JPS6243171B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aperture control device capable of auto-fading photography, and in particular, an aperture control device that operates an aperture member using a stepping motor to automatically perform fade-out and fade-in fading. The present invention relates to an aperture control device capable of auto-fading photography.

Already, automatic exposure amount control devices that operate an aperture member according to changes in subject brightness to always obtain an appropriate exposure amount include a stepping motor or a driving means for operating the aperture member according to changes in subject brightness. Motors that utilize a motor called a pulse motor (hereinafter referred to as a stepping motor) are known. As is well known, the operation of a stepping motor is controlled by a pulse signal, and its driving speed is determined by the frequency of the pulse signal. Therefore, in an automatic exposure amount control device using such a stepping motor, the diaphragm member must be operated at high speed to follow the ever-changing subject brightness. There is a need for a pulse signal oscillator that emits high-frequency pulse signals to control the operation of the stepping motor.

By the way, the present invention is an automatic exposure amount control device configured as described above, which uses an aperture member, that is, forcibly operates the stepping motor, to perform fade-out and fade-in fading. The present invention relates to an aperture control device capable of performing fading photography.

As is well known, when fading is performed using an aperture member, unless there is a high-brightness object that is significantly different from the rest in the subject, the appropriate exposure aperture value and an aperture value that is about 4 to 5 steps under from this aperture value should be used. Substantial fading is achieved in the range between. In other words, the fade out is
By stopping down the aperture to an aperture that is approximately 4 to 5 steps under from the appropriate exposure aperture, the image becomes almost completely dark, and the fade-in is essentially completed by stopping down to an aperture that is approximately 4 to 5 steps under from the appropriate exposure aperture. An image begins to appear from the closed side to the open side, and a substantial fade-in begins. It goes without saying that if there is a high-brightness object in the subject that is noticeably different from others, that high-brightness object will remain or appear in the image even at aperture values below the above aperture value range. Nor. Therefore, the aperture member operation in an autofading device is such that the aperture value changes at a slow speed in the range between the appropriate exposure aperture value and an aperture value approximately 4 to 5 steps below this aperture value, and the aperture value changes at a slow speed. It is desirable that the aperture value changes rapidly from the aperture value to the closed aperture value.

However, constructing an auto-fading device using a part of the automatic exposure amount control device as described above is difficult because the aperture member is controlled by a stepping motor controlled by a high-frequency pulse signal. Since it is configured to be operated, the throttle member is operated at a consistently high speed from beginning to end, resulting in a disadvantage that the fading time is extremely short.

Therefore, in view of the above, the present invention provides
To provide an auto-fading device that operates an aperture member at a low speed within a certain period of time after the start of fade-out, and operates the aperture member at a low speed within a predetermined time after a certain period of time has elapsed after the start of fade-in. It is something to do.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An autofading device according to the present invention will be described in detail below based on an embodiment shown in the accompanying drawings.

The drawing is a circuit diagram showing an embodiment of an aperture control device capable of auto-fading photography according to the present invention.

In the drawing, R _X is a well-known TTL (Through the Taking
Lens) A photoreceptor such as CdS for photometry, R _V1 is a first variable resistor set according to the photosensitivity of the film used, R _V2 is a second variable resistor to be described later,
R ₁ to R ₃ are fixed resistors, and these form a bridge circuit connected to the power supply E via the main switch SW ₀ as shown in the figure, and depending on the brightness of the subject light incident on the photoreceptor _R It is configured to apply an unbalanced output signal to the first and second comparators COM ₁ and COM ₂ in the next stage. The respective output terminals of the first and second comparators COM ₁ and COM ₂ are connected to the first flip-flop circuit forming the next stage flip-flop circuit.
and one input terminals a and c of the second NAND gate circuits NG ₁ and NG ₂ . Furthermore, resistor
_R4 and _R5 are pull-up resistors. Further, the output terminals of the first and second NAND gate circuits NG ₁ and NG ₂ are connected to the first and second inverters, respectively.
It is connected to one input terminal e and g of the third and fourth NAND gate circuits NG ₃ and NG ₄ via INV ₁ and INV ₂ . Furthermore, in the drawings, 20 is a stepping motor drive circuit, and the circuit 20 includes:
Said third and fourth NAND gate circuits NG ₃ and NG ₄
The stepping motor is operated by output signals from the stepping motor, and is configured to sequentially excite drive coils _L1 to _L4 , which are representative of the stepping motor. Furthermore, in the same drawing, COM ₃ and COM ₄ indicate third and fourth comparators, and one input terminals i and k of these third and fourth comparators COM ₃ and COM ₄
is connected between the fixed resistor _R3 and the second variable resistor _R4 of the bridge circuit, and the other input terminals j and l are connected to the first and second mode changeover switches _SW1 and SW, respectively. Connected to ₂ . Said first and second mode changeover switches SW ₁ and SW ₂
is a switch operated by one common operating member (not shown), and is configured to be able to switch to three shooting modes: normal shooting, fade-out shooting, and fade-in shooting. In other words, the first mode changeover switch SW ₁ is normally connected to the grounded fixed terminal C when the movable contact A connected to the other input terminal d of the second NAND gate circuit NG ₂ is connected to the neutral terminal B. In this state, you can take fade-out shots, and
When connected to the fixed terminal d connected to the input terminal j of the third comparator COM ₃ , fade-in photography is performed. Further, the second mode changeover switch _SW2 is connected to the fourth comparator.
Normal shooting is performed when the movable contact piece E connected to the input terminal L of COM _{4 is connected to the grounded fixed terminal, fade-out shooting is performed when the movable contact piece E connected to the input terminal L of COM 4} is connected to the fixed terminal G connected to the positive side of the power supply E, and The bridge circuit is configured to perform fade-in photography when connected to a fixed terminal connected to one terminal of the bridge circuit. In addition, the first mode changeover switch
A switch SW ₃ which grounds the fixed terminal of SW ₁ is a fade-in start switch, and is interlocked with the operating member to connect the first and second changeover switches SW ₁ and SW _2.
The camera is configured to turn on when the camera is brought to the fade-in shooting mode position, and to turn off when shooting starts. Also, in the same drawing, Tr ₁ is a switching transistor, and this transistor
Tr ₁ has its base terminal connected to the output terminals of the third and fourth comparators COM ₃ and COM ₄ . Furthermore, Tr ₂ and Tr ₃ represent transistors that constitute a monostable multivibrator together with the capacitor C ₁ and the resistors R ₆ to R ₁₀ . In addition, C ₂ is
This is a trigger capacitor that triggers the monostable multivibrator mentioned above. The output terminal of the monostable multivibrator is connected to the input terminal of the third inverter INV ₃ , and the fourth inverter INV ₄ is connected to one input terminal m and o of the fifth and sixth NAND gate circuits NG ₅ and NG ₆ in the next stage. connected via or directly. The fifth and sixth NAND gate circuits
NG ₅ and NG ₆ have one input terminal n and p connected to a first pulse signal oscillator OSC ₁ that oscillates a high frequency pulse signal and a second pulse signal oscillator OSC ₂ that oscillates a low frequency pulse signal. , and their respective output terminals are connected to the other input terminals f and h of the third and fourth NAND gate circuits NG ₃ and NG ₄ .

Next, we will explain the operation of the aperture control device configured as above, which is capable of auto-fading photography, during normal photography.
Operations in three shooting modes, auto fade-out shooting and auto fade-in shooting, will be explained separately.

First, during normal shooting, the operation of the aperture control device capable of auto-fading shooting is performed by using an operating member to switch the first and second modes.
SW ₁ and SW ₂ are in the normal shooting position as described above, that is, the movable contact A of the first mode changeover switch SW ₁ is connected to the neutral terminal B, and the movable contact E of the second mode changeover switch SW ₂ is connected to the grounded fixed terminal. After setting the main switch SW ₀ to the position where it is connected to Operate to open to. In other words, an aperture control device that is configured as described above and capable of auto-fading photography will:
The output of the first comparator COM ₁ is "1", the output of the second comparator COM ₂ is "0", the output of the first NAND gate circuit NG ₁ is "0", the output of the second NAND gate circuit NG ₂ is "1", The output of the first inverter INV ₁ becomes "1" and the output of the second inverter INV ₂ becomes "0". Furthermore, at this time, the fourth comparator
Since the output of COM ₄ is "0", the monostable multivibrator is inactive, the output of the third inverter INV ₃ is "1", the output of the fourth inverter INV 4 is "0", and the output of the fourth inverter INV ₄ is "0". A pulse signal of "1" from the first pulse signal oscillator OSC ₁ is applied to one input terminal f and h of the third and fourth NAND gate circuits NG ₃ and NG ₄ via the fifth NAND gate circuit NG ₅ . Therefore, the third NAND gate circuit _NG3 is connected to the first NAND gate circuit NG3.
Since the output of the inverter INV ₁ is "1", the output becomes "0", and the stepping motor drive circuit 20 is operated to move the aperture member 10 toward the closing side. Also, if the subject brightness becomes lower than the balanced state, the first comparator COM ₁
The output of the second comparator COM ₂ is "1", the output of the first NAND gate circuit NG ₁ is "1", the output of the second NAND gate circuit NG ₂ is "0", the first inverter INV ₁ The output of the second inverter INV 2 becomes "0" and the output of the second inverter INV ₂ becomes "1".
Therefore, the fourth NAND gate circuit _NG4 has the first pulse signal oscillator connected to one input terminal h as described above.
Since the pulse signal "1" from OSC ₁ is applied and the output of the second inverter INV ₂ is "1", the output becomes "0", and the stepping motor drive circuit 20 is operated to open the aperture member 10. Operate to the open side.

The above description of the operation is the so-called automatic exposure amount control operation in normal photography.Next, the operation in auto-fading photography will be explained.

First, let's talk about the case where auto-fade-out photography is performed following normal photography. To perform auto-fade-out photography following normal photography, rotate the operating member counterclockwise and press the first and second mode selection switch SW ₁ . By setting SW ₂ to the auto-fade-out shooting position, the auto-fade-out shooting can be performed.

That is, with the above settings, this aperture control device capable of auto-fading photography has the following circuit configuration and operates as described below.

By rotating the operating member in the counterclockwise direction, the first mode changeover switch SW ₁ becomes in a state where its movable terminal A is connected to the grounded fixed terminal C, and the output of the first inverter INV ₁ is changed to "1'', the output of the second inverter INV ₂ is set to ``0'', and the input signals of the first NAND gate circuit NG ₃ and the second NAND gate circuit NG ₄ are determined as if the subject brightness had become higher than the balanced state. Also, by the above operation, the second mode changeover switch SW ₂ becomes in a state where its movable contact HO is connected to the fixed terminal GH, and the fourth
Invert the output of comparator COM ₄ to "1". The output of this fourth comparator COM ₄ is "1"
As a result, the monostable multivibrator operates, and the third inverter operates for a predetermined time determined by this monostable multivibrator.
The output of INV ₃ becomes "0". Therefore, one input terminal f and h of the third and fourth NAND gate circuits NG ₃ and NG ₄ receives a pulse signal of "1" from the second pulse signal oscillator OSC ₂ via the sixth NAND gate circuit NG ₆ . The voltage is applied within the time determined by the monostable multivibrator, and after that, the output of the third inverter INV ₃ is inverted to "1", and the voltage is applied to the input terminals f and h as in normal shooting. A pulse signal of "1" from the first pulse signal oscillator OSC ₁ is applied via the fifth NAND gate circuit NG ₅ .

Therefore, when shooting auto fade-out, the third NAND gate circuit NG ₃
The output signal "1" of the first inverter INV ₁ is applied to one input terminal e of the inverter, and the second pulse is applied to the other input terminal f within a predetermined time determined by the monostable multivibrator. signal oscillator
A low frequency pulse signal "1" from the OSC ₂ is applied, and then a high frequency pulse signal "1" from the first pulse signal oscillator OSC ₁ is applied again. Therefore, the stepping motor drive circuit receives the "0" output signal from the third NAND gate circuit _NG3 , and controls the aperture member 10 to the second state at an initial predetermined time determined by the monostable multivibrator. The low frequency pulse signal from the pulse signal oscillator OSC ₂ causes the operation to close at a low speed, and after a predetermined time, the high frequency pulse signal from the first pulse signal oscillator OSC ₁ causes the operation to close at a high speed. Work to make it work.

Next, we will discuss the case of fade-in photography. For fade-in photography, rotate the operating member clockwise and press the first and second mode changeover switch SW _1.
This can be done by operating the shutter release after setting SW ₂ to the auto fade-in shooting position.

That is, this aperture control device capable of auto-fading photography has the following circuit configuration and operates according to the above settings, thereby achieving auto-fade-in photography.

By operating the operating member, the first mode changeover switch _SW1 is brought into a state in which its movable part A is connected to the fixed terminal D connected to one input terminal j of the third comparator _COM3 , and the The two-mode changeover switch _SW2 is in a state in which the movable contact H is connected to the fixed terminal H connected to one output terminal of the bridge circuit. Further, by the above operation, the fade-in start switch _SW3 is also turned on.

In the above setting state, the main switch SW ₀ is turned on by the shutter release operation, and the output of the first inverter INV ₁ becomes "1" because its input is grounded by the fade-in start switch SW ₃ . Therefore, the aperture member 10 operates in the same manner as when the subject brightness becomes higher than the balanced state during normal photographing, and the diaphragm member 10 is moved to the close side and maintains the closed state. Photography is started by the subsequent shutter release operation, and the fade-in start switch SW ₃ is turned on, and the aperture control device capable of auto-fading photography, which is set as described above, operates the aperture member 10 as follows. It operates to perform fade-in photography and normal photography following the fade-in photography.

As mentioned above, fade-in start switch SW ₃
is turned off and the aperture member 10 is in the closed state, so that the bridge circuit is unbalanced, and the unbalanced output signal causes the output of the first comparator COM ₁ to be "0" and the output of the second comparator COM to be "0". ₂ output is “1”, first NAND gate circuit
The output of NG ₁ is "1", the second NAND gate circuit NG ₂
The output of the first inverter INV ₁ is "0", the output of the second inverter IND ₂ is "1", and the fourth NAND gate circuit NG ₄ receives the input signal "0" at one input terminal h. 1'' is applied, the stepping motor drive circuit 20 is operated and preparations are made to operate the aperture member 10 toward the open side. On the other hand, when the fade-in start switch SW ₃ is turned off, the third comparator COM ₃ is inverted and the output becomes "1", and the fourth comparator COM ₄
The output is "0" only for the first certain period of time, and then becomes "1". The above-mentioned first fixed time is determined by the second variable resistor R _V2 ,
This second variable resistor R _V2 is set based on the midpoint potential of _the photoreceptor _R
It is set to correspond to the aperture value of the step-under.

As the output of the fourth comparator COM ₄ changes as described above, the monostable multivibrator does not operate until a certain period of time has passed after the start of fade-in, and as described above, the first pulse signal oscillator OSC ₁
A higher frequency pulse signal "1" is applied to one input terminal h of the fourth NAND gate circuit _{NG4 via the fifth NAND gate circuit NG5 .} and,
After a certain period of time has elapsed, the fourth comparator COM ₄ is inverted, the monostable multivibrator operates, and the second pulse signal oscillator is activated as described above only for a certain period of time determined by the monostable multivibrator.
The low frequency pulse signal "1" from OSC ₂ is applied to one input terminal h of the fourth NAND gate circuit NG ₄ via the sixth NAND gate circuit NG ₆ .

Therefore, the diaphragm member 10 is in a closed state before starting fade-in photography, and operates at high speed when the fade-in start switch SW ₃ is turned off until the aperture value is approximately 4 to 5 steps under from the appropriate exposure aperture value, and then, It operates to the open side at a low speed for a predetermined period of time.

As is clear from the above explanation, according to the aperture control device capable of auto-fading photography according to the present invention, aperture control can be performed at high speed during normal photography, and the aperture control device according to the present invention can perform aperture control at high speed in accordance with the constantly changing subject brightness. The aperture value can always be set to the appropriate exposure aperture value, and the aperture control during auto-fading photography is performed at a low speed in the range between the appropriate exposure aperture value and an aperture value approximately 4 to 5 steps below this aperture value. In addition, in a range below the above range, the fading is performed at a high speed, so that extremely natural fading can be performed.

[Brief explanation of the drawing]

The drawing is a circuit diagram of the main parts of an embodiment of an aperture control device capable of auto-fading photography according to the present invention. 10... Aperture member, 20... Stepping motor drive circuit, OSC ₁ ... First pulse signal oscillator,
OSC ₂ ...Second pulse signal oscillator, SW ₁ ...First
Mode changeover switch, SW ₂ ...Second mode changeover switch, _SW3 ...Fade-in start switch.

Claims (1)

[Scope of Claims] 1. In an aperture control device capable of auto-fading photography, which operates an aperture member using a stepping motor controlled by a pulse signal to perform fading, after the start of fade-out and Pulse signal frequency selection means is provided for reducing the frequency of the pulse signal applied to the stepping motor within a certain period of time after reaching an aperture value that is about 4 to 5 steps under the appropriate exposure aperture value at the time of fade-in. An aperture control device capable of auto-fading photography. 2. The pulse signal generating means for generating pulse signals for controlling the stepping motor is composed of a high frequency pulse signal oscillator and a low frequency pulse signal oscillator, and has an appropriate exposure aperture for a certain period of time after the start of fade-out photography and during fade-in. The stepper motor is configured to be controlled by the pulse signal from the low frequency pulse signal oscillator by the pulse signal frequency selection means for a certain period of time after reaching the aperture value which is about 4 to 5 steps below the aperture value. An aperture control device capable of auto-fading photography according to claim 1. 3. The pulse signal frequency selection means includes a monostable multivibrator, and operates the monostable multivibrator at the start of fade-out and when an aperture value of approximately 4 to 5 steps below the appropriate exposure aperture value is reached during fade-in; Claims characterized in that the stepper motor is configured to operate for a predetermined period of time determined by the monostable multivibrator to cause the stepping motor to be controlled by a pulse signal from a second pulse signal oscillator. An aperture control device capable of auto-fading photography according to scope 2.