JPS599643A - Automatic trigger device of shutter for camera - Google Patents

Abstract

PURPOSE:To evade malfunction and to perform accurate operation even when the brightness of field light to be used for photographing is low, by providing a control circuit which turns on a light emitting element through the operation of a switch and turns off it through the operation of an automatic triggering circuit. CONSTITUTION:The switch 22 is closed by the 2nd-stage operation of a release button. At this time, shutter sectors 1 are still closed, so the light emitting element 18 is turned on by a photodetecting element 4 which receives light transmitted through a subordinate opening, and its bright luminous flux from the element 18 is reflected by a half-mirror 19 to open an AND gate 12, so that the shutter sectors 1 are attracted and held at opening positions. The subordinate opening 2 is shielded a slight delay time later synchronously with the opening of the shutter sectors 1, so the photodetecting element 14 is turned off temporarily to set an FF15. Consequently, the AND gate 12 is closed to release the shutter sectors 1 from being held at the opening positions and to close the shutter sectors 1 obtaining proper exposure. Thus, malfunction is evaded and the accurate operation is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic trigger device for a camera shutter.

Conventional automatic exposure control devices for cameras have been proposed in which the opening or closing of a mechanical switch operates an integrating or counting circuit that sets the appropriate exposure time based on field light brightness information. When using such a mechanical switch, it is necessary to adjust the operating timing of the switch using a fine adjustment means, which is troublesome and may cause errors.

It has also been proposed to set the timing of the automatic exposure time control circuit in a sequential manner in relation to the release operation, and start the operation of the integrating or counting circuit. The timing at which the blades begin to open is deviated due to the influence of power supply voltage, temperature, humidity, etc., and there is a drawback that accurate exposure time cannot be obtained.

On the other hand, a predetermined amount of light is allowed to pass through the sub-aperture for photometry in the closed state of the shutter blade, and after the sub-aperture is temporarily blocked from light when the shutter starts to open, the amount of light passing through is controlled in accordance with the shutter blade, and the light is received through the sub-aperture. An auto-trigger device has also been developed in which the photometry circuit detects the above-mentioned light blocking and starts the operation of the integrating or counting circuit, but when the field light brightness is low, it is difficult to detect the above-mentioned light blocking of the sub-aperture, resulting in malfunction. However, there were disadvantages such as problems such as errors or inaccurate operation timing.

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide an auto-trigger device for a camera shutter that reliably avoids malfunctions and enables accurate operation even when field light brightness is low. do.

The auto-trigger device for a camera shutter according to the present invention allows a predetermined amount of light to pass through the sub-aperture for receiving the passing light to the light-receiving element of the photometry circuit when the main aperture light amount control shutter blade for photography is closed, and is activated by the release operation. The amount of light passing through the sub-aperture is once reduced in conjunction with the opening operation of the shutter blades started by the switch that is opened, and then the amount of light passing through the sub-aperture is controlled in response to the opening operation of the shutter blades, and the reduction in the amount of light passing through the sub-aperture is controlled. In an auto-trigger device for a camera shutter, an auto-exposure time setting circuit is actuated by an auto-trigger circuit detected and actuated via a photometry circuit to close a shutter blade to obtain proper exposure, and the luminous flux is directed to the sub-aperture. The present invention is characterized in that a light emitting element is disposed so that the light is incident on the light emitting element, and a control circuit is provided which energizes the light emitting element when the switch is operated and energizes the light emitting element when the auto trigger circuit is operated.

With this structure, the light emitting element emits light when the shutter blade is opened by the release operation, and even if the brightness of the field light is low (even if the brightness of the field light is low), the emitted light flux of the light emitting element will cause the light to pass through the sub-aperture for a sufficient period of time. Since bright light is given to the light receiving element, it is possible to reliably detect that the amount of light passing through the sub-aperture is temporarily reduced when the shutter blade is actually opened, and then the light emitting element is activated, so the automatic exposure time setting circuit This allows for accurate operation.

In the present invention, the luminous flux of the light emitting element is further reflected or transmitted by a half mirror disposed in front of the sub-aperture, and is incident on the sub-aperture together with field light transmitted or reflected by the half mirror. None, the wavelength selectivity of the mirror is set so that the field light incident on the sub-aperture ranges from green to yellow, and the luminous flux of the light-emitting element incident on the sub-aperture ranges from red to near-red. Set it so that it is outside the range, and when emitting spectroscopy of the light emitting element.
By setting the light in the range of approximately red to near infrared, the half mirror selects light in the field light wavelength range that matches the visibility and efficiently inputs it into the double opening for accurate accuracy. It makes it possible to set the exposure time, and also improves efficiency by matching the emission spectral characteristics of the light emitting element with the wavelength selectivity of the half mirror (
By making it possible to utilize the luminous flux of the light emitting element, it is possible to use a light emitting element with a small capacity, thereby making it possible to save energy.

Furthermore, in the present invention, the luminous flux of the light emitting element is reflected or transmitted by a half mirror disposed in front of the sub-aperture, and together with field light transmitted or reflected by the half mirror, the luminous flux of the light emitting element is reflected or transmitted by the half mirror disposed in front of the sub-aperture. The wavelength selectivity of the half mirror is set so that the spectral sensitivity of the light-receiving element due to the incident light matches the visibility, and the photometry of field light that matches the visibility is possible. This makes it possible to obtain high image quality, and eliminates the need for a visibility correction filter, which was conventionally required.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a circuit diagram of an automatic trigger device for a camera shutter according to the present invention.

In FIG. 1, the main aperture for photographing whose amount of incident light is controlled by the shutter blade 1 is not shown, and the diaphragm (not shown) provided on the shutter blade 1 closes the main aperture. When the main aperture is open, a predetermined amount of light is allowed to pass through the sub-aperture 2 for photometry, and when the shutter blade 1 actually starts to open the main aperture, the light passing through the aperture 20 is temporarily blocked, and then the main aperture is opened by the shutter blade 1. The amount of light passing through the sub-aperture 2 is controlled accordingly. When the suction type electromagnetic coil 3 is energized, it attracts the shutter blade 1 and moves it to the main opening opening position, and works to attract and hold the shutter blade 1 at that position. The suction hold is released and a closing action is applied to complete the exposure.

Now, in FIG. 1, a light receiving element 4 such as a silicon conformophotodiode is arranged behind the sub-aperture 2, and both terminals of the light receiving element 4 have a feedback element 5 such as a logarithmic compression diode connected in feedback. It is connected to both input terminals of the amplifier 6, and the positive terminal is connected to the amplification degree nt4 (grounded via a node variable resistor 7).The output of the operational amplifier 6 is connected to an NPN transistor 8 such as a logarithmic expansion transistor. , whose emitter is grounded, and whose collector is connected to the other end of an integrating capacitor 9 whose one end is connected to the power supply voltage Vcc, and whose negative input terminal is connected to the reference voltage Vref. The output of the comparator 10 is connected to the positive input terminal of a comparator 10 which is connected to the first input terminal a. The second of the AND gates 12 connected
The output of the AND gate 12 is connected via the drive circuit 13 to one end of the attraction type electromagnetic coil 3 described above, and the other end thereof is connected to the power supply voltage VCC.

The output of the operational amplifier 6 is also connected to the input of the auto-trigger circuit 14, the output of which is connected to the input terminal S of the flip-flop 150, and the non-inverting output terminal Q is connected to the input terminal S of the flip-flop 150 set. This PNP type transistor 17 is connected to the base of the PNP type transistor 17 for shorting the capacitor.
The collector and emitter of are connected across the integrating capacitor 9 and the transistor 17
When the voltage is cut off, charging of the capacitor 9 is started, and the exposure amount is integrated. Auto trigger circuit 1 mentioned above
4 emits an output pulse to set the flip-flop 15 when the sub-aperture 2 is shielded from light, the light-receiving element 4 is deenergized, and the output of the operational amplifier 6 is reduced.

The above-mentioned light receiving element 4 and operational amplifier 6 constitute a photometry circuit for field light brightness in the present invention, and the integral condenser 9 is used for automatic exposure time setting to calculate the appropriate exposure time based on the output of the photometry circuit. It constitutes a circuit.

According to a feature of the invention, a light emitting element 18, such as a light emitting diode, is provided, the positive terminal of which is connected to the output of the AND gate 21 via the light emitting element drive circuit 20, and the negative terminal of which is grounded. Light emitting element 180 luminous flux is a half mirror
19 and enters the sub-aperture 2 together with the field light that passes through the half mirror 19.

One input terminal α of this AND gate 21 is connected to the inverted output terminal Q of the above-mentioned Flip Flora 1150, and the other input terminal is the first stage of the release for preliminary operations such as power supply connection, battery check, camera shake warning, etc. (The output terminal is connected to the output terminal Q of a flip-flop 23 whose input terminal is connected to a switch 22 that is closed in conjunction with the second-stage operation of the release that opens the shutter blade after operation.) Q is connected to the third input terminal C of the AND gate 12 mentioned above.

The operation of the auto-trigger device according to the present invention configured as described above is as follows.

The first step operation in conjunction with the release actuates a closing switch (not shown), which performs a series of well-known preliminary operations such as power connection, camera shake warning, etc., and then the second step operation of the release activates the closing switch (not shown). Switch 2 mentioned above
2 is closed. As a result, the flip-flop 23 is activated, and the output Q at the H level is inputted to the input terminal CK of the AND gate 12 and inputted to the input terminal S of the AND gate 21.

At this time, the output of the operational amplifier 6 is at H level due to the tear resistance of the light receiving element 4 caused by the light passing through the sub-aperture from ℃°C, when the shutter blade 1 is not yet opened, and the auto trigger circuit 1
The output of gate 4 is at L level and flip-flop 15 is in a reset state, and the inverted output page at H level is output from AND gate 2.
10 is input to input terminal α, and gate 21
opens, the light emitting element 18 is energized via the drive circuit 20, and its bright luminous flux is reflected by the half mirror 19 and enters the sub-aperture 2, and the non-inverting output of the flip-flop 15 at L level. Q is drive circuit 1
6 to the base of the PNP transistor 17, which is kept conductive and the capacitor 9 is short-circuited.
The power supply voltage Vcc at H level is applied to the positive input terminal of the comparator 10, and the output of the comparator 10 is at H level, which is applied to the input terminal of the AND gate 12. Since the is set to H level, the AND gate 12 is opened and the electromagnetic coil 3 is energized to start holding the shutter blade 1 in the open position. Shutter blade 1 after some mechanical delay time
Since the sub-aperture 2 is temporarily blocked from light in synchronization with the actual opening of the sub-aperture 2, the light-receiving element 4 is temporarily deenergized, the output of the operational amplifier 6 is reduced, and the auto-trigger circuit 14 detects this. An output pulse is generated to set the flip-flop 15. As a result, the flip-flora 1150 inverted output enable becomes L level, which is the input terminal α of the AND gate 21.
is applied to close the AND gate 21, turn off the light emitting element 18 and extinguish it, and at the same time cut off the ptip type transistor 17 with the non-inverting output Q which has become H level and release the short circuit of the capacitor 9. A current flows through the transistor 8 in accordance with the output voltage of the operational amplifier 6, which is related to the photocurrent of the light receiving element 4 corresponding to the amount of light passing through the sub-aperture 20 corresponding to a certain shutter blade 1, and the power supply voltage Vcc causes a current to flow into the capacitor 9. is charged with a charge proportional to the integrated amount of light, and therefore the potential at the connection point d drops, and when it becomes equal to the reference voltage Vref, the output of the comparator 10 becomes L level and the AND gate 12
The electromagnetic coil 3 is deenergized, the shutter blade 1 is released from being held in the open position, and the shutter blade is closed to provide proper exposure.

FIG. 2 shows a time chart of the circuit described above.

Curve A shows the operating state of the above-mentioned switch operated by the first stage operation of the release.

Curve B shows the operating state of switch 22.

Curve C shows the energization state of the light emitting element 18.

The curved line indicates the output state of the operational amplifier 6.

Curve E shows the amount of light passing through the sub-aperture 20.

Curve F shows the output state of the auto-trigger circuit 14.

Curve G shows the state of non-inverting output Q of flip-flop 15.

Curve H shows the voltage state of the 4-part capacitor 9.

The curve ■ indicates the energized state of the electric coil 3.

Finally, curve J shows the waveform diagram of the main aperture opening of the shutter blade 1.

As mentioned above, when using a half mirror, part of the field light is reflected and escapes, and part of the light emitted by the light emitting element is transmitted and escapes, so the entire light area of each can be used effectively. However, it is inevitable that the amount of light will be insufficient.

In order to avoid the above-mentioned light shortage, the present invention provides wavelength selectivity to the half mirror and preferentially transmits field light in the range of green to yellow that is easily felt by the human eye, thereby efficiently capturing images. In addition to utilizing field light, by doing this, the reflection spectral characteristics of the half mirror will inevitably preferentially reflect the range from red to near infrared, and in order to effectively utilize this, light emitting elements The emission spectral characteristics of the luminous flux of the light-emitting element are set to the range from red to near-infrared, so that most of the luminous flux of the light-emitting element is efficiently reflected and used efficiently, and the ability of the light-emitting element itself is reduced. C,
This makes it possible to save energy.

Furthermore, in the present invention, the wavelength selectivity of the half mirror is set so that the spectral sensitivity of the light receiving element that receives the field light after passing through the half mirror exactly matches the human visibility characteristics. By doing so, it is possible to obtain image quality that most closely matches human visibility.

By doing this, there is no need to use a separate visibility correction filter or the like.

FIG. 3 shows the spectral characteristics of the above-mentioned half mirror.

The song is indicates the spectral sensitivity characteristics of the light receiving element.

The curve α shows half mirror transmission spectral characteristics.

The curved line indicates half-mirror reflection spectral characteristics.

Curve C shows the spectral sensitivity of the light receiving element due to the light transmitted through the half mirror. It can be seen that this makes it possible to control exposure so as to obtain a single image quality that matches the visibility.

Curve d shows the spectral sensitivity of the light receiving element due to half mirror reflected light. As a result, even if the light emitting element has a small capacity, the luminous flux of the light emitting element at the beginning of the shutter blade opening is used most effectively, and by turning off the light in synchronization with the opening of the shutter blade, reliable shutter blade opening detection is possible. I understand that.

FIG. 4 shows an example of the actual arrangement of the light-emitting element 8, half mirror 19, shooting blade 1, sub-aperture 2, and light-receiving element 4 described above. In the drawing, 24 is a lens, 25 is an ASA conversion ND filter, 26 is a light guide, 27 is a shutter blade holding plate, and 28 is a shutter base plate.

In the above example, the field light is transmitted through a half mirror,
The light emitted from the light emitting element is reflected by the half mirror, but the spectral characteristics of the half mirror are reversed so that the field light is reflected from the half mirror f and the light emitted from the light emitting element is transmitted. obtain.

FIG. 5 shows a modification in which the luminous flux of the light emitting element is incident on the light receiving element together with the field light without using a half mirror. In this case, the light guide 26' is provided with a field light receiving end 26'α and a light emitting element emitted light flux receiving end 26'h so that both incident lights are made to enter the light receiving element 4 from the exit end 26'C. It is. In this case, it is not possible to obtain the above-mentioned wavelength selectivity with a half mirror, so it is recommended to use a visibility correction filter in combination. Reliable detection of the start of opening of the shutter blades can be performed in exactly the same manner as in the previously described embodiments.

Furthermore, in the above example, when the shutter blades are tilted, the electromagnetic coil 3 is energized to open the shutter blades and hold them in the open position.First, the shutter blades are opened by the attraction action of the electromagnet, and then held in the open position by the attraction action. However, the opening operation of the shutter blade is applied in synchronization with the above-mentioned second-stage operation of the release, and the shutter blade is opened after a slight mechanical delay time, and the shutter blade is attracted and held in the open position by a pre-energized electromagnet. It is also possible to use a mechanical release attraction type electromagnet, and in this case, the electromagnet coil 3 is equipped with a second
As shown by ``■'' in the figure, the electromagnetic coil 3 can be energized in synchronization with the first stage operation of the release.

As mentioned above, the present invention reliably eliminates the malfunction or inaccurate operation when the field brightness is low, which was a drawback of the conventional auto-trigger type shutter, and it is possible to obtain reliable and good image quality. This makes it possible to obtain excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an automatic trigger device for a camera shutter according to the present invention. FIG. 2 is an operation time chart of the circuit shown in FIG. FIG. 3 is a diagram showing the spectral characteristics of a half mirror and a light receiving element. FIG. 4 is a partial explanatory diagram showing an example of the arrangement of the light emitting elements and half mirrors shown in FIG. 1. FIG. 5 is a partial explanatory diagram showing a modification of FIG. 4 without using a half mirror. ■・・・Shutter blade 2・・・・Sub-aperture for photometry 3・・・・Electromagnetic coil 1・・・・ Photodetector 6・・・・・・ Arithmetic amplifier 8... NPN type transistor 9...
... Integral condenser? - 10... Comparator 11... Cutoff seconds circuit 12.21... AND gate 14... Auto trigger circuit 15.23... Flip-flop 17...
PNP transistor 18... Light emitting element 19... Half mirror 22... Switch 24... Lens 26.26'... Light guide

Claims (1)

[Scope of Claims] (11 Main aperture control for photography) With the shutter blades closed, a predetermined amount of light is passed through the sub-aperture for receiving the passing light by the light-receiving element of the photometry circuit, and is activated by the release operation. When the shutter blades are opened by the switch, the amount of light passing through the opening is once reduced, and then the amount of light passing through the sub-aperture is controlled in response to the opening operation of the shutter blades, and the amount of light passing through the sub-aperture is reduced. In an auto-trigger device for a camera shutter, an auto-exposure time setting circuit is actuated by an auto-trigger circuit detected and actuated via a photometry circuit to close a shutter blade to obtain proper exposure, and the luminous flux is directed to the sub-aperture. An automatic trigger for a shutter for a camera, characterized in that a light-emitting bare hand is disposed so that the light enters the light, and a control circuit is provided for energizing the light-emitting element by operating the switch and deenergizing it by operating the auto-trigger circuit. Apparatus 0 (2) The luminous flux of the light emitting element is reflected or transmitted by a nof mirror disposed in front of the sub-aperture, and the field light transmitted or reflected by the nof mirror enters the sub-aperture. The wavelength selectivity of the -7 mirror is adjusted so that the field light incident on the sub-aperture is approximately in the green to yellow range, and the luminous flux of the light-emitting element incident on the sub-aperture is Claim 1, characterized in that the light emitting element is set so as to fall within a range from approximately red to near infrared, and the emission spectral characteristics of the light emitting element are set within a range from approximately red to near infrared. Auto-trigger device for camera shutter. (3) The luminous flux of the light emitting element is reflected or transmitted by a half mirror disposed in front of the sub-aperture, and the field light transmitted or reflected by the half mirror is combined with the sub-aperture. Claim (1) characterized in that the wavelength selectivity of the half mirror is set such that the spectral sensitivity of the light receiving element due to the incident light matches the luminous sensitivity. Auto-trigger device for the camera shutter described.