JPS6057327A - Program shutter - Google Patents

Abstract

PURPOSE:To make a shutter charge mechanism unnecessary and make the release operation soft by step-driving a motor in the normal direction with the number of steps corresponding to an exposure quantity and step-driving it in the reverse direction when a correction time is elapsed from the last step-driving. CONSTITUTION:When the number of interpolating clocks CK3 coincides with a preset value of a counter 43, a normal/reverse switching circuit 44 is operated to output an inverting signal. Simultaneously, the pulse movement direction of a pulse motor driving circuit 46 is switched, and a step motor 11 is reversed forcibly. A sector starts closing gradually by this reverse of the pulse motor, and the motor is step-driven each time when a driving pulse is inputted; and when the first counter 42 is reduced to zero, a gate G1 is closed to stop the step driving pulse. Simultaneously, the sector is returned to the original position to close the optical path. Thus, the exposure is controlled finely independently of the inter-step moving speed of the motor, and especially, the exposure precision for short seconds is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a program shutter, and more specifically, to a program shutter in which both the opening and closing strokes of the blades are controlled by a step motor to obtain an appropriate amount of exposure. be. Conventionally, such a device has a pulse train for driving a step motor, and when the camera is released, a pulse (hereinafter referred to as "positive pulse") for rotating the motor in the full positive direction is applied to the blade. The aperture diameter gradually increases, and when the number of pulses corresponding to the subject brightness is applied, the motor is switched to a pulse in the reverse direction (hereinafter referred to as a reverse pulse), which is the same as the positive pulse described above. It is thought that by applying several reverse pulses to the motor, the opening of the blade is gradually made smaller and finally closed, returning to the initial state and completing the entire exposure operation. However, with this method, it does not pose much of a problem when the brightness of the subject is darker than a certain level, but when the brightness is bright, the exposure accuracy deteriorates. There is.

In other words, the rotational speed of the rotor varies depending on the design of the motor, but it is approximately 300 to 1ooopps (Pu1se
A speed on the order of 5 seconds per 5 seconds is generally the maximum speed that can be obtained. Therefore, the exposure time for the highest brightness is naturally determined by the rotational speed of the rotor, and for the second brightness after the highest brightness, the rotor will rotate one step angle more. .

As a result, for example, even if the proper exposure amount at the first step of the rotor is LV17 (exposure time - clove o o be o) and the error is zero, the time required for one step of the rotor will be different from the above speed. Then 1~s m se
c. Figure 4 shows a schematic exposure diagram at this time, but if the time required for one step of the motor is 2.
! Even as m5ec, the exposure amount for the second brightness (Q2) is the exposure amount for the second brightness (Qt) for the first brightness above.
) is approximately 9 times larger. In other words, the second brightness is LV1
4, and there will be a considerable exposure error for brightness between that range. This can further improve the motor speed, the speed at which the blades open,
This can be improved by making the slope of the open line in Figure 4 gentler, but increasing the motor speed requires increasing the applied current or improving the rotor's magnet material, which naturally limits the speed. It is necessary. Also, if you look at the current trends in photosensitive materials,
A: High sensitivities such as 400, 800, and 10DO are becoming available. Under such circumstances, the shutter is required to control exposure at relatively short seconds. Therefore, the present invention aims to propose a method that can minimize the inherent error on the high brightness side as described above, and furthermore, can achieve shorter time control than ever before.

According to the present invention, the above objects include a reference oscillator, a divider connected to the oscillator, a pulse signal generator connected to the frequency divider and determining the total rotational speed of the motor, a stepping motor,
A pulse direction converter for changing the driving direction of the stepping motor, and a brightness detection circuit for detecting the entire subject brightness are provided, and the stepping motor and the sector are connected directly or indirectly, so that the stepping motor changes the sector opening and the brightness detection circuit. In order to control the closing stroke, the pulse direction converter t can also be used as information for the brightness detection circuit for the pulse train emitted by the pulse signal generator, and the width of the motor drive pulse at the time of direction change is completely arbitrary. This is achieved by changing to .

The present invention will be described below according to embodiments shown in the drawings.

First, to explain the structure of the shutter shown in Figures 1(A) and 1(B), (1) has one shutter plate and the corresponding plate (1)
A front plate (2) for holding the lens is attached with screws. An opening (0) for a lens is formed in the center of the plywood (1) and the front plate (2). At the same time, between the two, there is formed a sector chamber (3), which will be described later, in which all sectors are housed. (4) is a sector ring, which is supported rotatably around the optical axis by the front plate (2). The sector ring (4) is biased clockwise by a spring (7) and supported so as not to be pulled out according to the theory (5).The sector ring (4) is connected to a bin (6) fixed to the plywood (1) The sector pin (4C) has a rotation part (4a) that regulates the rotation range, a sector pin (4C), and a tooth part (4d)' (to be described later). , is secured to the sector (, 3) of the sector chamber in the relationship between the axis and the groove.

The sector (3) is rotatably supported by a sector pin (3) fixed to the front plate (2).

In the figure, the opening is determined by two sectors (3) and (3b). <v>+ (it>
are the first gear and the second gear, which are respectively driven by rotating shafts (11, 12) fixed to the front plate (2)! The pinion (9a) of the first gear meshes with the teeth (4d) of the sector ring described above, and the first gear (9)
meshes with the pinion (10a) of the second gear. (
16) is a pinion attached to the rotor (22) of the motor (M) described later, and the above ij 2 gear (10)
It meshes with the. 1, (15) is a pillar fixed to the front plate (2) and has a female thread for attaching the motor. .

Next, the motor (M) shown in Figure 2 (A) (,B)
To explain the structure, (16) is the motor base plate, which has a mounting hole (16a) that engages with the pillar (15) mentioned above, and also has a pillar to which the two stators (1418) and the motor top plate (19) k, which will be described later, are attached. (20) and a guide pin (21) for guiding the positions of both the stators (17, , 1B). (22) is a magnetic rotor, with two poles of N fist 8 magnetized on the outer periphery.
It is fixed to the rotor shaft (23). The rotor shaft has a guide formed on the motor upper plate (19) at its upper end.

It is rotatably supported by the hole, and at its lower end is rotatably supported by the motor base plate (16).
16) f penetrates, and the aforementioned pinion (13) is attached to its tip.
) is fixed. Both stators (17, 18)
) are arranged at regular intervals from each other, and each leg (17a, 18a) has a first and M2 coil (Ll,
L2) Force; inserted. Magnetic poles for driving the upper rotor (22) are formed in the centers of both stators, and the details thereof will be explained below. To explain the shape of the first stator (17) placed at the top, a hole (17b) is formed in the center with a gap of one foot from the outer periphery of the rotor (22). The outer contour of the center is located near the 01 axis, which is tilted at approximately 45 degrees with respect to the reference axis (X, Y).
c@) 75' is formed, &-J, thick part (17dl,
17d is formed. This is VC, first stator (
17), the thick part (17dl, 17)
d2) can be made as a magnetic pole. The second SFO-1 (18) placed below the axis fC1 has a thick part (18 dl) near the 01 axis.

18+1. ) is formed, and a narrow part (18
cl, 18c2) is formed, so the magnetic pole of the first stator (18d1118d2) is arranged perpendicular to the magnetic pole of the first stator (17(1,, 'l'7d, ). That is, The pole of the rotor (22) is the coil (L1+Lx) vct flow is the flow J'
If not, the magnetic poles of both stators (17 (II
, 17 d, 2 degrees or 18 d, , 18 d2) and can be stopped at 90 degrees. Also, the magnetic pole parts (17d, 171) of both stakes (17°18) are
2. The above-mentioned foot parts (17a, 18a) extend from the "or 18d4, 18a2) part, and the iron core (24
) is short-circuited and a magnetic circuit is formed. At first, these members are attached to the coil (L) on the motor base plate (16).
1) Place the inserted second stake (18) while positioning it with all the guide pins (21), then place the first stator (17)? 11- Place in the same way, and then add an iron core (
24) Place the rotor (22) on top of it in the center
Then, place the motor upper plate (19) on it and attach it with screws (25), thereby constructing the motor as one block. Motorf formed in this way.

As mentioned above, the pinion (1 lock) is attached to the tip of the rotor shaft.
3) After Q is fixed, it is attached to the pillar (15) on the base plate (1) with screws to form a shutter mechanism.

Next, the circuit diagram shown in FIG. 6 will be explained.

(101) is an oscillation circuit such as a crystal resonator, (IO
2) is a brightness detection circuit that has a light receiving element such as a CDE and converts the brightness of the subject into the number of pulses, (103) (104)
is the reset/curse generation circuit, and (103) is the switch 8WI is 01! 'F7JJ) et al ON vc na ivy,
(104))! When the input signal (power level: vGs level (hereinafter referred to as "L") or vDDV level (hereinafter referred to as °H) changes by K, each output generates a short pulse, and the specified circuit is activated. (106) The counter counts the total number of pulses output from the 111 (102). (107) is an arithmetic circuit that calculates the number of pulses counted by the counter (106) and the switch. f
This is for calculating information such as film sensitivity encoded in ff' (1013) to obtain an exposure value.

(109) is ROM, (110) and (111) are counters, (112) is pulse signal generation circuit, (113) &1
A frequency dividing circuit, (114) a ring counter whose shift 1/direction can be changed, (115) to (118) jj%-ter driver, (M) &; I, a stepping motor.

Below, to explain the entire operation, the power switch (not shown) is 0I.
After JI, when the switch 8w1 is turned on by pressing down the camera's release button in the first step, a pulse is output from the reset pulse generation circuit (105) and the counter (106) is reset. This reset pulse is also input to the brightness detection circuit (102), and the post-reset brightness detection circuit (102) starts operating. The brightness detection circuit (1'02) inputs the clock signal from the frequency dividing circuit (15) to the counter 6 only during a time period in which the subject brightness is fully logarithmically compressed using, for example, a CDS and a diode. That is, the number of pulses input to the counter (1m6) is set to double when the brightness reaches V2, and triple when the brightness reaches 1/IK, and performs AD conversion. The number of pulses thus counted by the counter (106) is then input to the arithmetic circuit (107).

The arithmetic circuit (7) is used to convert the film sensitivity, which is input as a code through the switch (1, 08), into a numerical value and perform apex calculation.

In addition, 'r, 'Ef! Since this is based on a program shutter in which the exit blades and the diaphragm blades are used as both, the aperture calculation is not performed in the apex calculation. Arithmetic circuit (
The value calculated in step 107) is used as an address for accessing all the data written in the ROM (109). The ROM (109) stores exposure data for obtaining the necessary exposure amount determined by the brightness of the subject and the film sensitivity. The reason why ROM was used here is that the sector gradually opens over time, and the case where the aperture value is non-linear with respect to time is taken into consideration. Exposure data fJ, stepping motor CM) The total number of steps in the forward direction (the shutter blade opening direction is called the closing direction, and the closing direction is called the reverse direction). A set of time data indicating the time for forward rotation of the amount is stored in the ROM (109) in the counters (110) and (111), respectively.
) forwarded.

The above operations are sequentially and continuously performed after the switch SW1 goes to zero, and the data necessary for exposure is obtained.

Next, the exposure operation will be explained. When the release button is pressed down further, the switch l'1W2dJON is activated. This signal is connected through the reset terminal V of the pulse signal generation circuit (112) and the OR gate (129) y, and when the switch 8W2 is turned on, the pulse signal generation circuit (
112) Hari Nanatsutowo was lifted.

Counting of the signals from the frequency dividing circuit (115) is started.

The function of the pulse signal generation circuit (112) is composed of a counter, and is a trap that generates pulses with a -leg period.
The cycle created here is the cycle of one step of the stepping motor. For example, if you want to rotate a stepping motor at 3me per step, set the period of the output signal of the pulse signal generation circuit (112) to 5me, and set it to 2.5m.
If you want to rotate by s, use a signal with a period of 2.51nB?
It may be output from the pulse signal generation circuit (112). The output of the pulse signal generation circuit (112) is
10) and the ring counter (114)
A motor driver (115
) to (118) are connected, and the coil of a stepping motor (M) is connected to these drivers as shown in the figure.

The contents of this ring counter are all Q at the beginning, 1 = Q
2="H", Q3=Q4="L", and by shifting one pit to the right or left in response to all inputs, the stepping motor (M) rotates forward or backward. The number of steps written in the counter (110) by which the motor should rotate in the positive direction is calculated by the counter (1j
According to the output of 2), the paddy grain is reduced by 4, and at the same time, the stepping motor (M) rotates in the positive direction by 1 step each time the pulse signal generation circuit (112) is subtracted by 1. That is, in FIG. 2, the above output is the first coil (Ll)+
I input the 2nd coil (L2), but the 1st coil (L2)
Since the phase of L5) is input so as to be different from the phase of the second coil (Ll), the rotor (14) starts rotating fully clockwise, and this movement is caused by the rotation of the binion (13) and Tsuru2 The gear (10), the first gear (9) are fully valved, and the sector ring (
4) Then sector (3, 3b) r:r begins to open. Callan p-(+10) is -1thl: When the number 7c is subtracted sequentially and the content becomes 0, the OR gate (120
) becomes “L”. This “L” signal is
How many months of the frequency divider circuit (16) that is input to the gate (22) and input here I' passes through the A N D gate (122) and the contents of the counter (11, -1)? Subtract sequentially. When the content of the counter (Ml) becomes 0, the output of the OR gate (123) becomes "L", and this signal is the OR gate connected to the output of the OE game (120) which is L''VC. (124) also becomes Ln. Due to this signal, the output of the forward/reverse control circuit (125) changes from L'' to "H".

(The state of this output does not change until the power is turned off once). The output V of this forward/reverse control circuit (125),
Arithmetic circuit (107), ring counter (114'),
Reset pulse generation circuit (104).

NAND gate (126) is connected to V. When this signal changes to "H", the ring counter (114)
If the data shift direction of the ring counter (114) is changed, for example, when the data is "L", the data is shifted to the right, but when H'<e, the data is shifted to the left. Now, the output of the forward/reverse control 71141 circuit (125) is from 5L” to “H”
Due to this change, the shift direction of the ring counter (114) changes. That is, in the motor (M) shown in FIG. 2, the first coil (Ll) and the second coil (L
The phase of 2) is reversed, and the second coil (L2) leads the first coil (Ll) by τ. As a result, the stepping motor (M) starts to fully reverse, and begins to close the sector (3). To explain in more detail using the exposure diagram shown in FIG. 5, the counter (110) shows the number of pulses to fully drive the motor (M):
It is configured to count, and the next counter (111) t,
I, count 1- at the level divided by in in the above pulse
Since the output of the forward/reverse control circuit (125) can be reversed in minute steps, for example, within the second pulse (step) as indicated by the dotted line in the figure, the output of the forward/reverse control circuit (125) can be reversed. I can do it. As a result, it is possible to obtain the entire fine exposure amount of 1 for the exposure -64:Qt determined by the first pulse and Q++nq depending on the brightness, as shown by the dotted line in the figure. Also at this time, reset I/pulse generation circuit (104)
generates a reset pulse and counter (112)'!
i = reset for a very short time, and the arithmetic circuit (107) calculates the number of pulses required to open the sector fROM (109)
7 and write on the counter (110) again. After the counter (112) is released from the reset, it resumes full operation and outputs a signal with the same cycle as during the opening operation, which is input to the counter (IIO) and the ring counter (114). Now, the anti-nilling counter (114) returns to the position where the sector starts opening in order to reversely rotate the step motor (M). When the content of the counter (110) becomes 0, the output of the OR gate (120) becomes "L", and the inverter ('127) is fully valved and the NA'AND gate 1-
(126), but this NAND gate (1
The other input 1/(2/l) is "Since the HnV bell signal is input, the output of NAND game) (126) is"
L'', the AND gate (128) is shut off, and the counter (112) is completely stopped, so the step motor (M) is also stopped. With this, all exposure operations are completed, and the first The state returns to the figure, the release button is returned to its original position, and the power switch (not shown) is turned off.

Note that although a counter is used for counting in the above explanation, an adder and a register may be used instead of a counter. Not only the count 1c, but also the circuit itself, the architecture -v'cJ:v can be considered, and this is the essence of the present invention. In addition, once the subject brightness is converted into digital data, the ROM can be fully accessed, and the RO
The amount of rotation of the stepping motor is determined by the data notated by Mj7ζTsuru, but the relationship that the opening amount of the sector is constant V
If this is the case, the stepping motor can be directly controlled by photometry and LAD-converted digital data. Also, for the same reason, the mv subject to A/D conversion is logarithmically compressed -C
However, this is not always necessary. F yc, the present invention can be implemented without A/D conversion of the subject brightness. For example, the method of measuring brightness sound using a VC capacitor, CDS, and comparator as in a normal photometry circuit, and a capacitor VCC. Start charging via dsq and rotate the steering motor forward,
All you have to do is rotate the stepping motor in the opposite direction from the point where the compantor is reversed.

As explained above, depending on the value detected by the brightness detection circuit, it is possible to change and reverse the pulses that drive the motor as appropriate, so the exposure amount can be changed continuously, so the brightness of the subject is extremely low. Even in bright conditions,
It is possible to obtain exposure black with little inherent error, and since all sectors are controlled using a stepping motor, the exposure operation is performed simply by switch operation, so the mechanical adjustment between the winding mechanism and shutter mechanism is The technical effects are impressive, such as eliminating the need for extensive coordination, making V-Leads operations easier, and making it easier to set up camera sequences.

[Brief explanation of the drawing]

FIG. 1 shows the shutter mechanism of the embodiment of the present invention, and the second
Figure 1 shows the structure of the stepping motor used, Q'l, Figure 3 is the circuit diagram for fully driving the stepping motor during construction, Figure 4 is the conventional exposure line diagram, and Figure 5 is the exposure diagram of the proposed method. A diagram is shown. In the figure, (3)...Sector, (4)...Sector ring, (M)...Stepping motor, (
17,,18)...Stator, (22)...Low coupling, (101)...Oscillation circuit, (1o2)...Brightness detection circuit, (110,111')...Counter,
(112)...Pulse signal generation circuit, (,113)...
...Frequency divider circuit, (114) ...Ring counter, (
125)...Forward and reverse rotation control circuit. Agent above [K1 indentation (B)] Procedural amendment (spontaneous) Patent Application No. 164546 of 1982 2, Title of invention program 7 Yatsuta 3, Specification of person making the amendment 11 Name of invention program Shutter 2, Claims A shutter mechanism equipped with a sector that forms a lens aperture, a step motor that can rotate forward and backward to open and close the sector, and calculates the exposure amount according to the subject's fI of 11 degrees. circuit means for outputting the number of rotational steps and interpolation amount of the step motor in accordance with the exposure amount; circuit means for outputting the rotational step number and interpolation amount of the step motor in accordance with the exposure amount; and the circuit means for rotating the motor in a forward direction and a reverse direction in correspondence with the step order. The rotation direction is changed to 1 when a time corresponding to the interpolation amount has elapsed from the time when the last pulse was output from the motor drive means and the drive means. , lJ and circuit means for driving the shutter in reverse. 3. Detailed Description of the Invention (Technical Field) The present invention relates to a program shutter, and more specifically, to a program shank in which the opening and closing operations of shutter blades are performed by a step motor. (Prior art) The opening and closing operations of the shutter blades are programmed using a step motor.The shutter is operated by manually applying drive pulses with a fixed period to the step motor using the release operation '1' to rotate the motor in the forward direction, thereby gradually changing sectors. / 1 river, the stencil rotated l' corresponding to the exposure amount! The phase of the drive pulse is switched by Ij and I, and the step motor is rotated to close the sector, thereby obtaining It- light at an appropriate IF. By the way, the maximum rotational speed of the step motor used in this shutter is as low as 500 to 1000 pulses/second, so there is a restriction on the minimum time required for one step to rotate. This has the disadvantage of causing a large error in exposure and not being able to obtain an optimal 1D optical stamp, which is a major problem in the current situation where films are becoming more sensitive. Of course, such problems can be solved by reducing the slope of the opening line of the shank or by using a step motor with a high rotation speed, but the mechanism becomes complicated and
This brings about new problems such as increased motor costs. (Objective) In view of the above-mentioned problems, an object of the present invention is to provide a programmable shutter that not only can reduce the exposure time at short seconds, but also can obtain exposure steps with fine grains. do. (Structure) In other words, the present invention is characterized by determining the number of rotational steps and interpolation amount of the step motor according to the exposure amount depending on the intensity of the subject, and when the shutter is opened, the step motor Steer the sector by driving pulses.
The main feature is that the rotation direction is switched when a time corresponding to the amount of interpolation has elapsed from the time when the final step drive pulse is outputted, and interpolation is performed by subdividing the steps between steps. Therefore, an explanation will be given based on an example in which the details of the unknown are omitted in the figure below. FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes a plywood board to which a front plate 2 for positioning the lens is attached to the aperture, and a sector chamber 3 is formed between the front plate 2 and the front plate 2. and fill sectors 4 and 4 with ψj° (lJ). 5 is sector 4.
4 is a sector ring that is driven to open and close, and a degree-determining portion 5a formed on the outer periphery. The rotation F+-iζ is restricted by the pin 6 implanted in the front plate 1 and the front plate 1, and levorotation is imparted by the nose 7 hung between the front plate 1 and the outer circumference of the front plate 2. It is mounted by a heavy wheel 8 for rotation. Place two wooden sector pins 5 on the plywood side surface of this sector ring 5 symmetrically with respect to the optical axis.
b, 5b are planted and engaged with the two sectors 4.4, respectively, and a mountain portion 5C is formed on the outer periphery to be connected to the pinion 21 of the step motor 11, which will be described later, via the wheel train 9.10. ing. FIG. 2 shows the above-mentioned forward-reversible step motor 11.
12 is a motor base plate, which has a mounting hole 1 that engages with the base plate 1 of the shutter body with a screw.
3 are bored, and two stators 16.16 are disposed facing each other in the vertical direction by pillars 14.14 and guide bins 15.15 planted on the surface, and the motor h plate 17 is mounted on the pillars 14.14. 14 with screws 18 and 18, and a rotor 19 made of a permanent magnet is attached to the motor base plate 12 and
The rotating shaft 20 is protruded from the - side, and the transmission gears 21 are arranged in several rows. In addition, the symbols , L2 in the figure are stators 16 and 16, respectively.
2 shows the wound pIfJl and the second drive coil. Next, a control device that is a characteristic feature of the present invention will be explained. FIG. 3 shows an embodiment of the device for controlling the shutter mechanism described above, in which reference numeral 31 detects the operation of a switch 32 that is linked to a release button (not shown) and outputs a photometry start pulse. A photometry start pulse generation circuit 34 steps down the signal from the reference pulse oscillator 33 equipped with a crystal oscillator at a predetermined ratio to generate a luminance data clock CKI, a step drive clock CK2, and this clock CK2. The interpolation clock C has a higher frequency compared to
The frequency dividing circuit 35 that generates K3 is a 11 degree detection circuit that outputs a clock CKL according to the brightness of the subject, and is started by the manual input of the photometry start pulse, and is activated by a light receiving element such as a CdS installed in the camera body. 49 is logarithmically compressed, and a luminance data clock CKI is output to a counter circuit 36, which will be described later, for a time proportional to this value. 36 is the aforementioned counter circuit that is cleared by the photometry start pulse and simultaneously counts and holds the luminance data clock CKI from the 11 degree detection circuit 35; 37 is the exposure 1-! The arithmetic circuit is configured to calculate the optimum exposure amount based on the film sensitivity information set by the switch group 38 and the contents of the counter circuit 36. Reference numeral 39 denotes a one-data storage circuit that stores step motor drive data corresponding to the exposure amount in advance. It is configured to output interpolated data obtained by subdividing steps. 40 is a step drive pulse generation circuit that sets the rotation speed per step of the step motor, and a switch 41 that is linked to the release button.
It is configured to output a step drive pulse Ps of a constant period based on the step drive clock CK2 inputted through the gate G, by the operation of the gate G. 42 is a presettable first control unit that controls step drive.
The down counter presets the step number from the exposure data storage circuit 39, and the step drive pulse Ps
The counter is sequentially decremented by 1, and when the counter contents become zero, a signal is output from the output G2. 43 is a preseller l- for controlling interpolation drive.
++ (gate G that opens when the content of the first down counter 42 becomes zero by presetting interpolated data from the exposure data storage circuit 39 with a second down counter that is capable of
3 is sequentially subtracted by 1 using the interpolation clock CK3, and when the content becomes 0, a signal is output from the output gate G3. 44 is a forward/reverse+8)J detection circuit which detects the 11f point where the contents of the first counter 42 and the second counter 43 both become zero, outputs an inverted signal, and exposes! 1; Performance 1? circuit 37
It is possible to read the exposure data from again and preset the number of steps to the first counter 42, to operate the step drive pulse generation circuit 40 again via the reset pulse generation circuit 45, or to operate the pulse motor drive circuit described later. 46 is configured to switch the direction of pulse movement. 46 is the aforementioned pulse motor drive circuit, and each time a pulse signal is input manually, the terminal for outputting the signal moves one by one to the adjacent one.
It consists of a so-called ring counter. The stepping motor 11 is inputted with a driving pulse and an inverted signal, and the moving direction of the pulse from the output terminals Ql-Q4 is switched by the inverting motor 11. 4111 is configured to rotate in the direction or in the opposite direction. In addition, the reference numeral 47 in the figure amplifies the signal from the drive circuit 46 and outputs the stator coils L, L2 of the step motor 11.
The drive circuit that supplies power to the is shown. Next, the operation of the apparatus configured as described above will be explained based on the waveform diagram shown in FIG. After turning on the power switch (not shown), press the release button on the camera body to the first depressed position.
The switch 32 is turned on and the counter circuit 36 is cleared, and at the same time, the luminance detection circuit 35 outputs a number of clocks CK corresponding to the subject luminance and is stored in the counter circuit 36. The exposure amount calculation circuit 37 calculates an appropriate exposure amount determined based on the contents of the counter circuit 36 and the film sensitivity, and outputs it to the exposure amount data storage circuit 39. The exposure amount data storage circuit 39 receives the exposure amount from the arithmetic operation circuit 37 and stores the number of steps that can cover sector rotation 4) and interpolation data for correcting this step rotation. and output to the second down counters 42 and 43 to set the exposure amount. When you have finished setting the exposure, press the release button to the second position.
When pushed to the position, the switch 41 is turned on, the step drive pulse generation circuit 40 is activated, and the step drive pulse Ps is output to the first counter circuit 42 and the above-mentioned pulse motor drive circuit 46. As a result, each time one step drive pulse is input, the step motor 11 rotates two steps in the positive direction and begins to open the sector 4.4 (FIG. 1), and at the same time, the first down counter 42 turns 1. It is subtracted by one by one. In this way, the first counter 42
When a step drive pulse of 1 is output for the number preset in
- Output a signal from G2, open the gate G3, and input the interpolation amount clock CK3 to the second down counter 43. As a result, the rotation continues while subdividing the two steps by the pulse interval μm1 of the interpolation clock CK3. When the number of interpolation clocks CK3 matches the preset number of the second counter 43, a signal is output from the gate G4 to activate the forward/reverse switching circuit 44 to output an inverted signal, and the arithmetic circuit 3
Exposure from 7,! First, what exposure amount is output again to the data storage circuit 39 to preset the number of steps in the first counter 42, and at the same time, the direction of pulse movement of the pulse motor drive circuit 46 is changed, so that the pulse with the short pulse width output just before is The phase is switched and output, and the step motor 11 is forcibly reversed. Due to this reverse rotation of the pulse motor, the sector 4.4 gradually begins to close and rotates step by step every time a drive pulse is input, and when the first counter 42 reaches zero, the gate G is closed and the step drive pulse is input. At the same time, sector 4.4 returns to its original position and the optical path is closed. When the above operations are completed, the release button returns to its original position, and the power switch (not shown) is turned off.
F and prepare for the next shot. Needless to say, since the correction amount becomes zero at a location where the step rotation position of the step motor and the exposure amount match, it is possible to directly shift to reverse driving without performing interpolation. FIG. 5 shows a second embodiment of the present invention, in which a capacitor 48b is charged with a constant flow through a transistor 48a which is turned off by a pulse from a photometry start pulse generating circuit 31. A diode 48c for logarithmic compression connected in parallel with a light-receiving element 49 such as charging, heavy pressure, and CaS.
When the switch 32 moves 1'1, the terminal 48e is opened to output the clock CKI from the frequency divider circuit 34 to the counter circuit 36, and the inversion of the comparator 48d causes the gate 48e to be opened. By closing the clock CKI and increasing the output of the clock CKI by 4':'+l-, digitized subject power saving data is output. In addition, l 1! In the JS embodiment, rotation step number data and interpolation -r- data corresponding to exposure J,1 are used and stored in the storage means in advance, but the performance '! , Tsu'0
Steps, for example using a puncture circuit, exposure! 11: Dividend, l
The same operation is performed by using the exposure amount per step rotation as a divisor, the quotient is used as step number data, and the remainder is used as interpolation amount data. (Effects) As explained above, according to the present invention, exposure! The number of rotational steps of the step motor corresponding to Since the camera is driven in steps in the opposite direction, it takes advantage of the fact that a shank-charging mechanism is not required and the release operation can be made lighter, while also allowing fine-grained control of the exposure amount regardless of the step-to-step movement speed of the step motor. In particular, exposure accuracy at short seconds can be dramatically improved. 4. Brief description of the drawings Figures 1 (a) and (b) are a plan view and a sectional view showing an example of a shutter mechanism to which the present invention is applied;
(B) is a plan view and a sectional view showing an example of a step motor used in the above device, and FIG. 3 is a block diagram of a circuit constituting an embodiment of the control device according to the present invention that operates the above shutter mechanism. 4 is an explanatory diagram showing the operation of the above device, and FIG. 5 is a block diagram of a circuit constituting another embodiment of the control device according to the present invention. 4.4...Sector 11...Noculus motor LI L2...Drive coil 46...Pulse motor drive circuit Applicant: Seiko Koki Co., Ltd. (A), 11 (B) Skull (A) 2 Wards

Claims (1)

[Claims] (1) A plurality of sectors that form the entire lens aperture, and a stepping motor that can be controlled to rotate in forward and reverse directions;
A brightness detection circuit for detecting subject brightness, a time reference signal oscillator, a frequency divider connected to the oscillator; a pulse signal generator for generating a pulse signal for driving the stepping motor; and a pulse direction converter for controlling the rotational direction of the stepping motor; The program shutter is characterized in that the pulse train generated by the pulse signal generator is used as information for the subject brightness detection circuit, and the pulse width is arbitrarily changed to change the pulse direction. (2. In the device described in claim (1), an AD converter' further connected to the luminance detection circuit and the branching unit)
ff: A program shutter characterized in that the AD converter is guided to a counter, and the counter controls all of the pulse direction converters. (3) Il'y-Claims (In the thing described in 2), the above-mentioned counter is a counter capable of counting in response to the pulses of the above-mentioned cycle signal generator and an output numerical value and phase counter of the subject brightness detection circuit. A program shutter characterized by inputting a difference from an input numerical value into a fine counter, and fully controlling the pulse direction converter using the coarse counter and the fine counter.