JP2010085278A - Lens meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens meter capable of accurately measuring a progressive lens, prescribed with a horizontal prism and finding out the possibility of prescription of the horizontal prism for a lens. <P>SOLUTION: The lens meter includes a measuring optical system, capable of projecting a measuring light beam to a test lens and receiving the measuring light beam which has passed through the test lens, to measure an optical characteristic distribution at a plurality of measuring points; display means for displaying, in a screen a guide leading a measuring position to a distant portion of the progressive lens, based on the optical characteristics obtained in the measuring optical system, when the progressive lens is measured; a determination means for determining whether the horizontal lens is the prescribed horizontal prism, based on the astigmatic frequency distribution and prismatic distribution in the crosswise direction of the progressive zone of the progressive lens; a computation means for computing a crosswise position of the distant portion, based on a horizontal prismatic distribution in the progressive zone, when it is determined that the lens has been prescribed with the horizontal prism; and display control means for controlling the display of the guide according to a computed result by the computation means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a lens meter that measures optical characteristics of a lens to be examined.

There is a lens meter that projects a measurement light beam onto a test lens and receives a measurement light beam that has passed through the test lens with a light receiving element to obtain optical characteristics of the test lens. When measuring the lens with this lens meter, the examiner moves the test lens while looking at the alignment screen displayed on the display, and aligns the measurement position with the intended part of the test lens. In a mode for measuring the addition power of a progressive power lens (hereinafter referred to as a progressive lens), guide marks for guiding the measurement position to the distance portion and the near portion are displayed on the display. At the time of alignment of the progressive lens to the distance portion, the horizontal prism is set to a position where the horizontal prism is substantially 0 (in the case of a lens having astigmatism power, it is offset according to the astigmatism power and the astigmatic axis angle). A determination is made and a guide mark is displayed to guide the measurement position to that position.
JP-A-6-58842 JP-A-9-43101 JP 2003-75296 A

  However, when a spectacle wearer has an oblique position, when measuring a progressive lens in which a horizontal prism is prescribed to correct this oblique position, whether or not the conventional lens meter is a progressive lens in which the horizontal prism is prescribed. Was not considered. For this reason, the possibility that a horizontal prism is prescribed for the progressive lens may be overlooked.

  Further, in the case of a progressive lens for which a horizontal prism is prescribed, the position at which the conventional horizontal prism value is substantially 0 (in the case of a lens having an astigmatism power, the position is offset according to the astigmatism power and the astigmatic axis angle). In the method for determining as the distance portion, an error occurs in the determination of the distance portion. In particular, if the prescribed horizontal prism value is large, the error in determining the distance portion also increases. In this case, the position where the prism value in the horizontal direction is substantially 0 is a position shifted from the actual distance portion, and an accurate frequency of the distance portion cannot be obtained. When the measurement result of the distance portion is inaccurate, the addition power based on the position of the near portion and the power of the near portion that are measured thereafter is also incorrect.

  In view of the above-mentioned problems of the prior art, the present invention can know the possibility that a horizontal prism is prescribed for a progressive lens, and even with a progressive lens prescribed for a horizontal prism, more accurate measurement is possible. It is an object of the present invention to provide a lens meter that can obtain a result.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) A measurement optical system is provided that can project a measurement light beam onto a test lens, receive the measurement light beam that has passed through the test lens, and measure an optical characteristic distribution at a plurality of measurement points. In a lens meter that measures the addition of a progressive lens, the approximate center position of the progressive zone is determined based on the astigmatic power distribution in the horizontal direction of the progressive zone of the progressive lens, and based on the prism value obtained at the approximate central position of the progressive zone And determining means for determining whether or not the horizontal prism is a prescribed progressive lens.
(2) The lens meter of (1) is characterized by comprising determination result display means for displaying a result determined by the determination means that the horizontal prism is a progressive lens.
(3) In the lens meter of (2), alignment display means having a screen for displaying a distance portion guide for guiding the measurement position to the distance portion of the progressive lens at the time of measurement of the progressive lens, and horizontal by the determination means Display control means for controlling the display of the distance guide of the alignment display means based on the prism value at a substantially central position of the progressive zone when the prism is determined to be a prescribed lens, To do.
(4) In the lens meter according to (3), the display control means may be configured to guide the measurement position to a position where the prism value obtained by the measurement optical system becomes a prism value at a substantially central position of the progressive zone. The display of the part guide is controlled.

  According to the present invention, it is possible to know the possibility that a horizontal prism is prescribed for the progressive lens. Even with a progressive lens for which a horizontal prism is prescribed, a more accurate measurement result can be obtained.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic external view of a lens meter according to an embodiment. Reference numeral 1 denotes a lens meter main body. Reference numeral 2 denotes a display composed of a liquid crystal display or the like, which displays information necessary for measurement such as measurement results and alignment targets. Reference numeral 3 denotes an input switch unit. When a switch corresponding to the switch display displayed on the display 2 is pressed, necessary input instructions such as switching of the measurement mode are performed. Reference numeral 4 denotes a nose piece of a mounting member on which the test lens LE is mounted. Reference numeral 5 denotes a lens presser, and the lens LE placed on the nosepiece 4 can be stably held by lowering the lens presser.

  Reference numeral 6 denotes a lens table movable in the front-rear direction. In the measurement of the lens LE with a spectacle frame, the lower ends of the left and right frames (in this specification, the upper and lower parts of the spectacle frame and the lens means the upper and lower directions when the spectacles are worn Astigmatism axis angle measurement and progressive lens measurement can be performed accurately. Reference numeral 7 denotes a marking mechanism. Reference numeral 8 denotes a READ switch for reading the optical characteristic data of the lens LE. By pressing the switch 8, the measured value is held on the display 2, and the measured value is stored in the memory inside the apparatus.

  FIG. 2 is a schematic configuration diagram of the optical system and the control system. Reference numeral 10 denotes a measurement optical system, and L1 denotes its measurement optical axis. The measurement optical system 10 includes a measurement light source 11 such as an LED, a collimating lens 12, a mirror 13, a grid plate 14 that is a measurement index plate on which a measurement index is formed, and a two-dimensional light receiving sensor 15. The grid plate 14 is held by the holding member 16 of the main body 1, and the opening 4 a of the nose piece 4 is positioned on the grid plate 14. The opening 4a is circular with a diameter of 8 mm.

  FIG. 3 is a diagram showing an index pattern formed on the grid plate 14. The outer diameter of the grid plate 14 is formed to be slightly larger than the inner diameter of the opening 4 a of the nosepiece 4. The grid plate 14 is formed with a measurement index 20 having a geometric pattern for measuring the optical characteristic distribution of the lens in the opening 4a at a time without moving the lens by the examiner. In the measurement index 20 in this embodiment, a large number of circular holes are arranged in a lattice pattern. More specifically, the measurement index 20 includes a center hole 21 having a diameter of 0.4 mm formed at a center position through which the measurement optical axis L1 passes, and a large number of small holes having a diameter of φ0.2 mm arranged around the center hole 21. It consists of holes 22. The small holes 22 are distributed in a lattice shape at a pitch of 0.5 mm. The measurement index 20 is formed by applying a black Cr coat in which the holes 21 and 22 are whitened to the rear surface of the grid plate 14. The center hole 21 is a reference index for specifying the correspondence relationship of the other holes 21. That is, the center hole 21 is used as a reference index for identifying each dot image corresponding to the “0D reference” in which the lens LE is not placed on the optical path when the lens LE is placed. The The reference index is not limited to the center of the grid plate 14 as long as it can be distinguished from other measurement indexes, and may be in another location, and the number and shape thereof are not limited.

  The light beam from the measurement light source 11 is collimated by the collimating lens 12, reflected by the mirror 13, and projected onto the lens LE placed on the nosepiece 4. Of the light transmitted through the lens LE, the light beam that has passed through the holes 21 and 22 of the grid plate 14 enters the light receiving sensor 15.

  An output signal from the light receiving sensor 15 is input to the control unit 40. When the lens LE is not placed on the optical path, the control unit 40 uses the coordinate position of each dot image of each of the holes 21 and 22 incident on the light receiving sensor 15 as a reference, and the lens LE having a refractive power is placed. The optical characteristics (spherical power S, astigmatism power C, astigmatism axis angle A, prism value Δ) of the lens LE are calculated based on the positional changes of the dot images. For example, in a lens LE having only a spherical power, each dot image is displaced to a position enlarged or reduced to a circular equidistant from the optical center of the lens LE, when the lens LE is not placed on the optical path. Is done. The spherical power S is obtained based on the displacement of each dot image. Further, in the case of the lens LE having only the astigmatic power C, each dot image is enlarged or reduced in an elliptical shape in a direction perpendicular to the astigmatic axis of the lens LE, compared to the case where the lens LE is not placed on the optical path. The position is displaced. Astigmatism power C and astigmatism axis angle A are obtained based on the displacement of each dot image. The prism value Δ is obtained from the amount of parallel movement of the dot image of the hole 21 of the grid plate 14 or the dot image in the vicinity thereof. A lens having a spherical power, an astigmatic power, and a prism may be considered as a composite of these.

  The optical characteristics of the lens LE are calculated with four adjacent (at least three) dot images as one set. Alternatively, the dot characteristics of 3 × 3 points, 4 × 4 points, 5 × 5 points, etc. may be taken as one set, and the optical characteristics may be calculated from the average of the dot images. The measurement point in these cases is determined as the center position of a set of dot image ranges or the position of a specific dot image. The measurement position of the adjacent place is measured without reducing the resolution of the measurement position by using a set of dot images shifted by one dot. Accordingly, information on a plurality of measurement positions can be obtained at once in the nosepiece opening 4a, and an optical characteristic distribution in the nosepiece opening 4a can be obtained. For this reason, in the measurement of the progressive lens, the alignment state whether the current measurement position is in the progressive zone, the distance portion, or the near portion is efficiently detected. The control unit 40 also serves as a display control unit that controls display of the alignment screen of the display 2 based on the detection result of the alignment state. Further, the control unit 40 continuously obtains the optical characteristic distribution at predetermined time intervals based on the output of the light receiving sensor 15. Note that the current measurement position in the following description is used to mean the center position through which the measurement optical axis L1 passes among a plurality of measurement points in order to perform alignment with high accuracy. However, in the case where the optical characteristics can be obtained with an acceptable accuracy at other measurement points, the current measurement position includes a case where another measurement point is used.

  Next, in the lens meter having the above configuration, the alignment operation at the time of measuring the progressive lens will be mainly described. Hereinafter, a case where the right-eye lens is selected in the progressive lens measurement mode will be described.

  When the measurement mode of the progressive lens is set by the switch arranged in the switch unit 3, the alignment screen 2a of the display 2 displays the lens mark 100 having a progressive band graphic that makes the progressive lens image and the current measurement position. A cross line 101 is displayed (see FIG. 4A). The current measurement position is shown as the center position of the cross line 101. In the present embodiment, the lens mark 100 is moved and displayed with a change in the alignment state due to the movement of the lens LE. The center of the cross line 101 is fixed and displayed at the center of the screen 2a. In this apparatus, the upper direction of the display screen of the display 2 corresponds to the rear side of the renmeter body, and the lower direction of the screen corresponds to the front side of the lens meter body. When the lens LE is placed on the nosepiece 4, based on the optical characteristic distribution of a large number of points measured in the opening 4 a, the position where the measurement position is on the lens LE (rough alignment with the measurement optical axis L <b> 1). The state is determined by the control unit 40.

  The progressive lens is measured by first identifying the distance portion and measuring the distance portion power, and identifying the near portion after measuring the distance portion and measuring the near portion power. And obtaining the addition based on the power of the distance portion and the power of the near portion. In the step of specifying the position of the distance portion, in order to accurately specify the vertical position of the distance portion, the examiner first moves the lens from the progressive zone in the direction of no addition. In the measurement optical system of this apparatus, due to the configuration of the measurement index 20 arranged on the grid plate 14, the optical characteristics of the progressive zone can be measured at a time within a range of about 7 mm in the opening 4a without moving the lens.

  Whether or not the measurement position in the vertical direction of the lens LE is located in the progressive zone is determined from a change in the spherical power S (or equivalent spherical value SE) distributed in the vertical direction of the lens LE. When the change in the spherical power S distributed in the vertical direction is substantially zero, the measurement position may be located in the distance portion (or near portion). In this case, a guide arrow mark 120 for moving the lens to the front side of the lens meter main body is displayed on the screen as shown in FIG. 4B in order to guide the measurement position to the progressive zone. If the spherical power S distributed in the vertical direction of the lens increases in the downward direction of the lens, it is determined that the measurement position in the vertical direction of the lens is in the progressive zone.

  Here, conventionally, in order to guide the measurement position from the progressive zone to the distance portion, the horizontal direction is determined as a position where the horizontal prism value is substantially zero. When the lens has an astigmatism power C, the position at which the prism value in the left-right direction of the lens is 0 is on the astigmatism axis. In this case, the influence of the astigmatism power is offset from the prism value at the measurement position, and is corrected to a value indicating the amount of deviation and the direction of deviation from the longitudinal axis of the distance portion. The details of the method of determining the position of the distance portion by offsetting the influence of the astigmatism power C is incorporated in the description of JP-A-6-58842. However, if the eye of the spectacle wearer has an oblique position and a horizontal prism is added to the lens to correct this, the position where the measured horizontal prism is approximately zero is The added amount will be shifted to the left or right.

  Therefore, in this apparatus, when the measurement position is guided from the progressive zone to the distance portion, the horizontal prism is arranged on the lens depending on whether or not the horizontal prism is larger than the predetermined reference at the approximate left and right centers of the progressive zone. It is determined whether it is prescribed. For example, when the horizontal prism at the approximate center of the left and right of the progressive zone is 0.5Δ (prism value) or less, it is determined that the horizontal prism is not prescribed, and when it exceeds 0.5Δ (prism value). Is determined that a horizontal prism is prescribed. It should be noted that the prism value of this criterion can be determined in consideration of the fact that the horizontal band is shifted to the left and right from the position where the horizontal prism is substantially zero, depending on the inward amount (1-2 mm) of the near portion. preferable. The criterion prism value is corrected in proportion to the spherical power S of the lens.

  Whether or not the measurement position is at the approximate center on the left and right of the progressive zone is determined from the change in the astigmatic power C distributed in the left and right direction of the lens. The position deviated from the progressive zone in the left-right direction is an optically distorted portion, and is an area where the astigmatism power C is increased or decreased as compared to the progressive zone. Even in the progressive zone, the astigmatism power C is increased or decreased in the left-right direction. Therefore, the center position of the left and right of the progressive zone can be determined as the position where the absolute value of the astigmatism power C in the left-right direction is minimum. FIG. 5 is a distribution example of the absolute value of the astigmatism power C in the left-right direction of the lens across the progressive zone, and the position Pc where the absolute value of the astigmatism power C is minimum is determined as the substantially central position in the left-right direction of the progressive zone. Is done.

  In FIG. 5, whether the center of the measurement range T by the measurement index 20 is on the right side or the left side with respect to the position Pc is determined by the distribution of the astigmatism power C in the measurement range. If the measurement range T is on the left side of FIG. 5, the measurement position is also off the left side of the progressive zone. Therefore, as shown in FIG. 4C, a guide arrow mark 121 a that moves the lens to the left side of the lens meter body is provided. Is displayed. On the other hand, if the measurement range T is on the right side of FIG. 5, the measurement position is also off the right side of the progressive zone. Therefore, as shown in FIG. 4D, the guide arrow moves the lens to the right side of the lens meter body. A mark 121b is displayed. When the measurement position is located at the approximate center in the left-right direction of the progressive zone, the arrow mark 121a or 121b is erased, and the distance portion as a guide for guiding the measurement position to the distance portion as shown in FIG. The target 110 is displayed.

  Here, when it is determined that the horizontal prism is not prescribed in the determination of the presence / absence of the horizontal prism at the approximate center of the progressive zone, the measurement position is guided to the position where the horizontal prism is substantially zero as in the conventional case. The distance target 110 is displayed. On the other hand, if it is determined that the horizontal prism is prescribed, the distance target 110 for the cross line 101 and the measurement target are guided to the position where the prism position is obtained at the approximate center position Pc of the progressive zone. The guide display of the lens mark 100 or the like is controlled.

  For example, from the measurement result of the optical property distribution in the progressive zone, it is assumed that the astigmatism power C of the lens is substantially 0 (assumed to be a lens having only spherical power), and the prism at the approximate center position Pc of the progressive zone is 2Δ. Suppose that the base direction of the prism is the left side. In this case, the distance portion is assumed to be on the right side by 2Δ with respect to the position where the horizontal prism is substantially 0, and the distance portion target 110 and the lens mark 100 are displayed so as to guide the measurement position to that position. . That is, when it is determined that the horizontal prism is prescribed, the left and right position of the distance portion is assumed to be on the same vertical axis as the substantially central position Pc in the left and right direction of the progressive zone, and the guidance to the distance portion is performed. The display of the mark is controlled. When the lens has an astigmatism power, the effect of the astigmatism power is corrected as in the case where the horizontal prism is not prescribed as described above.

  The examiner moves the lens to the back side of the lens meter body so that the distance target 110 is aligned with the center of the cross line 101 in accordance with the display of FIG. In the display of FIG. 6A when the measurement position is guided from the progressive zone to the distance portion, an arrow mark 122 that guides the direction in which the lens should be moved is displayed in order to make the movement direction of the lens clearer. . In addition, as shown in FIG. 1, a message 130 indicating that there is a possibility that a horizontal prism is prescribed for the lens is displayed below the alignment screen 2 a of the display 2.

  Note that the determination of the possibility of prescribing the horizontal prism is a determination on the progressive zone, and therefore it is considered that measurement errors are included. For this reason, when the horizontal prism value is small (in the vicinity of 0.5Δ), the measurement position may not be displayed until it reaches the vicinity of the distance portion. The determination of whether or not the horizontal prism is prescribed is continuously performed until the measurement position reaches the distance portion. If the addition power (the change in spherical power S or equivalent spherical value SE) becomes smaller as the distance is closer, the measurement error with respect to the prescription of the horizontal prism is also reduced, and the determination accuracy is improved. As a result, when the possibility of prescribing the horizontal prism becomes low, the normal distance portion determination (method of determining the position where the horizontal prism is substantially 0 as the distance portion) is returned.

  After the distance target 110 shown in FIG. 6A is displayed, if the measurement position is shifted to the right with respect to the distance part, the lens with respect to the cross line 101 as shown in FIG. The mark 100 and the distance target 110 are displayed while being shifted to the left side, and an arrow mark 123a for guiding the movement of the lens to the right side is displayed. When the measurement position is shifted to the left side with respect to the distance portion, the lens mark 100 and the distance portion target 110 are shifted to the right side with respect to the cross line 101 as shown in FIG. , An arrow mark 123b for guiding the lens to the left is displayed. By displaying these guides, the examiner can accurately know the direction in which the lens should be moved.

  If it is determined that the measurement position has reached the distance portion, the distance portion target 110 is changed to a cross mark 112 with the center of the cross line 101 matched as shown in FIG. Thereby, the examiner can know that the alignment of the distance portion is completed. The vertical direction of the distance portion is determined as a position where the change in the spherical power S or the equivalent spherical value SE is almost eliminated, and the horizontal position is determined based on the prism value at the center of the left and right of the progressive body as described above. The

  When the alignment to the distance portion is completed and the READ switch 8 is pushed by the examiner, the optical characteristics (S, C, A, prism values) of the distance portion are stored in the memory 42. Alternatively, the optical characteristics of the distance portion are automatically stored in the memory 42, and the measured values of the distance portion are held and displayed on the display screen shown in FIG. At this time, as a result of determining that the horizontal prism is prescribed, the horizontal prism value is displayed in the display column 200.

  When the measured value of the distance portion is stored in the memory 42, the process proceeds to the measurement step of the near portion. As shown in FIG. 7A, on the screen 2a of the display 2, the cross mark 112 indicating completion of alignment of the distance portion is erased, and a new circular near portion is used as a guide for guiding the measurement position to the near portion. The part mark 114 is displayed so as to correlate with the progressive band graphic display of the lens mark 100. In addition, an arrow mark 124 that guides the lens to move toward the near side with respect to the lens meter main body is displayed in order to adjust the measurement position to the near portion. The examiner moves the lens so that the center of the cross line 101 faces the near portion mark 114.

  If the addition power (or SE value) detected at the measurement point in the vertical direction of the measurement range increases and becomes substantially constant at a certain point, it is determined that the vertical measurement position is in the near portion. If the optical distortion amount at the measurement position (the center of the measurement range) becomes the minimum value, it is determined that the left-right direction is also in the near portion. When it is determined that the measurement position has reached the near portion, the near portion mark 114 is changed to the display of the large cross 116 as shown in FIG. Thereby, the examiner can know the completion of the alignment to the near portion. When the examiner presses the READ switch 8, the measured value of the near portion is stored in the memory 42, and the addition power is displayed on the screen of the display 2. Alternatively, the measured value of the near portion is automatically stored in the memory 42 when the alignment of the near portion is completed.

  The display on the display 2 shown in FIG. 1 is a screen example after the measurement of the near portion is completed. As the measurement results of the right lens, the measurement results of the spherical power S, the astigmatism power C, and the astigmatism axis angle A of the distance portion are displayed in the display column 201, and the prism values of the distance portion are displayed in the display column 202. Is displayed in the display column 203. When it is determined that the lens is a prescription for a horizontal prism, a message 130 to that effect is displayed and, apart from the distance value prism value displayed in the display field 202, a prescription for the prescribed horizontal prism is displayed. The predicted value is displayed in the display column 200. The predicted value of the horizontal prism displayed in the display field 200 is the prism value predicted in the progressive zone.

  By guiding the distance portion as described above, when measuring a progressive lens prescribed with a horizontal prism, the alignment accuracy to the distance portion is improved compared to the conventional method, and the measured value of the distance portion is also accurate. can get. Then, the position of the near portion affected by the measured value of the distance portion is also determined with high accuracy, and the addition value becomes a more accurate value. In addition, the examiner can know the possibility of the prism prescription for the lens. For this reason, when prescribing spectacle lenses, it becomes possible to examine the necessity of an oblique inspection for spectacle wearers.

It is the external appearance schematic of a lens meter. It is a schematic block diagram of an optical system and a control system. It is a figure which shows the parameter | index pattern formed in the grid board. It is explanatory drawing about the alignment operation | movement at the time of the measurement of a progressive lens. It is an example of distribution of the absolute value of the astigmatism power in the left-right direction of the progressive zone. It is an example of a display in the case of guiding a measurement position to a distance part. It is an example of a display in the case of guiding a measurement position to a near portion.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens meter main body 2 Display 10 Measurement optical system 14 Grid board 40 Control unit

Claims (4)

The measuring optical system is equipped with a measuring optical system capable of projecting the measuring light beam onto the test lens, receiving the measuring light beam that has passed through the test lens, and measuring the optical characteristic distribution at a plurality of measurement points. In a lens meter that measures the addition power,
Whether the progressive lens is a progressive lens for which the horizontal prism is prescribed based on the prism value obtained at the approximate center position of the progressive band, based on the astigmatic power distribution in the left-right direction of the progressive band of the progressive lens. A lens meter, comprising: determination means for determining 2. The lens meter according to claim 1, further comprising determination result display means for displaying a result determined by the determination means that the horizontal prism is a progressive lens prescribed. 3. The lens meter according to claim 2, wherein an alignment display means having a screen for displaying a distance portion guide for guiding the measurement position to the distance portion of the progressive lens during measurement of the progressive lens, and a horizontal prism is prescribed by the determination means. And a display control means for controlling the display of the distance guide of the alignment display means on the basis of the prism value at the substantially central position of the progressive zone when it is determined that the lens is a lens. . The lens meter of claim 3,
The display control means controls the display of the distance guide so as to guide the measurement position to a position where the prism value obtained by the measurement optical system becomes a prism value at a substantially central position of the progressive zone. A lens meter.