U.S. patent number 3,800,738 [Application Number 05/274,688] was granted by the patent office on 1974-04-02 for apparatus for coloring articles, for instance lens for spectacles.
This patent grant is currently assigned to Metal Lux S.p.A.. Invention is credited to Pino Tassara.
United States Patent |
3,800,738 |
Tassara |
April 2, 1974 |
APPARATUS FOR COLORING ARTICLES, FOR INSTANCE LENS FOR
SPECTACLES
Abstract
An apparatus for coloring lens for spectacles by evaporating the
coloring material under vacuum, comprises a vacuum chamber where
both the lens to be colored and the coloring material are
introduced. The material is evaporated by a resistor which is
supplied with a constant voltage by a variable transformer. The
transformer is disabled by a comparing circuit apt to compare the
intensity of coloration, continuously sensed by a photocell, with a
predetermined intensity of coloration previously set on a
potentiometer, upon said photocell sensing a sample lens.
Inventors: |
Tassara; Pino (Milano,
IT) |
Assignee: |
Metal Lux S.p.A. (Milano,
IT)
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Family
ID: |
11212605 |
Appl.
No.: |
05/274,688 |
Filed: |
July 24, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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139035 |
Apr 30, 1971 |
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Foreign Application Priority Data
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May 6, 1970 [IT] |
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24220/70 |
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Current U.S.
Class: |
118/665 |
Current CPC
Class: |
G02C
7/021 (20130101); C23C 14/547 (20130101); C03C
17/00 (20130101) |
Current International
Class: |
C03C
17/00 (20060101); C23C 14/54 (20060101); G02C
7/02 (20060101); C23c 013/08 () |
Field of
Search: |
;118/4,7,8,48-49.5,9,11
;250/219TH,226 ;356/202,203,160,161,205,206 ;117/93.3 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kaplan; Morris
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation application of application Ser.
No. 139,035, filed Apr. 30, 1971, now abandoned entitled: APPARATUS
FOR COLORING ARTICLES, FOR INSTANCE LENS FOR SPECTACLES.
Claims
What I claim is:
1. An apparatus for coloring lens for spectacles by evaporating a
coloring material under vacuum, comprising a vacuum chamber where
both the lens to be colored and said coloring material are
introduced, and heating means located inside said chamber for
heating said coloring material so as to evaporate this latter,
wherein the improvement comprises: a photometric control device for
directly sensing the transparency of the lens being colored to
generate an electric current proportional to the luminous intensity
of the lens being colored, means operable before heating said
coloring material for causing said photometric control device to
directly sense temporarily the transparency of a sample lens to
generate a reference electric current, an element presettable
according to said reference electric current and connected to an
electric power source so as to generate an electric current
proportional to the luminous intensity of the sample lens, a
comparing circuit for comparing the current generated by said
element so preset with the current generated by said photometric
control device in sensing said lens being colored, and control
means conditioned by said comparing circuit for controlling said
heating means.
2. An apparatus according to claim 1, wherein said element is
formed of a potentiometer, and wherein said photometric control
device comprises a photocell, said potentiometer being preset by
hand upon sensing said sample lens throgh said photocell.
3. An apparatus according to claim 2, wherein said operable means
comprises a shifting member shiftable between two different
positions, said member having a pair of seats, one of which is
loaded with a transparent lens and the other with the sample lens
said member when in one of said positions locating said transparent
lens in correspondence with said photocell, when in the other of
said positions locating said sample lens in correspondence with
said photocell.
4. An apparatus according to claim 1, wherein said comparing
circuit comprises a threshold circuit, which operates said control
means to switch off said heating means.
5. An apparatus according to claim 1, wherein said heating means
comprises a resistor, and a variable transformer controlled by a
wattmetric control circuit connected to said resistor for causing
said transformer to supply a constant power to said resistor.
6. An apparatus according to claim 5, comprising a reversible motor
connected to said transformer and operable in a first direction to
increase the power supplied by said transformer and in a second
direction to decrease said supplied power, said wattmetric control
circuit causing said motor to be rotated in said first direction,
said wattmetric control circuit comprising a second comparing
circuit for comparing a predetermined electric current with a
current proportional to the electric power absorbed by said
resistor to stop said motor when a predetermined power is absorbed
by said resistor.
7. An apparatus according to claim 6, wherein said second comparing
circuit comprises a first threshold circuit for operting said motor
in said first direction, said predetermined electric current being
produced by a potentiometer preset so as to generate a
corresponding threshold voltage when said predetermined power is
absorbed.
8. An apparatus according to claim 7, wherein said control means
comprises a second threshold circuit to cause said motor to rotate
in said second direction, said first and second threshold circuits
operating said motor by means of two corresponding relays.
9. An apparatus according to claim 1, comprising a pair of
crucibles, one of which is loaded with said coloring material, the
other of which is loaded with an antireflective material, a common
support for carrying both said crucibles, and means for alternately
shifting said crucibles in correspondence with said resistor.
10. An apparatus according to claim 9, wherein said common support
comprises a shaft rotatable stepwise 180.degree. and a transverse
bar carrying said crucibles at the two ends thereof and having the
middle portion secured to said shaft.
11. An apparatus according to claim 10, comprising a program
control unit for sequentially controlling the operations of said
motor and the stepwise rotation of said shaft, said control unit
controlling also at least a vacuum pump and high voltage discharge
means inside said chamber.
12. Apparatus for coloring articles, for example lens for
spectacles, by evaporating a coloring material under vacuum,
comprisng a vacuum chamber where both an article to be colored and
said coloring material are introduced, and heating means located
inside said chamber for heating said coloring material so as to
evaporate this latter, wherein the improvement comprises comparing
means for comparing the intensity of coloration of the article
being colored with a predetermined intensity of coloration, control
means conditioned by said comparing means for controlling said
heating means, said comparing means comprising a comparing circuit
for comparing a current proportional to the luminous intensity of
the article being colored and generated by a photometric control
device, with a current generated by an element preset according to
said predetermined intensity, said articles being made of glass,
and a shifting member shiftable between two different positions,
said member having a plurality of seats, one of which is loaded
with a transparent article and another with the sample article,
said member when in one of said positions locating said transparent
article in correspondence with said photometric control device and
when in the other of said positions locating said sample article in
correspondence with said photometric control device, whereby said
predetermined intensity may be determined by sensing the sample
article through said photometric control device.
Description
Applicant claims priority from corresponding Italian patent
application Ser. No. 24220-A/70, filed May 6, 1970.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for coloring articles, for
instance lens for spectacles, by evaporating the coloring material
under vacuum. More particularly, the invention relates to an
apparatus for coloring lens in the laboratory or shop of an
optician, who has to color the lens required by a customer
according to a color and an intensity of color chosen by the
customer, whereby normally very few lens at a time are to be
colored.
2. Description of the Prior Art
Known apparatus of the above type normally comprise a vacuum
chamber where the lens and the coloring material are introduced.
The coloring material is then heated by means of an electric
resistor until it is evaporated. The electric power supplied to the
resistor and the time of the process is normally controlled
manually, according to either the feeling and skill of the operator
or to some predetermined factors. The result of the process is thus
unreliable, whereas the apparatuses are intricate in operation
because of the manual knobs.
SUMMARY OF THE INVENTION
The main object of the invention is to provide an apparatus for
coloring lens obviating the above disadvantages and achieving an
absolutely constant result of the process.
Another object of the invention is to provide an apparatus of the
above type, wherein the heating of the coloring material is
automatically controlled both as intensity and as time.
According to the invention in an apparatus for coloring articles,
for example lens for spectacles, by evaporating a coloring material
under vacuum, comprising a vacuum chamber where an article to be
colored and said coloring material are introduced, and heating
means located inside said chamber for heating said coloring
material so as to evaporate, I now provide comparing means for
comparing the intensity of coloration of the article being colored
with a predetermined intensity of coloration, and control means
conditioned by said comparing means for controlling said heating
means.
It is evident that the apparatus is automatically controlled, thus
saving a considerable amount of manpower. The operator has merely
to load and unload the apparatus with the lens and the coloring
material.
In fact, whereas the loading operation requires only a few minutes,
the entire cycle of the process requires about half an hour,
whereby a single operator can load sequentially a lot of
apparatuses, the process of which is then effected
automatically.
The above characteristic will become more clear from the following
description of a preferred embodiment of the invention, and from
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic sectional vertical view of an apparatus
for coloring lens for spectacles, according to the invention;
FIG. 2 is another partial sectional vertical view of the apparatus
of FIG. 1 in an enlarged scale;
FIG. 3 is a plan sectional view taken according to a pair of
different planes of FIG. 2;
FIG. 4 is a diagram of the electric circuits controlling the
apparatus.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, the numeral 4 generically indicates the
stationary frame of the apparatus, which is formed as a box. The
frame 4 supports upwards a circular plate 5, which is the base of a
vacuum chamber 6. The plate 5 is provided with a hole 7 housing an
electrovalve, generically indicated by the numeral 11. The valve 11
is connected by means of a duct 8 to a vacuum pump 9, adapted to
generate a high degree of vacuum. The pump 9 is of any known type,
for instance of the type using the diffusion of silicon vapor, and
is therefore controlled by the valve 11.
Another pump 10 adapted to generate a low degree of vacuum, for
instance of the rotative type, is connected to an electric motor
12, whereas a group of electrovalves 13 is operable to connect
selectively the chamber 6 with the pump 10, or even with the
external space, or the pump 10 with the pump 9.
A vertical shaft 14 is rotatably mounted on the plate 5 so as to
have with this latter an airtight seal. The shaft 14 is connected
downwards with an electric motor 15 provided with a conventional
motion reducing gear mechanism. The shaft 14 is secured upwards to
the central portion of a bar 16 located inside the chamber 6. A
pair of similar crucibles 17 and 18 are secured to the two ends of
the bar 16. The crucible 17 is provided to support a coloring
material, for instance formed of a mixture of metal oxides, whereas
the crucible 18 is provided to support an antireflective material,
for instance formed of calcium fluoride.
The crucible 17 is normally located under an electric resistor 19,
which is supported by a rod of insulated material 71 crossing the
plate 5 in an airtight manner. The rod 71 projects below the plate
5 and is crossed by electric cables 75 connecting the resistor 19
to a variable transformer 33. This latter is operated by a
reversible electric motor 34 known per se, so as to increase the
power supplied by the transformer 33 when the motor 34 is rotated
in one direction and to decrease such a power when the motor 34 is
rotated in the opposite direction, the motor 34 being almost
rotated 360.degree.. The rod 71 can be refrigerated by means of a
liquid circulating through a pair of ducts 76'.
Secured to the plate 5 is also another rod 74 (FIG. 2), which is
electrically connected with a power supply unit 3 (FIG. 1). The rod
74 is adapted to generate a high voltage discharge under the
control of a suitable electric circuit not shown in the
drawing.
Secured to the plate 5 is also a frame generically indicated by the
numeral 120 and formed of a pair of vertical rods 20 connected by a
transverse bar 20'. Secured to the central part of the bar 20' is a
frusto-conic support 21 the lateral surface of which carries a
plurality of holed seats 21' (FIG. 2) each one adapted to house one
lens 22 to be colored. Located under the support 21 (FIG. 1) is
another resistor 119, which is connected by a cable 171 to the
power supply unit 3 and can be switched on to bring the chamber 6
at a predetermined temperature in a manner to be described.
The chamber is provided upwards with an eccentrically located hole
123 (FIG. 2), which connects the inner space of the chamber 6 with
a first tube 24 secured to chamber 6 in an airtight manner. A
second tube 24', secured to tube 24 by means of a pair of flanges
24", is tightly sealed downwards by means of a transparent glass
23.
The tube 24' is provided downwards with a lens 25 adapted to
concentrate a light beam downwards, in a manner known per se.
Secured to the upper end of the tube 24' is a light source formed
of a lamp 26, which is supplied with a constant voltage. The tube
24' is also provided with a pair of horizontal slots 29 located
between the lamp 26 and the lens 25. The slots 29 (FIG. 3) slidably
mount a slide 28 having a pair of similar seats 27 one of which
normally supports an uncolored lens 30, whereas the other supports
a colored sample lens 31. Normally one of lens 30 and 31 is located
within the tube 24', whereas the other is outside the tube 24' (in
FIGS. 2 and 3 the lens 30 is outside the tube 24').
The apparatus comprises a program control unit generically
indicated by the numeral 132 (FIG. 1) and cyclically operable in a
known manner for controlling the cyclic operation of the apparatus.
More particularly, the program control unit 132 comprises a shaft
32 cyclically rotatable so as to effect one revolution in half an
hour and carrying a set of cams, a cam 110 which is shown in FIG.
1. These cams are adapted to operate an associated set of switches
to control in a predetermined sequence the various operating phases
of the cycle. Particularly, a first cam 36 (FIG. 4) of the shaft 32
normally holds a switch 35 open. The switch 35 when closed causes
the reversible motor 34 to rotate in the direction to increase the
power supplied by the transformer 33. Another cam 72 of the shaft
32 controls a second switch 37, which at rest is also open. The
switch 37 when closed is adapted to cause the reversible motor 34
to be rotated in the opposite direction to progressively reduce the
power supplied by the transformer 33 until it dissappears
completely.
In order to control the power supplied by the transformer 33, the
apparatus is provided with an automatic control device which
comprises a wattmetric circuit 38 supplied through connectors A and
B with the same current and voltage supplied to the resistor 19.
The control device also comprises a comparing and amplifying
circuit, generically indicated by the numeral 39, and formed of a
node 46 connected through a resistor 47 to a potentiometer 48. This
latter is connected between a negative polarity -- Va and ground.
Connected in parallel between the node 46 and another node 49 are a
linear amplifier 50 and a feedback resistor 51.
The control device comprises also a threshold circuit generically
indicated by the numeral 40 and formed of a resistor 53 connected
between the node 49 and the base of a transistor 52. This latter is
in a non-conductive state as long as the voltage on the node 49 is
less than threshold voltage of 0.6V, but it becomes conductive when
the voltage on the node 49 reaches or is higher than 0.6 V. The
transistor 52 is connected to an electric relay R1, which controls
an electric contact r1. This latter is normally closed and is
series-connected with the switch 35.
The apparatus is provided with a second automatic control device,
comprising a photometric circuit, generically indicated by the
numeral 55. This latter is formed of a photoelectric cell 58
located within a protected tube 44 (FIG. 2), which is secured to
the plate 5 and is vertically aligned with the lamp 26. The
photocell 58 is adapted to generate a voltage proportional to the
luminous intensity received from the lamp 26 through the coloring
lens 22 and either the uncolored lens 30 or the colored sample lens
31.
The second control device also comprises a comparing and amplifying
circuit generically indicated by the numeral 56. This latter is
formed of a resistor 59 connected between the photocell 58 and a
node 60. A resistor 61 is connected between the node 60 and a
potentiometer 62 in turn connected between the negative voltage
source -Va and ground. Furthermore, connected in parallel between
the node 60 and another node 63 are a linear inverter amplifier 64
and a feedback resistor 65.
The second control device comprises also control means formed of a
threshold circuit 57 having a resistor 66 connected to the base of
a transistor 67, which is adapted to become conductive when the
voltage in the node 63 reaches, or is higher than, the threshold
voltage of 0.6 V. The transistor 67 is connected with an electric
relay R2, which controls a corresponding contact r2
series-connected with the switch 37. An alarm lamp 68 is also
connected in parallel with the relay R2 and therefore is fed by the
same transistor 67.
Finally, the apparatus comprises a manipulative knob 69 (FIG. 1)
for starting a cyclic operation of the apparatus, a knob 78 for
calibrating the photometric circuit 55 (FIG. 4) and a knob 76 (FIG.
1) for switching on the apparatus.
The coloring apparatus is operated as follows.
When some lens 22 are to be colored, the chamber 6 is removed from
the plate 5 and the lens 22 to be colored are inserted on the seats
21' (FIG. 2) of the support 21. Furthermore, the crucible 17 (FIG.
1) is loaded with the coloring material and, in the case the
antireflective treatment is required, the crucible 18 is loaded
with the antireflective material. Then, in case the crucible 17 is
not aligned with the resistor 19, the bar 16 is manually rocked so
as to exactly align vertically the crucible 17 with the resistor
19. Now the chamber 6 is placed on the plate 5 and the colored
sample lens 31 (FIG. 2) is inserted on the seat 27 of the slide 28,
which is then moved so as to bring the sample lens 31 between the
lamp 26 and the lens 25 in the position shown in FIG. 2.
Now the photometric circuit 55 (FIG. 4) is calibrated. To this end,
the apparatus is switched on by operating the knob 76, (FIG. 1)
which causes the lamp 26 to be switched on. The light beam crosses
the sample lens 31 (FIG. 2), the lens 25, and the lens 22 to be
colored, the lens 25 concentrating the beam to the photoelectric
cell 58. This latter generates thus a voltage proportional to the
received light intensity and having a positive polarity as shown in
FIG. 4.
Then, by operating the knob 78 (FIG. 1) in a suitable manner, the
potentiometer 62 (FIG. 4) is preset or adjusted so as to cause the
current in the node 60, resulting in the current crossing the
resistor 59 and in the current crossing the resistor 61, upon being
amplified by the amplifier 64 to produce on the node 63 the
threshold voltage of 0.6 V. This condition is achieved when the
lamp 68 is just switched on. The comparing and amplifying circuit
56 is thus calibrated.
To effect the coloring cycle of the lens 22 (FIG. 1), the slide 28
must be shifted so as to bring under the lamp 26 the uncolored lens
30. The lamp 26 causes now an increasing of the current crossing
the resistor 59 (FIG. 4), whereby the relay R2 is deenergized and
the contact r2 is open. Now the starting knob 69 is operated, thus
starting the cycle of the program control unit 132 (FIG. 1) and
therefore causing one revolution of the shaft 32. At rest the two
cams 36 and 72 (FIG. 4) hold the two switches 35 and 37 open,
whereby the motor 34 is standing and the transformer 33 sends no
current to the resistor 19 (FIG. 1). At the beginning of the cycle,
the shaft 32 through the cam 110 causes the motor 12 to operate the
pump 10 during about 5 minutes. The pump 10 produces into the
chamber 6 a relatively low vacuum of about 10.sup.-.sup.2 mm of
mercury. Then the shaft 32 through another cam, not shown in the
drawings, causes the resistor 119 to preliminary heat the space
inside the chamber 6. The resistor 119 will remain switched on
during the remaining part of the cycle to maintain a predetermined
temperature inside the chamber 6.
Thereafter the shaft 32 through a further cam, not shown in the
drawings, causes in a known manner the rod 74 (FIG. 2) to produce a
high voltage discharge in the chamber 6. The effect of this
discharge is to cause the gas absorbed by the walls of the chamber
6 and the plate 5 to expand and to leave the latters, thus
improving the conditions for producing the vacuum in the chamber 6.
Now the shaft 32 causes the electrovalve 11 to connect the chamber
6 with the pump 9 at high degree of vacuum, which is thus operated
during about 15 minutes. The pump 9 reduces thus the pressure in
the chamber 6 to 10.sup.-.sup.4 mm of mercury.
Now the cam 36 (FIG. 4) closes the switch 35, which causes the
motor 34 to rotate in such a direction as to cause the transformer
33 to increase the power supplied to the resistor 19. The heating
of the resistor 19 is thus started and this latter heats also the
crucible 17 (FIG. 1). The power absorbed by the resistor 19,
through the wattmetric circuit 38 (FIG. 4), produces a positive
current proportional to this power; this current is applied to the
node 46. A negative current generated by the polarity -Va through
the potentiometer 48 and the resistor 47 is also applied to the
node 46, whereby the resulting current, that is the algebraic sum
of the two currents, is applied to the amplifier 50.
At the beginning the resulting current is negative. As the electric
power absorbed by the resistor 19 increases, the negative resulting
current decreases until the current coming out from the circuit 38
becomes equal to that coming out from the potentiometer 48.
Thereafter the resulting current becomes positive and increases
progressively. The resulting current through the amplifier 50
reaches the node 49, which presents thus a voltage prportional to
the resulting current. This voltage through the resistor 53 is
applied to the base of the transistor 52.
When the voltage at the base of the transistor 52 reaches the
threshold voltage 0.6 V, the transistor becomes conductive and
energizes the relay R1. This latter opens the contact rl, thus
stopping the motor 34, whereby the transformer 33 supplies now a
constant power to the resistor 19. Since the threshold voltage
corresponds to the vaporizing temperature of the coloring material,
this latter is now evaporated, whereas the crucible 17 is now
heated by the resistor 19 at said constant power, whereby the
evaporization is effected at a constant speed. In the meantime the
cam 36 opens temporarily the switch 35. The coloring material thus
evaporated deposits on the lower surface of the lens 22, by
sublimation due to the lower temperature thereof with respect to
the crucible 17, whereby the lenses 22 are progressively
colored.
Now the cam 72 of the shaft 32 closes the switch 37, but the
relevant circuit is not closed becasue the relays R2 is deenergized
and therefore the contact r2 is open. Due to the coloration of the
lens 22 (FIG. 2), the photocell 58 reduces now progressively the
current generated thereby, according to the reduction of the light
intensity crossing the lens 22 aligned with the photocell 58. When
the lens 22 reach the intensity of coloration of the sample lens
31, the algebraic sum of the currents crossing the node 60 (FIG.
4), through the inverter amplifier 64, the node 63 and the resistor
65 produces at the base of the transistor 67 the threshold voltage
of 0.6 V and the transistor 67 becomes conductive.
Now the relay R2 is energized, thus closing the contact r2, this
latter causes the motor 34 to rotate in the opposite direction so
as to rapidly reduce the power supplied by the transformer 33. The
evaporization of the coloring material is thus stopped, while the
transistor 52 becomes conductive and deenergizes the relays R1,
whereby the contact r1 is closed again. Finally, the cam 72 of the
shaft 32 causes the switch 37 to open, whereby the motor 34 is
stopped.
The shaft 32, through another cam, not shown in the drawings,
starts now the motor 15, which rocks the shaft 14 together with
shaft the bar 16 180.degree., whereby the crucible 18 is now
brought under the resistor 19. The cam 36 closes now again the
switch 35, whereby the motor 34 is rotated so as to cause the
transformer 33 to supply an increasing power to the resistor 19.
The motor 34 is then arrested when the power supplied by the
transformer reaches the predetermined value, in the manner above
described.
Now the antireflective material is evaporated at a constant rate.
This evaporation is automatically stopped after a predetermined
delay under the control of the shaft 32, which causes the cam 36 to
open the switch 35 and the cam 72 to close again temporarily the
switch 37. The motor 34 is thus rotated as to rapidly reduce the
power supplied by the transformer 33, the shaft 14 (FIG. 1) is
rocked again 180 degrees, whereas the valve 13 is operated to
restore the pressure into the chamber 6, and the cycle of the shaft
32 is stopped. The operator raises now the chamber 6 and removes
the colored lens 22 from the support 21.
It is to be noted that the calibration of the photoelectric control
device 55 can be effected also during the coloring cycle, provided
that it will finish before the beginning of the evaporation of the
coloring material.
From the above description, it will be clear that the comparing
means 56 are adapted to compare the coloring intensity of the lens
22 with the coloring intensity of the sample lens 31 and that the
control means 57 are conditioned by the comparing means 56 for
controlling the heating means 19.
* * * * *