JPH0438336Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a strobe that can be attached to the outside of a variable-focus camera that can take pictures at at least two different focal lengths.

[Conventional technology]

Among lens shutter type compact cameras, cameras with zoom lenses that can continuously change the focal length from, for example, wide-angle photography (wide-angle photography) with a focal length of about 35 mm to telephoto photography (telephotography) with a focal length of about 70 mm are known. In the zoom lens of such a camera, the brightness of the photographing lens is usually darker on the telephoto side than on the wide side.
Therefore, even if such a camera is equipped with a small auto-adjustable strobe to enable shooting indoors, if the flash is set to the same flash control standard as when shooting wide-angle shots, the exposure will be poor. There will be a shortage. Furthermore, because conventional built-in strobes must be housed in a small and lightweight camera body, most of them are small strobes with a guide number (GN) of around 10. Therefore, apart from wide-angle shooting, during telephoto shooting where the subject distance tends to be long, the absolute amount of light emitted by the built-in strobe tends to be insufficient, making it difficult to properly control the flash. In order to eliminate this problem, a method has been adopted in which, in addition to the built-in strobe, an external strobe is synchronously emitted to increase the amount of illumination light.

By the way, compact cameras with built-in strobes generally do not have hot flash or synchronization contacts for external strobes, so for the reasons mentioned above, when using an external strobe, it is important to It is necessary to use a slave type strobe that emits light in synchronization.

However, as mentioned above, when the focal length of the photographic lens is changed and the brightness of the photographic lens changes accordingly, unless information about the F number of the photographic lens is provided from the camera side to the slave type strobe. A slave type strobe cannot be adjusted properly. Therefore, in order to make it possible to apply a slave strobe to a variable-focus camera, it is necessary to extract focal length information from the camera and input it to the slave strobe as an electrical signal, or to adjust the slave strobe. You need to be able to manually adjust the light level and be able to adjust this to match the focal length.

[Problem that the invention attempts to solve]

However, even though it is a variable focal length type, it is difficult for camera manufacturers to provide circuit elements and contacts that electrically detect the focal length and output it to a slave strobe in a popular compact camera. This results in a significant increase in cost, and at the same time, the slave type strobe also requires corresponding circuit elements, contacts, etc., which increases the cost burden on the strobe side. Further, if a slave type strobe is provided with a manual operation section for adjusting the light control level, the manual operation becomes extremely complicated and impractical when the photographic lens is a zoom lens.

[Purpose of invention]

The present invention has been developed in view of the above-mentioned conventional technology, and does not require any electrical connection to the camera, and when the focal length of the photographic lens is changed, it can be adjusted accordingly. An object of the present invention is to provide an external strobe for a variable focus camera whose light control level is automatically adjusted.

[Means for solving problems]

In order to achieve the above object, the present invention includes a detection means for detecting light emission from a built-in strobe that is moved according to a change in focal length, and a discharge tube that starts emitting light in response to a detection signal from the detection means. A light emission stop means receives reflected light from a subject illuminated by light emission from the discharge tube, and outputs a light emission stop signal to stop light emission from the discharge tube based on the amount of light received; and movement of the built-in strobe. and an adjusting means for controlling the light emission stopping means in conjunction with the light emitting device, so that the amount of light emitted from the discharge tube is determined by both the focal length of the photographing lens and the amount of light received.

[Effect]

For cameras that move the built-in strobe in conjunction with changing the focal length of the shooting lens,
When the external strobe of this invention is attached, the autoflash level is automatically adjusted in conjunction with the amount of movement of the built-in strobe to cope with the fact that the photographing lens becomes dark on the telephoto side, ensuring proper exposure at all times. You will be able to take pictures of

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

〔Example〕

A first embodiment of the present invention will be described. In FIGS. 1 and 2 showing a state in which the external strobe 1 of the present invention is attached to a camera 30 equipped with a zoom lens 31, the camera 30 is
A ring 32 for zooming is provided on the outer periphery of the lens barrel, and by rotating this ring 32, it is possible to zoom from the wide side to the telephoto side. The camera 30 also has a small built-in strobe 33 that automatically fires and adjusts light.
This built-in strobe 33 moves in conjunction with the rotation of the ring 32, from the retracted position at the widest side (Fig. 1) to the raised position at the most telephoto side (Fig. 2). Light distribution characteristics are gradually changing.

The reason why the built-in strobe is raised as the zoom lens 31 is zoomed toward the telephoto side is that during telephoto shooting, the photographing optical axis and the strobe illumination optical axis become nearly parallel, and when photographing a person,
This is because the so-called "red eye phenomenon" is likely to occur.

The main body 2 of the external strobe 1 is made of plastic, and is fixed to the side surface of the camera 30 with screws 3. A transparent cover 4 is attached to the upper front surface of the main body 2 to protect the discharge tube (not shown) and to flatten the light distribution characteristics. A box-shaped member 5 is movably attached below the cover 4 and moves up and down guided by guides 6 and 7 provided on the inner wall of the main body 2. A spring 8 is attached above this box-shaped member 5, and this spring 8 causes the box-shaped member 5 to
is always in contact with the upper part of the built-in strobe 33. Due to the action of the spring 8, the box-shaped member 5 allows the zoom lens 31 to fall downward on the wide-angle side as shown in FIG. Move to.

The box-shaped member 5 includes a filter 9 in which a chevron-shaped opaque portion as shown in the figure is arranged on a transparent base such as acrylic, so that the light transmittance gradually changes from one end to the other. is attached, and moves up and down as the box-shaped member 5 moves up and down. An opening 2a is formed in the main body 2 in front of the filter 9, and a silicon photo diode (SPD) 10 as a light receiving element for dimming is arranged at the rear.
When the transparent base surface of the filter 9 is placed in front of this SPD 10 as shown in FIG.
When the amount of light that reaches 0 increases and the mountain-shaped opaque part is placed as shown in Figure 2, the amount of light that reaches SPD 10 decreases, causing the dimming level of external strobe 1 to match the amount of movement of the built-in strobe. adjusted accordingly.
Further, a photo transistor 11 as a slave light receiving element is attached above the opening 2a, and detects light emission from the built-in strobe 33 to cause the external strobe 1 to emit light. A neon lamp 45 (see FIG. 5) is attached to the back of the main body 2 to notify when charging of the external strobe 1 is complete.

In FIG. 5, which shows a circuit used in the external strobe 1, a battery 40, a switch 41, and a booster circuit 42 are connected in series. The voltage of the battery 40 is boosted to high-voltage alternating current by a booster circuit 42, rectified by a diode 49, and then supplied to a trigger capacitor 50, a neon lamp 45, and a main capacitor 51. The primary winding 52a of the trigger transformer 52 is connected to the trigger capacitor 50.
and a phototransistor 11 are connected in series. The discharge tube 54 is connected in parallel to the main capacitor 51 and its trigger electrode 54
a is connected to the secondary winding 52b of the trigger transformer 52.

Further, a thyristor 55 is connected to the discharge tube 54, and the output terminal of the operational amplifier 44 is connected to the gate terminal of the thyristor 55. The switch 4 is connected to the inverting input terminal of the operational amplifier 44.
1 is connected, a capacitor 56 and SPD10 are connected to the non-inverting input terminal, and this
SPD 10 is connected to switch 41.

The operation of the external strobe 1 of the present invention will be explained. When the external strobe 1 is attached to the side of the camera 30 via the screw 3, the box-shaped member 5 on the wide side
is lowered by a spring 8 as shown in FIG. 1, and the transparent part of the filter 9 attached to the box-shaped member 5 is placed in front of the SPD 10. Also,
As the lens barrel 32 of the camera 30 is rotated and zoomed toward the telephoto side, the built-in strobe 33 is raised and the box-shaped member 5 is pushed up.
As a result, the filter 9 also moves upward, and the mountain-shaped opaque portion disposed in front of the SPD 10 increases.

Turn on switch 41 for charging external strobe 1
Then, a high voltage alternating current is generated at the output terminal of the booster circuit 42. This alternating current is rectified by a diode 49 and then supplied to the neon lamp 45, trigger capacitor 50, and main capacitor 51.
Trigger capacitor 50 and main capacitor 51
When the battery is charged, the neon lamp 45 is turned on.
When the camera's release button 34 (shown in FIG. 1) is operated, the shutter is operated, and in synchronization with this, the built-in strobe 33 emits light. The photo transistor 11 detects this light emission and starts discharging the trigger capacitor 50. The voltage of the trigger capacitor 50 is boosted by the trigger transformer 52 and then applied to the trigger electrode 54a of the discharge tube 54. As a result, the discharge tube 54 starts discharging, receives the electrical energy of the main capacitor 51, and emits light instantaneously.

When the SPD 10 receives the reflected light from the flash emitted by the discharge tube 54, this
The electrical signal generated by SPD10 is connected to capacitor 5
6, and when a certain amount accumulates, the operational amplifier 44
A differential input voltage is produced between the two input terminals of the operational amplifier 44, and an output voltage is produced at the output terminal of the operational amplifier 44. Since this output voltage is applied to the gate terminal of the thyristor 55, the electrical energy of the main capacitor 51 that was flowing to the discharge tube 54 when the thyristor 55 is turned on is bypassed and no longer flows to the discharge tube 54.
Light emission from the discharge tube 54 is stopped.

The flash time of the discharge tube 54 is determined according to the amount of light incident on the SPD 10, and on the wide side in FIG. 1, the transparent part of the filter 9 is placed between the SPD 10 and the opening 2a as described above. Because there are
The discharge tube 5 stops emitting light from the discharge tube 54 in a short period of time.
The amount of light emitted by the discharge tube 54 decreases, and as you zoom toward the telephoto side, a portion of the filter 9 with lower transmittance is located, so the time required to stop the discharge tube 54 from emitting light becomes shorter than when zooming to the wide-angle side. It takes a long time, and the amount of light emitted from the discharge tube 54 reaches the second level.
It is most common in the state shown in the figure. Of course, at each focal length from the wide side to the telephoto side, automatic light control is performed at each level, that is, light control is performed according to the reflectance of the subject and the brightness of the room.

3 and 4 show a state in which an external strobe 70 according to a second embodiment of the present invention is attached to the side surface of the camera 30 with a screw 74. The external strobe 70 is
It is composed of a main body 71 and a base 72 molded from opaque plastic, and the main body 71 is slidably attached to the base 72. The outer surface of the main body 71 is provided with a light emitting section 75, a photo diode 11 as a slave light receiving element, and an opening 71a, and inside is an SPD 1 exactly the same as in the first embodiment.
0 and other automatic light control devices, strobe charging devices, etc. are housed there. In addition, the base 72 has a protruding piece 7.
3 is integrally molded with the base 72, and this projecting piece 73 is provided with an opening 73a with a small upper part and a large lower part as shown in the figure.
It is placed between the SPD10.

On the wide side shown in FIG. 3, the lower part of the opening 73a is located between the opening 71a and the SPD 10, so
The amount of light incident on the SPD 10 increases, and the amount of light emitted by the external strobe 70 is adjusted to a low level.
Further, the zoom lens 31 is zoomed to the tele side, and in the most tele side state shown in FIG. 4, the built-in strobe 33 of the camera 30 rises and
is pushed up, and the upper part of the opening 73a is connected to the opening 71a.
Since it will be located between SPD10,
The amount of light incident on the SPD 10 decreases, and the amount of light emitted by the external strobe 70 is adjusted to a high level. Furthermore, at this time, since the position of the light emitting section 75 becomes higher, the light distribution characteristics are also changed, making it more difficult for the "red eye phenomenon" to occur. Of course, in the state between FIG. 3 and FIG. 4, the intermediate portion of the opening 73a is disposed between the opening 71a and the SPD 10,
At this time, automatic light adjustment is performed at a level corresponding to the brightness of the zoom lens 31 at this time.

The above description has been about the case where the external strobe 1 of the present invention is attached to a camera with a zoom lens, but it is possible to select only the two focal points of wide and telephoto, and the two focal points are equipped with a built-in strobe that pops up in conjunction with this. It can also be attached to a camera in the same way.

[Effect of idea]

As explained above, when the strobe of the present invention is attached to a compact camera that can select at least two focal lengths for shooting and is equipped with a small built-in strobe, it impedes the ease and portability of shooting, which are the characteristics of compact cameras. It allows you to take pictures with sufficient light intensity while supplementing the light intensity of the built-in small flash without having to do anything, and it also automatically changes the light control standards in conjunction with the amount of movement of the built-in flash.
You will be able to always take photos with the correct exposure from the wide side to the telephoto side.

[Brief explanation of the drawing]

FIG. 1 is an external view showing the first embodiment of the present invention attached to a camera during wide shooting. FIG. 2 is an external view showing the first embodiment of the present invention attached to a camera during telephotography. FIG. 3 is an external view showing the second embodiment of the present invention attached to a camera during wide shooting. FIG. 4 is an external view showing the second embodiment of the present invention attached to a camera during telephotography. FIG. 5 is a circuit diagram of an embodiment of the present invention. 1,70...External strobe, 2,71...Main body, 2a, 71a, 73a...Opening, 5...Box-like member, 8...Spring, 9...Filter, 10...
SPD, 11...Photo transistor, 51...
...Main capacitor, 54...Discharge tube.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In an external strobe attached to a camera that moves the built-in strobe in conjunction with changing the focal length of the photographic lens, detection for detecting light emission from the built-in strobe. means, a discharge tube that starts emitting light in response to a detection signal from the detection means, and a discharge tube that receives reflected light from a subject illuminated by the light emission of the discharge tube, and detects the discharge tube based on the amount of light received. a light emission stop means for outputting a light emission stop signal to stop the light emission;
and an adjusting means for adjusting the amount of light received by the light emitting stop means in conjunction with the movement of the built-in strobe, so that the amount of light emitted from the discharge tube corresponds to the aperture diameter of the photographing lens, which changes as the focal length of the photographing lens changes. An external strobe for a variable focus camera, characterized in that it can be adjusted by (2) The variable focus according to claim 1, wherein the adjustment means is a filter that is inserted into and taken out of the light receiving optical axis of the light emission stop means in conjunction with the movement of the built-in strobe. External flash for camera. (3) A utility model registration characterized in that the adjustment means is a plate-shaped member having a wedge-shaped opening that is moved in and out of the light receiving optical axis of the light emission stop means in conjunction with the movement of the built-in strobe. An external strobe for a variable focus camera according to claim 1.