JPS63291044A - Timing control circuit for program shutter - Google Patents

Abstract

PURPOSE:To reduce the number of mounting parts by charging and discharging a capacitor between the upper limited value of level and the lower limited value of level and making the switching timing of the charge and discharge correspond to the progress of a photographing sequence. CONSTITUTION:The first charging cycle of the capacitor 11 is executed by a current which flows in a constant-current source I1 and the first discharging cycle of it is executed by a current which flows in a constant-current source I2, then the charging and discharging cycles after that are executed by currents which flow constant-current sources I3 and I4 respectively. And timings for actuating current switches S1-S4 connected to the constant-current sources I1-I4 are sequentially switched according to the progress of the photographing sequence. The current switches S1-S4 make as the control inputs become H levels respectively. By using a time constant circuit as a time sequence, the number of time constant circuits is reduced and the high efficiency of mounting space, the reduction of the number of parts and the improvement of reliability can be enhanced in a shutter control circuit.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention provides a timing I! predictive control method for a program shutter using shutter blades that also serve as aperture blades. 1
More details regarding the Jal1 circuit This is a program shutter that improves the efficiency of the mounting space by reducing the number of time constant circuits that increase the mounting space in a 5-circuit configuration by using the 5 time constant circuits in time sequence. The present invention relates to a timing control circuit. 2. Description of the Related Art A timing control circuit for a program shutter using a predictive control method opens a shutter blade with stable characteristics and controls various timings using a seven-time constant circuit. For example, FIG. 6 shows the aperture characteristics of a program shank using Nyasota blades that also serve as aperture blades, where the horizontal axis represents time and the vertical axis represents aperture diameter. Also, to is shirt release timing, tl is auto trigger timing, +3 is tomball timing 1t
, is the timing when the D diameter value becomes +4, for example, and the time from to to +3 after the shutter release until the pinball becomes a pinball is the portion where the shutter blades overlap. Now, if we consider as an example the case where the exposure operation ends when the O diameter value reaches +4 in automatic exposure shooting without using a strobe, the shutter blade actually closes after the member for closing the glossy blade phase is reset. Until the closing operation is examined, there is a so-called mechanical delay due to the inertia of the mechanism members, and therefore 1
It is necessary to release the member for closing the shutter blade at timing t4, which is earlier than timing t5 when the aperture value becomes +4 by an amount corresponding to this mechanical delay time. Therefore, the exposure end timing must be measured starting from timing t2, which is equal to -1- mechanical delay time, before pinball timing t3. Therefore, in automatic exposure shooting without using a flash, (
1) The auto trigger timing also includes a time constant circuit for measuring the time from start timing t2 of exposure calculation to start timing t2 of exposure calculation (hereinafter abbreviated as AE delay time); and (2) a time constant circuit that is activated at start timing t2 of exposure calculation. A time constant circuit is required to measure the exposure end time. Also, if we consider as an example the case where the strobe fires when the 1 aperture value becomes +4 in so-called flashmatic photography using a strobe, the strobe is a cyrisk trigger as is well known, and the mechanical delay described above must be taken into account. Since there is no need to do this, it is sufficient to synchronize the strobe at the timing t5 when the 3rd caliber value actually becomes +4, and therefore it is sufficient to start the predictive calculation of the 2nd caliber value at the actual pinhole timing t3. Therefore, in flashmatic photography using a strobe, (1) auto trigger timing 1. (2) a time constant circuit for measuring the time from to pinhole timing t3 (hereinafter referred to as FM delay time); and (2) a time constant circuit activated at pinhole timing t3 to measure strobe tuning time. is required. As described above, in a camera equipped with a program control system, four two-time constant circuits are required when assuming an automatic exposure mode that does not use a strobe and a so-called flashmatic mode that uses a strobe.

[Problems to be solved by the invention]

By the way, most of the electronic components for cameras in recent years have been integrated into ICs, but generally the time constant circuit is externally attached and built into the circuit.9 As the number of time constant circuits increases, the number of circuit components increases. The number of points increases, which increases problems such as increased manufacturing costs, increased mounting space, and decreased reliability.

[Means to solve the problem]

The present invention has been made in view of these problems.1
By sharing the time constant circuits in time sequence, the number of time constant circuits which increases the mounting space in a two-circuit configuration is reduced, and the shutter control circuit becomes more efficient in mounting space.2 The number of parts is reduced and reliability is improved. The purpose is to achieve this goal. In order to achieve such an object, a timing control circuit for a program shutter according to the present invention has the following means. First, the program shutter timing control device of the present invention has +1.1. The shack blades that also serve as aperture blades are opened to obtain a predetermined aperture characteristic, and
A time constant circuit including a capacitor is operated using a time when the shutter blade operates to a predetermined position before becoming a pinhole as a starting point. The present invention is based on a program shutter timing control device designed to control the timing of automatic exposure photography and the timing of photography using a strobe. (2) A constant current source for charging and a constant current source for discharging are each connected to the capacitor constituting the time constant circuit via a current switch. (3) By the switching operation of this current switch, the capacitor is charged and discharged between a lower level limit value and a lower level limit value. (4) A storage means is provided for storing the switching operation of the current switch in time sequence. (5) The timing of automatic exposure photography and the timing of photography using a strobe are controlled at the switching timing of the output of the storage means.

[Effect]

In the program shutter timing control device of the present invention, the capacitor constituting the time constant circuit is charged by the constant current source for charging until the lower level limit is reached, and when the lower level limit is reached, the capacitor is charged by the constant current source for discharging until the lower level limit is reached. It is discharged by the current source, and therefore performs an oscillating operation by repeating charging and discharging between the upper level limit value and the lower level limit value. This oscillation period can be adjusted by adjusting the level upper limit value and the level lower limit value, or by adjusting the current value of a constant current source for charging and discharging. Then, by adjusting the level upper limit value, level lower limit value, or current value of the constant current source for charging and discharging so that the timing of switching between charging and discharging corresponds to the progress of the shooting sequence,
Various timings can be controlled by switching between charging and discharging, and a single capacitor time constant circuit can be used as a time constant circuit for many timing controls.

【Example】

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a mechanical diagram showing an example of a program shutter to which an embodiment of the present invention is applied, and particularly shows the opening/closing mechanism of the shutter blade. 1 is a shutter base plate, 2 and 3 are shutter blades that also serve as aperture blades, and 4 is a blade opening/closing lever. The shutter blades 2 and 3 are swingably supported on the surface of the shutter base plate 1 by a shaft 1a on the shutter base plate 1, and the two-blade opening/closing lever 4 is also swingably supported on the back surface of the shutter base plate 1 by a shaft 1b on the shutter base plate 1. is supported by A long hole 2a is bored in the shutter blade 2, and a boss 4 provided at the tip of the blade opening/closing lever 4 is inserted into the long hole 2a.
a penetrates through the elongated hole 1c of the shutter base plate 1 and engages with it. Similarly, a long hole 3 is bored in the shutter blade 3. A boss 4b provided at the center of the blade opening/closing lever 4 passes through the elongated hole 1d of the shutter base plate 1 and is engaged with the elongated hole 3a. The one-blade opening/closing lever 4 is subjected to a counterclockwise rotation force by the spring 5, but in the shutter set state (shape M shown in the figure), it is locked by a locking member (not shown) and its left rotation is restricted. Now, 1. When the blade opening/closing lever 4 is released from the lock in conjunction with the stroke of the shutter button (not shown). The blade opening/closing lever 4 is rotated to the left by a spring 5. During this counterclockwise rotation process, the boss 4a rotates the shutter blade 2 to the left about the shaft 1a, and while the blade opening/closing lever 4 rotates to the left, the boss 4b rotates the shutter blade 3 to the right about the shaft 1a. Therefore, the aperture 1e is opened by the shutter blades 2 and 3, and its opening diameter increases. Note that a known speed regulating mechanism such as a governor may be interposed between the spring 5 and the blade opening/closing lever 4 to stabilize the movement of the shutter blade. Further, when the exposure is completed, if the blade opening/closing lever 4 is returned to the initial position by the reverse operation to the above, the shutter blades 2 and 3 are also returned to the initial position, and the exposure operation is completed. Further, 24 is a trigger inch for the normally closed screw 1 which is fixed to the back surface of the shutter base plate 1 so as to be opened and closed by the blade opening/closing lever 4, and in the process of turning the blade opening/closing lever 4 to the left, the aperture 1e becomes a pinhole. It is configured to break when the blade opening/closing lever 4 turns left by a predetermined amount. Next, FIG. 2 is a circuit diagram showing one embodiment of a shutter control circuit for controlling the program shutter of the mechanism as described above. In FIG. 2, 10 is a constant current light/discharge type oscillation circuit;
20 is a sequence control circuit, and 30 is an exposure control circuit. First, 1 oscillation circuit 10 is a capacitor 1 that performs charging/discharging operation.
The terminal voltage of 1 is set to the reference voltage Vr by comparators C1 and C2.
Flip-flop FF compared to efl・V ref2
Set/reset I 2 Free Knob Flop FFI
The charging/discharging of the capacitor 11 is switched by the output of the FFI, and therefore a pulse output can be obtained from the free-knob flop FFI. The capacitor 11 connects (a time constant circuit for measuring IIAE delay time, a time constant circuit for measuring +21FM delay time, and (3) a time constant circuit for measuring strobe tuning time) according to the passage of time. Capacitor 1 has current #1 as a constant current source for charging.
1.I3 is a current source I2.I4 as a constant current source for discharging.
are connected via current switches S1, S2, SS, and S4, respectively). The terminal voltage of capacitor 11 is determined by comparators C1 and C2.
is applied to the negative phase input of comparator C1.
The reference voltage Vrefl is applied to the positive phase input of . A reference voltage V ref2, which is higher than the reference voltage Vrefl, is applied to the positive phase input of the comparator C2. The output of the comparator C1 is the flip-flop F
The output of the comparator C2 is connected to the cent terminal of the flip-flop FFI via the impark 12. Therefore, when capacitor 11 is charged and its terminal voltage exceeds reference voltage Vref2, comparator C2
The falling edge of the output of is inverted by the impark 12 to set the flip-flop FFI, and the capacitor ]1 is discharged so that its terminal voltage becomes the reference voltage Vref.
When falling below l, the rising edge of the output of comparator C1 resets flip-flop FFI. As mentioned above, the capacitor 11 serves as three types of time constant circuits: (1) it acts as a time constant circuit for measuring the AE delay time in the first charging cycle; It acts as a time constant circuit to measure the FM delay time in the first discharge cycle following the first charge cycle, and (3) measures the strobe tuning time in the charge/discharge cycles after the first discharge cycle. It acts as a time constant circuit for The first charging cycle is caused by the current flowing through the constant current source 11, and the first discharging cycle is caused by the current flowing through the constant current source I.
The subsequent charge/discharge cycles are performed by the currents flowing through the constant current sources fX11, I2, and I4.
3. Current switch 5l-32.SS connected to I4.
The operation timing of S4 is sequentially switched as the photographing sequence progresses. These current switches S1, S2, SS, and S4 each have their control inputs set to H.
It is designed to be metered by reaching the level. Next, elements of the sequence circuit 20 that sequentially switches the operation of these current switches S1, S2, SS, and S4 as the photographing sequence progresses will be explained. First, SS denotes a release switch for metering in conjunction with a shutter button (not shown), and 24 denotes a trigger switch shown in FIG. 1. The ground terminal of the release switch SS and the power supply terminal of the trigger switch 24 are connected to an AND gate G1, and the output of the AND gate G1 is applied to the set input of the flip-flop FF2. This flip-flop FF2 is used to remember that the exposure control operation has started, and setting the flip-flop FF2 means that the next stage flip-flop F
This is a condition for setting the flip-flops after F3. The Q output of FF2 is applied to AND gate G2, the Q output of flip-flop FFI is applied to the other input of AND gate G2, and the output of AND gate G2 is the set input of flip-flop FF3. has been added to. Therefore, when the flip-flop FF1 is charged due to completion of the first charging of the capacitor 11 after the flip-flop FF2 is set, the flip-flop FF3 is set. Further, the ζ output of the flip-flop FF2 is connected to the base of the switch notching transistor TRI, and the capacitor 11 can be charged by setting the flip-flop FF2. Next, the flip-flop FF3 is used to remember that the AE delay time has ended, and when the flip-flop FF3 is sent, the next stage flip-flop F
This is a condition for flip-flow knobs after F4 to be sent. The output of the flip-flop FF3 is added to the AND gate G3, the ζ output of the flip-flop FFI is added to the other input of the AND gate G3, and the output of the AND gate G3 is added to the cent input of the free knob flop FF4. It is being Therefore, after the flip-flop FF3 is connected, when the flip-flop FFI is reset due to completion of the first discharge of the capacitor 11, the 5-flip-flop FF4 is connected. Also, the output of flip-flop FF3 is current switch S.
1 control input, and also the free knob flop FF
The output of No. 3 is sent to the current switch S via the AND gate G4.
It is added to the control input of 2, and the flip-flop FF
The current switch S1 is cut off and the current switch S2 is made conductive by the third node at the same time. Further, the output of the flip-flop FF3 is given to an exposure control circuit 30, which will be described later, and serves as a starting point for the exposure control operation. Next, the flip-flop FF4 is used to remember that the FM delay time has ended, and the fact that the flip-flop FF4 is turned on is a condition for the next stage flip-flop FF5 to be turned on. Become. The output of the flip-flop FF4 is applied to an AND gate G5, and the output of the coincidence detection circuit 21 is applied to the other input of the AND gate G5. The output of AND gate G5 is applied to the set input of flip-flop FF5. Therefore, after the flip-flop FF4 is set, the flip-flop FF5 is set when the minus number output circuit 21 generates a coincidence detection signal. The minus number output circuit 21 generates a coincidence detection signal when the counted value of the down edge trigger counter 22 matches the film sensitivity input from the film sensitivity input circuit 23. Also, the ζ output of flip-flop FF4 is an AND gate G
4 to the control input of the current switch S2, and the current switch S2 is cut off by setting the flip-flop FF4. Furthermore, the output of the flip-flop FF4 is applied to AND gates G7 and G8 via an AND gate G6. The output of the flip-flop FFI is applied to the other input of the AND gate G7, the ζ output of the flip-flop FF1 is applied to the other input of the AND gate G8, and the output of the AND gate G7 is applied to the current switch S4. The outputs of G8 are each applied to a current switch S3. Therefore, after the flip-flop FF4 is set, the capacitor 11 is charged and the flip-flop FFI is set.
When the current switch S4 is turned on, the capacitor 11 is discharged, and when the flip-flop FFI is reset by the discharge of the capacitor 11, the current switch S3 is turned on and the capacitor 11 is charged. The capacitor 11 will be repeatedly charged and discharged. Also, the output of flip-flop FF4 is AND gate G
9 has been added. The output of the flip-flop FFI is added to the other input of the AND gate G9, and the output of the AND gate G9 is applied to the counter 22 of the down edge trigger.
Since the counter 22 is added to the count-up input of the flip-flop FF4 after the flip-flop FF4 is set (that is, after the FM delay time ends)
The number of recents of F1 will be counted. As described above, the free knob flop FF5 is set by the coincidence detection signal generated by the coincidence detection circuit 21 at the timing when the count output of the counter 22 coincides with the output of the film sensitivity input circuit 23. The Q output of this flip-flop FF5 is the known strobe light emitting circuit 4.
added to 0. Next, the exposure control circuit 30 will be explained. The exposure control circuit 30 has a capacitor 31 serving as a time constant circuit and a constant current source 5 that charges the capacitor 31. The constant current source 5 is a known type that outputs a current corresponding to field brightness and film sensitivity, for example. It consists of an optical amplifier. The charge level of the capacitor 31 is determined by the comparator C.
A reference voltage Vref3 is applied to the positive phase input of the comparator C3, and a reference voltage Vref3 is applied to the negative phase input of the comparator C3. The output of the comparator C3 is connected to the magnet 32 for closing and releasing the shutter blade, and the demagnetization of the magnet 32 releases the member for closing and releasing the shutter blade. Further, an inverter G is connected to the base of the switching transistor Tr12 for short-circuiting both ends of the capacitor 31.
The output of IO is applied to the inverter G10, and the Q output of the flip-flop FF3 described above is applied to the inverter G10. When the flip-flop FF3 is set, the inverter GI
The output of O becomes 1-level, cuts off the switching transistor TR2, and starts charging the capacitor 31. And when the output of 9 comparator C3 becomes H level,
Flip-flop FF6 through AND gate Gll
is set, and this pretend 1. The Q output of Pflosop FF6 is used for the initial reset node of the entire circuit. As described above, in the two embodiments, the AE delay time from when the trigger switch 24 breaks to when the exposure control circuit is activated is set by the current flowing from the constant current source 11 to the capacitor 11. Further, the FM delay time from when the trigger switch 24 breaks until it actually becomes a pinhole is set by the current flowing from the capacitor 11 to the constant current source I2 in addition to the AE delay time. In this case, the current value of the constant current source 1 corresponds to the mechanical delay time required for the charge level of the capacitor 11 to reach the reference level Vref2 of the comparator C2 from the ground level. The current value of the constant current source 2 is adjusted so that the charging level of the capacitor 11 changes from the reference level Vref2 of the comparator C2 to the reference level Vr of the comparator C1.
The time required to reach efl is adjusted so that it corresponds to the mechanical delay time during the closing operation of the shank blade. Next, the appropriate aperture when synchronizing the strobe is determined according to the film sensitivity and shooting distance, and when the strobe guide number is set to a constant value, the appropriate aperture is proportional to the shooting distance and inversely proportional to the square root of the film sensitivity. do. Therefore, the constant current sources 13 and I4 are adjusted so that their current values are inversely proportional to the photographing distance. Examples of constant current sources I3 and I4 are shown in FIGS. 3 and 4. First, FIG. 3 shows an example in which distance information is input from an autofocus mechanism. In fig. 13 is a distance measuring circuit for automatic claw cutting, and distance measuring circuit 1
3 generates a pulse corresponding to the shooting distance. The counter 14 is incremented by the pulse generated by the distance measuring circuit 13. 15 is a digital-to-analog converter that converts the output of the counter 14 into an analog current value; The output of each stage is output by adding/subtracting a correspondingly weighted current. Further, FIG. 4 shows an example in which distance information is input from the helicoid of the photographic lens. In Figure 4, transistor 1
6 and 17 each share a haze level, and transistor 1
6 has its base and collector short-circuited and acts as a diode. or. 18 is a potentiometer linked to the helicoid of the photographing lens. Therefore, the base level when current flows through the transistor 16, which acts as a diode, is determined according to the resistance value of the potentiometer 18. Since the transistor 17 shares the base with the transistor 16, the current flowing through the transistor 17 also depends on the resistance value of the potentiometer 18. It will be determined according to the resistance value of. Then, the current flowing through the transistor 17 is charged/discharged and supplied to the capacitor 11 as a current. Next, the operation of this embodiment will be explained with reference to the above matters and the time chart shown in FIG. First, the operation when no strobe is used will be explained. In the initial state, all flip-flops are initially reset, and current switch S1 to which the ζ output of flip-flop FF3 is applied is metering, but at this point, as a result of flip-flop FF2 being reset, the transistor Since TRI is conducting,
Both ends of capacitor 11 are short-circuited, and capacitor I
I is not charged. Now, 1. When the shutter button (not shown) is pressed. The release switch SS in Fig. 2 is metering, and at the same time the first
The blade opening/closing lever 4 shown in the figure is released. Therefore, the three-blade opening/closing lever 4 is rotated to the left by the biasing force of the spring 5, and in the course of the left rotation, the shutter blades 2 and 3 open the aperture 1e. In this way, in the process of the blade opening/closing lever 4 turning left, the trigger switch 24 breaks at timing T when the blade opening/closing lever 4 turns left by a predetermined amount before the aperture 1e reaches the pinball state. Then, due to the break of the trigger switch 24, the output of the AND gate G1 becomes H level, and the flip-flop FF2 is turned on. In this way, flip-flop FF2 is set,
When the ζ output becomes L level, the transistor TRI is cut off and the capacitor 11 can be charged. Now, since the flip-flop FF3 is in the current state, only the current switch S1 is metering by the ζ output of the flip-flop FF3, and when the transistor TRI is cut off, the capacitor 11 is connected to the constant current source 11.
The battery is charged by the current supplied from the battery through the current switch S1. Then, at timing T2 when the AE delay time has elapsed from the auto trigger timing T1, the charge level of the capacitor 11 is set to the reference level Vref2 of the comparator C2.
When the output of the comparator C2 reaches L level, this is inverted by the inverter 12 and inputs the flip-flop FFI. The Q output of flip-flop FFI is applied to AND gate G2 along with the Q output of flip-flop FF2, and since the output of flip-flop FF2 is already at H level, the timing when flip-flop FFI is sent is Then, the output of the AND gate G2 becomes H level and sets the free-seven block FF3. When flip-flop FF3 is set and its Q output becomes H level, inverter GI of exposure control circuit 3o
The output of O becomes L level, the transistor TR2 is cut off, and the exposure integration capacitor 31 is charged by the current flowing through the constant current source 5 in accordance with the field brightness, and its charge level rises. Then, the charge level of the capacitor 31 is determined by the comparator C.
When the reference level V ref3 of 3 is reached, the comparator C3
When the output reaches H level, the closing release magnet 32 is demagnetized, the blade opening/closing lever 4 shown in FIG. 1 rotates to the right, and the shutter blades II 2 and 3 close the aperture 1e. Also, at this time, as the output of the comparator C3 becomes H level, the output of the AND gate Gll also becomes the level ■(), and the flip-flop FF6 is set. The reset circuit operates and resets each part of the 5 circuits as appropriate.Next, we will explain the operation during photography using a strobe.In strobe photography, the operation after the shirt release until flip-flop FF3 is set is as follows. is the same as above. When flip-flop FF3 is set and its output goes to L level, current switch S1 breaks and current is no longer supplied to capacitor 11 from constant current source 1. The charging of the flip-flop FF3 is completed. Also, the Q output of the flip-flop FF3 is added to the ant game) G4 along with the G output of the flip-flop FF4, and since the flip-flop FF4 is recessed at this point, the flip-flop When FF3 is set, the output of Antoge-1-G4 becomes H level, causing current switch S2 to meter. Therefore, the charge accumulated in the capacitor 11 is the constant current source I
2, the charge level of the capacitor 11 decreases linearly. At a timing Ti when the FM delay time has elapsed from the auto trigger timing T1 (this timing T is the timing at which the aperture 1e becomes a pinhole), when the charge level of the capacitor 11 decreases to the reference level Vrefl of the comparator C1, the comparator C ] becomes H level and resets the flip-flop F F1. When the flip-flop FFI is reset in this way, its output is applied to the flip-flop FF4 via the antgame 1.G3,
Set 4. Now, when the flip-flop FF4 is turned on, the output of the AND gate G4 goes to the I level and breaks the current switch S2, so that the discharge of the capacitor 11 by the constant current source 2 is completed. On the other hand, at this point, the flip-flop FF5 is still in the reset state, so the flip-flop FF4 is sent to the Antogame 1-06.
The output becomes H level, and one of the inputs of Antogame 1, G7, and G8 becomes H level. At this moment, the flip-flop FFI has been reset, so the output of the Antogame G8 becomes H level, the current switch S3 is turned on, and the current flowing through the constant current source 3 causes the capacitor 11 to increase in inverse proportion to the shooting distance. The battery is charged by the current flowing through the constant current source (3). Then, when the capacitor 11 is charged to the reference level Vref2 and the flip-flop FFI is set,
The output of AND gate G7 becomes H level, the output of AND gate G8 becomes L level, current switch S3 breaks, and current switch S4 meters. Therefore, the charge accumulated in the capacitor 11 is discharged by the current flowing through the constant current source 4 in inverse proportion to the photographing distance. Then, the level of the capacitor 11 is the reference level Vref
When it drops to l, the flip-flop FFI is reset again. Thereafter, similarly, the capacitor 11 is repeatedly charged and discharged, and the flip-flop FFI is repeatedly set and reset. Therefore, after flip-flop FF4 is inputted, flip-flop F
A pulse synchronized with the Q output of the FI is output, and the ant game
1-G At the down edge of the output pulse of 9, the counter 22
is incremented. The counting output of the counter 22 is -fJJ, which is added to the detection circuit 21, and when the counting output of the counter 22 matches the film sensitivity information added from the film sensitivity input circuit 23, the -fJJ level is reached. Generates a match detection signal. Then, this minus number output signal is output from the AND gate G5.
is applied to flip-flop FF5 through
Using the Q output of No. 5 as a trigger, the strobe light emitting circuit 40 emits light. The exposure control circuit 30 is in operation even during this strobe photography, and after the strobe emits light in a two-pole manner, the output of the comparator C3 becomes the I level and the magnet 32 is demagnetized. At this point, the shutter blades 2 and 3 are closed and released. Furthermore, in the above example, the preset number of the counter 22 corresponds to the film sensitivity, and the current values of the constant current sources I3 and I4 are made inversely proportional to the photographing distance.
The current values of the constant current sources I3 and I4 may be made inversely proportional to the square root of the film sensitivity, and the preset number of the counter 22 may be made proportional to the photographing distance. Furthermore, in the above example, the oscillation period was adjusted according to the shooting distance by adjusting the current values of the constant current sources I3 and I4, but in order to adjust the oscillation period according to the shooting distance, The reference level V ref corresponds to 5 shooting distances.
3 and Vref4 may be adjusted. Furthermore, in the above example, the progress of the photographing sequence is sequentially stored using the flip-flop circuits from flip-flop FF2 to flip-flop FFS and the AND gate, but the progress of the photographing sequence can be stored using shift registers and counter circuits. may be stored, and the various operation sequences may be switched by the output of each stage of the shift register, or the operation sequence may be switched by decoding the count value of a counter. Furthermore, in the above, the capacitor 11 is used as a time constant circuit for measuring the fil A E delay time, (21) a time constant circuit for measuring the FM delay time, and (3) a time constant circuit for measuring the strobe tuning time. Although an example has been shown in which the time constant circuit 1 is used sequentially, the time constant circuit 1 can also be used as a time constant circuit for setting the forced closing timing of the shutter blade in photography using a strobe, for example. In that case, the shutter blade may be forcibly closed by a carryover signal from the counter 22, for example.

【effect】

As explained above, in the present invention, the capacitor 11
is charged and discharged between the level upper limit value and the level lower limit value, and the switching timing of charging and discharging the capacitor 11 is made to correspond to the progress of the shooting sequence. Therefore, - capacitor time constant circuits can be used as multiple timer circuits. Can be used for both purposes. Therefore, according to the present invention, external attachment to IC circuit components can reduce the number of components, and soldering reduces the number of parts, reduces manufacturing costs, reduces circuit mounting space in the camera, and causes failures. Reducing the number of parts will bring you many benefits.

[Brief explanation of drawings]

FIG. 1 is a mechanical diagram showing an example of a program shutter to which the present invention is applied, and FIG. 2 is a circuit diagram showing an embodiment of the present invention.
Figures 3 and 4 are circuit diagrams each showing an example of a constant current source circuit that outputs a current in inverse proportion to the shooting distance, Figure 5 is a time chart showing the operation timing of the circuit shown in Figure 2, and Figure 6 1 is a characteristic diagram showing general aperture characteristics of a program shutter as shown in FIG. 1... Shutter base plate 2. 3... Shutter blade 4... Blade opening/closing lever 10... Oscillation circuit 11.
...Capacitor 12...Inverter 20...
Sequence control circuit 21... - Number output circuit 22... Counter 23.
... Film sensitivity input circuit 24 ... Trigger switch 30 ... Exposure control circuit 3
1... Capacitor 32... McNet 40.
・・Strobe light emitting circuit 11・I2・I3・I4・I5・・Constant current source FFI・
FF2, FF3, FF4, FF5, FF6...Flip-flop C1, C2, C3...Comparator patent applicant Konomaru Co., Ltd. Patent attorney Koji Murakami Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A shutter blade that also serves as an aperture blade is opened to obtain a predetermined aperture characteristic, and a capacitor is provided with a starting point when the shutter blade operates to a predetermined position before becoming a pinhole. In a program shutter timing control device that operates a time constant circuit to control the timing of automatic exposure photography and the timing of photography using a strobe, a constant current source for charging and a constant current source for discharging the capacitor constituting the time constant circuit. A constant current source for use is connected through a current switch, and the switching operation of the current switch charges and discharges the capacitor between the upper level limit value and the lower level limit value, and the switching operation of the current switch 1. A timing control device for a program shutter, characterized in that a storage means for storing time sequential information is provided, and the timing of automatic exposure photography and the timing of photography using a strobe are controlled at the switching timing of the output of the storage means. (2) In the program timing control device according to claim 1, the end timing of the first half cycle of the charging/discharging cycle of the capacitor is made to correspond to the activation timing of the automatic exposure control circuit, and The end timing of the next half cycle of the charging/discharging cycle is made to correspond to the pinhole timing of the shutter blade, and the subsequent charging/discharging operations of the capacitor are counted to control the strobe synchronization timing. Features a programmable shutter timing control device.