Photography – Camera detail – Shutter
Reexamination Certificate
2002-06-12
2004-11-16
Gray, David M. (Department: 2851)
Photography
Camera detail
Shutter
C396S488000
Reexamination Certificate
active
06817787
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a separated-blade type shutter apparatus.
2. Description of the Related Art
There are two types of a conventional focal plane shutter which includes a parallel link mechanism made up of two arms to support group of a plurality of divided blades pivotably, constructed in such a way that pivoting of these arms causes the blade group to run between a superposed state and a spread state; a long-arm type and short-arm type depending on the different methods of holding the blade group by the arms.
Here, a so-called longitudinally moving focal plane shutter that moves the blade group up and down will be explained.
First, as disclosed in Japanese Utility Model Publication No. 35-29651, a long-arm type shutter apparatus includes blade group supported by the arms pivotably at locations on the opposite side of the arm base ends across the shutter aperture. Thus, the arms are longer than the width of the shutter aperture.
Such a long-arm type shutter apparatus needs only a small arm turning angle for opening/closing the shutter aperture by the blade group, reducing the amount of displacement of the blade group by the opening/closing operation in the direction orthogonal to the blade running direction, which is advantageous to a reduction of the horizontal width of the shutter.
However, increasing the number of blades of the blade group that can be supported by the two arms to 3 or more has a disadvantage of complicating the structure and a disadvantage in a high-speed movement because of the use of a long arm, which increases inertia of the blade unit.
For this reason, with the enhancement of the shutter exposure speed and strobe tuning speed in recent years, a long-arm type shutter apparatus unfit for speed enhancement is falling into disuse.
On the other hand, a short-arm type shutter apparatus proposed to cover the disadvantages of the long-arm type is constructed in such a way that a group of a number of blades are supported by two arms on the shutter aperture edge side near the base ends of the arms pivotably without sandwiching the shutter aperture, though it is disadvantageous to reducing the horizontal width.
Moreover, the lengths of the arms are often reduced to a minimum to further reduce inertia.
Examples of this short arm type are shown in FIG.
23
and FIG.
24
.
FIG. 23
shows a shutter apparatus ready to run and
FIG. 24
shows the shutter apparatus, which has completed a running.
In these figures, reference numeral
101
denotes a board (shutter base plate) having a shutter aperture
101
a
. This base plate
101
supports base ends of a front shutter first arm
106
and a front shutter second arm
107
pivotably by axes
101
d
and
101
e.
The front shutter has a five-blade configuration and is constructed of a slit-forming blade
102
formed to open or close the shutter aperture and covering blades
103
,
104
,
105
and
105
′. The slit-forming blade
102
and covering blades
103
-
105
,
105
′ are connected to the arms
106
and
107
pivotably by means of blade swaging dowel pins
108
a
,
108
b,
108
c
,
108
d
,
108
e
,
109
a
,
109
b
,
109
c
,
109
d
and
109
e
, thus forming a parallel link.
Furthermore, this base plate
101
supports the base ends of a rear shutter first arm
114
and a rear shutter second arm
115
pivotably by axes
101
f
and
101
g
. The rear shutter has a four-blade configuration and is constructed of a slit-forming blade
110
formed to open or close the shutter aperture and covering blades
111
,
112
and
113
. The slit-forming blade
110
and covering blades
111
-
113
are connected to the arms
114
and
115
pivotably by means of blade swaging dowel pins
116
a
,
116
b
,
116
c
,
116
d
,
117
a
,
117
b
,
117
c
and
117
d
, thus forming a parallel link.
The swaging dowel pins of both the front shutter and rear shutter are positioned in sequence so as to draw a gentle arc and when the blade unit is in a superposed state to open the shutter aperture, the first arm and second arm are designed to align close to each other.
Furthermore, the external size of the blades for the front shutter necessary to secure an amount of overlapping among the adjacent blades for shielding when the blades are spread (here, equally 4 mm) and necessary to shield the shutter aperture is a little larger than the shutter aperture (here, approximately 2 mm in the vertical direction of the aperture and approximately 6.6 mm at the ends of the blades) considering an unnecessary increase of the blade inertia, (hereinafter, this shutter apparatus will be referred to as “first conventional example”).
Furthermore, Japanese Utility Model Publication No. 53-39472 discloses a shutter apparatus in a configuration that the slit-forming blade is supported by a parallel link of relatively long type arms and opening/closing of the other covering blades is driven by actions of action pins and cum grooves.
In order to form the cum grooves for drive, the covering blades are shaped in such a way that the part near the blade root protrudes toward a position away from the shutter aperture when the blades for shielding the shutter aperture are spread, (hereinafter, this shutter apparatus will be referred to as “second conventional example”).
Furthermore, according to the shutter apparatus disclosed in Japanese Patent Publication No. 60-3165 (hereinafter, referred to as “third conventional example”) and the shutter apparatus disclosed in Japanese Utility Model Publication No. 7-25787 (hereinafter, referred to as “fourth conventional example”), a protruding shape is formed near the root close to the coupling with the arm of the covering blade with the shortest running distance.
Furthermore, according to the shutter apparatus proposed in Japanese Patent Laid-Open No. 2000-180916 specification (hereinafter, referred to as “fifth conventional example”), a shielding mechanism is provided between an image-taking lens and focal plane shutter and this shielding mechanism is provided so as to freely move between an open position at which the exposure aperture is exposed by superposing the upper two of the four shields above the exposure aperture and a shielded position at which the exposure aperture is shielded by spreading the shields so as to shield the generally upper half of the exposure aperture.
Moreover, the rest of the shields are provided so as to freely move between an open position at which the exposure aperture is opened by superposing the shields below the exposure aperture and a shielded position at which the exposure aperture is shielded by spreading the shields so as to shield the generally lower half of the exposure aperture.
When the user opens the back cover of the camera, the exposure aperture is doubly covered with both the blades of the focal plane shutter and the shield of the shielding section in that order from the back side (user side). The shields, which move a smaller distance, are provided with a protruding section to be connected using an arm and pin respectively so as to be located outside the exposure aperture in a shielded state.
With a camera incorporating the above-described focal plane shutter, there is a possibility that the user may touch the blades when opening the back cover and loading a film. In the case where the user touches the blades a little stronger, the blades may penetrate the shutter aperture causing the inconvenience of disabling the camera from taking images.
For example, in the above-described first conventional example, when the back cover of the camera is opened, since the front shutter covering the shutter aperture gives priority to the alleviation of inertia while maintaining the shielding performance, the front shutter does not have a shape strong enough to hold on when pressed by a finger, etc. from the back cover and may easily penetrate the shutter aperture.
Furthermore, when generally attempting to reduce the size of the shutter, reduce the horizontal width in particular, reducing the number of the divided blades of the b
Gray David M.
Robin Blecker & Daley
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