KR20080080048A - Lens meter - Google Patents

Abstract

A lens meter is provided to improve stability and precision in measurement of optical characteristics of a lens. A lens meter comprises a measurement optical system(20), a calculation unit, and a display control unit. The measurement optical system includes a target panel having a plurality of measurement targets which are placed in a predetermined pattern around a measurement optical axis, and a photodetector which photo-receives a measurement light flux passing through the lens. The measurement targets have a first measurement target in a first region near the measurement optical axis, and a second measurement target in a second region outside the first region. The calculation unit calculating the optical characteristics includes a first calculation unit which calculates first optical characteristics of the lens based on a detection result of the first measurement target by the photodetector, and a second calculation unit which calculates second optical characteristics of the lens based on the detection results of the first measurement targets and the second measurement targets. The display control unit displays the second optical characteristics as the optical characteristics of the lens if one of the calculation result by the first calculation unit and the detection result by the photodetector satisfies a predetermined condition, and displays the first optical characteristics as the optical characteristics of the lens on a display unit if the predetermined condition is not satisfied.

Description

Lens meter {LENS METER}

The present invention relates to a lens meter for measuring the optical properties of the test lens.

The light beam is transmitted to the test lens, and the light beam passing through the test lens is detected by a light receiving element, and based on the detection result, the optical characteristics (sphere power (S), principal plane of the lens of the test lens) Lens meters having a measuring optical system for obtaining power (C) and astigmatic axial angle (A) are known. This type of conventional lens meter is based on the deviation of the measurement index detected by the light-receiving element based on the set of four measurement indexes (in principle, three measurement indexes) centered on the measurement optical axis. It was set as the structure which measures a characteristic (for example, refer Unexamined-Japanese-Patent No. 60-17335, US3880525 (Japanese Unexamined-Japanese-Patent No. 50-145249)). In addition, in order to easily measure the distribution of the optical characteristics of the lens to be examined and the far and near parts of the progressive lens, a large number of measurement indices arranged in the nosepiece are used. A lens meter is also proposed (see, for example, US6972837 (Japanese Laid-Open Patent Publication 2003-75296)). In any lens meter, since the influence of aberration increases as the measurement indicator moves away from the measurement optical axis, the measurement index arranged on a circumference of diameter 2-3 mm around the measurement optical axis basically. The measurement is performed using.

However, in the measurement based on the measurement index near the measurement optical axis, the measurement of the optical characteristic may be unstable due to the lens power and the lens surface state, and the reliability of the measurement accuracy may be inferior. That is, when the refractive power of the lens is a weak number, since the deviation of the index near the optical axis is small, the measured value tends to be unstable. In particular, in the case where the principal surface power is weak, the deviation of the principal surface axis angle due to it becomes large, the measurement result becomes unstable, and the measurement accuracy thereof deteriorates. In the measurement using the index near the measurement optical axis, the measured value is not stable even when there is a flaw or contamination in the measurement area, and the reliability of the measurement accuracy is inferior.

This invention makes it a technical subject to provide the lens meter which can acquire the optical characteristic of a lens stably and with high precision.

In order to solve the said subject, this invention is equipped with the following structures, It is characterized by the above-mentioned.

The lens meter for measuring the optical characteristics of the lens to be tested includes a measuring optical system (the measuring optical system includes a plurality of measurement indexes arranged in a predetermined pattern around the measurement optical axis (the measurement index is a first measurement in a first region close to the measurement optical axis). An indicator plate having an index, at least a second measurement index in a second region outside of the first region), a light receiving element for receiving a measurement light beam passing through the lens to be examined), and an optical characteristic Arithmetic means (the arithmetic means includes first arithmetic means for calculating a first optical characteristic of the lens based on a detection result of the first measurement index by the light receiving element, and a detection result of the first measurement index and the second measurement index. And a second calculating means for calculating a second optical characteristic of the lens based on the display control means (the display control means includes a result of calculation by the first calculating means or the light receiving element). And when the detection result satisfies the predetermined condition, the second optical characteristic is displayed as the optical characteristic of the lens to be examined and the display means is displayed on the display means as the optical characteristic of the lens to be examined. .

Then, the display control means, when the main surface power calculated by the first calculating means, or the main surface power and the spherical power is less than a predetermined number of degrees, the result of the calculation by the second calculating means as the optical characteristic of the test lens. The lens meter is displayed on the display means.

The display control means is a main surface power calculated by the first calculating means, or when the main surface power and the spherical power are less than a predetermined number of degrees, the optical characteristic and the second calculating means further calculated by the first calculating means. Is a lens meter which compares the optical properties calculated by and displays the calculation results by the second calculating means on the display means as the optical properties of the test lens when both are within a predetermined tolerance.

The display control means compares the optical characteristic calculated by the first calculating means with the optical characteristic calculated by the second calculating means, and when both are within a predetermined tolerance, the calculation result by the second calculating means. Is a lens meter which displays on the display means as an optical characteristic of the lens under test.

The display control means determines whether or not the number of measurement indices of the first region normally detected by the light receiving element satisfies a predetermined ratio or a predetermined number, so that the number of measurement indices does not satisfy a certain ratio or a predetermined number. If not, the lens meter causes the display means to display the calculation result by the second calculation means as the optical characteristic of the lens to be examined.

The indicator plate has a third measurement indicator having a shape distinct from other measurement indicators, and the third measurement indicator comprises a fourth measurement indicator on the measurement optical axis and a fifth measurement indicator at an equidistant distance from the fourth measurement indicator. to be.

The indicator plate has a third measurement indicator having a shape that is distinguished from other measurement indicators, and the third measurement indicator is a lens meter that is combined with the indicator of the first measurement indicator.

Embodiment of this invention is described based on drawing. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the external appearance of the lens meter of embodiment.

1 is a lens meter main body. In the display 2 composed of an LCD or the like, information necessary for measuring a measurement result or an alignment target is displayed. In the switch 3 for input, the thing corresponding to the switch indication displayed on the display 2 is pressed, and the required input instruction | indication, such as switching of a measurement mode, is performed. The test lens LE is placed on the nose piece 4, which is a starting point at the time of measurement. By lowering the lens holder 5, the test lens LE mounted on the nose piece 4 can be stably held.

The lens stand 6, which is movable in the front-rear direction, makes contact with the lower part of the frame (the lower part in the wearing state of the glasses) and stabilizes the measurement of the lens that enters the spectacle frame, thereby making a reference for the Axis (major axis angle) measurement. . The pulling point mechanism 7 is used when giving a point to the lens LE. The READ switch 8 is used when reading the optical characteristic data of the test lens LE. By pressing the READ switch 8, the measured value is held in the display 2 and stored inside the apparatus.

2 is a diagram illustrating an optical system and a control system. L1 is the measurement optical axis of the measurement optical system 20. The measuring optical system 20 includes a measuring light source 21 such as an LED disposed on the optical axis L1, a collimating lens 22, a grid plate 23 on which a measuring indicator is formed, and a two-dimensional image sensor as a light receiving element ( 24). The optical axis L1 passes through the center of the opening 4a of the nose piece 4 and is disposed perpendicularly to the opening plane of the opening 4a. The grid plate 23 is disposed in the vicinity of the nose piece opening 4a. The interval between the image sensor 24 and the upper end of the nose piece 4 (back end of the lens LE) is designed to be smaller than the minimum focal length within the measurement range of the lens LE.

In addition, arrangement | positioning of the grid board 23 may be made into the light source 21 side rather than the to-be-tested lens LE mounted in the nose piece 4. Moreover, you may arrange | position a light source 21 two-dimensionally and comprise the measurement index so that the same measurement light beam as the grid plate 23 may be obtained.

The index pattern of the measurement indicator which the grid plate 23 has is shown in FIG. In this example, circular holes 25 (dot indices) as a plurality of geometrically arranged indices are arranged in a lattice form at intervals of 0.5 mm. Although the holes 25 are arrays of 9x9, you may arrange | position more holes 25 in the range which a measurement light passes through the opening of the nose piece 4 with. In this example, the distance between the centers of the holes 25 is equally 0.5 mm apart, but is not limited thereto as long as it is a predetermined geometric arrangement. Of the holes 25, holes H5 on the optical axis L1 and holes H1, H2, H3, H4 located at square corners having a length of 2 mm around the hole H5. ) Is formed to a diameter of 0.5 mm. Holes 25 other than the holes H1 to H5 are formed to have a diameter of 0.2 mm. The holes H1 to H4 arranged in a constant relationship with the center hole H5 and the hole H5 are distinguished and detected with respect to other holes 25 having different sizes. The center hole H5 is used for detecting the reference position of the deviation of each hole 25 received by the image sensor 24. In addition, when the center hole H5 is not normally detected by the wound or the dirt on the lens LE, the holes H1 to H4 can be replaced. Moreover, the group of the holes H1 to H4 becomes an area which can be measured even when using a small amount of nose piece for contact lenses.

The luminous flux from the light source 21 is made into collimating luminous flux by the collimating lens 22, and is transmitted to the lens LE. Of the transmitted light fluxes, the light flux that has passed through the hole 25 of the grid plate 23 reaches the image sensor 24. The output signal from the image sensor 24 is input to the control unit 40. The control unit 40 is connected to a memory 41 for storing the calculation result and a display circuit 42 for displaying the information such as the calculation result on the display 2.

Moreover, the control part 40 has refractive power with respect to the position of the image (measurement index) of the hole 25 which reached the image sensor 24 through the grid board 23 in the absence of the lens LE. From the positional deviation of the measurement index obtained when the lens LE is placed, the optical characteristics of the lens LE (spherical power S, main power C, principal axis angle A, prism diopter) are determined. Calculate Basically, when the lens LE having only spherical power is placed, with respect to the case where there is no lens LE, each hole image is enlarged or reduced in a circular shape from the optical center of the lens LE. Spherical frequency S is calculated | required based on the deviation of this expansion or reduction. When the lens LE having only the main surface frequency C is placed, each hole image is enlarged or reduced from the center of the main surface axis of the lens LE and shifted. Given this deviation of enlargement or reduction, the frequency C is determined. The principal plane axis angle A is obtained as the central axis of the deviation. In addition, prism frequency is calculated | required by the amount of parallel movement of the hole H5 or the hole in the vicinity. The lens LE having spherical power and principal power may be regarded as a combination thereof (the same method as that used for obtaining the method described in JP-A-60-17335, US3880525, JP-A-50-145249), etc. may be used. Can be).

In the case of using a large number of measurement indices, the same circumference is used using indices such as 5 × 5 (25), 7 × 7 (49), etc., which are located in a diameter of 2-3 mm around the measurement optical axis L1. The optical characteristic of a single focal lens can be obtained with high precision by the operation which averages the optical characteristics of all the sets which are in the set, Preferably four or three adjacent indexes are set into one set. In addition, for the indicators of 5 × 5 (25), 7 × 7 (49), and the like, the least square method is applied based on the detection result of the deviation of each target, The method of calculating an optical characteristic may be sufficient by obtaining the regression plane of S, C, A). By using many more indexes than the conventional calculation of the optical characteristics of only one set by four or three indexes, the optical characteristics of a single focal lens can be obtained with high accuracy.

In addition, when measuring a progressive lens, the optical characteristic is computed in the micro part of a progressive lens by calculating an optical characteristic by making into one pair of four adjacent (at least 3) indexes (holes 25). Lose. That is, distribution of the optical characteristic in the opening of the nose piece 4 is obtained. As a result, in the measurement of the progressive lens, it is possible to efficiently determine whether or not the current measurement position is in the far-end portion, and likewise, it is possible to efficiently determine whether the current measurement position is in the proximity portion.

Here, when measuring the optical characteristic of a short focal lens, the influence of aberration becomes large, so that the hole 25 which is a measurement index | aspect moves away from the measurement optical axis L1. For this reason, the optical of the lens LE is basically carried out using at least three measurement indices arranged in a small region (within a region of 2 to 3 mm in diameter) near the center hole H5 where the measurement optical axis L1 is located. Compute the characteristic (first operation). For example, an optical characteristic is computed based on the detection result of 25 of 5x5 or 49 of 7x7 centered on (H5). However, in the measurement using the indicator near the measurement optical axis L1, when the refractive power of the lens LE is weak, the deviation of the indicator is small, so that each measurement value tends to be unstable, and the reliability of measurement accuracy is inferior. In particular, when the principal surface frequency C is a weak degree, the calculation result of the principal surface axis angle becomes unstable, and the reliability of the measurement accuracy is also deteriorated.

Therefore, in this apparatus, when the principal surface frequency C is below a predetermined number of degrees, the number of the measurement region and the measurement index is enlarged with respect to the small region (in the region of diameter 2 to 3 mm) near the measurement optical axis L1 ( Increase) to calculate the optical characteristic (second operation). When the principal surface frequency C is a weak number, even if the range of the measurement region from the measurement optical axis L1 is widened, the effect of aberrations is small. Therefore, the measurement accuracy of the principal surface axis angle is increased as the number of measurement indexes increases. Stability is attained. Hereinafter, the operation example is demonstrated based on the flowchart of FIG.

The measurement mode of the device includes a mode for measuring a short focal lens and a mode for measuring a progressive lens, where the measurement mode of the short focal lens is selected. The examiner selects the left and right sides of the lens to be measured by pressing a switch for specifying left and right selection of the lens displayed on the display 2.

When the lens LE is mounted on the nose piece 4, the controller 40 is centered on the optical axis L1 among a plurality of index images (images of the holes 25) detected by the image sensor 24. Each measured value (S, C, A, prism frequency) is calculated on the basis of the deviation of the index image of 7 x 7 (49 pieces) arranged in (S-1). 5A is an example of the screen of alignment displayed on the display 2 at this time. Reference numeral 50 denotes a reticle for alignment, and measurement value display sections 51 and 52 display measurement values for each of the left and right. And the indication of the mark 53 shows that the right lens is currently measured. Each measured value obtained at this time is displayed on the right measured value display part 51. Moreover, the ring target 54 is displayed on the display 2 based on the deviation direction of the optical center with respect to the optical axis L1 of the lens LE, and the prism frequency which is the amount of offset. The display position of the ring target 54 may be obtained based on the detection results of the holes H1 to H5 to align.

When the lens LE is moved so that the prism power Δ falls below 0.5Δ, the ring target 54 is switched to the cross-lined target 55 (see Fig. 5B). If only the frequency is measured, the measured value is held by pressing the READ switch 8 in this state. In the case where the lens LE is in-pointed, for a more accurate alignment, the lens LE is moved so that the cross target 55 is directed toward the center of the reticle 50, and when the prism degree is less than 0.1Δ, The cross target 55 is converted to the cross target 57. This allows the inspector to know that the precise alignment has been completed.

In the measurement of such a short focal lens, the calculation of the optical characteristics by the control unit 40 is continuously performed at regular time intervals. At this time, the control unit 40 has a predetermined principal power δcD (and spherical power) among the optical properties obtained based on the deviation of the 7 × 7 (49) indicator images arranged around the optical axis L1. Is εsD, D: diopter) or less (S-2). For example, delta cD assumes a negative reading of the principal surface power, and makes a weak number less than -0.5D.

When the principal power is less than or equal to δ cD (and the spherical power is εsD), even if the measurement area and the number of indices are enlarged, the influence of the aberration is small. The optical characteristic is computed by enlarging the number of the measurement area | region of 7x7 (49 pieces) and indicators which are phosphorus. The control part 40 increases the number of measurement indices by enlarging a measurement area | region further from the calculation of the optical characteristic by the 7x7 hole 25, and it is 9x centering on the center hole H5. The optical characteristic based on nine (81) index images is calculated (S-3).

Here, preferably, the following determination conditions are further formed (in addition, the following determination conditions may be defined as a single condition). The control part 40 compares each measured value computed by 7x7, and the measured value computed by 9x9. As a result of comparing the respective measured values, it is judged whether or not each falls within the tolerance range (S-4). In the present embodiment, when the difference between the spherical power and the main power is both within the tolerance ± 0.06D, the influence of the aberration due to the enlargement of the number of the measurement area and the measurement index is small, and it is more reliable to calculate from 9 × 9 index images. As this high measured value is obtained, the control part 40 displays the measurement result based on 9x9 indicator image on the display 2 (S-5). When the READ switch 8 is pressed, the control unit 40 holds the measured value and stores it in the memory 41 (S-6).

On the other hand, as a result of comparing the measured values by 7x7 and 9x9 in step (S-4), when the difference between the spherical power and the main power is out of the tolerance range, the improvement of the stability of the measured value is improved. Unexpectedly, the control part 40 sets the calculation result by 7x7 index image as a measured value (S-7).

In the previous step (S-2), when the principal surface power is stronger than the predetermined weakness number δcD, the influence of aberration becomes stronger when including 9 x 9 index images arranged around the optical axis L1, and 7 x Since the reliability of accuracy can be ensured even in the measurement results by the seven indicator images, the calculation results by the seven by seven indicator images are displayed as the measurement results (S-7).

In addition, in the determination of step (S-4) described above, the results of performing 7x7 operations and 9x9 operations multiple times (for example, three times) may be changed based on the result. do. If the difference between the two times is within the tolerance ± 0.06D and the deviation of each measured value measured three times in succession is also ± 0.06D, then the stabilization of the measured value and the precision of the principal axis angle are expected. Switch to the measurement result calculated by × 9. If the above conditions deviate, the process of making 7 x 7 calculation results as measurement results per se is continued. This is continued until the lens is moved greatly (as can be seen from the change in the prism frequency) or until a new lens is placed on the nose piece 4, but even if there is no lens movement, it can be checked again every few seconds and determined. do.

In addition, embodiment of this invention is not limited to the above. You may change suitably the principal surface frequency used for determination of step (S-2), and the criteria used for determination of step (S-4). Moreover, although the method of switching between 7x7 and 9x9 centering on the optical axis L1 demonstrated the number of the index image made into the measurement object, it is not limited to these numbers. For example, 5 × 5 indexes centered on the hole H5 located in the measurement optical axis L1 are taken as the normal measurement targets, and the number of measurement indexes is increased by enlarging an area therefrom when the principal plane is δcD or less. Switch to increase In addition, an index on the same circumference with a diameter of 2 mm centered on the measuring optical axis L1 may be converted to an index located inside the enlarged diameter in the case where the main surface power is δcD or less as a normal measurement target. . Moreover, 5 x 5 pieces, 7 x 7 pieces, and 9 x 9 pieces may be switched in multiple stages depending on the principal surface frequency.

In the above, the calculation (second operation) of enlarging the number of measurement areas and measurement indices according to the frequency of the lens LE is assumed to be used. Applying is effective. That is, in the index image of the small area (7x7) near the measurement optical axis L1 where there is a wound or contamination on the lens LE, the index image of the index image detected normally by the lack of light quantity or the shape defect of the index image is If the number is not satisfied with a predetermined number or a predetermined ratio (40%, 50%, etc.), the measurement result tends to be disturbed, and the reliability of the measurement accuracy also becomes insufficient. In this case, the control part 40 displays on the display 2 the measurement result obtained by the 2nd operation based on 9x9 indexes. In this case, the index image detected normally increases, and the stability of a measurement result is improved. In addition, improvement in measurement accuracy can also be expected. When the number of normally detected index images satisfies a predetermined number or a predetermined ratio, the control unit 40 itself displays the measurement result obtained by the calculation of the 7x7 index images on the display 2.

In the calculation of each measured value, it is also possible to select only an index provided with the value by obtaining the standard deviation of each measured value. Compared with the detection processing of the index image, the calculation of the optical characteristic can be performed in a short time, so after the detection of one measurement index, the index of the adoption / non-employment is selected and improved to the level that the standard deviation requires. Repeat this until Thereby, a stable measurement result is obtained without prolonging a measurement time.

In addition, switching from the measurement result by the said 7x7 indicator to the measurement result by the 9x9 indicator may not necessarily be suitable for use by a lens maker etc. For this reason, it is preferable to make it selectable by the selection switch provided in the display 2, whether to apply this switching function or to leave it as the measurement result by the 7x7 index | item as before.

In the second calculation of the above embodiment, the optical properties are calculated by enlarging (increasing) the number of the measurement region and the measurement index together, but any one of them may be used. For example, in a typical first operation, 49 of 7 × 7 in the small area near the measurement optical axis L1 are targeted. In the second operation, the calculation time is expanded to 9 × 9 measurement areas. In order not to lengthen, it computes for 49 measurement indices similar to 1st calculation, for example, not making it all 9x9 enlarged, and making it one space | interval. In addition, as an example of expanding only the number of measurement indices, in order to shorten the calculation processing time, in the conventional first operation, twenty-five measurement indices spaced at one interval are calculated from among 7 x 7 measurement regions. On the other hand, in the second calculation, the calculation is performed on all measurement indices in the 7 × 7 measurement areas. Although it is preferable to expand the number of a measurement area | region and a measurement index | membrane together like the previous embodiment, the 2nd calculation produces a stable result with respect to the conventional 1st calculation only by one side.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the external appearance of the lens meter of embodiment.

It is a figure explaining the optical system and control system of embodiment.

It is a figure explaining the index pattern of a measurement indicator.

4 is a view for explaining an example of the operation of the embodiment.

5A to 5C are views for explaining the display screen of the alignment.

Claims (7)

The lens meter which measures the optical characteristic of the lens to be examined, Measurement optical system (The measurement optical system includes a plurality of measurement indexes arranged in a predetermined pattern around the measurement optical axis. (The measurement index includes a first measurement index in a first area close to the measurement optical axis and a second outside of the first area. And a light receiving element for receiving the measurement light beam passing through the lens to be examined), Arithmetic means for calculating an optical characteristic (the arithmetic means includes first arithmetic means for calculating a first optical characteristic of a lens based on a detection result of a first measurement index by the light receiving element, a first measurement index and a second measurement And second calculating means for calculating a second optical characteristic of the lens based on the detection result of the index); Display control means (The display control means uses the second optical characteristic as the optical characteristic of the test lens when the calculation result by the first calculating means or the detection result by the light receiving element satisfies the predetermined condition. When not satisfied, the first optical characteristic is displayed on the display means as the optical characteristic of the lens to be examined). The method of claim 1, The display control means displays the calculation result by the second calculation means as an optical characteristic of the test lens when the principal surface power, or the principal surface power and the spherical power calculated by the first calculation means are equal to or less than a predetermined degree. Lens meter to display on the means. The method of claim 2, The display control means is a main surface power calculated by the first calculating means, or when the main surface power and the spherical power are less than a predetermined number of degrees, the optical characteristic and the second calculating means further calculated by the first calculating means. And comparing the optical characteristics calculated by the display to display the calculation result by the second calculating means on the display means as the optical characteristics of the test lens when both are within a predetermined tolerance. The method of claim 1, The display control means compares the optical characteristic calculated by the first calculating means with the optical characteristic calculated by the second calculating means, and when both are within a predetermined tolerance, the calculation result by the second calculating means. The lens meter which displays on the display means as an optical characteristic of a test lens. The method of claim 1, The display control means determines whether or not the number of measurement indices of the first region normally detected by the light receiving element satisfies a predetermined ratio or a predetermined number, so that the number of measurement indices does not satisfy a certain ratio or a predetermined number. If not, the lens meter causing the display means to display the calculation result by the second calculation means as the optical characteristic of the lens to be examined. The method of claim 1, The indicator plate has a third measurement indicator having a shape distinct from other measurement indicators, and the third measurement indicator comprises a fourth measurement indicator on the measurement optical axis and a fifth measurement indicator equidistant from the fourth measurement indicator. The method of claim 1, The indicator plate has a third measurement indicator having a shape distinct from other measurement indicators, and the third measurement indicator is combined with the indicator of the first measurement indicator.

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