JPS6214819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auto-flash switching device for a camera that switches from auto photography to flash photography in conjunction with a power switch of the flash device.

In a camera having an automatic exposure control device, the exposure time is automatically controlled based on exposure information such as subject brightness incident on a light receiving element and an aperture value. In the case of flash photography, photography is performed at a fixed shutter speed, for example, 1/40 to 1/45, in order to synchronize with the shutter and in relation to the amount of light. For this reason, a resistor for flash photography is provided in parallel with the light receiving element, and can be selectively switched by an auto flash changeover switch to perform automatic photography and flash photography.

In conventional cameras, a claw for operating the auto-flash selector switch is provided at the bottom of the accessory shoe and protrudes upward, and when the flash device is attached to the accessory shoe, the claw is attached to the foot of the flash device. The auto-flash switching switch protrudes into a recess provided in the light-receiving element and switches from the light-receiving element side to the fixed resistance side to perform flash photography. In cases other than flash photography, a cover for protecting the X contact terminal is attached to the accessory shoe, and the claw is held in a downwardly pressed state by this cover to perform automatic photography.

This device detects the attachment of the flash device and mechanically switches the auto-flash switching switch, so if the cover is not fully attached, the claw protrudes upward and switches to flash photography. The disadvantage is that the image becomes distorted and proper exposure cannot be obtained. Furthermore, since the switching claw is provided on the accessory shoe, there is also the drawback that the flashing device cannot be installed smoothly.

SUMMARY OF THE INVENTION In view of the above drawbacks, it is an object of the present invention to provide an auto/flash automatic switching device that can reliably switch between flash photography and auto photography.

Another object of the present invention is to provide an auto-flash switching device that allows the flash device to be installed smoothly.

In the device of the present invention, when the flash device is attached to the accessory shoe, a magnetic coil is installed inside the camera that is electrically connected to the flash device, and the power switch is turned on to charge the flash capacitor. When the magnet coil is energized, the magnetic force of the coil automatically switches the auto/flash switching switch from the light receiving element side for auto photography to the resistor side for flash photography. It is something to do. The power switch of the flash device is always turned on during flash photography, so by linking it to the auto flash changeover switch, it is possible to prevent malfunctions caused by improperly attaching the cover, etc. Further, since a detecting member such as a claw for operating the auto-flush changeover switch is not required, the flash device can be installed smoothly. Furthermore, it is convenient because automatic photography can be performed while the flash device is attached by turning off the power to the flash device. Also, since this magnet coil is connected in parallel with the main capacitor of the flash device, no current flows through the magnet while the flash device is insufficiently charged (while charging), so the selector switch is set to the auto position. switch to the flash position only after charging is complete.
Therefore, even if you press the shutter while the battery is insufficiently charged, you can still shoot automatically, so you won't waste any film.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention.
The flash circuit 10 includes a power source 11, a power switch 12,
and a capacitor 13 are connected in series, and when the power switch 12 is turned on, the capacitor 13 is charged and stores energy that causes the discharge tube 14 to instantaneously emit light.
A series circuit of resistors 15 and 16 is connected in parallel with the capacitor 13. In parallel with this resistor 15,
A circuit in which the trigger capacitor 17 and the primary coil 18 of the booster are connected in series is connected.
This trigger capacitor 17 and primary coil 18
An X contact 21 is connected in parallel to the X contact terminals 19 and 20, and when the X contact 21 is turned on, the trigger capacitor 17 is discharged. A secondary coil 22 is provided corresponding to the primary coil 18, and the high voltage induced in the secondary coil 22 causes the discharge tube 14 to
A flash of light begins.

Terminals 23, 2 are connected in parallel with the capacitor 13.
A magnet coil 25 is connected through the capacitor 4, and is energized when the capacitor 13 is charged to a predetermined level to automatically switch from auto photography to flash photography.

One of the X contact terminals 19 and 20 is normally grounded. Therefore, Figures 2 and 3
As shown in the figure, a terminal 19a constituting the other terminal, e.g.
(Fig. 3), and when the leg portion 27 of the flashing device 28 is attached to the accessory shoe 26, these X contact terminals 19a, 1
9b is now connected. Terminals 23a and 24b constituting terminals 23 and 24 are provided on the accessory shoe 26, respectively, and are connected to terminals 23a and 24b on the flash device 28 side provided on the lower surface of the leg portion 29, respectively. There is.

The X contact 21 and the magnetic coil 25 are
The other circuit devices are installed in the flash device 28, which is provided within the camera.

The automatic exposure control device 29 has a resistor 30 for flash photography and a light receiving element 31 for automatic photography, one of these and a capacitor 32 constitute a time constant circuit, and when a trigger switch 33 is opened. When the capacitor 32 is charged to a predetermined level, the switching circuit 34 is reversed to cut off the magnet coil 35 and close the shutter. The resistor 30 and the light receiving element 31 are switched by an auto flash changeover switch 36. Auto flash selector switch 3
6 to the resistor 30 side, the flash synchronization speed is obtained and flash photography is performed. Furthermore, when the auto flash changeover switch 36 is switched to the light receiving element 31 side, the capacitor 32 is charged in accordance with the brightness of the subject and automatic photographing is performed.

This auto flash changeover switch 36 is
It is designed to be switched by the magnet coil 25. That is, power switch 1
When 2 is turned ON, the magnet coil 25 is excited and the auto flash changeover switch 36 is switched from the light receiving element 31 side to the resistor 30 side, thereby switching from auto photography to flash photography. A power supply 37 is provided to operate these circuits, and a switch 38
Power is supplied via.

Next, the operation of the device of the present invention having the above configuration will be explained. If the leg part 27 of the flash device 28 is attached to the accessory shoe 26, the leg part 27
Terminals 19b, 23b, 24b provided at the bottom of the accessory shoe 26, and terminals 19a, 2 provided at the bottom of the accessory shoe 26.
3a and 24a are electrically connected to each other.

Flash device 28 prior to flash photography
When the power switch 12 is turned on, the capacitor 13 is charged. When the capacitor 13 is charged, the magnet coil 25 connected in parallel with the capacitor 13 is energized, and the auto flash changeover switch 36 is switched from the light receiving element 31 side to the resistor 30 side. When the release button is pressed, the shutter is opened, and in conjunction with this, the trigger switch 33 is opened, and the X contact 2
1 is closed.

When the X contact 21 is closed, the trigger capacitor 17 is discharged, and the discharge current flows into the primary coil 18, inducing a high voltage in the secondary coil 22. This high voltage causes the discharge tube 14 to emit light.

Further, when the trigger switch 33 is opened, the capacitor 32 is charged according to the time constant of the resistor 30 and the capacitor 32. When the capacitor 32 reaches a predetermined level, the switching circuit 34 is reversed to demagnetize the magnet coil 35 and close the shutter after the discharge tube 14 has emitted light.

Note that if photography is mistakenly performed before the capacitor 13 is fully charged, automatic photography will be performed. That is, since a predetermined current does not flow through the magnet coil 25 while the capacitor 13 is being charged, the auto flash changeover switch 36 remains connected to the light receiving element 31 side. Automatic exposure control is therefore performed.

The flash device 28 is attached to the accessory shoe 26.
If you want to take an outdoor photo with the camera attached, just turn off the power switch 12. When the power switch 12 is turned off, the auto flash changeover switch 36 is switched to the light receiving element 31 side, and the capacitor 32 is charged according to the amount of light incident on the light receiving element 31, so that automatic photography can be performed. When the flash device 28 is removed from the accessory show 26, the magnet coil 25 is disconnected from the flash circuit 10. As a result, the auto flash changeover switch 36
The camera will switch to the side and auto shooting will take place.

According to the device of the present invention having the above-mentioned configuration, the auto flash changeover switch is switched in conjunction with the power switch of the flash device, so it always accurately switches from auto shooting to flash shooting automatically without causing any malfunction. You can switch to . Further, since there is no mechanical detection member such as a claw for detecting attachment of the flash device and switching to flash photography, the attachment of the flash device can be carried out smoothly. Furthermore, if the flash device is turned off, automatic photography can be performed while the flash device is attached, which is convenient when taking indoor and outdoor photos alternately.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a perspective view of an accessory shoe, and FIG. 3 is a perspective view of a flash device. 10... Flash circuit, 12... Power switch, 13...
Capacitor, 14...Discharge tube, 19,20...X contact terminal, 23,24...Terminal, 25...Magnetic coil, 26...Accessory shoe, 28...Flash device, 29...Automatic exposure control device, 30...Flash photography 31... Light receiving element for automatic shooting, 34... Switching circuit, 35... Magnetic coil for shutter closing.

Claims (1)

[Scope of Claims] 1. It has a light-receiving element for automatic photography and a resistor for flash photography, and can perform automatic photography and flash photography by selectively switching the light-receiving element and the resistor with a changeover switch. In such a camera, a magnetic coil is provided inside the camera, which is connected in parallel with the capacitor of the flash device when the flash device is installed, and is activated by the power switch.
The auto camera is characterized in that the changeover switch is switched depending on whether charging of the capacitor is completed or not, and automatic shooting is switched from automatic shooting to flash shooting when charging of the capacitor is completed.
Flash automatic switching device. 2. A terminal connected to the magnetic coil is provided exposed at the bottom of the accessory shoe, and a terminal connected in series to the power supply of the flashing device via a power switch is provided at the bottom of the accessory shoe, and the flashing device is connected to the flashing device. 2. The auto-flash automatic switching device according to claim 1, wherein both terminals are connected when the accessory shoe is attached to the accessory shoe.