JPH10260507A - Film unit with lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically switch a diaphragm in accordance with subject luminance by providing a diaphragm switching means for switching a diaphragm value according to the level of the subject luminance detected by a photometric circuit. SOLUTION: This film unit is provided with a transistor Tr5 whose collector is connected to a shape memory element 21 and whose base is connected between a Cds 14 and a resistance R2. As for the action of the transistor Tr5; the transistor Tr5 is actuated when the Cds detects that the subject luminance is higher than specified luminance, and it is not actuated when the Cds 14 detects that the subject luminance is lower than the specified one. Since the element 21 is energized when the luminance is high, it self-generates heat by specific resistance and is deformed to shape held at high temperature because of temperature rising caused by generated heat. Since the element 21 is not energized when the luminance is low, it keeps the shape held at normal temperature. Thus, the diaphragm is switched by the change of the shape of the element 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film unit with a lens capable of automatically switching the aperture by detecting the brightness of a subject.

[0002]

2. Description of the Related Art When photographing using a film unit with a lens, if the subject brightness is high outdoors, a small aperture may be used. However, since the subject brightness is low outdoors in the shade of a tree or in the morning and evening, or indoors, the subject brightness is low. It is desirable to be able to set a larger aperture. Also, when the subject brightness is high, the strobe is unnecessary, but when the subject brightness is low, it is clearer to use the strobe to make the picture clearer.
If the aperture can be switched to a larger aperture, the shooting distance of the strobe will be extended.

From such a viewpoint, there is known a configuration in which the aperture is switched in conjunction with an operation of turning on / off a power switch of a strobe manually at the discretion of a photographer.

Japanese Patent Laid-Open Publication No. Hei 7-218993 discloses an automatic flash which emits a flash automatically in accordance with the luminance of a subject with a simple structure without using a microcomputer.

[0005]

As described above, even if the film unit with a lens can be switched between a large aperture and a small aperture as described above, it is difficult for the photographer to judge the subject brightness and switch to a predetermined aperture. It is a difficult task for those who have few people. As a result, if the subject luminance is low, the photograph is not undershot unless the aperture is switched to the large aperture. If the subject brightness is high, the photograph is overexposed unless the aperture is switched to the small aperture. Would.

It is also difficult for a photographer to manually operate the power switch of the strobe by judging the brightness of the subject, and similarly, it is difficult for a person who has little experience in taking a picture. Nevertheless, you may forget to operate the power switch and make an under-photograph, or in spite of the high brightness, leave the strobe's power switch on and charge it unnecessarily, The battery may be consumed.

In Japanese Patent Application Laid-Open No. Hei 7-218993, since the strobe automatically emits light, the above-described problem concerning the strobe does not occur, but there is no mention of switching the aperture.

In view of such a problem, it is an object of the present invention to propose a film unit with a lens that can automatically switch the aperture according to the brightness of a subject.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is to provide a photometric circuit for detecting the level of a subject luminance with respect to a predetermined luminance in a film unit with a lens loaded with an unexposed film in advance, and a subject luminance detected by the photometric circuit. This is solved by providing aperture switching means for switching the aperture value depending on the height of the aperture.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 is an external perspective view of a film with a lens on which a flash circuit is mounted.

When the lens barrier knob 1 is slid rightward in the figure, a lens barrier (not shown) is retracted from the front of the taking lens 2, and at the same time, the internal flash main switch is turned on, and the internal flash circuit is turned on. Start charging. When the predetermined charging voltage is reached, it can be confirmed from the neon tube display window 3 that the neon tube is lit, and preparation for photographing is completed.

During this time, the light receiving element 4 measures the subject brightness, and when the brightness is higher than a predetermined brightness, the flash does not fire even when the release button 5 is pressed, but when the brightness is lower than the predetermined brightness, the flash fires, and the flash panel emits light. Irradiated from 6. After the end of flash photography, charging is started again, so that the flash is always usable.

FIG. 2 shows an embodiment of a strobe circuit.

When the two main switches SW1 are turned on, the battery B of the power supply is turned on, and a current flows from the transistor Tr1 to the primary coil 11a of the transformer 11 and the resistor R1. Then, a potential difference is generated between the base and the emitter of the transistor Tr1, the transistor Tr1 operates, and a current flows from between the emitter and the collector via the primary side coil 11b of the transformer 11. Therefore, this current is transmitted to the secondary coil 1 of the transformer 11 by mutual induction.
A current is generated in 1c, and depending on the ratio of the wire diameter and the number of windings of the transformer 11, for example, even if the primary battery voltage is 1.5V, the secondary voltage is increased to about 330V. This secondary voltage is rectified by the diode D and charged in the main capacitor 12 having a capacity of several hundred μF. When the main capacitor 12 is boosted to a predetermined voltage, the neon tube 1
3 lights up.

Here, CdS (cadmium sulfide) 14, which is a light receiving element, detects the luminance of the subject and, when the luminance is higher than a predetermined luminance, the resistance of CdS 14 itself decreases, so that the potential difference of the resistance R2 increases. Activate the high-voltage transistor Tr4, and transfer the charge of the trigger capacitor 16 charged together with the main capacitor 12 to the resistor R3.
Discharge via. Accordingly, the trigger switch S interlocked with the opening operation of the shutter sector (not shown)
Even if W2 is turned on, the charge of the trigger capacitor 16 does not flow to the trigger coil 17, and the xenon tube 18 does not emit light.

On the other hand, when the CdS 14 detects that the subject brightness is lower than the predetermined brightness, the CdS 14
Since the resistance of itself increases, the potential difference of the resistor R2 decreases, and the high breakdown voltage transistor Tr4 does not operate. Therefore, the charge of the trigger capacitor 16 does not discharge, and when the trigger switch SW2 is turned on, the charge of the trigger capacitor 16 flows to the primary side of the trigger coil 17, and
The secondary high voltage is applied to the trigger electrode 18a of the xenon tube 18.
, The xenon tube 18 emits light.

The light receiving element is not limited to CdS, and a photodiode or a photoelectric conversion element of silicon or selenium may be used.

Further, in the present embodiment, CdS1
4 is provided in parallel with the shape memory element 21. Also,
A transistor Tr5 having a collector connected to the shape memory element 21 and a base connected between the CdS 14 and the resistor R2 is provided. The operation of the transistor Tr5 is the same as that of the high-voltage transistor Tr4. The transistor Tr5 is activated when the CdS14 detects that the subject luminance is higher than a predetermined luminance, and the CdS14 detects that the subject luminance is lower than the predetermined luminance. Does not work when is detected.

Therefore, when the brightness is high, the shape memory element 21
, The shape memory element 21 self-heats due to the specific resistance, and is deformed into a high-temperature shape due to a rise in temperature due to the heat generation. When the brightness is low, the shape memory element 21 is not energized, so that the shape memory element 21 remains in the shape at normal temperature.

In this embodiment, the aperture is switched according to the change in the shape of the shape memory element 21. The configuration of this aperture switching will be described with reference to FIG. FIG. 3A is a view in which the aperture is set to a small aperture, and FIG.
(B) is a diagram in which the aperture is made large.

In FIG. 3, the aperture plate 22 is a small aperture 22a.
In addition, a through hole is formed to form a large stop 22b having an opening larger than the fixed stop 28 that determines the open F-number of the taking lens, and is attached rotatably about a support shaft 23.
The shape memory element 21 is fixedly attached at one end to the right side of the upper portion 22c of the aperture plate 22, and a tension spring 24 is fixed at one end to the left side of the upper portion 22c of the aperture plate 22. Installed.

As described above, when the brightness of the object is high, the shape memory element 21 is deformed into a shape at the time of high temperature, and FIG.
As shown in FIG. 7, the shape memory element 21 rotates the aperture plate 22 clockwise against the tension spring 24, and the aperture plate 22 is positioned in contact with the stopper 25. At this time, the aperture is switched to the small aperture 22a.

When the brightness of the subject is low, FIG.
As shown in (B), the shape memory element 21 is in a normal temperature state, the tension spring 24 rotates the aperture plate 22 counterclockwise, and the aperture plate 22 comes into contact with the stopper 26 and is positioned. At this time, the aperture is switched to the large aperture 22b.

The size of the aperture plate 22 is reduced instead of providing the large aperture 22b on the aperture plate 22, and FIG.
In this state, the diaphragm plate 22 may be completely retracted from the fixed diaphragm 28.

The configuration in which the aperture is switched as described above is particularly effective for a distant subject that cannot be irradiated with strobe light, and the morning and evening scenes do not become under.

If the shape memory element 21 performs both the action of pulling and the action of pushing out the upper portion 22c of the aperture plate 22, the tension spring 24 is not required.

Further, any shape memory element 21 can be used as long as it can move the aperture plate 22 depending on the presence or absence of a heat-generating action due to energization. However, for example, a shape memory alloy or a shape memory resin made of a Ti—Ni alloy can be used.

Here, as an example, the focal length is f = 30 m
m, the minimum circle of confusion is 0.05 mm, the small aperture is F11, the large aperture is F8, and the hyperfocal position is 1.
If it is 6m, the depth of field is F ~ 0.8 when F11
m and 5.9 m to 0.95 m at F8.

The photometric element is not necessarily CdS
The present invention is not limited to this, and a photodiode, a photoelectric conversion element of silicon or selenium can be used.

If shooting is not to be performed immediately after flash shooting as described above, the lens barrier knob 1 in FIG. 1 is operated to close the lens barrier and turn off the main switch SW1. However, when the lens barrier is left open, that is, when the main switch SW1 is left on, if the strobe circuit is not provided with a special countermeasure, the charged state is maintained and the battery is significantly consumed.

In this embodiment, in order to reduce the battery consumption, the circuit is configured as follows. That is, when the neon tube 13 is turned on, a current flows through the resistor R4 and the resistor R4
, A transistor Tr2 operates, and a current flows from the transistor Tr3 to the transistor Tr2.
When the current flows in this manner, a potential difference occurs between the base and the emitter of the transistor Tr3, and the transistor Tr3
Thus, a current flows to the primary side 11a of the transformer 11. Therefore, the potential difference between the base and the emitter of the transistor Tr1 disappears, the transistor Tr1 becomes inactive, no current flows to the primary side 11b of the transformer 11, and the oscillation by the transformer 11 stops. As a result, a large current does not flow from the battery B, and the consumption of the battery B is extremely small. Eventually, the electric charge of the main capacitor 12 gradually discharges, the voltage drops, and the neon tube 13 goes out.

When the neon tube 13 is turned off, the operation reverse to that described above is performed for each transistor, and the transistor Tr is turned off.
1 operates and the transformer 11 starts oscillating. As a result, the main capacitor 12 starts charging again, the neon tube lights up, and the transistor Tr2 operates again. As described above, while the transistor Tr2 is operating, the oscillation by the transformer 11 is stopped, so that the battery consumption is reduced.

In the above description, the aperture switching circuit is incorporated in the flash circuit of the automatic light emission type. However, the aperture switching circuit may be independent of the flash circuit by using only the power supply in common. FIG. 4 shows this circuit diagram.

Reference numeral 31 denotes a flash circuit, which may be any flash circuit.
Is turned on, the battery is charged by the battery B of the power supply. On the other hand, the switch SW4 is a switch that is turned on at the first stage of the release operation of the release button that can be operated in two steps in the pressing direction. When the subject luminance is high as described above, the resistance of the CdS 32 itself becomes small. Resistance R
6, the transistor Tr6 is activated, and the shape memory element 33 is energized, so that the shape memory element 33 self-heats due to its intrinsic resistance and is deformed into a high-temperature shape due to a rise in temperature due to the heat generation. When the luminance of the object is low, the transistor Tr6 does not operate and the shape memory element 33 is not energized, so that the shape memory element 33 keeps its shape at room temperature. Such a shape memory element 33
The aperture may be switched according to the difference in the shape of.

The shutter release is performed by the second release operation of the release button.

The shape memory element 21 and the transistor Tr5 in FIG. 2 and the shape memory element 33 in FIG.
By incorporating the transistor Tr6 and the transistor Tr6 into a printed circuit board of a strobe circuit, wiring can be performed with the same printed circuit board pattern, and the number of wiring steps is reduced.

In the above description, the aperture is switched by the shape difference of the shape memory element. However, a solenoid may be used instead of the shape memory element. That is, a solenoid is used in place of the shape memory element 21 in FIG. 2 and the shape memory element 33 in FIG. 4, and the position of the plunger changes depending on whether or not the solenoid is energized, so that the aperture can be switched.

[0039]

According to the film unit with a lens according to the first, fourth, and fifth aspects, the aperture is automatically switched according to the level of the luminance without taking the luminance of the subject into account during photographing. Photos are reduced.

According to the film unit with the lens according to the second aspect, since wiring can be performed with the same pattern on the printed circuit board, the number of wiring steps is reduced, and the strobe and the photometric circuit can easily share a battery.

According to the film unit with the lens according to the third aspect, the aperture is automatically switched according to the level of the luminance without taking the luminance of the subject into account at the time of photographing, and the strobe light is also automatically emitted. Under- and over-photos are reduced.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a lens-equipped film on which a strobe circuit is mounted.

FIG. 2 is a diagram in which an aperture switching circuit is mounted on a strobe circuit diagram.

FIG. 3 is a diagram showing a configuration of aperture switching.

FIG. 4 is a circuit diagram in which a strobe circuit diagram and an aperture switching circuit diagram are made independent.

[Explanation of symbols]

 B battery SW1 main switch SW4 switch Tr4 high voltage transistor Tr5, Tr6 transistor R2, R6 resistance 1 lens barrier knob 14, 32 CdS 21, 33 shape memory element 22 aperture plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroshi Kibayashi Konica Corporation, 1 Sakuracho, Hino City, Tokyo

Claims (5)

[Claims] 1. A photometric circuit for detecting a level of subject brightness with respect to a predetermined brightness in a film unit with a lens loaded with an unexposed film in advance, and a diaphragm for switching an aperture value according to the level of subject brightness detected by the photometric circuit. A film unit with a lens, comprising a switching unit. 2. The film unit with a lens according to claim 1, further comprising a built-in strobe, wherein the photometric circuit is provided on a circuit board for the strobe. 3. The lens-equipped film unit according to claim 1, further comprising a built-in strobe, wherein the strobe automatically emits light depending on the level of the subject brightness detected by the photometric circuit. 4. The lens-fitted film unit according to claim 1, wherein the aperture switching means switches the aperture based on a difference in shape of the shape memory element depending on the presence or absence of energization. 5. The aperture switch according to claim 1, wherein the aperture switching means switches the aperture based on an operation of a solenoid.
4. The film unit with a lens according to any one of items 3 to 5.