JPS6241297Y2 - - Google Patents

Description

[Detailed Description of the Invention] The invention relates to a program exposure control camera. In Japanese Patent Application No. 52-145513, the applicant obtains information on a predetermined program shutter speed by performing TTL photometry and appropriately transforming the photometry signal, and outputs according to this program shutter speed. is compared with the photometric signal during the aperture stop-down after the release operation, and when the two reach a predetermined relationship, the stop-down operation is stopped, and the photometric signal containing information on the determined aperture value is generated. We proposed a program exposure control camera that ultimately controls the shutter speed based on .

In such a device, it is necessary to store the photometric output twice: immediately before the aperture is stopped down, and once after the aperture stops and before the mirror is raised.

The present invention provides a circuit that is configured so that the two times of memorization can be achieved by a single switch that is linked to the aperture control device, thereby preventing the camera mechanism from becoming complicated.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention. Reference numeral 1 denotes a TTL photometry circuit that receives light from an object that has passed through a photographic lens and generates a photometry signal according to the brightness of the object. 2 is photometry circuit 1
A first circuit that generates a first signal corresponding to a predetermined program shutter speed in response to a photometric signal from the shutter speed. 3 is the first circuit from the first circuit 2
This is an aperture control device that automatically adjusts the aperture according to the signal. Reference numeral 4 denotes a shutter control device that automatically controls the shutter speed in accordance with a photometric signal after the aperture adjustment by the aperture control device 3. The photometric signal applied to the shutter control device 4 includes information on the brightness of the subject and the aperture, thereby obtaining information on the adjusted aperture and the shutter speed in accordance with the brightness of the subject. Reference numeral 5 designates a second circuit that generates a second signal corresponding to the shutter speed determined in accordance with information on the controllable limit aperture diameter and subject brightness. Reference numeral 6 denotes a display device for displaying the controlled shutter speed, which can be displayed by a meter or by light emission. 7 is a comparison circuit that changes its state depending on the magnitude of the first signal and the second signal. Reference numeral 8 denotes a selection circuit that selectively applies the first signal or the second signal to the display device depending on the state of the comparison circuit.

210 is a switch means that operates in conjunction with the release operation. Specifically, the switch means 210 is activated by the operation of the aperture control mechanism 3 by the release operation before the aperture adjustment operation. 21
1 is a first holding circuit that holds the first signal by operating the switch means 210; Reference numeral 212 holds a photometry signal from the photometry circuit 1 which has started to photometer the subject light that has passed through the aperture adjusted by the aperture control device 3 after a predetermined time has elapsed since the switch means 210 was activated. This is a second holding circuit. 213 is a delay circuit.

In the initial stage of operation, the photometry circuit 1 performs photometry with the aperture fully open, and this photometry signal is applied to the first circuit 2. The first circuit 2 generates a first signal corresponding to a predetermined program shutter speed in response to the photometric signal, which is applied as one input to the comparator circuit 7. On the other hand, the second circuit 5
generates a second signal corresponding to the shutter speed determined according to information on the controllable limit aperture diameter and subject brightness, and applies this to the comparator circuit 7 as the other input.

In the next step when the shutter button is pressed, the first holding circuit is activated by actuation of the switch means 210 to memorize the first signal. At the same time, delay circuit 213 receives a signal from switch means 210 and starts operating. The diaphragm control device 3 then automatically adjusts the diaphragm according to the first signal stored in the holding circuit. After this aperture adjustment, the second holding circuit 212 receives the output of the delay circuit 213 and holds the photometric signal from the photometric circuit 1. When this stage is completed, the shutter control device 4 automatically controls the shutter speed based on the output of the second holding circuit 212 which has shutter speed information corresponding to the adjusted aperture value. During aperture control, if there is no aperture value to be adjusted because the subject is too bright or too dark, the aperture control device 3 adjusts the aperture to the maximum aperture diameter or the minimum aperture diameter. The shutter speed controlled at this time corresponds to the second signal and is naturally different from the shutter speed corresponding to the first signal.

Therefore, the comparator circuit takes the first signal and the second signal as input, changes its state according to the values thereof, and when the shutter speed controlled by the shutter control device 4 corresponds to the first signal, A first signal is applied to the display device 6 via the selection circuit, and this
, a second signal is applied to the display device 6 via the selection circuit 8.

In this way, the display device always displays the shutter speed that is actually being controlled.

According to the embodiment of the present invention described above, the first holding circuit 211 includes an analog switch that disconnects the photometric signal from the first signal by the operation of the switch means 210, and a disconnection operation of the analog switch. It includes a capacitor that stores at least the photometric signal or the first signal. Also, the second holding circuit 21
Reference numeral 2 denotes an analog switch that disconnects the photometry circuit 1 and the shutter control device 4 after a predetermined period of time has elapsed from the operation of the switch means 210 and the aperture is adjusted by the aperture control device 3, and a disconnection operation of this analog switch. It includes a capacitor for storing the photometric signal from the photometric circuit 1.

Next, an example of the present invention will be described. Figure 2 a~
3c shows a mechanical part, FIGS. 3a and 3b show a shutter speed programming method, and FIGS. 4 and 5 show a circuit part.

First, the mechanical part will be explained.

In FIG. 2a, when the shutter button (not shown) is pressed, the locking pawl 12 moves counterclockwise around the rotating shaft 133 against the spring 144, as 11a and 11b move downward. Claw 16
rotate counterclockwise about the rotation axis 17 against the spring 18. Then, the claw part 12a of the locking claw 12 and the rising part 13 of the aperture operating lever 13
a is disengaged. The aperture operating lever 13 begins to rotate clockwise around the rotating shaft 20 together with the aperture lever 14 due to the spring force of a spring 15 fixed to the aperture lever 14 on the lens side. At its initial stage, mechanical switch S1 is opened. When the lever 13 rotates, the intermediate lever 21 rotates counterclockwise due to the engagement of the pin 13c. The rotation is transmitted to the sector lever 23 via the intermediate shaft 22 (transferring to FIG. 2b). Sector lever 23
A part of is a gear 23a, and its rotation is 2
Gear 2 that meshes with gear 3a and gear 2 that is integral with 26
The speed is increased by gear 28 meshing with gears 7 and 27 and transmitted to ratchet wheel 29. On the other hand, when the locking pawl 16 rotates as described above by pressing the shutter button, the locking portion 16a and the lever 51 are disengaged (moving to FIG.
The force starts to rotate counterclockwise about the shaft 52. A part of the lever 51 is a gear 51b, which meshes with a gear 55. The gear 55 and the gear 56, gear 57, and flywheel 58 integrated therewith constitute a delay mechanism and serve to delay the operating speed of the lever 51. At the initial stage of the operation of the lever 51, the pin 56a implanted in the gear 56 is retracted clockwise, so that the lever 59 is rotated counterclockwise about the shaft 60 by the force of the spring 61. Then, the hold lever 63 rotates clockwise about the shaft 64 by the force of the spring 65, releasing the lever 30 that had been pressed against the electromagnet Mg. However, as will be described later, the power switch S _M is turned on at the initial stage of pressing the shutter button, and the electromagnet M
1 is excited, the iron piece 34 becomes an electromagnet Mg1
, and the lever 30 does not move.

When the aperture lever 14 on the lens side is moved downward by the force of the spring 15, the aperture of the lens is narrowed down from wide open to small aperture by a known mechanism. Due to the operation of the circuit, the electromagnet Mg1 is demagnetized and the iron piece 34 is separated from the electromagnet Mg1.As a result, the lever 30 rotates counterclockwise under the action of the spring 32, and its rising portion 30a is connected to the ratchet wheel 29.
It enters the ratchet pawl and locks it.

(Moving to FIG. 2a) When the lever 51 further rotates counterclockwise, it comes into contact with a portion 101a of the lever 101 near the end of its movement, and the lever 101 is rotated about the shaft 102 against the spring 103. It rotates clockwise and disengages from the lever 104. Then, the lever 104 is rotated clockwise by the action of the spring 105. When the lever 104 further rotates, it pushes up a pin 106 fixed to a mirror holder (not shown) and the mirror rotates upward about a rotation axis 107. As the lever 104 rotates, the pin 104b
The lever 108 rotates counterclockwise about the shaft 109 against the spring 110, and the lever 10
At the end of the rotation of step 4, release lever 11 of the shutter
Press 1 to release the shutter.

When the predetermined exposure time has expired and the trailing curtain of the shutter has finished running, the signal lever 112 of the shutter moves downwards, so that the lever 115 is moved around the axis 116 against the spring 117 via the intermediate lever 113. rotated clockwise. Then lever 11
5 is disengaged from the lever 118, and the lever 119 is rotated clockwise about the shaft 120 by the force of the spring 121. A portion 119a of the lever 119 and a pin 118a fixed to the lever 118 are engaged with each other, and the lever 118 rotates counterclockwise at the same time. At the initial stage of rotation of the lever 119, one end 119b of the lever 119 comes into contact with the lever 63,
This is rotated counterclockwise to disengage the engagement between the rising portion 30a of the lever 30 and the ratchet wheel 29. When the levers 118 and 119 further rotate, the pin 118b fixed to the lever 118 moves to the lever 1.
04 and 13, both levers and lever 1
21, 22, 23, 26, 27, 2 engaged with 3
The series of systems 8 and 29 are returned to the positions shown.
Therefore, the pin 106 is returned by a spring (not shown), so that the mirror is lowered, and the lever 14 is returned to its original position, returning the diaphragm to the open position.

When one photographing operation is completed and the winding lever is operated next, the pin 122 moves clockwise and the levers 119 and 118 return to the illustrated positions.

Next, I will explain the program.

There are two possible programming systems for cameras with interchangeable lenses, such as single-lens reflex cameras, depending on how the difference between the maximum aperture diameter and the minimum aperture diameter of each lens is processed. Figure 3 shows typical examples of this for a lens with an open aperture diameter of F1.4 and a minimum aperture diameter of F16 (hereinafter referred to as lens A) and a lens with an open aperture diameter of F4 and minimum aperture diameter of F32 (hereinafter referred to as lens B). a and b. This program diagram is divided into three parts. As Ev increases, there is a part where the aperture remains at its maximum aperture diameter and only the shutter speed changes (hereinafter referred to as the x part), a part where both the aperture value and shutter speed change (hereinafter referred to as the y part), and the aperture remains at its minimum aperture diameter. There are three parts in which only the shutter speed changes (hereinafter referred to as the z part).

In the method shown in Fig. 3a, the above-mentioned lens A and lens B are
However, in the method shown in FIG. 3B, the y part of the lens B is the y part of the lens A translated in parallel. For each of the following
Let's try to derive the relational expression for the part. For the sake of simplicity, the APEX representation (Av, Tv, Ev, Bv, Sv) is used in the relational expression. From a simple consideration, the formula for the y part in Figure 3a is Tv = 0.75Av + 3.25 = 0.75 (Av - Av ₀ ) + 0.75Av ₀ + 3.25
...(1) However, Av ₀ : Av value of lens open aperture diameter The y part in Figure 3b is Tv = 0.5 (Av - Av ₀ ) + 6 ... (2) Therefore, the general formula for the y part is Tv = α(Av−Av ₀ )+βAv ₀ +γ …(3) Here, α, β, and γ are constants. In the method shown in Figure 3 a, β = α. In the method shown in Figure 3 b, β = 0. Here, the aperture value variable is The reason for using (Av−Av ₀ ) instead of Av is that this method is easier to handle in the case of the TTL method.

Next, by introducing the formula for proper exposure for APEX display, Av+Tv=Bv+Sv, and transforming equation (3), we get Tv=α(Bv+Sv−Tv−Av ₀ )+βAv ₀ +γ Tv=α/1+α(Bv+Sv−Av ₀ ) +1/1+α(βAv ₀ +γ)...(4) The meaning of equation (4) is to calculate the straight line of the y part of the program a or b in Figure 3 for the given subject brightness, film sensitivity, and lens aperture. This is the formula for calculating the shutter speed that meets the conditions for proper exposure.

Next, the circuit portion and operation will be explained.

In FIG. 4, open the program mode switch _S3 to turn it off, and set the aperture ring of the lens to the minimum aperture (F16 for lens A, F32 for lens B). When the shutter button is pressed, in the first step, the power switch S _M is turned on and current is supplied from the power battery E1 to the entire circuit system. At this time, mechanical switch S1 is on, so the inverter
The output of INV is at H level. Also transistor
Since _Q1 is turned on, the output of converter CP is at H level. F ₄ and F ₅ are voltage followers and have an enable terminal (control terminal). When the enable terminal is at H level, the input voltage is directly output to the output terminal, and when the enable terminal is at L level, the output voltage is undefined. It has a characteristic that the output impedance becomes infinite. Therefore,
Since the voltage follower _F4 receives the H level from the inverter INV, and the voltage follower _F5 receives the H level from the converter CP, the input voltage is directly output to the output terminal. Voltage followers act as analog switches, so they can be replaced with transistors, FETs, etc. The photodiode PD receives the light that has passed through the lens and the aperture and generates a photocurrent proportional to its intensity. This photocurrent is then logarithmically compressed by the amplifier OP1 and the diode D1. Constant current source CC1 and diode D
2 is for compensating the temperature characteristics of the diode D1.
At this stage, the levers 12 and 16 have not moved yet, so the lens aperture lever 14 is set to lever 1.
3, the aperture of the lens is opened (the state shown in FIG. 2a). Therefore, the light incident on the photodiode PD is obtained by subtracting the information about the aperture diameter of the lens from the object light, and the value obtained by logarithmically compressing it becomes (Bv - Av ₀ ) in APEX expression. Film sensitivity information is input to the input of amplifier OP1 by variable constant voltage circuit E2.
Since a voltage equivalent to Sv is applied, the amplifier
The voltage V _A (photometric signal when the aperture is open) at the output terminal A point of OP1 is V _A = (Bv + Sv - Av ₀ ) (5). This A point voltage is divided by resistors _R1 and _R2 . Since the resistance ratio of R ₁ and R ₂ is set to be α/1 + α in equation (4), the voltage at the connection point of resistors R ₁ and R ₂ is α/1 + α (Bv + Sv − Av ₀ ). Become.

This corresponds to a shutter speed signal related to shutter speed. This voltage is then applied to the amplifier OP2 via the voltage follower _F4 , where information of 1/1 + α (βAv ₀ +γ) is added to this voltage by the constant current source CC2 and the variable resistor _R3 , and the result is The voltage V _B at the output terminal B of the amplifier OP2 is expressed as V _B =α/1+α(Bv+Sv−Av ₀ )+1/1+α(βAv ₀ +γ) (6), which corresponds to Tv according to equation (4). In the case of the program shown in Figure 3a, it is necessary to configure _R3 so that it changes depending on the aperture diameter of the lens, but in the program shown in Figure 3b, β=0, so _R3 is A fixed resistance corresponding to γ is sufficient. On the other hand, the output voltage of amplifier OP1, that is, the voltage at point A, is applied to the input terminal of amplifier OP3. Here, information of ((Av)preset-Av ₀ ) is subtracted from the aperture value set on the aperture ring, that is, the APEX display, by a constant current source CC3 and a variable resistor _R4 that changes in conjunction with the aperture ring of the lens. In this case, the aperture ring is set to the aperture value of the minimum aperture diameter, that is, Avmin, so the amplifier OP
The voltage Vc at the output terminal C point of No. 3 is (Bv+Sv-Av ₀ )-(Avmin-Av ₀ )=Bv+Sv-Avmin (7).

Comparing equations (5), (6), and (7) with the appropriate exposure equation for APEX display, Av+Tv=Bv+Sv, that is, Tv=Bv+Sv−Av, we find the following. That is, at the initial stage of the release operation, the A point voltage V _A
(photometering signal and second signal) indicates the Tv value (Tv)a of the x part of the program diagram, that is, the Tv value that meets the conditions for proper exposure at the open aperture diameter, and the B point voltage V _B ( 1 signal) is the y part of the program diagram.
It shows the Tv value (Tv)b, and the C point voltage V _C (second signal) is the Tv value that meets the conditions for proper exposure at the minimum aperture diameter, that is, the Tv value (Tv)c at the z part of the program diagram. shows. The voltage V _A is further applied to the comparators CP1 and CP3 via the voltage follower F ₂ and the voltage follower F ₅ , the voltage V _B is applied to the voltage follower ₁ and the comparators CP1 and CP2 , and the voltage V _C is applied to the voltage follower F ₃ and comparator CP2
added to.

Now, if V _B > V _A , (Tv) b >
(Tv) a, but in this state, if you follow the y part of the program curve, the aperture value will be larger than the aperture of the lens, so you will inevitably have to control it according to the x part of the program curve. . At this time, the output of comparator CP1 becomes H level,
Also, since V _C is always smaller than V _A , the comparator
The output of CP2 becomes L level. Therefore, the enable terminal of voltage follower _F1 is the NOR gate G.
The output of F2 sets the _F2 enable terminal to the H level, and the _F3 enable terminal to the L level. Therefore, meter M has F ₂
A voltage V _A is applied via.

Next, when V _A > V _B > V _C , the control follows the y part of the program curve, but at this time comparator CP1
The output of comparator CP2 becomes L level, and the output of comparator CP2 becomes L level. Therefore, the enable terminals of the voltage follower _F1 are set to H level, _F2 to L level, and _F3 to L level. Therefore, voltage V _B is applied to meter M via F ₁ .

When V _A > V _C > V _B , the aperture is narrower than the minimum aperture diameter in the y part of the program curve, so control follows the z part, but in this case, comparator CP1 The comparator CP2 outputs an H level, and the voltage follower enable terminal _F1 is at an L level, _F2 is at an L level, and _F3 is at an H level. Therefore, a voltage V _C is applied to the meter M via the voltage follower F ₃ .

As can be seen from the above, when the exposure control follows the x part of the program diagram, when the voltage V _A follows the y part, and when the voltage V _B follows the z part, the voltage V _C is applied to the meter M, and the fifth point is applied to the meter pointer. By arranging the shutter speed scales to face each other as shown in Figure A, it is possible to always display the correct Tv value at which control is scheduled. Note that this display does not need to be based on a meter, but may be one in which a light emitting diode LED and a shutter speed scale are opposed to each other as shown in FIG. 5b.

Next, press the shutter button further and the lever 1 mentioned above will be activated.
2 and 16 are released, and the lever 14 is
The aperture of the lens is narrowed down by the mid-downward operation, but before that, switch S1 opens and turns off, the output of inverter INV becomes L level, and the output impedance of voltage follower _F4 becomes infinite. The voltage at the connection point between resistors R ₁ and R ₂ is stored in capacitor C1, and voltage V _B is fixed. At the same time, transistor Q ₁ is turned off, and a delay circuit consisting of resistor R _T , capacitor C _T , and comparator CP starts operating. The delay time of this delay circuit is set so that the state of the comparator CP changes and outputs the L level just before the aperture adjustment is completed and the mirror starts to rise. As the aperture is narrowed down over time, the amount of light incident on the photodiode PD will be the value obtained by subtracting the information about the actual aperture at each point in time from the subject brightness, so the output voltage V _A of amplifier OP1 will be (Bv +
Sv−Av), resulting in only a photometric signal. And it represents the Tv value that is suitable for the appropriate exposure conditions corresponding to the aperture information at that time. Voltage V _A and fixed voltage V _B are compared by comparator CP1, and when V _A and V _B match, comparator CP1
The output of 1 becomes H level. Therefore, the current that had been flowing through electromagnet Mg1 is cut off and lever 3
Since the tip 30a of the zero enters the pawl of the ratchet wheel 29 and fixes the narrowing lever 14, the narrowing down operation is stopped. After this, just before the mirror rises, the comparator CP outputs an L level, so the output impedance of the voltage follower _F5 becomes infinite, and the voltage V _A is stored in the capacitor C2. This stored voltage V _A is applied to the comparator CP3.
This is one of the inputs. The mirror rises and lever 1
When the shutter is released by 08, the trigger switch S4 opens when the front shutter curtain starts running, and the amplifier OP4 constant voltage circuit E3 and the capacitor C
3. Diodes D3, D4 and resistor R, constant current source
The time logarithmic conversion circuit composed of CC4 starts operating. This circuit outputs a voltage according to the exposure time Tv value after the shutter front curtain starts running. When this Tv value matches the stored voltage V _A , comparator CP3 is activated and the electromagnet
Mg2 is demagnetized and the trailing curtain starts running.

Note that when the switch S3 is closed and turned off, the aperture priority mode is set. Then, the light emitting diode LD lights up to indicate that it is in aperture priority mode, and current flows through resistors R ₆ and R ₇ and transistor Q ₂
turns on.

Then, voltage V _B is forced to the ground level. Resistor R ₄ introduces the information of the manually set aperture preset value ((Av) preset - Av ₀ ), so the value of voltage V _C becomes Bv + Sv - (Av) preset, which corresponds to the set aperture value. This will show the Tv value suitable for proper exposure. On the other hand, since the voltage V _B is smaller than the voltage V _C as described above, V _C is applied to the meter M by the operation described above. When controlling
Since the output of CP1 always remains at the L level, the aperture is not locked until it reaches the value set by the lens preset ring. When the aperture reaches the set value, the shutter is controlled by the voltage V _A as described above.

In the embodiments described above, if the aperture ring is accidentally set to a value other than the minimum aperture diameter in the program mode or shutter priority mode, it will be impossible to control the aperture smaller than the set aperture diameter. Become. In that case, control is performed as if the aperture value set by the aperture ring was the minimum aperture diameter, but even in that case, by introducing the set aperture diameter into the circuit through resistor _R4 , the shutter can be controlled correctly. It is possible to display the speed.

In the embodiment described above, the elements OP1, PD, E2, D
1, D2, CC1 is the TTL photometer, element R1,
R2 is a shutter speed signal generation circuit that generates a shutter speed signal related to the shutter speed, and element S
1 is the mechanical switch means, element F4 is the first analog switch, element C1 is the first capacitor, elements CP1 and Mg1 are the aperture control device, element
RT, CT, and CP constitute a delay circuit, element F5 constitutes a second analog switch, element C2 constitutes a second capacitor, and elements CP3 and Mg2 constitute a shutter control device.

As described above, according to the present invention, the capacitor C
1. Two memory operations by C2 are performed by switch S1.
The camera's mechanism does not become complicated because the operation of the camera is used as a trigger and the subsequent operations are controlled electrically.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of a program exposure control camera according to the present invention, Fig. 2a,
2b and 2c are diagrams showing some mechanisms of the aperture control circuit 3 and shutter control device 4 in FIG. 1, and FIGS. 3a and 3b are program diagrams showing the shutter speed program. 4 is a circuit diagram specifically showing the circuit configuration in place of the block diagram of FIG. 1, and FIGS. 5a and 5b are diagrams showing the display form of an indicator showing the shutter speed. Explanation of symbols of main parts, TTL photometry circuit...
1. First circuit... 2. Aperture control circuit... 3. Shutter control circuit... 4. Second circuit... 5. Shutter speed display device... 6. Comparison circuit... 7. Selection circuit... 8. Switch means...210, first holding circuit...211, second holding circuit...212,
Delay circuit...213.

Claims (1)

[Scope of utility model registration request] A TTL photometer that generates a photometric signal according to the subject light that has passed through the aperture of the lens; a shutter speed that generates a shutter speed signal related to the shutter speed according to a predetermined program from the photometering signal when the aperture is open a signal generating circuit; a mechanical switch means that operates in conjunction with the release operation; a first analog switch that normally transmits a shutter speed signal and cuts off transmission of the shutter speed signal in response to the operation of the switch means; a first capacitor that receives a shutter speed signal through an analog switch, and holds the shutter speed signal by cutting off transmission of the shutter speed signal; the shutter speed signal held in the first capacitor; an aperture control device that stops the aperture and adjusts the aperture when the photometric signal, which changes in response to the aperture operation performed in conjunction with the release operation, reaches a predetermined relationship; A delay circuit that generates an output signal when a predetermined time required for aperture adjustment by the aperture control device has elapsed; usually a delay circuit that transmits a photometric signal to the aperture control device and cuts off transmission of the photometric signal by the output signal of the delay circuit. 2 analog switch;
a second capacitor that receives a photometric signal through the analog switch and holds the photometric signal after the aperture is adjusted by the aperture control device by the second analog switch cutting off transmission of the photometric signal; and a shutter control device that adjusts a shutter speed in accordance with the photometric signal held by the second capacitor.