Photography – With object illumination for exposure – Having exposure synchronizer
Reexamination Certificate
2001-08-06
2003-11-25
Adams, Russell (Department: 2851)
Photography
With object illumination for exposure
Having exposure synchronizer
C396S177000
Reexamination Certificate
active
06654558
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an electric flash which carries out a slave flash.
Further, this invention relates to a connector which connects an accessory shoe of a camera and an electric flash to allow the electric flash to carry out the slave flash.
2. Description of the Related Art
Conventionally, multiple flash photography using the slave flash has been commonly known.
FIG. 10
is a view showing the multiple flash photography.
In
FIG. 10
, a camera
92
is arranged with a predetermined shooting distance from a subject
91
. A master-side flash
93
is connected to the camera
92
.
Meanwhile, an electric flash
94
on a slave side is independently arranged at a position for additionally illuminating the subject
91
. An optical detecting part
95
for detecting light of the master-side flash
93
is provided at the electric flash
94
on the slave side.
FIG. 11
is a view explaining the operation of the above slave flash.
First, the master-side flash
93
starts flash light emission according to the control of the camera
92
. The optical detecting part
95
receives the flash light.
When a received light quantity exceeds a detection level of a flash start (LA shown in FIG.
11
), the optical detecting part
95
detects a flash start of the master-side flash
93
. The electric flash
94
on the slave side starts the flash light emission in synchronization with the detection timing.
Meanwhile, the camera
92
measures a reflected light quantity of a film (or an imaging element). When the camera
92
determines that an exposure reaches an adequate level based on the reflected light quantity, it stops the flash of the master-side flash
93
. As a result of this, a flash quantity of the master-side flash
93
attenuates quickly and the received light quantity of the optical detecting part
95
decreases.
When the received light quantity falls below a detection level of a flash stop (LB shown in FIG.
11
), the optical detecting part
95
detects a flash stop of the master-side flash
93
. The electric flash
94
on the slave side stops the flash light emission in synchronization with the detection timing.
Incidentally, it is assumed that the master-side flash
93
and the electric flash
94
are arranged close to each other with the objective of increasing the flash quantity (the so-called guide number) and the like. When these are arranged closely like the above, there is a high possibility that the optical detecting part
95
obstructs a light path of the master-side flash
93
, which may cause a disadvantage such as a shadow cast over the subject.
Further, the aforesaid electric flash
94
detects flash start of the master-side flash
93
when the received light quantity reaches the detection level LA. Hence, the flash start of the slave flash falls behind the flash start of the master-side flash
93
. This delay of the slave flash causes a change in an illumination ratio between the master side and the slave side, as flash time shortens.
Moreover, there is a possibility that the flash of its own is detected by the aforesaid electric flash
94
. In this case, an optical detection signal of the optical detecting part
95
is likely to be saturated, which may cause disadvantages such as the delay of the detecting operation of the flash stop, and the impossibility of detecting the flash stop.
Furthermore, there is a possibility that the aforesaid electric flash
94
detects light from the outside and flashes erroneously. In this case, it is necessary to wait for a while until the electric flash
94
is ready for the next flash, which may cause a disadvantage of missing important photo opportunities or the like.
SUMMARY OF THE INVENTION
In view of the above disadvantages, it is an object of the present invention to provide an electric flash which is disposed close to a master-side flash and able to carry out a good slave flash.
Further, it is another object of the present invention to realize a slave flash with the same principle as the electric flash of the present invention by contriving a connector for connecting an accessory shoe of a camera with a conventional electric flash in order to.
Hereinafter, the present invention will be explained.
(1) The electric flash according to the present invention is an electric flash disposed for use close to a master-side flash whose flashing is controlled by a camera, comprising a flash source for emitting flash light to illuminate a subject, a trigger noise detecting part for detecting trigger noise generated from the master-side flash, and a flash control part for controlling the flashing of the flash source in synchronization with the trigger noise detected by the trigger noise detecting part.
Generally, the master-side flash emits the trigger noise to the outside under the flash control (flash start, for example) of the master-side flash. This kind of trigger noise is weak and its radial direction is wide. Hence, it is impossible to detect the trigger noise at positions distant from the master-side flash because it is buried in surrounding electromagnetic waves.
Meanwhile, the electric flash according to the present invention is disposed for use close to the master-side flash. Therefore, the trigger noise detecting part included therein can detect the trigger noise excellently. The flash control part controls the flash source in synchronization with detection result of the trigger noise, and carries out the slave flash.
As described above, unlike the conventional art the electric flash according to the present invention does not need to receive the light of the master-side flash. Therefore, the electric flash need not be disposed unnecessarily in a light path of the master-side flash so that it is unlikely to occur that the light of the master-side flash is erroneously interrupted.
Moreover, the trigger noise is generated at the time of controlling the flashing of the master-side flash. Therefore, it is easy to detect the flash start more quickly than the conventional example which detects the start after the flash light emission is actually started. Hence, according to the present invention, it is possible to easily realize the electric flash which carries out the slave flash almost simultaneously with the flash light emission of the master-side flash.
(2) According to another aspect of the present invention, the flash control part of the above electric flash (1) stops the flashing of the flash source in synchronization with the trigger noise detected by the trigger noise detecting part after the start of the flashing of the flash source.
It is determined that the trigger noise detected after the start of the slave flash as described above is caused by the flash stop of the master-side flash. Hence, the flash control part stops the slave flash in synchronization with the trigger noise.
This operation enables the slave flash to be stopped in accordance with the timing of the flash stop of the master-side flash.
(3) According to still another aspect of the present invention, the above electric flash (1) further comprises a detection invalid part for invalidating the detection of the trigger noise in synchronization with the control timing of the flashing of the flash control part, and preventing a malfunction of the flash control part due to spontaneous noise.
In the conventional example, the malfunction is caused by receiving the slave flash of its own. Similarly, it is also concerned that the malfunction occurs due to spontaneous noise (trigger noise generated from the electric flash itself) in the present invention.
However, the trigger noise on the master side and the trigger noise on the slave side are deviated in terms of time, and hence it is possible to distinguish the source of the trigger noise on a time basis.
The detection invalid part with the above structure invalidates the detection of the noise (that is, the spontaneous noise) according to the control timing of the slave flash. Thereby, it is possible to remedy a defect that the slave flash operation is disturbed by
Chen Zhaoxiang
Hagiuda Nobuyoshi
Adams Russell
Nikon Corporation
Oliff & Berridg,e PLC
Smith Arthur A
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