CN109240022B

CN109240022B - Zoom lens

Info

Publication number: CN109240022B
Application number: CN201710560639.9A
Authority: CN
Inventors: 洪伟智; 林信忠; 王欣仁
Original assignee: Rays Optics Inc
Current assignee: Young Optics Inc
Priority date: 2017-07-11
Filing date: 2017-07-11
Publication date: 2021-09-28
Anticipated expiration: 2037-07-11
Also published as: CN109240022A

Abstract

The invention discloses a zoom lens, which comprises a zoom lens group, a focusing lens group and a photo interrupter. The optical interrupter is used for detecting the position of the zoom lens group or the focusing lens group, the optical interrupter comprises a light emitting element and a light receiving element which can form an optical path, and the peak wavelength of a light beam emitted by the light emitting element is larger than 860 nm.

Description

Zoom lens

Technical Field

The present invention relates to a zoom lens.

Background

The use of a camera with a zoom lens to enable a user to adjust the focal length according to his/her own needs is now quite popular. The zoom lens may be provided with a photo interrupter for detecting the change of the light shielding state and the non-light shielding state to confirm the position of the movable lens group in the zoom lens. However, the infrared ray emitted from the photo interrupter during the activation will form an image on the image sensor to form a noise image called ghost, which affects the picture quality. One conventional approach is to place a photo-interrupter at the end point and use mechanical components to block infrared rays to reduce ghosting, but this approach cannot greatly reduce or completely avoid ghosting.

Disclosure of Invention

Other objects and advantages of the present invention will be further understood from the technical features disclosed in the embodiments of the present invention.

An embodiment of the present invention provides a zoom lens, including a zoom lens set, a focusing lens set and a photo interrupter. The optical interrupter is used for detecting the position of the zoom lens group or the focusing lens group, the optical interrupter comprises a light emitting element and a light receiving element which can form an optical path, and the peak wavelength of a light beam emitted by the light emitting element is larger than 860 nm. In a preferred range, the peak wavelength of the light beam emitted by the light emitting element can be greater than 890 nm. In a more preferred range, the peak wavelength of the light beam emitted by the light emitting device can be greater than 950 nm.

An embodiment of the present invention provides a zoom lens, which is used for an image capturing device with an image sensor and includes a zoom lens group, a focusing lens group and a photo interrupter. The photo interrupter is used for detecting the position of the zoom lens group or the focusing lens group, and the peak wavelength of the light beam emitted by the photo interrupter is positioned outside a sensing wavelength range of the image sensor. If the quantum efficiency of the image sensor at the peak of the optical response of the light beam is defined as 100%, the sensing wavelength range corresponds to a wavelength range of more than 15% of the quantum efficiency.

In another embodiment of the present invention, a zoom lens includes a zoom lens set, a focusing lens set, a first photo interrupter and a second photo interrupter. The first photo interrupter is used for detecting the position of the zoom lens set and is provided with a first circuit, the second photo interrupter is used for detecting the position of the focusing lens set and is provided with a second circuit, and the first circuit and the second circuit can respectively and independently operate.

In another embodiment of the present invention, a zoom lens includes a zoom lens set, a focusing lens set, a first photo interrupter and a second photo interrupter. The zoom lens group and the focusing lens group can move on an optical axis to respectively carry out zooming and focusing operations. The first photo interrupter is used for detecting the position of the zoom lens set, the second photo interrupter is used for detecting the position of the focusing lens set, and the second photo interrupter is closed when the first photo interrupter is actuated.

By means of the design of the embodiments of the present invention, the peak wavelength of the light beam emitted by the photo interrupter is outside a sensing wavelength range of the image sensor, and the image sensor does not image the light emitted by the photo interrupter, thereby avoiding the generation of ghost image. Furthermore, because the first photo interrupter and the second photo interrupter can be operated independently, the first photo interrupter and the second photo interrupter, or the actual focusing mode of the zoom lens can be operated alternatively to determine the opening and closing timing of the first photo interrupter and the second photo interrupter, so as to effectively reduce or completely avoid the generation of ghost image.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following preferred embodiments are described in detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic view of a zoom lens according to an embodiment of the present invention.

Fig. 2 shows spectral distribution curves of the light emitting device and the light receiving device of a photo interrupter.

FIG. 3 shows an optical response diagram of an image sensor.

FIG. 4 shows a schematic block diagram of a zoom lens according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view of the zoom lens of FIG. 4.

Detailed Description

The foregoing and other technical and scientific aspects, features and advantages of the present invention will be apparent from the following detailed description of various embodiments, which is to be read in connection with the accompanying drawings. Directional phrases used in the following embodiments, such as, for example, upper, lower, front, rear, left, right, etc., refer only to the directions of the appended drawings. Accordingly, the directional terminology is used for purposes of illustration and is in no way limiting.

FIG. 1 is a schematic view of a zoom lens according to an embodiment of the present invention. As shown in fig. 1, the zoom lens 10 has a zoom lens group (focusing lens group)12, a focusing lens group (focusing lens group)14, a first photo interrupter 16, and a second photo interrupter 18. In a typical photo interrupter, there are a light emitting device and a light receiving device forming a light path, and there is an air gap between the light emitting device and the light receiving device, if there is no object in the gap to block, the light emitted from the light emitting device will directly irradiate the light receiving device; on the other hand, if there is an object in the gap to block the light, the light receiving element will not irradiate the light and change the output state. Therefore, the first photo interrupter 16 can confirm the position of the zoom lens assembly 12 by detecting the change of the light shielding state and the non-light shielding state, and the second photo interrupter 18 can confirm the position of the focusing lens assembly 14 by detecting the change of the light shielding state and the non-light shielding state. In the present embodiment, the peak wavelengths of the light beams emitted from the light emitting elements (not shown) of the first photo interrupter 16 and the second photo interrupter 18 are both greater than 860nm, a preferred range is that the peak wavelength is greater than 890nm, and a more preferred range is that the peak wavelength is greater than 950 nm. Fig. 2 shows spectral distribution curves of the light emitting element and the light receiving element of the photo interrupter. As shown in fig. 2, the light emitting element may be an infrared-emitting diode (IR LED) using gallium arsenide (GaAs) material, and the light emitting peak wavelength is about 950 nm. Furthermore, fig. 3 shows an optical response diagram of the image sensor, as shown in fig. 3, when the wavelength of the incident light of the red light incident on the image sensor is larger than 860nm, the quantum efficiency has been reduced to below 16%, and when the wavelength of the incident light of the red light is larger than 950nm, the quantum efficiency can be further reduced to below 6%, i.e. the image sensor is hardly sensitive to the incident light of the red wavelength. Similarly, when the quantum efficiency of the image sensor at the time when the optical response of the image sensor to Infrared (IR) is at the peak is defined as 100%, the quantum efficiency of the Infrared (IR) having a higher wavelength incident on the image sensor is reduced to, for example, 15%, 10%, or 5% or less with respect to the peak, and thus ghost is less likely to occur. Therefore, in an embodiment of the present invention, the peak wavelength of the light beams emitted by the first photo interrupter 16 and the second photo interrupter 18 is outside a sensing wavelength range of the image sensor for sensing Infrared (IR), if the quantum efficiency of the image sensor at the peak of the optical response of the image sensor to the Infrared (IR) is 100%, the sensing wavelength range of the image sensor in this embodiment may be a wavelength range corresponding to a quantum efficiency greater than 15%, the sensing wavelength range in another embodiment may be a wavelength range corresponding to a quantum efficiency greater than 10%, and the sensing wavelength range in yet another embodiment may be a wavelength range corresponding to a quantum efficiency greater than 5%. When the peak wavelength of the light beam emitted from the photo interrupter is outside a sensing wavelength range of the image sensor sensing Infrared (IR), the image sensor can hardly image the light emitted from the first photo interrupter 16 and the second photo interrupter 18, and thus the generation of ghost can be greatly reduced or avoided.

The zoom lens system according to the embodiment of the present invention is not limited in its components, and the movable lens group (e.g. zoom lens group or focusing lens group) shown in fig. 1 may be combined with other fixed lens groups in an unlimited number. As shown in FIG. 4, an image capturing device 1 comprises a zoom lens 20, a light filter 3 disposed on an image side of the zoom lens 20, and an image sensor 4 for generating an image, wherein the zoom lens 20 comprises a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4 and a fifth lens group G5, the second lens group G2 and the fourth lens group G4 are movable lens groups, and the remaining lens groups are fixed lens groups. The second lens group G2 can be a zoom lens group, and the fourth lens group G4 can be a focusing lens group. The image sensor 4 may be, for example, a photo-coupled device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS). FIG. 5 is a schematic cross-sectional view of the zoom lens embodiment of FIG. 4. As shown in fig. 5, the second lens group G2 (zoom lens group) of the zoom lens 20 moves in the optical axis 2 direction for zooming operation, and the fourth lens group G4 (focusing lens group) moves in the optical axis 2 direction for focusing operation, the direction of arrow X is the direction in which the zoom lens group G2 moves from the wide-angle end to the telephoto end, and the direction of arrow-X is the direction in which the zoom lens group G2 moves from the telephoto end to the wide-angle end. The driving mechanism 22 drives the zoom lens group G2 along the direction of the optical axis 2, and the driving mechanism 24 drives the focusing lens group G4 along the direction of the optical axis 2. The driving mechanism 22 and the driving mechanism 24 can be, for example, a stepping motor, a voice coil motor, a piezoelectric element, and the like without limitation. The photo interrupter 16 can confirm the position of the zoom lens assembly G2 by detecting the light shielding state and the non-light shielding state of the light shielding portion 222 disposed on the zoom lens assembly G2, and the photo interrupter 18 can confirm the position of the focusing lens assembly G4 by detecting the light shielding state and the non-light shielding state of the light shielding portion 242 disposed on the focusing lens assembly G4.

Furthermore, according to an embodiment of the present invention, the first photo interrupter 16 and the second photo interrupter 18 may have circuits that operate independently of each other, for example, the first photo interrupter 16 and the second photo interrupter 18 may have separate anode/cathode structures, so that the first photo interrupter 16 and the second photo interrupter 18 can be turned off or on independently. With this design, the first photo interrupter 16 and the second photo interrupter 18 can be controlled independently to avoid ghost image, for example, when the zoom lens assembly 12 performs zooming (zoom), the first photo interrupter 16 can be activated to confirm the position of the zoom lens assembly 12, and the second photo interrupter 18 can be turned off; on the other hand, when the focusing lens group 14 performs focusing operation (focusing), the second photo-interrupter 18 can be activated to confirm the position of the focusing lens group 14, and the first photo-interrupter 16 can be turned off. The generation of ghost image can be effectively reduced or avoided by the alternating action of the first photo-interrupter 16 and the second photo-interrupter 18. With the design of the above embodiment, since the first photo interrupter 16 and the second photo interrupter 18 can be independently operated, the first photo interrupter 16 and the second photo interrupter 18 can be alternatively operated, or the actual focusing manner of the zoom lens can be used to determine the opening/closing timing of the first photo interrupter 16 and the second photo interrupter 18, so as to effectively reduce or completely avoid the occurrence of ghost image.

Although the present invention has been described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, not all objects, advantages, or features disclosed herein are to be achieved in any one embodiment or claim of the present invention. In addition, the abstract and the title are provided to assist the patent document searching and are not intended to limit the claims of the present invention.

Claims

1. A zoom lens, comprising:

a zoom lens group and a focusing lens group;

a first photo interrupter for detecting a position of the zoom lens assembly;

a first circuit for turning on or off the first photo interrupter;

a second photo interrupter for detecting the position of the focusing lens set; and

a second circuit for turning on or off the second photo interrupter, wherein the first circuit and the second circuit are used for independent operation, and the zoom lens satisfies one of the following conditions: (1) the first photo interrupter and the second photo interrupter can be alternately operated, and (2) the opening and closing timing of the first photo interrupter and the second photo interrupter can be determined according to the actual focusing mode of the zoom lens.

2. The zoom lens according to claim 1, wherein a peak wavelength of a light beam emitted from the first photo interrupter is greater than 860 nm.

3. The zoom lens of claim 2, wherein the peak wavelength of the light beam is greater than 890 nm.

4. The zoom lens of claim 3, wherein a peak wavelength of the light beam is greater than 950 nm.

5. The zoom lens of claim 1, wherein the peak wavelength of the light beam emitted by the first photo interrupter is outside a sensing wavelength range of an image sensor, wherein the quantum efficiency of the optical response of the image sensor to the light beam at the peak is 100%, and the sensing wavelength range corresponds to a wavelength range of greater than 15% of the quantum efficiency.

6. A zoom lens, comprising:

the zoom lens group and the focusing lens group are used for moving on an optical axis to respectively carry out zooming and focusing operations;

a first photo interrupter for detecting a position of the zoom lens assembly; and

a second photo interrupter for detecting the position of the focusing lens set, wherein the second photo interrupter is turned off when the first photo interrupter is activated.

7. The zoom lens according to claim 6, wherein a peak wavelength of the light beam emitted from the first photo interrupter is greater than 860 nm.

8. The zoom lens of claim 6, wherein the peak wavelength of the light beam emitted by the first photo interrupter is outside a sensing wavelength range of an image sensor, wherein the quantum efficiency of the optical response of the image sensor to the light beam at the peak is 100%, and the sensing wavelength range corresponds to a wavelength range of greater than 15% of the quantum efficiency.

9. The zoom lens of claim 7, wherein the peak wavelength of the light beam is greater than 890 nm.

10. The zoom lens of claim 9, wherein a peak wavelength of the light beam is greater than 950 nm.

11. The zoom lens according to any one of claims 1 to 10, further comprising at least one fixed lens group.

12. The zoom lens system as claimed in any one of claims 1 to 10, wherein each of the zoom lens group and the focusing lens group has a light shielding portion, and each of the photo interrupters detects a light shielding state and a non-light shielding state generated by the light shielding portion to determine the positions of the zoom lens group and the focusing lens group.