JPH06194266A - Lens meter - Google Patents

Abstract

PURPOSE:To permit a measuring operator to discriminate a measuring indicator projected on a photodetector means by providing a discrimination means for discriminating the measuring indicator. CONSTITUTION:A luminous flux emitted from a light source 1 is converted to a parallel luminous flux by a collimator lens 2 so that the parallel luminous flux is projected to a lens to be inspected L located on a lens supporting stand 3. The luminous flux is refracted in accordance with the refraction characteristic of the lens L to pass therethrough to be projected on a mask plate 4 via an opening 3a of the lens supporting stand 3. A part of the projected luminous flux is selectively transmitted through the mask plate 4 corresponding to a shape of a mask pattern, i.e., measuring indicator, of the mask plate 4 to be projected on a photodetector 5 consisting of an area CCD. Image information of projection pattern which is obtained from the photodetector 5 by being scanned by means of a control operating circuit 6 is stored in a RAM 9. If necessary, the image of the projection pattern is indicated on an indication device 8, i.e., discrimination means, via the circuit 6 so that a measuring operator can realize the projection condition of the projection pattern on the photodetector 5 from the shape and the position of the indicated image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens meter used for measuring optical characteristics of spectacle lenses, such as spherical power, cylindrical axis angle and the like.

[0002]

2. Description of the Related Art As one conventional example of an automatic lens meter, there is an apparatus disclosed in Japanese Patent Application Laid-Open No. 57-29923 filed by the applicant of the present application. In this conventional example, a light from a light source is projected by a collimator lens as a parallel projection light beam toward a lens to be inspected, and a light beam refracted and transmitted by the lens to be inspected is selectively transmitted by a mask pattern having a predetermined shape, and a two-dimensional area is formed. The image is projected onto an optical inspection means composed of a CCD, and the refraction characteristics of the lens to be inspected are measured from the shape or position change of the projection pattern and the mask pattern. As the mask pattern, an annular type, a crossed two straight line type, a three straight line and three crossed type are used.

[0003]

In the conventional apparatus, since the diameter of the parallel light beam projected on the lens to be inspected and the mask pattern are large, a small lens of a multifocal lens, a near designation portion or a soft contact of a progressive multipoint lens. It was difficult to measure an inspected lens such as a lens or a progressive contact lens having a narrow region to be measured with a uniform refraction characteristic value.

In order to solve this problem, there is provided a lens meter having a target projecting means for selectively projecting a plurality of types of measuring targets onto the light detecting means, the measuring area of a lens under test being measured. A lens meter provided with index selecting means for selecting one of the plurality of measurement targets according to the size is considered.

In such a lens meter, the type of the measurement target projected on the light detecting means is "a small lens of a multifocal lens, a near designation portion of a progressive multi-point lens, a soft contact lens or a progressive lens. It is possible to more easily carry out the measurement work by knowing whether the target is a visual target such as a contact lens or a standard visual target for a subject lens. Therefore, it is desirable for the measurer to know the type of measurement target projected on the light detection means.

Therefore, the present invention meets such a demand, and an object of the present invention is to provide a lens meter which enables a measuring person to identify a measurement target projected on a light detecting means.

[0007]

In order to achieve this object, the present invention is a lens meter having a target projection means for projecting a measurement target onto the light detection means. The lens meter is provided with an identifying means for identifying the measured visual target.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

[First Embodiment] FIGS. 1 to 5 show a first embodiment of the present invention.
In the embodiment, reference numeral 1 is a light source composed of a light emitting diode. A light beam emitted from the light source 1 is collimated by a collimator lens 2 and projected onto a lens L to be inspected mounted on a lens holder 3. It

The projected parallel light beam is refracted and transmitted according to the refraction characteristics of the lens L to be inspected, and the transmitted light beam is projected onto the mask plate 4 through the opening 3a of the lens holder 3.
Then, a part of the projected luminous flux is selectively transmitted according to the shape of the mask pattern (measurement target) of the mask plate 4, and is projected onto the detection element 5 composed of an area CCD. The area CCD 5 is arranged inside the focus F of the lens L to be inspected (on the side of the lens holder 3). The light source 1, the collimator lens 2, and the mask plate 4 constitute a target projection unit A that projects the measurement target onto the detection element 5.

The control arithmetic circuit 6 mainly composed of a microprocessor scans the area CCD, detects the change in the shape of the projection pattern, and based on this, obtains the refraction characteristics of the lens L to be inspected and displays it on the display unit 8. To do. Further, a storage device 9 composed of, for example, a RAM is connected to the control arithmetic circuit 6, and image information of a projection pattern from the photodetector 5 scanned by the control arithmetic circuit 6 is stored in the storage device 9. .

By displaying the image of the projection pattern on the display 8 (identifying means) via the control arithmetic circuit 6 as needed, the measurer can display on the photodetector 7 according to the shape and position of this display image. Since the projection state of the projected pattern on the lens can be known, the reliability of measurement can be improved and the alignment of the lens L to be tested can be facilitated. In particular, when the lens L to be inspected is a soft contact lens, its shape is likely to be deformed during measurement, but by knowing the display image of the projection pattern as described above, the presence or absence of deformation can be known in advance.

In this embodiment, the photodetector 7 detects the transmitted light from the mask pattern in a non-imaging state.
The projection pattern becomes a blurred image on the photodetector 7.
However, as will be described later, the center line of the pattern is calculated by the control arithmetic circuit 6 and the data is stored in the storage device 9, so that the display image of the projected pattern on the display 8 is the center of the pattern. A line-based image is obtained.

FIG. 2A shows the structure of the mask plate 4 described above. The mask plate 4 is composed of liquid crystal elements. The mask plate 42 has a thick straight line portion A of length X and a thin straight line B of length X.
Has a pattern electrode 41 configured to intersect at an angle θ at an intersection point C, and a pattern electrode 42 having a similar shape but smaller in size than the pattern electrode 41 on the front surface. The pattern electrode 41 is electrically connected to the a-side contact of the switch 71 which is the switching means, while the pattern electrode 42 is electrically connected to the b-side contact of the switch 71. A common electrode 43 is provided on the back surface of the mask plate 4 made of a liquid crystal element, and the common electrode 43 is connected to the (+) side of the DC power source 72 of the drive circuit 7. The (−) side of the power source 72 is connected to the movable contact piece d of the switch 71. The switching of the switch 71 is performed by the control signal s from the control arithmetic circuit 6. Further, on the back surface of the mask plate 4, a light-shielding plate 44 having an opening of the same shape as the pattern electrodes 41, 42 is provided so as to shield light except for the portions of the pattern electrodes 41, 42 as shown by the shaded areas in the figure. There is. In this way, the pattern electrodes 41 and 42 drive the mask pattern P ₁ or P ₂ (measurement target) to selectively transmit the light from the lens L to be inspected.

Now, as shown in FIG. 2 (A), a
When the side points are closed, only the mask pattern P ₁ transmits the light flux from the lens L to be tested and projects the transmitted light flux onto the area CCD 5. The area CCD 5 detects the projection pattern P ′ ₁ as shown in FIG.
The refraction characteristics of the lens L to be measured are calculated from the lengths X ′, X ′ and θ ′ of the straight lines A ′, B ′ of ‘ ₁ ’ and found. The calculation method is described in detail in the above-mentioned JP-A-57-29923, so please refer to it.

If the switch 71 is switched to the b-side contact, the light passing through the lens under test can be selectively transmitted only from the mask pattern P2.
The same measurement can be performed when the refraction characteristics of the narrow measured region are the master pattern P ₁ .

FIG. 3 shows another example of the mask pattern (measurement target) formed on the mask plate 4. The mask pattern P ₁ (measurement target) is a straight line portion 101 of one line and a straight line of two lines. The part 102 and the straight line part 103 of the three main lines have three intersections 104, 105,
Configured to have 106. Mask pattern P
₂ (measurement target) has the same structure as the mask pattern P ₁ and has a similar shape, and the size thereof is reduced as in the case of FIG. 2 (A). According to the configuration of FIG. 3, if at least two points can be detected for one straight line projection pattern by scanning the area CCD 5 with the projection pattern P ₁ ′, that is, for the straight line portion 101, the points 101a and 101b and the straight line portion 10 can be detected.
2, points 102a and 102b, and straight line portion 103, points 103a and 102b.
If 103b can be detected, the straight line equation of the projection pattern of each straight line 101, 102, 103 can be determined, and the intersection point position of the projection pattern P ₁ ′ can be determined from these three straight line equations.
The length and crossing angle of each of the projected patterns 1 and 102 can be known.

FIG. 4 shows the mask pattern P ₁ of the mask plate 4,
Another example of P ₂ (measurement target) is a mask pattern P ₁
Is four straight lines 201, 202, 203 and 204 which are four virtual intersections Q,
It is configured to have U, V and W. The master pattern P ₂ has the same structure as P ₁ and has a similar shape, and its size is small. In this example, as in the example of FIG. 3, by knowing the coordinates of at least two points on each projection line of the projection pattern,
Knowing the linear equation of each projected line, the intersection U of the projected patterns
The coordinates of ', V', W ', and Q'can be known.

Virtual intersection points Q, U, V, W of the mask pattern
From the virtual crossing Q ', U', V ', W'of the projection pattern to obtain the refraction characteristics of the lens to be inspected. The method for obtaining the refractive property is described in Japanese Patent Application Laid-Open No. 57-19
Please refer to it because it is described in detail in the 9933 publication.

FIG. 5 shows still another structure of the mask pattern (measurement target) of the mask plate 4, which is a mask pattern P ₁
(Measurement target) has a large annular shape and mask pattern P
₂ (Measurement target) is a small circular ring concentric with P ₁ . The light from the lens to be inspected that is selectively transmitted by the annular pattern P ₁ or P ₂ is projected as an ellipse on the area CCD 5 if the lens to be inspected L is astigmatic. If the coordinates of at least five points on this elliptical projection pattern are detected, the lens L
It is possible to obtain the refraction characteristics of. The method for obtaining this is disclosed in the above-mentioned JP-A-57-29923, so please refer to it.

As described above, by configuring the mask plate 4 with a liquid crystal element and specifying the mask pattern by the shape of the pattern electrode, the mask pattern can be selected by electrifying the pattern electrode. In this embodiment, the number of mask patterns is two, but the number is not limited to this, and the number may be increased or decreased to three or four as needed.

[Second Embodiment] FIGS. 6A and 6B show a second embodiment of the present invention. The mask plate 4 is composed of a mask pattern plate 301 and a liquid crystal shutter plate 302. Here is an example. The mask pattern plate 301 is formed by forming the above-described light-transmitting mask patterns P ₁ and P ₂ (measurement targets) on one surface of the glass substrate 303 by vacuum aluminum vapor deposition. The liquid crystal shutter plate 302 is provided on the other surface side of the glass substrate 303, and the mask pattern P is provided on both surfaces of the liquid crystal shutter 302.
A shutter electrode 311 corresponding to ₁ and a shutter electrode 312 corresponding to the mask pattern P ₂ are formed. The shutter electrode 311 is connected to the a-side contact of the switch 71, and the shutter electrode
312 are electrically connected to the b-side contacts of the switch 71, respectively.

With this configuration, by switching the switch 71, the mask patterns P ₁ and P ₂ are selectively selected and the light passing through the lens to be tested is selectively projected onto the area CCD 5.

This embodiment is useful when the mask pattern is complicated as shown in FIG. 3 and it is difficult to form the mask pattern with the pattern electrodes.

[Third Embodiment] FIGS. 7, 8A and 8B show a third embodiment of the present invention.

An auxiliary lens pedestal 240 having a selective light shielding plate 241 is detachably fitted to the lens pedestal 3. A plurality of auxiliary lens pedestals 240 are prepared according to the mask pattern (measurement target) of the mask plate 4. A light-shielding plate 241a of one auxiliary lens pedestal has a light-shielding portion 242 formed on the outside of a glass substrate in an annular shape by aluminum vacuum deposition, as shown by the hatched lines in FIG. 8 (A). This light shield 242 has a large mask pattern
It is formed so as to block the light flux PXa passing through the lens to be examined toward P ₁ (measurement target).

Light-shielding plate for the other auxiliary lens pedestal (not shown)
241b is a circular light-shielding portion 24 formed by vacuum aluminum vapor deposition on the inner surface of the glass substrate, as indicated by the diagonal lines in FIG. 8 (B).
Having 3. This light shielding portion 243 has a small mask pattern P
₂ It is formed so as to block the light PXb passing through the lens to be measured, which goes to ₂ (measurement target).

With this structure, a plurality of auxiliary lens pedestals 40 are selectively inserted into the lens pedestal 3 to provide the mask plate 4
The passing light can be guided from the lens L to be tested to only one of the plurality of mask patterns.

[Fourth Embodiment] FIGS. 9 (A) and 9 (B) show a fourth embodiment of the present invention. As shown in FIG. 9 (A), the light sources have different emission wavelengths. Two light sources 1a and 1b
A half mirror 400 having a wavelength selection characteristic that reflects the light from the light source 1a and transmits the light from the light source 1b is arranged in front of the collimator lens 2. This light source 1a, 1
The b, the half mirror 400, the collimator lens 2 and the like constitute a target projection unit A that projects the measurement target onto the detection element 5.

On the other hand, in the mask plate 4, as shown in FIG. 9B, the mask patterns P ₁ and P ₂ (measurement targets) are constituted by wavelength selective transmission type filters, and the large mask pattern P ₁ is the light source 1b. A small mask pattern P ₂ that can only transmit light from the crab
Is configured so that only light from the light source 1a can be transmitted. It should be noted that the 401 portion, which is not shaded, naturally blocks both light from the light sources 1a and 1b.

Moreover, by switching the switch 71, the light sources 1a and 1b are selectively emitted, and the mask patterns P ₁ and P ₂ are emitted.
Light from the lens to be inspected L passes through either of the
It will be projected on D5.

[Fifth Embodiment] A fifth embodiment of the present invention shown in FIG. 10 is one in which a relay lens 500 is arranged between the lens holder 3 and the mask plate 4 (measurement target). According to this, the mask plate 4 and the area CCD 5 are actuated by the relay lens 500 so as to be located at their optical conjugate positions 4'and 5 '.

[0033]

As described above, according to the present invention, in the lens meter having the target projecting means for projecting the measuring target onto the light detecting means, the measuring target projected onto the light detecting means is measured. Since the identification means for distinguishing is provided, the type or shape of the measurement target projected on the light detection means can be changed to “a small lens of a multifocal lens or a near-use designation part or software of a progressive multi-point lens. It is possible to know whether the target is a visual target such as a contact lens or a progressive contact lens, or a standard visual target for a lens to be inspected.

[Brief description of drawings]

FIG. 1 is an optical layout diagram showing a first embodiment of an auto lens meter of the present invention.

2A is a plan view showing a configuration of a mask plate 4 of the first embodiment, and FIG. 2B is a view showing an example of a projection pattern on a detecting means.

FIG. 3 is a diagram showing another example of a mask pattern.

FIG. 4 is a diagram showing still another example of a mask pattern.

FIG. 5 is a diagram showing still another example of a mask pattern.

FIG. 6A is a plan view showing the structure of a mask plate according to a second embodiment of the present invention, and FIG. 6B is a vertical mid-sectional view thereof.

FIG. 7 is a sectional view showing a third embodiment of the present invention.

FIG. 8A and FIG. 8B are plan views showing the configuration of the light shielding plate of the third embodiment.

FIG. 9A is an optical layout diagram showing a fourth embodiment of the present invention,
(B) is a diagram showing a configuration of a mask plate of the fourth embodiment.

FIG. 10 is an optical layout diagram showing a fifth embodiment of the present invention.

[Explanation of symbols]

1, 1a, 1b ... Light source 2 ... Collimator lens 3 ... Lens pedestal 4 ... Mask plate (measurement target) 5 ... Detector (light detection means) 41, 42 ... Pattern electrode 40 ... Auxiliary lens pedestal 71 ... Switch 242, 243 ... light shield portion 302 ... liquid crystal shutter L ... test lens P _1, P ₂ ... mask pattern (measured optotypes)

Claims (1)

[Claims] 1. A lens meter having an optotype projecting means for projecting a measurement optotype onto a light detection means, wherein an identification means for identifying the measurement optotype projected onto the photodetection means is provided. Lens meter characterized by.