JP2019144277A - Spectacle lens and manufacturing method therefor - Google Patents

Abstract

To provide a bi-aspheric single focus lens with eccentricity.SOLUTION: Provided is a spectacle lens with a front and back surfaces, the front surface being on the object side and the back surface being on the eye side. A first horizontal cross-section at a first height has a shape of a circular arc A1 centered on a first center C1, and a second horizontal cross-section at a second height has a shape of a circular arc A2 centered on a second center C2, where the first center C1 and the second center C2 are on a same vertical line.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a spectacle lens. More specifically, the present invention relates to a double-sided aspheric single focus lens and a method for manufacturing a double-sided aspheric lens.

  Single focus lenses are widely used to correct refractive errors such as myopia and hyperopia, and are also used as reading glasses.

  In the past and present, the simplest single focus lens comprises a spherical front surface and a spherical or toric back surface. In the next generation, front aspherical single focus lenses were developed. The single-focus lens having the latest structure has an aspherical front surface and an aspherical or atoric rear surface, and a so-called double-sided aspheric single-focus lens is described in Japanese Patent No. 3845251.

  FIG. 1 schematically shows a horizontal sectional view of a conventional double-sided aspherical single focus lens. A thin solid line P1 represents a horizontal sphere in the upper region of the lens. A thick solid line P2 represents a horizontal sphere in the lower region of the lens. A thin arrow line V1 represents a normal vector of the upper region of the lens at a specific position in the lower region of the lens. A thick solid arrow V2 represents a normal vector of the lower region of the lens at a specific position in the lower region of the lens. The specific position of the lower region of the lens corresponds to the passing position of the near line of sight. The passing point depends on the amount of displacement of the line of sight toward the nose due to convergence when the lens wearer is looking at an object at a short distance.

  The thin dashed arrows represent the normal vectors of both the upper and lower regions of the lens at specific positions in the upper region of the lens. The specific position of the upper region of the lens can correspond to the passing position of the distance line of sight. The normal vectors in the upper region of the lens and the lower region of the lens overlap.

  The conventional double-sided aspherical single-focus lens has a characteristic that the normal vector in the upper region of the lens has the same direction as the line of sight, but the normal vector in the lower region of the lens is different from the direction of the line of sight. This is because the center of the far sphere and the center of the near sphere are not at the same position in the vertical direction.

  In other words, the normal vector of the far sphere and the normal vector of the near sphere are in a “twist” positional relationship. The positional relationship of the twist causes an unnecessary prism in the lower region of the lens.

  If a semi-finished lens with an optically finished surface on one side is used to make a double-sided aspherical single focus lens, and processing to obtain the final lens on the other surface is necessary, cancel the unnecessary prism Therefore, it is necessary to be able to use many semi-finished lenses during manufacture. Further, in order to cancel out unnecessary prisms, optical correction of the rear surface is necessary, but a large amount of calculation is required.

  Therefore, in conventional double-sided aspherical single focus lenses, the horizontal section is not axially symmetric (rotationally symmetric) due to torsion, so it is virtually impossible to accept spectacle store order options for decentration. Eccentricity is that the optical center or main reference point of the lens is displaced from the boxing or datum center of the lens aperture of the frame.

  If the eccentricity is possible from the viewpoint of manufacturing, the manufacturing cost can be reduced. Material costs and processing time are reduced by reducing the lens diameter due to eccentricity.

  In order to cancel out unwanted prisms caused by twisting in the lower area of the lens, it is necessary to make many semi-finished lenses with aspheric correction dependent on the prescription for each right eye and left eye. is there.

  Semi-finished lenses are usually symmetrical. A conventional semi-finished lens of a double-sided aspherical single focus lens is bilaterally symmetric, but is not axially symmetric (rotationally symmetric), so the semifinished lens cannot be used eccentrically.

  Lens decentration occurs when the optical center of the lens is not the same as the geometric center of the cut lens of a particular frame. In order to align the optical center and match the frame cutout size, it is necessary to use a larger semi-finished lens. A larger semi-finished lens also means a thicker lens. It is therefore impossible to produce an eccentric lens, ie a lens whose optical center does not coincide with the geometric center of the lens.

Japanese Patent No. 3845251

  In view of the above, an object of the present invention is to provide an eccentric lens. In particular, an object is to provide a decentered double-sided aspheric single focus lens.

  This object is achieved by the subject matter of the independent claims. The dependent claims relate to specific embodiments.

  One aspect relates to a spectacle lens comprising a front surface and a rear surface. The front surface is on the object side, and the rear surface is on the eye side. The first horizontal cross section at the first height represents an arc of a circle having a first center. The second horizontal cross section at the second height represents a circular arc having a second center. The first and second centers are on the same vertical line.

  According to another aspect, the first height corresponds to the upper region of the lens in the upper hemisphere of the lens, and the second height corresponds to the lower region of the lens in the lower hemisphere of the lens.

  According to another aspect, the vertical line is the rotational axis of the rotational symmetry body

  According to another aspect, the vertical cross section includes an aspherical first arc.

  According to another aspect, the first arc of the vertical section corresponds to the lower region of the lens in the lower hemisphere.

  According to another aspect, the spectacle lens includes the front surface and the rear surface, and is aspheric.

  Another aspect relates to a method for manufacturing a spectacle lens according to the above.

It is a figure which shows roughly the horizontal sectional view of the conventional double-sided aspherical single focus lens. It is a figure which shows roughly the horizontal sectional view of the double-sided aspherical single focus lens by one Embodiment of this invention. It is a figure which shows schematically the vertical sectional view of the double-sided aspherical single focus lens by one Embodiment of this invention. It is a flowchart of the manufacturing process of the double-sided aspherical single focus lens by one Embodiment of this invention. FIG. 6 shows a vertical curve along a meridian according to the present invention. It is a figure which shows the comparison of the conventional lens and the lens of this invention in the optical performance confirmation in case the spherical power of prescription is minus. It is a figure which shows the comparison with the conventional lens and the lens of this invention in the optical performance confirmation in case the spherical power of prescription is plus. It is a figure which shows the comparison with the conventional lens and the lens of this invention in the optical performance confirmation in case the spherical power of prescription is plus. It is a figure which shows the comparison with the conventional lens and the lens of this invention in the optical performance confirmation in case the spherical power of prescription is plus.

  The invention will now be described in conjunction with specific embodiments. Certain embodiments serve to provide a better understanding to those skilled in the art, but are not intended in any way to limit the scope of the invention as defined by the appended claims. In particular, the embodiments described independently throughout this specification can be combined to form further embodiments to the extent they are not mutually exclusive.

  FIG. 2 schematically illustrates a horizontal cross-sectional view of a double-sided aspheric single focus lens according to an embodiment of the present invention. The surface shown in FIG. 2 may be either the front surface or the rear surface of the lens. The front surface is defined as the side facing the object and the back surface is defined as the side facing the eye.

  The first horizontal cross section at the first height H1 represents a circular arc (surface) A1 having a first center C1. The second horizontal cross section at the second height H2 represents a circular arc (plane) A2 having a second center C2. Therefore, the surface is spherical in the horizontal direction. Further, the first center C1 and the second center C2 are on the same vertical line L. That is, the first horizontal cross section and the second horizontal cross section are coaxial in the vertical direction.

  The first height H1 may correspond to the upper region of the lens in the upper hemisphere of the lens. The first height H1 can be anywhere in the upper hemisphere, but taking into account the general vertical frame size, it is located between +2 mm and +10 mm from the horizontal centerline of the lens through the geometric center of the lens. obtain. The upper hemisphere has a spherical surface in the horizontal cross section. In FIG. 2, a thin solid line A1 represents a horizontal sphere in the upper region of the lens.

  The second height H2 may correspond to the lower region of the lens in the lower hemisphere of the lens. The second height H2 can be anywhere in the lower hemisphere, but taking into account the general vertical frame size, it is -6mm to -15mm from the horizontal centerline of the lens through the lens geometric center. May be located. In FIG. 2, a dotted line A2 represents a horizontal sphere in the lower region of the lens.

  Therefore, the surface A1 of the upper region of the lens is rotationally symmetric with respect to the vertical line L. In other words, the upper region of the lens is spherical in the horizontal direction. Thereby, the precision of a blocking process can be improved.

  The surface A2 in the lower region of the lens is also rotationally symmetric with respect to the vertical line L. The thin dashed arrows represent the normal vectors of both the upper and lower regions of the lens at specific positions in the upper region of the lens. (The normal vectors of the upper area of the lens and the lower area of the lens overlap.)

  The normal vector V1 of the far sphere at a specific position in the lower region of the lens is the same as the normal vector V2 of the near sphere at a specific position in the lower region of the lens. Therefore, unnecessary prisms do not occur at specific positions in the lower region of the lens.

  FIG. 3 schematically shows a vertical cross-sectional view of a double-sided aspheric single focus lens according to an embodiment of the present invention.

  The vertical cross section may include an aspherical first arc. The first arc of the vertical cross section may correspond to the lower region of the lens in the lower hemisphere. Therefore, the lower region of the lens is aspheric in the vertical direction.

  Also, the upper and lower hemispheres are spherical in the horizontal direction according to the present invention. With this feature, the stability of the lens position (posture) can be maintained when the lens is blocked with respect to the processing machine for surface processing.

  With the above design of the lens of the present invention, a double-sided aspheric single focus lens can be manufactured decentered. Since the lens can be decentered and reduced in size, the manufacturing cost can be reduced. Furthermore, it is not necessary to prepare many semi-finished lenses during manufacture. This also improves manufacturing efficiency.

  FIG. 4 shows a flowchart of the manufacturing process of a double-sided aspherical single focus lens according to the present invention.

  In step S1, the first and front surfaces of the lens are designed. In the present invention, different aspherical amounts are given to the upper and lower hemispheres in the longitudinal section from the optical center to the outer periphery of the lens. On the other hand, in the conventional lens, the distribution of the aspheric amount along the dividing line from the optical center to the outer periphery of the lens is uniform in the radial direction. This means that aspheric amounts on concentric circles equidistant from the optical center are equal.

  In step S2, the obtained optical performance is confirmed by, for example, an average power map and an astigmatism map. If the optical performance is good, the manufacture of the first surface is complete. If the optical performance is not good, the process returns to step S1.

  In step S3, the second and rear surfaces are then designed.

  In step S4, the obtained optical performance is confirmed. If the optical performance is good, the production of the second surface is complete. If the optical performance is not good, the process returns to step S3.

  FIG. 5 shows a vertical curve along the meridian according to the invention. Determining the vertical curve along the meridian has the same meaning as determining the aspheric shape along the meridian. In FIG. 5, the vertical axis indicates the position (mm) on the meridian. The horizontal axis shows the vertical curve (D). In this embodiment, NBC 4.00 is used as the base curve. The base curve is the front curve to provide the prescription. In the present invention, the meridian is defined as a line of intersection between the lens and a plane including the optical axis of the lens.

  In FIG. 5, the graph shows that the lens is aspherical toward the periphery of the lens. The aspheric shape is determined based on the prescription. In the case of a minus lens, the aspheric shape is smaller than the base curve, and in the case of a plus lens, the aspheric shape is larger than the base curve.

  Examples 1 to 4 FIGS. 6 to 9 exemplarily show how the optical performance is confirmed. The top row is for the embodiment and the bottom row is for the conventional. The three maps on the left side of each column are front maps, and the three maps on the right side of each column are rear maps. For the confirmation, the sagittal height map HT, the average power map MP, and the astigmatism map AS are used for the front surface and the rear surface. The contour lines of the map HT are drawn at a 0.25 mm pitch, and the maps MP and AS are drawn at a 0.25D pitch. The diameter of each map is 60 mm (60 phi). According to the front average power map and astigmatism map of the present invention, the power change is parallel to the horizontal line, that is, the horizontal cross section has a spherical shape.

  This means that the double-sided aspherical lens of the present invention has a high tolerance for misalignment in the horizontal direction between the front surface and the rear surface. Further, the order of decentration is acceptable, and the same optical performance can be maintained even if the amount of decentration is different.

  On the other hand, in the conventional double-sided aspherical lens, since the horizontal frequency distribution of the front surface is fixed, the same optical performance cannot be guaranteed by the alignment of the rear surface.

6 (a1), FIG. 7 (a1), FIG. 8 (a1), and FIG. 9 (a1) are for the front surface of the lens of the present invention. 6 (a2), FIG. 7 (a2), FIG. 8 (a2), and FIG. 9 (a2) are for the rear surface of the lens of the present invention. 6 (b1), FIG. 7 (b1), FIG. 8 (b1), and FIG. 9 (b1) are for the front surface of a conventional lens. 6 (b2), FIG. 7 (b2), FIG. 8 (b2), and FIG. 9 (b2) are for the rear surface of the conventional lens. The conditions of FIGS. 6 to 9 are shown in the following table.
NBC is an abbreviation of Nominal Base Curve (nominal base curve), and is a base curve converted with a standard refractive index of 1.50.

Claims (7)

A spectacle lens comprising a front surface and a rear surface, wherein the front surface is on the object side, and the rear surface is on the eye side;
The first horizontal cross section at the first height (H1) represents a circular arc (A1) having a first center (C1);
The second horizontal cross section at the second height (H2) represents a circular arc (A2) having a second center (C2);
The eyeglass lens, wherein the first center (C1) and the second center (C2) are on the same vertical line (L).   The first height (H1) corresponds to the upper region of the lens in the upper hemisphere of the lens, and the second height (H2) corresponds to the lower region of the lens in the lower hemisphere of the lens. Corresponding spectacle lens according to claim 1.   The spectacle lens according to claim 1, wherein the vertical line (L) is a rotation axis of a rotationally symmetric body.   The spectacle lens according to any one of claims 1 to 3, wherein the vertical cross section includes an aspherical first arc. A method for manufacturing a spectacle lens comprising a front surface and a rear surface, wherein the front surface is on the object side, and the rear surface is on the eye side,
Providing a first horizontal cross section at a first height (H1), wherein the first horizontal cross section represents a circular arc (A1) having a first center (C1);
Providing a second horizontal cross section at a second height (H2), the second horizontal cross section representing a circular arc (A2) having a second center (C2). ,
The method for manufacturing a spectacle lens, wherein the first center (C1) and the second center (C2) are on the same vertical line (L).   The first height corresponds to an upper region of the lens in the upper hemisphere of the lens, and the second height corresponds to a lower region of the lens in the lower hemisphere of the lens. A method for producing the spectacle lens according to 1.   The method for manufacturing a spectacle lens according to any one of claims 5 to 6, wherein the vertical cross section comprises a first arc of aspheric shape.