JP3069311B2 - Automatic lens meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic lens meter, and more particularly, to a mechanism for displaying an alignment target indicating a relative position of a test lens with respect to an optical axis of a measuring optical system.

[0002]

2. Description of the Related Art Various measuring devices have been proposed for lens meters for automatically measuring various optical characteristics of spectacle lenses.

In these automatic lens meters, a mechanism for indicating the relative position of the center of the optical axis of the lens to be measured with respect to the optical axis of the measuring optical system is indispensable. Is displayed on the display together with the mark indicating the measurement optical axis.

Conventionally, there are the following methods for displaying the relative positional relationship between the optical axis of the test lens and the optical axis of the measuring optical system.

[0005] As a first display method, the amount of prism (frequency) generated when the optical axis of the measuring optical system is shifted from the optical axis center of the lens to be measured is measured, and the position of the target is determined based on the magnitude of the prism power. Is displayed. The optical aberration has a correlation with the refractive power of the lens.However, the amount of deviation from the optical axis of the measuring optical system and the center of the optical axis of the lens to be measured is indicated by the amount of prism, thereby defining the guaranteed range of the measurement accuracy of the optical characteristics. There is an advantage that it can be set on a uniform basis.

In the second method, an eccentric amount (distance) between the optical center of the lens and the optical axis of the measuring optical system is calculated, and the position of the target is displayed according to the eccentric amount. According to this method, there is an advantage that the movement of the test lens and the movement of the target can be made proportional.

[0007]

However, in the case of the display system based on the first prism power, there is a problem that a lens having a large power has a large change in the prism value even near the optical center, so that alignment is difficult.

There is also a problem in manufacturing cost that the positioning accuracy cannot be improved unless the resolution of the display is high.

On the other hand, in the case of displaying the position of the target at a position proportional to the amount of eccentricity between the optical center of the second lens and the optical axis of the measurement system, the range in which the measurement accuracy is guaranteed is uniform. If set, a lens having a large refractive power must be used as a reference. Therefore, there is a problem that strict alignment is required even for a lens having a small refractive power.

In order to achieve high-accuracy alignment, there is no choice but to increase the resolution of the display or to increase the magnification. However, the former has a problem of manufacturing cost and the latter has a problem of reducing the display area. .

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide an automatic lens meter that can quickly measure optical characteristics and perform high-precision alignment with a lens of any power.

[0012]

Means for Solving the Problems The present invention is characterized by having the following configuration in order to solve the above-mentioned problems .
You. (1) An automatic lens meter that automatically measures optical characteristics such as spherical power and astigmatic power of a test lens placed in a measurement optical system, based on the measurement results in the measurement optical system.
And alignment detection means for detecting a positional deviation of the lens with respect to the optical axis of the measuring optical system have, for alignment
A display for displaying a reticle, and an alignment target formed on the display for alignment detection.
The position of the alignment target is moved and the alignment target is moved in accordance with the alignment state based on the detection result of the output unit.
And display control means for changing the shape of the image . (2) In the automatic lens meter of (1),
Kuru has secured the precision required for axial alignment of spectacle lenses
The first circle indicating the area and the accuracy of the measurement of the optical characteristics are confirmed.
And a second circle indicating the preserved area.
Sign. (3) The automatic lens meter of (1), wherein
Kuru has secured the precision required for axial alignment of spectacle lenses
The first circle indicating the area and the accuracy of the measurement of the optical characteristics are confirmed.
A second circle indicating the maintained area.
When the means moves from the second circle to the first circle
Specially, it changes the shape of the alignment target.
Sign. (4) Sphericity of the test lens placed in the measuring optical system
Automatic lens that automatically measures optical characteristics such as number and astigmatism
In the distance meter, based on the measurement result in the measurement optical system,
The displacement of the test lens with respect to the optical axis of the measuring optical system.
Alignment detection means to detect and alignment
A display for displaying the reticle, and
Form an alignment target on the
When the alignment is completed based on the detection result of the
Display control to change the shape of the alignment target
Means. (5) In the automatic lens meter of (4), the display is
When the alignment is completed, the control means
That target of 90 degrees or 180 degrees direction of the line is Shin building
It is characterized by. (6) In the automatic lens meter of (4), the display is
The control means that the direction of astigmatism axis coincides with the direction of 90 degrees or 180 degrees
90 degrees or 180 degrees of the cross line target
It is characterized in that the line in the degree direction extends.

[0013]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of an automatic lens meter according to an embodiment of the present invention.

Reference numeral 1 denotes a display, which is a reticle and an alignment target 2 which are shown around the optical axis of the measuring optical system.
(FIG. 1 shows a corona target, which will be described in detail later).
It is composed of an LED dot matrix display for displaying measurement results and the like. Reference numeral 3 denotes a print switch for printing a measurement result, 4 denotes an addition measurement switch for switching to an addition measurement mode, 5 denotes a left / right selection switch, and 6 denotes a measurement value reading switch.

Reference numeral 7 denotes a lens holder, 8 denotes a nosepiece, and a test lens to be measured is placed on the nosepiece 8,
The lens holder 6 is lowered to hold the test lens.

Next, an embodiment of the measuring optical system of the automatic lens meter will be described.

FIG. 2 is an optical system layout diagram of the automatic lens meter.

Reference numeral 11 denotes a light emitting diode such as an LED, and four light emitting diodes are arranged near the focal point of the objective lens 12 orthogonally to the optical axis. When the test lens 15 is set on the nosepiece 8, the LE
The D driver operates to sequentially turn on the four LEDs a, b, c, and d.

Reference numeral 13 denotes a measuring target plate having orthogonal slits, which is fixed or movable near the focal points of the objective lens 12 and the collimating lens 14.

The nosepiece 8 is arranged near the focal points of the collimating lens 14 and the imaging lens 16.
Reference numeral 17 denotes a half prism, and reference numeral 18 denotes an image sensor provided orthogonal to the optical axis.

The light from the LED is imaged by the objective lens 12 on two orthogonal image sensors 18 via the collimating lens 14, the test lens 15, and the imaging lens 16.

As shown in FIG. 3, signals from the two image sensors 18 are input to a comparator 22 and a peak hold circuit 23 via a CCD drive circuit 21. The peak voltage input to and detected by the peak hold circuit 23 is converted into a digital signal by the A / D converter 24 and then input to the computer 25. The digital signal of the peak voltage output from the peak hold circuit 23 is converted into a voltage signal of の of the peak voltage by the D / A converter 26 via the computer 25,
2 is input. This signal is compared with the signal directly input to the comparator 22 to generate a strobe signal. The strobe signal causes the signal of the counter 27 to enter the latch 28,
The position of the light-dark edge is read from the waveform at that time, and the computer 25 detects the coordinate position.

Next, a method of calculating a measured value from the detected coordinate position will be briefly described.

The target 13 is individually illuminated by four LEDs. However, when there is no lens to be inspected and when the lens of 0D is placed on the nosepiece 8, the LED is
Target images cut on the image sensor 18 by a, b, c, and d all overlap.

When the test lens 15 has only the spherical refractive power, the position of the target to be imaged on the image sensor 18 moves on the image sensor 18 by an amount corresponding to the spherical refractive power.

When the test lens 15 has only a cylindrical refractive power, a light beam incident on the cylindrical lens has a refractive power in a direction (or the same direction) orthogonal to the main diameter line. The columnar refractive power can be calculated from the movement amount of the target image.

When the test lens 15 has both a spherical refractive power and a cylindrical refractive power, the target image moves on the image sensor 18 by an amount corresponding to each refractive power value and forms an image.

Now, when the LEDs a, b, c, and d are turned on, the centers of the target images are A (x _a , y _a ),
_{B (x b, y b)} , C (x c, y c), D (x d,
y _d )

[0030]

(Equation 1) After all,

[0031]

(Equation 2) Becomes

The coordinate position is detected by the computer 25, the spherical refraction, the column refraction, the axis angle, and the amount of prism are calculated based on the above-mentioned formula, and the values are digitally displayed.

When the lens to be inspected has a power (refracting power) other than 0D, the four target images are shifted in image position by an amount proportional to the power due to blurring, which causes a measurement error. Therefore, in an actual apparatus, it is desirable to move the measuring target so as to reduce the amount of displacement due to blurring, and to calculate the optical characteristics of the lens to be measured from the moving amount of the measuring target and the image position.

Next, a method of forming an alignment target will be described with reference to the flowchart of FIG.

When the apparatus is in the measurement mode, the measurement system operates continuously at regular intervals, and the optical characteristics of the lens to be measured are measured. As described above, the computer 25 calculates the spherical refractive index, the columnar refractive index, the axial angle, and the prism amount of the test lens at that position. Spherical refraction, cylindrical refraction,
Along with displaying the axis angle at the bottom on the display 1,
According to the measured amount of prism, a corona target is displayed by a display control circuit at a predetermined position of the reticle centered on the optical axis of the measurement optical system displayed on the display.

FIG. 4 is an enlarged view of the reticle display section of the display. A 16 × 16 dot matrix display is arranged at the center, and an LED array composed of eight LEDs is radially arranged outside the matrix display. As a reticle centered on the optical axis of the measuring optical system, circles of 1 °, 1.5 ° and 2 ° centered on the optical axis are indicated on the display.

In this embodiment, when the measuring prism is at least 0.25 °, corona target display is performed. When the angle is not less than 0.25 ° and not more than 2 °, the corona target is moved right and left or up and down every 0.25 ° in proportion to the prism value. 2 △
When the distance exceeds 1, the LED array is moved outward on the nearest LED array every 1 °.

1 indicates that if a corona target is included in the circle, measurement can be performed without being affected by aberrations or the like (see FIG. 4). Therefore, alignment for measuring optical characteristics can be performed quickly.

Further, when it is necessary to perform the axial striking of the spectacle lens, the alignment is performed to less than 0.25 °. 0.2
If the alignment is less than 5 °, the target switches to a crossline target (see FIG. 5). At this time, the movement of the target is not a movement proportional to the prism amount, but a movement proportional to the distance (eccentric amount) between the optical center of the lens to be measured and the measurement optical axis. The amount of eccentricity is obtained from the power of the lens to be measured and the prism value by the following equation.

Amount of eccentricity (mm) = prism / frequency × 10 In this embodiment, in accordance with a generally required standard, when the target is located at the center, alignment is made to be 0.2 mm or less. If there is an eccentric amount exceeding 0.2 mm, the target is shifted from the center by one dot every 0.4 mm eccentricity. For example, S is + 20D
When the lens is aligned at 0.25 ° or less, the amount of eccentricity becomes 0.2 mm or less, so that the cross line target is displayed at the center (see FIG. 6). By switching the alignment method in two stages, high-precision alignment can be performed very easily.

In the case of an astigmatic lens, the astigmatic axis angle is 1
Axle to 80 degrees (or 90 degrees) or prescription value. When aligning to the prescription value, determine the axialness by looking at the display on the display. When aligning with 180 degrees, the horizontal line of the target is extended, and when matching 90 degrees, the vertical line of the target is extended, and alignment is completed. (See FIG. 7). This is done by inputting the shaft angle to the traverse device like a recent so-called patternless traverse device, and the axial strike angle is uniformly 18
This is because the number of devices that can be set to the direction of 0 degrees or 90 degrees has increased.

The scale of the reticle is not limited to the above case, but may be variously changed depending on the required accuracy.

[0043]

According to the automatic lens meter of the present invention,
High-precision alignment can be performed very easily, and it can be realized by simple operations, particularly when relatively coarse alignment required for measurement and high-precision alignment is required, such as during axial driving.

[Brief description of the drawings]

FIG. 1 is a front view of an automatic lens meter according to the present embodiment.

FIG. 2 is an optical system layout diagram of the automatic lens meter according to the present embodiment.

FIG. 3 is a block diagram illustrating a control system of the automatic lens meter according to the present embodiment.

FIG. 4 is a display display of a corona target.

FIG. 5 is a display display of a cross line target.

FIG. 6 is a display display showing a state where alignment has been completed by a cross line target.

FIG. 7 is a display showing a state where alignment of the astigmatic lens is completed.

FIG. 8 is a flowchart illustrating an alignment display method according to the present embodiment.

[Explanation of symbols]

 Reference Signs List 1 display 2 alignment target 3 print switch 4 addition measurement switch 5 left / right selection switch 6 reading switch 7 lens holder 8 nosepiece

Continuation of the front page (56) References JP-A-63-131042 (JP, A) JP-A-62-2200238 (JP, A) JP-A-1-135344 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) G01M 11 / 00- 11/02 Practical file (PATOLIS) Patent file (PATOLIS)

Claims (6)

(57) [Claims] 1. An automatic lens meter for automatically measuring optical characteristics such as a spherical power and an astigmatic power of a test lens placed in a measuring optical system , wherein the measurement result in the measuring optical system is
And alignment detection means for detecting a Re <br/> not a position of the lens with respect to the optical axis of the measuring optical system based and positioning
A display for displaying a reticle , and an alignment target formed on the display. The position of the alignment target is moved in accordance with the alignment state based on the detection result of the alignment detecting means.
And a display control means for changing the shape of the automatic lens meter. 2. The automatic lens meter according to claim 1, wherein
The reticle ensures the accuracy required for axially striking the spectacle lens.
A first circle indicating the preserved area, and
A second circle indicating an area where the accuracy is secured.
An automatic lens meter. 3. The automatic lens meter according to claim 1, wherein
The reticle ensures the accuracy required for axially striking the spectacle lens.
A first circle indicating the preserved area, and
A second circle indicating an area where the accuracy is secured.
The display control means moves from the second circle to the first circle.
Changes the shape of the alignment target
An automatic lens meter. 4. A sphere of a test lens placed in a measuring optical system.
Automatic measurement of optical characteristics such as surface power and astigmatism power
In the lens meter, the measurement result in the measurement optical system
The position of the test lens with respect to the optical axis of the measuring optical system
Alignment detection means for detecting
A display for displaying a reticle, and the display
Form an alignment target on
Alignment is completed based on the detection result of the
And display for changing the shape of the alignment target
An automatic lens maker, comprising:
Ta. 5. The automatic lens meter according to claim 4, wherein
When the alignment is completed, the display control means
The 90 ° or 180 ° line of the in-target extends.
Automatic lens meter 6. The automatic lens meter according to claim 4, wherein
The display control means has an astigmatic axis direction of 90 degrees or 180 degrees.
When the direction matches, the crossline target 90 degrees or
Is characterized by the fact that a line extending in the direction of 180 degrees extends.
Lens meter.