Lens group in use for projecting unit possessing parallel optical axis

Abstract

The invention relates to a lens group for a projector with parallel optical axes. By parallelizing the optical axis of the lens group downstream of the aperture and deviating from the lens group upstream of the aperture, the optical path difference of the light beams from each position of the image modulation device is made is compensated to modify the aberrations presented to the display.

Description

【Technical field】 [0001] The invention relates to a lens group, in particular to a lens group for a projection device with parallel optical axes. 【Background technique】 [0002] In the technical field of reconstructing and presenting images, currently common displays include cathode ray tube (CRT) displays, liquid crystal displays (LCD), television displays and other fixed-size displays, as well as non-fixed-size projection displays. For household sizes below 40 inches, flat-panel displays such as liquid crystal displays and plasma displays undoubtedly have advantages in terms of market price and acceptance. On the other hand, if the image data needs to be enlarged to a larger area of ​​50 inches or more, on the one hand, the panel manufacturing difficulty of the fixed-size flat-panel display device will increase, and the product yield rate will drop rapidly, so the production and manufacturing costs will increase significantly. It is estimated that the cost of such a facto...

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Problems solved by technology

[0009] On the other hand, if the liquid crystal device of the telecentric system is used as the optical machine of the spatial modulation device, because the liquid crystal device can only modulate the light transmittance of vertically incident polarized light, as for the light beam incident obliquely, it will cause light leakage and cannot be effectively detected. blocking, therefore, oblique incident or reflected beams cannot be used

like Figure 7 As shown, when the third light beam 45 projecting the chief ray at the lower end of this telecentric system optical engine 41 and the fourth light beam 46 projecting the chief ray at the upper end are parallel to each other, even if they also enter the lens group 42 and are reflected by the aspheric mirror 43 to display, but because the optical path of the fourth beam is significantly different from Image 6 The second light beam of the lens group 42 cannot form a triangle upstream, let alone form a similar shape with the triangle formed by the downstream light beams 45', 46', 44'; this kind of telecentric system cannot be applied to the above-mentioned structure

Therefore, the light beam traveling in an oblique direction used in this structure can only be used with an optomechanical structure such as a DLP structure, and cannot be extended to a telecentric system with a liquid crystal panel optomechanical structure

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