CN105652421A - Camera lens for digital projector - Google Patents

Abstract

The invention discloses a lens for a digital projector, which comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, The seventh lens, the eighth lens and the ninth lens; an aperture stop is arranged between the fourth lens and the fifth lens, and the aperture stop is close to the fifth lens; the invention adopts an image-side telecentric optical path, and controls CRA matches the lighting system within a certain range to achieve good image contrast and high energy utilization; the first lens and the eighth lens near the screen adopt aspheric design, and the first lens is aspheric for correcting the axis For the monochromatic aberrations and distortions in the outer field of view, the eighth lens is used to correct the monochromatic aberrations on the axis.

Description

A lens for a digital projector

technical field

The invention relates to a lens, in particular to a lens for a digital projector.

Background technique

With the development of semiconductor technology in recent years, the projection display industry based on technologies such as DLP (Digital Light Processing: Digital Light Processing), LCD (Liquid Crystal Display: Liquid Crystal Display), and LCOS (Liquid Crystalon Silicon: Liquid Crystal on Silicon) has developed rapidly. Over the years, DLP projection display technology has developed rapidly with its rich colors, high-definition images, high-brightness images and high-contrast displays. It can achieve smaller and lighter product features, so DLP (Digital Light Processing : digital light processing) miniature projectors have also obtained rapid development. The core component of DLP (Digital Light Processing: Digital Light Processing) technology mainly adopts DMD (Digital Micromirror Device: Digital Micro Mirror) image chip. DMD (Digital Micro Mirror Device: Digital Micro Mirror) is a digital image exclusively mastered and developed by Texas Instruments. Chip, which is composed of many digital micro-mirrors arranged in a matrix. When working, the micro-mirrors will flip 10 degrees and 12 degrees with the digital signal of the image, and the light beam from the lighting source will enter the projection lens through the flipping of the micro-mirrors. imaged on the screen. In order to match the incident angle of the DMD (Digital Micromirror Device: digital micro-mirror) chip, improve the uniformity of the projection display screen, and rationally arrange the components of the projection equipment, the lighting system mostly uses TIR (total internal reflection: total internal reflection) prisms. Therefore, DLP (Digital Light Processing: Digital light processing) systems are divided into telecentric lighting systems and non-telecentric lighting systems according to different product solutions. This requires a different type of projection lens to match the TIR prism.

For LCOS (LiquidCrystalonSilicon: liquid crystal on silicon) and LCD (LiquidCrystalDisplay: liquid crystal display) projection optical systems, they have a common feature that they need a telecentric beam to illuminate the imaging chip, and of course a projection lens with a telecentric optical path is required. This can better ensure the uniformity of illumination on the image plane. In addition, since DLP (Digital Light Processing: digital light processing), LCOS (Liquid Crystalon Silicon: liquid crystal on silicon) or LCD (Liquid Crystal Display: liquid crystal display) systems will use TIR (total internal reflection: total internal reflection) or PBS (polarization beam splitter polarization beam splitter prism) prism to To achieve effective lighting, therefore, the projection lens needs to retain a long rear working distance when matching it, which greatly increases the difficulty of controlling the length of the lens and off-axis aberration. The measure is generally to increase the number of lenses, generally more than ten pieces As a result, the lens becomes complicated, and when the field of view increases, there will be obvious distortion. Through investigation, it is not difficult to find that some projector lenses on the market generally have shortcomings such as large size, low image quality, and small field of view.

Contents of the invention

In order to solve the above-mentioned defects in the prior art, the present invention provides a wide-angle miniature high-definition projection lens suitable for 0.47inch1080pDMD (digital micromirror chip with a long rear working distance and a telecentric lighting system, the lens increases The field of view is enlarged but the effect of uniform illumination is still achieved, and the relative illumination of the edge is greater than 80%.

The present invention is achieved through the following technical solutions:

A lens for a digital projector, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, The eighth lens and the ninth lens;

An aperture stop is arranged between the fourth lens and the fifth lens, and the aperture stop is close to the fifth lens;

The first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens, the fourth lens is a positive lens, the fifth lens is a positive lens, the sixth lens is a positive lens, the seventh lens is a negative lens, and the fourth lens is a positive lens. The eighth lens is a positive lens and the ninth lens is a positive lens;

The first lens is a meniscus concave lens, the second lens is a meniscus concave lens, the third lens is a biconcave lens, the fourth lens is a biconvex lens, the fifth lens, and the sixth lens are plano-concave lenses, and the seventh lens is a concave lens. The eighth lens is a meniscus concave lens and the ninth lens is a biconvex lens;

The sixth lens and the seventh lens form the doublet lens J1, and the cemented surface of the doublet lens J1 is away from the aperture stop;

The first lens and the eighth lens are all aspheric lenses; the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the ninth lens are all spherical lenses;

The combined focal length of the first lens, the second lens, the third lens and the fourth lens is f _1-4 , and the combined focal length of the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens is f _5-9 ; and 0.75<|f _1-4 /f _5-9 |<0.95.

Further, the lens material of the sixth lens is crown glass, and the lens material of the seventh lens is flint glass.

Further, the lens material of the first lens and the eighth lens is E48R cycloolefin copolymer.

Further, the air interval between the first lens and the second lens is 0.28mm, the air interval between the second lens and the third lens is 5.666mm, and the air interval between the third lens and the fourth lens is 1.636mm , the air gap between the fourth lens and the aperture stop is 10.175 mm, the air gap between the aperture stop diaphragm and the fifth lens is 0.1 mm, and the fifth lens forms a doublet lens J1 with the sixth lens and the seventh lens The air gap between the cemented lenses of the doublet lens J1 is 5.044mm, and the air gap between the cemented lenses of the fifth lens, the sixth lens, and the seventh lens is 0.104mm, and the gap between the eighth lens and the ninth lens is 0.104mm. The air gap between them is 0.1mm.

Beneficial effect:

1. The first lens and the eighth lens close to the screen adopt an aspheric design, in which the first lens is aspheric to correct the monochromatic aberrations and distortions of the off-axis field of view, and the eighth lens is used to correct the on-axis Monochromatic aberrations.

2. The image square telecentric light path is adopted to control the CRA to match the lighting system within a certain range, so as to achieve the effect of good image contrast and high energy utilization rate.

3. The lens has high resolution, the edge resolution reaches the chip limit resolution of 93, and the pixel reaches 2 million ultra-high definition.

4. The lens is small in size and has a large rear working distance, the optical TTL is less than 4.7cm, the outer diameter is less than 24mm, and the rear working distance is greater than 19mm.

5. The lens achieves a wide-angle effect with a field of view greater than 86 degrees, but the distortion is only 2%, and the edge image quality does not decrease.

6. The lens increases the field of view but still achieves the effect of uniform illumination, and the relative illumination at the edge is greater than 80%.

Description of drawings

Accompanying drawing 1 is the lens structure schematic diagram that is used for digital projector;

Accompanying drawing 2 is the transfer function graph that is used for the lens of digital projector;

Accompanying drawing 3 is the field curvature and distortion curve diagram of the lens that is used for digital projector;

Accompanying drawing 4 is the vertical axis chromatic aberration graph of the lens that is used for digital projector;

Accompanying drawing 5 is the energy concentration graph that is used for the lens of digital projector;

The reference signs are as follows:

L1-first lens, L2-second lens; L3-third lens; L4-fourth lens; L5-fifth lens; L6-sixth lens; L7-seventh lens; L8-eighth lens; L9- Ninth lens.

detailed description

Now in conjunction with accompanying drawing 1 to 5, the present invention is further elaborated:

A lens for a digital projector, the projection lens adopts a reverse telephoto optical system scheme, the lens materials of the first lens L1 and the eighth lens L8 are both E48R aspherical lenses, and the first lens L1 is an aspheric lens for correction For various monochromatic aberrations and distortions in the off-axis field of view, the eighth lens L8 is used to correct various on-axis monochromatic aberrations.

In order to ensure the realization of the wide angle and realize the long working distance at the same time, the focal power distribution is as follows, the combined focal length of the first lens L1 to the fourth lens L4 is f _1-4 , the combined focal length of the fifth lens L5 to the ninth lens L9 is f _5-9 , the optical system needs to satisfy the condition: |0.75<f _1-4 /f _5-9 |<0.95, if |f _1-4 /f _5-9 |≥0.95, the system cannot guarantee sufficient For a long back working distance, if |f _1-4 /f _5-9 |≤0.75, the power of the negative group will become too large, resulting in excessive aberration.

After diverging the beams of each field of view through the diverging lens, the projection height of the light increases, and the high-level aberration of the aperture will increase. Therefore, the fourth lens L4 is selected as a positive lens with a high refractive index material to converge the beams. On the one hand It can properly reduce the influence of the advanced aberration of the aperture, and at the same time, it can better ensure the improvement of the uniformity of the image plane.

In order not to make the incident angle of the beam entering the rear group too large, the fourth lens L4 with a biconvex shape is placed near the aperture stop, so that the incident angle of the off-axis beam entering the rear group is appropriately reduced, thereby reducing the high-level The influence of aberration; the cemented lens J1 composed of the sixth lens L6 and the seventh lens L7 in the rear group of the system works in the converging light beam in this system. According to such object-image relationship, the seventh lens L7 of flint glass needs to be Placed on the side of the screen, the direction of the side of the screen is the direction of the image, which is the opposite direction to the object, so that the radius of the glued surface will not be too small when correcting the comprehensive aberration of the system, thereby ensuring the processability of the lens Further improve.

In conjunction with accompanying drawing 1, projector projection lens of the present invention, wherein objective lens is by the first lens L1 that is arranged on the same optical axis, the second lens L2 and the 3rd lens L3, the 4th lens L4, the 5th lens L5, the 5th lens Six lenses L6, seventh lens L7, eighth lens L8, and ninth lens L9. The first lens L1 and the eighth L8 are aspherical, and the projection lens adopts the telecentric structure of the image plane. Table 1 and Table 2 respectively show that the first lens L1 and the eighth L8 are aspherical for the image square telecentric fixed-focus projection lens. Lens parameters; the air space between the first lens L1 and the second lens L2 is 0.28mm, the air space between the second lens L2 and the third lens L3 is 5.666mm, and the air space between the third lens L3 and the fourth lens L4 The air interval between the fourth lens L4 and the aperture stop is 1.636mm, the air interval between the aperture stop diaphragm and the fifth lens L5 is 0.1mm, the air interval between the fifth lens L5 and the sixth lens The air gap between the cemented lenses of the doublet lens J1 composed of L6 and the seventh lens L7 is 5.044 mm, and the fifth lens L5, the sixth lens L6 and the seventh lens L7 form the gap between the cemented lenses of the doublet lens J1 and the eighth lens L8 The air space between the eighth lens L8 and the ninth lens L9 is 0.1 mm.

The aspheric formula is as follows:

Table 1 is the lens parameters of the first lens

Table 2 is the lens parameters of the eighth lens

The parameters of the front and rear surfaces and the aspheric parameters in Tables 1 and 2 satisfy this formula.

The described embodiment is a preferred implementation of the present invention, but the present invention is not limited to the above-mentioned implementation, without departing from the essence of the present invention, any obvious improvement, replacement or modification that those skilled in the art can make Modifications all belong to the protection scope of the present invention.

Claims (4)

1. the camera lens for digital projector, it is characterized in that, be followed successively by the first lens (L1), the second lens (L2), the 3rd lens (L3), the 4th lens (L4), the 5th lens (L5), the 6th lens (L6), the 7th lens (L7), the 8th lens (L8) and the 9th lens (L9) including along optical axis from object plane to image planes;

It is provided with aperture diaphragm between described 4th lens (L4) and the 5th lens (L5), and aperture diaphragm is near the 5th lens (L5);

Described first lens (L1) are plus lens, the second lens (L2) are minus lens, the 3rd lens (L3) plus lens, the 4th lens (L4) are plus lens, the 5th lens (L5) plus lens, the 6th lens (L6) are plus lens, the 7th lens (L7) are minus lens, the 8th lens (L8) are plus lens for plus lens and the 9th lens (L9);

Described first lens (L1) are falcate concavees lens, second lens (L2) are falcate concavees lens, the 3rd lens (L3) are biconcave lens, the 4th lens (L4) biconvex lens, the 5th lens (L5), the 6th lens (L6) are planoconcave lens, and the 7th lens (L7) are concavees lens, the 8th lens (L8) are biconvex lens for falcate concavees lens and the 9th lens (L9);

6th lens (L6) and the 7th lens (L7) form cemented doublet J1, and the cemented surface of cemented doublet J1 deviates from aperture diaphragm;

Described first lens (L1) and the 8th lens (L8) are non-spherical lens; Described second lens (L2), the 3rd lens (L3), the 4th lens (L4), the 5th lens (L5), the 6th lens (L6), the 7th lens (L7) and the 9th lens (L9) are spherical lens;

The combined focal length of described first lens (L1), the second lens (L2), the 3rd lens (L3) and the 4th lens (L4) is f_1-4, the combined focal length of the 5th lens (L5), the 6th lens (L6), the 7th lens (L7), the 8th lens (L8) and the 9th lens (L9) is f_5-9; And 0.75 < | f_1-4/f_5-9|<0.95��

2. the camera lens for digital projector according to claim 1, it is characterised in that described 6th lens (L6) lens material is crown glass, and the 7th lens (L7) lens material is flint glass.

3. the camera lens for digital projector according to claim 1, it is characterised in that described first lens (L1) and the 8th lens (L8) lens material are E48R cyclic olefine copolymer.

4. the camera lens for digital projector according to claim 1, it is characterized in that, airspace between first lens (L1) and the second lens (L2) is 0.28mm, airspace between second lens (L2) and the 3rd lens (L3) is 5.666mm, airspace between 3rd lens (L3) and the 4th lens (L4) is 1.636mm, airspace between 4th lens (L4) and aperture diaphragm is 10.175mm, between aperture diaphragm light hurdle and the 5th lens (L5), airspace is 0.1mm, it is 5.044mm that 5th lens (L5) and the 6th lens (L6) and the 7th lens (L7) form airspace between the cemented doublet of cemented doublet J1, it is 0.104mm that 5th lens (L5) and the 6th lens (L6) and the 7th lens (L7) form airspace between the cemented doublet of cemented doublet J1 and the 8th lens (L8), between 8th lens (L8) and the 9th lens (L9), airspace is 0.1mm.