High performance, thermally-stabilized projection television lens systems
First Claim
1. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising in order from the system'"'"'s image side:
- (a) a first lens unit which primarily corrects aperture dependent aberrations, said first lens unit having an overall positive optical power and comprising in order from the lens system'"'"'s image side;
(i) a first lens subunit having a negative optical power O1 ; and
(ii) a second lens subunit having a positive optical power O2 ;
(b) a second lens unit which provides a substantial portion of the lens system'"'"'s overall positive optical power; and
(c) a third lens unit of negative optical power which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens systems, wherein the first lens subunit has an overall biconcave configuration.
4 Assignments
0 Petitions
Accused Products
Abstract
High performance projection lens systems for use in projection televisions are provided. The systems include A, B, C, and CR lens units. The A unit is composed of a negative subunit and a positive subunit, each of which have substantial optical power. The power of these subunits allows for better aberration control at greater field angles than that achieved with prior systems in which the elements of the A unit were of weak power. In certain embodiments, the lens system is thermally compensated through the use of a positive plastic lens element as part of the B unit.
98 Citations
66 Claims
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1. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising in order from the system'"'"'s image side:
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(a) a first lens unit which primarily corrects aperture dependent aberrations, said first lens unit having an overall positive optical power and comprising in order from the lens system'"'"'s image side; (i) a first lens subunit having a negative optical power O1 ; and (ii) a second lens subunit having a positive optical power O2 ; (b) a second lens unit which provides a substantial portion of the lens system'"'"'s overall positive optical power; and (c) a third lens unit of negative optical power which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens systems, wherein the first lens subunit has an overall biconcave configuration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising in order from the system'"'"'s image side:
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(a) a first lens unit which primarily corrects aperture dependent aberrations, said first lens unit having an overall positive optical power and comprising in order from the lens system'"'"'s image side; (i) a first lens subunit having a negative optical power O1, the ratio of the absolute value of O1 to O being greater than about 0.1; and (ii) a second lens subunit having a positive optical power O2, the ratio of O2 to O being greater than about 0.5; (b) a second lens unit which provides a substantial portion of the lens system'"'"'s overall positive optical power, said second lens unit comprising in order from the lens system'"'"'s image side; (i) a negative first lens element; (ii) a positive second lens element; and (iii) a positive third lens element; (c) a corrector lens unit having at least one aspheric surface; and (d) a third lens unit of negative optical power which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens system. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29)
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30. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising in .order from the system'"'"'s image side:
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(a) a first lens unit which primarily corrects aperture dependent aberrations, said first lens unit having an overall positive optical power and comprising in order from the lens system'"'"'s image side; (i) a first lens subunit composed of plastic and having a negative optical power O1 ; and (ii) a second lens subunit composed of glass and having a positive optical power (b) a second lens unit which provides a substantial portion [the majority]of the lens system'"'"'s overall positive optical power; (c) a corrector lens unit having at least one aspheric surface; and (d) a third lens unit of negative optical power which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens system. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising a series of lens elements arranged to form, in order from the system'"'"'s image side, at least the following lens units:
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(a) a first lens unit which primarily corrects aperture dependent aberrations; (b) a second lens unit which provides a substantial portion of the lens system'"'"'s overall positive optical power, said second lens unit comprising at least one plastic element having a positive optical power; and (c) a third lens unit of negative optical power which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens system; wherein; (i) the distance between the third lens unit and the lens element nearest the third lens unit on the image side of said unit is D; (ii) D increases as the temperature of the lens system increases from room temperature to the lens system'"'"'s operating temperature, said increase in D causing the focus of the lens system to change; and (iii) the positive optical power of said at least one plastic element of the second lens unit decreases as the temperature of the lens system increases from room temperature to the lens system'"'"'s operating temperature, said decrease in the positive optical power of the at least one plastic element of the second lens unit providing substantial compensation for the change in focus associated with the increase in D. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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- 57. In a projection television lens system which forms an image of an object and which includes (a) a housing, (b) a lens unit positioned in said housing at one end thereof which corrects for field curvature, and (c) other lens units including a power unit which provides substantial portion of the lens system'"'"'s positive optical power, the improvement which comprises a positive plastic lens element included among said other lens units which has a power and is positioned in said housing such that the change in its power with temperature substantially compensates for the change in the focus of the system which results from changes in the location of the power unit relative to the object with changes in temperature.
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62. A projection lens system for use with a cathode ray tube, said system having an overall positive optical power O and comprising in order from the system'"'"'s image side:
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(a) a first lens element composed of plastic; (b) a second lens element composed of glass; (c) a third lens element composed of glass; (d) a fourth lens element composed of glass; (e) a fifth lens element composed of plastic; (f) a corrector lens unit; and (g) a negative lens unit which is associated with the cathode ray tube during use of the lens system and which provides most of the correction for the field curvature of the lens system. - View Dependent Claims (63, 64, 65, 66)
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Specification