Method and apparatus for lens auto-focusing in camera module test

Abstract

A lens auto-focusing method in camera module testing includes the following steps: providing testing equipment including a range finder, a signal processor and a driving member; providing an imaged object (20); providing an camera module including a lens module (10) and an image sensor, the view angle and the biggest value of the modulation transfer function of the lens module are both certain values, the image (30) of the imaged object is formed in the image sensor; the imaged object and the image formed thereby in the other side of the lens module are fixed; the imaged object and the image formed in the other side of the lens module are fixed; inputting an image distance tested by the range finder into the signal processor, the signal processor calculates a displacement for the driving member; the driving member drives the lens module to a focusing point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the lens auto-focusing method in camera module test and the apparatus employing the same can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present digital camera module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

FIG. 1 is an imaging optical path view of a lens module used in an embodiment of the present invention in camera module test; and

FIG. 2 is a graph showing the change in image height with respect to the displacement of the driving member in accordance with the embodiment of the invention.

Claims

1. A method of lens auto-focusing in camera module test includes the following steps: providing testing equipment, wherein the testing equipment includes a range finder, a signal processor and a driving member all connected electrically;providing an imaged object;providing an camera module including a lens and an image sensor, wherein a view angle and the biggest value of modulation transfer function of the lens module are both certain values; an image of the imaged object is formed in the image sensor; the imaged object and the image formed thereby in the other side of the lens module are fixed; andinputting an initial image distance tested by the range finder into the signal processor, wherein the signal processor calculates the initial image height based on the initial image distance, and further calculates a displacement for the driving member, then the signal processor generates a controlling signal and sends the signal to the driving member to control it, the driving member then drives the lens module to a focusing point.

2. The lens auto-focusing method in camera module test as claimed in claim 1, wherein the biggest modulation transfer function value of the lens module is input into the signal processor before testing.

3. The lens auto-focusing method in camera module test as claimed in claim 2, wherein a linear equation of the displacement of the driving member and the changing of the image height is x=n(y−S1), wherein x is the displacement of the driving member, y is the image height when the driving member has moved, S1 is the image height without moving of the driving member, y−S1 is the changing of the image height, n is the linear coefficient.

4. The lens auto-focusing method in camera module test as claimed in claim 3, wherein the linear coefficient n is equal to the ratio of the image distance to the image height, that is, n is equal to the tangent of a given angle related to the view angle of the lens module.

5. The lens auto-focusing method in camera module test as claimed in claim 1, wherein the driving member is a driving motor or a solenoid valve.

6. The lens auto-focusing method in camera module test as claimed in claim 1, wherein the displacement of the driving member is equal to the displacement of the lens module during the test.

7. The lens auto-focusing method in camera module test as claimed in claim 1, wherein the signal processor is electrically connected with the range finder and the driving member.

8. An apparatus for lens auto-focusing in camera module test, wherein the camera module including a lens module, a view angle and the biggest value of the modulation transfer function of the lens module are certain values, an imaged object and an image formed thereby in the other side of the lens module are fixed, the testing equipment comprising: a range finder for measuring an image distance;a signal processor calculating the displacement of the lens module based on an initial image distance tested by the range finder and a linear equation of the changing of the image height and the displacement of the lens module; anda driving member for driving the lens module to move, and the range finder, the signal processor and the driving member are connected electrically.

9. The testing equipment as claimed in claim 8, wherein the linear equation of the displacement of the driving member and the changing of the image height is x=n(y−S1), wherein x is displacement of the driving member, y is the image height when the driving member has moved, S1 is the image height without moving of the driving member, y−S1 is the changing of the image height, n is a linear coefficient.

10. The testing equipment as claimed in claim 9, wherein linear coefficient n is equal to the ratio of the image distance to the image height, that is, n is equal to the tangent of an given angle related to the view angle of the lens module.

11. The testing equipment as claimed in claim 8, wherein the image height is a certain value when the lens module is in the best position.

12. The testing equipment as claimed in claim 8, wherein driving member is a driving motor or a solenoid.

13. The testing equipment as claimed in claim 8, wherein the displacement of the lens module is equal to the displacement of the driving member during the test.