JPS5939178A - Video display device - Google Patents

Abstract

PURPOSE:To prevent the deterioration in life of a discharge light, by setting an output frequency of an AC power supply device energizing the discharge light to a multiple of a product between a scanning frequency of a video signal and the number of stages of dimmer so as to mitigate the asymmetricity of the lamp current of the discharge light. CONSTITUTION:Discharge lights 11-1n are used as display elements, the discharge lights are energized with AC power supply devices 31-3n, and the output frequency of the AC power supply devices 31-3n is set to an integral multiple of the product between the scanning frequency of the video signal and the number of stages of dimmer. Thus, the AC voltage having an integral number of cycles is applied always to the discharge light 11-1n and the asymmetricity of the lamp current is decreased, allowing to attain the long life of the discharge lights.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video display device in which a large number of light-emitting display elements are arranged on a display panel, and the amount of light emitted by these display elements is controlled to display images such as television signals.

Conventionally, in this type of display device, a light bulb,
1 using a diode ray tube is known. However, light bulbs have a problem in that they consume a lot of power and generate a lot of heat due to their low luminous efficiency, and those using a lumen tube are expensive and difficult to obtain a sufficient amount of light.

On the other hand, devices using fluorescent lamps as display elements have also been proposed.
No. 797). The use of a fluorescent lamp is advantageous over the above-mentioned light bulbs and cathode ray tubes in that it has good luminous efficiency, a relatively low value of ρ, and sufficient light extinction. However, in the cited document, the fluorescent lamp is lit with a curved voltage, so it is necessary to use a resistor in the current limiting device. Therefore, there are problems in that there is a lot of power loss and heat generation in the resistor g2 serving as the current limiting device.

In response to this, the present inventors have proposed an image display device in which the display element includes a discharge lamp and a high frequency generator that energizes the discharge lamp.
No. 9). This device can eliminate the above-mentioned gap in the conventional 5M position, and has good responsiveness to the video signal H, making it extremely effective.

The inventors of the present invention conducted research on discharge lamps that are lit using alternating voltage, such as this one, and discovered the problem of burning. In other words, when performing dimming by controlling the lighting period of a discharge lamp according to a video signal, depending on the selected frequency of the AC voltage, the lamp current of the discharge lamp becomes asymmetric between positive and negative, causing a cataphoresis phenomenon, which can shorten the life of the discharge lamp. It could have a negative impact. For example, when dimming a discharge lamp in 8 steps, at the deepest point, the lamp should be injected into the discharge lamp for half a cycle or one cycle of AC voltage.
If only half a cycle is supplied, the lamp current of the discharge lamp will have a significant asymmetry between positive and negative, and the above problem will become serious.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide an image display device that can alleviate the positive/negative asymmetry of the lamp current of a discharge lamp and prevent deterioration of the life of the discharge lamp.

The present invention uses a discharge lamp as a display element, and the discharge lamp is energized by the output of an AC power supply, and the output frequency of the AC power supply is adjusted to the scanning frequency of the video signal and the number of dimming stages. This feature is set to an integral multiple of the product of .

In the present invention, since the output frequency of the AC power supply device is set as described above, the AC voltage is supplied for at least one cycle at the bottom during the lighting period of the discharge lamp during the deepest dimming, and only half a cycle or one and a half cycles are supplied. Since no alternating current voltage is supplied, the lamp current value can be equalized in positive and negative directions. Therefore, it is possible to prevent the life of the discharge lamp from being shortened due to the cataphoresis phenomenon occurring.

In the present invention C2, the video No. 48 is a continuous electric signal obtained by scanning one image/one point, and is a television signal, video signal, movie signal, etc. Furthermore, the scanning frequency of the video signal represents the number of video images transmitted per second. Furthermore, the number of secondary light stages is, for example, 8.16.32.64
However, in the present invention, C2 in the sub-light stage does not include a light-off level. .

Further, in the present invention C2, both black and white display and color display are possible. In the case of color display, in C2, 62 discharge lamps having red, green, and blue emission colors are arranged adjacent to each other to form one stroke.

Furthermore, C2, the present invention (in C2), a fluorescent lamp, a neon tube, etc. can be used as the discharge lamp.

Further, the AC power supply device can be configured using an inverter. In this case, the inverter may be either self-excited or separately excited.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. (11) to (1n) are discharge lamps, such as fluorescent lamps, which are arranged in large number M (2).

The display panel (2) is attached to a baseball stadium or the like, and the discharge lamps (II) to (1n) are installed in dozens or more. Electric light (II
) to (1n), which in this embodiment have a one-to-62 correspondence with the discharge lamps (1,) to (In). However, one AC power supply device may be provided for two or more discharge lamps 32. Figure 3 C2 AC power supply device in Example C2 (3,
) is shown.

The other AC power supply devices (3,) to (3□) are also similar to those in FIG. The AC power supply [1 nm (3,) consists of a separately excited two-stone transistor inverter (In) and a variable output frequency oscillator (OSC) that controls the oscillation of this inverter (In). Since the configuration of such an AC power supply device (31) is well known, the explanation will be omitted. In FIG. 3, (4) is the current limiting device of the discharge lamp (II), and (5) is the This is a transformer for heating the filament of an electric lamp (11).This transformer (5) is a C2 type so that it is supplied with power from a commercial power source.
61) is the discharge lamp (1,) and the father's device (31)
This is a switch that controls the output supply of the The output frequency of the AC paper source W (s,) and the Mij switch (6
The effects of I) and C will be described later.

(7) is a video signal generator, which in this embodiment generates a black and white television signal, and includes a radio frequency amplifier (8) for amplifying the signals from the antenna (A), zJh, etc., and a video detector (9).
And the video amplifier H has 6 winters.

The configuration of such video signal generator-1 (7) is well known. (11) is a control device that displays the video No. G4 occurrence (
7) The video signal from Japan is 60 Hz, and one video is 1/60 second14
period), the discharge lamp (11
) to (1n) C2, the discharge lamps C1, In other words, the light output of the discharge lamps (1□) to (1n) is controlled according to the white to black luminance indicated by the video signal, and the secondary light stage is 8. stage, 16 stages, 3
For example, there are two stages. The control device in X embodiment Address signal generator Q3i, ni that generates address signals corresponding to (l,) to (In)l
An A/D converter (+41), a discharge lamp (II
) to (In) are provided in pairs and are selected by the signal C2 from the address signal generator ([(8)). Controllers (15,) to (15n) that determine the supply period of the transformer voltage to F41J vehicle lights (1,) to (1n) C
) and switches (61) to (6n) for controlling the signals C from the controllers (15,) to (15n) to the two-way power supply devices (31) to (, (n)). be.

Each component of such a control device is well known.

Next (Part 2, Part 1) - Power supply device (3,) ~ (3n)
The output frequency of is set as ξ2. That is, since the scanning frequency of the video signal is 60H2, when the number of dimming stages is 8, it is an integral multiple of 60×8=480Hz. Here, it is set to 480 Hz.

The video signal generator (7) and control jB device circle as described above may be housed in or attached to the display panel (2), or provided in a separate operation room (not shown), as appropriate. It is. In addition, my father's school Ryu Genbi hJt (
31) ~(31) may be provided integrally with the lanterns (1,) ~(1,), or may be provided separately.

The operation will be described as a representative example of a discharge lamp (II). First, the video signal G2L6 from the video signal generator (7) is output from the address IA bow generator 0C2.
The fill device (15,) is selected, and the controller (15K) outputs a signal (() indicating the deepest dimming intensity as shown in FIG. The switch (61) outputs 1 from this controller 1 (15,).
It controls the supply of the output of the AC power supply (3,) to the discharge lamp (1,) by turning it on and off from No. i C2.

Therefore, the variable current voltage is supplied to the lamp only while the switch (61) is closed.In other words, when No. 6 indicates 1!4! degrees, the tributary Voltage supply period 1' When JJ is long and indicates #0, it is supply period 1.
This shortens ka.

The other discharge lamps (1,) to (In) are also each equipped with a controller (15).
1) (15n) L2 outputs the same amount of light and displays the image. And 1 ei (1/6o second)
When 1' is completed, M! is not displayed on the display panel (2) and is controlled in the same manner as above by the attached movie signal g2. is displayed.

The moon (1,) ~ (In)l2 is the deepest δ period (
In both cases, one cycle of paternal drainage pressure is provided. Therefore, the discharge lamps (11) to (In)i:l-! If positive and negative lamp currents flow, for example, only half a cycle of the current voltage or one and a half cycle is supplied (the two ratios are ℃
It is clear that the imbalance between positive and negative lamp currents can be significantly improved. Fig. 4 (al indicates one period of signal No. 6, tb+ indicates on/off of switch (61), tel indicates discharge lamp (1,) The delay of the lamp current (/field) depends on the current limiting device (4).

The father flow pressure supplied to the discharge lamps (II) to (in) does not have to start from zero. For example, it may be supplied from the π/2 phase of the two-current voltage (voltage port) in FIG. In this case as well, the lamp current H
The positive/negative asymmetry of can be improved.

FIG. 6 shows another embodiment. In this embodiment, the same parts as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted. In this embodiment, the control device'(11') has an oscillator (edge), and this oscillator outputs a signal with an oscillation frequency that is an even multiple of the number of dimming stages in synchronization with the synchronization circuit 0. On the other hand, the current transformer power supply (3t') ~
(3n') is a separately excited type inverter, which operates in oscillation by the output of the oscillator 121j. Therefore, as shown in FIG. 7, this embodiment can always supply the output voltage of the variable current power supply device mra+') to (3n') from the 0 phase to the discharge lamps (11) to (1n). It is something. Figure 7 (a) is a signal indicating synchronization of the video signal, bl is the oscillator (No. 48 of 2I (in the case of twice the number of sub-light stages)), and (C) is the output signal of the controller (15i). ,same(
d) shows the alternating voltage supplied to the open lamp (1,).

It should be noted that the present invention allows various modifications in addition to the above-described embodiments. As an analogy, the control device is a special publicity code 41-20845.
Other configurations such as those shown in Japanese Patent Publication No. 42-9222 are also possible. Furthermore, the means for controlling the supply of alternating current voltage to the discharge lamp may be one that controls the operation of the variable current power supply device itself. Furthermore, as a specific configuration for controlling, a transistor or the like other than a thyristor may be used. However, when using a transistor, when the supply voltage is cut off, the lamp current is also cut off, and! As shown in Figure g4 (C1), the lagging lamp current stops flowing and the effect of improving the positive/negative asymmetry of the lamp current is reduced, so it is preferable to delay the turn-off of the transistor so that the lagging lamp current is not cut off. .

As described in detail above, the present invention uses a discharge lamp as a display element, energizes the discharge lamp with a variable current power supply, and changes the output frequency of the variable current power supply to the scanning frequency of the video signal. Since it is set to an integral multiple of the product of and the number of dimming stages, the discharge lamp is always supplied with an AC voltage of integral cycles,
Since the positive/negative asymmetry of the lamp current can be reduced, it is possible to provide an image display device that can extend the life of the display element, ie, the air lamp.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the present invention, FIG. 2 is a block diagram showing the system configuration of the same embodiment, FIG. 3 is a circuit diagram showing a variable current power supply device used in the same embodiment, and FIG. 4 and 5 are waveform diagrams showing the operation of the same embodiment, and FIG. 6 is a block diagram showing the system configuration of another embodiment with some parts omitted.
FIG. 7 is a waveform chart showing the operation of the same embodiment. (1,)~(In)...Radiator light, (2)...Display panel, (3,)~(3nL (d,')~(3H')
・=Si-style Amogen equipment, (power...video signal ordering device, (11), (11')...control and wholesale device. Patent applicant: Toshiba Seisho Co., Ltd. Agent Patent attorney: Yoshi Ono 1) Kosai 3 Illustrations 4 Mouthfulness, S flashing V Otsu Nissai 7 Illustration procedure amendment (voluntary) 1. Indication of matter 1'1 Special revised application No. 148565 of 1982 2, title of the invention Video display device 3, person making the amendment What is the relationship? ) Toshiba Electric Materials Corporation Ritoutai II Representative: Inu Roku Sato 4, Agent Address: 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture 210 Toshiba Electric Materials Corporation Horiyo-cho Office Application, specification and drawings 6, contents of amendments (1) Correct and reverse the application form as shown in the attached sheet (engraved, no changes to the content). (2) Correct the entire text of Minga Gang as shown in the attached sheet (engraved, no changes to the contents). (3) Copy the drawings to the attached sheet and J3 Please make corrections (purification, no change in content).

Claims (4)

[Claims] (1) A display panel consisting of a large number of discharge lamps arranged, a father-flow source device that energizes the discharge lamps, a video signal generator that generates a video signal, and a A control device that controls the supply period of the current-changing voltage to each of the discharge lamps to control the preset dimming stage 1 of each of the discharge lamps: dimming the light and displaying an image on the display panel; An image display device comprising; the father-flow abrasive device having an output frequency set to an integral multiple of the product of the Mjl video signal scanning frequency and the number of dimming stages. (2) The video display device according to claim (1), wherein the AC source device includes an inverter. (3) The scope of claim (1) characterized in that the video signal generating device generates video No. 41 of a television (any one of No. 6, video signal, and movie signal).
) or the video display device described in (2). (4) The current transformer' power supply device supplies a transformer voltage to the discharge lamp from the 0 phase of the output voltage, according to any one of claims (1) to (3). video display device.