JPH067242B2 - Zoom strobe irradiation angle variable device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom strobe in which the irradiation angle of the strobe changes according to zooming of the zoom lens.

[Conventional technology]

In the conventional compact camera, the flash discharge tube was moved in the irradiation direction between the reflector and the diffusion plate in conjunction with the zooming of the taking lens so that the irradiation angle was widened in the wide-angle range and narrowed in the telephoto range. . In order to move the flash discharge tube as described above, a moving mechanism such as a motor and a flat cam driven by the motor is used. There is also a strobe device for a single-lens reflex camera that automatically adjusts the irradiation angle by moving a panel such as a diffusion plate in front of the flash discharge tube with a motor based on the focal length information from the lens. Has been.

[Problems to be solved by the invention]

Since this conventional zoom strobe device drives a panel such as a flash discharge tube or a diffusion plate by a motor, a mechanical interlocking mechanism is required in addition to the motor and a circuit for driving the panel, and the structure is It has the drawback of becoming complicated and prone to failure, and of being large and heavy.

The present invention has been made in order to solve such a drawback, and provides a strobe irradiation angle varying device capable of obtaining an irradiation angle according to zooming of a photographing lens without using a mechanical interlocking mechanism. The purpose is to

[Means for solving problems]

In order to achieve the above object, the present invention is a light emitting unit in which a plurality of flash discharge tubes are arranged along the irradiation direction of illumination light, and a zoom ratio detecting unit for detecting the zoom ratio of a photographing lens,
It comprises a light emission control means for receiving the signal output from the zoom ratio detection means and controlling the operation of the plurality of flash discharge tubes in accordance with the zoom ratio.

[Action]

According to the above configuration, the plurality of flash discharge tubes arranged along the irradiation direction of the illumination light are selected by the light emission control means, or they are emitted at a predetermined light emission ratio. The subject is illuminated with an irradiation angle according to the ratio.

〔Example〕

In FIG. 1 showing an example of a compact camera using the present invention, a taking lens 2 is fixed to the front surface of a camera body 1 at a substantially central portion thereof, and a finder 3 and a stroboscopic irradiation surface 4a are arranged on an upper portion thereof. A shutter button 5 is provided on the camera body 1. The taking lens 2 is composed of a zoom lens, and the focal length of the taking lens 2 can be changed between a telephoto range and a wide-angle range by operating a seesaw switch 6 provided on the front surface of the camera body 1. it can.

FIG. 2 shows the structure of the zoom strobe unit.
The stroboscopic light emitting section 4 includes a reflector 7, a Fresnel plate 8 and 2
It is composed of a book flash discharge tube 10a, 10b.
A feature of the present invention is that the flash discharge tubes 10a and 10b are arranged in parallel in the flash light irradiation direction. The flash light from the flash discharge tubes 10a and 10b illuminates the subject through the reflector 7 and directly through the Fresnel plate 8.
When the flash discharge tube 10a closer to the Fresnel plate 8 emits light, the light is irradiated on the short-distance subject at a large irradiation angle. On the contrary, if the flash discharge tube 10b farther from the Fresnel plate 8 emits light, the light is emitted. Even a long-distance subject is illuminated with a small illumination angle. The flash discharge tube 10 will be described in detail later.
Even when a or 10b is selected or light is emitted at the same time, the light emission control is performed so that the total guide number becomes constant.

FIG. 3 shows a circuit configuration for controlling the light emission of the two flash discharge tubes 10a and 10b. When the seesaw switch 6 is operated to perform the zooming of the taking lens 2, the zoom control circuit 12 operates via the sequence control circuit 11. As a result, the motor 13 is driven and the variable power lens 14 in the taking lens 2 moves in the optical axis direction for zooming. The rotation position of the motor 13 is, for example, a zoom ratio detection unit 1 including a potentiometer.
5, and the detection signal is sent to the time determination circuit 16. The time determination circuit 16 produces a signal that determines the light emission time of each of the flash discharge tubes 10a and 10b according to the detection signal from the zoom ratio detection circuit 15. That is, when the zoom ratio belongs to the telephoto range, the flash discharge tube 10
A signal that gives a short light emission time to a and a relatively long light emission time to the flash discharge tube 10b is sent.

The gate control circuit 17 is connected to the flash discharge tubes 10a and 10b in series according to the light emission time control signal.
TO (gate turn-off switch) 18a, 18b
The ON and OFF signals are output to the respective gate terminals of.
The GTO is an element considered to have a cutoff function in the thyristor, and has the ability to open and close the main current with a particularly small gate power.
Gate turn-on and gate turn-off can be performed by the N and OFF signals to control the light emission of the flash discharge tubes 10a and 10b.

The DC-DC converter 23 is the power switch 20 of the camera.
It operates by a signal from the sequence control circuit 11 at a predetermined time such as when the film is turned on or when the film winding is completed, and converts the voltage of the lithium battery 19 into a high voltage, so that the unidirectional current through the diode 22 is supplied to the main capacitor 24. Send it out and charge it. In addition, double throw type synchro switches 25a and 25b are provided to give a trigger of light emission to the flash discharge tubes 10a and 10b, and these are turned on when the shutter is operated. Synchro switch 25
When a and 25b are turned on, high voltage conversion transformers 21a and 2
A high voltage is generated on the secondary side of each of the 1b, and the flash discharge tube 10
It becomes a trigger signal of a and 10b.

With the above configuration, it is possible to control the wide-angle range, the telephoto range, and the light emission amounts of the flash discharge tubes 10a and 10b between them as shown in FIG. When the photographing lens 2 is zoomed and, for example, the variable magnification lens 14 is moved to the widest angle side, a signal from the zoom ratio detector 15 causes the time constant circuit 16 to operate, and the time constant circuit 16 includes only the gate of the GTO 18a. Is set to be kept in the ON state for a certain time (maximum time). When the shutter button 5 is pressed to operate the shutter, the trigger switches 25a and 25b are turned on in synchronization with the operation of the shutter, and at the same time, the sequence control circuit 11 supplies an operation signal to the time determination circuit 16.

Since the gate control circuit 17 holds only the gate of the GTO 18a in the ON state for a certain time by supplying the operation signal to the time setting circuit 16, only the flash discharge tube 10a close to the Fresnel plate 8 is connected to the main capacitor 24. Light is emitted by the stored electric charge, and this light emission is stopped after a fixed time set by the time determination circuit 16. Therefore, the flash discharge tube 10b far from the Fresnel plate 8 does not emit light, and as shown by the solid line in FIG. 2, the subject is illuminated with the illumination light of the maximum irradiation angle having the light distribution suitable for wide-angle shooting. . Since the aperture diameter or the maximum aperture diameter of the program shutter at this time is determined according to the subject distance, stroboscopic photography with proper exposure is performed.

Further, when the taking lens 2 is set to the zoom ratio closest to the telephoto side, the time-setting circuit 16 causes the gate control circuit 17 to operate only the flash discharge tube 10b farther from the Fresnel plate 8 by 100%. Therefore, the gate of the GTO 18b is turned on. Therefore, when the shutter button 5 is pressed to take an image, as shown by a broken line in FIG. 2, the light emitting unit 4 is illuminated with the minimum irradiation angle by this camera suitable for telephoto.

When the zoom ratio is set in the intermediate range between the wide angle and the telephoto, the time setting circuit 16 receives the operation signal and then turns on both the GTOs 18a and 18b through the gate control circuit 17 for the same time. Works. The light emission time due to this is shorter than the light emission time when either one emits light as described above, and the total light emission amount is set to be the same as when one emits full light. As a result,
When the shutter operates under a diaphragm aperture corresponding to the subject distance, both the flash discharge tubes 10a and 10b are discharged and the subject is illuminated with a light distribution suitable for the zoom ratio in the intermediate range.

Further, when the taking lens 2 is set to a zoom ratio other than the above, the sharing of the light emission of the flash discharge tubes 10a and 10b is set by the time setting circuit 16 as shown in FIG. That is, in the case of the zoom ratio on the wide-angle side of the intermediate range, each GTO 18 has a large light emission amount from the flash discharge tube 10a and a small light emission amount from the flash discharge tube 10b.
The turn-off times of a and 18b are set.
Therefore, it is possible to illuminate the subject with a light distribution suitable for any zoom ratio. Note that substantially the same effect can be obtained by simply setting the light emission ratios of the flash discharge tubes 10a and 10b stepwise according to the zoom ratio. Further, it goes without saying that the present invention can also be used for an auto strobe.

FIG. 5 shows an example in which two pairs of electrodes are provided in a single tube instead of arranging two flash discharge tubes in parallel. If the flash discharge tubes 30 configured as described above are arranged such that the respective electrodes are arranged in parallel along the light irradiation direction, the same operation can be obtained using the circuit shown in FIG. .

〔The invention's effect〕

As described above, according to the present invention, it is possible to change the irradiation angle of the strobe in conjunction with zooming of the lens without using mechanical interlocking of the motor. Noise during stroboscopic zooming can be eliminated.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a camera using the present invention. FIG. 2 is a sectional view showing an example of a stroboscopic light emitting section used in the present invention. FIG. 3 is a block diagram showing an embodiment of the present invention. FIG. 4 is a diagram showing the light emission amounts of the flash discharge tubes 10a and 10b in the wide angle range, the telephoto range, and the range therebetween. FIG. 5 is a sectional view showing another example of the stroboscopic light emitting section. 4 ... Strobe light emitting part 6 ... Seesaw switch 7 ... Reflector 8 ... Fresnel plate 10a, 10b ... Flash discharge tube 30 ... Flash discharge tube

Claims (1)

[Claims] 1. A zoom strobe in which an irradiation angle of a strobe is variable in accordance with zooming of a zoom lens, and a plurality of flash discharge tubes arranged in parallel between a reflector and a diffusion plate along an irradiation direction of illumination light. A means for detecting the zoom ratio of the photographing lens, and a light emission control means for controlling the light emission amount of each of the plurality of flash discharge tubes in accordance with the zoom ratio detected by the zoom ratio detection means,
A device for varying the irradiation angle of a zoom strobe, characterized in that the emission ratio of each flash discharge tube is continuously changed according to the zoom ratio of the taking lens.