JPS6227368B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic exposure amount control device capable of auto-fading, and more particularly to an automatic exposure amount control device in which an aperture member that performs exposure control is driven by a stepping motor. It is something.

Already, the brightness of the subject is measured by a photometry circuit including a photoreceptor, and a driving means called a stepping motor or pulse motor (hereinafter referred to as a stepping motor) is operated based on the photometry information. 2. Description of the Related Art An automatic exposure amount control device in which a diaphragm member for controlling the exposure amount is driven by a driving means has been proposed and is well known.

Further, in the automatic exposure amount control device having the above configuration, the stepping motor is forcibly operated to drive the aperture member from the appropriate exposure aperture value to the close side to perform auto fade-out, and from the closed state to the appropriate exposure. An automatic exposure amount control device capable of auto-fading has also been proposed, which can perform auto-fade-in by driving the aperture to the maximum aperture value.

By the way, since the above-mentioned stepping motor is operated at a speed that depends on the frequency of the pulse signal that controls its operation, in the case of an automatic exposure amount control device, its operation is controlled by a high-frequency pulse signal. If this is not done, it will not be possible to control the exposure amount in accordance with the ever-changing subject brightness. However, in contrast, fading requires driving the aperture member over a certain length of time, and in this case, the stepping motor may be controlled by a low-frequency pulse signal. It is desired. In addition, fading should be approximately 4mm from the appropriate exposure aperture value unless there is a high-brightness object that is noticeably different from others in the subject.
Substantial fade-out is completed by stopping the aperture down to about 4 to 5 steps under from the appropriate exposure aperture value, and substantial fade-in is completed by opening the aperture to the appropriate exposure aperture value from about 4 to 5 steps under the appropriate exposure aperture value. I can say that. Therefore, during fading, it is desirable that the aperture member operate at least at a low speed between the appropriate exposure aperture value and an aperture value that is approximately 4 to 5 steps under the appropriate exposure aperture value.

In view of the above, the present invention provides an improved automatic exposure amount control device capable of auto-fading.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic exposure amount control device capable of auto-fading according to the present invention will be described in detail below with reference to the accompanying drawings.

The drawing is a circuit diagram of a main part of an embodiment of an automatic exposure amount control device capable of auto-fading according to the present invention. Reference numeral 10 indicates an exposure amount control aperture member, and the object light passing through the aperture member 10 is A photoreceptor RX, such as a CDS, is placed at a position where it can receive light. This photoreceptor RX is connected to a photometric bridge connected to a power source E via a main switch _SW0 , along with a variable resistor Rν set based on the photosensitivity of the film used, and first to third resistors _R1 to _R3 . This bridge circuit connects first and second comparators COM1 and _COM1 based on changes in subject brightness.
Apply an unbalanced output signal to COM ₂ . The output terminals of the first and second comparators COM ₁ and COM ₂ are connected to pull-up resistors R ₄ and R ₅ and are connected to one of the first and second NAND gate circuits NG ₁ and NG ₂ , respectively, which constitute a flip-flop circuit. Connected to input terminals a and c. Further, the output terminals of the first and second NAND gate circuits NG ₁ and NG ₂ are connected to the third and fourth NAND gate circuits NG ₃ through the first and second inverters INV ₁ and INV ₂ , respectively.
and one input terminal e and g of NG ₄ . Furthermore, the third and fourth NAND gate circuits
The other input terminals f and h of NG ₃ and NG ₄ are connected to the output terminals of fifth and sixth NAND gate circuits NG ₅ and NG ₆ provided as described later, and those output terminals are connected to the output terminals of the stepping motor. L ₁ to L ₄
It is connected to a stepping motor drive circuit 20 which excites a drive coil represented by , so as to control its operation. The fifth and sixth NAND gate circuits NG ₅ and NG ₆ each have one input terminal i and k of the first gate circuit, each of which oscillates a low frequency pulse signal.
A third pulse signal oscillator connected in series is connected to a pulse signal oscillator OSC ₁ and a second pulse signal oscillator OSC ₂ that oscillates a high frequency pulse signal, and the other input terminals j and l are connected to a third pulse signal oscillator connected in series whose operation is controlled as described later.
and a fourth inverter INV ₃ and INV ₄ connected to their respective output terminals. The fourth inverter INV ₄ is connected to the output terminal of a monostable multivibrator consisting of transistors Tr ₁ and Tr ₂ , a capacitor C ₁ and resistors R ₆ to R ₉ , and when this monostable multivibrator is in an operating state. A signal of "1" is sometimes input for a certain period of time determined thereby. This monostable multivibrator is controlled by a fade-out/fade-in setting circuit, which will be explained next, through the first and second mode changeover switches _SW1 and _SW2 , which _are switched simultaneously by one operating member. It is configured to be motion controlled.

The first and second mode changeover switches _SW1 and
SW ₂ is a switch that is switched in conjunction with the operation member (not shown), and is a first mode changeover switch.
SW ₁ is the output terminal of the first NAND gate circuit NG ₁ and the input terminal d of the second NAND gate circuit NG ₂ when the operating member is in the normal photographing position of the neutral position.
When the movable contact piece A connected to is connected to the open terminal B and the operating member is rotated counterclockwise to the fade-out shooting position, the movable contact piece A is connected to the grounded fixed terminal C, and When the operating member is rotated clockwise to the fade-in photographing position, the movable contact piece A is connected to a fixed terminal D connected to an output terminal of a seventh NAND gate circuit _NG7 , which will be described later. . Furthermore, when the operating member is in the normal photographing position, the second mode changeover switch SW ₂ connects the movable contact piece H connected to the trigger capacitor C ₂ of the monostable multivibrator to the open terminal, and the operating member When the operating member is in the fade-out photographing position, the movable contact piece H is connected to a grounded fixed terminal G, and when the operating member is in the fade-in photographing position, the movable contact piece H is connected to a seventh inverter described later.
It is configured to be connected to a fixed terminal connected to the output terminal of INV ₇ .

Further, in the drawings, NG ₈ and NG ₉ indicate the eighth and ninth NAND gate circuits constituting the flip-flop circuit, and one input terminal m and o of each are connected to the fade-in setting switch SW ₃ and the close holding switch SW ₄ . It is provided to be grounded through the ground. The fade-in setting switch SW ₃ is linked to the shutter release operation, and is turned on along with the main switch SW ₀ by the first step operation of the shutter release operation, and turned off by the second step operation. A close holding switch SW ₄ is provided so as to be turned on when the aperture member 10 performs a narrowing operation and enters a closed state. Said fade-in setting switch
SW ₃ is further connected to the other input terminal of the tenth NAND gate circuit NG _{10 whose one input terminal is the output terminal of the eighth NAND gate circuit NG 8 ,} and is connected to fifth and sixth inverters INV 5 and ₅ connected in series.
It is also connected to the input terminal of the fifth inverter INV ₅ of INV ₆ . Furthermore, the 10th NAND gate circuit NG ₁₀
is a switching transistor whose output terminal is
Connected to the base terminal of Tr ₃ . A storage capacitor C ₀ is connected to the collector terminal of the switching transistor Tr ₃ and the positive input terminal of the third comparator COM ₃ .
Timing switch _SW5 is connected in parallel with _C0 . The timing switch _SW5 is a normally closed switch that is turned off at the start of the photographing operation.

A reference voltage determined by resistors R' and R'' is applied to the negative input terminal of the third comparator COM ₃ , and this is determined by the time required to take a certain number of steps, for example 4 to 5 steps, from the proper exposure aperture value. is set to correspond to

Further, the seventh NAND gate circuit NG ₇ has one input terminal connected to the fade-in setting switch.
SW ₃ , the other input terminal is the timing switch
The _seventh inverter INV ₇ has an input terminal connected to a NOR circuit, that is, an output terminal of the third comparator COM ₃ , and
It is connected to the output terminal of a NOR circuit NOR having an input terminal grounded via the timing switch _SW5 .

The automatic exposure control device configured as described above operates as follows during normal photography, fade-out photography, and fade-in photography.

First, in normal photography, this automatic exposure amount control device places the photography mode switching operation member in the neutral position, and turns the movable contacts A and H of the first mode switching switch _SW1 and the second mode switching switch _SW2 , respectively. By connecting open terminals RO and F, so-called
EE works. In other words, if the amount of light is now greater than the appropriate exposure aperture value, this automatic exposure amount control device will cause the balance of the photometric bridge circuit to collapse and the output of the first comparator COM ₁ to be "1" and the output of the second comparator COM ₂ to be "1". 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 first inverter
The output of INV ₁ is "1", the output of the second inverter INV ₂ is "0", the output of the fourth inverter INV ₄ is "1", and the output of the third inverter INV ₃ is "0".
Therefore, receiving the signal from the high frequency second pulse signal oscillator OSC ₂ via the fifth NAND gate circuit NG ₅ , the input of the third NAND gate circuit NG ₃ becomes "1,
1'', the output becomes 0, and the stepping motor drive circuit 20 drives the aperture member 10 toward the close side. Also, if the light amount is insufficient than the appropriate exposure aperture value, this automatic exposure amount control device will output ``0'' from the first comparator COM <sub>1</sub> , ``1'' from the second comparator COM ₂ , and NG from the first NAND gate circuit. The output of _the second NAND gate circuit NG ₂ is "0", the output of the first inverter INV ₁ is "0", and the output of the second inverter INV ₂ is "1".
Therefore, the input of the fourth NAND gate circuit NG ₄ becomes "1, 1" and the output becomes "0", and the stepping motor drive circuit 20 drives the aperture member 10 to the open side.

Next, the operation of this automatic exposure amount control device during fade-out photography will be explained. This automatic exposure amount control device rotates the operating member counterclockwise to bring it to the fade-out photography position, and thereby the aperture member 10 is adjusted. It moves toward the close side and gradually reduces the amount of light, creating a fade-out. That is, the normal shooting is then switched to the fade-out shooting, and the output of the first NAND gate circuit _NG1 is grounded to "0" through the first mode changeover switch _SW1 , and the output is set to "0" through the second mode changeover switch _SW2 . When the capacitor _C2 is grounded, the monostable multivibrator becomes operational, and the input of the fourth inverter _INV4 becomes "1" for a certain period of time determined by this monostable multivibrator. , becomes "0" after a certain period of time has elapsed. Therefore, in this automatic exposure amount control device, after setting the fade-out shooting, the third NAND gate circuit NG3 is connected to the input of the fifth NAND gate circuit _NG3 at the same time as the fade-out shooting position.
A signal from the low frequency first pulse signal oscillator OSC ₁ is received via the NAND gate circuit NG ₅ , and the output signal “1,
1'', the aperture member 10 is driven toward the closing side at low speed by the stepping motor drive circuit 20, and after a certain period of time, one input terminal f of the third NAND gate circuit NG ₃ is connected to the sixth NAND gate circuit NG _6. Via the high frequency pulse signal oscillator OSC ₂
The diaphragm member 10 is driven at a high speed by inputting a pulse signal.

Therefore, when performing fade-out photography, this automatic exposure amount control device operates the aperture member 10 at low speed for a certain period of time after the start of fade-out photography, and then operates at high speed to gradually reduce the amount of incident light and achieve fade-out. let The above-mentioned fixed time is preferably set to be the time required to reduce the aperture value from the appropriate exposure aperture value to an aperture value approximately 4 to 5 steps under.

Next, the operation of this automatic exposure amount control device in fade-in photography, which is a feature of the present invention, will be described below.

When performing fade-in photography using this automatic exposure control device, prior to fade-in photography,
The operating member is set to the clockwise fade-in photographing position, the first mode changeover switch _SW1 is set so that its movable contact A is connected to the fixed terminal D, and the second mode changeover switch _SW2 is set so that its movable contact A is connected to the fixed terminal D. After setting the terminal so that it connects to the fixed terminal, operate the shutter release button (not shown).

This automatic exposure control device set as described above turns on the main switch SW ₀ and the fade-in setting switch SW ₃ by operating the shutter release button in the first step, and performs exactly the same operation as during normal shooting. do. In other words, this is because the fade-in setting switch SW ₃ is on, and the close holding switch SW ₄ and timing switch SW ₅ are off, so the outputs of the 8th NAND gate circuit NG ₈ and the 10th NAND gate circuit NG ₁₀ are respectively "1", switching transistor
Tr ₃ is off, the output of the third comparator COM ₃ is "0", the output of the NOR circuit NOR is "0", the output of the fifth inverter INV ₅ is "1", and the monostable multivibrator is inactive, and the above As described above, the diaphragm member 10 reaches the proper exposure aperture value state at high speed. Furthermore, when the shutter release button is operated, the fade-in setting switch SW ₃ is turned off, and this automatic exposure amount control device is activated by the 8th NAND gate circuit.
The output of NG ₈ is "1", the 10th NAND gate circuit NG ₁₀
The output of the transistor Tr ₃ is turned on, the storage capacitor C ₀ is charged, and the seventh
Since the output of the inverter INV ₇ is "1" and the monostable multivibrator is inactive, and the output of the seventh NAND gate circuit NG ₇ is "0", the aperture member 10 is operated at high speed until it is closed. In this automatic exposure amount control device, when the diaphragm member 10 is in the closed state, the close holding switch SW ₄ is turned on, the output of the eighth NAND gate circuit NG ₈ is "0", and the switching transistor Tr ₃ is also turned off. Charging of capacitor C ₀ is stopped. When the timing switch _SW5 is turned on by the subsequent shutter release operation, the charge stored in the memory capacitor _C0 starts discharging through the resistor _R0 , and the terminal voltage of this capacitor _C0 is applied to the third comparator. When the reference voltage of COM ₃ becomes lower than the reference voltage determined by resistors R' and R'', the output of the third comparator COM ₃ is inverted from "1" to "0". Therefore, the output of the NOR circuit NOR is "1", and the seventh inverter INV ₇
The output of is "0". Therefore, in this automatic exposure amount control device, after the timing switch SW ₅ is turned on, the diaphragm member 10 is driven to the open side at high speed, the output of the fifth inverter INV ₅ is reversed to "0", and the monostable multi-function When the vibrator is activated, the diaphragm member 10 is driven toward the open side at a low speed for a certain period of time determined by the monostable multivibrator, thereby achieving a proper exposure aperture value.

Therefore, the operation of this automatic exposure amount control device in fade-in photography is such that the first and second mode changeover switches _SW1 and
By operating the first shutter release after setting SW ₂ , the so-called EE in normal shooting can be set.
make an action. Thereafter, by operating the second stage of the shutter release, the diaphragm member 10 is driven at high speed until it closes, and the timing switch is turned on during the actual shooting operation, thereby closing the memory capacitor C ₀ and the resistor R. The diaphragm member ₁₀ is driven to the open side at high speed for a predetermined time determined by It operates to drive the aperture member 10.

As is clear from the above explanation of the operation, the automatic exposure amount control device capable of auto-fading according to the present invention reduces the time (t ₂ ) required to narrow down the exposure from the proper exposure aperture value state to the closed state in fade-in photography. Compare the memorized time (t ₁ ) required from the proper exposure aperture value state to a certain number of steps, and calculate the time (t ₂ ) at the start of fade-in shooting.
Ideal fade-in photography is performed by operating at a high speed for one hour (t ₁ ) and then gradually increasing the exposure amount at a low speed thereafter.

[Brief explanation of the drawing]

The drawing is a main circuit diagram of an embodiment of an automatic exposure amount control device capable of auto-fading according to the present invention. 10...First pulse signal oscillator, OSC ₂ ...Second pulse signal oscillator, SW ₁ ...First mode selection switch, SW ₂ ...Second mode selection switch, SW ₃
...Fade-in setting switch, SW ₄ ...Closed holding switch, SW ₅ ...Timing switch, C ₀ ...Memory capacitor, COM ₃ ...Third comparator.

Claims (1)

[Claims] 1. Automatic exposure amount control that drives an aperture member having a stepping motor that is operated according to the brightness of the subject to obtain an appropriate exposure aperture value, and also forcibly operates the stepping motor to enable auto-fading. In the apparatus, a narrowing means performs a narrowing down operation at high speed from an appropriate exposure aperture value state to a closed state, a storage means for storing the time required until the narrowing down is performed by the narrowing down means, and a memory stored by the storage means. Comparison means for comparing the time required to reach the aperture value of a certain number of steps from the appropriate exposure aperture value state, and a speed changeover means for switching the stepping motor from high speed to low speed after the start of fade-in photography using the comparison means. An automatic exposure amount control device capable of auto-fading, characterized in that it comprises means.