JPH0446371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic lens meter for measuring the refractive power of various lenses such as eyeglass lenses.

[Conventional technology]

In the past, various improvements have been made to automatic lens meters in order to make them mechanically simpler and easier to manufacture, adjust, etc., as well as to shorten measurement time and improve measurement accuracy.
A lens meter shown in Japanese Patent No. 168137 was provided.

The lens meter transmits a measurement light flux through a lens to be tested, receives the transmitted light flux by two pairs of photoelectric conversion elements, and also inserts a slit aperture, which all has the same inclination angle with respect to the scanning direction, in two known directions. The refractive power was measured by selectively scanning and chopping the transmitted light beam, and inputting the phase difference between the output signals between the photoelectric conversion elements of each pair to a calculation means.

An image splitting prism, an image matching prism, or the like is used as a means for scanning the slit opening in two known directions alternatively.

However, the lens meter shown in the above-mentioned Japanese Patent Application Laid-open No. 57-168137 requires an image splitting prism, an image matching prism, etc., as described above, and is not effective in terms of light quantity, resulting in a decrease in measurement accuracy. However, it had the disadvantage that it could not be simplified very much, nor was it easy to manufacture.

[Problem that the invention seeks to solve]

The present invention eliminates the drawbacks of the prior art described above, and provides a lens meter that does not require the use of an image splitting prism, an image matching prism, etc., has a simple mechanism, is advantageous in terms of light quantity, and has good measurement accuracy. That is.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention transmits a measurement light flux through a test lens, receives the transmitted light flux by two or more pairs of photoelectric conversion elements, and sequentially scans a plurality of slit openings to In the apparatus for measuring the refractive power of the lens to be tested based on the phase difference of output signals between the photoelectric conversion elements constituting each pair by sequentially chopping the light beam, each of the plurality of slit apertures is An output device is provided to set the inclination angle of the slit aperture to two or more different known angles, and to output a discrimination signal for the inclination angle of the slit aperture that is chopping the transmitted light beam, and to output a discrimination signal between the discrimination signal and the phase difference. The refractive power is obtained by inputting the refractive power into the calculation means.

[Effect]

According to the present invention, the inclination angle of each slit opening for sequentially chopping the transmitted light beam of the test lens is
Since the slit openings are made to have two or more different known angles with respect to the scanning direction, by scanning in one direction, the slit openings, which all have the same inclination angle with respect to the scanning direction, can be selected between two known directions. This is substantially equivalent to scanning the lens and chopping the transmitted light beam of the lens to be inspected.

Therefore, according to the present invention, there is no need for conventional image splitting prisms, image matching prisms, etc.
The mechanism is simple, the amount of light is advantageous, and the measurement accuracy is improved.

〔Example〕

Hereinafter, the present invention will be explained in detail based on one embodiment.

FIG. 1 is a block diagram of the optical system of this embodiment.

In the same figure, 1 is an LED light source that emits a measurement luminous flux, and five LEDs 1a, 1b, 1c, 1d, 1e
It consists of As shown in the second diagram showing the LL arrow view in FIG. 1, a pair of LEDs 1a, 1
b is arranged on a line making an angle of +45° with respect to the line perpendicular to the measurement optical axis O in the plane of the drawing 1, and symmetrically to the measurement optical axis O, and the other pair of LEDs 1c and 1d are arranged in the plane of the drawing 1. arranged on a line making -45° to a line perpendicular to the measurement optical axis O and symmetrically to the measurement optical axis O,
The LED 1e is arranged on the measurement optical axis O. However, the arrangement of the LEDs 1a to 1d can be changed as appropriate. In the case of the embodiment shown in the drawings, the LEDs 1a to 1d are involved in measuring the refractive power of the lens 7 to be tested, and the LED 1e is involved in measuring the amount of prism of the lens 7 to be tested, as will be described later. Therefore, when measuring only the refractive power of the lens 7 to be tested, the LED 1e is not particularly necessary.

Further, 2 is a condenser lens that focuses the luminous flux from the LED light source 1 onto an aperture 4. Reference numeral 3 denotes an aperture stop, which has apertures 3a to 3e corresponding to the LEDs 1a to 1e of the LED light source 1, respectively, as shown in FIG. Reference numeral 4 denotes a diaphragm having an aperture 4a, which has a shape as shown in the fourth figure showing its plan view. Further, 5 indicates the apertures 3a to 3e of the aperture stop 3,
This is an imaging lens that forms an image on the surface of the lens holder 6 that holds the lens 7 to be tested. In addition, the above aperture 4
is preferably located near the focal point of the imaging lens 5.

Therefore, the light beam emitted from the LED light source 1 is condensed by the condenser lens 2 onto the aperture 4a of the diaphragm 4,
After passing through the apertures 3a to 3e of the diaphragm 3, further passing through the aperture 4a of the diaphragm 4, and passing through the imaging lens 5, it becomes a substantially parallel light beam and forms an image corresponding to the apertures 3a to 3e on the inner surface of the test lens 7. The light then passes through the lens 7 to be tested.

For the purpose of explanation, the above LED light source 1, condenser lens 2, aperture diaphragm 3, diaphragm 4, imaging lens 5,
If the lens holder 6 and the test lens 7 are called a measurement light flux optical system 8, the measurement light flux optical system 8
may have other configurations. For example, instead of the measurement beam optical system 8 in FIG. 1, a measurement beam optical system having a configuration as shown in FIG. 5 or 6 may be used. In FIGS. 5 and 6, the same components as in FIG. 1 are designated by the same reference numerals. In FIG. 5, 9 is a filament and 10 is a collimator lens. Further, in FIG. 6, 11 is a point light source, 12 is a collimator lens, and 13 is an aperture diaphragm attached to a lens holder 6 configured similarly to the aperture diaphragm 3 in FIG.

Further, in FIG. 1, reference numeral 14 denotes a collimator lens, and it is desirable that one focal point is located near the surface of the lens holder 6, and the other focal point is located near the surface of the rotating chopper 15. The rotary chopper 15 has a plurality of slit openings 16a, 16 which will be described in detail later.
b, and the rotary chopper 15 is rotated in one direction by a motor 17.

Further, reference numeral 18 denotes an imaging lens that forms an aperture image formed on the surface of the lens holder 6 onto the light receiving surface of the photoelectric converter 19. On the light-receiving surface of the photoelectric converter 19, there is a seventh mark shown in the NN arrow view in FIG.
As shown in the figure, apertures 3a to 3e of the aperture stop 3
Photoelectric conversion elements 20a to 20 corresponding to
e is provided.

Therefore, the light beam based on the apertures 3a to 3e of the diaphragm 3 that has passed through the test lens 7 as described above is focused by the collimator lens 14 onto the surface of the rotating chopper 15, and is chopped by the rotating chopper 15. Furthermore, the rotating chopper 15
The light beam transmitted through the slit opening 16a or 16b is projected onto the photoelectric conversion elements 20a to 20e.

In the present invention, the inclination angles of each of the plurality of slit openings for chopping the transmitted light beam of the test lens 7 with respect to the scanning direction are set to two or more different known angles.

In the case of the embodiment shown in the drawings, as shown in FIG. 8 showing a developed view of the rotary chopper 15, the inclination angle of the first slit opening 16a with respect to the rotational direction X of the rotary chopper 15 is +45°, and the inclination angle of the second slit opening 16b is -. It is said to be 45°. However, other angles may be used, or three or more different known angles may be used. Further, the slit openings may be arbitrarily arranged. For example, instead of the rotating chopper 15, a rotating chopper 21 with a changed arrangement of the first slit opening 16a and the second slit opening 16b as shown in FIG. 9 may be used. It is okay to use. Incidentally, FIG. 9 shows a developed view of the rotary chopper 21. Note that it is actually preferable that the shape of the slit opening has a constant inclination angle.

Further, in the present invention, an output device 22 is provided which outputs a determination signal (hereinafter simply referred to as a determination signal) indicating at what angle of inclination the slit opening is chopping the transmitted light beam of the test lens 7.

In the embodiment shown in the drawings, the output device 22 uses, for example, a sensor that detects the rotation angle of the rotary chopper 15 corresponding to the position of the slit openings 16a, 16b.

In addition, in the case of the drawing embodiment, as shown in the 10th figure,
Photoelectric conversion elements 20a, 20b, 20c and 20d
are connected to waveform shaping circuits 23a, 23b, 23c and 23d, respectively. A pair of photoelectric conversion elements 2
A pair of waveform shaping circuits 23a and 23b that shape the waveforms of output signals 0a and 20b are each connected to a first phase difference measurement circuit 24, and a pair of photoelectric conversion elements 20
A pair of waveform shaping circuits 23c and 23d that shape the waveforms of the output signals 23c and 20d are each connected to a second phase difference measuring circuit 25. First phase difference measurement circuit 2
4 and the second phase difference measuring circuit 25 are connected to an interface 29 of a microcomputer 26. The output device 22 is further connected to the interface 29 of the microcomputer 26, and a discrimination signal is input thereto. The microcomputer 26 mainly includes a microprocessor (central processing unit) 27, a memory (storage device) 28, and an interface (input/output signal processing circuit) 29, and the first slit opening 16a is connected to the test lens 7. The first point when chopping the transmitted luminous flux of
Phase difference measurement circuit 24 and second phase difference measurement circuit 25
The output of
Phase difference measurement circuit 24 and second phase difference measurement circuit 25
The outputs of the lens 7 to be tested are respectively stored at predetermined locations in the memory 28, and then calculations as described below are performed between the stored values to determine the tangential force of the test lens 7, that is, the cylindrical axis angle θ, and
The spherical surface bending force S and the cylindrical surface bending force C are calculated and the results are displayed on the display device 30.
However, in the case of the embodiment shown in the drawings, the microcomputer 26 also functions as a phase difference correction means and a prism amount calculation means, as will be described later.

Here, the reason why refractive power can be determined by calculation will be described.

If the lens 7 to be tested is not placed in the lens holder 6, the light beams passing through the apertures 3a to 3d of the diaphragm 3 will be focused at a single point 3' on the surface of the rotating chopper 15, as shown in FIGS. 11a and 11b. be illuminated.
Then, the first slit opening 16a is scanned in the direction of the arrow X as shown in FIG.
6b is scanned in the direction of arrow X as shown in FIG. 11b,
Each of the slit openings 16a and 16b tips the light beam focused on the single point 3'.

On the other hand, when the lens 7 to be tested is placed on the lens holder 6, the light beams passing through the apertures 3a to 3d of the diaphragm 3 are transmitted to corresponding points 3a' and 3b on the surface of the rotating chopper 15, as shown in FIG. 12a and b, respectively. ′、3c′、
The light is focused on 3d'. Then, the first slit opening 1
6a is scanned in the direction of arrow X as shown in FIG. 12a,
The second slit opening 16b is scanned in the direction of arrow X as shown in FIG. 12b, and each slit opening 16a, 16
b serves to chop the transmitted light flux of the lens 7 to be tested, which is focused on each of the points 3a', 3b', 3c', and 3d'.

The situations shown in FIGS. 11 and 12 are explained in the prior art section by scanning the slit apertures, which all have the same inclination angle with respect to the scanning direction, alternatively in two known directions. This is substantially equivalent to chopping the transmitted light beam.

Therefore, when the first slit aperture 16a scans and chops the transmitted light beam of the test lens 7, and assuming that the scanning speed is constant, the output signal position of the photoelectric conversion elements 20a and 20b is The value obtained from the phase difference is D ₁ and the value obtained from the phase difference between the output signals of the photoelectric conversion elements 20c and 20d is D ₂ .The second slit aperture 16b scans and chops the transmitted light flux of the test lens 7. In this case, assuming that the scanning speed is constant, D ₃ is the value obtained from the phase difference between the output signals of the photoelectric conversion elements 20a and 20b, and the phase difference between the output signals of the photoelectric conversion elements 20c and 20d is If the value obtained from is _D4 , then _D1 = S + Ccos ² θ ... D ₂ = C/2sin2θ ... D ₃ = -C/2sin2θ ... D ₄ = S + Csin ² θ ... .

Therefore, since the unknowns are C, S, and θ, and there are three measured data, D ₁ , D ₂ (=-D ₃ ), and D ₄ ,
By calculating from the above equation (or), the cylinder axis angle θ, the spherical refractive power S, and the cylindrical refractive power C can be determined.

In the case of the embodiment shown in the drawings, a scanning speed detecting means 31 is further provided for detecting the scanning speed of the slit openings 16a, 16b. The scanning speed detecting means 31 is configured to output a signal corresponding to the time required for rotating the rotary chopper 15 through a predetermined rotation angle, and the output signal is sent to the interface 29 of the microcomputer 26.
has been entered.

The microcomputer 26 is also configured to correct the phase difference between the output signals between the photoelectric conversion elements based on the output signal of the scanning speed detection means 31. That is, by focusing on the fact that the phase difference between the output signals between the photoelectric conversion elements is inversely proportional to the scanning speed of the slit openings 16a and 16b, the phase difference at the actual scanning speed is converted into the phase difference at a predetermined constant scanning speed under the same conditions. After that, the above-mentioned calculation is performed using the corrected phase difference. Therefore, the slit opening 16a,
Even when the scanning speed of the motor 16b, specifically the rotational speed of the motor 17, fluctuates, highly accurate measurement is possible in the same way as when the rotational speed of the motor 17 is kept strictly constant. Note that the above situation is exactly the same in the measurement of the amount of prism, which will be described later.

However, if the rotation speed of the motor 17 is kept strictly constant, the scanning speed detection means 31 and the microcomputer 26 do not need to function as phase difference correction means.

Furthermore, in the case of the embodiment shown in the drawings, the amount of prism of the lens 7 to be tested can be measured. That is, in addition to the photoelectric conversion element 20e described above, a light source 32 as shown in the first diagram is used as a prism amount detection sensor.
and a photoelectric conversion element 33 are provided, and the test lens 7 is not installed in the lens holder 6 (in this state, the light flux passing through the aperture 3e of the diaphragm 3 also passes through the rotating stopper 15 as shown in FIGS. 11a and 11b).
The light is focused on one point 3' on the surface. ), the photoelectric conversion elements 20e and 33 are arranged so that their output signals are generated at the same timing. However, even if they are not arranged so that their generation timings match, the phase difference between the output signals of the photoelectric conversion elements 20e and 33 is stored in advance in the memory 2 of the microcomputer 26.
8 should be memorized. The photoelectric conversion elements 20e and 33 are connected to waveform shaping circuits 34 and 35 that shape the waveforms of their output signals, respectively. Further, the waveform shaping circuits 34 and 35 each have a third
It is connected to a phase difference measuring circuit 36, and the third phase difference measuring circuit 36 is further connected to an interface 29 of the microcomputer 26. The microcomputer 26 also functions as a prism amount calculating means, and the third phase difference measuring circuit 36 when the first slit aperture 16a is chopping the transmitted light beam of the test lens 7 corresponding to the aperture 3e of the aperture 3 and the third output when the second slit aperture 16b is chopping the transmitted light flux.
The outputs of the phase difference measuring circuit 36 are respectively stored at predetermined locations in the memory 28, and then calculations as described below are performed between the stored values to calculate the amount of prism of the lens 7 to be tested, and the results are also displayed on the display device 30. It is something that forces you to do something.

Here, the reason why the amount of prism can be determined by calculation will be described.

Now, when the test lens 7 is installed in the lens holder 6, and if the test lens 7 does not have a prism amount, the light flux passing through the aperture 3e of the diaphragm 3 will be as shown in FIGS. 12a and 12b. The light is focused on a point 3e' on the surface of the rotating chopper 15 (the same point as the point 3' in FIGS. 11a and 11b). The light beam focused on the one point 3e' is also stopped by the slit openings 16a and 16b in the same manner as described above. In this case, the photoelectric conversion element 2
No phase difference occurs between the output signals of 0e and 33.

On the other hand, if the lens 7 to be tested has a prism amount, the light beam passing through the aperture 3e of the diaphragm 3 will be directed to one point 3e' in FIGS. 12a and b, as shown in FIGS. 13a and b. The light is focused on a point 3e'' shifted by an amount corresponding to the amount of the prism.Then, the first
The slit opening 16a is scanned in the direction of the arrow X as shown in FIG.
The beam is scanned in the direction of the arrow X as shown in FIG. The condensing points of the light beams that have passed through the apertures 3a to 3d of the diaphragm 3 are omitted. Therefore, in this case, even though the phase of the output signal of the photoelectric conversion element 33 is always constant, Since the phase of the output signal of the photoelectric conversion element 20e is delayed or advanced in proportion to the amount of prism, the phase difference between the output signals of the photoelectric conversion elements 20e and 33 produces a value corresponding to the amount of prism.

Therefore, when the first slit aperture 16a scans and chops the transmitted light beam of the test lens 7 corresponding to the aperture 3e of the diaphragm 3, and assuming that the scanning speed is constant, the photoelectric conversion element 20e , 33 is the value obtained from the _phase difference between the output signals of the second slit opening 16b.
If D ₆ is the value obtained from the phase difference between the output signals of the photoelectric conversion elements 20e and 33 when the above-mentioned transmitted light beam is stopped, the prism amount P of the test lens 7 is P=√ ₅ ² + ₆ ² ....

As a result, the unknown quantity is P and the measured data is
Since there are two, D ₅ and D ₆ , the prism amount P can be determined by calculating from the above equation.

The operation of the present invention having the above configuration will be explained below.

After placing the lens 7 to be tested on the lens holder 6, a measurement switch (not shown) is turned on to start measurement.

When the first slit aperture 16a is chopping the transmitted light beam of the test lens 7, the microcomputer 26 determines the state and determines the phase difference data obtained from the phase difference measurement circuits 24, 25, 36 (measured many times). (generally, an average value is used) is stored at a predetermined location in the memory 28. Furthermore, when the second slit aperture 16b is chopping the transmitted light flux of the test lens 7, the microcomputer 26 determines the state and stores the phase difference data obtained from the phase difference measuring circuits 24, 25, and 36 in its memory. 28 different predetermined locations. Incidentally, the scanning speed data of the slit opening 16a or 16b corresponding to each of the above-mentioned phase difference data is also stored at a predetermined location in the memory 28 from the scanning speed detecting means 31.

Next, the microcomputer 26 calculates the phase difference data from the above phase difference data and the scanning speed data (values stored in the memory 28) at the slit opening 16a or 16 under the same conditions.
b is corrected to the phase difference when the scanning speed is a predetermined constant speed, and then based on the corrected phase difference data, it is calculated by formula ~ or formula, and the refractive power of the test lens 7, that is, the cylinder Axial angle θ, spherical refractive power S, cylindrical refractive power C,
Further, the prism amount P is determined, and the result is displayed on the display device 30.

However, the expression ~
Alternatively, if calculations are performed based on formulas, the calculations may take time, or the constants may change depending on the arrangement of the optical system. Therefore, in an actual device, after making the device, measurements are performed using a lens whose refractive power and amount of prism are known in advance.
By storing the values of D ₁ to D ₆ in the memory 28 in correspondence with the above-mentioned known refractive power and prism amount, the above-mentioned inconvenience can be solved. The three unknowns are θ, S, and C, and the measured data is
There are three, D ₁ , D ₂ (=-D ₃ ), and D ₄ , and one unknown quantity is P, and the measured data is two, D ₅ and D ₆ , so the refractive power and prism amount are respectively Uniquely determined.

In addition, in the above explanation, the case where two pairs of photoelectric conversion elements involved in the measurement of the refractive power of the test lens 7 were provided was described, but three or more pairs may be provided, and each pair of photoelectric conversion elements The arrangement direction can be arbitrary as long as it is known.

[Effects of the Invention] According to the present invention, there is no need to use an image splitting prism, an image matching prism, etc., which were conventionally necessary. Therefore, the mechanism is simplified, manufacturing is easy and inexpensive, and the effect of improving the amount of light and measurement accuracy can be obtained.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a configuration diagram of an optical system, and FIG.
3 is a view taken along line M-M in FIG. 1, FIG. 4 is a plan view of the diaphragm in FIG. 1, and FIG.
FIG. 6 is a configuration diagram showing another embodiment of the measurement beam optical system in FIG. 1, FIG. 6 is a configuration diagram showing still another embodiment of the measurement beam optical system in FIG. 1,
Fig. 7 is a view taken along the line N-N in Fig. 1, Fig. 8 is a developed view of the rotary chopper in Fig. 1, and Fig. 9
The figure is a developed view of another rotary chopper, Figure 10 is a circuit diagram of the above embodiment, Figures 11a and b are explanatory diagrams showing the chopping state of the tested lens, and Figure 12a is
13A and 13B are explanatory diagrams showing other states of chopping of the lens to be tested, and FIGS. 13A and 13B are explanatory diagrams showing still other states of chopping of the lens to be tested. 7...Test lens, 15...Rotating chopper,
16a, 16b...Slit opening, 20a, 20
b, 20c, 20d, 20e...photoelectric conversion element,
22...Output device.

Claims (1)

[Claims] 1. A measurement light beam is transmitted through a test lens, the transmitted light beam is received by two or more pairs of photoelectric conversion elements, and a plurality of slit openings are sequentially scanned to sequentially chop the transmitted light beam. , in the apparatus for measuring the refractive power of the lens to be tested based on the phase difference of output signals between the photoelectric conversion elements constituting each pair, the inclination angle of each of the plurality of slit openings with respect to the scanning direction of the plurality of slit openings; is set at two or more different known angles, and an output device is provided for outputting a discrimination signal of the inclination angle of the slit aperture that is chopping the transmitted light flux, and the discrimination signal and the phase difference are input to the calculation means. An automatic lens meter characterized by at least obtaining refractive power. 2. The automatic lens meter according to claim 1, wherein the plurality of slit openings have two types of inclination angles, +45° and -45°, with respect to the scanning direction.