Optomechanical structure with multifocal lens

Abstract

The present invention relates to a multifocal lens and a mold and an optical-mechanical structure for manufacturing the multifocal lens. A lens comprises a first curved surface and a second curved surface. The first curved surface and the second curved surface have different focal lengths and are arranged alternately in the radial direction of the lens.

Description

Technical Field

[0001] The present invention relates to a lens, and more particularly to a multifocal lens with an extendable operable depth of field, a mold for making the multifocal lens, and an optical-mechanical structure using the multifocal lens. Background Art

[0002] It's known that a lens's depth of field (DOF) is determined by the object distance and the aperture (F number). Shorter object distances result in shorter DOF. In applications with short working object distances, a very short DOF requires tight assembly tolerances; otherwise, assembly deviations can easily cause light to converge outside the lens' DOF. For example, the current standard DOF for optical mice is approximately 2.4 ± 0.2 mm. Excessive assembly tolerances can blur the image captured by the optical sensor, reducing operational accuracy.

[0003] Although it is known that the depth of field of a lens can be increased through extended depth of field (EDOF), current EDOF is mainly achieved through software post-processing, rather than the lens itself having the ability to extend the depth of field.

[0004] In view of this, the present invention provides a multifocal lens that can effectively extend the depth of field of the lens, a mold for manufacturing the multifocal lens, and an optomechanical structure using the multifocal lens. Summary of the Invention

[0005] The present invention provides a lens with multiple focal lengths, wherein curved surfaces with different focal lengths are arranged in a staggered manner in the radial direction of the lens, and the focal points of the different focal lengths converge on the same optical axis of the lens.

[0006] The present invention also provides a mold for making a multifocal lens. The mold is engraved with mold surfaces of different curvatures arranged alternately on the inner surface of the mold to produce curved surfaces of different focal lengths of the multifocal lens.

[0007] The present invention also provides an optical machine including a multifocal lens, which has an extended depth of field and is suitable for an optical tracking device with a long working distance.

[0008] The present invention provides a lens comprising an incident surface, a first curved surface, and a second curved surface. The first curved surface has a first focal length. The second curved surface has a second focal length. The first curved surface and the second curved surface are arranged alternately on the incident surface in a radial direction of the lens.

[0009] The present invention also provides a mold for making a multifocal lens, comprising an inner surface and a ring wall. The inner surface comprises a first mold surface and a second mold surface, each used to shape the first curved surface and the second curved surface of the mold, respectively, for shaping the lens. The ring wall extends from the periphery of the inner surface.

[0010] The present invention also provides an optomechanical structure comprising a light source, a multifocal lens, and a light sensor. The light source is configured to project light toward a work surface to generate reflected light. The multifocal lens comprises a first curved surface having a first focal length and a second curved surface having a second focal length, wherein the first curved surface and the second curved surface are arranged alternately in a radial direction of the lens on an incident surface of the lens. The light sensor is configured to receive the reflected light through the multifocal lens.

[0011] In order to make the above and other purposes, features and advantages of the present invention more apparent, the following will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, the same components are represented by the same symbols and are hereby combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a stereoscopic diagram of a multifocal lens according to an embodiment of the present invention;

[0013] Figure 2 is a cross-sectional view of a multifocal lens according to an embodiment of the present invention;

[0014] Figure 3 The embodiment of the present invention is used to make Figure 1 and Figure 2 A cross-sectional view of a mold of a multifocal lens;

[0015] Figure 4 Schematic diagram of the operation of a multifocal lens in combination with a monochromatic light source according to an embodiment of the present invention;

[0016] Figure 5 Schematic diagram of the operation of a multi-focal lens in combination with a dual-color light source according to an embodiment of the present invention;

[0017] Figure 6A The use of the embodiment of the present invention Figure 1 and Figure 2 Exploded diagram of the optical mechanism of the multifocal lens;

[0018] Figure 6B The use of the embodiment of the present invention Figure 1 and Figure 2 A cross-sectional view of an optical machine of a multifocal lens; Figures 7A-7B is a schematic diagram of the operation of an optical mouse using a multifocal lens according to an embodiment of the present invention; and

[0019] Figure 8 The use of the embodiment of the present invention Figure 1 and Figure 2 Another cross-sectional view of the optical machine of the multifocal lens.

[0020] Description of Reference Numerals

[0021] 100 lenses

[0022] 100S incident surface

[0023] 100E exit surface

[0024] 101 First Surface

[0025] 103 Second Surface

[0026] 300 mold

[0027] f1, f2 focus

[0028] DOF1, DOF2 Depth of Field DETAILED DESCRIPTION

[0029] The present invention provides a lens with multiple focal lengths, which has an extended operational depth of field and is suitable for applications with short object distances, such as, but not limited to, optical mice and optical hair removers. Consequently, optical devices utilizing the multifocal lens of the present invention can have a longer working distance. The present invention also provides a mold for manufacturing the multifocal lens.

[0030] Please refer to Figure 1 and Figure 2 As shown, Figure 1 is a three-dimensional diagram of a lens 100 according to an embodiment of the present invention; Figure 2 1 is a cross-sectional view of a lens 100 according to an embodiment of the present invention. Lens 100 comprises an incident surface 100S, a first curved surface 101, and a second curved surface 103. In one embodiment, first curved surface 101 and second curved surface 103 are arranged alternately on incident surface 100S in a radial direction of lens 100. Lens 100 further comprises an exit surface 100E opposite incident surface 100S. In one embodiment, exit surface 100E is a plane.

[0031] In one embodiment, the first curved surface 101 is located on the first spherical surface and the second curved surface 103 is located on the second spherical surface. Figure 2 As shown, the first spherical surface and the second spherical surface have different radii.

[0032] The first curved surface 101 has a first focal length (eg Figure 4 ) and the second curved surface 103 has a second focal length (e.g. Figure 4 The first focus f1 and the second focus f2 are located on the same optical axis 100 of the lens 100. AX On the optical axis 100 AX For example, through the center of the lens 100. In the present invention, the first focal length and the second focal length are focal lengths relative to light of the same color (such as infrared light, blue light, or ultraviolet light, but not limited thereto).

[0033] In order to converge the near-field light and the far-field light at the focal points f1 and f2, the first curved surface 101 includes at least two first curved surface rings, for example Figure 1 and Figure 2 Two first curved surface rings and a central curved surface are shown; and the second curved surface 103 includes at least two second curved surface rings, such as Figure 1 and Figure 2 The three secondary surface rings are displayed.

[0034] It must be pointed out that although Figure 1 and Figure 2 In the illustrated embodiment, the first curved surface 101 is disposed at the center of the incident surface 100S, and the second curved surface 103 (i.e., the second curved surface ring) surrounds the first curved surface 101 (or the central curved surface) at the center of the incident surface 100S. However, the present invention is not limited to this embodiment. In other embodiments, the second curved surface 103 is disposed at the center of the incident surface 100S, and the first curved surface 101 (i.e., the first curved surface ring) surrounds the second curved surface 103 at the center of the incident surface 100S.

[0035] In one embodiment, the lens 100 of the embodiment of the present invention is made of plastic or glass, for example, and is formed by injection molding.

[0036] Please refer to Figure 3 As shown, it is used to make Figure 1 and Figure 2 A cross-sectional view of a mold 300 for lens 100 is shown. Mold 300 includes an inner surface (or bottom surface) 300S and sidewalls 300W. Sidewalls 300W extend from the periphery of inner surface 300S, either vertically or at an angle. When the material used to make lens 100 is injected into mold 300 and demolded, the lens 100 of the present invention is formed.

[0037] Since the inner surface 300S is used to form the incident surface 100S of the lens 100 , the inner surface 300S includes a first mold surface 301 and a second mold surface 303 for shaping the first curved surface 101 and the second curved surface 103 of the lens 100 , respectively.

[0038] Relative to the incident surface 100S of the lens 100 , the first mold surface 301 includes at least two first annular structures having a first curvature, for example Figure 3 Two first annular structures and a central curved structure are shown; and the second mold surface 303 includes at least two second annular structures having a second curvature, such as Figure 3 Three second annular structures are shown, wherein the second curvature is different from the first curvature.

[0039] It must be pointed out that although Figure 3In the illustrated embodiment, the first mold surface 301 is disposed at the center of the inner surface 300S, and the second mold surface 303 surrounds the first mold surface 301 at the center of the inner surface 300S (or referred to as a central curved surface structure), but the present invention is not limited thereto. In other embodiments, the second mold surface 303 is disposed at the center of the inner surface 300S, and the first mold surface 301 surrounds the second mold surface 303 at the center of the inner surface 300S.

[0040] Relative to the incident surface 100S of the lens 100 , the at least two first annular structures are located on a first spherical surface and the at least two second annular structures are located on a second spherical surface, wherein the first spherical surface and the second spherical surface have different radii.

[0041] Please refer to Figure 4 As shown, it shows a schematic diagram of the operation of monochromatic light passing through the lens 100. Figure 4 In FIG. 1 , the first depth of field of the first curved surface 101 is shown as DOF1 and the second depth of field of the second curved surface 103 is shown as DOF2. In one embodiment, the first depth of field DOF1 of the first curved surface 101 is between 2 mm and 5 mm and the second depth of field DOF2 of the second curved surface 103 is between 5 mm and 10 mm. Figure 6B Component 63 and Figure 8 element 83) at a distance from the center of the lens 100 (e.g. Figure 4 Images containing identifiable features can be acquired between 2 mm and 10 mm from the position 0 shown. The lens 100 can be applied to optical tracking devices, such as optical mice and optical hair removers.

[0042] like Figure 4 As shown, the first depth of field DOF1 of the first curved surface 101 and the second depth of field DOF2 of the second curved surface 103 can be in the optical axis direction of the lens 100 (eg 100 AX For example, the first curvature of the first curved surface 101 and the second curvature of the second curved surface 103 are configured so that the first curved surface 101 generates three times the first minimum circle of confusion CC1 (for example Figure 4 The first minimum circle of confusion is at the focus point f1 and the triple first minimum circle of confusion is at the positions X1 and X2 , which is generated by the triple second minimum circle of confusion CC2 (e.g. Figure 4 The second smallest circle of confusion is shown at focus f2 and the triple second smallest circle of confusion is at positions X2 and X3). It must be noted that although Figure 4 It is shown that three times the first circle of least confusion CC1 and three times the second circle of least confusion CC2 overlap at position X2 , but the present invention is not limited thereto.

[0043] In other embodiments, three times the first circle of least confusion CC1 may be within the range of the second depth of field DOF2, and three times the second circle of least confusion CC2 may be within the range of the first depth of field DOF1. Although in this configuration, the image captured by the optical sensor will contain ghosting, it will not cause the optical tracking device to fail to operate as long as the processor of the optical tracking device (e.g. Figure 7A and Figure 7B The method shown in 75) can obtain the feature points in the image captured by the optical sensor of the optical tracking device. The method in which the processor tracks the feature points in the image is well known and will not be described in detail here.

[0044] It must be pointed out that although Figure 4 , the focal length of the first curved surface 101 is shorter and the focal length of the second curved surface 103 is longer, but the present invention is not limited thereto. In other embodiments, the focal length of the first curved surface 101 can be longer and the focal length of the second curved surface 103 can be shorter by simply changing the curvature of the first curved surface 101 and the second curved surface 103.

[0045] Please refer to Figure 6A and Figure 6B , which is a schematic diagram of an optomechanical structure 600 using the lens 100 according to an embodiment of the present invention. Figure 6A An exploded view of the opto-mechanical structure 600 is shown. Figure 6B A cross-sectional view of an opto-mechanical structure 600 is shown. The opto-mechanical structure 600 includes a light source 61, a light sensor (shown as a chip) 63, a light-transmitting element 65, and a light-blocking element 67. The light source 61 and the light sensor 63 are disposed on and electrically connected to a substrate.

[0046] The light source 61 is, for example, a light emitting diode (LED) or a laser diode (LD), and is not particularly limited. The light source 61 is used to direct light toward a work surface (e.g. Figure 7A and Figure 7B The WS) shown projects light EL to generate reflected light RL.

[0047] When the light source 61 is a monochromatic light source, it will form Figure 4 When the light source 61 is a two-color light source, for example, the wavelength of the emitted light can be changed by changing its driving parameters or configuring two grains of different color light, which will form Figure 5 The first depth of field DOF1 and the second depth of field DOF2 (relative to the first color light, such as ultraviolet light, but not limited to) and the third depth of field DOF1' and the fourth depth of field DOF2' (relative to the second color light, such as infrared light, but not limited to) are shown. Thus, by changing the wavelength of the light emitted by the light source 61, the distance of each depth of field relative to the multifocal lens 100 can be changed, thereby further expanding the operational depth of field.

[0048] It must be pointed out that although Figure 5 It shows that the third depth of field DOF1' and the fourth depth of field DOF2' are not located on the optical axis 100 AX When the incident light of the lens 100 is parallel light, the third depth of field DOF1' and the fourth depth of field DOF2' are offset along the optical axis direction of the first depth of field DOF1 and the second depth of field DOF2, for example Figure 5 horizontal direction.

[0049] In this embodiment, DOF1 and DOF1 ′ are depths of field of the first curved surface with respect to different wavelengths of light, and DOF2 and DOF2 ′ are depths of field of the second curved surface with respect to different wavelengths of light.

[0050] The present invention can be applied to optical tracking devices with different working distances by configuring a multi-focal lens 100. For example, Figure 7A and Figure 7B The optical-mechanical structure 600 (eg, including the light source 71 and the light sensor 73 ) is shown to be applied to an optical mouse 700 with two operating modes. Figure 7A When the display optical mouse 700 is operated with the first surface DS1 , the working surface WS is located at the first focus f1 of the lens 100 , for example; Figure 7B When the display optical mouse 700 operates on the second surface DS2, the working surface WS is located at the second focus f2 of the lens 100. The reflected light RL from the working surface WS travels through a different optical path before passing through the lens 100 and being received by the optical sensor 73 (eg, the same as the optical sensor 63).

[0051] The optical sensor 63 is, for example, a CMOS image sensor or a CCD image sensor, without particular limitation. The optical sensor 63 is configured to receive the reflected light RL through the multi-focal lens (ie, the lens 100 ).

[0052] Please refer to Figure 6B As shown, the light blocking member 67 is made of an opaque material (for example, by injection molding, but not limited to), and includes a first receiving space 671, a second receiving space 673 and a light blocking wall 675. The first receiving space 671 is used to accommodate the light source 61 and has an opening (such as Figure 6A As shown in FIG1 , the light EL is emitted from the light blocking member 67. The second receiving space 673 is used to receive the light sensor 63 and has an opening as shown in FIG1 . Figure 6A The light blocking wall 675 extends from the light blocking member 67 (e.g., vertically or at an angle) and is located between the first accommodating space 671 and the second accommodating space 673 to block the light directly transmitted from the light source 61 to the light sensor 63.

[0053] The light-transmitting member 65 is made of a light-transmitting material (e.g., by injection molding, but not limited thereto), and includes a first lens structure 651 and a second lens structure 653. The first lens structure 651 is disposed above the light source 61 and has a first optical axis OAX1. The second lens structure 653 is disposed above the light sensor 63 and has a second optical axis OAX2. In one embodiment, the light source 61 and the light sensor 63 are arranged along a first direction (e.g., Figure 6B In the first direction (in the left and right directions), the first optical axis OAX1 is offset from the first centerline CL1 of the light source 61 toward the optical sensor 63, and the second optical axis OAX2 is offset from the second centerline CL2 of the optical sensor 63 toward the light source 61. In this manner, the lateral distance between the light source 61 and the optical sensor 63 can be shortened, thereby facilitating miniaturization of the opto-mechanical structure 600.

[0054] In one embodiment, the multifocal lens 100 is aligned with the second lens structure 653 , and the multifocal lens 100 and the second lens structure 653 are integrally formed on the light-transmitting member 65 .

[0055] Please refer to Figure 8 FIG. 2 shows an optomechanical structure 800 according to another embodiment of the present invention, which is applied to an optical hair remover, for example. The optomechanical structure 800 includes a light source 81 , a light sensor 83 , a multi-focal lens 100 , a carrier 87 , and a substrate 89 .

[0056] The substrate 89 is, for example, a printed circuit board (PCB) or a flexible substrate. The carrier 87 is, for example, formed of an opaque material (e.g., by injection molding, but not limited thereto) and is disposed (e.g., fixed by adhesive or fasteners) on the substrate 89. The carrier 87 has, for example, a housing space for accommodating the light source 81 and the light sensor 83, which are respectively the same as Figure 6B The light source 61 and the light sensor 63 are not described in detail here.

[0057] Although Figure 8 The light source 81 is shown as being tilted, which is for illustration only and is not intended to limit the present invention. In other embodiments, the light source 81 may be vertically disposed relative to the substrate 89 .

[0058] The carrier 87 may further include a carrying space for placing and fixing the lens 100. Since the optical hair remover may be operated by the user at different working distances during operation, the lens 100 of the embodiment of the present invention may be used to effectively enhance the tracking effect.

[0059] It must be noted that the lens 100 of the embodiment of the present invention is not limited to applications in optical mice and optical hair removers. Any optical device that needs to operate at different working distances during operation can be equipped with the lens 100 of the embodiment of the present invention to improve its working efficiency.

[0060] It should be noted that although the lens 100 in the above embodiment is described with two different curved surfaces as an example, the present invention is not limited thereto. The multifocal lens in the embodiment of the present invention can be formed by more than two curved surfaces and have more than two focal points.

[0061] It must be noted that the numerical values ​​in the description of the present invention, such as the depth of field, the number of curved rings, etc., and the spatial relationship of components are merely examples and are not intended to limit the present invention.

[0062] In summary, conventional lenses have a problem of too short depth of field when used at short working object distances, which may result in reduced operating accuracy. Furthermore, existing extended depth of field lenses do not inherently have the ability to extend the depth of field for the same color of light. Therefore, the present invention further provides a multifocal lens that has the ability to extend the depth of field for the same color of light (see Figure 1 and Figure 2 ), the mold for manufacturing the multifocal lens (refer to Figure 3 ) and an optical machine using the multifocal lens (refer to Figures 6A to 8 In the present invention, when operating with light sources of different colors, the depth of field of the multi-focal lens can be further extended.

[0063] Although the present invention has been disclosed through the foregoing examples, they are not intended to limit the present invention. Any person skilled in the art of the present invention may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined by the appended claims.

Claims

1. An optomechanical structure, comprising: a light source for projecting light toward the work surface to generate reflected light; A multifocal lens, comprising: a first curved surface having a first focal length and comprising a plurality of first curved surface rings; and A second curved surface has a second focal length and includes a plurality of second curved surface rings, wherein: The first curved surface and the second curved surface are alternately arranged on the incident surface in the radial direction of the lens; and a light sensor configured to receive the reflected light through the multifocal lens, wherein the light source and the light sensor are arranged along a first direction, The light source is configured to emit a first color light and a second color light different from the first color light, and the operable depth of field of the multifocal lens is expanded by changing the wavelength of the light source to change the first focal length and first depth of field of the first curved surface and the second focal length and second depth of field of the second curved surface relative to the multifocal lens. The multifocal lens is partially cut in a direction toward the light source, so that the number of the first curved surface rings and the second curved surface rings in the direction toward the light source is less than the number of the first curved surface rings and the second curved surface rings in a direction away from the light source.

2. The optomechanical structure according to claim 1, further comprising a light-transmitting member, the light-transmitting member comprising: a first lens structure, disposed above the light source and having a first optical axis; and a second lens structure, the second lens structure being disposed above the light sensor and having a second optical axis, in, The first optical axis is offset from a first centerline of the light source toward the light sensor in the first direction, and the second optical axis is offset from a second centerline of the light sensor toward the light source in the first direction.

3. The optomechanical structure according to claim 2, wherein: The multifocal lens is aligned with the second lens structure, and The multifocal lens and the second lens structure are integrally formed on the light-transmitting element.

4. The optical-mechanical structure according to claim 1 , further comprising a light blocking member, the light blocking member comprising: a first accommodating space, the first accommodating space being used to accommodate the light source; a second accommodating space, the second accommodating space being used to accommodate the light sensor; and A light-blocking wall extends from the light-blocking member and is located between the first accommodating space and the second accommodating space.

5. The optomechanical structure according to claim 1, wherein: The first focus of the first focal length and the second focus of the second focal length are located on the same optical axis of the multifocal lens.

6. The optomechanical structure according to claim 1, wherein: The first depth of field of the first curved surface and the second depth of field of the second curved surface partially overlap in the optical axis direction of the multifocal lens to form an extended depth of field between 2 mm and 10 mm, which is suitable for an optical mouse.

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