KR20000065125A - LCD projection lens - Google Patents

Abstract

The present invention relates to a projection lens for using a pixelated panel (LCD). The lens has two positive lens units U1 and U2 with aperture stops between them. The optical power of each of the units f1 and f2 is the focal length of each of the first lens unit U1 and the second lens unit U2 and the first lens unit U1 lies on the long conjugated surface of the system, When the second lens unit U2 is placed on the short conjugated surface, it is selected such that f1 is substantially shorter than f2. The ratio of f1 to f2 is preferably less than about 0.75.

Description

LC projection lens

Field of invention

The present invention relates to a projection lens, and more particularly to a projection lens that can be used in particular to form an image of an object consisting of pixels, such as a liquid crystal display (LCD). .

Background of the Invention

A projection lens system (hereinafter referred to as "projection system") is used to form an image of an object on a viewing screen. The basic structure of the system is shown in FIG. 7, where (10) is a light source (e.g. tungsten-halogen lamp), and (12) illumination optics (hereafter illumination) to form an image of the light source. The "output" of the system, 14 denotes the object to be projected (e.g. a matrix of on and off pixels of the LCD panel), and 13 It is a projection lens composed of multiple lens parts for forming an enlarged image of the object 14 on the screen 16.

Projection lens systems whose objects are on LCDs or other pixelated panels are used in a variety of applications, including data display systems. The projection lens system is for example a single projection lens which forms an image of either a single panel with red, green or blue pixels, or three individual panels each with the color. Is preferably used. For ease of explanation, while the description herein refers to a projection lens system using a single LCD panel, it will be appreciated that the present invention may also be used in systems using multiple panels and / or other pixelation types.

Summary of the Invention

The projection lens of the present invention comprises two positive lens units having an aperture stop between them. The optical power of each of the units is selected such that f1 is substantially shorter than f2, where f1 and f2 are the focal lengths of the first and second lens units, respectively, and the first lens unit is the long hole of the system. On the conjugate side, the second lens unit is on the short conjugated surface. In particular, the ratio of f1 to f2 is less than about 0.75 (see Table 7 when the second unit comprises a field lens, for example a Fresnel field lens, the value of f2). Is calculated without the field lens). In contrast, in the standard double gauss form, f1 is approximately equal to f2 or longer than f2.

The projection lens of the present invention may cover a wide field of view. They have a rear focal length that is approximately equal to the focal length of the lens. Each of the first and second lens units has at least one aspherical surface.

The first lens on the long conjugated surface of the stop may consist of a single quantity of parts. However, in order to obtain better correction of residual astigmatism and chromatic aberration, this unit is a leading negative element in which a positive element, which can be a color correcting doublet, is in close proximity. It may include. As shown in Tables 1 to 5, the spacing between the main negative component and the positive element is at most about 5% of the focal length of the first lens unit.

The second lens unit behind the aperture stop comprises a single quantity of parts having a color corrected bilens and at least one aspherical surface. When off-axis aberrations including coma and distortion as well as chromatic aberrations are remarkably corrected in the second lens unit, most of the correction of spherical aberration is obtained in the first lens unit. Lose.

1-6 are schematic side views of a projection lens made in accordance with the present invention,

7 is a schematic diagram of an overall projection lens system in which the projection lens of the present invention may be used.

The foregoing drawings, which are consistent with the specification and constitute a part thereof, together with the description, illustrate preferred embodiments of the invention and illustrate the principles of the invention. Of course, all drawings and descriptions illustrate the invention but are not limited thereto.

Description of Preferred Embodiments

1 through 6 illustrate various projection lenses made in accordance with the present invention. The corresponding general and optical properties are shown in Tables 1 to 6, respectively. The relationship between the lens units described above and the various components and surfaces of the lenses of Tables 1-6 is shown in Table 7 below.

The name HOYA or SCHOTT is used for the glass used in the lens system. Similar glasses made by other manufacturers can also be used to practice the present invention. Industrially applicable materials are used for styrene and acrylic parts.

Aspherical coefficients described in the table below are used in Equation I below.

Where z is the surface sag at distance y from the optical axis of the system, c is the curvature of the lens at the optical axis, and k is the conic constant.

In the following tables the designation “a” associated with various surfaces means an aspheric surface, ie at least one of D, E, F, G, H or I in the above formula is non-zero surface. The name "c" means a conic surface whose k value is not zero in the above equation. The name "f" refers to a Fresnel lens surface (the Fresnel lens is designated by the name "FL" in FIGS. 1 and 3). All units given in the tables below are in millimeters. The following tables are described on the assumption that light moves from left to right in the figures. In effect, the screen is on the left, the LCD panel is on the right, and the light moves from right to left.

Although embodiments of the present invention have been described and illustrated, those skilled in the art to which the present invention pertains may make various modifications from the foregoing without departing from the scope of the present invention.

Primary characteristics of the lens Power f ' 1pp 1'pp 0.77080E-02 129.74 85.332 -8.3775 Primary data, surface 1-4 K PP1 PP2 f ' 0.825105E-02 11.8672 -1.63760 121.20 Primary data, surface 6-11 K PP1 PP2 f ' 0.412919E-02 105.968 138.422 242.18

Primary characteristics of bilens Part number Surface number Power f ' 1pp 1'pp 3 4 6 8 -0.76835E-02 -130.15 -25.890 -48.110 Primary characteristics of the lens Power f ' 1pp 1'pp 0.77162E-02 129.60 83.934 -9.1868 Primary data, surface 1-4 K PP1 PP2 0.754400E-02 10.2057 -3.41220 Primary data, surface 6 to 10 K PP1 PP2 0.446394E-02 93.0606 115.413

Primary characteristics of the lens Power f ' 1pp 1'pp 0.77900E-02 128.37 71.383 -7.9999 Primary data, surface 4 to 9 K PP1 PP2 0.444232E-02 92.8040 107.813

Unit 1 Unit 2 Example number Surface number Surface number f1 f2 f f1 / f2 One 1 to 5 7 to 12 199.16 448.33 * 198.99 * 0.444 2 1 to 5 7 to 12 204.00 430.37 199.00 0.474 3 1 to 4 6 to 11 115.38 257.84 * 129.60 * 0.447 4 1 to 4 6 to 11 121.20 242.18 129.74 0.500 5 1 to 4 6 to 10 132.56 224.02 129.60 0.592 6 1 to 2 4 to 9 135.95 225.11 128.37 0.604

The value * was calculated without the Fresnel lens because the Fresnel lens is basically a field lens where the inlet and outlet pupils of the lens of the illumination system are connected. As above, the Fresnel lens has a minimum effect on the overall focal length of the lens, but has a large effect on the value of f2, and this effect does not represent the actual function of the f2 unit.

Claims (13)

Sequentially from the end of the image to the end of the object a) a first lens unit having a positive optical power and a focal length f1; b) a second lens unit having a positive optical power and a focal length f2 substantially shorter than f1, An aperture stop is positioned between the first and second lens units. The projection lens for forming an image of an object. The projection lens of claim 1, wherein the ratio of f1 to f2 is less than 0.75. 2. The projection lens of claim 1, wherein the lens has a rear focal length that is approximately equal to the focal length of the lens. The projection lens of claim 1, wherein each of the first and second lens units has at least one aspherical surface. A projection lens according to claim 1, wherein said first lens unit consists of a single amount of lens parts. The method of claim 1, wherein the first lens unit is sequentially from the image end a) negative lens component; And b) a projection lens comprising a positive lens subunit. 7. The projection lens of claim 6, wherein the positive lens subunit is slightly spaced apart from the negative lens component. 7. A projection lens according to claim 6, wherein said positive lens subunit is a color corrected bilens. 2. A projection lens according to claim 1, wherein said second lens unit comprises a color correcting bilens and a positive lens component having at least one aspherical surface. 7. A projection lens according to claim 6, wherein said second lens unit comprises a color correcting bilens and a positive lens component having at least one aspherical surface. 8. A projection lens according to claim 7, wherein said second lens unit comprises a color correcting bilens and a positive lens component having at least one aspherical surface. 9. A projection lens according to claim 8, wherein said second lens unit comprises a color correcting bilens and a positive lens component having at least one aspherical surface. (a) an illumination system comprising a light source and an illumination element for forming an image of the light source; (b) a pixelated panel comprising the object; And (c) A projection lens system for forming an image of an object, comprising the projection lens of claim 1.