A two-chip LCD projector optical system

Abstract

The present invention discloses a two-chip LCD projector optical system, including an LCD light valve with red and green sub-pixels, a black-and-white LCD light valve, a red and green mixed light illumination device, a blue light illumination device, a color combining mirror, a projection lens, and a light valve electric driving device; the light emitted by the red and green mixed light illumination device is emitted to the color combining mirror after passing through the LCD light valve; the light emitted by the blue light illumination device is emitted to the color combining mirror after passing through the black-and-white LCD light valve, and the color combining mirror combines the light from the LCD light valve and the black-and-white LCD light valve, and then transmits the light to the projection lens. The optical system of the present invention reduces the loss of blue light and the total amount of blue light required by the system by multiples, significantly reduces the optical and electrochemical damage of blue light to various optical materials on the optical system of the projector, prolongs the service life of the projector, improves the output brightness of the projector, and increases user satisfaction.

Description

Technical Field

[0001] The invention relates to the technical field of projectors, and in particular to a two-chip LCD projector optical system. Background Art

[0002] After projectors entered the era of solid cold light sources such as LEDs, they have been restricted by technical conditions. While meeting the three-primary color ratio requirements of white balance, the luminous efficiency or energy density (light source radiation power / light source luminous area) of red and blue light sources are much higher than that of green light sources during the same period. Therefore, the output brightness of the projector is mainly determined by the efficiency or energy density of the green light source. Therefore, the brightness bottleneck of traditional projectors lies in how to maximize the brightness of the green primary color component in the output image.

[0003] To improve the output brightness of the projector, a two-chip LCD projector is disclosed in Patent No. CN201910490596.0. Figure 3 , a green light illumination device 5' illuminates a black-and-white LCD light valve 2' to produce a green image, and a red and blue mixed light illumination device 4' illuminates an LCD light valve 1' with red sub-pixels and blue sub-pixels to produce red and blue images, which are then projected through a projection lens 6' after being combined by a color combining device 3'. Green has a separate imaging channel, and its LCD light valve 2' has no CF (Color Filter) blocking loss, which guarantees the brightness of the green primary color component in the output image as much as possible, while red and blue are combined in one imaging channel. Although the red and blue color filters corresponding to the red and blue sub-pixels block their respective corresponding areas, causing a 50% loss of light (actually far more than 50%), the output brightness of the projector is still significantly improved. This two-chip LCD projector has significant advantages such as high efficiency and high brightness, and has achieved excellent innovation and breakthroughs.

[0004] As technology advances and the efficiency of green light sources increases, the shortcomings of this two-chip LCD projector become more and more obvious: Figure 4 Each pixel P' of the LCD light valve 1' includes a red sub-pixel (also known as a red color film, red color resistance, etc.) R' and a blue sub-pixel B', wherein the red sub-pixel R' is used to block the blue light of the illumination light and transmit the red light, and the blue sub-pixel B' is used to block the red light of the illumination light and transmit the blue light, which causes a 50% loss of the illumination light. Considering the black matrix BM (Black Matrix, Figure 4The LCD light valve 1' has a loss (not shown in the figure), and the loss of the LCD light valve 1' may be more than 50%. Taking a 2.2-inch FHD light valve with a BM line width of 3.5 microns as an example, the BM blocking loss is about 37.4%. The sub-pixels R' and B' each block the corresponding light. Finally, the total transmission efficiency of the LCD light valve 1' is about 31.3%.

[0005] See Figure 3 , while the black and white LCD light valve 2' still has a 2.2-inch FHD resolution and the BM also has a 3.5-micron line width, the BM blocking loss is approximately 25.5% (the number of columns of the black matrix in the horizontal direction is halved relative to the above-mentioned LCD light valve 1'), and thus the total transmittance of the LCD light valve 2' is approximately 74.5%.

[0006] If the white balance ratio of the three primary colors of the projector output image is 1:1:1 (dimensionless quantity), then for every 1 portion of green light required, 2.38 portions of blue light are required, and so on.

[0007] The higher the output brightness of the projector, the more blue light is required. In the entire optical system, 68.7% of the 2.38 parts of blue light are wasted. The shorter the wavelength of the light or the larger the short-wavelength light component (about 460nm is the limit, the light and electrochemical destructiveness of green light and red light is much weaker than that of blue light, 2-3 orders of magnitude lower), the stronger the light and electrochemical destructiveness to the plastic optical elements (such as plastic lenses), some brands of optical glass, optical films (such as anti-reflection films, dichroic films, etc.), LCD light valve transistor arrays, color filters, BM, liquid crystals, alignment films, polarizers and other materials in the projector optical system. For a projector with specific light resistance and electrochemical destructiveness, considering the durability of quality, the amount of blue light greatly limits the existing two-chip L CD Projector The output brightness of

[0008] To further improve the existing two-piece L CD Projector The output brightness of the projector is no longer the previous one of increasing the brightness of the green primary color light, but reducing the amount of the blue primary color light, that is, improving the efficiency of the blue lighting and imaging channels to reduce the total amount of blue light required, thereby reducing the light and electrochemical destructiveness of the blue light. Therefore, under the premise of ensuring the white balance of the projected image, how to increase the output brightness of the projector and how to minimize the component (amount) of blue light in the optical system to reduce the light and electrochemical destructiveness of the blue light have become problems that need to be solved by those skilled in the art. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a two-chip LCD projector optical system. The optical system of the present invention has a multiple reduction in the loss and total demand for blue light, thereby significantly reducing the optical and electrochemical damage of blue light to various optical materials on the projector optical system, extending the service life of the projector, improving the output brightness of the projector, and increasing user satisfaction.

[0010] In order to achieve the above-mentioned object, the present invention provides a two-chip LCD projector optical system, including an LCD light valve with red and green sub-pixels, a black and white LCD light valve, a red and green mixed light illumination device, a blue light illumination device, a color combining mirror, a projection lens and a light valve electric driving device;

[0011] The light valve electric driving device transmits the blue field image in the input video signal to the black-and-white LCD light valve, and synchronously transmits the red field and green field images to the LCD light valve;

[0012] The light emitted by the red and green mixed light illumination device is emitted to the color combining mirror after passing through the LCD light valve; the light emitted by the blue light illumination device is emitted to the color combining mirror after passing through the black-and-white LCD light valve. After the color combining mirror combines the light from the LCD light valve and the black-and-white LCD light valve, the light is transmitted to the projection lens and projected out.

[0013] After decoding the video signal input to the projector, the light valve electric driving device of the present invention extracts the blue field image and sends it to the black and white LCD light valve to drive it to display, extracts the red and green field images synchronously and sends them to the LCD light valve, correspondingly drives the red sub-pixel and green sub-pixel of the LCD light valve to display, and completes the full-color image display. The blue light of the present invention has a separate illumination imaging channel, and there is no color filter film blocking loss, so that the loss and total demand of the blue light of the optical system of the present invention are reduced by multiples, and the light and electrochemical damage of the blue light to each optical element on the optical system of the projector is significantly reduced, the service life of the projector is extended, and the user satisfaction is increased; the red and green colors are combined in one illumination imaging channel, and the red and green color filters corresponding to the red and green sub-pixels block their respective corresponding areas, causing light loss, but the wavelengths of the red and green lights are relatively far away from the blue light area, so the light and electrochemical damage to each optical material on the optical system is also very weak, thereby effectively improving the output brightness of the projector of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is a simplified schematic diagram of the optical system of the present invention.

[0016] Figure 2 It is a schematic diagram of the structure of the optical system of the present invention.

[0017] Figure 3 It is a structural schematic diagram of an existing two-chip LCD projector.

[0018] Figure 4 It is a schematic diagram of the structure of an existing LCD light valve. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings. The description in this part is only exemplary and explanatory and should not have any limiting effect on the protection scope of the present invention.

[0020] It should be noted that similar numbers and letters represent similar items in the following figures, so once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. It should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0021] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0022] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Specific embodiment:

[0024] See Figure 1 The present embodiment provides a two-chip LCD projector optical system, comprising an LCD light valve 1 with red and green sub-pixels, a black and white LCD light valve 2, a red and green mixed light illumination device 4, a blue light illumination device 5, a color combining mirror 3, a projection lens 6 and a light valve electric driving device 7.

[0025] The light valve electric drive device 7 transmits the blue field image in the input video signal to the black and white LCD light valve 2, and drives the pixel display on the black and white LCD light valve 2, synchronously transmits the red field and green field images to the LCD light valve 1, and drives the red sub-pixel and green sub-pixel of the LCD light valve 1 to display, so as to complete the full-color image display. At present, the light valve electric drive device 7 adopts the high-cost-effective chips such as V53 and V56 of M-star Company, completes the decoding conversion of various input video signals (such as HDMI, VGA, Video, etc.) to LVDS (Low-Voltage Differential Signaling) output, and then separates the blue field LVDS signal through the FPGA (Field Programmable Gate Array) circuit to send it to the black and white LCD light valve 2, and synchronously sends the red field and green field LVDS signals to the LCD light valve 1.

[0026] The light emitted by the red and green mixed light illumination device 4 is emitted to the color combining mirror 3 after passing through the LCD light valve 1; the light emitted by the blue light illumination device 5 is emitted to the color combining mirror 3 after passing through the black-and-white LCD light valve 2. After the color combining mirror 3 combines the light from the LCD light valve 1 and the black-and-white LCD light valve 2, the light is transmitted to the projection lens 6, and the image is projected through the projection lens 6.

[0027] In this embodiment, the blue light has a single illumination imaging channel, and the LCD light valve 2 is a black-and-white structure without a color filter film, so there is no color filter film blocking loss. At the same time, the blocking area of ​​BM is also halved in the horizontal direction (compared with the LCD light valve 1). Figure 3 and Figure 4Compared with the existing two-chip LCD projectors, if both use 2.2-inch FHD resolution and BM line width of 3.5 microns, when outputting the same brightness, Figure 3 and Figure 4 The existing two-chip LCD projector requires 2.38 parts of blue light, while this embodiment only requires 1 part of blue light, so that the loss of blue light and the total demand for blue light in the optical system of this embodiment are reduced exponentially, which significantly reduces the optical and electrochemical damage of blue light to various optical elements in the projector optical system, extends the service life of the projector, and increases user satisfaction.

[0028] The blue light illumination device 5 can be realized by many existing technical methods, such as the cost-effective method selected in this embodiment, i.e., a blue LED light source + a focusing device + a collimating (or focusing) device, etc., to perform Kohler or critical illumination on the black and white LCD light 2. Preferably, see Figure 2 The light source is a blue LED light source 51, the focusing device is a square cone (also commonly known as "V-shaped") condenser 52, and a collimating lens 53 is arranged on the exit surface of the square cone condenser 52, forming a cost-effective blue light illumination device 5 to perform Kohler illumination on the black-and-white LCD light valve 2. The blue polarizer 21 and the blue analyzer 22 are necessary accessories for the LCD imaging principle. In low-brightness projectors (such as output brightness below 200 lumens), they are generally directly made on the incident and exit surfaces of the LCD light valve. In projectors with higher brightness, they need to be peeled off and installed separately to facilitate ventilation and heat dissipation of the key raw materials of the blue polarizer 21 and the blue analyzer 22, namely the polarizer.

[0029] In this embodiment, red and green are combined in one photographic imaging channel, and the red and green color filters corresponding to the red and green sub-pixels block their respective corresponding areas, causing light loss. However, the wavelengths of red and green light are relatively far away from the blue light area, so the light and electrochemical damage to the optical materials in the optical system is also very weak, thereby effectively improving the output brightness of the projector of this embodiment. The red and green mixed light illumination device 4 can also be implemented in many existing technical ways, such as a red LED light source + focusing device, a green LED light source + focusing device, and after being mixed by a collimating (or focusing) device and a color combining device, the LCD light valve 1 is subjected to Kohler or critical illumination. Preferably, see Figure 2, a green LED light source 41, a red LED light source 401, a green square cone condenser 42, a red square cone condenser 402, a green collimating lens 43 is arranged on the exit surface of the green square cone condenser 42, a red collimating lens 403 is arranged on the exit surface of the red square cone condenser 402, a red and green light color combining mirror 14 (a 0.5 mm thick glass plate with a dichroic light splitting film, reflecting green light and transmitting red light) is selected as the color combining device, and after light combination, a relay lens 13 (the function is to slightly improve the system efficiency, which can be cancelled when pursuing low cost) is formed to form a cost-effective red and green mixed light illumination device 4, which performs Kohler illumination on the LCD light valve 1. Similarly, the polarizer 11 and the analyzer 12 are necessary accessories for the LCD display principle.

[0030] If the optical system of this embodiment has the same tolerance to blue light as the existing two-chip LCD projector, then compared with the technical approach of the existing two-chip LCD projector, the projector of this embodiment can output higher brightness, achieve further innovation and breakthroughs, and increase the competitiveness of the product.

[0031] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A two-chip LCD projector optical system, characterized in that: It comprises an LCD light valve (1) provided with red and green sub-pixels, a black and white LCD light valve (2), a red and green mixed light illumination device (4), a blue light illumination device (5), a color combining mirror (3), a projection lens (6) and a light valve electric driving device (7); The light valve electric driving device (7) transmits the blue field image in the input video signal to the black-and-white LCD light valve (2), and synchronously transmits the red field and green field images to the LCD light valve (1); The light emitted by the red and green mixed light illumination device (4) passes through the LCD light valve (1) and is then emitted to the color combining mirror (3); the light emitted by the blue light illumination device (5) passes through the black-and-white LCD light valve (2) and is then emitted to the color combining mirror (3); after the color combining mirror (3) combines the light from the LCD light valve (1) and the black-and-white LCD light valve (2), the light is transmitted to the projection lens (6) and projected out.

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