KR20000051734A - Apparatus for controlling light capacity in liquid crystal display projection television - Google Patents

Abstract

PURPOSE: An apparatus for controlling the intensity of radiation of a LCD projection television is provided to detect a Y signal related to brightness among a mixed image signal received from a television transmitting part and control the intensity of radiation of a lamp, which is a light source, according to the voltage level of the detected Y signal. CONSTITUTION: An apparatus for controlling the intensity of radiation of a LCD projection television includes a color regenerating part(11), an integration circuit part(14), a comparing part(15), an intensity of radiation control signal generating part(16) and an intensity of radiation controlling part(17). The color regenerating part outputs R, G, and B signals among a brightness signal and a color difference signal when the brightness signal and the color difference signal are detected in a mixed image signal. The integration circuit part integrates the brightness signal output from the color regenerating part and detects a direct current voltage level. The comparing part compares a direct current voltage output from the integration circuit part with a pre-established standard voltage. The intensity of radiation control signal generating part generates a signal to control the intensity of radiation by a signal output from the comparing part. The intensity of radiation controlling part controls the intensity of radiation of the lamp according to the controlling signal.

Description

Light quantity control device of LCD projection TV {APPARATUS FOR CONTROLLING LIGHT CAPACITY IN LIQUID CRYSTAL DISPLAY PROJECTION TELEVISION}

The present invention relates to an LCD projection television, and more particularly, to control an amount of light of an LCD projection television to display an optimal screen state by adjusting a brightness of a lamp according to a luminance signal related to brightness among signals input to an LCD projection television. Relates to a device.

Recently, with the development of the information industry, the demand for image display means having a larger screen has been on the rise, but the direct view type cathode ray tube composed of a television receiver screen, which has been a general image display means, has a large cathode ray tube itself in order to enlarge the screen. Due to various realistic constraints that had to be produced, there was a limit to the degree of enlargement.

In addition, even if it is possible to produce a large-sized cathode ray tube to some extent by overcoming the technical difficulties described above, another limitation in producing a television set having a large cathode ray tube as a screen due to the increase in the load of the cathode ray tube Due to the technical difficulties due to factors, there was no limit to the production of a television having a large cathode ray tube on the screen.

Under such a background, an image projection system such as a projection television has been developed and put into practical use as a way to obtain a larger screen by overcoming the difficulties of various technical factors.

Such an image projection system generates an image by means of image display means such as a specially made small cathode ray tube, a liquid crystal display device, or a polymer dispersed liquid crystal display panel, and enlarges the image by using an optical lens, for example, a projection lens. As a system of projecting on a large screen, the demand is increasing day by day in the advantage of obtaining a large screen that can meet the needs of consumers.

A configuration of a liquid crystal display (LCD) projection television using a lamp as a light source among the projection televisions will be described with reference to FIG. 1.

In color television, the video signal is transmitted by converting the signals of three primary colors of RED, GREEN, and BLUE into luminance signals Y and color difference signals I and Q. The carrier is loaded on a color carrier, which is a carrier, (also called a 'carrier color signal'), and then multiplexed and transmitted. On the other hand, the color television receiver demodulates the color difference signal by separating the carrier color signal from the composite video signal transmitted as described above, and detects and displays three primary colors of R, G, and B.

First, a color demodulator 1 for demodulating the luminance signal and the color difference signal by separating the carrier color signal from the composite video signal transmitted from the television transmission side, and the luminance signal Y and the color difference signal RY, BY demodulated by the color demodulator 1 After gamma correction, contrast and brightness are adjusted by receiving the color reproduction unit 2 which receives the received R, G and B signals and the R, G and B signals output from the color reproduction unit 2 LCD drive 3 which outputs R, G, B signals inverted / non-inverted in synchronization with a timing generator to LCD panel 4, and a light source that irradiates light for displaying an image on an external screen In-lamp 7, lamp driver 6 for turning on / off lamp 7 by power supply 5, and in front of lamp 7 and outputting signals from LCD drive 3 LCD panel 4 for displaying a predetermined image, and is installed in front of the LCD panel 4 to the external screen It consists of an image to be used in focusing (focusing) projector lens (8) and a screen (9) where the image is displayed is projected through a projection lens 8 to.

In the conventional LCD projection television configured as described above, when power is supplied from the power supply unit 5, the lamp driving unit 6 turns on the lamp 7, and thus white light is emitted from the lamp 7. This white light is converted into parallel beams through a relay lens (not shown) and a collimation lens (not shown), and the converted parallel beams are converted into respective dichroic mirrors (not shown). In this case, light of a unique color is reflected, and the R, G, and B beams reflected from the dichroic mirror are focused on a pixel of each corresponding LCD panel 4.

In addition, the R, G, and B beams reflected from the dichroic mirror and focused on the LCD panel 4 according to the image signal incident on the LCD panel 4 from the LCD drive 3 are reproduced and projected as predetermined images. It is displayed on the screen 9 through the lens 8.

However, according to the conventional LCD projection television, the following problems occur.

That is, the lamp, which is a light source that emits light to the LCD panel, is turned on / off by the control of the lamp driver to emit a constant amount of light. Therefore, a black background is too dark to lock the black level, and when the dark screen is up, a saturation occurs on the bright screen.

Accordingly, an object of the present invention is to solve such a problem, and an object of the present invention is to detect a Y signal related to brightness among synthesized video signals transmitted from a television transmission side, and determine a light source according to the detected voltage level of the Y signal. An object of the present invention is to provide a light quantity control apparatus of an LCD projection television that can control a light quantity of a lamp.

1 is a schematic block diagram of a conventional LCD projection television;

Figure 2 is a block diagram showing the light amount control device of the LCD projection television according to the present invention.

A feature of the present invention for achieving the above object is that, if the luminance signal and the color difference signal are detected by separating the carrier color signal from the composite video signal transmitted from the television transmission side, the R, G, B signal is output from the luminance signal and the color difference signal. An integrating circuit for detecting a DC voltage level by integrating the output color reproducing unit, a luminance signal output from the color reproducing unit, a comparing unit for comparing the DC voltage output from the integrating circuit unit with a preset reference voltage, A light quantity control signal generator for generating a light quantity control signal by an output signal; And a light amount adjusting unit for adjusting the light amount of the lamp by the control signal of the light amount control signal generating unit.

Preferably, the light amount control unit is a power supply for supplying power to drive the lamp, a voltage converter for changing the voltage supplied from the power supply by the signal output from the light amount control signal generator, and the output from the voltage converter It characterized in that it comprises a lamp driving unit for driving the lamp at a changed voltage.

Preferably, if the signal transmitted from the light quantity control signal generator is a high signal, the voltage converter reduces the voltage applied to the lamp driver to drive the lamp darkly, and if the signal transmitted from the light quantity control signal generator is a low signal, In order to drive the lamp brightly characterized in that for increasing the voltage applied to the lamp driver.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a light amount control apparatus of an LCD projection television according to the present invention.

Referring to FIG. 2, a light amount control apparatus according to the present invention includes a color demodulator 10 for demodulating a luminance signal and a color difference signal by separating a carrier color signal from a composite video signal transmitted from a television transmitter, and a color demodulator 10. Receives the luminance signal Y and the color difference signal RY, BY demodulated by the color reproduction unit 11 for outputting the R, G, and B signals, and the R, G, B signals output from the color reproduction unit 11; LCD drive 12 which outputs inverted / non-inverted R, G, B signals synchronized with timing generator to LCD panel 13 after gamma correction, contrast and brightness adjustment, and color scheme Integral circuit section 14, which receives the integrated brightness signal demodulated by the rough section 10 and detects the DC voltage level, compares the DC voltage output from the integrated circuit section 14 with the preset reference voltage V _ref . A light quantity control signal is generated by the signal output from the unit 15 and the comparison unit 15. The light amount control signal generator 16, the light amount control unit 17 for adjusting the light amount of the lamp 18 by the control signal of the light amount control signal generator 16, and the light amount control unit 17 A lamp 18 which is a light source that emits light for displaying an image on an external screen, and an LCD panel installed in front of the lamp 18 and displaying a predetermined image according to a signal output from the LCD drive 12. 13, a projection lens 19 installed in front of the LCD panel 13 to focus an image projected on an external screen, and a screen 20 on which an image projected through the projection lens 19 is displayed. It is composed of

Here, the light amount adjusting unit 17 may include a power supply unit 22 for supplying power for driving the lamp 18 used as a light source, and a voltage value input from the power supply unit 22. And a voltage converter 21 for converting the signal by the signal output from the (), and a lamp driver 23 for driving the lamp by the output signal of the voltage converter 21.

Looking at the operation of the light amount control device of the LCD projection television of the present invention configured as described above are as follows.

Here, the description of the operation of the same configuration as in the prior art is omitted, and an integrated circuit unit for explaining a light amount control device for controlling the light amount of the lamp 18 which is a light source for irradiating light to the LCD panel 13 which is the gist of the present invention ( 14), the operation of the comparator 15, the light amount control signal generator 16 and the light amount control unit 17 will be described.

First, when the luminance signal and the color difference signal are demodulated by the color demodulation unit 10 of the composite video signal, the integrating circuit unit 14 receives the demodulated luminance signal and integrates it to detect the DC voltage. The detected DC voltage is input to the comparator 15, and the comparator 15 compares the input DC voltage with a preset reference voltage and inputs a comparison result to the light quantity control signal generator 16. Here, the reference voltage is preset to a suitable value suitable for the projection television.

The light quantity control signal generator 16 generates a high signal when the DC voltage input by the signal input from the comparator 15 exceeds the reference voltage, that is, when the luminance signal is bright, and the input DC voltage is referenced. If it is less than the voltage, that is, if the input luminance signal is dark, a low signal is generated.

When the signal output from the light quantity control signal generator 16 is high, the light amount adjusting unit 17 reduces the light amount of the lamp 18 used as a light source to prevent saturation on a bright screen, and darkens it. If the signal output from the light quantity control signal generator 16 is low, the light amount of the lamp 18 is increased to make it brighter to prevent the black level from being locked in a dark screen.

That is, the control signal output from the light quantity control signal generator 16 changes the voltage of the voltage converter 21 inside the light quantity control unit 17, and accordingly, the driving voltage of the lamp driver 23 is changed. The amount of light of the lamp 18 used as the light source is adjusted.

For example, when the DC voltage level detected by the integrating circuit section 14 exceeds the reference voltage, the light quantity control signal generating section 16 outputs a high signal, and the voltage converting section 21 according to the input high signal. The voltage supplied from the power supply unit 22 is reduced by a certain amount and applied to the lamp driver 23, and the lamp driver 23 drives the lamp 18, which is used as a light source, by a predetermined amount to reduce the amount of the lamp. Reduce the brightness

Therefore, the brightness of the lamp for irradiating light to the LCD panel is not fixed, but the optimum screen state can be displayed by variably adjusting the brightness of the lamp according to the input luminance signal.

As described above, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

As described above, since the light quantity control apparatus of the LCD projection television according to the present invention controls the amount of light irradiated to the LCD panel according to the luminance signal indicating the brightness among the composite image signal received from the television receiver, black on a dark screen There is an advantage to prevent the level from being locked or saturation on a bright screen.

Claims (3)

A color reproduction unit that separates the carrier color signal from the composite video signal transmitted from the television transmission side and outputs R, G, and B signals from the luminance signal and the color difference signal; An integrating circuit unit for detecting a DC voltage level by integrating the luminance signal output from the color reproducing unit; A comparison unit comparing the DC voltage output from the integration circuit unit with a preset reference voltage; A light quantity control signal generator for generating a light quantity control signal by the signal output from the comparator; And a light amount control unit for adjusting the light amount of the lamp according to the control signal of the light amount control signal generator. The method of claim 1, wherein the light amount adjusting unit, A power supply for supplying power to drive the lamp, a voltage converter for changing the voltage supplied from the power supply by a signal output from the light quantity control signal generator, and a changed voltage output from the voltage converter. And a lamp driving unit for driving the lamp. The method of claim 2, wherein the voltage conversion unit, If the signal transmitted from the light amount control signal generator is a high signal, the voltage applied to the lamp driver is reduced to drive the lamp darkly, and if the signal transmitted from the light amount control signal generator is a low signal, the lamp And increasing the voltage applied to the lamp driver to brightly drive the light quantity control circuit of the LCD projection television.