KR100843453B1 - Optical movement sensing system - Google Patents

Abstract

An optical system for sensing movement is provided to facilitate manufacture by forming only one of refractive surfaces of a wide-angle lens in a curved surface. An optical system for sensing movement includes a wide-angle lens(L) having a first lens element(LE1) and a second lens element(LE2). The first lens element includes an object side surface(1) and an upper surface(2) which are planes. The second lens element includes an object side surface and an upper surface(3). The object side surface of the second lens element is coupled to the upper surface of the first lens element. The upper surface of the second lens element is an upward convex curved surface and an aspheric surface.

Description

Optical Movement Sensing System

1 is a schematic view of a typical optical pointing device.

2 is a schematic diagram of an optical system for motion sensing according to the present invention;

Figure 3 is a schematic diagram for explaining the operation of the optical system for motion sensing according to the present invention.

4 is a reference diagram for explaining the operation of the optical system for motion sensing according to the present invention;

   (a) is a schematic diagram showing the movement of the subject on the screen,

   (b) is a schematic diagram showing the movement of a subject on an image sensor;

5 is a lens configuration of the optical system for motion sensing according to the first embodiment of the present invention.

6 is a graph showing the MTF characteristic of the first embodiment shown in FIG.

7 is a lens configuration of the optical system for motion sensing according to a second embodiment of the present invention.

8 is a graph showing the MTF characteristic of the second embodiment shown in FIG.

Explanation of symbols on the main parts of the drawings

110 ... light source 120 ... subject

130 ... Lens section 140 ... Light sensor

L ... wide-angle lens AS ... aperture aperture

IS ... Top 1, 2, 3, 4 ...

The present invention relates to a motion sensing optical system used in an optical pointing device and the like, and more particularly, to a motion sensing optical system having a wide field of view and capable of miniaturization.

1 is a schematic diagram showing the principle of a general optical pointing device.

As shown in FIG. 1, the optical pointing device is generally made of an LED or the like and condenses the light reflected from the subject 12 by light emitted from the light source 11 and light emitted from the light source 11. The lens unit 13 and an optical sensor 14 such as an image sensor which detects the movement of the subject 12 by sensing the image collected by the lens unit 13.

In the case of a general optical mouse, the subject 12 is formed of a pad corresponding to the ground or the ground. As the user moves the optical mouse, the relative movement of the subject (ground) is detected by the optical sensor 14 and is pointed to ( Position setting) operation is performed.

Recently, there is an attempt to apply such an optical pointing device to a mobile device such as a mobile communication terminal.

As described above, the optical pointing device applied to the mobile communication terminal uses the surface of the finger as a subject, and detects the movement of the finger or the fingerprint through the optical sensor 14 to perform the pointing operation.

However, such a conventional optical pointing device is not able to increase the finger movement in actual use, causing a great inconvenience for users familiar with the general optical mouse.

As described above, in order to apply an optical pointing device to a mobile device such as a mobile communication terminal, the size of the sensing optical system must be small, the peripheral light quantity can be secured, and the wide angle of view to recognize the large movement of the finger is limited. have.

Therefore, there is a need for an optical system for motion sensing that can overcome this limitation.

The present invention is to solve the above problems, and to provide a motion sensing optical system having a wide field of view is possible to secure the resolution and downsized with a small number to be applicable to a mobile device such as a mobile communication terminal. The purpose.

In addition, an object of the present invention is to provide a motion sensing optical system that can ensure a sufficient amount of ambient light, easy to manufacture and assemble, and can be manufactured at low cost.

In order to achieve the above object, the present invention provides a sensing optical system that collects light reflected from a subject to form an image on an optical sensor, comprising: a first lens element having an object side surface and an image side surface in a plane; A wide-angle lens having a second lens element whose surface is coupled to the image side of the first lens element and whose image surface is curved; It provides a motion sensing optical system comprising a.

Preferably, the object-side surface of the first lens element may be formed as an aspheric surface.

Preferably, the wide-angle lens may have a positive refractive power as a whole.

Also preferably, the following Conditional Expression 1 regarding the thickness of the first lens element and the second lens element may be satisfied.

[Condition 1] 1 ≤ D1 / D2 ≤ 5

Where D1: optical axis thickness of the first lens element

        D2: optical axis thickness of the second lens element

Also preferably, the second lens element may be formed by being laminated or bonded to an upper surface of the first lens element.

Preferably, the first lens element and the second lens element may be integrally molded.

Also preferably, the first lens element and the second lens element may have different refractive indices.

On the other hand, it is preferable that an aperture stop is provided on the image side surface of the first lens element to block unnecessary light.

Preferably, the subject may reflect light emitted from the light source unit.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram of the optical system for motion sensing according to the present invention, Figure 3 is a schematic diagram for explaining the operation of the optical system for motion sensing according to the present invention, Figure 4 illustrates the operation of the optical system for motion sensing according to the present invention. For reference, (a) is a schematic diagram showing the movement of the subject on the screen, and (b) is a schematic diagram showing the movement of the subject on the image sensor. 5 is a lens configuration of the optical system for motion sensing according to the first embodiment of the present invention. In the following lens configuration, the thickness, size, and shape of the lens have been somewhat exaggerated for explanation, and in particular, the shape of the spherical or aspherical surface shown in the lens configuration is merely an example and is not limited thereto.

As shown in FIG. 2, the optical pointing device according to the present invention includes a light source unit 110 for irradiating light and a lens unit for collecting light reflected from the subject 120 by light emitted from the light source unit 110. 130 and an optical sensor 140 that detects the image collected by the lens unit 130 and detects the movement of the subject 120.

The light source unit 110 may be formed of a high brightness light emitting diode (LED). However, the light source unit 110 is not limited thereto as long as the reflected light is recognized by the light sensor 140. Similarly, the optical sensor 140 is not particularly limited as long as it can detect the movement of the subject 120.

However, the light source unit 110 is preferably made of an infrared LED, so that the light from the outside of the optical system and the light emitted from the light source unit 110 reflected from the subject 120 may be formed, in this case, the light sensor 140. Is preferably a sensor sensitive to infrared rays.

In addition, the subject 120 may be formed of a pad corresponding to the ground or the ground, such as a general optical mouse. In this case, the subject 120 may be configured to directly detect a relative movement of the subject 120 by directly moving a pointing device equipped with an optical system. Can be. However, since the optical system for motion sensing according to the present invention is particularly small, it can be applied to a mobile device such as a mobile communication terminal. In this case, the surface of the finger may correspond to the subject 120. That is, the pointing device may be configured to detect a movement of a finger surface corresponding to the subject 120 and perform a pointing (direction) operation while the pointing device is fixed. In particular, as described below, the optical system for motion sensing according to the present invention has a high resolution, and may be configured to detect a movement of a finger surface (fingerprint) to perform a function similar to that of an optical mouse.

The operation of the optical system for motion sensing according to the present invention will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, the position of the image passing through the lens unit 130 and formed on the optical sensor 140 such as an image sensor varies according to the positions P1, P2, and P3 of the subject 120. That is, when the subject is at the center position P1, the position of the image becomes the center portion of the optical sensor 140, and as the subject moves away from the center position, the image position moves to the periphery of the optical sensor 140.

For example, when the subject moves from the upper right side to the lower left side of the screen in FIG. 4 (a), the position of the image formed by the optical sensor is moved in response to the movement of the subject as shown in FIG. 4 (b). By detecting the movement of the various pointing operations can be performed.

On the other hand, the lens unit 130 needs to have a wide angle of view so as to detect the movement of the subject occurring in a short distance, and the size of the motion sensing optical system provided therein needs to be small enough to reduce the size of the pointing device. .

That is, in order to be applied to a mobile device such as a portable mobile communication terminal, the lens unit 130 needs to have a wide field of view and a short focal length.

To this end, as shown in FIG. 5, the lens unit 130 includes a first lens element LE1 having an object-side surface 1 and an image-side surface 2 as a plane, and an object-side surface 2 as described above. It is preferred to include a wide-angle lens L having a second lens element LE3 which is coupled to the image side 2 of the first lens element LE1 and whose image side 3 is curved. The lens unit 130 preferably satisfies Conditional Expression 1 described below, but the present invention is not limited thereto.

In particular, since the object-side surface 1 of the wide-angle lens (L) is made of a flat surface, the present invention has an advantage that the angle of view can be increased because it is efficient for bending the light beam.

In addition, the image side surface 3 of the second lens element LE2 is preferably formed as an aspherical surface in order to secure the image forming power to the stockpile and to secure the resolution enough to identify the movement of the subject.

The wide-angle lens L including the first lens element LE1 and the second lens element LE2 is formed to have a positive refractive power as a whole to shorten the overall length of the optical system and simultaneously provide light such as an image sensor. The size of the sensor can be reduced.

In addition, the second lens element LE2 may be formed by being laminated or bonded to the upper surface 2 of the first lens element LE1 in order to facilitate manufacturing. For example, the second lens element LE2 may be laminated on the image surface 2 of the first lens element LE1 having a planar surface on both sides in a replica manner to facilitate mass production, but the wide-angle lens L ) Is not limited to lenses produced by this method. As such, when the first lens element LE1 and the second lens element LE2 are separately formed, the first lens element LE1 and the second lens element LE2 are formed of materials having different refractive indices, thereby increasing the refractive surface. The effect of can be obtained.

Unlike the above, the first lens element LE1 and the second lens element LE2 may be integrally molded. That is, the wide-angle lens L may be formed such that the object side surface 1 is made flat and the image side surface 3 is made curved.

On the other hand, in order to reduce the installation space of the aperture diaphragm AS to reduce the size of the optical system and improve the assemblability, it is preferable that the aperture diaphragm AS is provided on the upper surface 2 of the first lens element LE1. Do. The aperture stop AS may be installed by a known method such as coating a light blocking material on the upper surface 2 of the first lens element LE1. However, the position of the aperture stop AS according to the present invention is not limited to the example shown in FIG. 5 or the like, and may be provided at the front end of the wide-angle lens L. FIG.

In addition, the wide-angle lens L according to the present invention has the advantage that the object-side surface 1 of the first lens element LE1 is formed in a plane, so that manufacturing is easy. In particular, since one surface of the wide-angle lens (L) is flat, there is an advantage that the dicing is advantageous when manufacturing the wide-angle lens (L) by a replica process. That is, since only one surface 3 is formed as a curved surface, there is an advantage that the manufacturing is extremely easy.

In addition, there is an advantage that the image side surface 3 of the second lens element LE2 is formed in a curved surface to maximize the resolution.

In addition, since the optical system for motion sensing according to the present invention uses only one wide-angle lens L, the size of the optical system can be minimized.

Under this overall configuration, the effect of the following Conditional Expression 1 will be described.

[Condition 1] 1 ≤ D1 Of D2  ≤ 5

Here, D1 is an optical axis thickness of the first lens element LE1, and D2 is an optical axis thickness of the second lens element LE2.

Conditional Expression 1 is a condition regarding the ratio of the thicknesses of the first lens element LE1 and the second lens element LE2 constituting the wide-angle lens L. FIG.

If the outside of the lower limit of Conditional Expression 1 is reduced, the lens diameter becomes smaller, which makes it difficult to form the lens and lowers the resolution. On the contrary, the thickness of the optical system increases when it is out of the upper limit of Conditional Expression 1.

Hereinafter, the optical system for motion sensing including the wide-angle lens L will be described through specific numerical examples.

As described above, the wide-angle lenses L of Embodiments 1 and 2 condense the light reflected from the subject 120 by the light emitted from the light source unit 110 to form an image on the optical sensor 140. It is used in the optical system for motion sensing.

In this case, the wide-angle lens L has a first lens element LE1 having an object side surface 1 and an image side surface 2 in a plane, and an object side surface 2 of the first lens element LE1. It has a second lens element LE3 which is coupled to the image side 2 and whose image side 3 is curved. In addition, the image side surface 3 of the wide-angle lens L is composed of an aspherical surface.

An aperture diaphragm AS is provided inside the wide-angle lens L to block unnecessary light, and an image plane IS is disposed at the rear end of the image-side surface 3. The upper surface IS is reflected from the subject 120 in response to the optical sensor 140 of FIG. 2 to sense the light collected by the lens unit 130.

The aspherical surface used in each of the following examples is obtained from known equation (1).

Where Z is the distance from the apex of the lens to the optical axis direction

        Y: distance in the direction perpendicular to the optical axis

        c: inverse of the radius of curvature r at the vertex of the lens

        K: Conic constant

        A, B, C, D, E, F: Aspheric coefficient

[First Example ]

Table 1 below shows numerical examples according to the first embodiment of the present invention.

5 is a lens configuration diagram showing the lens arrangement of the optical system for motion sensing according to the first embodiment of the present invention, and FIG. 6 is a graph showing the MTF characteristics of the first embodiment shown in FIG.

In the first embodiment, the total focal length f of the optical system is 0.344 mm, the angle of view 2ω is 120 °, and the F number is 3.0.

In Table 1, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B) according to Equation 1 are shown in Table 2 below.

[Second Example ]

Table 3 below shows a numerical example according to the second embodiment of the present invention.

7 is a lens configuration diagram showing the lens arrangement of the optical system for motion sensing according to the second embodiment of the present invention, and FIG. 8 is a graph showing the MTF characteristics of the second embodiment shown in FIG.

In the second embodiment, the total focal length f of the optical system is 0.278 mm, the angle of view 2ω is 150 °, and the F number is 3.0.

In Table 3, * represents an aspherical surface, and the values of the koenic constant (K) and the aspherical coefficients (A, B) according to Equation 1 are shown in Table 4 below.

On the other hand, as shown in the MTF graph of Figures 6 and 8, based on 0.3 (30%) it is possible to ensure a resolution of 50 cycle / mm or more, it is possible to sufficiently detect the movement of the subject.

For example, as shown in FIG. 4, when the screen is divided into nine regions, in order to detect each region separately from other regions, there are some differences depending on the size of the image sensor (light sensor) or the number of pixels. However, resolution of about 5 cycles / mm is required. In view of this, it can be seen that the embodiment of the present invention sufficiently secures the resolution capable of identifying the movement of the subject.

In particular, since resolution of 50 cycles / mm or more can be realized, motion sensing using a finger surface (fingerprint) can be performed, and thus an advantage similar to that of an optical mouse can be performed.

As described above, according to the present invention, since only one wide-angle lens can detect the movement of the subject, the optical system can be miniaturized and thinned, which can be applied to a mobile device such as a mobile communication terminal.

In particular, it has a wide angle of view of more than 120 ° and can secure a sufficient amount of peripheral light, there is an effect that it is possible to sufficiently detect the movement of the subject in the peripheral portion of the optical sensor.

In addition, according to the present invention, since the aperture stop is located inside the wide-angle lens, a separate space for installing the aperture stop is not required and the installation work of the aperture stop is not required, thereby achieving an effect of improving assembly.

In addition, since the object-side surface of the wide-angle lens is formed in a plane and efficient in bending the light beam, the angle of view can be increased, and the image-side surface is formed in a curved surface, thereby sufficiently securing the resolution capable of detecting the movement of the subject. It is effective. In particular, since only one surface of the refractive surface of the wide-angle lens is formed as a curved surface, there is an advantage that it is extremely easy to manufacture, and since only one wide-angle lens is used, the size of the optical system can be minimized.

While the invention has been shown and described with respect to particular embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I want to make it clear.

Claims (9)

In the optical system for motion sensing for condensing the light reflected from the subject from the light source to form an image on the light sensor, A wide-angle lens having a first lens element having an object side surface and an image side plane and a second lens element having an object side surface coupled to an image side surface of the first lens element and having an image side surface convex toward the image side and having an aspherical surface. ; Optical system for motion sensing comprising a. delete The method of claim 1, The optical lens for a motion sensing, characterized in that the wide-angle lens as a whole has a positive refractive power. The method of claim 1, And the following Conditional Expression 1 is satisfied with respect to the thickness of the first lens element and the second lens element. [Condition 1] 1 ≤ D1 / D2 ≤ 5 Where D1: optical axis thickness of the first lens element         D2: optical axis thickness of the second lens element The method according to any one of claims 1, 3 and 4, And the second lens element is formed by being laminated or bonded to an image surface of the first lens element. The method according to any one of claims 1, 3 and 4, And the first lens element and the second lens element are integrally molded. The method according to any one of claims 1, 3 and 4, And the first lens element and the second lens element have different refractive indices. The method according to any one of claims 1, 3 and 4, An optical aperture for motion sensing, characterized in that an aperture diaphragm for blocking unnecessary light is provided on an image side surface of the first lens element. The method according to any one of claims 1, 3 and 4, And the subject reflects light emitted from the light source unit.

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