JP4505048B2 - Camera shutter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera shutter, usually referred to as a lens shutter, that opens and closes a circular exposure opening by reciprocating operation of a shutter blade.
[0002]
[Prior art]
Recent cameras are becoming more and more motorized, and in the case of lens shutters, the number of shutter blades that are opened and closed by a motor has increased. In addition to the stepping motor, the motor used in that case is a current-controlled motor in which the rotation direction of the permanent magnet rotor is determined by the direction of current application and can rotate only within a predetermined angle range. Is used. The current control motor is often referred to as a moving magnet type motor in the industry, and its driving force is inferior to that of a stepping motor. However, the control system is simple and suitable for cost reduction and miniaturization. There is a feature that. Various configurations have also been proposed for this type of motor when used in a shutter, and typical ones are described in Japanese Utility Model Publication No. 6-24815 and Japanese Patent Application Laid-Open No. 11-98800. ing.
[0003]
In addition, since this type of motor does not have a large driving force, the opening / closing operation of the shutter blades is very easily affected by manufacturing quality variations (individual differences) such as the permanent magnet rotor and the shutter blades. Therefore, as described in the above Japanese Utility Model Publication No. 6-24815, an adjustment circuit is provided in each shutter control system, and the current and voltage supplied to the motor drive circuit are adjusted in the manufacturing process. In addition, it is known that the opening operation time (rise time) from the pinhole of the shutter blade to the full opening is approximated to the design standard (individual difference adjustment).
[0004]
Furthermore, when this type of motor is used to open and close the shutter blades, at least from the start of the opening operation to the start of the closing operation, current is not continuously supplied in a predetermined direction but is intermittently supplied. It is known to provide an automatic supply. The reason for adopting such a control method is that, although the driving force of this type of motor is not so large, if the load (shutter blades, etc.) is small due to the downsizing of the shutter, it is practically used. This is because there is a case where it is possible to endure, and it is possible to reduce power consumption by doing so. The present invention relates to a camera shutter that uses a current control motor and adopts such a control method.
[0005]
[Problems to be solved by the invention]
By the way, since the moving magnet type motor has a small driving force as compared with the stepping motor, the startability of the shutter blade is slightly difficult. This is the same even when a control method is adopted in which a current in a predetermined direction is intermittently supplied as in the shutter that is the subject of the present invention. Therefore, even if it is caused by extremely fine dust or dirt, or even by a slight fluctuation of the applied voltage, it cannot be started stably and smoothly, and as described above, the individual difference of the rise time can be adjusted at the time of production. Even if it is performed, exposure control may not be performed properly.
[0006]
In addition, there is another problem. In the case of a shutter using this type of motor, it is usual to maintain the closed state of the shutter blades when the camera is not used by utilizing the magnetic force of the permanent magnet of the rotor. That is, a magnetic member is arranged at a position facing the circumferential surface of the rotor so that an attractive force is generated between the rotor and the attractive force even when the motor is in a non-energized state. the rotor, allowed to act to rotate in a direction to close the shutter blades, which are Unisa allowed by you prevented by a predetermined stopper, and so as to maintain the closed state. Therefore, in such a case, the opening operation of the shutter blades is performed against the suction force, and thus the poor startability becomes a problem.
[0007]
In such a case, it is possible to prevent at least the rise time from being affected by increasing the run-up distance from when the shutter blade starts to open until it becomes a pinhole. Since the shutter is basically based on the premise that the shutter blades are made small, the run-up distance cannot be increased as such. Therefore, it is necessary to temporarily increase the driving force of the motor only during the run-up period, but how to make it possible becomes a problem. Even if it is possible to cope with the startability during the run-up period, the current is basically supplied intermittently, so that it is easily influenced by fluctuations in the power supply voltage. Therefore, it is necessary to adjust the rise time automatically so as not to be affected by fluctuations in the power supply voltage.
[0008]
The present invention has been made to solve such problems. The object of the present invention is to use the above-described current-controlled moving magnet type motor, and at least open the shutter blades. The shutter is configured to intermittently supply current in the same direction to the stator coil, and is not affected by fluctuations in the power supply voltage and has excellent startability without using a constant voltage circuit. It is an object of the present invention to provide an electric camera shutter that performs the above operation.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a camera shutter of the present invention comprises at least a first shutter blade and a second shutter blade each provided with a detected portion, and the first shutter blade and the second shutter blade. A plurality of shutter blades that open and close an exposure aperture by rotating the blades about different axes, and a plurality of operating positions are detected by detecting the detected portion during at least opening operation of the plurality of shutter blades. And a motor having a permanent magnet rotor that rotates by a predetermined angle range in different directions depending on the energization direction to the stator coil, and that causes the plurality of shutter blades to open and close, and the plurality of sheets A motor drive circuit for periodically supplying a current to the coil from the start of the opening operation of the shutter blade to at least the start of the closing operation; Activation control the energizing time per cycle to be supplied to the coil by chromatography motor drive circuit and the plurality of shutter blades are controlled separately by the time until a predetermined time and subsequent closing operation start before reaching the pinhole a motor control circuit and a control circuit to open the circuit, and the power supply has a voltage comparator circuit for comparing the voltage applied and the design reference voltage to the motor drive circuit, wherein the detecting means, before Symbol plurality In the middle of the opening operation of the shutter blade, the detected portion of the first shutter blade is first detected and a detection signal of the first position is output, and then the detected portion of the second shutter blade is detected. outputs a detection signal of the second position, the motor control circuit, the energizing time per said one period, to the first position and the detection signal of the second position from the detection means, the opening system To be able to adjust the time of a predetermined time after the opening operation of the plurality of shutter blades by the circuit, for the signal from the voltage comparator circuit, said plurality of shutters by the activation control circuit and the opening control circuit The total time from the start of the blade opening operation to the start of the closing operation can be adjusted.
In the camera shutter according to the present invention, if the predetermined time is a time until the detection means detects the first position, the detection signal is sent to the exposure time by the exposure control circuit. The count start signal can be used.
Further, in the camera shutter of the present invention, the motor control circuit periodically supplies current to the coil from the motor driving circuit even when the plurality of shutter blades are closed. includes a closed control circuit, said detection means, at least, the plurality of Oite in the middle of the closing operation of the shutter blade, the detection of the first to the third position by detecting a detected portion of the second shutter blade A signal is output, and then the detected portion of the first shutter blade is detected and a detection signal of the fourth position is output . In this case, the energization time per cycle is the opening operation of the plurality of shutter blades. In the same manner as in the case after the predetermined time, the detection can be made by the detection signals of the third position and the fourth position from the detection means and the signal from the voltage comparison circuit. Energization time of the adjusted and set to be always longer than the energization time during operation opening of the predetermined time after, while maintaining the opening and closing characteristic of the shutter blade suitably, it is possible to further reduce power consumption.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the illustrated examples. FIG. 1 is an explanatory diagram showing the configuration of the embodiment, and FIG. 2 is a timing chart for explaining the operation of the embodiment.
[0011]
First, the configuration of this embodiment will be described. In FIG. 1, a shutter base plate 1 has an opening 1a for restricting an exposure opening at the center thereof, and a blade chamber is formed between the shutter base plate 1 and an auxiliary base plate (not shown) arranged on the back side thereof. is doing. The auxiliary base plate also has a planar shape similar to that of the shutter base plate 1, and has an opening having the same shape as the opening 1a at a position overlapping the opening 1a. Further, the shutter base plate 1 is formed with a long hole 1b penetrating to the blade chamber and a window portion 1c, and two shafts 1d and 1e and two stoppers 1f and 1g are provided in the blade chamber. .
[0012]
Shutter blades 2 and 3 are arranged in the blade chamber. Among them, the shutter blade 2 is rotatably attached to the shaft 1d and has a long hole 2a, a detected portion 2b, and a tip portion 2c. The other shutter blade 3 is rotatably attached to the shaft 1e and has a long hole 3a, a detected portion 3b, and a tip portion 3c.
[0013]
On the surface side of the shutter base plate 1 (the subject side when incorporated in the camera), a photodetector and a current control motor are attached, but since their specific configurations are well known, In order not to make the drawings complicated and to understand only the basic configuration thereof, all are schematically shown. First, the photodetector of the present embodiment is a photo reflector 4, and the light emitting portion 4a and the light receiving portion 4b face the long hole 1b. And the light radiate | emitted from the light emission part 4a is reflected by the reflection means (not shown) provided in the blade chamber, and the light-receiving part 4b receives the reflected light.
[0014]
The motor of this embodiment has a permanent magnet rotor 5 magnetized in two poles, a stator coil 6, and a magnetic member 7 attached to the stator. A drive pin 5 a is provided at a position protruding from the radial direction 5. The drive pin 5 a is inserted into the blade chamber from the window portion 1 c and is fitted into the long holes 2 a and 3 a of the shutter blades 2 and 3. Depending on the rotation direction of the rotor 5, the shutter blade 5 a 2 and 3 are made to perform an opening operation or a closing operation.
[0015]
The motor control system further includes a power supply 8, a voltage comparison circuit 9, a motor control circuit 10, a motor drive circuit 11, an exposure control circuit 12, a detection circuit 13, and a photometry circuit 14. Yes. The motor control circuit 10 includes an activation control circuit 10a, an opening control circuit 10b, and a closing control circuit 10c. Further, the exposure control circuit 12 includes a subject light from the photometry circuit 14. In addition to the above information, information such as film sensitivity is input. Note that the arrows between the circuits in FIG. 1 indicate the information transmission direction.
[0016]
Next, the operation of this embodiment will be described with reference to the timing chart of FIG. FIG. 1 shows a closed state of the shutter. At this time, the coil 6 is not energized. However, the rotor 5 is given a force that rotates counterclockwise by the magnetic force of the permanent magnet. This is because the attractive force is exerted by the magnetic force of the permanent magnet so that the central portion around the S pole of the rotor 5 is located on the line connecting the rotation shaft of the rotor 5 and the magnetic member 7.
[0017]
The counterclockwise rotational force is transmitted to the shutter blades 2 and 3 via the drive pin 5a, and the shutter blade 2 is rotated counterclockwise on the shaft 1d, and the shutter blade 3 is rotated clockwise on the shaft 1e. However, the closed state is maintained by the tip portions 2c and 3c of the shutter blades 2 and 3 being in contact with the stoppers 1f and 1g. In order to prevent counterclockwise rotation applied to the rotor 5, the drive pin 5a may be brought into contact with the upper edge of the window portion 1c.
[0018]
Prior to shooting, when a power switch (not shown) is closed, the exposure control circuit 12 determines the exposure time (usually referred to as electrical time) according to information such as subject brightness and film sensitivity given from the photometry circuit 14. ) (Not the effective exposure time) can be started, and various warning circuits are activated. At this time, since the photoreflector 4 is also energized, the light emitted from the light emitting portion 4a is reflected by the reflecting means in the blade chamber, and the reflected light enters the light receiving portion 4b. In FIG. 2, such an incident state is referred to as “light transmission” for convenience, and a non-incident state is referred to as “light shielding”. It should be noted that the exposure time can be changed in accordance with the change in the subject brightness during photographing.
[0019]
Next, when the shutter is released, an automatic focusing device (not shown) operates to focus, and when the shutter is finished, a shutter blade opening operation start signal is given to the motor control circuit 10. Thus, the motor control circuit 10 outputs a signal from the start control circuit 10a to the motor drive circuit 11 in the initial stage of the opening operation, and then outputs a signal from the opening control circuit 10b before the pinhole state is reached. Further, when the shutter blades 2 and 3 are to be closed, a signal is output from the closing control circuit 10c to cause the shutter blades 2 and 3 to open and close.
[0020]
Therefore, the case where the present embodiment operates according to the design standard will be described with reference to FIG. 2, but before that, what is used as the design standard in the present embodiment will be described. First, the design reference voltage is set to a level at which proper exposure control may not be possible if the reference voltage is lower than the initial voltage of the power supply 8 and further lower. When the current is periodically supplied to the coil 6 at a predetermined short time at the reference voltage, the shutter blades 2 and 3 obtain the opening operation characteristic and the closing operation characteristic as shown in FIG. It is made to be able to. However, in that case, current is continuously supplied to the coil 6 only in the initial stage of the opening operation (time t1 in FIG. 2).
[0021]
When the shutter blade opening operation start signal is given to the motor control circuit 10 in such a design standard state, the motor control circuit 10 first outputs a signal from the start control circuit 10a to the motor drive circuit 11 and the coil 6 Is energized in the forward direction. Since this energization is continuously performed as described above, the rotor 5 starts to rotate well in the clockwise direction in FIG. 1, and some unexpected frictional force is applied to the shutter blades 2, 3 and the like. Even if there is a contact force or the like, the shutter pin 2 or 3 is preferably started to open by the drive pin 5a.
[0022]
When the shutter blades 2 and 3 are immediately before the opening 1a is brought into the pinhole state, that is, when a time t1 (hereinafter referred to as start-up time) elapses from the start of energization, the detected portion 2b of the shutter blade 2 is moved to the photo reflector. 4 light path is interrupted. When this interruption start signal is given from the detection circuit 13 to the exposure control circuit 12, the exposure control circuit 12 starts counting the exposure time and simultaneously gives the start signal to the motor control circuit 10. However, the signal to the motor control circuit 10 may be given directly from the detection circuit 13. When such a signal is given, the motor control circuit 10 gives a signal from the opening control circuit 10b to the motor drive circuit 11 instead of the activation control circuit 10a.
[0023]
Therefore, thereafter, the current is intermittently supplied to the coil 6 at a predetermined cycle, but the energization direction remains the forward direction. In FIG. 2, for convenience, half of one cycle is shown as energized. Then, when the shutter blades 2 and 3 are in a state where the opening 1a is substantially pinhole, the detected portion 2b of the shutter blade 2 releases the light shielding state of the photoreflector 4, and then the shutter blade 3 is covered. The detection unit 3b blocks the optical path of the photoreflector 4, and then the light shielding state is released immediately before the opening 1a is fully opened. The opening operation of the shutter blades 2 and 3 performed in this way is stopped after the drive pin 5a abuts against the lower edge of the window 1c after the opening 1a is fully opened. Thus, even if it will be in such a stop state, electricity supply with respect to the coil 6 is continued.
[0024]
Next, when the exposure control circuit 12 finishes counting the exposure time, an end signal is given to the motor control circuit 10. Thus, the motor control circuit 10 gives the motor drive circuit 11 a signal from the closing control circuit 10c instead of the opening control circuit 10b. For this reason, the coil 6 is energized in the reverse direction from the motor drive circuit 11 and the energization time per cycle is longer than half, so that the rotor 5 is faster than in the opening operation. And the opening 1 a is closed by the shutter blades 2 and 3. The rotation of the rotor 5 is stopped when the tip portions 2c, 3c of the shutter blades 2, 3 abut against the stoppers 1f, 1g.
[0025]
On the other hand, as described above, when a predetermined time has elapsed after the exposure end count signal is output from the exposure control circuit 12, the energization of the coil 6 is completely cut off, and the series of operations ends. In the process of closing the shutter blades 2 and 3, the photo reflector 4 can detect the positions of the shutter blades 2 and 3 at four locations. Comparing the end signals, the abnormal operation may be detected. As described above, a predetermined one position detection of the shutter blades 2 and 3 is performed without using the count end signal at the exposure time as a reference. When the predetermined time has elapsed after the operation, the power supply to the coil 6 may be completely cut off.
[0026]
Next, a method for adjusting the individual difference of the rise time performed at the time of manufacturing the present embodiment will be described. This individual difference adjustment is performed by applying the above-described reference voltage to the motor drive circuit 11. When the opening operation characteristics of the shutter blades 2 and 3 are not obtained as shown in FIG. 2 at the assembled stage, individual difference adjustment is performed. The time t2 shown in FIG. 2 is used as an evaluation criterion for the opening operation characteristic, in other words, as an evaluation criterion for the rise time. That is, the time from when the photoreflector 4 is shielded by the detected portion 2b of the shutter blade 2 until it is shielded again by the detected portion 3b of the shutter blade 3 is measured, and when the time is longer than t2. If the energization time per cycle controlled by the opening control circuit 10b is longer than the above half time and shorter than t2, the energization time per cycle is the above half time. The time t2 is adjusted to be shorter.
[0027]
Further, in the present embodiment, the individual difference adjustment of the fall time is performed in the same manner. That is, the evaluation criterion in that case is time t3, and the detected portion 2b of the shutter blade 2 from the time when the photoreflector 4 is once blocked by the detected portion 3b of the shutter blade 3 and then enters the light-transmitting state. 2 is measured after the light is interrupted once until the light-transmitting state is reached. If the time is longer than t3, the energization time per cycle controlled by the closing control circuit 10c is shown in FIG. The time is set to be longer than the time shown in FIG. 6B, and if it is shorter than t3, the time is shortened and the time t3 is adjusted. As a matter of course, in the case of the present embodiment, the individual difference adjusting function and the function of storing the values performed in this way are respectively provided to the opening control circuit 10b and the closing control circuit 10c. Is provided. The individual difference adjustment may be performed manually using a predetermined inspection device.
[0028]
By the way, even if the individual difference adjustment is performed as described above, the adjustment is performed under the above-described reference voltage. For this reason, at the beginning of battery replacement, the voltage of the power supply 8 is considerably larger than the reference voltage, and the voltage decreases as the image is taken and gradually approaches the reference voltage. . In the present embodiment, such voltage fluctuation is dealt with as follows.
[0029]
In this embodiment, the activation time t1 is set to two energization periods for convenience of explanation. The time t4 is one cycle. In other words, in the state of FIG. 2, it is energized continuously for two cycles under the reference voltage. Therefore, in this embodiment, the voltage comparison circuit 9 is provided between the power supply 8 and the motor control circuit 10, and the comparison information between the voltage of the power supply 8 and the reference voltage is always the startup control circuit 10a, The opening control circuit 10b and the closing control circuit 10c are individually provided.
[0030]
Therefore, the activation control circuit 10a shortens the energization time for each cycle in the activation time t1, based on the voltage comparison information, for example, so that the activation time becomes t5 so that the activation time t1 is not shortened. Yes. Therefore, the activation control circuit 10a is provided with such an automatic adjustment function. On the other hand, the opening control circuit 10b and the closing control circuit 10c are also provided with such an automatic adjustment function, and based on the adjustment value for each product by the individual difference adjustment performed as described above, the power supply 8 The larger the voltage is than the reference voltage, the shorter the energization time per cycle can be controlled.
[0031]
In the above-described embodiment, the end time of the activation time t1, the start time of the exposure control circuit 12 at the start of the exposure time, and the measurement start time of the time that is the evaluation criterion of the rise time are all photo. Although it is set as the output time point of the first light-shielding signal of the reflector 4, the present invention does not need to set these three time points as simultaneous points. In the above embodiment, the closing operation time (falling time) can be adjusted for individual differences, or can respond to fluctuations in the power supply voltage. It does not necessarily require that way and to Turkey. Further, in the above embodiment, the shutter blades 2 and 3 have been described as starting the closing operation after the opening 1a is fully opened, but the closing operation is started when the opening 1a is opened halfway. You can do that.
[0032]
【The invention's effect】
As described above, according to the present invention, since the stator coil is periodically energized at least during the opening operation of the shutter blade, the energization time as a whole can be shortened and the camera can be used. Since the power supply voltage fluctuations in the power supply can be adjusted automatically and separately at the start and after, it is possible to properly maintain the predetermined startability without using the constant voltage circuit. Exposure control can be performed. Moreover, it has a feature that individual difference adjustment at the time of production can be performed electrically.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of an embodiment.
FIG. 2 is a timing chart for explaining the operation of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shutter base plate 1a Opening part 1b, 2a, 3a Long hole 1c Window part 1d, 1e Shaft 1f, 1g Stopper 2, 3 Shutter blade 2b, 3b Detected part 2c, 3c Tip part 4 Photo reflector 4a Light emission part 4b Light reception part 5 Rotor 6 Shutter base plate 5a Drive pin 6 Coil 7 Magnetic member 8 Power supply 9 Voltage comparison circuit 10 Motor control circuit 10a Start control circuit 10b Open control circuit 10c Close control circuit 11 Motor drive circuit 12 Exposure control circuit 13 Detection circuit 14 Photometry circuit

Claims (3)

A plurality of first shutter blades and second shutter blades, each of which is provided with a portion to be detected, that open and close the exposure opening by rotating the first shutter blade and the second shutter blade about different axes. A plurality of shutter blades, detection means for detecting a plurality of operating positions by detecting the detected portion during at least opening operation of the plurality of shutter blades, and predetermined directions in different directions depending on the energization direction of the stator coil a motor for have a permanent magnet rotor which rotates by an angle ranging perform opening and closing the plurality of shutter blades, the plurality of the coil opening of the shutter blade from the start operation until at least close operation start Motor driving circuit for periodically supplying current to the coil, and per cycle supplied to the coil by the motor driving circuit A motor control circuit and a control circuit to open and start control circuit, wherein the energization time plurality of shutter blades are controlled separately by the time until a predetermined time and subsequent closing operation start before reaching the pinhole from the power supply It comprise a voltage comparator circuit for comparing the voltage with the design reference voltage applied to the motor drive circuit, wherein the detecting means is in the middle of the opening operation of the front Symbol plurality of shutter blades, initially the first The detected portion of the shutter blade is detected and a first position detection signal is output, and then the detected portion of the second shutter blade is detected and a second position detection signal is output, and the motor control circuit , the energization time per said one period, for the first position and the detection signal of the second position from the detection means, the predetermined time after the plurality of shutter blades by the opening control circuit Open to allow adjust the time of operation, the relative signal from the voltage comparator circuit, the activation control circuit and open all the time by the control circuit to start operation and close operation start opening of the plurality of shutter blades A camera shutter characterized by being adjustable.   2. The camera shutter according to claim 1, wherein the predetermined time is a time until the detection unit detects the first position. The motor control circuit includes a closing control circuit that periodically supplies current to the coil from the motor driving circuit even when the plurality of shutter blades are closed. at least the plurality of Oite in the middle of the closing operation of the shutter blade, and outputs a first detection signal of the third position by detecting the detected portion of the second shutter blade, the first shutter thereafter A detection signal of the fourth position is output by detecting the detected part of the blade, and the energization time per cycle in that case is the same as the case after the predetermined time in the opening operation of the plurality of shutter blades. The third position and fourth position detection signals from the detection means and the signal from the voltage comparison circuit can be adjusted, and the energization time after the adjustment is opened after the predetermined time. Camera shutter according to claim 1 or 2, characterized in that as always longer than the energization time during operation.

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