JPS58100391A - Method of dimming lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent lamp dimming method, and more particularly to a fluorescent lamp dimming method that is suitable for use in mammoth televisions, saves power, and operates smoothly.

The mammoth television device consists of a planar body made up of a large number of light emitters arranged side by side, and images are displayed by lighting up each of the light emitters corresponding to each pixel on the display screen. In 1987, the company developed a mammoth television system that used incandescent light bulbs as light emitters to be installed at baseball stadiums and other locations.
It has been filed as No. 42798.

On the other hand, since the above-mentioned mammoth television apparatus using the above-mentioned incandescent lamp system displays images in black and white, there is a strong demand for color display. Therefore, a mammoth television device has been proposed in which incandescent light bulbs are colored blue, red, and green, and these three colored incandescent light bulbs are used as one unit of pixel.However, the blue component in the incandescent light bulb The problem is that the blue light is weak because of the small amount of light produced, and an extremely large amount of power is required overall.

To solve this problem, a mammoth television system has been proposed that uses a small, non-deflecting color cathode ray tube as a light emitting element.

However, devices using color cathode ray tubes have high luminous efficiency and are easy to dim, but because they use high voltage, dust will adhere to the surface of the cathode ray tube when installed outdoors, and moisture will damage the high voltage circuit. A discharge occurs.

Another problem is that the peripheral circuit of the plumber tube becomes complicated and expensive.

As a solution to this problem, a mammoth television apparatus has been proposed in which a warning light, which is much cheaper than a cathode ray tube, is used as a light emitter.

FIG. 1 is a circuit diagram showing an example of a mammoth television apparatus using the above conventional warning light.

In the same figure, 11-1! Reference numeral 1 is a warning light with a large number of light emitting elements arranged in parallel.In order to smoothly turn on and dim light, this warning light 1. ~1, -blade side filament 21~2! 1 is constantly heated by a filament heating power source 3.

In addition, the other filaments 41 to 4n do not need to be heated, but are connected to a power source 6 of about 300V through high resistances 51 to 5n of about IMΩ, respectively, to connect a slight discharge, but this slight discharge is almost This is to the extent that it is impossible to recognize that the light is on. On the other hand, the video signal for image display is
It is converted into a pulse width signal with a frequency of 50 to 60 - and is supplied to the bases of transistors 71 to 71 for lighting each fluorescent lamp.According to this pulse width signal, a current is applied from the main power supply 1° to the filaments 21 to 2n and the warning light. Light 11~1. .

Flows in the order of filaments 41 to 4r, diodes 91 to 1, stabilizing resistors 81 to 8n, and transistors 71 to 7n,
Each of the warning lights 11 to 1n lights up at a brightness corresponding to the video signal. Reference numerals 111 to 11!1 are flip-flop type memories provided for each pixel, which receive and store signals supplied from the shift register 12, and store the signals through the respective transistors 71 to 7.1. as a video signal. In other words, it functions to convert dynamically supplied pixel signals into serial signals.

In addition, in 91 to , the high voltage for slight discharge is connected to the transistor 71.
This is a blocking diode to prevent it from being applied to the ~7n side.

However, in the mammoth television device with the above configuration, as the width of the dimming pulse applied to the dimming transistors 71 to 7 is increased, the brightness initially becomes proportional to the duty of the pulse. However, if you lower the duty from the maximum brightness as shown in Figure 2, you will return home via a path that is brighter than before. Furthermore, if the pulse width is suddenly widened from a narrow point, the operating point will pass through C and shift to a brighter side after a certain time, and the brightness will suddenly become brighter accordingly. In other words, the brightness cannot be smoothly changed in proportion to the pulse width. The cause of such instability is due to the filament heating voltage. In other words, at low duty areas, the filament is heated almost uniformly by the filament heating voltage V, as shown in Figure 3. , the discharge path is formed almost uniformly over the entire surface of the filament. Therefore, the tube voltage is the power supply voltage +
-Vf. However, when the duty increases and the tube current flows, ion bombardment concentrates on one side of the filament, a hot spot appears on one side of the filament, and the discharge path becomes concentrated on one side A of the filament, as shown in Figure 4. In this state, the discharge voltage is equal to the power supply voltage of 10 V.
It is considered that f.

Furthermore, as the filament voltage increases, local discharges also occur between the hot spot on one side of the filament and the + side of the filament. If the filament is heated using a power source with low internal resistance, without a stabilizing resistor, this local current will increase indefinitely, which will not only make the discharge unstable but also have an extremely negative effect on its life. This can lead to increased power loss and a dangerous situation. In other words, when heating a filament to dim a warning light, there are three discharge states shown in Figures 3, 4, and 5, and as a result of these transitions, it becomes unstable and becomes smooth. The light can be adjusted and displayed.

Therefore, an object of the present invention has been made to solve the above-mentioned problems, and a method for controlling the light of a warning light according to the present invention will be explained in detail below with reference to the drawings.

FIG. 6 is a circuit diagram showing an embodiment of the method for controlling the light of a warning light according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols. The difference between this figure and FIG. 1 is that a filament current switching transistor 13 is provided in series with the filament heating power supply 3, and the output of the memory 11 that generates the input signal of the dimming transistor 7 is inverted. The filament switching transistor 13 is configured to be operated by the output of the stone inverter 14.

In a circuit configured in this way, instead of constantly heating the filament as in the case shown in Figure 1,
When the main current flows, the filament is turned off, and the filament current only flows when the main current does not flow. In this case, the main current is a pulse current of 50 to 60 Hz, and its duty changes from 0 to 100% to change the brightness, so the filament current is maximum at the darkest time, and the filament current is at its maximum at the brightest time. becomes zero. If the voltage circuit applied to the tube in this case is schematically shown in FIG. 7, it is equivalent to switching the switch D between Σ and F according to the duty and the voltage K, When D is on, current flows only through the filament, and when D and F are on, only tube current flows.

In this way, in the above configuration, the filament heating current is off while the tube current is flowing, so the equivalent tube voltage is equal to the power supply voltage +- as shown in Figure 3.
The case of 1 Vf does not occur, and there is only one type of state where the power supply voltage to the tube is 10 Vf. Furthermore, as shown in FIG. 5, local discharges induced by the main current do not occur between the filament terminals. In addition, in the above circuit, the filament heating power increases as the discharge current increases, and when the discharge current increases, the filament heating power disappears, but at this time, the filament has hot spots due to the impact of ions generated by the discharge. Since this occurs, the discharge is maintained and there is no need for the filament to waste power, thereby saving power. Furthermore, since there is always one type of equivalent discharge voltage, hysteresis and instability do not occur in the current duty and brightness curves. FIG. 8 shows the duty in the circuit according to this invention.
This is a brightness curve.

In the above-mentioned embodiment, although the description 9 is only shown for the case where light adjustment is performed by pulse width modulation, it goes without saying that the same applies to the case where flow angle control is performed.

In addition to the advantages described above, the fluorescent lamp dimming method according to the present invention is configured so that heating current is passed through the filament only during periods when no discharge current flows.Ninthly, stable brightness adjustment is possible. It is easy to perform and has an excellent effect of preventing wasteful power consumption.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of a conventional fluorescent lamp dimming method.
2 is a brightness characteristic diagram of FIG. 1, FIGS. 3 to 5 are equivalent circuit diagrams of FIG. 1, and FIG. 6 is a circuit diagram showing an embodiment of the fluorescent lamp dimming method according to the present invention. , FIG. 7 is an equivalent diagram of FIG. 6, and FIG. 8 is a luminance characteristic diagram of FIG. 6. DESCRIPTION OF SYMBOLS 1... Fluorescent lamp, 2... Filament, 3... Power source for heating filament, 4... Filament, 5...
Resistor, 6... Power supply, 7... Transistor, 8...
Resistor, 9...Diode, 10...Power supply, 11...
-Memory, 12...shift register, 13...filament switching transistor. Spear 1! ll
Spear. I. Sai 611 tstm off figure spear-8 figure. 1 Nee 74 7 Procedural Amendment (Voluntary) April 7, 1988 Director General of the Patent Office Shima 1) Haruki, Examiner of the Patent Office 1, Indication of the Case 1981 Patent Application No. 1 Ridori 1rf 2, Invention Name: Fluorescent lamp dimming method 3; Relationship with the person making the amendment; Patent applicant: Fuji Electric Co., Ltd.; 4; Agent: 5; Date of amendment order: Showa month, day, day (voluntary); 7; Contents of the amendment (1) ) Amend the claims of the specification as in the attached sheet. (2) On page 1, line 12 of the specification, the word "preferable" is amended to read "suitable." (3) On the 4th line from the bottom of page 3, replace the phrase “I will connect, but” with “
Although it lasts,” he corrected himself. 8. Attached documents (1) Document stating the entirety of the amended scope of claims
Document 2 stating the full text of the claims after amendment (1) Claims In a fluorescent lamp dimming method for dimming a fluorescent lamp by pulse width modulation or flow angle control, the filament u of a fluorescent lamp 1. A method for dimming a fluorescent lamp, characterized by controlling the heating current to flow only during periods when no current is flowing.

Claims (1)

[Claims] In a fluorescent lamp dimming method that uses pulse width modulation or flow angle control to dim the fluorescent lamp, heating current is controlled to flow only during periods when no counter current flows through the filament of the fluorescent lamp. A distinctive feature of the fluorescent lamp dimming method.