Photography – With object illumination for exposure – Having exposure synchronizer
Reexamination Certificate
2001-09-19
2004-04-06
Adams, Russell (Department: 2851)
Photography
With object illumination for exposure
Having exposure synchronizer
C396S171000, C396S056000
Reexamination Certificate
active
06718135
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flash photography system having a main flash device (a built-in flash of a camera body, or an external flash device electrically connected to the camera body) and at least one sub-flash device (e.g., a slave flash unit) which is wireless controlled by a flash emission serving as a command signal transmitted from the main flash device.
2. Description of the Related Art
Various types of flash photography systems which have a main flash device (a built-in flash of a camera body, or an external flash device electrically connected to the camera body) and at least one sub-flash device (e.g., a slave flash unit) which is wireless controlled by the main flash device, wherein the main flash device emits a flash emission serving as a command signal to transmit the command signal to the sub-flash device to control a discharging operation of the sub-flash device, are known in the art. In such conventional flash photography systems, since the main flash device is activated to emit one or more low flash emissions to transmit the command signal to the sub-flash device, the power consumption in the command signal transmitting operation becomes greater as the number of transmissions of the command signals increases.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a flash photography system which makes it possible to control flash emissions with a high degree of energy efficiency in a multiple flash photography using a plurality of wireless-controlled flash devices.
To achieve the object mentioned above, according to an aspect of the present invention, a flash photography system having a camera body, a main flash device and at least one sub-flash device, wherein the main flash device emits at least one low flash emission serving as a main-flash emission command signal to transmit the main-flash emission command signal to the at least one sub-flash device, the at least one sub-flash device emitting a flash emission in accordance with the main-flash emission command signal. The flash photography system includes a designating device for designating a flash emission mode of a main-flash emission, and a command device which activates the main flash device to emit the at least one low flash emission serving as the main-flash emission command signal to transmit the main-flash emission command signal to the at least one sub-flash device in a manner corresponding to the designated flash emission mode.
In an embodiment, the main flash device is a built-in flash of the camera body.
In an embodiment, the main flash device is an external flash device which is electrically connected to the camera body.
In an embodiment, the sub-flash device includes a slave flash unit which is controlled by the main flash device by wireless control.
In an embodiment, the designating device and the command device are incorporated in the main flash device.
In an embodiment, the designating device and the command device are incorporated in the camera body.
Preferably, the flash emission mode includes a uniform flash emission mode in which the at least one sub-flash device is driven to emit a rapid series of short flash pulses to thereby emit the main flash emission with a substantially uniform intensity for a given period of time. If the uniform flash emission mode is designated by the designating device, the command device activates the main flash device to emit at least two low flash emissions successively serving as the main-flash emission command signal. A time interval between two low flash emissions of the at least two low flash emissions designates a duration of time of the main flash emission in the uniform flash emission mode.
In an embodiment, the flash emission mode includes a normal flash mode in which the at least one sub-flash device is driven to emit a single flash emission to thereby emit the main flash emission; wherein the command device activates the main flash device to emit a single low flash emission serving as the main-flash emission command signal in the case where the normal flash mode is designated by the designating device.
Preferably, the command device activates the main flash device to transmit the main-flash emission command signal to the at least one sub-flash device after activating the main flash device to emit another at least one low flash emission to transmit another command signal, corresponding to the flash emission mode designated by the designating device, to the at least one sub-flash device. Each sub-flash device includes a receiver which receives signals which are transmitted from the command device; a setting device which sets a flash emission mode corresponding the another command signal received by the receiver; and a controller which activates the at least one sub-flash device to emit the main flash emission in the flash emission mode set by the setting device upon the receiver receiving the main-flash emission command signal which corresponds to the flash emission mode set by the setting device.
In an embodiment, the command device activates the main flash device to transmit the pre-flash emission command signal, a light-magnification command signal, and the main-flash emission command signal to the at least one sub-flash device successively in that order to control a flash emission of the at least one sub-flash device. The pre-flash emission command signal commands the at least one sub-flash device to start emitting a preliminary flash emission before the main flash emission. The light-magnification command signal specifies a light amount of the main flash emission of the at least one sub-flash device.
Preferably, the pre-flash emission command signal includes the another command signal.
In an embodiment, the main flash device includes a first CPU which can have data communication with a second CPU provided in the camera body, the first CPU serving as the command device.
In another embodiment, the camera body includes a first CPU which can have data communication with a second CPU provided in the main flash device, the first CPU serving as the command device.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2000-284413 (filed on Sep. 19, 2000) and No.2001-34583 (filed on Feb. 9, 2001), which is expressly incorporated herein by reference in its entirety.
REFERENCES:
patent: 5721971 (1998-02-01), Sasaki
patent: 6088542 (2000-07-01), Yanai et al.
patent: 6404987 (2002-06-01), Fukui
patent: 11119283 (1999-04-01), None
Iwamoto Shigeru
Kawasaki Masahiro
Ohkura Tadahisa
Sato Osamu
Taneoka Kazuhito
Greenblum & Bernstein P.L.C.
PENTAX Corporation
Smith Arthur A
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