TWI711837B - Imaging lens device - Google Patents

Abstract

The present application relates to an imaging lens device applied between an object plane and an image plane.  It includes: a first lens set located near the image plane and having a negative refractive index, the first lens set including a negative aspherical lens whose cross section is a circle which is cut off at the top and the bottom; and a second lens set located near the object plane and having a positive refractive index.  The relative distance between the second lens set and the first lens set is fixed.  The object plane is a preset offset below the axis of the second lens set, and an image is formed on the image plane above the axis of the first lens set.

Description

Imaging lens device

This case is an imaging lens device, especially an imaging lens device that can be applied to a projection device.

From notebook computers and tablet computers to smart phones, the size of portable information devices is shrinking day by day, and the size of the display is also shrinking, so it is not suitable for presentations, and projectors are commonly used in such occasions. Device. However, conventional projectors are too large and heavy to carry. As a result, some companies have reduced the size and weight of the projector, and even integrated it into a smart phone or other portable devices.

The use environment of such miniaturized projectors is usually very close to the projection wall, so the concept of short-throw projectors was developed to break through these limitations. It can project larger ones at a closer distance. The image, and the light exposure distance of this type of projector will not be too long, so the brightness does not need to be too bright, which is conducive to energy saving and environmental protection, and reduces subsequent maintenance costs. However, this type of miniaturized projector still has the obstacles that its size is not easy to shrink and the projection height is not enough to break through. Therefore, technical means that can improve the conventional technical obstacles have been developed.

This case is mainly an imaging lens device, which is applied between an object plane and an image plane, and includes: a first lens group close to the image plane, which has a negative refractive index, and the first lens group includes a negative focal length The aspheric lens; a second lens group close to the object surface and has a positive refractive index, the second lens group includes an aspheric lens with a positive focal length and the second lens group and the first lens group are opposite The distance is fixed, and the focal length f1 of the first lens group and the focal length f2 of the second lens group satisfy 1.03<|f2/f1|<1.43.

According to the above-mentioned conception, in the imaging lens device of the present application, the object surface to which it is applied can be a silicon-based liquid crystal module in a projector, and the image surface can be a projection surface.

According to the above conception, in the imaging lens device of the present application, the second lens group further includes four spherical lenses, and the aspheric lens with a positive focal length is closest to the object surface.

According to the above conception, in the imaging lens device of the present application, the material of the aspheric lens with negative focal length and the aspheric lens with positive focal length is plastic E48R.

According to the above conception, in the imaging lens device of the present application, the object plane is set at a predetermined offset distance below the central axis of the second lens group, and the image is formed on the image plane above the central axis of the first lens group .

According to the above-mentioned conception, in the imaging lens device of the present application, the cross-section of the negative focal length aspheric lens is formed by a circular upper and lower cut, and the width of the top after the upper half is cut is 20/29 of the diameter of the circle , The bottom width after the lower half is cut is 16.28/29 of the diameter of the circle.

Another aspect of the present case is an imaging lens device, applied between an object plane and an image plane, which includes: a first lens group close to the image surface, which has a negative refractive index; a second lens group close to the object The surface has a positive refractive index, the relative distance between the second lens group and the first lens group is fixed, and the object surface is located at a predetermined offset distance below the central axis of the second lens group, and the image is imaged on the first lens group. The image plane above the central axis of a lens group.

Another aspect of this case is an imaging lens device, which is applied between an object plane and an image plane, and includes: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes a Aspheric lens with negative focal length, the cross-section of the aspheric lens with negative focal length is formed by cutting the upper and lower parts of a circle. The width of the top after the upper half is cut is 20/29 of the diameter of the circle. After the lower half is cut off The bottom width of the circle is 16.28/29 of the circular diameter; and the second lens group is close to the object surface and has a positive refractive index, and the relative distance between the second lens group and the first lens group is fixed.

Another aspect of this case is an imaging lens device, applied between an object plane and an image plane, which includes: a first lens group close to the image plane, which has a negative refractive index, and the first lens group includes a negative Aspherical lens with focal length, the cross-section of the aspheric lens with negative focal length is formed by cutting the upper and lower parts of a circle. The width of the top after the upper half is cut is 20/29 of the diameter of the circle, and the lower half is cut off The bottom width is 16.28/29 of the circular diameter; and the second lens group is close to the object surface and has a positive refractive index. The relative distance between the second lens group and the first lens group is fixed, and the first lens The focal length f1 of the second lens group and the focal length f2 of the second lens group satisfy 1.03＜│f2/f1│＜1.43, and the object plane is located at a predetermined offset distance below the central axis of the second lens group, and the image is formed on the first lens group. The image plane above the central axis of a lens group.

The last aspect of this case is an imaging lens device, applied between an object plane and an image plane, which includes: a first lens group close to the image plane, which has a negative refractive index, and the first lens group includes a negative Aspherical lens with a focal length, the cross-section of the aspheric lens with a negative focal length is formed by cutting a circular upper and lower part; and a second lens group close to the object surface and having a positive refractive index, the second lens group and the first lens group The relative distance between a lens group is fixed, and the object plane is located at a predetermined offset distance below the central axis of the second lens group, and the image is formed on the image plane above the central axis of the first lens group.

Some typical embodiments that can realize the features and advantages of this case will be described in detail in the following description. It should be understood that this case can have various changes in different aspects, which do not deviate from the scope of the patent application of this case, and the descriptions and drawings therein are essentially for illustrative purposes, not to limit the case .

Please refer to Figure 1, which is a schematic diagram of the optical path structure of the micro-projector proposed by the present invention, in which the light source module 10 is capable of emitting a mixture of red, green and blue three primary colors (in this example, a three-color light-emitting diode (LED) light source) The non-single polarized light produced) means that it is a common light source that can emit two types of light mixed with "P-polarized light" and "S-polarized light". The "P polarized light" and "S polarized light" are processed by the array lens 11 to homogenize the light and energy, and then sent to the Polarization Conversion System (PCS) 12 for conversion to The light originally mixed with P-polarized light and S-polarized light is converted into a single polarized light as much as possible (in this case, the conversion into S-polarized light is used as an example) and then transmitted on a transmission path. The light output from the polarization converter 12 is collected by a condenser lens (Condenser len) 13, and then sent to a Polarization Beam. Splitting Prism (PBS) 14 for processing.

However, in order to simplify the polarization of the light, in this case, a polarizer 149 is provided before the incident surface 140 of the polarized light separation beam 14. This polarizer 149 is completed by a reflective polarizer to allow the first polarization type The light travels along a first path, and the second polarization type light travels toward the reflected second path. In this example, the first polarization type light and the second polarization type light are the above-mentioned S-polarized light and P-polarized light. As for the polarization separation beam 14 to receive the first polarization type light (S-polarized light in this example) along the first path (transmitted through the polarizer 149) and guide it to a third path (the figure is reflected to On the right), the silicon-based liquid crystal module 15 including a retarder 150 receives the first polarization type light (S-polarized light in this example) along the third path, modulates the light and reflects it The second polarization type light (P-polarized light in this example) carrying an image is converted into the polarized light splitting beam 14 and then sent to the imaging lens device 16, and the imaging lens device 16 receives the polarized light splitting beam. The second polarization type light (P-polarized light in this example) is focused and imaged.

係數列表如下：其中S1與S2是透鏡161兩個表面的曲線參數，S1是靠近投影表面S0的表面，而S2是遠離投影表面S0的表面。至於S7是孔徑光柵欄結構。投影表面S0可簡稱像面，而矽基液晶模組15則可簡稱物面S14。

For a schematic diagram of a preferred embodiment of the imaging lens device 16 in this case, please refer to FIG. 2. It is mainly composed of six lenses 161 to 166. The lens 161 and the lens 166 are aspherical lenses, and the lens 162, the lens 163, and the lens 164 are The lens 165 is a spherical lens. In order to make the aspheric lens easy to manufacture, the material of the lens 161 and the lens 166 can be plastic E48R. Instead of the spherical formula:

The coefficient list is as follows: where S1 and S2 are the curve parameters of the two surfaces of the lens 161, S1 is the surface close to the projection surface S0, and S2 is the surface away from the projection surface S0. As for S7 is the aperture grating column structure. The projection surface S0 can be referred to as the image plane, and the silicon-based liquid crystal module 15 can be referred to as the object plane S14.

The material of the lens 162, the lens 163, the lens 164, and the lens 165 may be glass. In the arrangement of lens types, lens 161, lens 162, lens 164, and lens 165 are divergent lenses with negative focal length, lens 163 and lens 166 are focusing lenses with positive focal length, and lens 161 itself forms a negative refractive index. As for the first lens group of lens 162, lens 163, lens 164, lens 165 and lens 166, a second lens group with a positive refractive index is formed. The first lens group is close to the end of the projection surface, and the second lens group is close to the end of the silicon-based liquid crystal module 15. This lens group is a fixed focus projection lens group, and the distance between the two groups of lenses is fixed. When the distance between the imaging lens device 16 and the projection surface changes, by adjusting the distance between the second lens group and the end of the silicon-based liquid crystal module 15, the image can be made clear. When the imaging lens device 16 of this case satisfies the following conditions, 1.03＜│f2/f1│＜1.43, where f1 and f2 are the focal lengths of the first lens group and the second lens group respectively, which can make the image quality reach a better state . The specifications of each lens in the imaging lens device 16 are as shown in the following table. Among them, the Abbe number is a physical parameter invented by German physicist Ernst Abbe, also called "V-number", which is used to measure the degree of light dispersion of the medium. The greater the degree of light dispersion, the lower the Abbe number, and the smaller the degree of light dispersion, the greater the Abbe number. Furthermore, if the absolute value of the focal length ratio of the first lens group and the second lens group is made to fall within the range of 1.21<│f2/f1│<1.25, the picture quality will be better.

Refer to Figure 2 again, in order to make the projected screen of this case achieve the effect of screen displacement as shown in the figure, that is, to shift the projected screen to a height above the horizontal line, so that the user can project to a high place on the desktop. The lens 161 and the lens 166 completed by the spherical lens play an important role. The schematic diagram of the light path can be seen in Fig. 2. The object plane S14 is located below the central axis 40, and the light source offset is 2.3 mm. It can be clearly seen from the figure that the light passes through the lenses in this case and then returns to the image on the projection surface S0 above the central axis 40. This is mainly the effect achieved by the lens 161 and the lens 166 completed by the aspheric lens. In this way, this case can achieve the effect of shifting the projection screen by a height above the horizontal line, and then achieve the purpose of shifting the position of the projection screen.

Please refer to FIG. 3 again, which is a three-dimensional exploded schematic diagram of the assembly of the above six lenses, which shows the exploded state of the six lenses 161 to 166 and the related assembly support structure assembly 169. Among them, the lens 161 completed by the aspheric lens adopts a special-shaped design, which reduces the invalid part and cuts off the upper and lower parts of the original circular lens (diameter is 29 mm). The top width TW after the upper half is cut is 20mm. The bottom width BW after the lower half is cut off is 16.28mm. The main purpose is to remove the 6.5 mm lens height to reduce the total lens height to 22.5 mm, and to reduce the thickness of the completed optomechanical module. In the lens group completed in this way, the throw ratio of the entire lens group is less than or equal to 0.8, and the aperture F=46.4/29=1.6 (46.4 refers to the focal length of the lens), which can effectively increase the luminous flux. Therefore, the preferred cutting ratio for lens height reduction in this case is: the top width after the upper half is cut is 20/29 of the diameter of the circle, and the bottom width after the lower half is cut is 16.28/29 of the diameter of the circle.

As for Figure 4, a cross-sectional view of the actual assembly of the six lenses 161~166 is shown, which shows their size and the distance between each other. It can be clearly seen that the maximum height of the lens group is only 22.5 mm. The depth is only 51.52mm, so it can effectively achieve the purpose of size reduction.

This case can be applied to mini projectors or other similar handheld electronic devices, such as mobile phones, personal digital assistants (PDAs), tablet computers, digital cameras, Digital video camera, portable multimedia device or other suitable handheld device. The above-mentioned device can improve the thickness and projection angle of the projector. Moreover, the device proposed in this case is very suitable for miniaturized portable electronic devices, thereby achieving the effect of improving conventional technologies.

In summary, in the present invention, although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field, without departing from the spirit and scope of the present invention, While some changes and modifications can be made, the protection scope of the present invention shall be subject to the scope of the attached patent application.

10‧‧‧Light source module 11‧‧‧Array lens 12‧‧‧Polarization converter 13‧‧‧Condenser lens 14‧‧‧ Polarized light separation beam 15‧‧‧Si-based LCD module 16‧‧‧Imaging lens device 40‧‧‧Central axis 140‧‧‧ incident surface 149‧‧‧Polarizer 150‧‧‧Phase retarder 161~166‧‧‧Lens 169‧‧‧Assemble support structure assembly S0‧‧‧Projection surface S1~S6, S8~S13‧‧‧Lens surface S7‧‧‧Aperture grating column structure S14‧‧‧Object BW‧‧‧Bottom width TW‧‧‧Top width

Fig. 1 is a schematic diagram of the optical path structure of the micro-projector proposed by the present invention. Figure 2 is a schematic diagram of the lens combination of the imaging lens device developed in this case. Fig. 3 is a three-dimensional exploded schematic diagram of the assembly of six lenses in the imaging lens device. Fig. 4 is a schematic diagram showing the cross-sectional dimensions of the actual assembly of six lenses.

no

40‧‧‧Central axis

161~166‧‧‧Lens

S0‧‧‧Projection surface

S1~S6, S8~S13‧‧‧Lens surface

S7‧‧‧Aperture grating column structure

S14‧‧‧Object

Claims (10)

An imaging lens device, applied between an object surface and an image surface, comprising: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes an aspheric surface with a negative focal length Lens; a second lens group close to the object surface and having a positive refractive index, the second lens group includes an aspheric lens with a positive focal length and the relative distance between the second lens group and the first lens group is fixed, The focal length f1 of the first lens group and the focal length f2 of the second lens group satisfy 1.03<|f2/f1|<1.43. As for the imaging lens device described in item 1 of the scope of patent application, the object surface to which it is applied is a silicon-based liquid crystal module in a projector, and the image surface is a projection surface. In the imaging lens device described in claim 1, wherein the second lens group further includes four spherical lenses, and the aspheric lens with a positive focal length is closest to the object surface. The imaging lens device described in the first item of the scope of patent application, wherein the material of the negative focal length aspheric lens and the positive focal length aspheric lens is plastic E48R. According to the imaging lens device described in claim 1, wherein the object plane is set at a predetermined offset distance below the central axis of the second lens group, and forms the image above the central axis of the first lens group Surface. The imaging lens device described in the first item of the scope of patent application, wherein the cross-section of the aspheric lens with negative focal length is formed by a circular upper and lower cut, and the width of the top after the upper half is cut is 20 of the diameter of the circle. /29, the bottom width after the lower half is cut is 16.28/29 of the diameter of the circle. An imaging lens device, applied between an object surface and an image surface, comprising: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes an aspheric lens with a negative focal length ； A second lens group is close to the object surface and has a positive refractive index, the relative distance between the second lens group and the first lens group is fixed, and the object surface is located below the central axis of the second lens group by a preset Offset distance, and image on the image plane above the central axis of the first lens group. An imaging lens device, applied between an object surface and an image surface, comprising: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes an aspheric lens with a negative focal length , The cross-section of the negative focal length aspheric lens is formed by a circular upper and lower cut, the top width after the upper half is cut is 20/29 of the diameter of the circle, and the bottom width after the lower half is cut is the circle The second lens group is close to the object surface and has a positive refractive index, and the relative distance between the second lens group and the first lens group is fixed. An imaging lens device, applied between an object surface and an image surface, comprising: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes an aspheric lens with a negative focal length , The cross-section of the negative focal length aspheric lens is formed by a circular upper and lower cut, the top width after the upper half is cut is 20/29 of the diameter of the circle, and the bottom width after the lower half is cut is the circle And a second lens group close to the object surface and having a positive refractive index, the relative distance between the second lens group and the first lens group is fixed, and the focal length f1 of the first lens group The focal length f2 with the second lens group satisfies 1.03<|f2/f1|<1.43, and the object plane is located at a predetermined offset distance below the central axis of the second lens group, and the image is formed on the central axis of the first lens group The image surface above the line. An imaging lens device, applied between an object surface and an image surface, comprising: a first lens group close to the image surface, which has a negative refractive index, and the first lens group includes an aspheric lens with a negative focal length , The cross-section of the negative focal length aspheric lens is formed by cutting the upper and lower parts of a circle; and A second lens group is close to the object surface and has a positive refractive index, the relative distance between the second lens group and the first lens group is fixed, and the object surface is located below the central axis of the second lens group by a preset Offset distance, and image on the image plane above the central axis of the first lens group.

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