JP2759662B2 - Camera with motor-driven shutter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera with a motor-driven shutter, and more particularly to a camera that corrects the operating characteristics of a shutter mechanism using a motor.

(Prior Art) A program shutter for opening and closing shutter blades by, for example, a step motor is operated by inputting a drive pulse having a certain cycle to the step motor by operating a release button to rotate the motor forward to gradually move the sector. The phase of the driving pulse is switched at the time of opening and performing the step rotation corresponding to the exposure amount, and the step motor is reversed to close the sector to obtain an appropriate exposure.

By the way, in the shutter in which the opening and closing operation of the sector is performed by such a step motor, the load of each part is applied to the step motor in the process of opening the sector, and the inertia at the time of the movement of each component or the hammer-eye error of each component. In addition, there has been a problem that the variation of the aperture diameter with the passage of time in the opening process becomes non-uniform, and accurate exposure amount control cannot be performed. In particular, there is a problem in a camera having interchangeable lenses, since characteristics including a motor differ for each interchangeable lens.

(Purpose) The present invention has been made in view of the above problems, and has an object to provide a program shutter in which a shutter mechanism is changed or a change in the aperture diameter of a sector in the opening and closing process is uniform even for a camera whose lens can be exchanged. Aim.

(Means for Solving the Problems) That is, in order to achieve the above object, the present invention provides a designating means for storing and designating opening / closing operation characteristics of a shutter mechanism including a sector and a motor. By providing a motor drive circuit having a plurality of corresponding data, the designating means designates one of the plurality of data and sets a pulse width in synchronization with an operation characteristic of a shutter mechanism. By driving the stepping motor, the change in the opening diameter is made uniform.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings applied to a camera having an interchangeable lens. In FIGS. 1 and 2 showing a shutter built in the interchangeable lens, M is a rotor R composed of a permanent magnet rotatably supported by the shaft 1 and multipolarly magnetized in the radial direction, and two stators S having poles opposed to the pole magnets of the rotor R.
A and SB, and coils LA and LB fitted to the respective stators, and the coils are connected to the control circuit shown in FIG.

Each of the stators SA and SB is fixed to a substrate of the motor M by mounting shafts SA1 and SB1, and a magnetic pole portion facing the rotor R is
The position is regulated by the pins SA2 and SB2, respectively.

A shutter opening OA is formed in the center of the substrate of the motor M, a shaft 1 of the rotor R extends downward through the substrate, and a gear 2 is press-fitted and fixed at a tip end thereof. It is formed in a circle around the opening OA.

A shutter base plate 3 shown in FIG. 2 is attached to the back surface of the substrate of the motor M, and between them, shutter blades 4 and 5 are arranged and an operation area thereof is defined.

The shutter blade 4 is rotatably supported on a fixed shaft 4a,
The shutter blade 5 is rotatably supported on a fixed shaft 5a, and has an image edge portion 5a forming an aperture opening together with the image edge portion 4b, and an operation groove. The fixed shafts 4a and 5a are disposed at positions facing the gear 2 with the shutter opening OA interposed therebetween.

The opening / closing lever 6 is supported on the back surface of the shutter base plate 3 so as to be rotatable around a fixed shaft 5a.
The pins 6b fitted into the operation grooves 4c and 5c and further extending upward extend toward the motor M, protrude above the motor substrate, and engage with the switch contact pieces SW.

The switch contact piece SW is configured as a pair of switches by contacting the contact piece pin SP, and is connected to a control circuit described later.

Next, the operation method will be described. When a control circuit shown in FIG. 3 described later is operated, a drive signal of a bipolar drive two-phase excitation system is output to the two coils LA and LB, and the stators SA and SB are driven. Is excited, the rotor R turns left, and the shutter blade 5 meshing with the tooth portion 5d turns right around the axis 5a by the gear 2, and at this time, the pin 6a is actuated by the groove 5c,
Turn right with the open / close lever 6.

Accordingly, the shutter blade 4 is rotated leftward around the axis 4a by being actuated by the pin 6a in the groove 4c.

When the left turning of the rotor R continues, the shutter opening is gradually opened by the image edges 4b and 5b of the shutter blades 4 and 5, and the exposure is controlled by the combination of the aperture and the exposure time, and when the desired value is reached. A drive signal for reversing the rotor R is output to the two coils LA and LB by the control circuit shown in FIG. 3, so that the rotor R instantaneously reverses, and the gear 2 moves the shutter blade 5 around the axis 5a. Then, the shutter opening OA is closed together with the shutter blade 4.

Here, when the opening / closing lever 6 turns to the right, the switch contact piece SW is operated by the pin 6b, and the control circuit starts counting to calculate the exposure amount.

Next, the configuration of the shutter on the interchangeable lens side, which is the gist of the present invention, will be described.

In FIG. 2, a data designating unit D outputs a signal to a control circuit shown in FIG. 3 based on a shutter mechanism built in the interchangeable lens, that is, the operation characteristics of each component shown in FIGS. The data is specified according to the characteristics of the individual lenses (the characteristics are different among individuals even for the same model, and the characteristics are different depending on the lens aperture diameter, motor size, and the like).

 The operation characteristics will be described in detail with reference to FIG.

FIG. 3 shows an embodiment of the control device.
Is used to generate a clock Ck1, a step driving clock Ck2, Ck3, and an interpolation clock Ck4 for dividing a signal from the reference pulse oscillator 21 having a crystal oscillator at a predetermined ratio and digitizing photometric data. A peripheral circuit 23 is a luminance detecting circuit, and a charging voltage from a capacitor 23b charged with a constant current via a transistor 23a which is turned on and off by a switch 24 linked to a release button (not shown), and a light receiving element 25 such as Cds. Logarithmic compression diode 23 connected in series to
The terminal voltage of c is compared by the comparator 24d, and the switch
At the time of operation of the gate 24, the gate 24e is opened to output the clock Ck1 to the counter circuit 26 to be described later, and the gate 24e is closed by inversion of the comparator 24d to stop the output of the clock Ck1 to digitize and output the subject brightness. Is configured. Reference numeral 26 denotes the above-described counter circuit, which is cleared by the operation of a switch, and at the same time, counts subject brightness data from the brightness detection circuit 23 and outputs the content.

Reference numeral 27 denotes an exposure data storage circuit storing step motor drive data corresponding to the object brightness possessed, and stores data on the number of steps to rotate the step motor M and interpolation data for correcting an exposure error caused by the number of steps. It is configured so that it can be accessed according to the count content of the counter circuit 26. Further, the storage circuit 27 stores a plurality of types of data that determine the pulse width of the drive pulse in each step in accordance with the opening / closing operation characteristics of the shutter mechanism, and the optimal data specified by each interchangeable lens is the counter 31a or the counter 31a. 31b
Is read immediately before each step. 28
Is a forward step drive pulse generating circuit, which can drive the step motor M in the forward direction against the load of the position regulating spring SW (FIG. 1) of the shutter mechanism.
Is generated based on the step drive clock Ck2, and the output of the pulse is stopped by inversion of the forward / reverse switching circuit 32 described later. Reference numeral 29 denotes a reverse step drive pulse generation circuit which outputs pulses Q1... Qn (not shown) for driving the step motor M in the reverse direction based on the step drive Ck3 from the time when the forward / reverse switching circuit 32 reverses. Is configured. Numeral 30 denotes a pulse switching circuit. An AND gate receives pulses Pn and Qn from the pulse generating circuits 28 and 29 at one end, and a signal from the forward / reverse switching circuit 32 and a signal obtained by inverting the signal at the other end. 30a and 30b, and an OR gate 30c connected to the AND gates 30a and 30b. The OR gate 30c is configured to select and output a pulse Pn during normal rotation and a pulse Qn during reverse rotation. Reference numeral 31 denotes a rotation mode switching counter, which is a presettable first down counter 31a formed by cascading flip-flops F1 to F3, and a second presettable second counter formed by cascading flip-flops F4 to F6. Down counter 31
The first counter 31a presets the number of steps from the exposure amount data storage circuit 27 by selecting data corresponding to the interchangeable lens when the step motor M starts normal rotation and when the step motor M reverses, and sets the pulses Pn, A signal is output from the output gate G2 when the content of the counter becomes zero after being decremented by one by Qn. On the other hand, the second counter 31b provides an exposure amount data storage circuit 27 when the step motor M starts normal rotation. Similarly, the interpolation amount data is similarly preset by selecting data corresponding to the interchangeable lens, and when the content of the first counter 31a becomes zero, it is subtracted by one by the interpolation clock Ck4, and the content becomes zero. And outputs a signal from the output gate G4. In addition, the above P1 to Pn,
The data that determines the pulse width of each pulse of Q1 to Qn is a counter
The outputs of 31a and 31b are transmitted from the storage circuit 27 to the forward step drive pulse generation circuit 28 or the reverse direction pulse drive pulse generation circuit 29 immediately before the generation of each pulse.

A forward / reverse switching circuit 32 latches a signal from the mode switching counter circuit 31 and operates the pulse switching circuit 30 to switch from the pulse Pn to the pulse Qn, and at the same time, switches a pulse moving direction of a step motor driving circuit 33 described later. , 33
Is a stepping motor drive circuit as described above, which comprises a so-called ring counter in which a signal output terminal shifts one by one every time a pulse signal is input, and a pulse switching circuit
A pulse is input from 30 and the direction of movement of the pulse is switched by a pulse signal based on a signal from the forward / reverse switching circuit 32 to rotate the step motor M in the forward or reverse direction.

The switch constituted by the switch contact SW and the contact pin Sp operates as described with reference to FIG. 1, and the switch discriminating circuit 37 determines whether or not the shutter is in the normal state, or starts from the normal state. It is determined whether or not the setting has been performed, and is output to the set signal generation circuit 35.

In the drawing, reference numeral 34 denotes a second switch for resetting the rotation mode switching counter 31 and the forward / reverse switching circuit by operating the release button, and 35 denotes a set signal for setting the pulse generating circuits 28 and 29 by operating the switch 34. Generator circuit, 36
Shows drive circuits that amplify signals from the output terminals R1 to R4 of the step motor drive circuit 33 and supply power to the excitation coils LA and LB of the step motor M.

The signal terminals from the interchangeable lens shown in FIGS. 1 and 2 correspond to coils LA, LB, switch SW, and data designating means D, respectively, as 1a-1a, 1b-1b, Sw-Sp, and Ds. And a connection portion between the camera body and the camera body via a signal transmission contact.

Next, the operation of the device configured as described above will be described with reference to the timing chart shown in FIG.

After turning on a power switch (not shown), when the release button of the camera body is pressed to the first position, the first switch 24 is turned on, and the subject luminance detection circuit 23 is activated.
The number of clocks Ck1 corresponding to the subject luminance is output, and the counter 26 stores the luminance data. The exposure amount data storage circuit 27 stores the number of steps capable of covering the exposure amount based on the luminance data of the counter 26 and the interpolation amount for correcting the step rotation in the first mode of the rotation mode switching counter circuit 31. And presets it to the down counter 31a and the second down counter 31b, and sets exposure data corresponding to the subject brightness.

When the above setting is completed, when the release button is pushed down to the second position, the switch 34 is turned on, the rotation mode switching counter 31 and the forward / reverse switching circuit 32 are reset, and at the same time, the forward step driving pulse generating circuit 28 The reverse step drive pulse generation circuit 29 operates to generate the pulse Pn and the pulse Qn. The pulse switching circuit 30 selects the pulse Pn and outputs the first counter 31a of the rotation mode switching counter 31.
And outputs it to the step motor drive circuit 33. Each time one pulse Pn is input, the step motor M receives a spring SW (first
Since the pulse width data for correcting the inertia of the shutter mechanism and the backlash caused by squeezing is output from the storage circuit 27 to the pulse generation circuit 28 against the load of FIG.
By rotating in the forward direction one step at a time, sectors 4 and 5 begin to open in the relationship shown by the solid line in FIG.
Is decremented by one.

That is, when the shutter mechanism is driven by a pulse Pn having a constant period shown by a broken line in FIG. 4B, a hunting phenomenon occurs due to the operating characteristics of the shutter mechanism as shown by the broken line in FIG. Although the change in aperture becomes non-uniform, in the present invention, the storage circuit 27 specifies a pulse Pn having a width set in advance according to the operating characteristics of each interchangeable lens as shown by the solid line in FIG. The sectors 4 and 5 operate in the relationship shown by the solid line in a).

That is, the pulse P5 corresponding to the interchangeable lens of the embodiment is
In order to make the non-uniform aperture diameter shown by the broken line in FIG. 4 (a) into a uniform aperture diameter shown by the solid line, the pulse width is shortened and the pulse of P6 is output earlier. 4 and 5 are rapidly moved, and the pulse P7 is also increased in pulse width so that the non-uniform aperture diameter indicated by the broken line in FIG. 4 (a) becomes a uniform aperture diameter indicated by the solid line. , P8 are delayed and output, so that the sectors 4 and 5 move slowly in the direction of arrow B. The data of the above A and B are
Since it differs depending on the interchangeable lens, the storage circuit 17 stores a plurality of types of combination data and outputs a designated value designated by the data designating unit D of each interchangeable lens.

When the preset number of pulses Pn are input to the first down counter 31a in this manner, the interpolation is performed from the gate G3 to the second counter 31b while the step motor M is rotating toward the final step. Clock Ck4 is input.

When a clock Ck4 that matches the preset number of the second counter 31b is input, the forward / reverse switching circuit 32 is inverted to output a pulse Qn (not shown) from the pulse switching circuit 30, and at the same time, the step motor driving circuit 33 is rotated in reverse. Switch to drive side. As a result, a pulse Q2 (not shown) from the pulse switching circuit 30 is input to the drive circuit 33, the step motor M is forcibly driven in the reverse direction, and the sector is driven by the left turning force stored in the position control spring SW. Cooperating with each other, step rotation is performed in the opposite direction in synchronization with the pulse Qn, and the sectors 4 and 5 are closed.

Counter for pulse Qn as well as for positive rotation
When the pulse width synchronized with the operation characteristic is designated by the output of 31b and the content of the first counter 31a becomes zero again, the sectors 4, 5 return to their original positions and close the optical path.

When the above operation is completed, the AND gate 30b operates via the NAND gate G5 according to the output signal of the forward / reverse switching circuit 32 and the output inversion signal of the OR gate G2, and the reverse step drive pulse is output from the OR gate 30c. Therefore, the motor 12 stops, the release button returns to the original position, and the switch 34 opens to prepare for the next photographing.

In the above embodiment, the storage circuit provided in the camera body
27, a plurality of types of data are stored in advance, and one of the data on the camera body side is designated by the data designating means D of each interchangeable lens. Or all of the data necessary for the correction of the opening and closing characteristics may be provided. By doing so, an interchangeable lens (shutter mechanism) with any characteristics in the future
Even if is manufactured, correct exposure operation can be performed by correcting the data on the interchangeable lens side without affecting the existing camera body at all.

Further, in the above-described embodiment, the camera in which the shutter is built in the interchangeable lens has been described. However, the difference in the opening diameter of the shutter blades, the difference in the motor and other mechanisms, etc. can be applied to the normal camera shutter in which the lens is not replaced. A shutter that performs an accurate operation can be constituted by a single drive circuit for correcting the opening / closing operation characteristics caused by the above.

In the above embodiment, the step motor driven shutter has been described, but an ultrasonic motor or another motor may be used.

(Effects) As described above, according to the present invention, the change in the aperture diameter with respect to the elapsed time of the sector becomes uniform by correcting the pulse with the pulse width synchronized with the operation characteristics of various shutter mechanisms, and the smoothness is achieved. When the shutter mechanism is changed or the lens is changed, a single drive circuit can be used to control the exposure amount with high accuracy for the subject brightness. Flash tuning is possible with an appropriate aperture diameter corresponding to the distance, and high-precision control is possible.

Further, by incorporating one drive circuit into the camera body and converting only the waveform data corresponding to each interchangeable lens, appropriate exposure control can be performed for any lens.

[Brief description of the drawings]

FIG. 1 is a plan view of a step motor used in the present invention,
FIG. 2 is a plan view showing an embodiment of a shutter mechanism, FIG. 3 is an explanatory diagram of an apparatus constituting an embodiment of a shutter control circuit according to the present invention, and FIG. 4 is an operation diagram of the shutter. M: Step motor (motor) R: Rotor 2: Gear 4, 5, Shutter blade 6: Open / close lever D: Data designation means (correction means) 23: Subject luminance detection circuit 27: Exposure amount Data storage circuit 28 forward motor drive pulse generation circuit 29 reverse motor drive pulse generation circuit 30 pulse switching circuit 31 rotation mode switching counter 33 motor drive circuit

Claims (2)

(57) [Claims] 1. A shutter mechanism having a forward / reverse rotatable motor for driving a sector for opening / closing a lens opening, a designating means for storing opening / closing operation characteristics of the shutter mechanism, and a pulse number corresponding to subject brightness Storage means for storing motor drive data such as and pulse width data for each pulse of a plurality of types of the motor drive data, and a drive circuit for driving the motor based on data from the storage means, The designating means designates any one of the plurality of types of pulse width data in the storage means based on the stored opening / closing operation characteristics, and causes the motor to drive the motor with the opening / closing operation characteristics corrected. A camera with a motor-driven shutter. 2. A shutter mechanism comprising a camera body and an interchangeable lens attached to and detached from the camera body, the interchangeable lens having a forward and reverse rotatable motor for driving a sector for opening and closing a lens opening, and the shutter. Specifying means for storing the opening / closing operation characteristics of the mechanism; wherein the camera body has motor drive data such as the number of pulses corresponding to the subject brightness and a plurality of types of pulse widths for each pulse of the motor drive data. Storage means for storing data and
A drive circuit that drives the motor based on the data from the storage unit; and the designation unit is any of the plurality of types of pulse width data in the storage unit based on the stored opening / closing operation characteristics. A camera with a motor-driven shutter, wherein the camera is operated by correcting the opening / closing operation characteristic by designating one of the two.