KR100481980B1 - Projection lenses for a projection TV - Google Patents

Abstract

The present invention relates to a projection lens system of the projection TV, occupies most of the total power of the lens system and the aspherical lens-shaped first lens (L1) having a relatively weak power (P1) in turn across the conduit of the water tube on the screen side 2nd lens L2 of the double-sided convex lens shape which has a considerably large power P2, the aspherical 3rd lens L3 which has comparatively weak power P3, and very weak power P4, By selecting the optical characteristic of the lens used in the projection TV with the aspheric lens-shaped fourth lens L4 for correcting the image surface curvature, it is possible to obtain a higher resolution and obtain a clearer picture quality.

Description

Projection lenses for a projection TV

The present invention relates to a projection lens system of a projection TV, and to increase the resolution by appropriately setting the power (inverse of the focal length) ratio range of a lens disposed in a large number over the conduit of the receiving tube on the screen side of the projection TV receiver. Related to Projection TV's projection lens system.

Projection TV uses a projection optical system such as a lens or a mirror to enlarge an image reproduction surface of a television receiver to obtain an image that cannot be obtained with a small screen. It is a device that enlarges and projects on the screen to obtain a picture of a large screen.

The resolution of the image to be reproduced is determined according to the type or arrangement of the projection lens.

As for the technology related to the projection lens system of the projection TV, the patent application No. 1986-7972 (September 24, 1986), the patent application No. 1992-19859 (October 28, 1992), the patent application No. 2000-7000256 ( January 10, 2000, etc. has been proposed.

The projection lens system of the Projection TV has been researched in the direction of miniaturization by reducing the number of lenses required, and having a higher resolution to obtain excellent image quality.

According to the optical principle, the technology to reduce the number of lenses as much as possible has reached the limit at present, and in contrast, the technology of realizing higher resolution by the proper selection of the optical characteristics of the lens used in the projection TV is still subject to various studies. have.

Accordingly, the present inventors have studied the projection TV system of the projection TV having higher resolution by appropriate selection of the optical characteristics of the lens.

The present invention has been invented under the above-mentioned object, and an object thereof is to provide a projection TV projection lens system having a higher resolution by appropriate selection of the optical characteristics of the lens used in the projection TV.

According to one aspect of the present invention for achieving the above object, the projection TV projection lens system according to the present invention is the power (inverse of the focal length) of the entire lens system as P0, and across the surface of the receiving tube from the screen side An aspheric lens-shaped first lens L1 having a relatively weak power P1 in turn, a second lens L2 having a biconvex lens shape having a significantly larger power P2 that occupies most of the total power of the lens system; A projection lens comprising a third lens L3 having an aspheric lens shape having a relatively weak power P3, and a fourth lens L4 having an aspheric lens shape having a very weak power P4 and correcting image curvature. In the projection lens system, the ratio of P1 to P0 is in the range of -0.2 ≦ P1 / P0 ≦ 0.05.

According to a further aspect of the invention, the projection lens system of the projection TV according to the present invention has a ratio of P2 to P0 of 0.8 ≦ P2 / P0 ≦ 0.99, wherein the ratio of P3 to P0 is 0.25 ≦ P3 / P0. It is characterized in that it further comprises a range of ≤ 0.45.

According to a further aspect of the invention, the projection lens system of the projection television according to the invention has a ratio of the distance t between the third lens L3 and the fourth lens L4 to the focal length F of the entire lens system. It is characterized by the range of 0.35 <t / F <0.58.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily understand and reproduce the present invention.

1 is a cross-sectional view of the lens arrangement of the projection TV projection lens system according to the present invention.

As shown in the figure, a projection lens system of the projection TV according to the present invention comprises an aspherical lens-shaped first lens L1 having a relatively weak power P1 in turn across the conduit of the water tube on the screen side, and the entire lens system. Second lens L2 of double-sided convex lens shape having a fairly large power P2 occupying most of the power, aspherical third lens L3 having relatively weak power P3, and very weak power. A fourth lens L4 having an aspherical lens shape having P4 and correcting image curvature is provided.

In the drawings, S1 to S10 are surface numbers. The power P1 to P4 is the inverse of the focal length of each lens.

In the projection lens system of the projection TV according to the present invention, when the power (inverse of the focal length) of the entire lens system is P0, the ratio of the power P1 of the first lens L1 to the power P0 of the entire lens system is -0.2. It exists in the range of <P1 / P0 <0.05.

Further, the ratio of the power P2 of the second lens L2 to the power P0 of the entire lens system is in the range of 0.8 ≦ P2 / P0 ≦ 0.99, and the third lens L3 to the power P0 of the entire lens system. The power P3 ratio is in the range 0.25? P3 / P0? 0.45.

In addition, in the projection lens system of the projection TV according to the present invention, the ratio of the interval t between the third lens L3 and the fourth lens L4 to the focal length F of the entire lens system is 0.35 <t / F <0.58 Characterized in that it exists in the range of.

Hereinafter, the advantages of the projection TV projection lens system having the lens arrangement shown in FIG. 1 will be described through specific embodiments existing within the above range.

FIG. 2 is a data table according to the first embodiment of the projection TV projection lens system according to the present invention, wherein the upper table shows data of a paraxial system that handles lens areas near the optical axis, and the lower table shows lens areas near the optical axis. External aspheric system data is displayed. In FIG. 2, S1 to S10 are surface numbers.

Referring to the table at the top of FIG. 2, the screen not shown in the drawing has a radius of curvature (∞), that is, a plane, and an effective diameter (crab radius) of 576.1 mm, which is an effective radius that is optically compensated for performance. The distance (surface spacing) on the optical axis to the S1 surface of the first lens L1 is 733.14 mm, and the refractive index between them (air) is 1.0.

The radius of curvature of the S1 surface of the first lens L1 is 63.40846 mm, the effective diameter is 43.2 mm, the distance on the optical axis between the lens surfaces S1 and S2 is 5.00 mm, and the refractive index therebetween is 1.493907.

The radius of curvature, the effective diameter, the distance on the optical axis, and the refractive index of the remaining S2 to S10 planes are shown in the drawings, and thus detailed description thereof will be omitted.

Referring to the table at the bottom of FIG. 2, aspheric coefficients for the S1 and S2 surfaces of the first lens L1, the S5 and S6 surfaces of the third lens L3, and the S7 surface of the fourth lens L4. (aspherical coefficient) is indicated.

In FIG. 2, K represents a conic coefficient, and A to E represent aspherical coefficients.

The surface sag value required for designing the aspherical lens is determined by the following equation.

Where Z is the surface sag value, K is the conic coefficient, c is the reciprocal of the radius of curvature, and h is the distance from the center (optical axis) to any point on the sphere. aperture distance), A to J are aspherical coefficients.

3 is an MTF characteristic diagram of the first embodiment shown in FIG.

The MTF (Modulation Transfer Function) characteristic chart is a measure of the screen resolution, and the higher the screen resolution, the better and clearer the image.

In FIG. 3, the X axis represents a spatial frequency, and the Y axis represents a resolution of 0 to 1.

A 0 on the Y axis means that the image cannot be resolved, and a 1 means 100% resolution.

In the drawing, the solid line represents the meridion plane (T) and the dotted line means the equator plane (R).

As shown in the figure, the resolution is high in the region of low spatial frequency, and the resolution is low in the region of high spatial frequency.

In the projection lens system of the projection TV according to this embodiment, it can be seen that the resolution of the meridion plane T and the equator plane R of each field is 0.4 or more in the spatial frequency band of 6 cycles / mm.

Therefore, the spatial frequency of 6 cycles / mm, that is, about 1200 images (rows) when viewed on the screen of the TV receiver means that the high quality image can be obtained. In other words, this means that the projection TV projection lens system according to this embodiment can be applied to a large TV.

Each field (optical axis, 0.3, 0.7, 0.8, 1.0) in the drawing means an angle of view as shown in FIG.

4 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left of the characteristic diagram of the first embodiment shown in FIG.

The light rays incident on the lens do not meet at one point in the image space, and there is a distance difference between the focal points of the light rays. This difference is called Longitudinal Spherical Aberration.

4 shows longitudinal spherical aberration, wherein the X-axis is spherical aberration and the Y-axis is a numerical value in which the lens height is standardized from 0 to 1. FIG.

In the drawing, it can be seen that the light rays incident near the optical axis are located far from the lens, and the light rays incident to a part far from the optical axis are located near the lens.

The smaller this spherical aberration, the smaller the better.

Light rays incident from points off the optical axis appear as ellipses in phase space, and this difference is called astigmatism.

4 shows astigmatism, the X axis represents astigmatism, and the Y axis represents image height (angle of view).

In the figure, 63.50 represents 1.0 field, 47.63 represents 0.8 field, 31.75 represents 0.7 field, 15.88 represents 0.3 field, and 0 represents an optical axis.

The solid line shows the astigmatism with respect to the equator plane (R), and the dotted line shows the meridion plane (T).

The smaller the astigmatism is, the smaller the better.

4 shows the distortion aberration (Distortion), the X axis represents the distortion aberration, the Y axis represents the image height (view angle).

In the figure, 63.50 represents 1.0 field, 47.63 represents 0.8 field, 31.75 represents 0.7 field, 15.88 represents 0.3 field, and 0 represents an optical axis.

The smaller the distortion aberration, the smaller the better.

5 is a data table according to a second embodiment of a projection lens projection lens system according to the present invention.

The embodiment shown in FIG. 5 interprets the table in the same manner as in the first embodiment shown in FIG. 2 and obtains the surface segment value using the same equation as described above, and thus a detailed description thereof will be omitted.

FIG. 6 is an MTF characteristic diagram of the second embodiment shown in FIG.

FIG. 7 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left in the characteristic diagram of the second embodiment shown in FIG.

8 is a data table according to a third embodiment of a projection lens projection lens system according to the present invention.

The embodiment shown in FIG. 8 interprets the table in the same manner as in the first embodiment shown in FIG. 2 and obtains the surface segment value using the same equation as described above, and thus a detailed description thereof will be omitted.

FIG. 9 is an MTF characteristic diagram for the third embodiment shown in FIG.

FIG. 10 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left in the characteristic diagram of the third embodiment shown in FIG.

11 is a data table according to the fourth embodiment of the projection lens projection lens system according to the present invention.

The embodiment shown in FIG. 11 interprets the table in the same manner as in the first embodiment shown in FIG. 2 and obtains the surface segment value using the same equation as described above, and thus a detailed description thereof will be omitted.

FIG. 12 is an MTF characteristic diagram for the fourth embodiment shown in FIG.

FIG. 13 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left in the characteristic diagram of the fourth embodiment shown in FIG.

14 is a data table according to a fifth embodiment of a projection lens projection lens system according to the present invention.

The embodiment shown in FIG. 14 interprets a table in the same manner as in the first embodiment shown in FIG. 2 and obtains a surface segment value using the same equation as described above, and thus a detailed description thereof will be omitted.

FIG. 15 is a MTF characteristic diagram for the fifth embodiment shown in FIG.

FIG. 16 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left in the characteristic diagram of the fifth embodiment shown in FIG.

17 is a data table according to a sixth embodiment of a projection lens projection lens system according to the present invention.

The embodiment shown in FIG. 17 interprets a table as in the first embodiment shown in FIG. 2 and obtains a surface segment value using the same equation as described above, and thus a detailed description thereof will be omitted.

FIG. 18 is a MTF characteristic diagram for the sixth embodiment shown in FIG.

FIG. 19 is a characteristic diagram showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left in the characteristic diagram of the sixth embodiment shown in FIG.

Each of the embodiments shown in FIGS. 5 to 19 differs only in data values from the first embodiment, and MTF characteristics, spherical aberration, astigmatism, and distortion are obtained in the same manner as in the first embodiment described above. Detailed description will be omitted.

20 is a table summarizing the results of the first to sixth embodiments.

In FIG. 20, P0 to P3 represent the inverse of the focal length, F the focal length of the whole optical system, and t represents the distance between the third lens and the fourth lens.

As shown in the figure, the first to sixth embodiments include a ratio of P1 to P0 in a range of -0.2 ≦ P1 / P0 ≦ 0.05, and a ratio of P2 to P0 is 0.8 ≦ P2 / The ratio of P3 to P0 in the range of 0.25 ≦ P3 / P0 ≦ 0.45, wherein the third lens L3 and the fourth for the focal length F of the entire lens system It can be seen that the ratio of the interval t with the lens L4 is in the range of 0.35 <t / F <0.58.

Therefore, the MTF characteristic of each of the above-described embodiments and the characteristic diagrams for longitudinal spherical aberration, astigmatism, and distortion aberration can be seen that the resolution is higher than that of the prior art. Therefore, the projection TV projection lens system according to the present invention is conventional. You get clearer picture quality.

As described above, the projection lens system of the projection TV according to the present invention has a useful effect of obtaining a higher resolution by obtaining a higher resolution by appropriate selection of the optical characteristics of the lens used in the projection TV.

Although the present invention has been described with reference to the accompanying drawings, it will be apparent to those skilled in the art that various modifications may be made therein without departing from the scope of the invention, which is covered by the following claims.

1 is a cross-sectional view of a lens arrangement of a projection lens system of a projection TV according to the present invention.

2 is a data table according to the first embodiment of the projection TV projection lens system according to the present invention.

3 is an MTF characteristic diagram for the first embodiment shown in FIG.

FIG. 4 is a characteristic diagram of the first embodiment shown in FIG. 2, showing characteristic spherical aberration, astigmatism, and distortion aberration from the left.

5 is a data table according to a second embodiment of the projection TV projection lens system according to the present invention.

6 is an MTF characteristic diagram for the second embodiment shown in FIG.

FIG. 7 is a characteristic diagram of a second embodiment shown in FIG. 5, showing characteristic spherical aberration, astigmatism, and distortion aberration from the left; FIG.

8 is a data table according to a third embodiment of the projection lens projection lens system according to the present invention.

9 is an MTF characteristic diagram of the third embodiment shown in FIG.

FIG. 10 is a characteristic diagram of the third embodiment shown in FIG. 8, showing characteristic spherical aberration, astigmatism, and distortion aberration from the left.

11 is a data table according to a fourth embodiment of the projection lens projection lens system according to the present invention.

12 is an MTF characteristic diagram for the fourth embodiment shown in FIG.

FIG. 13 is a characteristic diagram showing a fourth embodiment shown in FIG. 11, showing longitudinal spherical aberration, astigmatism, and distortion aberration from the left; FIG.

14 is a data table according to a fifth embodiment of a projection lens projection lens system according to the present invention.

FIG. 15 is an MTF characteristic diagram for the fifth embodiment shown in FIG.

FIG. 16 is a characteristic diagram of the fifth embodiment shown in FIG. 14, showing characteristic spherical aberration, astigmatism, and distortion aberration from the left;

17 is a data table according to a sixth embodiment of the projection lens projection lens system according to the present invention.

18 is an MTF characteristic diagram of the sixth embodiment shown in FIG. 17;

FIG. 19 is a characteristic diagram showing the spherical aberration, the astigmatism, and the distortion aberration from the left in the sixth embodiment shown in FIG. 17;

20 is a table summarizing the results of the first to fifth embodiments.

Claims (3)

delete delete Aspheric lens-shaped first lens L1 having a power P (inverse of the focal length) of the entire lens system and having a relatively weak power P1 compared to the power of the entire lens system in order from the screen side to the water tube. And a second lens L2 of double-sided convex lens shape having a substantially large power P2 substantially occupying most of the total power of the lens system, and an aspherical surface having a relatively weak power P3 compared to the power of the entire lens system. Projection TV projection lens having a lens-shaped third lens (L3) and an aspherical lens-shaped fourth lens (L4) having a very weak power (P4) compared to the power of the entire lens system and corrects image curvature In the system, The ratio of P1 to P0 is in the range of −0.2 ≦ P1 / P0 ≦ 0.05; The ratio of P2 to P0 is in the range 0.8 ≦ P2 / P0 ≦ 0.99; The ratio of P3 to P0 is in the range of 0.25 ≦ P3 / P0 ≦ 0.45; The ratio of the interval t between the third lens L3 and the fourth lens L4 to the focal length F of the entire lens system is in the range of 0.35 <t / F <0.58; Projection TV projection lens system, characterized in that.