator, and Figure 3B is its oscillation waveform diagram. The output waveform diagram of the secondary side, FIG. 3C, is the output waveform diagram generated by the discharge lamp lighting coil. 1...Core, 2...Primary coil, 3...High voltage generation coil, 4...Discharge lamp lighting coil, 5...
transistor circuit.

Claims (1)

[Scope of utility model registration request] Primary coil 2 connected to transistor circuit 5
, a high voltage generation coil 3 wound insulated with respect to the primary coil, and a discharge lamp lighting coil 4 are provided in the same transformer, and the primary coil 2 and the high voltage generation coil 3 are magnetically connected. A high voltage generator characterized in that the primary coil 2 and the discharge lamp lighting coil 4 are magnetically loosely coupled.