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Патент USA US3045134

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July 17, 1962
Filed Feb. 21, 1958
2 Sheets-Sheet 1
July 17, 1962
Filed Feb. 21, 1958
2 Sheets-Sheet 2
United States Patent ()??ce
Patented July 17, 1952
and scope of this invention reference can be had to the
Harry de L. McKinlay, Jr., Glenview, Ill., assignor to
following detailed description, taken together with the
accompanying drawings, in which:
FIGURE 1 is a view, in front elevation and at full
size, of an eight millimeter camera in which the present
Bell & Howell Company, Chicago, 111., a corporation
of Illinois
invention is embodied;
Filed Feb. 21, U58, Ser. No. 716,695
3 Claims. (Cl. 250-226)
This invention relates, generally, to light responsive
FIGURE 2 is a view, at an enlarged scale, taken gener
ally along the line 2—2 of FIGURE 1;
FIGURE 3 is a horizontal sectional view taken gener
means and it has particular relation to means for control
ling the light impinging on a photoelectric cell from dif
ferent sources of light and it constitutes an improvement
over the invention of copending application Serial No.
677,865,‘ ?led August 13, 1957, now Patent No. 2,841,064,
issued July 1, 1958, and assigned to the assignee of this 15
ally along the line 3——3 of FIGURE 2, the photoelectric
cell being shown in spaced relation to the back grid to
illustrate the manner in which it is assembled in the case;
FIGURE 4 is a perspective view, at double scale, show
ing the relationship between the photoelectric cell, light
?lter therefor and the back and front grids located on
opposite sides of the ?lter; and
In the use of a photographic camera provided with
FIGURE 5 is a curve which demonstrates certain
a photoelectric exposure control, it is desirable that the
characteristics of the ?lter.
exposure control function properly with a daylight type
Referring now particularly to FIGURES l, 2 and 3
of color ?lm and also with an arti?cial or tungsten light 20 of the drawings, it will be observed that the reference
type of color ?lm having a higher emulsion speed than
character 10‘ designates, generally, a photographic movie
the daylight type. Examples of such ?lm are “Koda
camera of the type described in more detail in the ap
chrome” daylight type for daylight exposure and having
plication referred to hereinbefore. The camera 10 in
an emulsion speed rating of ASA 10 and “Kodachrome”
cludes a camera housing and on the front side thereof
type A for arti?cial or tungsten light exposure and having 25 a case 12 is located and held in position by screws 13.
an emulsion speed rating of ASA l6.
Within the case 12, as shown in FIGURES 2 and 3,
Noting that the diaphragm opening of the photographic
there is a photoelectric cell that is shown, generally, at
lens of a photoelectric exposure control is varied in
14 and is preferably of rectangular con?guration.
versely with respect to variance of light to which the
As shown in FIGURE 4, the photoelectric cell 14
photoelectric cell of the control is subjected, it is the 30 is provided with terminals 15 which are connected, as
present practice to provide an adjustable shutter which, in
described in the application above mentioned, to the
one position, cuts off light from a predetermined por
winding of a galvonometer type mechanism which is
tion of the light receiving area of the photoelectric cell
arranged to control mechanically the diaphragm opening
in order to provide proper functioning of the exposure
in accordance with the light energy received by the photo
control for the daylight type of ?lm. and which, in an
electric cell 14.
other position, permits a greater predetermined portion
It is desirable to provide for using the camera 10 either
of the light receiving area of the photoelectric cell to
in daylight or in arti?cial light such as tungsten light.
receive light and provide proper functioning of the ex~
It was pointed out above wherein different ?lm speeds
posure control for the arti?cial or tungsten light type of
‘are used for these different conditions and that the dif
?lm. While such a shutter is effective, it requires manual 40 ference in conditions was accommodated by employing
adjustment and, through inadvertence, may be positioned
an adjustable shutter to vary the light energy impinging
improperly for the type of ?lm being exposed.
on the photoelectric cell :14. Since this required the op
It is one of the objects of the invention to provide
erator to make an adjustment and such adjustment may
means whereby a photoelectric control is automatically
be made improperly or forgotten altogether, it is desirable
accommodated for proper exposure of these dilferent
to provide other means to accomplish the same result.
types of ?lm without requiring any mechanical adjust
For this purpose a ?lter 16, generally rectangular in
ment whatsoever.
shape to conform to the shape of the photoelectric cell
Other objects of this invention include: Transmitting
14, is employed. It is interposed between the light sensi
to the photoelectric cell only that portion of the light
tive portion of the photoelectric cell 14 and the light which
spectrum that is common to daylight and the arti?cial 50 is re?ected from the object being photographed. The ?lter
light impinging on the photocell; to prevent transmission
16 is chosen so that it will remove from daylight that por
of that portion of the spectrum of daylight that is absent
tion of the spectrum which is absent in tungsten light.
in tungsten light; transmitting to the photoelectric cell
The curve 17, shown in FIGURE 5, illustrates a preferred
about the same amount of energy from either daylight or
light transmission characteristic for the ?lter 16. Here
tungsten light under comparable conditions; applying to
percent of transmission is plotted as ordinates against wave
the photoelectric cell light having wave lengths above a
lengths in milli-microns as abscissae. The ?lter 16, bar
predetermined minimum Wave length, such as 560 milli
overall absorption, obstructs transmission only of the
microns; to limit the light impinging on the photoelectric
shorter wave lengths, as shown in FIGURE 5, which are
cell substantially to that which is normal thereto; and to
lacking or present in only negligible amounts in tungsten
provide horizontal and vertical grid elements on opposite
but which constitute a considerable portion of day
sides of the ?lter in order to thus limit the light.
Thus, the ?lter 16 reduces the energization of the
Other objects of this invention will, in part, be obvious
photoelectric cell 14 as it is exposed to daylight so that
and in part appear hereinafter,
This invention is disclosed in the embodiment thereof
shown in the accompanying drawings and it comprises
the features of construction, combination of elements
the same area of the photoelectric cell may be exposed to
daylight as with arti?cial light While providing the rela
tively large diaphragm opening that is required by the
slow emulsion speed of daylight color ?lm.
By em—
and arrangement of parts that will be exempli?ed in the
construction hereinafter set forth and the scope of the
ploying the ?lter 16 having the light transmitting charac
application of which will be indicated in the appended
for mechanically reducing the exposed area of the photo
electric cell 14 for daylight ?lm.
The manner in which the ?lter 16 is mounted in the
For a more complete understanding of the nature
teristics as described, it is unnecessary to employ a shutter
the photocell means to adapt the photocell means auto
case 12 is important. In FIGURES 2, 3 and 4 it will be
matically to both outdoor ?lm having a ?rst predetermined
observed that it is located between a back grid, shown gen
?lm speed and indoor ?lm having a second predetermined
erally at 20, and a front grid, shown generally at 21.
?lm speed higher than said ?rst predetermined ?lm speed
These grids are formed of molded plastic material and
are generally rectangular to conform to the rectangular C11 and comprising a ?lter adapted to transmit to the photo
cell means all portions of the visible spectrum below about
shapes of the photoelectric cell 14 and ?lter 16. It is
?ve-hundred-sixty milli-microns so that the lower portions
desirable that only light normal to the photoelectric cell
of daylight spectrum are absorbed and substantially all
14- be permitted to impinge thereon. In order to limit the
portions of tungsten spectrum are transmitted to the
amount of light impinging on the photoelectric cell 14
from above or below it, horizontal grid elements 22 and 10 photocell means.
2. In a camera including variable diaphragm means,
23 are formed integrally with the back and front grids
galvanometer means for driving the diaphragm means,
20‘ and 21 respectively. Light from the sides is prevented
and photocell means sensitive to substantially the entire
from impinging on the photoelectric cell 14 by vertical
daylight spectrum for regulating the galvanometer means,
grid elements 24 and 25 which likewise are formed in
the improvement for regulating the photocell means to
tegrally with the back and front grids 20 and 21 respec
adapt the photocell means automatically to both outdoor
?lm having a ?rst predetermined ?lm speed and indoor
As shown in FIGURES 2 and 3 of the drawings the
?lm having a second predetermined ?lm speed higher
back grid 21} is shouldered at 2.6 into the front grid 21
than said ?rst predetermined ?lm speed and comprising a
while the latter is shouldered at 27 into a generally rec
?lter adapted to transmit to the photocell means all por
tangular opening 28 that is provided in the case 12. Be
tions of the visible spectrum below about ?ve-hundred
tween the back and front grids 20 and 21 a groove 29 is
sixty milli-microns so that the lower portions of daylight
formed for receiving the ?lter 16. The assembled back
spectrum are absorbed and substantially all portions of
and front grids 2t) and 21 with the ?lter 16 therebetween
tungsten spectrum are transmitted to the photocell means.
are resiliently held in position by leaf springs 30. As
3. In a camera including an adjustable diaphragm,
shown in FIGURE 2 a compact arrangement is provided
electromotive means for adjusting the diaphragm, a photo
when the assembly is complete in the case 12 with the
electric cell for controlling the electromotive means and
photoelectric cell 14 juxtaposed to the rear portion of the
subject to light from a scene to be photographed, the
back grid 20 while the ?lter 16 is interposed between the
combination therewith of a ?lter interposed between the
back and front grids 20‘ and 21 and the latter is located
cell and the scene to be photographed and adapted to
in the opening 28 and projects therethrough.
transmit to the cell substantially all portions of the visible
When the camera 10 is used either in daylight or in
spectrum above about ?ve-hundred-sixty milli-microns and
tungsten light no adjustment is required insofar as the
to absorb substantially all portions of the visible spec
energization of the photoelectric cell 14 is concerned to
trum below about ?ve-hundred-sixty milli-microns so that
accommodate these different conditions. By employing
the ?lter 16, which ‘preferably approximates a Wratten ‘ the lower portions of daylight spectrum are absorbed and
substantially all portions of the tungsten spectrum are
No. 8 ?lter, the portion of the spectrum of light which
transmitted to the photoelectric cell, whereby the camera
is absent in tungsten light is ?ltered out of daylight and
is adapted to use both indoor and outdoor type ?lms.
thus the photoelectric cell 14 is subjected to the same light
energy under comparable conditions. The ?lter 16 pref
erably is formed of a suitable plastic, such as methyl
References Cited in the ?le of this patent
methacrylate resin which is provided with the proper color
to give the desired operating charactertistics.
Since certain changes can be made in the foregoing con
struction and different embodiments of the invention can
be made without departing from the spirit and scope there
of, it is intended that all matter shown in the accompany
ing drawings and described hereinbefore shall be in
terpreted as illustrative and not in a limiting sense.
What is claimed as new is:
1. In a camera including variable exposure control
means, galvanometer means for controlling the variable
exposure control means, and photocell means sensitive
to substantially the entire daylight spectrum for regulating
the galvanometer means, the improvement for regulating
Coblentz ____________ __ June 12, 1923
Riszdorfer ____________ __ Sept. 25,
Touceda et al _________ __ Nov. 26,
Tonnies ______________ __ Dec. 31,
Fleisher et al. __________ __ Oct. 5,
Gittus ________________ __ June 3, 1952
Rebikoff ____________ __ Nov. 23, 1954
Stimson et al. ________ __ Dec. 27, 1955
Taylor ______________ __. May 1, 1956
Bagby et al. ___________ _ July 1, 1958
Mcllvaine ____________ __ Apr. 28, 1959
Smith et al. __________ .._ Apr. 24, 1951
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