RU2260203C2 - Optical system of optical mouse - Google Patents

Abstract

FIELD: computer manipulators.

SUBSTANCE: mutual position in light guide of input lens surface, mirror and output surfaces, and also light guide and objective-lent, is made such, that angle between lighting beams and subject surface is not less than 20°, and also input lens surface is made such, that lighting beam inside light guides is made dissipating, providing close to parallel output lighting beam with high density of light energy.

EFFECT: higher efficiency.

2 cl, 1 tbl, 3 dwg

Description

The present invention relates to computer vision technology and can be used in contact scanning image converters, in particular in an optical mouse to control the cursor on a computer display screen, in a portable text reader, etc.

Known optical systems of an optical mouse described in US patents: No. 6433780, NKI 345/166 "Seeing mouse for computer systems" and No. 4751505, NKI 340/710 "Optical mouse".

These patents describe optical systems of an optical mouse comprising a lens for transmitting an image of a subject surface to the plane of photodetectors and a light guide directing light from the illuminator to the subject surface.

Closest to the claimed invention is US patent No. 6433780 B1 of the company "Agilent Technologies", which describes an optical system containing a lens of an optical channel for transmitting an image of the working part of the subject surface to the plane of the photodetectors, and a light guide directing light from a illuminator optically coupled to the input lens the surface of the light guide to the subject surface.

However, the known devices have disadvantages: the illumination of the subject surface is heterogeneous and insufficiently concentrated on its working part. Due to excessively wide illumination, the efficiency of the optical system is insufficient for a number of applications, in particular for high-speed and autonomous powered mice.

The technical result of the present invention is to significantly increase the illumination on the working part of the subject surface and reduce the heterogeneity of its lighting.

This result is achieved due to the fact that in a known device containing a lens of an optical channel for transmitting an image of a working part of a subject surface onto an image plane and a light guide having an input lens surface, an output lens surface and at least one mirror surface directing light from the illuminator optically coupled to the input lens surface of the light guide onto the subject surface, it is proposed:

- the relative position in the optical fiber of the input lens surface, the mirror and output surfaces, as well as the optical fiber and the objective lens, so that the angle between the illuminating rays and the subject surface is at least 20 ° (for the prototype this angle is less than 20 °);

- make the input lens surface such that the beam of illuminator rays inside the light guide is convergent, and the output lens surface of the light guide is scattering, providing an output beam of light rays with a high light energy density that is close to parallel;

- perform the output lens surface astigmatic, to obtain a round illuminated spot on the subject surface.

An increase in the illumination of the working surface is achieved due to the concentration of the illuminator beams due to the redistribution of the optical power between the input and output lens surfaces of the light guide, and due to a change in the angle of incidence of the illuminator beams, due to the corresponding relative position of the input lens surface, the mirror and output surfaces, and the light guide and lenses. With a more vertical incidence of rays, the input lens surface concentrates the rays of the illuminator on a small area, which is 5-10 times smaller than the area illuminated by oblique incidence of rays in known devices. Improving the uniformity of illumination of the working part of the subject surface is achieved due to the parallelism of the rays in the light beam emerging from the light guide to the subject surface. The parallelism of the rays is provided by the negative optical power of the output surface. The maximum increase in illumination due to the concentration of rays is achieved if the illuminated spot is round, for this the output lens surface of the light guide is made astigmatic, providing a decrease in the size of the spot along the direction of light incidence.

The list of graphic materials illustrating the claimed invention.

- Figure 1 shows an example implementation of the design of the proposed optical system.

- Figure 2 illustrates the weak dependence of the uneven illumination of the working part of the subject surface in the optical system shown in figure 1, on the variation of its location relative to the illuminator and the subject surface (displacement of the illuminator: 1 - along the optical axis, 2 - perpendicular to the optical axis vertically, 3 - perpendicular to the optical axis horizontally, 4 - the displacement of the optical system relative to the subject surface, 5 - rotation of the axis of the illuminator relative to the optical axis of the input lens surface of the light guide horizontally ntal plane, 6 - rotation of the illuminator axis relative to the optical axis of the input lens surface of the light guide in a vertical plane).

The optical system comprises a lens 1 of an optical channel for transmitting an image of a portion of a subject surface 2 onto an image plane 3 and a light guide 4 having an input lens surface 5, an output lens surface 6 and a mirror surface 7 directing and concentrating light from the illuminator 8 on the working part 9 of the subject surface 2 The parameters of the optical surfaces of the design of the optical system shown in figure 1, determined using the Zemax program, are presented in table 1.

The proposed optical system operates as follows. The light from the emitter 8 is converted by the input lens surface 5 of the dielectric light guide 4 into a converging beam. This light, due to the effect of total internal reflection on the mirror dielectric surface 7 of the light guide, changes the propagation direction and falls on the concave surface 6 at an angle of 45 ° to the horizontal. The optical surface 6 converts the converging beam into a parallel one. Thus, the optical surfaces 5 and 6 can reduce the diameter of the beam and double the density of light energy in it. The surface 6 is rotated so that the central beam forms an angle of 10 ° with the normal to the surface. Due to the refraction effect, the rays emerging from the surface 6 change their direction in a direction more vertical with respect to surface 2. The angle of incidence of the rays to the horizontal increases to 51 °. These rays illuminate the working part of the subject surface with great intensity and good uniformity. The size of the light spot and the distribution of illumination in it weakly depend, as it follows from Fig. 2, on deviations of the alignment dimensions that determine the location of the illuminator 8, the light guide 4 and the subject surface 2. The image of the illuminated working part 9 of the subject surface 2 is transmitted by the lens 1 to the image plane where photodetectors are located.

The advantage of the proposed design is that it provides a significant reduction in the size of the illuminated area of the subject surface 2 and good uniformity of lighting, resistant to deviations from the nominal values of its structural elements.

Table 1 1. The distance between the lighting LED and the input surface of the light guide. 0.3 mm 2. The input optical surface 5 (r is the coordinate perpendicular to the optical axis, z is the coordinate along the optical axis in the direction of light propagation).

3. The refractive index of the material of the optical system 1,58 4. The length of the optical path inside the light guide 15 mm 5. Output optical surface Spherical concave, radius of curvature 13.5 mm, the surface is rotated around the point of intersection with the central beam by 10 ° clockwise. 6. The distance from the exit point of the Central beam to the subject surface 4,5 mm 7. The distance from the exit point of the Central beam to the optical axis of the lens 3.8 mm 8. The distance from the subject surface to the lower surface of the lens 5.55 mm 9. The lower surface of the objective lens (r is the coordinate perpendicular to the optical axis, z is the coordinate along the optical axis up).

10. The distance from the bottom surface of the lens to the top 2.4 mm 11. The upper surface of the lens Spherical with a radius of curvature of 3.4 mm. 12. The distance from the upper lens to the surface of the photodetectors. 5.55 mm

Claims (2)

1. The optical system of an optical mouse, comprising a lens of an optical channel for transmitting an image of a working part of a subject surface onto an image plane and a light guide having an input lens surface, an output lens surface and at least one mirror surface directing light from a illuminator optically coupled to the input lens surface optical fiber, on the subject surface, characterized in that the relative position in the optical fiber of the input lens surface, mirror and output surface it, as well as the light guide and lenses, are designed so that the illuminating rays fall on the object surface at an angle from 20 to 90 ° to this surface, the input lens surface providing a converging beam of light directed to the mirror surface, and the output lens surface of the light guide is made scattering and changing a converging beam directed at it by a mirror surface into a close parallel beam. 2. The optical system of the optical mouse according to claim 1, characterized in that the output lens surface of the light guide is made astigmatic, providing a round illuminated spot on the subject surface.

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