JPS58162183A - Color mammoth television - Google Patents

Abstract

PURPOSE:To remove a transformer for filament heating and to save energy by using a fluorescent lamp as the display element of each picture element on a screen, and at the off status of the fluorescent lamp, shunting the non-power supply side of filaments to heat the filaments. CONSTITUTION:When a thyristor 5 is turned on, the non-power supply side of the fluorescent filaments 2a, 2b is shunted by the thyristor 5 and a capacitor C3, so that the fluorescent lamp 2 is not discharged and respective filaments 2a, 2b are heated. When the thyristor 5 is turned off, the fluorescent lamp 2 is immediately turned to discharge status. The brightness of the fluorescent lamp 2 is changed in accordance with pulse width modulating signals corresponding to video signals sent from flip flops 81-8n.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color mammoth television for displaying color images in stadiums and the like, and particularly to a color mammoth television that uses fluorescent lamps as color display pixels.

A giant screen television that uses incandescent light bulbs as picture elements for display images, that is, a mammoth television, has already been developed by the applicant and is being implemented in some baseball stadiums, etc., but since it is a monochrome type, It cannot be displayed in color, and there is a strong desire to convert it into color.

Conventional color mammoth television includes red, blue,
There are systems that use cathode ray tubes (hereinafter referred to as CRTs) that emit light in each color of green, and systems that use incandescent light bulbs colored in red, blue, and green as picture elements.

However, in the former method, a high voltage is required to detect a CRT, and therefore, when a display screen made of a CRT is installed outdoors, the CRT becomes a kind of electrostatic precipitator due to the high voltage, and is charged with electricity. Dust attracts and sticks to the CRT surface, darkening the CRT display screen.During the rainy season, the high voltage applied to the CRT can cause spark discharge and cause malfunctions. The biggest drawback of the CRT system is that the manufacturing cost of the mammoth screen becomes enormous because the color generator that constitutes each picture element of the display screen is made of CRT.

In addition, in the latter method using colored incandescent bulbs, the brightness of the blue colored incandescent bulb is extremely low compared to other types, so it is difficult to obtain the same brightness as other red or green incandescent bulbs. If you try to
At the same time, there was a risk that the blue glass would overheat and be destroyed by rain.

Therefore, in terms of efficiency and cost, it is most preferable to use a fluorescent lamp as the light emitting body constituting the color display picture element. However, the fireflies have problems as listed below.

(a) Dimming is difficult; (b) When dimming, one filament heating transformer is required for each fluorescent lamp (two are required for AC use); (c) when used with DC (d) The initial ignition and (e) Dimming is not smooth and causes hysteresis (f)
) A ballast is required, and the loss of the ballast is large (especially when using a resistance ballast in DC lighting, the loss is large).
It is an object of the present invention to provide a mammoth color television using fluorescent lamps as picture elements, which solves the problems described in a) to (f).

In order to achieve this object, the color mammoth television of the present invention includes a large number of red, blue, and green fluorescent lights arranged in rows and nine columns so as to constitute each pixel of the color mammoth display screen. A high-frequency power source for lighting to which the light lamps are connected through their respective LC resonant circuits, a shunt means connected in parallel to the non-power side of the filament of each of the above-mentioned fluorescent lamps and operating in a nuitting manner, and a pulse corresponding to the video signal. and circuit means for generating a pulse width modulation signal and controlling the switching of the shunt means using the pulse width modulation signal to change the brightness of the fluorescent lamp.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a part of the color mammoth television display device according to the present invention, and although the figure only shows one line of circuitry constituting each picture element of the mammoth display screen, in reality, Each picture element consists of three fluorescent lamps, red, blue, and green. Therefore, one color mammoth display screen consists of tens of thousands of fluorescent lamps arranged in rows and columns. .

In FIG. 1 above, 1. ．． 1. , °-"1 n is a fluorescent lamp lighting circuit corresponding to one line having, for example, a red fluorescent lamp 2 of the three primary colors constituting the color picture elements of the mammoth display screen, and 3 is this fluorescent lamp. 2, the high frequency power source 3 includes a DC power source 3a and a DC power source 3.
The electronic switch 3b is composed of electronic switches 3b and 3c made of transistors etc. connected in parallel to the electronic switch 3b.
, 3c are alternately turned on and off to generate a rectangular wave output signal at the output terminal 4 provided at the connection point between both electronic switches 3b and 30, the frequency of which is 10 to 20 KHz. . Further, the output terminal 3 of the high frequency power supply 2. That is, a resonant circuit consisting of a coil L and a capacitor CI is connected in parallel to both ends of the electronic switch 3C, and this resonant circuit resonates with the rising edge of the rectangular wave signal appearing at the output terminal 4 of the high frequency power supply 3 to generate a high ringing voltage. This linking voltage assists the fluorescent lamp 2 in emitting light.

One end of the filament 2a of the fluorescent lamp 2 is connected to one end of the capacitor C1 of the resonant circuit as described above via the capacitor C2''7, and one end of the other filament 2b is connected to the other end. At the same time, a series circuit of a capacitor C3 and a thyristor 5 is connected in one row between the other ends of the filaments 2a and 2b, that is, on the non-power supply side,
Furthermore, a diode 6 is connected in parallel between the art and cathode of the thyristor 5, and the polarity is opposite to that of the thyristor 5. When the thyristor 5 and the diode 6 are conductive, a current is passed through the filaments 2a and 2b, which generates heat at the cutting edge. It is something to do. Further, the collector of a gate control transistor 7□ is connected to the gate of the thyristor 5 via a resistor R7, and its emitter is grounded.
A flip-flop 8 is connected to the base of the transistor 7I.
．． The output of the flip-flop 8. is connected to the flip-flop 8. A parallel output terminal of the display shift register 9 is connected to the input of the display shift register 9. A video amplifier 10 is connected to the input side of the shift register 9.
and A/D converter 11 are connected in series, and this video amplifier 10. The A/D converter 11 and the shift register 9 control the brightness of the so-called fluorescent lamp 2, which converts the video signal into a pulse width corresponding to the brightness of the video signal by modulating the video signal at a commercial frequency.
0) The pulse width modulation signal is transmitted through the flip-flop 8. It is thus drawn out and supplied to the gate of the thyristor 5.

In addition, in FIG. 1, the fluorescent lamp lighting circuit section 12 is shown as a black box. ...The inside of In is circuit section 1
．． It has a circuit configuration similar to that of circuit section 12.
...High frequency power supply 3 is used as a power source for lighting the fluorescent light inside the inn.
In addition, the circuit sections 12...1n include flip-flops controlled by the parallel outputs of the shift registers 9 in order to control the brightness of each fluorescent lamp, similarly to the circuit section 1. Pulse width modulated signals from 82...8n are supplied through transistors 72...7n. Also, 12 is 30
This is a DC power supply for slight discharge of about 0V, and this power supply voltage is connected to the valley circuit section 1+ + 12 + """I via the high resistance R2.
n fluorescent lamps 2, thereby keeping the fluorescent lamps 2 in a dark, slightly discharged state, and immediately discharging the lamps when the lighting power leaks from the cutting edge. Now you can start.

Next, the operation of the inventive device constructed as described above will be explained.

In the high frequency power supply 3 shown in FIG.
When c is alternately turned on and off at a desired frequency, a rectangular wave output signal having a frequency corresponding to the switching frequency, for example 10 to 20 KHz, appears at the output terminal 4 as shown in FIG. Ten thousand.

The circuit of the coil L and the capacitor CI resonates with the rising edge of the above-mentioned rectangular wave signal, and a high linking voltage as shown in FIG. The cutting edge helps the fluorescent lamp 2 to emit light.

Further, when the fluorescent lamp 2 starts discharging, the coil L and the capacitor C2 resonate in series, and a current similar to a sine wave as shown in FIG. 2(c) flows. The voltage waveforms at both ends of the fluorescent lamp 2 at this time also become approximately as shown in FIG. 2(c).

The above explanation describes the relationship between the output waveform of the high frequency power supply 3, the linking voltage generated in the resonant circuit of C2, and the current and voltage supplied to the fluorescent lamp 2, and the blinking and brightness of the fluorescent lamp 2. The control is by a fluorescent light filament) 2a
This is performed by controlling the SIRISK 5 connected to the non-power supply side of +2b using a pulse width modulation signal corresponding to the video signal.The details will be described below. Now, assuming that thyristor 5 is turned on, fluorescent lamp filaments) 2a, 2b
The non-power side of is shunted by the thyristor 5 and the capacitor C3, so even if the high frequency output of the high frequency power supply 3 is coiled and applied to the fluorescent lamp 2 via the capacitor C2, there is no discharge voltage at both ends of the fluorescent lamp 2. The thyristor 5 does not generate this and instead shunts it to the filaments 2a and 2b.
A current flows through the capacitor C3 and heats each filament 2a, 2b. At this time, the diode 6 allows only the current equivalent to half a cycle of the high frequency of the thyristor 5 to flow through the filaments 2a and 2b.

The current flows through the filament for the other half cycle. Also, when thyristor 50 is on, filament)
Heating only 2 a + 2 b in a predetermined state 1c710,
In order to prevent the fluorescent lamp t from emitting much light, this can be achieved by appropriately selecting the frequency of the high frequency power source, the coil, and the values of the capacitors C1 to C3.

Further, when the thyristor 5 is turned off, the voltage across the fluorescent lamp 2 rises rapidly, and the fluorescent lamp 2 immediately shifts to a discharge state and becomes bright (lit).

That is, when the pulse width modulation signal corresponding to the video signal sent out from the flip-flop 81 has a waveform as shown in FIG. When the transistor OFF is turned on, and the thyristor 5 is controlled to turn on and off in accordance with this OFF and ON state, the voltage across the fluorescent lamp 20 becomes as shown in FIG. 3(b), and this voltage waveform In the section 20, the fluorescent lamp 2 is turned on, and in the section 21, the filaments 2a and 2b of the fluorescent lamp 2 are heated. Therefore, a voltage with such a waveform is applied to both ends of the fluorescent lamp 2.
In this case, the fluorescent lamp 2 is turned on at a brightness that corresponds to the width of the waveform portion 20, that is, a brightness that corresponds to the video signal.

Also, flip-flop 8. Assuming that the pulse width modulation signal corresponding to the transmitted video signal has a waveform as shown in FIG. 5, the thyristor 5 is connected to the transistor 7,
On, contrary to the operation of .

This causes a voltage waveform as shown in FIG. 3(d) to be generated across the fluorescent lamp 2. For this reason, waveform part 2
In 2, the fluorescent lamp 2 is discharged and lit, and in the waveform part 23, the filaments 2a and 2bdE710 are heated. The light lamp 2 is brighter than the case shown in FIG. 3 (bl) (it will be lit).

Therefore, flip-flop 8. The brightness of the fluorescent lamp 2 can be reduced to approximately 0 by modulating the pulse width given by
It is possible to smoothly change the state from ~100%.

Further, the lighting control of the fluorescent lamp as described above is performed by the circuit section 12.・
. . . The same applies to In fluorescent lamps.

In the circuit of the above embodiment, the lighting control of the fluorescent lamps for one color in one row of the mammoth display screen was described. A similar circuit configuration is used even when a large number of fluorescent lamps are arranged in one direction, and each fluorescent lamp is controlled by applying a pulse width modulation voltage that changes depending on the video signal. can be formed.

In the above embodiment, the element that shunts the non-power side of the fluorescent lamp filament is a thyristor, but it may also be a transistor. In addition, the high frequency power supply 3 in Figure 1
Although the power source 3a for lighting the fluorescent lamp is shown with the symbol of a battery, in reality, a rectified commercial power source is used, and if the pulse width modulation frequency of the flip-flop 8° is the commercial frequency, it does not need to be smoothed. good.

As described above, according to the present invention, a fluorescent lamp can be used in the display element constituting each pixel of a mammoth display screen, and when the fluorescent lamp is turned off, the non-power side of the filament is shunted and the filament This eliminates the need to provide a transformer for heating the filament of each fluorescent lamp.
In addition to improving the luminous efficiency of the fluorescent lamp and reducing ballast loss, it is possible to save energy.In addition, the circuit that shunts the non-power side of the fluorescent lamp filament can be controlled by a pulse width modulation signal that changes with the video signal. Since the brightness of the fluorescent lamp is changed by
In addition, smooth play without hysteresis is possible, and stable television display without variations in brightness and darkness on the display screen is possible. In addition, because the fluorescent lamp is constantly charged with a voltage that maintains it in a dark, slightly discharged state, it has the advantage of ensuring that the fluorescent lamp lights up and provides stable color display.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a part of a color mammoth television display device according to the present invention, and FIGS. 2 and 3 are explanatory waveform diagrams in the above circuit. 1, ~1n... Lighting circuit for fluorescent lamp, 2... Fluorescent lamp, 3... High frequency power supply, 5... Thyristor (shunt means on the non-power side of the filament), 6... Diode ,
7□~7n...Thyristor control transistor, 81
~8n°°・flip-flop, 9°°shift register, 1o…video amplifier, 11° A/D converter 12…DC power supply for slight discharge.

Claims (2)

[Claims] (1) A large number of red, blue, and green fluorescent lights are arranged in rows and columns to form the valley pixels of the color mammoth display screen, and these common fluorescent lights are connected through their respective LC resonant circuits. A high-frequency power source for lighting, a shunt means connected in parallel to the non-power side of the filament of each of the fluorescent lamps for switching operation, and generating a pulse width modulated signal corresponding to the video signal, and generating a pulse width modulated signal corresponding to the video signal. and circuit means for controlling the switching of the shunt means to change the brightness of the fluorescent lamp. (2) A large number of red, blue, and green fluorescent lights are arranged in rows and columns to form each picture on the color mammoth display screen, and these valley fluorescent lights are connected via their respective LC resonance circuits. a high-frequency power source for the above-mentioned fluorescent lamps, a shunt means connected in parallel to the non-power side of the filament of each of the above-mentioned fluorescent lamps and for switching operation, and generating a pulse-width modulated signal corresponding to the video signal; A color mammoth television comprising circuit means for controlling switching such as shunt means to change the brightness of the fluorescent lamps, and a power source for maintaining each of the fluorescent lamps in a dark, slightly discharged state.