JP2998233B2 - Variable focus glasses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to spectacles, and more particularly to variable-focus spectacles used by seniors as reading glasses.

[0002]

2. Description of the Related Art In recent years, various types of reading glasses for the elderly have appeared. One of them is a single focus lens that has been used for the longest time.
FIG. 7A shows a convex lens having a constant curvature on both surfaces as shown in the cross section, and is used only when looking close to the entire field of view as shown by the hatched portion in FIG. 7B. Therefore, the spectacles are usually used only for reading newspapers or the like. At other times, it is necessary to remove the spectacles or use concave lens spectacles for myopia. For this reason, some people always carry two types of glasses, which is complicated.

On the other hand, a multifocal lens as shown in FIG. 8 has appeared, and has become popular as so-called bifocal glasses. As shown in the cross section of FIG. 8A, this lens is obtained by joining one or more types of lenses having different curvatures to an area often used to look close (shaded area in FIG. 8B). Thus, it is possible to alternately look far and near without changing the glasses.

Further, as an improvement, FIG.
(A) and (B) show a progressive multifocal lens in which the curvature of both surfaces changes continuously, as shown in the cross-sectional view and the front view, respectively. This lens has an advantage that it has less discomfort than the multifocal lens of FIG. 8 because the focal length changes continuously from a far point to a near point.

[0005]

When an elderly person drives a car, for example, it is necessary to frequently look at a display panel (near point) such as a speedometer in addition to seeing the outside (distant). However, in the case of the single focus lens shown in FIG. 7, in order to alternately view the distance, it is necessary to wear or remove glasses, or to replace some people with myopia glasses,
It is practically unusable.

Further, in the multifocal lens shown in FIG. 8 and the progressive multifocal lens shown in FIG. 9, it is possible to correspond to the far and near points in a stepwise or continuous manner. Because it is located near the center, when you actually look close, you move not only your eyes but also your face,
It is necessary to position the near lens area between the viewing target and the eyeball. In particular, when looking at the display panel obliquely below, the face must be largely moved in that direction. For this reason, there is a problem that the vehicle must be driven in an extremely dangerous state, especially when driving at high speed or on a congested road.

[0007] Therefore, there is a problem that the above problem must be solved.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide variable-focus spectacles whose focal length can be freely changed in response to a line-of-sight movement in any direction.

[0009]

According to the variable focus spectacles according to the present invention, (i) a variable focus liquid crystal lens which changes a focal length in response to a given control voltage, and (ii) a variable focus liquid crystal lens. A holding eyeglass frame, (iii) a plurality of sensors fixed to the eyeglass frame and detecting a change in skin potential due to movement of the eyeball, and (iv) a movement angle of the line of sight based on the output of these sensors. (V) driving means for driving the varifocal liquid crystal lens based on the output of the calculating means.

[0010]

In the varifocal eyeglasses according to the present invention, the movement angle of the line of sight and the distance to the object to be viewed are obtained from the outputs of a plurality of sensors fixed to the eyeglass frame, and the focal length of the varifocal liquid crystal lens is determined by a control voltage corresponding thereto. , It is possible to quickly respond even if the line of sight alternates between perspectives.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows variable-focus glasses according to an embodiment of the present invention. As shown in this figure, the variable-focus liquid crystal lenses 11 and 12 for the left eye and the right eye are held by an eyeglass frame 13. These lenses are well-known variable focus liquid crystal lenses whose focal lengths continuously change according to the level of the applied control voltage.

Sensors 14 to 19 and 21 for detecting a change in bioelectric potential are fixed to the positions shown in the drawing of the spectacle frame 13, respectively. These sensors detect the potential generated on the skin around the eyeball due to the movement of the eyeball. Among them, the sensors 14 and 15 detect a change in the potential of the right eye in the left-right direction, and the sensors 16 and 17 detect the potential change in the right and left directions. Detects a left-right potential change of the left eye. In addition, the sensors 18, 1
Reference numeral 9 denotes a sensor for detecting a change in potential in the vertical direction, all of which are paired. The sensor 21 is for grounding a portion having a small potential change. All of these sensors come into close contact with the skin when the spectacle frame 13 is worn.

The potential outputs detected by these sensors are connected to a control box 23 via a signal cable 22.

FIG. 2 shows an internal circuit of the control box 23 of FIG. This circuit includes seven input terminals 24-1 to 24-6 and an input terminal 24-7,
They are connected to sensors 14 to 19 and sensor 21, respectively. The input terminals 24-1 and 24-2 are connected to the first difference amplifier 26, and the input terminals 24-3 and 24-4
Are connected to a second difference amplifier 27. Input terminal 2
4-5 and 24-6 are connected to the third difference amplifier 28. The ground terminals of these difference amplifiers are connected to the input terminal 24.
-7.

The outputs of the first to third differential amplifiers 26 to 28 are input to an arithmetic circuit 29, where a predetermined operation is performed. The arithmetic circuit 29 includes a first applied voltage control circuit 32 for controlling a drive voltage applied to the variable focus liquid crystal lens 11 for the right eye and a drive voltage applied to the variable focus liquid crystal lens 12 for the left eye. A second applied voltage control circuit 33 is connected.

The operation of the varifocal spectacles configured as described above will be described. When the eyeglass frame 13 is worn and the line of sight is moved in a predetermined direction, a potential corresponding to the movement amount and the movement direction is generated on the skin around both eyes. These potentials are detected by sensors 14 to 19 and input to input terminals 24-1 to 24-6 of control box 23. Further, the potential detected by the sensor 21 is input to the input terminal 24-7.

The two potentials input from the input terminals 24-1 and 24-2 are input to a first difference amplifier 26, and the difference between these potentials is amplified and input to the arithmetic circuit 29 as a first output voltage. . This potential difference corresponds to the horizontal movement angle of the line of sight of the right eye. Input terminals 24-3, 2
2-4 are supplied to the second differential amplifier 2
7, and these potential differences are amplified and input to the arithmetic circuit 29 as a second output voltage. This potential difference corresponds to the horizontal movement angle of the line of sight of the left eye. Similarly, the two potentials input from the input terminals 24-5 and 24-6 are input to a third difference amplifier 28, and the potential difference between them is amplified and input to the arithmetic circuit 29 as a third output voltage. . This output voltage corresponds to the vertical movement angle of the line of sight of both eyes.

The arithmetic circuit 29 includes difference amplifiers 26 to 28
A / D (analog / digital) conversion is performed on the output voltage from the camera, and based on the digital data, the horizontal movement angle and the vertical movement angle of the line of sight of the right and left eyes are calculated. This calculation is performed by substituting the potential difference V into a linear equation corresponding to the output voltage and the line-of-sight angle shown in FIG. 3 and the following equation (1).

Θ = aV (1) Here, the coefficient a is a constant determined for each individual by a calibration performed before using the apparatus.

Here, as shown in FIG. 4, it is assumed that, for example, a spectacle wearer fixes his or her line of sight to the gazing point 35. At this time,
From the equation (1), the arithmetic circuit 29 calculates from the equation (1) that θL is the horizontal movement angle of the line of sight of the left eye, θR is the horizontal movement angle of the line of sight of the right eye, and θUD is the vertical movement angle of the line of sight of both eyes.
Is required. The arithmetic circuit 29 calculates the distances DL and DR from the right and left eyes to the gazing point 35 by substituting these angles into the following equations 2 and 3.

[0022]

(Equation 1)

[0023]

(Equation 2)

Here, d indicates the distance between the eyes. Also, θ
L and θR are positive for right and negative for left, and θUD is positive for upward and negative for downward.

Further, the arithmetic circuit 29 calculates the optimum focal length of the varifocal liquid crystal lenses 11 and 13 based on the obtained distance data DL and DR and the degree of myopia or hyperopia of the spectacle wearer, and calculates these as the first and second data respectively. 1, applied to the second applied voltage control circuits 32 and 33. These applied voltage control circuits obtain a lens drive voltage value VD corresponding to a given focal length from a corresponding characteristic graph of the focal length f and the lens drive voltage as shown in FIG. (Digital-to-analog) conversion and supply to variable focus liquid crystal lenses 11 and 12, respectively. As a result, the focal lengths of these variable focus liquid crystal lenses change to optimal values,
Image 5 will be accurately imaged on the wearer's retina.

FIG. 6 shows the correspondence between the eye direction and the eye potential for each point of gaze in FIG. (A) of this figure corresponds to the point of view 41 at infinity in FIG. 4, and the eyeball faces forward. In this case,
Since the horizontal movement angle and the vertical movement angle of the line of sight of the right eye and the left eye are all 0, the distances DR and DL to the gazing point 41 are infinite from equations (2) and (3). Becomes

As shown in FIG. 3B, when the line of sight is moved to the right, θ
R is 40 degrees and θL is 45 degrees. In this case,
From the equations (2) and (3), the distances DR and DL are 52
7, 571 mm.

Similarly, FIGS. 9C and 9D show the states when the line of sight is moved to the left and the line of sight is moved to the upper left.

[0029]

As described above, according to the present invention,
The moving angle of the line of sight and the distance to the object to be viewed are determined from the outputs of the plurality of sensors fixed to the spectacle frame, and the focal length of the varifocal liquid crystal lens is controlled by a control voltage corresponding to the angle. The focus can be quickly adjusted even if the object is alternately moved between them, and the visual target can be clearly confirmed.

Further, when the variable-focus glasses of the present invention are applied to, for example, eyeglasses for the elderly, when driving a car, it is possible to quickly read the instrument and the like of the display panel only by moving the line of sight. As a result, the time during which the user looks away from the front is reduced, and the time required for safety confirmation can be secured, so that the possibility of an accident is reduced.

Further, in the future, it is thought that the work opportunities of the elderly will increase as the aging society progresses, but by applying the variable focus glasses of the present invention, the visual handy under various working environments can be overcome. It is also possible, and its utility value is extremely high.

[Brief description of the drawings]

FIG. 1 is an external view of varifocal spectacles according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal circuit of a control box in FIG.

FIG. 3 is an explanatory diagram showing a correspondence relationship between a change in the potential of the skin around the eyeball and a viewing angle.

FIG. 4 is an explanatory diagram showing a positional relationship between both eyes and a gazing point;

FIG. 5 is an explanatory diagram showing a correspondence relationship between a focal length of the variable focus liquid crystal lens of FIG. 1 and a lens driving voltage.

FIG. 6 is an explanatory diagram showing a specific example of a relationship between an eyeball direction and a skin potential around the eyeball.

FIG. 7 is an explanatory view showing a conventional single focus lens.

FIG. 8 is an explanatory view showing a conventional multifocal lens.

FIG. 9 is an explanatory diagram showing a conventional progressive multifocal lens.

[Explanation of symbols]

 Reference Signs List 11 Variable focus liquid crystal lens (for right eye) 12 Variable focus liquid crystal lens (for left eye) 13 Eyeglass frame 14-21 Sensor 23 Control box 26-28 Difference amplifier 29 Arithmetic circuit 32 Applied voltage control circuit (for right eye) 33 Apply Voltage control circuit (for left eye)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02C 7/06 G02F 1/13 505

Claims (1)

(57) [Claims] 1. A variable focus liquid crystal lens for changing a focal length in response to a given control voltage, a spectacle frame holding the variable focus liquid crystal lens, a skin potential fixed to the spectacle frame and accompanying a movement of an eyeball. A plurality of sensors for detecting a change in the position, a calculating means for calculating the movement angle of the line of sight and the distance to the viewing target based on the outputs of these sensors, and Varifocal spectacles, comprising: driving means for driving.