JP5083634B2 - Progressive power lens - Google Patents

Description

  The present invention relates to a progressive power lens used for glasses for presbyopia correction.

Presbyopia is a condition in which the ability of the eye to adjust with the lens decreases and the near vision is difficult. Progressive power lenses are used in the glasses for correcting presbyopia.
In general, a progressive-power lens is an aspherical lens having two refractive regions having different refractive powers and a progressive zone region in which the refractive power (power) changes progressively between these two regions. There is no border and it is possible to see from near to far with a single lens. Here, the two regions are two regions, a distance portion region set at an upper position of the lens and a near portion region set at a lower position of the lens. Progressive zone regions, which are transition zones between the distance portion region and the near portion region, are connected smoothly and continuously.
The far-field area is an area mainly for viewing an object at a long distance, the near-field area is an area for mainly viewing an object at a short distance, and the progressive zone area is mainly an eye for an object at a medium distance. It is an area for. However, since the refractive power of the progressive-power lens changes continuously, these regions are not clearly defined.
Here, the concept of distance, such as perspective, is not well-defined and has not been defined. In general, the long distance means a distance longer than 4 to 5 m, the short distance means the near side of 50 cm, and the middle distance means an intermediate distance between them.

By the way, it is not actually possible to design a multi-purpose lens in which a progressive power lens can clearly see objects at all distances. Designed so that it can be clearly seen for a specific distance, such as designing with emphasis on good visibility over a wide range according to the purpose or conversely focusing on good visibility over a wide range. It is something to do.
In lens design, how to change the refractive power on the main gaze from the distance area to the near area, that is, the addition gradient, and how to set the power distribution and aberration distribution in the horizontal direction from the main gaze. Depending on the situation, the lens required by the wearer is designed.
Patent Document 1 is given as an example of a lens designed in consideration of wearing from a long distance to a short distance (hereinafter, such a lens is referred to as a progressive lens).
Further, Patent Document 2 and Patent Document 3 are given as an example of a lens designed in consideration of wearing at a medium distance to a short distance (hereinafter, such a lens is referred to as a medium-progressive lens).
Further, Patent Document 4 and Patent Document 5 are given as examples of a lens designed in consideration of wearing at a short distance (hereinafter, such a lens is referred to as a near progressive lens).

The perspective progressive lens is a progressive power lens that gives a characteristic that is easy to see on average for all distances, basically correcting the distance vision while eliminating inconvenience at hand. By the way, in the business scene (office work), there are many cases of working at a short distance while sitting at a desk, but even when saying "working at a short distance" in a word, a newspaper spread out at hand. There is a difference in viewing distance between reading (hereinafter referred to as hand work) and working while viewing a display screen of a personal computer (PC: hereinafter referred to as PC) (hereinafter referred to as PC work). Further, the PC work often uses the upper part of the lens as compared with the hand work, and the position of the line of sight passing through the lens is different from that in the hand work. For this reason, as a result of taking into consideration the way of viewing at a long distance, the perspective progressive lens may be inconvenient when there is a difference in the distance of the visual target within the short distance.
For example, when it is considered to move the line of sight when moving from the hand work to the PC work, the object distance is generally longer in the PC work than in the hand work. The power required for the PC work varies slightly depending on the distance and near power of the lens wearer, the remaining adjustment power, the posture during the PC work, etc., but it is about -0.75D far from the near power at hand. The visible lens position is important. FIG. 8 is an explanatory diagram for explaining the relationship between the intermediate distance existing in the progressive region in the perspective progressive lens and the amount of rotation of the eyeball. Compared to the case where the addition is as small as 1.25D as shown in the center diagram of FIG. 8, when the addition is as large as 3.00D as shown on the right side, the PC screen can be focused from the hand. The possible eye rotation angle is reduced. In other words, even if the eyes are rotated upward to look at the PC screen from the focused state while looking at the hand, the focused area corresponding to the distance is narrow, making it difficult to see the PC screen.
On the other hand, when moving from a state of looking far away to the PC work, the eyes are turned largely downward to the lower position of the progressive area corresponding to the PC screen direction, or the PC screen direction is viewed with an unnatural posture with the jaw raised. There is a need. In other words, the perspective progressive lens becomes inconvenient and difficult to use as the addition increases in both cases of shifting from the state of looking at the near portion to the PC work or moving from the state of looking at the distant portion to the PC work. .
Further, since the lateral width of the clear vision region is generally narrowed as the addition is increased, the perspective progressive lens with such a narrow progressive region is also inconvenient.

In order to solve this problem, a medium progressive lens as described in Patent Documents 2 and 3 is convenient. Alternatively, a progressive lens as described in Patent Documents 4 and 5 is convenient.
The middle and near progressive lens is a lens in which the middle portion is stretched by moving the distance portion area of the perspective progression to a position higher than the perspective progression. Further, the progressive lens is a lens obtained by further removing the distance portion area of the lens from the lens. In many cases, the near-use part of the progressive lens brings the near-use part upward compared to the perspective-progressive lens and the mid-progressive lens so that the near part can be seen even if the rotation angle of the eye is small. FIG. 9 is an explanatory diagram for explaining the relationship between the intermediate distance existing in the progressive region in the medium-to-neighbor progressive lens and the amount of rotation of the eyeball, and FIG. 10 is the intermediate distance existing in the progressive region in the progressive lens and the amount of rotation of the eyeball. It is explanatory drawing explaining the relationship. The medium and near progressive lenses have a large progressive area for viewing the intermediate distance, so the progressive area for viewing the PC working distance from the hand distance is extremely narrow even when the addition is larger than the perspective and progressive lenses. There is no. Further, in a progressive lens, the progressive area for viewing the hand distance is reduced by removing the distance portion area from the lens to reduce the addition power. Accordingly, since the power range that has changed by about -0.75D from the near power used in the PC work that is substantially necessary for the PC work can be widened in the vertical direction of the lens, the desk work like the PC work can be performed. Can be comfortable.

Japanese Patent No. 3787227 JP 2008-65358 A Japanese Patent No. 2861892 JP 2004-191757 A Japanese Patent Laid-Open No. 9-251143

However, for example, when considering a lens in a business scene, although the desk work is comfortable with the near-neighbor progressive lens and the near-neighbor progressive lens, first, as shown in the left diagram of FIG. Since the lens area will be located quite above the lens, you will not be able to see the distance unless you pay attention to the upper part of the lens. In some cases, if the lens is placed in the glasses frame, the necessary distance area will be cut off. There is also a possibility of end. Also, in the near future, there is no distance area in the progressive lens. For this reason, a progressive lens cannot be used in the near future by a wearer who requires the distance portion area.
For this reason, it is necessary to change glasses when desk work is performed in a business scene, for example, when eating lunch outside the office or when it is necessary to look far away. That is, the conventional lenses such as the perspective progressive lens, the middle progressive lens, and the near progressive lens are not always satisfied with a single eyeglass in the life pattern such as a business scene. Therefore, there has been a demand for a progressive-power lens that can comfortably carry out the work from the hand to the PC while taking the style of a progressive lens, and can go out as it is and look far away without paying attention.
The present invention has been made paying attention to such problems existing in the prior art. The object is to provide a progressive-power lens that is comfortable to wear at an intermediate distance that is relatively close to a short distance, and that is comfortable to view far away.

In order to solve the above-mentioned problem, in the invention of claim 1, the distance portion area for viewing a relatively far distance disposed above the lens and the distance portion area disposed below the distance portion area. A near-field region having a large refractive power and a progressive zone region in which the refractive power is progressively changed between these regions, and the addition power is gradually added from the far-field region to the near-region region. In the progressive-power lens design method in which the addition gradient is set to be performed, the distance measurement position for measuring the lens power in the distance portion region and the near-field measurement for measuring the lens power in the near portion region The gist is that the distance from the position is set to 17 to 25 mm, and the addition ratio A (%) at the distance entrance is represented by the following relational expression.

The invention of claim 2 in addition to the structure of the invention according to claim 1, far entrance to that it has to match the distance eye point and its gist.
Further, in the invention of claim 3, in addition to the structure of the invention of claim 1 or 2, the addition ratio B (%) at a position 8 mm below the distance eye point is expressed by the following relational expression: To do.

In addition, in the invention of claim 4, in addition to the configuration of the invention of claim 3, the lens power at a position 8 mm below from the distance eye point is
(Lens power in the near area) -0.75D
The gist is that the frequency is set to a larger frequency.
The gist of the invention of claim 5 is that the following relational expression is used in place of the relational expression of claim 3 in the configuration of the invention of claim 3 or 4.

  The gist of the invention of claim 6 is that the following relational expression is used instead of the relational expression of claim 1 in the configuration of the invention of any one of claims 1 to 5.

The gist of the invention of claim 7 is that, in addition to the configuration of the invention of any of claims 1 to 6, the distance between the distance measurement position and the near measurement position is 20 to 23 mm. .
Further, in the invention of claim 8, in addition to the configuration of the invention of any one of claims 1 to 7, there is a difference between the distance power measured at the distance measurement position and the distance power measured at the near measurement position. The gist is that it is 1.50D (diopter) or more and 2.50D or less.

In the above configuration, in the progressive addition lens in which the addition gradient is set so that the addition is gradually added from the distance portion region to the near portion region, the distance measurement position and the near measurement position are The interval is set to 17 to 25 mm, and the joining ratio at the far entrance (which is also an intermediate entrance) is set based on the relational expression (1).
The relational expression (1) is an expression for setting the addition ratio at the distance entrance with respect to the length of the progressive zone within a suitable range. In an actual progressive-power lens, the length of the progressive zone varies depending on the wearer. Therefore, the addition ratio is varied using the length of the progressive zone in an actual progressive-power lens as a parameter. The recruitment ratio is the ratio of the recruitment amount at that position (here, the distance entrance) to the total recruitment amount.
According to the relational expression of Equation 1, for example, if the progressive zone length is 11 mm, the joining ratio at the far entrance is 16 to 23%. Further, if the progressive zone length is 15 mm, the joining ratio varies from 14 to 21%.
More preferably, the joining ratio at the far entrance is set based on the relational expression of the above equation (4). If the joining ratio at the far entrance conforms to the relational expression of Equation 4, it is possible to make the joining ratio more suitable for the PC work. If the recruitment amount at the distance entrance is too small, it will not be possible to bring in sufficient addition to the PC distance while maintaining a good optical balance of the entire lens, and if the recruitment amount at the distance entrance is too large, This is because there is an obstacle to the front view in the distance portion area.
With such a setting, it is possible to extend the progressive zone so that it is easy to visually check the intermediate distance that is relatively close to the short distance without moving the distance portion area upward. Become.

In the present invention, the distance measurement position is set approximately 4 to 6 mm above the distance entrance, and the near measurement position is set approximately 3 to 4 mm below the near entrance. In a progressive-power lens, a progressive zone is provided from the distance region to the near region, and the addition varies, but the connection between the distance region and the near region and the progressive zone is discontinuous. Designed to be introduced gently so as not to become. Therefore, the distance area or the near area is not a uniform frequency, but there is a slight addition gradient in the area close to the progressive zone, and it is originally set at a position including such an addition gradient. The lens power cannot be measured. Therefore, the distance measurement position and the near measurement position are set as described above as positions where a stable lens power without an addition gradient can be measured. In the present invention, since the distance between the distance measurement position and the near measurement position is set to 17 to 25 mm, the distance between the distance area and the near area is not as far as that of the middle and near progressive lenses.
Here, it can be said that the distance entrance (and near entrance) is a position where the refractive power (frequency) that is gradually added reaches the refractive power of the distance area (and near area) theoretically. However, as described above, in an actual lens design, the refractive power cannot be changed suddenly at the entrance as a discontinuous, for example, bent step. In other words, since the lens surface must be gently introduced into the distance portion region (and the near portion region), the change of the power becomes gentle near the entrance (more preferably, the change rate of the power gradient is constant). As designed).
For this reason, as shown in the addition curve of FIG. 11, if a certain point is assumed to be an entrance, it can be said that the point has not yet reached a predetermined distance (or near) frequency. Conversely, it can be considered that the distance entrance is in a state of being slightly added relative to the lens power in the distance area.

  The distance entrance is a virtual point on the main line of sight that shifts from the distance portion to the middle portion, and it is assumed that the distance is viewed above the lens from the distance entrance when the lens is worn. And design. The near entrance is a virtual point that shifts from the middle part on the main line of sight to the near part, and it is assumed that the near part is nearer than the near entrance when the lens is worn. Design. The length from the distance entrance to the near entrance (vertical difference length) is called the progressive zone length.

  In the progressive-power lens having such a setting, the distance entrance preferably coincides with the distance eyepoint. For example, in the medium-to-neighbor progressive lens, the distance entrance is arranged at a position considerably above the distance eye point. In this way, the distance entrance region is biased upward by matching the distance entrance with the distance eye point. Nothing will happen. Matching is a concept that includes a case where there is a substantial coincidence slightly shifted.

In the present invention, it is preferable that the addition ratio at a position 8 mm below the distance eye point is expressed by the relational expression of the above formula 2. The relational expression 2 is an expression for setting the addition ratio at a position 8 mm below the distance eye point with respect to the length of the progressive zone within a suitable range. In an actual progressive-power lens, the length of the progressive zone is Since it varies depending on the wearer, the addition ratio is varied using the length of the progressive zone in the actual progressive-power lens as a parameter. Generally, when looking at the hand naturally from the front, it is supposed to face downward by about 20 degrees. Since 20 degrees corresponds to about 9 mm below the distance eye point, the position 8 mm below the distance eye point is an important position when using a little above the lens even in near field work such as PC work.
According to the relational expression (2), for example, if the progressive zone length is 13 mm, the joining ratio at a position 8 mm below the distance eye point is 61 to 68%. Moreover, if the progressive zone length is 15 mm, the joining ratio will vary from 57 to 64%.
More preferably, the addition ratio at a position 8 mm below the distance eye point is set based on the relational expression of Equation 3 above. If the joining ratio at a position 8 mm below the distance eye point follows the relational expression (3), it is possible to make the joining ratio more suitable for PC work.
Furthermore, it is more preferable that the lens power at a position 8 mm below the distance eye point is set to be 0.75D or less smaller than the lens power in the near portion area. The power required for the PC work varies slightly depending on the distance and near powers of the lens wearer, the remaining adjustment power, the posture at the time of the PC work, and the like. A lens power larger than that is generally optimum for the distance when the PC work is performed. Accordingly, at a position 8 mm below the distance eye point, the lens power is set to be −0.75 D or smaller from the lens power in the near area, so that a more suitable focus is achieved by the PC work.

  In the inventions of the above-mentioned claims, it is possible to provide a progressive power lens that can cover all of a long distance to a short distance and is comfortable to wear at an intermediate distance that is relatively close to a short distance.

The figure which laid out the main data of the progressive-power lens in Example 1 of this invention. In Example 1, (a) is a figure which shows frequency distribution, (b) is a figure which shows astigmatism distribution, (c) is an addition curve. In Example 2, (a) is a figure which shows frequency distribution, (b) is a figure which shows astigmatism distribution, (c) is an addition curve. The figure which laid out the main data of the progressive-power lens in Example 2 of this invention. In Example 3, (a) is a figure which shows power distribution, (b) is a figure which shows astigmatism distribution, (c) is an addition curve. In Comparative Example 1, (a) shows a power distribution, (b) shows an astigmatism distribution, and (c) shows an addition curve. The addition curve in the comparative example 2. Explanatory drawing explaining the relationship between the progressive zone of a perspective progressive lens, and the amount of rotation of an eyeball. Explanatory drawing explaining the relationship between the progressive zone of a middle and near progressive lens, and the amount of rotation of an eyeball. Explanatory drawing explaining the relationship between the progressive zone of a progressive lens, and the amount of rotation of an eyeball soon. The conceptual diagram explaining the frequency measurement point and entrance for distance and near.

   Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the following description, only one lens is illustrated for the sake of explanation, but the other lens in the pair is formed symmetrically.

Example 1
The main data of the progressive-power lens 1 of Example 1 is as follows.
Distance power: S-0.00D C-0.00D
Addition: 2.00D
Progressive zone length 13mm
Center thickness: 2.0mm
Participation ratio in the distance eye point: 20.5%
Participation rate 8mm below distance eye point: 62.5%
Distance entrance: 2mm above geometric center Position near entrance: 11mm below geometric center Inset: 2.3mm

In the first embodiment, the lens is designed according to the layout of main points as shown in FIG. In the figure, O is the geometric center, E1 is the distance eye point, E2 is the near eye point, P1 is the distance entrance, Q1 is the near entrance, P2 is the distance power measurement position, Q2 is the near power measurement position, I is the inset amount.
Here, the distance eye point E1 is a position where a horizontal line (that is, a line of sight) passing through the center of the pupil passes when the wearer views the front. Since the first embodiment is a perspective progressive lens, the distance eye point E1 substantially coincides with the distance entrance P1.
In Example 1, the distance power measurement position P2 was set 6 mm above the distance entrance P1 (distance eye point E1).
In Example 1, the near entrance Q1 was set 13 mm below the far eye point E1 (distance entrance P1). The near entrance Q1 coincides with the near eye point E2. Therefore, the progressive zone length of Example 1 is 13 mm. The near eye point E2 is a position through which a horizontal line (that is, a line of sight) passing through the center of the pupil passes when the wearer views the hand position. The near vision frequency measurement position Q2 was set 3 mm below the near entrance Q1. The distance between the distance power measurement position P2 and the near power measurement position Q2 is 22 mm.

  Inset means that the position through which the horizontal line passing through the center of the pupil passes from the distance vision state to the near vision state is displaced, and the inset amount I is the amount of displacement. The measured value is obtained as a horizontal displacement amount in a range from the far eye point E1 to the near eye point E2. The inset amount I may be fixed at several sizes within a range of 2 to 3 mm on the assumption of a general user, and may be set based on the wearer's personal data. In Example 1, the inset amount I was set to 2.3 mm.

In the progressive-power lens 1 in Example 1 designed based on the data and layout as described above, a power distribution characteristic diagram and an aberration distribution characteristic diagram as shown in FIGS. 2A and 2B were obtained. As shown in the addition curve in FIG. 2 (c), in the first embodiment, the joining rate at the far entrance P1 (far eye point E1) is 20.5%, and the joining rate at the near entrance Q1 is 86. 0.0%. Further, the joining ratio at the position of 8 mm downward from the far entrance P1 (distance eye point E1) is 62.5%. The joining ratio at the far entrance P1 (far eye point E1) and the joining ratio at a position 8 mm below the far entrance P1 (far eye point E1) satisfy Expressions 1 and 2, respectively.
In general, when looking at the hand naturally from the front, it is supposed to face down 20 degrees. Since 20 degrees corresponds to about 9 mm below the EP, this lower 8 mm position is an important position when using a little above the near-field area of the lens, such as PC work. In the first embodiment, this lower 8 mm position is also a position (1.25 D in the first embodiment) where the addition power is −0.75 D from the lens power in the near portion area. In general, a lens power of −0.75 D or larger than the lens power in the near area is optimum for the distance when the PC work is performed. That is, in the first embodiment, the joining ratio at the optimum position for the PC work is optimum.

Next, comparison is made with the conventional perspective progressive lens 5 (Comparative Example 1) having the same addition power (2.0D) and the same progressive zone length (13 mm) as the perspective progressive lens 1 of Example 1 having such a configuration. To do.
First, regarding the frequency distribution, in FIG. 2A of Example 1 and FIG. 6A of Comparative Example 1, in Example 1, the change in addition from the distance entrance P1 to the near entrance Q1 is almost constant. Recognize. On the other hand, in Comparative Example 1, the joining ratio at the far entrance P1 (far eye point E1) is 7.0%, and the joining slope near the far entrance P1 is gentler than that in the first embodiment. However, in Comparative Example 1, it can be seen that there is a large change in addition in the region below the progressive zone.
On the other hand, regarding the aberration distribution, it can be seen from the comparison between FIG. 2B and FIG. 6B that the clear vision width from the intermediate portion to the near portion is wider in the first embodiment.
Further, the joining ratio at the position of 8 mm downward from the distance eye point E1 is 62.5% in the first example, whereas it is 53.5% in the first comparative example. That is, since the addition at this position is only 1.07D in Comparative Example 1, the addition in the direction of the line of sight that facilitates the PC work is insufficient. Originally, it is optimal that this position is a lens power of 1.25D from 2.00D to −0.75D in the near-field area or a lens power of the same as in the first embodiment. In Comparative Example 1, the position of 1.25D is 9.2 mm downward from the distance eye point E1 as shown in FIG. Accordingly, since the frequency at which the PC work is easy is considerably lower, the wearer needs to rotate the line of sight to this position as compared with the first embodiment. In addition, an unnatural posture in which the chin is raised to pass the line of sight is forced.

(Example 2)
The main data of the progressive addition lens 2 of Example 2 is as follows.
Distance power: S-0.00D C-0.00D
Addition: 2.00D
Progressive zone length 13mm
Center thickness: 2.0mm
Participation rate in the distance eye point: 16.5%
Participation rate 8mm below distance eye point: 62.5%
Distance entrance: 2mm above geometric center Position near entrance: 11mm below geometric center Inset: 2.3mm

The second embodiment is a progressive addition lens 2 having the same addition power (2.0D) as the first embodiment and the same progressive zone length (13 mm), and the layout is the same as that of FIG. is there. Contents common to the first embodiment are omitted.
In Example 2, the progressive-power lens 2 has a power distribution characteristic diagram and an aberration distribution characteristic diagram as shown in FIGS. 3 (a) and 3 (b). As shown in the addition curve in FIG. 3C, in the second embodiment, the joining rate at the far entrance P1 (far eye point E1) is 16.5%, and the joining rate at the near entrance Q1 is 87. .5%. Further, the joining ratio at the position of 8 mm downward from the far entrance P1 (far eye point E1) is 63.5%. The lens power at the position of 8 mm below is 1.27 D, which is slightly larger than the near power -0.75 D required for the PC work distance.
In Example 2, the joining rate of the distance entrance P1 was slightly lowered as compared with Example 1, and the joining rate 8 mm below the distance eye point and the joining rate of the near entrance were slightly raised. In this way, it is possible to adjust the balance of the addition ratio of the distance and the distance, but if the addition ratio of the distance eye point is made too small, the middle part becomes disadvantageous and the balance of the entire lens is lost. It is necessary to satisfy the condition of 1. In the second embodiment as well, the joining ratio at the optimum position for PC work is the optimum joining ratio, and the optimum lens power is set. Compared to Comparative Example 1, the point that the PC work is easy is the same as in Example 1.

(Example 3)
The main data of the progressive addition lens 3 of Example 3 is as follows.
Distance power: S-0.00D C-0.00D
Addition: 2.00D
Progressive belt length 11mm
Center thickness: 2.0mm
Participation rate in the distance eye point: 21.0%
Participation rate 8mm below distance eye point: 69.0%
Distance entrance: 2mm above the geometric center Position near entrance: 9mm below the geometric center

The third embodiment is a progressive addition lens 3 having the same addition power (2.00 D) as the first embodiment but having a different progressive zone length.
In the third embodiment, the lens is designed according to the layout of main points as shown in FIG. In the third embodiment, the distance eye point E1 substantially coincides with the distance entrance P1, and the distance power measurement position P2 is set 6 mm above the distance entrance P1 (distance eye point E1). The near entrance Q1 was set 11 mm below the distance eye point E1 (distance entrance P1). In the third embodiment, the near entrance Q1 coincides with the near eye point E2. The near vision frequency measurement position Q2 was set 3 mm below the near entrance Q1. The distance between the distance power measurement position P2 and the near power measurement position Q2 is 20 mm. The inset amount I is the same as in Example 1.
In the progressive-power lens 3 in Example 3 designed based on the above data and layout, the power distribution characteristic diagram and the aberration distribution characteristic diagram as shown in FIGS. 5A and 5B were obtained. As shown in the addition curve in FIG. 5C, in this third embodiment, the joining rate at the far entrance P1 (far eye point E1) is 21.0%, and the joining rate at the near entrance Q1 is 86. 0.0%. Further, the joining ratio at the position of 8 mm downward from the far entrance P1 (far eye point E1) is 69.0%.
Further, as shown in the addition curve of FIG. 5C, in Example 3, the position where the lens power in the near portion area is −0.75D is below the far entrance P1 (the far eye point E1). 7 mm. That is, at a position 8 mm downward from the distance entrance P1 (distance eye point E1), the lens power is 1.35D which is slightly larger than 1.25D which is a power obtained by subtracting 0.75D from the lens power in the near area. It is a value of the degree.

Next, it compares with the conventional perspective progressive lens 6 (comparative example 2) of the same addition (2.0D) and the same progressive zone length (11 mm) as the perspective progressive lens 1 of Example 3 of such a structure. To do.
The addition ratio at a position 8 mm downward from the distance eye point E1 is 69.0% in Example 3, whereas it is 60.0% in Comparative Example 2 as shown in the addition curve of FIG. . That is, since the addition at this position is about 1.2D in Comparative Example 2, it cannot be said that the addition in the line-of-sight direction in which the PC work is easy in this progressive zone length is necessarily sufficient. In Comparative Example 2, the position of 1.25D necessary for the PC work is a position of 8.5 mm downward from the distance eye point E1. Therefore, when the wearer wants to visually observe at this frequency, the wearer needs to rotate the line of sight down to a position of 8.5 mm, and is forced to take a posture with the jaw slightly raised to pass the line of sight.

It should be noted that the present invention can be modified and embodied as follows.
In each of the second embodiments, the layout is such that the distance entrance P1 and the distance eye point E1 match. However, a layout that does not match can also be adopted.
In the above embodiment, the case where the progressive zone length is 11 mm and 13 mm has been described as an example, but other progressive zone lengths may be used.
The positions of the distance power measurement position P2 and the near power measurement position Q2 are not limited to the above. If the distance between the two is 17 to 25 mm (more preferably 20 to 23 mm), the position may be appropriately changed.
-The joining ratio in the distance eye point and the joining ratio 8 mm below the distance eye point may be changed according to the degree of addition of the wearer. For example, in the progressive zone length of 13 mm, the addition ratio at the distance eye point may be appropriately changed to 18% when the addition is 1.50D, 21% when the addition is 2.50D, and the like.
In addition, it is free to implement in a mode that does not depart from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1-3 ... Progressive-power lens, E1 ... Distance eye point, P1 ... Distance entrance, P2 ... Distance measurement position, Q1 ... Near entrance, Q2 ... Near measurement position.

Claims (8)

A distance portion region for viewing relatively far away above the lens, a near portion region having a higher refractive power than the distance portion region disposed below the distance portion region, and these regions Progressive power having a progressive zone where the refractive power is progressively changed, and the addition gradient is gradually added from the distance area to the near area. In the lens design method ,
The distance between the distance measurement position for measuring the lens power of the distance portion area and the distance measurement position for measuring the lens power of the near area is 17 to 25 mm, and the addition ratio A at the distance entrance (%) design method of the progressive addition lens, wherein a is as shown by the following equation.

Design method of the progressive addition lens according to claim 1 is far inlet, characterized in that to match the distance eye point. Design method of the progressive addition lens according to claim 1 or 2, characterized in that the subscriber ratio B (%) is as shown by the following relational expression of 8mm lower position from the distance eye point.

The lens power at a position 8 mm below the distance eye point
(Lens power in the near area) -0.75D
4. The progressive-power lens designing method according to claim 3, wherein the power is set at a greater power. 5. The progressive power lens design method according to claim 3, wherein the following relational expression is used instead of the relational expression of claim 3.

6. The progressive power lens designing method according to claim 1, wherein the following relational expression is used instead of the relational expression of claim 1.

The method for designing a progressive-power lens according to claim 1, wherein an interval between the distance measurement position and the near measurement position is 20 to 23 mm. 8. The difference between the distance power measured at the distance measurement position and the distance power measured at the near measurement position is 1.50D (diopter) or more and 2.50D or less. A method for designing a progressive-power lens according to any one of the above.

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