JP2525347B2 - camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly to a camera in which a cutoff time for forcibly closing a shutter is set.

Conventionally, the following two methods have been adopted as a shutter method of a camera having diaphragm blades and shutter blades for interlocking to a certain field brightness.

One is a method in which exposure control is performed in a half-open region of the shutter opening when the field is high in brightness, and exposure control is performed in a fully open region of the shutter opening when the field is low in brightness. This method uses a light-receiving element (CdS, etc.) for external photometry.
Alternatively, since the gamma characteristic of the exposure time has to be changed between the half open region and the full open region, there are problems that adjustment becomes difficult and the cost increases.

On the other hand, the other one is a method in which the shutter opening speed is slowed down and exposure control is performed in a half-open region at high brightness and low brightness, but this may be the case where the light receiving element has a constant gama characteristic. That is, in this method, the range of the interlocked field brightness is the case where the shutter opening is a half open region. Therefore, the problem with this method is how to extend the interlocked field brightness range and how to shorten the effective exposure time and prevent camera shake.To that end, the shutter opening should be fully opened. Exposure control should be performed until the state is reached, and the fully open region thereafter should be minimized.

Further, in general, when the field brightness is low, the shutter opening time becomes long, and camera shake easily occurs. In order to solve this, it has been proposed that the cutoff time is set, but if the cutoff time is too short, there is a problem that the interlocked field brightness range becomes narrow. Conventionally, the setting of the cutoff time is performed by adjustment, but there is a problem that the cost is increased by the adjustment.

Further, various methods have been proposed in order to solve the above-mentioned problems, one of which is a certain second after a switch for counting the exposure time (hereinafter, referred to as a count switch) is turned on. This is a method of setting so that the time is cut off after a second. However, this method has the following drawbacks due to individual differences in the opening speed of the shutter, errors in the electronically set time until the time is reached after the count switch is turned off, and variations.

It is necessary to open the shutter to the maximum aperture in order to extend the interlocked field brightness to low brightness, but in that case, the shortest cutoff time in consideration of error, variation, etc. is better than the slowest opening speed of the shutter. Must be set to be long. However, in this case, in the case of a combination of the fastest opening speed of the shutter and the longest cutoff time in consideration of errors, variations, etc., especially when the field brightness is low, the effective exposure time becomes long and camera shake occurs. There is a risk of getting tired.

On the other hand, as another method, there is a method in which, after the shutter is fully opened, the cutoff switch is actuated by traveling of the control member to immediately set the cutoff time. This eliminates the drawbacks described above, but has the following drawbacks.

In the case of a method in which the control member abuts or engages with another member to turn on the cutoff switch after the shutter is fully opened, the number of parts (abutting member, switch, etc.) increases and the cost increases. Also, since the cutoff switch must be operated between the time the shutter is fully opened and the time when the control member reaches the final position, either the timing at which the cutoff switch is operated must be adjusted, or the shutter is fully opened. There is a drawback in that the stroke of the control member must be lengthened from the start of the control member until it reaches the final position.

The present invention has been made in view of the above problems and drawbacks, and an object of the present invention is to provide a camera that extends the low brightness side of the interlocked field brightness and further shortens the cutoff time.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural diagram of an embodiment of the present invention. In FIG. 1, reference numeral 1 is a release lever, which is fitted in the grooves 1a and 1b so as to be vertically slidable with the projections 21a and 21b of the main body (not shown). 21a,
21b is regulated by contacting the grooves 1a, 1b. Reference numeral 22 is a spring that biases the release lever 1 in the b direction. Reference numeral 2 is a switch that is closed to start energization of a shutter control circuit (not shown). Reference numeral 4 is a set plate, which is a protrusion 2 of the main body (not shown) in each of the grooves 4a and 4b.
It is fitted to 1c and 21d so that it can slide in the left-right direction. A set plate spring 5 urges the set plate 4 in the c direction. A leaf spring 3 has a portion 3a and a portion 3b, and an end surface 4c of the set plate 4 is locked at the portion 3b. A gear 6 is rotatably attached to the main body and meshes with the rack portion 4e of the set plate 4. Reference numeral 7 denotes a gear that is rotatably attached to the main body and meshes with the gear 6 in the small gear portion 7a. 8 is rotatably attached to the main body, and a gear 7 is provided in the small gear portion 8b.
This is a member that meshes with the large gear portion 7b. Reference numeral 9 denotes an ankle that is rotatably attached to the main body, and an escape wheel 8a of the member 8
To control the speed of movement of the set plate 4 in the c direction. Further, 10 is a contact piece and 11 is a printed circuit board, which together with the contact piece 10 constitute a switch 102. 12 is a rotor, on the surface of which a coil is formed by a conductive wire 16, and the rotor 12
Is rotatably attached to a main body (not shown). 14,1
5 is a magnetic field that acts in a direction perpendicular to the paper surface by a magnet (not shown),
The directions of the magnetic fields are opposite to each other. Reference numeral 13 is a spring that biases the rotor 12 in the direction opposite to the a direction.
Reference numeral 17 is a stopper for restricting the rotation amount of the rotor 12 in the direction opposite to the rotation direction (direction a), 18 is a blade driving pin fixed on the rotor 12, and 19 and 20 are blade driving pins 18. This is a driven shutter blade that also serves as a diaphragm blade.

Next, the operation of the shutter configured as shown in FIG. 1 will be described.

When the release lever 1 is pushed down from the state shown in FIG. 1, the projection 2c of the release lever 1 closes the switch 2, and the shutter control circuit is energized. When the release lever 1 is further pushed down, the leaf spring 3 bends, and the engagement state between the end surface 4c of the set plate 4 and the 3b portion of the plate spring 3 is released, and the set plate 4 is moved to the right by the urging force of the spring 5. However, at that time, the rack portion 4e and the gear 6, the small gear portion 7a of the gear 6 and the gear 7, the large gear portion 7b of the gear 7, the small gear portion 8b of the member 8, and the escape wheel portion 8a of the member 8 and the pallet fork. The moving speed of the set plate 4 is appropriately controlled by the meshing of 9 with each other. When the set plate 4 runs, the contact piece 10 and the substrate 11
The switch 102 composed of is first in the OFF state (first state).
To the ON state (second state), and at the same time, the conductor 16 is energized by the shutter control circuit. When the conductor 16 is energized, the rotor 12 rotates in the direction a against the biasing force of the spring 13 due to the electromagnetic driving force, and the cam surface 12a abuts against the standing bent portion 4d of the set plate 4. In this state, the shutter is not open yet.

Further, the rotor 12 rotates following the set plate 4, and when the rotor 12 rotates by a predetermined angle, the shutter opening finally becomes a pinhole. At that time, the switch 102 composed of the contact piece 10 and the substrate 11 changes from the ON state (second state) to the OFF state (third state), and at the same time, the shutter control circuit starts counting the exposure time.

Further, as the set plate 4 moves, the shutter blades open and open gradually, but when the set plate 4 reaches a predetermined position, a switch composed of the contact piece 10 and the substrate 11 is formed.
102 is from the OFF state (third state) to the ON state (fourth state)
Change to The shutter control circuit cuts off the power supply to the conductor 16 after a predetermined time from this point. This is the cutoff time. When the automatic exposure (AE) time is earlier than the cutoff time, the shutter control circuit cuts off the power supply to the conductor 16 at the time of AE time. When power to the conductor 16 is cut off, the rotor
The spring 12 is rotated in the direction opposite to the direction a by the biasing force of the spring 13 to close the shutter blade, and abuts the stopper 17 to stop. This completes the exposure operation.

Next, the set plate 4 is stored in the left direction against the urging force of the spring 5 by a known means, and the end face 4c pushes the inclined surface 3a of the plate spring 3 to bend the plate spring 3. When the accumulating force is released when riding over the portion 3a, the end surface 4c of the set plate 4 and the portion 3b of the leaf spring 3 are engaged, and the shutter as shown in FIG. 1 returns to the set state. .

 Next, the abort time will be described in detail.

As a condition, as described above, it is necessary to make the fully opened state of the shutter as short as possible and be sure to fully open it.

FIG. 2 is a graph of opening characteristics, where the vertical axis s is the opening area and the horizontal axis x is the stroke of the set plate. In FIG.
Set the stroke of the set plate at which the shutter is fully opened to x ₁ . If the variation of the stroke due to the variation of the parts of the set plate 4 is A, the center value of the engagement or contact position of the set plate after the shutter is fully opened is And must be. Further, if the variation in the stroke of the set plate when the switch 102 constituted by the contact piece 10 and the substrate 11 is in the above-mentioned fourth state is B, the stroke of the set plate when in the fourth state Is Must be set to.

Now, assuming that the traveling speed of the set plate is C% varied in the direction in which it increases and in the direction in which it slows due to individual differences, and if it takes D seconds with a stroke of x ₁ , the switch 102 is the fourth. After reaching the state, If it is cut off later, the shutter will be fully opened. At this time, the time when the switch 102 is in the fully open state is the longest when the stroke of the set plate when the switch 102 is in the fourth state is x _1, and the time when the switch 102 is in the fully open state is Is. By the way, if the cutoff time is after a certain time from the above-mentioned third state, by applying the above example, from the time when the count switch is ON It must be cut off later, and the one that is in the fully open state for the longest time is the fastest one due to variations in the traveling of the set board. Becomes In the case of this embodiment, When compared with C, C may usually be 20 to 30% or more, but the variation B in the formula is naturally a small value for the stroke X ₁ , so this embodiment is more advantageous. It will be obvious.

As described above, the timing at which the count switch operates is almost the same as the timing at which the shutter becomes a pinhole, and the set plate when the switch 102 constituted by the contact piece 10 and the substrate 11 is in the fourth state. Since the variation in the stroke of 4 may be relatively large, the count switch and the switch for the cutoff time can be configured by the same substrate and the contact piece as in the present embodiment.

Next, the electrical operation will be described with reference to the control circuit shown in FIG.

In FIG. 3, 2 is the above-mentioned switch for supplying the power supply 101 to this control circuit, 16 is a conducting wire installed on the surface of the rotor 12, 102 is a switch composed of the substrate 11 and the contact piece 10, 101 is a power source, 103 to 109 are resistors, 110 and 111 are capacitors, 112 is a photoconductive element such as CdS, and 113 and 114 are
NPN type transistor, 115 is a comparator, and the comparator 115 includes resistors 105 to 107, a photoconductive element 112, and a capacitor.
An exposure control circuit 131 is configured with 111 and the transistor 113. The exposure is started by changing the level of the signal c on the input side of the resistor 105 from “H” to “L”, and from the “H” level to “L” depending on the intensity of light incident on the photoconductive element 112.
The signal d from the comparator 115, which changes to the level, is output after a predetermined time. Further, 116 to 130 are logic circuits, 116 to 119 are inverters, 120 is a NAND gate, 121 to 121.
Reference numeral 123 is an AND gate, and 124 to 127 output "H" level to the Q output and "L" level to the latch output when the "L" level signal is input to the R input and the "H" level signal is input to the S input. RS flip-flops, 128 and 129 output "L" level to Q output according to CL input "H" level, count predetermined pulse input at CL input "L" level and output "H" level to Q output The ripple counter 130 is an oscillator that outputs a clock pulse to the clock inputs of the ripple counters 128 and 129.

Next, the operation of the shutter control circuit configured as shown in FIG. 3 will be described with reference to the timing chart shown in FIG.

First, when the release lever 1 is pushed down, the switch 2 energizes the control circuit from the power supply 101, and the resistance 1
Via 03, the capacitors 110 are charged and the voltage at their connection points rises. That is, it acts as an integrating circuit. The inverter 116 is "H" until the input reaches the specified potential.
Outputs a level, and when it reaches a predetermined potential, the output switches from "H" level to "L" level. Therefore, the output signal a of the inverter 116 becomes "H" level for a predetermined time after the power supply to the control circuit is turned on. During this period, the four RS flip flops 124 to 127 have their R inputs at the "H" level,
Each Q output is set to "L" level and the output is set to "H" level. Therefore, the output of RS flip-flop 126,
That is, since the signal g is at "H" level, the counter 129
CL input becomes "H" level, and its output Q remains "L" level. Further, since one input of the NAND gate 120 is at "L" level, its output is at "H" level, and accordingly, the output Q of the counter 128 remains at "L" level. Further, since the Q output of the RS flip-flop 125, that is, the signal f is at "L" level, the output of the inverter 119 is at "H" level, and the two inputs of the AND gate 122 are both at "H" level. Output signal c is "H"
It becomes the level, and the NPN transistor 113 is passed through the resistor 105.
Is turned on, the connection point between the capacitor 11 and the photoconductive element 112 drops to zero potential near the ground, and the potential is lower than the connection point of the resistors 106 and 107, so the signal d output from the comparator 115 is "H". It becomes a level. Further, since the Q output of the RS flip-flop 124, that is, the signal e is at the "L" level, the output of the AND gate 123, that is, the signal i remains at the "L" level, and the NPN transistor 114 maintains the OFF state. , The conductor 16 of the rotor is not energized. What is being done at this point is the energization of the control circuit and the resetting of each circuit.

Next, the release lever 1 is further pushed down to set the plate 4
When is running, switch 102 turns from OFF to ON. The input of the inverter 117 changes from "H" level to "L" level,
The output signal b goes from "L" level to "H" level. Therefore, the R input of RS flip-flop 124 becomes "L" level, the S input becomes "H" level, and the Q output becomes "H" level.
The level signal is latched, and the signal e maintains the "H" level. At this time, since the signals d, h, and e are all at the “H” level, the output of the AND gate 123, that is, the signal i
Goes from the "L" level to the H level, the NPN transistor 114 is turned on through the resistor 108, and the conductor 16 of the rotor is energized.

Furthermore, the set board 4 runs and the switch 102 turns from ON to OFF.
Then, the input of the inverter 117 shifts from the "L" level to the "H" level through the resistor 104, and the output thereof, that is, the signal b shifts from the "H" level to the "L" level. Then
The output of the inverter 118 changes from "L" level to "H" level, both inputs of the NAND gate 120 become "H" level, and its output becomes "L" level. Therefore, since the CL input of the counter 128 is at "L" level, the counting operation of the input clock pulse is started. On the other hand, AND gate 1
Since the output of 22, that is, the signal c shifts from the “H” level to the “L” level, the NPN transistor 113 switches from ON to OFF, the capacitor 111 is charged through the photoconductive element 112, and the connection point between them. That is, the potential of the inverting input terminal of the comparator 115 rises according to the resistance value of the photoconductive element 112 corresponding to the illuminance. Further, when a "H" level is output to the Q output of the counter 128 after a lapse of a predetermined time, the R input of the RS flip-flop 125 becomes the "L" level and the S input becomes the "H" level. "Latches the level, that is, the signal f becomes the" H "level. In addition, the inverter 11
Since the input of 9 is at "H" level, the output becomes "L" level, and the output of the AND gate 122 having it as one input is at "L" level, that is, the signal c remains at "L" level.

After a while, the illuminance on the photoconductive element 112 is relatively high, and the potential of the inverting input terminal of the comparator 115 changes to the resistor 106.
When the potential obtained by dividing the power supply voltage by 107 and 107, that is, the potential of the non-inverting input terminal of the comparator 115 is exceeded, the output of the comparator 115, that is, the signal d changes from the “H” level to the “L” level, and the AND gate 123 The output of turns from "H" level to "L" level. Therefore, the NPN transistor 114 loses its input (base) current and turns from ON to OFF.
The conductor 16 of the rotor is turned on and off. The timing chart in this case is the signals d and i in FIG.
At each time point, and at the time of
This is the case when turning to a level. At this time, the conductor wire 16 of the rotor is de-energized, so that the rotor loses the electromagnetic force, and the shutter blades perform the closing operation as described above to complete the exposure operation to the film. In this case, the film exposure satisfies the preset proper exposure amount.

However, if the illuminance on the photoconductive element 112 is low and the film exposure cannot be completed within a predetermined time, leaving the shutter blade open unnecessarily causes camera shake due to long-time exposure, and the photographer It is not uncommon for photos to be very unsatisfactory. Therefore, in such a case, it is desirable to finish the exposure within a time that does not cause camera shake, and to finish the exposure within a predetermined time even if the film exposure amount is slightly insufficient. This is the above-mentioned so-called abort time. The operation of the control circuit in that case will be described below.

Originally, the output of the comparator 115, that is, the signal d
At the time shown in FIG. 4, if the "H" level shifts to the "L" level, the switch is moved by the traveling of the set plate 4.
102 turns from OFF to ON again. Then, the inverter 11
Since the input of 7 becomes "L" level, its output becomes "H" level, and the Q output of the RS flip-flop 125, that is, the signal f is also maintained at "H" level.
The output of the gate 121 is at "H" level, the R input of the flip-flop 126 is at "L" level, and the S input is at "H" level, so that the output is latched at "L" level, and accordingly the signal g
Changes from "H" level to "L" level. Therefore,
Since the CL input of the counter 129 is also changed from the “H” level to the “L” level, the reset state is released and the counting operation of the clock pulse of the clock input is started.

When the "H" level is output to the Q output of the counter 129 after a predetermined time has elapsed, the R input of the RS flip-flop 127 becomes the "L" level and the S input becomes the "H" level. The signal level is changed to the L "level, the" L "level is latched, and accordingly, the signal h is maintained at the" L "level (time point in FIG. 4). Therefore, the output of the AND gate 123 changes from “H” level to “L” level, and the NPN transistor 114 cuts off its input (base) current and changes from ON to OFF.
The conductor wire 16 of the rotor is turned on and off, and the shutter blades are closed as described above to complete the exposure operation.

In the case of this control circuit, due to the chattering when the switch 102 turns from ON to OFF, the switch 102 turns from OFF to the second time.
In order to prevent erroneous detection of the ON signal, that is, after the counter 128 is reset, that is, the switch 102
After the switch turns from ON to OFF, the switch 102 turns ON again after the clock pulse has been counted by the counter 128 for a predetermined time.
Detect the signal that turns on from FF. The time set by the counter 129 and the RS flip-flop 127 can be set arbitrarily.

As described above, the present invention has the following effects.

(1) Since the shutter always opens up to the maximum aperture when the object scene is cut off at a low brightness and the time is cut off, it can be linked up to a long distance during flash photography.

(2) Since the cutoff switch can be shared with the board of the count switch, the number of parts is small, and it is not necessary to adjust the timing of the cutoff switch, so that the cost can be reduced.

(3) It is not necessary to mechanically strictly control the operation timing of the cutoff switch, and camera shake can be minimized without limiting the variation in individual shutter opening speed.

[Brief description of drawings]

FIG. 1 is a structural diagram of an embodiment of the present invention, FIG. 2 is a graph of aperture characteristics, FIG. 3 is a control circuit diagram of a shutter, and FIG. 4 is a timing chart of the control circuit of FIG. 1 …… Release lever, 4 …… Set plate, 10 …… Contact piece, 11 …… (Print) board, 12 …… Rotor, 19,20 …… Shutter blade also used as diaphragm blade, 102 …… Switch.

Claims (2)

(57) [Claims] 1. A shutter, a first switch for starting measurement of the closing timing of the shutter according to the brightness of the subject, and the shutter is forcibly closed at a predetermined time when the subject has low brightness. In a camera having a second switch for starting timing of a cutoff time to be started, the operation timing of the second switch for starting timing of the cutoff time is started. After the operation timing of the first switch for, and after the exposure start of the shutter,
The camera is characterized by being set before the fully open state. 2. The camera according to claim 1, wherein the first switch and the second switch are formed on the same substrate.