 |
Description  |
|
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flash unit for use with a camera.
2. Description of the Prior Art
A flash unit for flash photography is ordinarily constructed as a separate
accessory which is mounted on a camera body when needed. Hence a camera
user may forget to carry a flash unit with him, and in such case must
forego its use. In order to avoid this inconvenience, cameras
incorporating flash units therein have been proposed. However, such
cameras are necessarily larger than corresponding cameras that have been
built as compactly as possible. In fact, cameras with built-in flash units
may be quite cumbersome as compared to cameras without such units.
Moreover, in manufacture, adapting a camera for built-in flash requires
extensive redesign of the camera body to receive the flash unit.
Effectively, the project requires an entirely new mechanism.
Generally speaking a compactness in size and light weight are important
features in a photographic camera. Various complicated mechanisms and
devices are housed in a very compact manner within a camera body. This
leaves little extra space therein large enough to receive a flash unit.
Thus, housing a comparatively large flash unit a compact camera.
Inevitably make the size of camera body large. Also changes in design of
various complicated mechanisms and devices built in a camera body and
development of a new mechanism are needed to prevent the size of said
camera body from becoming too large. This noises the cost of camera solely
for housing a flash device in a camera.
Also, when a flash device is housed in a camera body, said flash device
will be positioned comparatively close to the camera's objective lens. The
angle formed between a line connecting the flash device with an object and
the optical axis of the lens is then very small. When the subject is a
person, this often produces so-called "red eye." That is, the eyes of a
person photographed in a finished color print appear red.
This "red eye" phenomenon occurs while a portion of the light generated by
a flash device is reflected by eyes of the subject and back to the taking
lens when the angle formed by the line connecting a flash device with an
object and the optical axis of the taking lens is small. In other words it
appears when the position of the flash device is close to the objective
lens.
SUMMARY OF THE INVENTION
The present invention is made in view of the above and it is the primary
object of the same eliminate the disadvantages and inconveniences of a
conventional flash camera.
Another object of the present invention is to provide a flash system which
avoids the inconveniences of a camera user forgetting to carry a flash
unit without significant change in the structure of the various mechanisms
and devices housed in a camera body, and in compact manner which prevents
the size of camera body from becoming large.
Another object of the present invention is, along with said primary object,
to provide a flash unit that avoids "red eye".
According to a feature of the present invention a flash unit is mounted in
a lens cap which is an indispensable accessory of a camera.
And according to another feature of the present invention a flash device is
contained in a lens cap which is movably mounted on a pocket size camera.
Also in another example of the present invention a flash device is
contained in a lens cap which is made as attached to and detached from a
taking lens and during flash operation said lens cap is mounted on an
accessory shoe provided on a 35-mm size still camera. These and other
features of the invention are pointed out in the claims.
Other objects and advantages of the present invention will be made apparent
from the following description when read in light of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 4 show an example of the present invention applied to a pocket
size camera, wherein:
FIG. 1 is a perspective view of a camera in a state wherein a lens cap
containing a flash device is moved to a raised position relative to a
camera body,
FIG. 2 is a perspective exploded view of important parts for mechanical
coupling between a camera body and a lens cap in a camera shown in FIG. 1
and the electrical connection therebetween,
FIG. 3A is a plan view of a camera whose lens cap is brought to a raised
position against a camera body,
FIG. 3B is a plan view of a camera whose lens cap is closed down for
covering a front surface of the camera body, and
FIG. 4 is a circuit diagram to show an electric circuit of said flash
device contained in the lens cap and an electric circuit provided at a
camera body as well as connection between said two electric circuits.
Also FIGS. 5 to 7 show an example of a case when the present invention is
applied to a 35-mm size still camera, wherein:
FIG. 5 is a plan view showing a camera wherein a lens cap containing a
flash unit is attached to a photo-taking lens,
FIG. 6A is a side elevation of a lens cap shown in FIG. 5,
FIG. 6B is a schematic drawing as B--B portion of FIG. 6A is viewed.
FIG. 6C is a schematic drawing as C--C portion of FIG. 6A is viewed.
FIG. 7 is an oblique view to show the relationship among important parts
for mechancial coupling and electrical connection between a camera body
and a lens cap in the camera shown in FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
First, explanations on the present invention will be made on its
application to a pocket size camera referred to FIGS. 1 to 4.
In FIGS. 1 to 3, member 1 is a camera body. A lens cap 2 which contains a
flash device is rotationally mounted at a portion of the camera body 1.
Member 3 in the camera body 1 is a photographing window. A photo-taking
optical system contains an objective lens 4, photographing diaphragm
blades 5a and 5b, a shutter leader screen 6a and a shutter follower screen
6b.
Member 7 is a light receiving window for photo-sensing. Photo-sensing
diaphragm blades 5'a and 5'b, linked with said photographing diaphragm
bladed 5a, and 5b, as well as a photo-sensing element P are positioned
here. Member 8 is a view finder window, and member 8a is a range finder
window. Photographing window 3, light receiving window 7, view finder
window 8 and range finder window 8a are all positioned at a front surface
of the camera body casing, and are covered by the above mentioned lens cap
2 when the camera is not in use.
Member 9 is a diaphragm setting knob to set the diaphragm aperture defined
by said diaphragm blades 5a and 5b, and member 10 is a focusing knob of a
photo-taking optical system. Member 11 is a release button. All three of
these are provided on an upper surface of the camera body casing.
Also in FIGS. 3A, 3B, member 9a is a diaphragm aperture value pointer
linked with the diaphragam setting knob 9, and 10a is a range finder
pointer linked with the focusing knob 10. The system is so arranged that a
flash mark F which is used only in flash photographing is provided against
the diaphragm aperture value pointer 9a, and in a state wherein the
diaphragm setting knob 9 is so set that the diaphragm aperture value
pointer 9a matches with said mark F, shutter time is set at such
prescribed value (for example 1/60 sec.) for flash photographing, as in a
conventional camera of this type. Diaphragm blades 5a, 5b are set at the
same time as the focusing of the taking optical system in an association
with the handling of the focusing knob 10.
Member 12 is an operating knob of a power source switch is an exposure
control circuit (not shown), and is provided at a side surface of the
camera body casing.
In FIG. 2, member 13 is an axle member for attaching said lens cap 2 to the
camera body in a rotatable manner. Members 14a and 14b are two click holes
to fix the lens cap 2 at a first position (shown in FIG. 3B) wherein the
cap 2 is so closed down as covering the front surface of the camera body
and at a second position (shown in FIG. 1 and FIG. 3A) wherein the cap 2
is raised from the camera body. Members 15a, 15b and 15c are connection
terminals to retain electrical connection between the flash device
contained in the lens cap 2 and the camera body, all of which are
positioned at a part of the front surface of the camera body.
In FIG. 1, member 16 is a light emission window positioned at a part of the
lens cap casing, and a flash discharge tube L (shown in FIG. 4) at the
flash unit, is provided at said window. Light emission window 16 is
positioned near forward end part at the front surface of the lens cap
casing to prevent the afore-mentioned "red eye phenomenon" which is caused
when the angle formed by the segment of line connecting the flash
discharge tube and an object against the optical axis of the taking lens 4
becomes small in color flash photography is done using a color film.
Further in FIG. 2, member 17 is a display window to display a light
emission preparation state of the flash unit (that is a charging state of
a main capacitor in the flash unit) and is positioned at a rear surface of
the lens cap. A neon tube Ne (shown in FIG. 4) which displays a light
emission preparation state of the flash device, which, is provided at said
window.
Member 18 is an axle receiving hole to be fitted with the axle memer 13 at
the camera body 1 side, member 19 is a click ball housing hole, wherein a
click ball 20, which can be selectively dropped in click holes 14a and 14b
positioned on the camera body 1, is housed. When said lens cap 2 is fixed
to the camera body 1 as the click ball 20 is dropped in the first click
hole 14a by the biasing force of spring 21 at said first position (shown
in FIG. 3) said lens cap is so closed to cover the front surface of the
camera body 1. Lens cap 2 is also fixed at the camera body 1 as the click
ball 20 is dropped in the second click hole 14b by the biasing force of
the spring 21 at said second position (shown in FIG. 1 and FIG. 3A) so as
to raise it from the camera body 1. In FIG. 2, members 22a, 22b and 22c
are connection terminals to be contacted with connection terminals 15a,
15b and 15c at the camera body 1 side respectively, and are provided at
such position as to contact with terminals 15a, 15b, 15c only when the
lens cap 2 is set at the second position, that is, the position at which
cap 2 is raised from the camera body 1. Terminals 22a, 22b and 22c are so
respectively biased by a conductive leaf spring, not shown as projecting
outwardly.
Member 23 is an operating knob of a main switch at the flash unit and is
provided at a side of the lens cap. Member 24 is a retaining screw to
axially attach the lens cap 2 axle member 13, and is screwed to a forward
end part of axle member 13.
Also both the camera casting and the lens cap casing are formed with light
shielding material of insulating type such as plastics, etc.
The arrangement of an electric circuit as the camera body 1 and the
arrangement of an electric circuit of the flash unit housed in the lens
cap 2, also on the pattern of connection between said two electric
circuits is shown in FIG. 4.
In the flash unit housed in the lens cap 2, member S.sub.1 is a main switch
operated by the afore-mentioned operating knob 23, and VC is a booster
circuit of known type consisting of a PNP type transistor Tr, an
oscillation transformer T.sub.1, a capacitor C.sub.1, a resistor R.sub.1
and rectifying diode D member C.sub.2 is a main capacitor charged by high
voltage supplied from the rectifying diode D to accumulate light emitting
energy, while R.sub.2 members and R.sub.3 are resistors forming charging
voltage detection circuit of main capacitor C.sub.2. Ne is a neon tube to
display the charging state of the main capacitor C.sub.2 and is let when
the voltage charged at the main capacitor C.sub.2 reaches a prescribed
value (that is, such a voltage level necessary for the flash discharge
tube L to emit light) for displaying the completion of charging at the
main capacitor C.sub.2. Member C.sub.3 and T.sub.2 are a capacitor and a
trigger transformer, respectively, forming a trigger circuit, and the
secondary winding of said trigger transformer T.sub.2 is connected to a
trigger electrode of the flash discharge tube L.
Said main switch S.sub.1 is connected to an emitter electrode of said
transistor Tr at the booster circuit VC, while the connection terminals
22a and 22b are connected to the flash unit as a power source terminal of
the flash unit and the connection terminal 22c is connected to the same as
a trigger terminal, respectively.
Next in camera body 1, member E is a battery used as a power source for a
flash unit having the afore-mentioned arrangement, and S.sub.2 is a
synchronizing switch of known type to be place in ON state in association
with said shutter leader screen 6a when screen 6a makes the photographing
aperture fully opened, and said connection terminals 15a and 15b are
connected to plus side and minus side of the power source battery E,
respectively, also the connection terminal 15c is connected to the
synchronizing switch S.sub.2.
Also, while not being shown in FIG. 4, a photo-sensing circuit of known
type composed of photosensing element P and a shutter control circuit
connected to said photo-sensing circuit are provided within the camera
body 1. Also of course as the power source battery E for said flash unit,
the power source of said photo-sensing circuit and shutter control circuit
may be shared. In the drawing an arrow mark within the camera body 1 shows
said manner as a general concept.
FIG. 4 also shows a manner in which the lens cap 2 is set at said positon
(that is a position in which it is raised from the camera body 1), and as
shown in the drawing the connection terminals 22a, 22b, and 22c are
contacted to the connection terminals 15a, 15b and 15c at the camera body
1 side respectively.
In a camera having the afore-mentioned arrangement when no photography is
being done, that is, when a camera is being carried, the lens cap 2 is
closed down to the front surface part of the camera body 1 and at that
time said lens cap 2 is fixed to the camera body 1 at said position (the
above mentioned first position shown in FIG. 3B) since the click all 20 is
dropped in the first click hole 14a formed at the front surface of the
camera body casing by the biasing force of the spring 21.
And at this time the above mentioned photographing window 3, the light
receiving window 7, the view finder window 8 and the range finder windo 8a
formed at the front surface of the camera body casing will be all covered
by said lens cap of light shielding type. Therefore, in this state the
lens cap 1 performs a role of an ordinary lens cap.
Next, when photographing is being done, the lens cap 2 is rotated to right
direction around the axle member 13 until it raises from the camera body 1
to the aforementioned second position (shown in FIG. 1, FIG. 3A). Thus
each of the windows 3, 7, 8 and 8a of the camera body casing is shielded
from the light
When the lens cap 2 is set at second position, it is fixed to the camera
body 1 at said position the click ball 20 is dropped in the second click
hole 14b at the front of the camera body casing by the biasing force of
the spring 21. Simultaneously each of the connection terminals 22a, 22b
and 22c at the flash unit is contacted to the respective connection
terminals 15a, 15b and 15c at the camera body side.
First, when ordinary daylight photographing (without flash unit) is done,
the power source switch operating knob 12 of camera body casing is
switched to "ON". Then the diaphragm setting knob 9 is operated to so set
the same that the diaphragm aperture value pointer 9a matches with a mark
other than the flash mark F shown in FIGS. 3A, 3B. By this the
photographing diaphragm blades 5a, 5b and the photosensing diaphragm
blades 5'a, 5'b are set. Simultaneously a photosensing circuit (not shown)
actuates within the camera body 1 so that appropriate shutter time is
automatically determined based on the output of the photosensing element
P.
When the focusing knob 10 is operated to conduct focusing of the optical
system and then the release button 11 is depressed, the shutter leader
screen 6a runs. Simultaneously a shuter control circuit (not shown)
actuates and the action of the shutter follower screen 6b is controlled
based on the output of the photosensing circuit. This ordinary daylight
photographing can be done.
For conducting flash photographing, the main switch operation knob 23 for
the flash unit positioned on the lens cap 2 switches to "ON" and at the
same time the diaphragm setting knob 9 of the camera body 1 is so set that
the diaphragm aperture value pointer 9a matches with the flash mark F.
By this, a prescribed shutter time value suited for flash photography is
set at the shutter control circuit and the photographing diaphragm blades
5a, 5b is associated with the focusing knob 10. Thus the focusing of the
optical system is done by operating the focusing knob 10. At the same time
the diaphragm blades 5a, 5b are set within the camera body according to
the distance from an object.
Meanwhile, in the flash unit contained in the lens cap 2, since the main
switch S.sub.1 is closed by the switching of the operating knob 23, the
flash unit is connected to the power source battery E contained in the
camera body 1, thereby the charging of the main capacitor C.sub.2 and the
trigger capacitor C.sub.3 is started through the booster circuit VC.
When the voltage charged at the main capacitor C.sub.2 reaches a voltage
level sufficient for the flash discharge tube L to emit light, the neon
tube Ne is lighted, and the display window 17 positioned on the lens cap
casing shows that the flash unit has completed preparation for light
emittance.
When the release button 11 is depressed in this state, shutter leader
screen 6a runs and the photographing aperture opens by screens 6a. At this
time the synchronizing switch S.sub.2 raises closed and the electric
charge which has been accumulated at the trigger capacitor C.sub.3 is
discharge. Thus the discharge tube L triggers through the trigger
transformer T.sub.2, within the flash unit. When trigger signal is
impressed on the discharge tube L by the trigger circuit, the electric
charge which has been accumulated at the main capacitor C.sub.2 discharges
through the discharge tube L. Thus light is emitted an object is
illuminated by flash light discharged from the light emission window 16 on
the lens cap casing.
When the shutter time set by the diaphragm setting knob 9 has elapsed, the
shutter follower screen 6b is made to run by the afore-mentioned shutter
control circuit, and flash photographing is completed.
Next, explanations will be made on an example in which the present
invention is applied to a 35-mm size still camera referring to FIGS. 5 to
7.
Here, the arrangement in the example shown in FIGS. 5 to 7 is basically
identical to the arrangement in the example shown in FIGS. 1 to 4 except
that the lens cap is made to freely attach and detach from the lens.
Therefore such important components in the example shown in FIGs. 5 to 7
which are identical with those in the preceding example will be identified
by same and symbols with dash (') placed thereon, and explanations on the
same will be so omitted or simplfied as not hindering the understanding of
this example.
First in FIG. 5 a camera body is indicated by 1', and a photo-taking lens
assembly 25 consisting of an optical system (not shown), a diaphragm
setting ring 9' and a focusing ring 10'. Further a shutter time setting
ring 26 is provided in the camera body 1', while a lens cap 2' containing
a flash unit is attached to a forward end of a lens assemby 25 to perform
its original function as a lens cap.
In FIG. 7 an accessory shoe 17 made of insulating type material for
mounting of the lens cap 2' is assembled to an upper part of the casing of
the camera body 1' by screw 28. Three holes 27a, 27b and 27c are
positioned on said shoe 27 to fix the lens cap 2', wherein connection
terminals 15'a, 15'b and 15'c corresponding to the connection terminals
15a to 15c of the preceding example are positioned as conductive leaf
springs and buried at said three holes 27a to 27c.
Camera body 1' is so made that all shutter times including the shutter time
suitable to flash photographing (flash mark F) are selected by a shutter
time setting ring 26.
Especially in flash photography such diaphragm aperture value as
corresponding to a distance from an object is based on the computation of
so-called "guide number" and photographing is done by manually setting
diaphragm aperture value by the diaphragm setting ring 9'.
Next, as shown in detail in FIGS. 6A to 6C, 7, said lens cap 2' has a
display window 17' and an operating knob 23' corresponding to the display
window 17 and the main switch operating knob 23 in the preceding example
respectively formed at a front surface (refer to FIG. 6B) of its casing,
and a light emission window 16' and connection terminals 22'a, 22'b and
22'c corresponding to the light emission window 16 and the connection
terminals 22a, 22b, and 22c in the preceding example respectively at its
rear surface (refer to FIG. 6C).
And especially said connection terminals 22'a to 22'c are formed as
conductive pin members which can be fitted in the above mentioned three
holes 27a to 27c in said accessory shoe 27 respectively to fixedly secure
the lens cap 2' at the accessory shoe 27 at the camera body 1' side, and
are fixedly assembled to the rear surface of the lens caps casing.
Also what is shown as 2'a is a threaded portion used to mount the lens cap
2' to the lens assembly 25, and is threaded with a forward end part of
said lens assembly 25 as the lens cap 2' is mounted to the lens assembly
25.
In a camera having said set up, first when photographing is not done that
is when a camera is carried, the lens cap 2' is mounted to a forward end
part of the photographing lens assembly 25 by the threaded portion 2'a
thereof, and is used for protection and light shielding of the
photographing lens assembly 25 being same as in an ordinary lens cap.
Next when flash photographing is done, the lens cap 2' is removed from the
lens assembly 25 and is mounted to the accessory shoe 27 formed on an
upper part of the camera body 1' having the connection terminals 22'a to
22'c fitted with the three holes 27a to 27c of said shoe 27, respectively.
At this time the lens cap 2' is fixedly secured to said shoe by fitting of
the connection terminals 22'a to 22'c with the holes 27a to 27 c of the
shoe 27, and the flash device contained in the lens cap 2' will be
electrically connected to the power source E and the synchronizing switch
S.sub.2 contained in the camera body 1' by the contact between the
connection terminals 22'a to 22'c and the connection terminals 15'a to
15'c.
In this state after the main switch operating knob 23' in the lens cap 2'
is changed over to "ON", the shutter time setting ring 26 at the lens
assembly 25 is set at its flash mark F thereby selecting such shutter time
as suited to flash photographing, further after focusing is done by the
focusing ring 10', an appropriate diaphragm aperture value is computed
based on a distance to an object, and the diaphragm setting ring 9' is set
corresponding to said computed diaphragm aperture value for conducting
flash photographing. Also detailed function in flash photographing is
exactly same as in the case of the preceding example.
As has been explained above the present invention is so made that the flash
device is contained in a lens cap as an indispensable accessory for a
camera, and in such unique pattern of a flash device, such inconvenient
situation which could usually take place can be prevented that a camera
user forgets to carry a flash device and is compelled to give up a desire
for flash photographing, and flash photographing can be conducted at any
time necessary thus it is very convenient for a camera user.
Also such disadvantages are completely eliminated that the camera body
becomes to have large size and the design of various mechanisms and
devices housed in a camera body in compact manner needs to be changed as
has been seen in a conventional camera in which a flash device is
directely housed in a camera body.
Further, since a lens cap performs a function as a flash device together
with its original function as a lens cap, the practical value of a lens
cap is enhanced, and especially by providing a light emission window to
have a flash discharge tube mounted therein in a flash device near an end
part of a lens cap, the distance between a taking lens and a discharge
tube can be made large, thus an angle formed by a segment of line
connecting the discharge tube and an object against the optical axis of
the taking lens can be made large, therefore so-called "red eye
phenomenon" in flash photographing can be effectively prevented.
* * * * *
|
|
 |
|
 |
Description |
|
